CA2097886A1 - Pressurized internal circulating fluidized-bed boiler - Google Patents
Pressurized internal circulating fluidized-bed boilerInfo
- Publication number
- CA2097886A1 CA2097886A1 CA002097886A CA2097886A CA2097886A1 CA 2097886 A1 CA2097886 A1 CA 2097886A1 CA 002097886 A CA002097886 A CA 002097886A CA 2097886 A CA2097886 A CA 2097886A CA 2097886 A1 CA2097886 A1 CA 2097886A1
- Authority
- CA
- Canada
- Prior art keywords
- air
- bed
- thermal energy
- energy recovery
- chamber
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F22—STEAM GENERATION
- F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
- F22B31/00—Modifications of boiler construction, or of tube systems, dependent on installation of combustion apparatus; Arrangements of dispositions of combustion apparatus
- F22B31/0007—Modifications of boiler construction, or of tube systems, dependent on installation of combustion apparatus; Arrangements of dispositions of combustion apparatus with combustion in a fluidized bed
- F22B31/0084—Modifications of boiler construction, or of tube systems, dependent on installation of combustion apparatus; Arrangements of dispositions of combustion apparatus with combustion in a fluidized bed with recirculation of separated solids or with cooling of the bed particles outside the combustion bed
- F22B31/0092—Modifications of boiler construction, or of tube systems, dependent on installation of combustion apparatus; Arrangements of dispositions of combustion apparatus with combustion in a fluidized bed with recirculation of separated solids or with cooling of the bed particles outside the combustion bed with a fluidized heat exchange bed and a fluidized combustion bed separated by a partition, the bed particles circulating around or through that partition
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN A CARRIER GAS OR AIR
- F23C10/00—Fluidised bed combustion apparatus
- F23C10/02—Fluidised bed combustion apparatus with means specially adapted for achieving or promoting a circulating movement of particles within the bed or for a recirculation of particles entrained from the bed
- F23C10/04—Fluidised bed combustion apparatus with means specially adapted for achieving or promoting a circulating movement of particles within the bed or for a recirculation of particles entrained from the bed the particles being circulated to a section, e.g. a heat-exchange section or a return duct, at least partially shielded from the combustion zone, before being reintroduced into the combustion zone
- F23C10/06—Fluidised bed combustion apparatus with means specially adapted for achieving or promoting a circulating movement of particles within the bed or for a recirculation of particles entrained from the bed the particles being circulated to a section, e.g. a heat-exchange section or a return duct, at least partially shielded from the combustion zone, before being reintroduced into the combustion zone the circulating movement being promoted by inducing differing degrees of fluidisation in different parts of the bed
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN A CARRIER GAS OR AIR
- F23C10/00—Fluidised bed combustion apparatus
- F23C10/02—Fluidised bed combustion apparatus with means specially adapted for achieving or promoting a circulating movement of particles within the bed or for a recirculation of particles entrained from the bed
- F23C10/12—Fluidised bed combustion apparatus with means specially adapted for achieving or promoting a circulating movement of particles within the bed or for a recirculation of particles entrained from the bed the particles being circulated exclusively within the combustion zone
- F23C10/14—Fluidised bed combustion apparatus with means specially adapted for achieving or promoting a circulating movement of particles within the bed or for a recirculation of particles entrained from the bed the particles being circulated exclusively within the combustion zone the circulating movement being promoted by inducing differing degrees of fluidisation in different parts of the bed
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN A CARRIER GAS OR AIR
- F23C10/00—Fluidised bed combustion apparatus
- F23C10/16—Fluidised bed combustion apparatus specially adapted for operation at superatmospheric pressures, e.g. by the arrangement of the combustion chamber and its auxiliary systems inside a pressure vessel
Abstract
ABSTRACT OF THE DISCLOSURE
A pressurized internal circulating fluidized-bed boiler is incorporated in a combined-cycle electric generating system in which a fuel such as coal, petro coke or the like is combusted in a pressurized fluidized bed and an exhaust gas produced by the combusted fuel is introduced into a gas turbine. The pressurized internal circulating fluidized-bed boiler includes a pressure vessel, a combustor disposed in the pressure vessel and a primary fluidized bed incinerating chamber provided with an air diffusion device. A thermal energy recovery chamber is partitioned from the primary fluidized bed incinerating chamber by an inclined partition wall. A fluidizing medium flows into and out of the primary incinerating chamber and the thermal energy recovery chamber.
A pressurized internal circulating fluidized-bed boiler is incorporated in a combined-cycle electric generating system in which a fuel such as coal, petro coke or the like is combusted in a pressurized fluidized bed and an exhaust gas produced by the combusted fuel is introduced into a gas turbine. The pressurized internal circulating fluidized-bed boiler includes a pressure vessel, a combustor disposed in the pressure vessel and a primary fluidized bed incinerating chamber provided with an air diffusion device. A thermal energy recovery chamber is partitioned from the primary fluidized bed incinerating chamber by an inclined partition wall. A fluidizing medium flows into and out of the primary incinerating chamber and the thermal energy recovery chamber.
Description
209738~
PRESSURIZED INTERNAL CIRCULATING FLUIDIZED-BED BOILER
BACKGROVND OF THE INVENTION
5 Field of the Invention:
The present invention relates to a pressurized internal circulating fluidized-bed boiler, and more particularly to a pressurized lnternal circulating fluidiæed-bed boiler for use in a pressurlzed fluidized-bed c~m~lned-10 cycle electric generating system in whlch a fuel such as coal,petro coke, or the like is combusted in a pressurized fluidized bed and an exhaust gas produced by the combusted fuel is introduced into a ~as turblne.
Description of the Prior Ar~-Efor~ to reduce the emlsslon of carbon dio~ide from various sources are lmportant ~n vlew of environmental damages that are being caused by air pollution which appears to be more and more serious on the earth. Tt is con~ectured that coal wlll have to be relied upon as a ma~or energy resourca because 20 greater dependency on nuclPar and oil energies is not favorable at present. To ~uppress carbon dioxide emission and provide a substitute for oil and nuclear power, there has been a demand for a hlghly efflcient, compact electric ~enerating system which ls capable of utillzing coal combustlon to generate a 25 clean ener~y~
To meet such a demand, atmospheric fluidized-bed boilers (AFBC) capable of burning coals of different ~lnds for electric ~eneration have been developed because a stable enersy supply cannot be achieved b~ pulverized coal ~ollers which pose r~, 20~7~6 a limitation on available coal types.
However, the atmo~pherlc ~luldlzed-bed bollers (AFBC) fall to perform the functlons that have bee~ expected. In addition, since only steam turbines can be combined with the 5 atmospheric 1uldized-bed boil~ers, there arc certain llmitations on attempts to increase the efficiency and energy output o~ the atmospherlc flui~1ized-bed boilers. These disadvantages of the atmospheric fluidized-bed boilers have directed research and development trend~ toward pressurized 10 1uidized-bed boilers (PFBC) that make lt possible to construct combined-cycle electrlc generating systems with ~as turbines.
One combined-cycle electric generating system which incorporate~ a conventional pressurized fluidized-bed ~oiler will be descrlbed below with reference to FIG. 15 of the 15 accompanying drawings.
A~ shown in FI5. 15, a pressure vessel 30 houses therein a combustor 31 which i5 supplled at its bottom with air under pressure from a compr~ssor 32. The pressure vessel 30 also aacommodate~ a bed ~aterial storage container 33 which 20 communicate~ with the combustor 31 to allow a fluidizing medium to move between the combustor 31 and the bed material storage container 33. The combustor 31 has a heat transfer tube 34 disposed therein which is connected to a steam turbine 35.
A dust collector 36 is posltioned ad~acent and 25 connected to an upper portion of the combustor 31. Dust particles contained in an exhau~t gas discharged from the combustor 31 are removed by the dust collector 36. Thereaft2r, the exhaust ga~ 1~ supplied to a ga~ turbine 37.
2097~8~
Operatlon of the pre~surized fluidized-bed electric generating system shown in FIG. 15 i3 as follows:
Coal i8 roughly crushed and supplied, together with a desul~urizer such as llmestone, to the combustor 31. In the 5 combustor 31, thsre i~ generated a fluidized bed, about four meters high, by air supplied under pressure from the compressor 32, the fluidized bed being composed of a fluidizing medium compriiing a mixture of a bed material, coal, a desulfuriz~r, ash, etc. The coal is mixed with air in the fluidized bed, and 10 combusted under pressure. Heat yenerated in the fluidized bed i8 recovered as steam by the heat transfer tube 34 in the fluidized bed. The steam is supplled rom the heat transfer tube 34 to the steam turblne 35, whlch is rotated to actuate an electric generator coupled thereto.
The exhaust gas produced by thei combustion of the coal in the combustor 31 is supplled to the dust collector 36, which removes duit particles from the e~haust ga3. The exhaust gas is then suppl~ed from the dust ~llector 36 to the gas turbine 37, which actuates the compres~or 32. Resldual energy 20 contained in the exhauQt gas actuates an electric generator coupled to the gas turbine 37.
The exhau~t gas discharged from the outlet of the gas turbine 37 i~ supplied to a denitrification unit 45 which reduces the NOx content and smoke dust in the exhaust gas. The 25 waste heat of the exhaust gas is then recovered by an economizer 38. Thereafter, the exhaust gas is discharged from a smok~ stack 39.
The E)ressurized ~luidlzed-beid electric generating ,r~
PRESSURIZED INTERNAL CIRCULATING FLUIDIZED-BED BOILER
BACKGROVND OF THE INVENTION
5 Field of the Invention:
The present invention relates to a pressurized internal circulating fluidized-bed boiler, and more particularly to a pressurized lnternal circulating fluidiæed-bed boiler for use in a pressurlzed fluidized-bed c~m~lned-10 cycle electric generating system in whlch a fuel such as coal,petro coke, or the like is combusted in a pressurized fluidized bed and an exhaust gas produced by the combusted fuel is introduced into a ~as turblne.
Description of the Prior Ar~-Efor~ to reduce the emlsslon of carbon dio~ide from various sources are lmportant ~n vlew of environmental damages that are being caused by air pollution which appears to be more and more serious on the earth. Tt is con~ectured that coal wlll have to be relied upon as a ma~or energy resourca because 20 greater dependency on nuclPar and oil energies is not favorable at present. To ~uppress carbon dioxide emission and provide a substitute for oil and nuclear power, there has been a demand for a hlghly efflcient, compact electric ~enerating system which ls capable of utillzing coal combustlon to generate a 25 clean ener~y~
To meet such a demand, atmospheric fluidized-bed boilers (AFBC) capable of burning coals of different ~lnds for electric ~eneration have been developed because a stable enersy supply cannot be achieved b~ pulverized coal ~ollers which pose r~, 20~7~6 a limitation on available coal types.
However, the atmo~pherlc ~luldlzed-bed bollers (AFBC) fall to perform the functlons that have bee~ expected. In addition, since only steam turbines can be combined with the 5 atmospheric 1uldized-bed boil~ers, there arc certain llmitations on attempts to increase the efficiency and energy output o~ the atmospherlc flui~1ized-bed boilers. These disadvantages of the atmospheric fluidized-bed boilers have directed research and development trend~ toward pressurized 10 1uidized-bed boilers (PFBC) that make lt possible to construct combined-cycle electrlc generating systems with ~as turbines.
One combined-cycle electric generating system which incorporate~ a conventional pressurized fluidized-bed ~oiler will be descrlbed below with reference to FIG. 15 of the 15 accompanying drawings.
A~ shown in FI5. 15, a pressure vessel 30 houses therein a combustor 31 which i5 supplled at its bottom with air under pressure from a compr~ssor 32. The pressure vessel 30 also aacommodate~ a bed ~aterial storage container 33 which 20 communicate~ with the combustor 31 to allow a fluidizing medium to move between the combustor 31 and the bed material storage container 33. The combustor 31 has a heat transfer tube 34 disposed therein which is connected to a steam turbine 35.
A dust collector 36 is posltioned ad~acent and 25 connected to an upper portion of the combustor 31. Dust particles contained in an exhau~t gas discharged from the combustor 31 are removed by the dust collector 36. Thereaft2r, the exhaust ga~ 1~ supplied to a ga~ turbine 37.
2097~8~
Operatlon of the pre~surized fluidized-bed electric generating system shown in FIG. 15 i3 as follows:
Coal i8 roughly crushed and supplied, together with a desul~urizer such as llmestone, to the combustor 31. In the 5 combustor 31, thsre i~ generated a fluidized bed, about four meters high, by air supplied under pressure from the compressor 32, the fluidized bed being composed of a fluidizing medium compriiing a mixture of a bed material, coal, a desulfuriz~r, ash, etc. The coal is mixed with air in the fluidized bed, and 10 combusted under pressure. Heat yenerated in the fluidized bed i8 recovered as steam by the heat transfer tube 34 in the fluidized bed. The steam is supplled rom the heat transfer tube 34 to the steam turblne 35, whlch is rotated to actuate an electric generator coupled thereto.
The exhaust gas produced by thei combustion of the coal in the combustor 31 is supplled to the dust collector 36, which removes duit particles from the e~haust ga3. The exhaust gas is then suppl~ed from the dust ~llector 36 to the gas turbine 37, which actuates the compres~or 32. Resldual energy 20 contained in the exhauQt gas actuates an electric generator coupled to the gas turbine 37.
The exhau~t gas discharged from the outlet of the gas turbine 37 i~ supplied to a denitrification unit 45 which reduces the NOx content and smoke dust in the exhaust gas. The 25 waste heat of the exhaust gas is then recovered by an economizer 38. Thereafter, the exhaust gas is discharged from a smok~ stack 39.
The E)ressurized ~luidlzed-beid electric generating ,r~
2~97~
system shown ln FIG. 15 i8 controlled to meet a load lmposed thereon by varying the helght of the fluldlzed bed ln the combustor 31. More ~peclfically, the fluidizing medium i8 , drawn from the cQmbustor 31 into the bed material storage 5 container 33 to expose heat transfer surfaces of the heat transfer tube 34, thereby controlling the heat generation to meet the load. When the heat transfer surfaces of the heat transfer tube 34 are ~xposed, the heat tran~fer coefficient - thereof is lowered, and hence the amount of heat recovered i~
10 lowered. Since the exhaust gas emitted from the fluidized bed is cooled by the exposed heat transfer ~urfaces, the temperature of the exhaust gas supplied to the ga~ turbine 37 is lowered, thus reducing the output energy of the gas turbine 37. However, the above control proces~ i~ dlsadvantageous in 15 t~at the bed matsrial storage container 33 1~ nece.qsary to with~raw and return the high-temperature flu~dizing medium from and into the combustor 31, it ls not easy to withdraw and return the fluldizing medium at high temperature and pressure, and agglomeration tends to occur when the 1uidi~ing medium 20 partlcles of high heat density are taken in~o and out of the bed material storage container 33.
Furthermore, ~ince the pres~urized flu~dized-bed boilar is under pressure, the heat transfer tube 34 in a splash zone of the fluldized bed is more sub~ect to ~ear than that in 25 thP atmospheric fluldized~bed boilers. Anot~r problem ls that an large amount of carbon monoxide is produced because the exhaust ~as emitted from the fluidized bed ~s cooled by the heat transfer tube 34 and the e~haust gas remains in the r~, 20~7~8~
fluidized bed for a short period of time a8 the helght of the fluidlzed bed 18 reduced.
As described above, l:Lmestone i8 mixed with the fluldizing medium for desulfurization ln the conventional 5 pressurized fluidized-bed electric generating ~ystem shown in FIG. 15. However, the lime~tone wears rapidly, and is scattered as ash from the dust collector 36 wlthout sufficiently contributing to the desulfurizlng action. The conventional pressurized fluidlzed-bed electric generating lO system fails to achieve a high de~ulfurizatlon rate that are required by thermal power plants. If the de~ulfurization rate is increased, then the conventional pressurized fluldized bed electric generating system produces a vast amount o~ scattered ash.
SUMMARY OF THE INV~NTION
It ls therefore an ob~ect of the present invention to provide a pressurized internal circulat~ng fluidized-bed boller ~or a combined-cycle electric generating syste~ 9 which can be controlled to meet a load without varying the height of a 20 fluidized bed, minimizes the ~eneratton of agglomeration and carbon monoxide, and can increase a limestone utilization ratio and a desulfurization rate.
According to the present ~nvention, there is provided 25 a pressurized internal clrculat~ng fluidized-bed boiler for use in a combined-cycle electric generating system, comprising: a pressure vessel: a aombustor disposed ln sa~d pressure vessel;
a primary fluidized bed incinerating chamber having an air ~ 20~7~
diffusion device provided at the bottom of ~aid combustor and adapted to inJect fluidizl~ air upwardly under a mas~ flow that is at least greater at one side than that at another side;
an inclined partition wall provided above a portion of said air 5 diffusion device where the mas~ flow is greater so as to interfere with the upward flow of the flu~dizing air and thereby to deflect the air towards a portion above sald another side of ~aid air diffusion devic:e where the mass flow is imaller; a thermal energy recovery chamber partitioned from 10 said lncinerating chamber by sald incllned partition wall; a heat transfer surace means provided in said thermal energy recovery chamber for a passage of a heat receiving fluid therethrough, and an air diffuser provided at a lower portion of said thermal energy rPcovery chamber; wherein said 15 thermal energy recovery chamber 1s communicated at upper and lower portions thereof with said pri~ary fluidized bed incinerating chamber, a moving bed i8 for~ed above the portlon of said air diffusion device where the in~ected mass flow l~i smaller so that a fluidizing medium descends and diffuses 20 within the moving bed, and a circulating fluidlzed bed is formed abovP the portion of said alr diffusion devlce where the mass flow of the fluidizing alr i8 greater ~o that sai~
~luidlzing med~um is actively fluidized and whirled towardi a position above said moving bed and a part of siaid fluldiz~ng 25 medium is introduced lnto said thermal energy recovery chamber beyond an upper portion of said lnclined partitlon wall, the format~on of said moving bed and said circulating fluld~zed bed is effected by reyulation of the amo~nt of air in~ected 20~ l8~i .
upwardly from said air diffusion devlce and regulation of the fluidlzing air lnJected from said air diffuser in said thermal energy recovery chamber causes the fluidizing medlum wlthin said recovery chamb~r to descend in a state of a moving bed for 5 clrculation.
With the above arrangement of the present inventlon, since the incinerating chamber and the thermal energy recovery chamber are functionally ~eparated from each other within the combustor, the boiler ¢an be controlled to ~eet a load simply 10 by varying the overall heat transfer coefficlent of the heat transfer tubes through ad~ustment of the amount of alr ~ntroduced into the thermal energy recovery chamber, rather than by varying the height of the fluidized bed in the lncinerating chamber. Therefore, no complex process and 15 equipment is necessary to take the fluidizing medium into and out of the incinerating chamber and the ther~al energy recovery chamber, and no agglomeration is generated ~8 the fluidiz~ng medium flows into and out of the incinerating chamber and the thermal energy recovery chamber. Since the temperature of the 20 fluidized bed i8 kept at a constant level even when the load on ~he boiler varies, the boiler can be operated under a temperature condition opt~mum for the suppression of NOx, SOx, and other undesirable emission~. Inasmuch as the heat transfer tubes are positioned only in the thermal energy recovery 25 chamber whioh is exposed to a gradual flow of the fluid~zing medium, tha heat transfer tu~es are less sub~ect to wear than would be if they were placed in the fluidized bed which is in a v~olent flow conditlon.
l rl 8 ~ ~
As swlrllng flows are developed ln the fluidized bed, the fluldizing medlum does not stay stagnant in the fluidlzed bed, and the fuel such as coal or petro coke i5 uniformly dispersed and combusted, with no agglomeration produced. The 5 amount of carbon monoxidei produced is kept low becauie the exhau~t gas emitted from the fluldized bed i8 not cooled by the heat transfer tubeqi in the fluldlzed bed.
The above and other ob~ert3, features, and advantages of the present invention will become apparent from the 10 following description when taken ~n con~unction with the accompanying drawings which illustrate preferred embodiments of the present invention by way of example3.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. l 1i5 a schematic view of a comblned-cycle 15 electrlc generatlng system which lncorporates a pressurized internal circulating fluidized-bed boiler according to an embodiment of the present invention;
FIG. 2 ls a cross-~ectional view o the pressurlzed internal circulatlng fluldlzed-beid boiler;.
FIG. 3 is a cross-sec~ional view showing the detailed structure of the pressurized internal circulating fluid~zed-bed boiler FIG. 4 isi a graph show~ng the relationship between the amount of alr for fluidization (Gmf3 at the portion below 25 the incllned partition wall in the primary fluidized bed lncinerating chamber and the amount o the fluidiziny medium circulated;
FIG. 5 is a graph showing the relationshlp between : ~0~788~
. ~.`
ths amount of diffusing air (Gmf) in the thermal energy recovery chambar and the de~cending rate of the downward movlng bed in the thermal energy recovery chamber;
FIG. 6 is a graph ~howing the relationship between 5 the mass ~low for fluidization (Gmf) and the overall heat transfer coefficient in the conventlonal bubbling type boiler;
FIG. 7 is a graph showing the relatlon~hip between the dlffusio~ mas~ flow (Gmf~ in the thermal energy recovery chamber and the overall heat transfer coefficlent ln the 10 pressurized internal circulating fluidized-bed boller according to the present invention;
FIG. 8 is a graph showlng the relationshlp between the mass flow for fluidization and the abrasion rate of the heat transf~r tube;
FIG. 9 i~ a graph showing varlations relative to the lapse of time in the steam amount and stea~ pressure in respons~ to stepwise ahange of the steam flow rate;
FIG. 10 1~ a graph showing variation~ relative to the lapse of time in temperature o~ th~ fluidized bed;
FIG~ 11 shows simllar varlation~ relative to the lapse of time in response to continuously stepwise change of the steam flow rats;
FIG. 12 show~ a fl~idizing pattern in the primary fluidized bed incineratin~ chamber with the relationship 25 between the horizontal length L of the incinerator bottom and the proJectlon length of the inclined partltion wall in the horizontal direction;
FIG. 13 shows a fluidizing pattern in the primary 9 ~.
209'^~88~
fluidized bed incineratlng chamber with the relatlonshlp between the horizontal length L of the lncinerator bottom and the pro~ection length of the incllned partition wall ln the horizontal directlon;
FIG. 14 show~ a fluidlzing pattern in the primary fluidized bed incinerating chamber with the relationship between the horizontal length L of the incinerator bottom and the proJection length of the incltned partition wall in the horizontal d~rectlon; and FIG. 15 ls a schematic view of a conventional combined-cycle electrlc generating system which incorporateis a pressurized ~iluidized-bed bo~ler.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
FIG. 1 ~chematically showY a combined-cycle electric 15 generatln0 syste~ which incorporates a pressurized lnternal circul~ting fluidized-beid boller according to the presen~
lnvention. As shown in FIG. 1, the combined-cycle electric generating ~yste~ include~ a pressure ve~el 1 houcing a combustor 2 therein. The preis3ure vessel `l communtcates with 20 a compressor 3 which keeps a predetermined prsssure in the pressure ves~el 1. The combustor 2 accom~odates heat transer tubes 4 connected to an inlet of a steam turbine 5 whose outlet is coupled to the hcat transfer tubes 4 through a oondenser 6 and an economizer 7. The heat transfer tubes 4, the steam 25 turbine 5, the conden~er 6, and the economizer 7 Jointly constitute a steiam cycle system.
An ~xhaust gas i~ di~charged from an upper end of the combustor 2 and lntroduced into a gas turbine 9 through a 788~j multistage dust collector 8. The exhaust gas discharged from the gas turblne 9 ls ~upplied to an economizer 7 for heat recovery, and then discharged from a smoke stack 10. Ash, char, fine lime particle~ or the like collected by the first 5 stage of the dust collector 8 are returned to a free board sectlon of the combustor 2.
The pressurized lnternal circulating fluidized-bed boiler wlll be describ~d in detail below with reference to FIGS. 2 and 3.
As shown i~ FIG. 3, the combustor 2 houses a fluidizing air diffuslon device 12 composed of a horizontal array of fluidizing air nozzles 12n on the bottom of the combustor 2. The fluidi~ing air diffusion device 12 has oppo~ite slde portions A, C lower than a csntral portion B
15 thereof. These slde and central portio~ A, B, C are ~ointly of a roof shape which ls s~mmetrical with respect to a vertical central axis of the combustor 2. Fluidizing air is supplied from the compressor 3 through a fluidizing alr conduit 21 to the fluidizing alr nozzle3 12n, from which the fluidizing air 20 is e~ected upwardly lnto the combustor 2. The ma s flow of the fluidiziny air e~ected from the air nozzles 12n of the side portions A, C of the fluidizing air diffusion device 12 is a speed high enou~h to for~ a fluidized bPd of a fluidizing medium in the combustor 2. The mass flow of the fluldizing air-~5 ejected from the air nozzles 12n of the central portion B ofthe fluidizing air diffuslon device 12 i8 smaller than the mass flow of the fluidizlng alr e~ected from the air nozzles 12n of ~h~ side portions A, C of the fluldizlny air diffuslon device ,; , . . . .
~ 2~7:~8~
12.
A partltlon wall 18 i9 dispo~ecl slightly above the respec~lve oppo~ite end~ of the fluldiz$~g air diffu~ion device 12. The partitlon wall 18 define a primary incineratlng 5 chamber in the combustor 2. The partition wall 18 comprlses a vertical partition wall 18a and an inclined partition wall 18b.
The inclined partition wall 18b se:~es as a reflective wall for r~flectlng the flu~z~ng air eJec:ted from the air nozzles 12n of the side portions A, C toward the center of the combustor 2.
10 Because of the lnclined partition wall 18b and the difference between the mass flows of the e~ected fluldizing air, swirling flows of the fluidizing medium aIe developed in the combustor 2 as indlcated ~y the arrows in FIG. 3. A thermal energy .recovery chamber 19 15 defined bet~een the back of the 15 partition wall 18 and the wall of the combu~tor 2. Whlle the combu3tor 2 18 in operation, a part of the fluidizing medlum flow over the upper ed~e of the inclined partition wall 18b into the thermal ener~y recovery chiamber 19. ~he heat transfer tubes 4 are disposed ln the thermal energy recovery chamber 1 20 for recovering thermal energy from the fluidizing medlum flowing downwardly ln the thermal energy recovery chamber 19 through a heat exchange wlth the fluidizlng m~dium.
The lnclined partition wall 18b ~s inclined to the horizontal planie by an angle in the range of from 10~ to 60, ~5 preferably 25 to 45~ The horizontal len~th 1 of the ~nclined partition wall 18b as ~t i pro~ected onto the bottom of the lncinerator i~iln the range of from 1/6 to 1/2, preferably from 1/4 to 1/2, of the horizontal length L of the bottom of the :
~ 2~78~
incinerator.
The angle of inclination of the inclined partition wall 18b to the horlzontal plane and the horizontal length l of the inclined partition wall 18b a~ lt is projected onto the 5 bottom of the incinerator affect the fluidized state of the fluidizing medium in the primary lncinerating chamber in the incinerator and the amount of particles that enter the thermal energy recovery chamber 19. The ]Length~ ~, 1 and the flow of the fluidizing medium are shown in FIG. 120 If the angle of inclinat:Lon of the inclined partition wall 18b to the horizontal plane were smaller than 10 or larger than 60, then no good swirlin~ flows would be created, and the fuel such as coal would not be combusted well. The angle of inclination o~ the lnclined partition wall 18b to the 15 horlzontal plane should preferably be in the range of from 25 to 45, and more preferably be about 35.
If the horlzontal length l of the inclined partition wall 18b as it ls pro~cted onto the bottom of the ~ncinerator were yreater than 1/2 of the horizontal length L of the bottom ~0 of the lncinerator, then the fluidizing medium reflected back by the inclined partition wall 18b would be blown up as shown in FIG. 13. Since the fuel would also be blown up, the fuel charged in the prlmary i~clnerating chamber would not be burned effectively.
If the horlzontal length l of the inclined partitlon wall 18b as lt 18 projected onto the bottom of the lnoinerator were smaller than 1/6 of the horizontal length L of the bottom of the incinerator, then the ~wirling 10ws of the fluid~zing 20978~fi medium in the primary incineratlng chamber would be deteriorated, and the moving bed ln the central region of the inainerator would not be formed suffiGiently. The uel entraining and diffusing effect would be iDpalred, and the 5 fluidizing medium would not sufficiently b~ deflected into the thermal energy recovery chamber 19.
An air diffuser 22 ls disposed ln a lower portion of ~he thermal energy recovery chamber 19 for introducing a gas or air from the compressor 3 through a condu$t 21 into the thermal 10 energy recovery chamber 19. As shown ln FIG. 3, the air diffuser 22 comprises an inclined plate 23 havlng an array of nozzles 23n, the inclined plate 23 being progressively inclined outwardly toward the wall of the combustor 2. An opening 24 is defined near the air diffuser 22 vertically between the lower 15 end of the partltion wall 18 and the inner end of the alr di~fuser ~2. The fluidizing medlum tha* ha~ entered the thermal energy recovery chamber 19 descends therein while forming a moviny bed continuously or inter~ittently depending on the operat~ng condition of the boiler, and is circulated 20 through the opening 24 lnto the primary incinerating chamber.
Another alr diffu er 29 ls mounted on the bac~ of the inclined partition wall 18b ln an upper portion of the thermal energy recovery chamber 19. ~he air difuser 2~ e~ects air to blow, combust, agltate, and diffuse the coal that has entered 25 the thermal energy recovery chamber 19. No heat tr nsfer tubes are located ln the vicinity of the air diffuser 29, l.e., the air diffuser 29 i positioned remotely fro~ the heat transfer tubes 4.
2 ~ 9 7 ~
The descending amount of the fluidizing medlum in the thermal energy recovery chamber 19 for clrculatlng i~ regulated by the amount of diffuslng air for the then~al energy recovery chamber and the amount o fluidizing air for the incinerating 5 portion. That ~, the amount of fluidizing mediu~ (G1) introduced into the terminal en~rgy recovery chamber 19 is increased 2~ shown in FIG. 4 when the ~mount oP fluidizing air in~ected from the air diffu~lon device 12, particularly the amount of fluidizing a~r ln~ected :Erom the nozzles 12n disposed 10 on both s~de portion~ A, C i~ increased. Further, as shown in FIG. 5, the amount of fluidlzing medlum descendlng in the thermal energy recovery chamber 19 is approximately proportionally changed with respect to the change ln the amount of dlffuslng air blown into the thermal energy recovery chamber 15 19 when the amount of diffu~ing alr for the thermal energy recovery chamber is in the range of 0-1 Gmf. The amount of fluldizing medium descendi~g in the th~rmal energy recovery chamber 19 becomes approximately constant when the amount of diffusing air for the thermal energy recovery chamber is beyond 20 1 Gmf. This constant amount of fluldizlng medium is almost equivalent to the amount of fluidizing medium (Gl) introduced into the thermal energy recovery chamber and thu~ the amount of fluidizing medium descendlng in the thsrmal energy recov~ry chamber becomes equivalent to a value corresponding to G~. By 25 controlling the air amount both for the incinerating portion and the recovery chamber, the descending amount of fluidizing medium ln the thermal energy recovery chamber 19 may be regulated.
2~8~
The descent of the fluidizing medium in the static bed in the range of 0-1 Gmf depend~ on the weight d~fference (the difference in hslght of the fluidized beds) between the fluidizing medium in th~ thermal enS2r9y recovery chamber and 5 the fluidizing medium in the prlmary fluidizesd bed incineratlng chamber. In the case where the mas~ flow ls over 1 Gmf, the height of the moving bed portion becomes slightly h~gher or appro~imately equal to the other.
The clrculating of the fluidiztng medium i~ asslsted 10 by a deflecting flow with a sufficls~nt amount of fluidizing medium caused by the inclined part1tion wall.
Now, the relationship between ths~ height of the fluid~zed bed and the circulating amount of the fluidizlng mediums (the deflecting ~low) wlll S~e explained in detail.
In the case where the surace of the fluidized bed i~
lower than the upper end oP the inclined partition wall, the air flow movin~ upwardly along the inclined partition wall is given lts direction by the incllnad partition wall, flow~ along the inclined partition wall and i~ in~ected from the flu~dized 20 bsd, whereby the fluidizing medium is accompanied therewith.
The inJected alr flow is put in a ~tate different from that in the fluidized bed and freed from the fluidizing medium with which the fluidized bed 1~ filled. Thereafter the sectional area of the air flowin~ passage is ~uddenly Rnlarged, the 25 in~ected air flow is dlffused and reduce~ its ~peed to a few mJs to thus become a gentle flow, and is discharged upwardly~
Therefore, the fluldizing medium accompanied by the inJected alr flow lose~ its kinetic energy and falls downwardly due to 2 ~
gravity and the frictlon wlth the exhaust ga~ as the grain size of the fluldlzing medium i8 too large (approximately 1 mm) to be carried with the air flow.
In the case where the ~urPace of the fluidizing bed 5 i~ higher than the upper end of the inclln0d partition wall, a part of the fluldizing air gathered by the partition walls is in~ected along thei deflecti~g partltlon wall toward a certain direction in such a manner similar to that in the circulating fluidized bed inclnerator, whilteti the other part, due to a 10 sudden boiling phenomenon derived from the explosion of bubbles, i3 boiled upwardly like flre works ~uist abovt2 the upper end of the incllned partition wall and falls over all around the periphery. Accordingly, a part of the fluidizing medium is introduced ln a large amount lnto the bacl~ side of 15 ths partition wall, i.e. the thermal energy recovery chamber.
That i8, the ~ov~ng direction of the ln~ected fluidizlng ~nedium becomes closer to upright ais the surface of the fluldizlng bed becomes higher than the upper end of the inclined partitlon wall. Therefore, the amount of iEluidizing 20 medium introduced into the thermal energy recovery chamber becomes larger ln the case where the surface of the fluidizlng bed i~ slit3htly above the upper end of the inclined ~artition wall .
FIG. 4 shows the relationship between the amount of 25 fluidizing air in thP portion below the inclined partition wall in the primary fluidizing bed incinerating chamhter and the amount of fluidizing medium circulatt2d through the thermal energy retticov~ry chamher 209 ~88~
For example, durlng the operatlon und~r the ~tate Ll, lf the helght of the fluidlzed bed ls lowered due to the scattering of the abraded ~luidizing medium, the circulating amount of ~he fluidizing medlum i8 suddenly reduced to, for 5 example, helow 1/10 of that of the former and thermal energy recovery cannot be performed. Thus, what is important ls the amount of the fluidizing air and, ln the ca~e where it ls arranged to be more than 4 Gmf and preferably ~ore than 6 Gmf, the value of G1/Go is malntained over 1 and the required and 10 sufficient amount of the circulating fluidizing medium may be obtained even if the height of the fluidized bed is changed.
Further, by arranging the mass flow of the air in~ected Prom the air diffuser 22 in the bottom of the thermal energy recovery chamber to be 0-3 Gmf, or preferably 0~2 Gmf, 15 and the mas~ flow of the fluldizing air in~cted from the air diffusion device 12 dl~posed below the inçlin~d partition wall to be 4-20 Gmf or preferably 6-12 Gmf, that i~, by always keeplng the ma~s flow to be larger at the incin~ra~ing chamber side than at the thermal energy recovery chamber side, the 20 amount of fluidlzing medium fed back to the primary fluidized bed incinerating chamber from the thermal energy recovery chamber may ~e regulated.
As to the moving bed in the thermal energy recovery chamber, lt is referred to in the aeade~ic sense as a static 25 bed when the mass flow i~ 0-1 Gmf and a fluidized bed when the mass flow is ovar 1 Gmf, and it is co~monly known that a minimum mas~ flow of 2 Gmf i8 required to form a stable fluidtzed bed. On the other hand, in the case of the moving 209~86 bed accordlng to the present invention, whlch ls always d~scendin~ and movlng, the de~cending moving bed 18 satisfactorily formed untll the mass flow is increased up to the order of about 1.5-2 Gmf without causing the destruction of 5 the moving bed by the bubbling phenomen~n. Xt ls assumed that the grains of the fluidlz$ng medlum gradually de~cend and move under a vibratlng mode whereby the fluidi~ing air is converted into small alr bubbles uniformly flowing upward towards the upper portion of the moving bed.
The heat transfer coeff:Lcien~ in the thermal energy recovering portion i8 greatly varled as shown in FIG. 7 when the amount of the diffusing air ln the thermal energy recovery chamber is changed ln the rang2 of 0-2 Gmf.
Now the characterl~tics such as the load response 15 characteristlcs caused by the formation o~ the moving bed in the thermal energy recovery chamber will be explained.
The general relationship b~ween the overall heat transf~r coefflcient and the mas~ flow for fluldization is shown in FIG. 60 Between the values of the mass flow in the 20 range of 0-1 Gmf, the increase in the heat transfer coefficient is small. The heat transfer coefficient su~denly increases when the mass flow becomes over 1 Gmf. As a method for turning down the fluldized bed boiler utilizlng the above phenomeno~, the "Wing Panel Type" i~ disclosed in DOE Report, 6021 (2)~
25 655-663 (1~85) and the heat transfer coefflcient in response to the variation of the flu~dizing mass flow is descrlbed to be insensitive (s~atic bed) or too sensitive (fluidized bed).
Incldentally, upon revlewing certain fore~gn patent 2~7~
speclfications, several cases are found which seem to be slmilar to tha present technology in the point that the inclneratlng chamber and the thermal ~nergy recovery chamber are separated. However, all the partitions disclosed therein 5 are provided in a vertical direction, and the flu~dizing medium in the thermal energy recovery ch~ber is ln the mode for being changed to the static bed and to the fluidizing bed, it being the ~tatic bed when the thermal energy recovery ls small in amount and the fluidlzing bed in which the medium ls blown 10 upwardly from the lower portion when the thermal energy recovery is large ln amount. This is because lt is difficult to produce a deflected flow with a vertically oriented partition a~ compared to the case where the partition ls inclined. It 13 therefore inevitable in the vertically 15 oriented partit~n that the fluidizing medlum i~ arra~ged in both the i~cineratin~ chamb~r and the ther~al energy recovery chamber to be in a fluidized state (simll~r to water) 80 ~hat the fluidizing medium ls caused to flow between the two chamber~.
The relationsh~p between the overall heat transfer coefficient and the mass flow for fluidlzation is shown in FIG.
7. As shown in FIG. 7, the overall heat transfer coefficient changes almost linearly and, thu~, the amount of thermal energy recovered and the temperature of the pri~ary fluidlzed bed 25 lncinerating chamber may be controlled opt~onally. Further, such control may be easily efscted simply by regulating the amount of diffusing alr in the thermal energy recovery chamber.
Further, it ls sald that the abr~sion rate of the 20~7886 heat transfer tubes in the fluidized bed i8 ~roportlonal to the cube of the mas~ flow for fluldlzation and such relationship is Yhown in FIG. 8. Accordingly, the problem of abrasion regarding the heat transfer tube~ may be ~olved by arranging 5 the amount of dlffusing air blown into the moving bed in the thermal energy recovery chamber to 0-3 Gmf or preferably 0-2 Gmf.
In order to regulate the amount of thermal energy recovered, regulation of the amount of circulatlng fluidizing 10 medium i~ effected, as explained before, while e~fecting simultaneous regulation o the heat transfer co~fficient. That is, in the case where the amount of diffusing air in the thermal energy recoveir~ chamber is increased, the amount of circulating fluidizing medium i~ increased and the heat 15 transfer coefficlent 1~ ~imultaneously incr~ased to greatly increase the amount of thermal energy recovered by synergistic effect of the two ~actors~ From the viewpoint of the temperature of the fluidi~ng medium in the fluidized bed, the above corr~sponds to the effect of preventing the temperature 20 of the fluidizlng mediu~ from ~eing raised above the predetermined temperature.
As a means for introducing the dlffusing air into the thermal energy recovery chamber 19, several means may be considered, but it is generally di pos~d on thR bottom of the 25 thermal enerjgy recovery chamber 19 so as to effectively utillze the space in the thermal energy reco~ery chamber.
Further, ln the alr diffu~er 22, tha dlffusing air from the nozzles 23n ~ in~ected toward the incineratin~
~1 2 0 19 7 ~
chamber ~o that the fluldlzing medlum can be ea~lly lntroduced lnto the inclnerating chamber.
~ he respective sizes of the nozzles are preferably determined so that an approximately unifor~ dif~u~ing amount is 5 in~ected over the full length of the air diffuser 22 with the diffusing air amount being 2 Gmf. That i8, wh2n the above is satisfied, it is pos~ible to obtain the maximum amount of thermal energy recovered by all the heat tran~fer surfaces in the thermal energy recovery cham~er and the abra3ion rats of 10 the heat transfer surfaces may be kept small over all the sur:EaceQ .
In FIG. 3, a combustible charge inlet 26 is provided at the upper portion of the lncinerator. Combustibles such as coal or petro coke are ~upplied to the co~bu~tor 2 through the 15 combustible charge inlet 26 by a pneu~atic conveyor (not shown3.
Next, operatlon o~ the pressurized internal circulatlng fluidized-bed boller thus c~n~tructed will be described below.
The combustible~ F charged through th~ combustible charge inlet 26 are circulated and combusted in the $1uidizlng medium which i~ circulated under the influence of the circulatin~ flow caused by the fluidizing air. At this time, the fluid$zing medium at the central portion B above the air diffusisn device 25 12 ~s not accompanied by a violent up-and-down motion thereof and form~ a descending moving bed which is in a weak fluidizing state. The wldth o~ this movln~ bed i~ narrow at the upp~r portion thareof and the trailing ends thereof are extended in 2~78~
the opposite directlons to reach the portions above both slde portlon~ A, C of the air dlffusion devlce 12, thus the fluidizing medium is ~ubJected to the fluldlzlng air in~ected at a greater mas~ flow from ~oth side portion~ A, C and is 5 blown upwardly. Accordingly, a portinn of each trailing end is displaced and, thus, th~ bed ~u~t above the central portion B
descends under gravity. Abo~e thi~ bed, the fluidizing medium pile~ up by being supplemented f`rom the fluidizlng bed, as explained later, and the flu1dizing medium above the air 10 diffusion device 12 forms a gradually and cont~nuously descending moving bed with the repetition of the above modes.
The fluidizing medium moved above both side portions A, C is blown upwardly and deflected and whirled by the inclined partition walls 18b toward~ the center of the 15 incinerator and falls on the top of the central moving bed and i~ circulated again as explained b~fore. A part of the fluidizin~ medlum ls introduced into the thermal energy recovery chambers 19 beyond the upper portions of the inclined partltion wall3 18b. In the cas~ where the descending rate of 20 the fluidizin~ medium in the thermal energy recovery chamber 19 i8 slow, the angle of repose for the fluidizlng medium is formed at the upper portion of the ~hermal energy recovery chamber and the excess fluidizing medium falls from the upper portio~ o~ the inclined partition wall 18b to the primary 25 fluid~zed bed incinerating chamberO
The ~luidizing medium intrnduced into the thermal energy recovery chamb~r 19 forms a gradually descending moving b~d du~ to the ga~ in~ected from the air dluser 22 and it is r~
20~78~6 ., returned to the primary fluidized bed incin~,r~ting chamb~r from the opening portlon 24 after the heat transfer i~ effected with the heat transfer tubes.
The mass flow o~ the diffusing air introduced from 5 the air diffuser 22 ln the thermal energy recovery chamber 19 is selected from values in the range of 0-3 Gmf or preferably 0-2 Gmf.
The reason for the above i8 that, as shown in FIG. 7, the heat transfer coefficlent varies from the minimum to the 10 maximum below the value of 2 Gmf and the abraslon rate can be controlled, as shown in FIG. 8, within a small range.
Further, the thPrmal energy recovery chamber is located outside the ~trong corroslve zone of the primary *luidized bed lncinerating chamber under the reducing 15 atmospheres and, thus, the heat tran~fer tubes 4 are subJected to less corrosion as compared to the conventional one~ and the degree of abrasion of the heat transfer tubes 4 i8 made quite small because the fluidizing ra$e in thi~ section is, as explained beore, low. A~ to the speed of air flow ln the 20 fluidizing air with mass flow ranglng 0-2 ~f, it is 0-0.4m/sec (superficial velocity) at 800~ which i~ quite low while it practically depends on the $emperature and grain size of the fluidi~ng medium.
Regarding the heat transfer in the thermal energy 25 recovery chamber 19, in addition to the heat transfer that takes place dus to the direct contact between the fluidizing medium and ~he heat trans-Eer tube~ 4, there is another form of heat transfer that utilizes the ris~ng gas moving upwardly wlth 2 0 ~ '7 ~ ~ ~
irregular vibration as the fluldlzlng ~edium move~. In the latter case, there 18 substantlally no boundary layer between the solid articles checklng or preventing the heat tran~fer, in contrast to the ordinary heat transfer due to contact between 5 gas and solid artlcles, and the fluidi~ing medium ls well agitated so that the heat transfer within the grains of the fluldizlng medlu~ may be negllgible. ~n general, the heat transfer cannot be di~regarded in the cas~ where the medium is stationary. Ther~efore, quite substantlal heat ~ransfer 10 characteristics may be obtained. Accordingly, in the thermal energy recovery chamber according to the present invention, it is possible to obtain a large heat transfer coefflcient almost equal to flve times of the conventional incineratlng gas boiler.
As e~plained abovle, the heat transfer phenomenon that occur~ between tha fluldlzin~ medium and the heat transfer ~urfaces largely depends on the strength or weakness o~ the fluid~zation, and the amount of circulating fluidizing medium 20 can be controlled by regulatlng the amount of ga~ introduced from the air diffuser 22. ~180, by arranglng the thermal energy recovery chamber 19 with its moving bed to be independent from the primary incinerating chamber within the incinlerator, it i~ possible to construct a compact thermal 25 energy recovery apparatus in which the turning down ratio is large and the fluidized bed may ~e easily controlled.
As mlentloned above, heat generat2d in the incinerating chamber i~ recovered by the he~t transfer tubes 4 ~5 ~ 20~7~
in the thermal energy recovery chamber 19 to thus generate steam. The isteam turblne 5 18 driven by th~ steam and the generator coupled thereto is driven to generate electricity (see FIG. 1).
On the other hand, the e~haust gas ls di~charged ~rom the upper portion of the boiler and passes through the multistage dust coll~ctor 8, and *hen the exhaust ga~ drives the gas turbine 9. ~he gas turbine 9 drives the co~pre~sor 3 and the generator to thus generate electrlcity.
Particles including ash, char, lime or the like are returned to the free board of the combustor 2 and recirculated in the incinerating chamber.
The NOx content and smoke dust in the exhaust gas emitted from the outlet of the gas turblne 9 are reduced, if 15 necessary. The waste heat of the exhaust ga i5 then recovered by the economizer 7. Thereafter, the e~hau t gas is discharged from the smoke stack 10.
Boilers whlch employ a fuel -~uch a~ coal or petro coke that ls combusted at a low ¢ombustion rate are often able 20 to vary the amount of steam only at a rate commensurate with the combustion rate even though quicker variatlon of th~ amount of steam ~ 8 desirable. In this regard, bubbling boilers are less capable than such boiler~ because they recover thermal energy through the temperature of the fluidized bed.
According to the present invention, however, the amount of heat transferred in the thermal energy recovery cham~er can instantaneously be made s~veral times larger or smaller by varyin~ the amount of alr diffused into the thermal ~6 r~ ~
~ 20~7~8~;
energy recovery chamber. Though varyin~ the amount oP heat generated in the fluidlzed bed by varylng the amount of fuel supplied thereto 5uf fers a time lag a~ it i8 governed by the combustlon rate, the amount of thermal energy recovered from 5 the fluidizing medium in the thermal energy recovery chamber can quickly be varied by controlling the amount of alr diifused into the thermal energy recovery cha~ber. The difference between the response rate~ of changes in the amount of heat ~enerated in the fluidized bed and the anount of thermal energy 10 recovered from the fluidizing medium can be absorbed as a temporary change in the temperature of ~he fluidizing medium by the sensible heat ~torage ability of the fluidizing medium which forms the fluidized bed. Co~sequently, the pressurized internal circulating fluidized-bed boiler accordlng to the 15 present invention can utilize thermal energy without was~lng it, and ls capable of controlllng the amount of steam with a good response which conventional coal-burning boilers have failed to accompllsh.
The fluldlzing alr diffusion device 12 is shown as 20 being of the roof-shaped ~tructure in FIG. 3. Since, howevPr, swirling flows can be created ln the primary incineratlng chamber by the inclined partition ~all if the amount of fluidizing air ejected from th~ nozzle~ 12n of the slde portions A, C of the fluidizln~ air diffusion device 12 is 4 25 Gmf or more, the fluidizing air difusion device 12 may extend horizontally when burnlng combustibles such as coal with a small incombu tible content.
Tha pressurized lnternal circulating fluidized-bed 2~7~86 boiler accordlng to the present invention, therefore, ha~ a hlgh thermal energy recovery capabillty. A process of controlling the pressurized lnternal circulating $1uidized-bed boiler according to the present inventlon will be desaribed 5 below.
According to the present invention, the amount of thermal energy recovered in the thermal energy recove~y chamber is controlled by controlling the amount o a g3~ or air e~ected from the air dlffuser into the thermal energy recovery chamber, 10 and the temperature in the primary ~nclnerating chamber i8 controlled by controlling the amount of charged fuel based on the temperature in the prlmary incinerating chamber or the pressure of steam. Inasmuch as the pressurized internal circulatlng fluidized-~ed boller ~llows the thermal tra~sfer 15 coefficient to b~ adJusted a~ desired and a change in the amount of reaovered ~thermal energy can be absorbed a~ a change in the sensible heat of the fluidizing medlu~, the pressurized internal clrculating fluidiz~d-bed boiler can respond immediat~ly to a change in the load and hence can o~erate 20 stably.
As shown in FIG. 3, if the temperature of steam drawn from the heat transfer tu~es 4 18 insuficient, then a valve 43 on the condult 21 coupled to the air diffuser 22 is opened by a valve opPning controller 42 based on the teDperature detected 25 by a temperature detector 41 on a stea~ outlet pipe 40 connected to the heat transfer tubes 4. Thus, the amount of air dlfused tnto the thermal energy recovery chamber 19 ls i~creased to increase the amount of recovered thermal energy ~-" 2~7~86 for ral~ing the ~team temperature up to a temperature correspondlng to a load that the b~iler 18 required to bear.
The temperature of the fluidlzed bed is detected by a temperature sensor 44. Based on the temperature detected by 5 the temperature sensor 44, the amount of fuel supplied into the primary incinerating chamber and/or the amount of air supplled to the nozzle~ 12n i8 controll~d to control the temp~rature ln the primary lncineratlng chamber within a predet~r~ined range.
Alternatlvely, ~ince when the amount of steam 10 required varies due to a chan~e in the load, the pressure of steam varies mostly quickly ln response to the amount of steam, the amount of fuel supplied to the primary incinerating chamber can be controlled according to a pressure signal lndicative of the pressure of steam.
The responsa characteristics of the boiler at the time the amount of ~team varled ~tepwise from 100 % to 65 % are shown in FIGS. ~ and 10.
FIG. 9 show~ the amount of ~team and the pressure of steam as they vary, and FIG. 10 show the temperature of the 20 fluidized bed a~ it varies. A~ can be seen from FIG. 9, the amount of steam varied qulckly, i~e., varied from 100 ~ o the load to 75 ~ of thQ load in about 1 minute, and became stable as a whole in 3 minutes and 40 second During this tlme, the pressure of steam only vari~d within a range of from ~ 0.1 to -0.3 kg/cm2. The temperature of the fluidlzed bed only variedln a range of f:rom + 11C to - 3~C, and became sta~le at + 4~C
in about 20 minute~ a3 shown in FIG. 10. The graphs of FIGS.
9 and 10 indicate that the control pro~ess according to the f~
7~6 present invention ls qulck ln response and stable ln control.
FIG. 11 illustrates the rasponse characterl~tics of tha boiler at the time the amount of æteam varied stepwise from 100 % to 55 ~ to 30 % to 55 %. Study of FIG. 11 also indicates 5 that the control proce~s al~o achieve~ quic~ response and stable control.
The present invention offers various advantages as described below.
Since the inclnerating c~hamber and the thermal energy 10 racovery chamber are functionally separated from each othsr within *he combustor, the boiler can be controlled to meet a load simply by varying the overall heat transfer coefficient o the heat tran~er tubes through ad~ustment of tha amount of air introduced lnto the thermal energy recovery chamber, rather 15 than by varying the height of the fluidized bed in the incineratlng chamber. Therefora, no complex process and equipment, iOe., a bed material ctora~e container, is necessary to take the fluidizing msdium into and out of the incinerating chamber and the thermal energy recove~y chamber, and no 20 agglomeration is g~nerated as the fluidizing medium flow~ into and out of the incinerating chamber and the thermal energy recovery chamber. Since the temperature o the fluidized bed i5 kept at a constant level even when the load on the boilar varie~, the boiler can be operated under a temperature 25 conditlon optimum for the suppres~ion of NOx, SOx, and other undesirable smissio~. Inasmuch as the heat transfer tubes ara positioned only in the therm~l anergy recovery chamber in whi~h thara exists a gradual 1OW of the fluidlzlng medium, the heat f~
" 20~7~8~
transfer tube~ are less subJect to wear than would be if they were placed in the fluldlzed bed which is in a vlolent flow condltion.
As swirling flow~ are developed in the fluidized bed, S the fluidizing medium does not ~tay stagn~nt in th~ fluidized bed, and the fuel such a~ coal, petro coke, or the like ls unlformly dispersed and combusted, with no agglomeration produced. Th~ amount of carbon monoxide produced is kept low because the exhaust gas emitted from the fluidized bed is not 10 cooled by the heat transer tubes in the fluidized bed. The boiler lends itself to a wide variety of different coal types because it is expected to have a high c~mbustion efficiency with respect to coals with a hlgh ~uel ratio~ The process oi charging a fuel such as coal into the incinerating chamber may 15 be simpllfied a~ the charged coal i~ quickly disparsed.
The denitrification unit may be dispensed with lf ash, char, fine llme partlcle8 or the llke coll~cted from the exhaust ga emittsd from the outlet of the combustor are returned to a free board section of the combustor.
20 Furthermore, lime~tone employed for desulfurization ln the combustor can b~ utilized at a high utilization ratio for a high desulfurization rate.
system shown ln FIG. 15 i8 controlled to meet a load lmposed thereon by varying the helght of the fluldlzed bed ln the combustor 31. More ~peclfically, the fluidizing medium i8 , drawn from the cQmbustor 31 into the bed material storage 5 container 33 to expose heat transfer surfaces of the heat transfer tube 34, thereby controlling the heat generation to meet the load. When the heat transfer surfaces of the heat transfer tube 34 are ~xposed, the heat tran~fer coefficient - thereof is lowered, and hence the amount of heat recovered i~
10 lowered. Since the exhaust gas emitted from the fluidized bed is cooled by the exposed heat transfer ~urfaces, the temperature of the exhaust gas supplied to the ga~ turbine 37 is lowered, thus reducing the output energy of the gas turbine 37. However, the above control proces~ i~ dlsadvantageous in 15 t~at the bed matsrial storage container 33 1~ nece.qsary to with~raw and return the high-temperature flu~dizing medium from and into the combustor 31, it ls not easy to withdraw and return the fluldizing medium at high temperature and pressure, and agglomeration tends to occur when the 1uidi~ing medium 20 partlcles of high heat density are taken in~o and out of the bed material storage container 33.
Furthermore, ~ince the pres~urized flu~dized-bed boilar is under pressure, the heat transfer tube 34 in a splash zone of the fluldized bed is more sub~ect to ~ear than that in 25 thP atmospheric fluldized~bed boilers. Anot~r problem ls that an large amount of carbon monoxide is produced because the exhaust ~as emitted from the fluidized bed ~s cooled by the heat transfer tube 34 and the e~haust gas remains in the r~, 20~7~8~
fluidized bed for a short period of time a8 the helght of the fluidlzed bed 18 reduced.
As described above, l:Lmestone i8 mixed with the fluldizing medium for desulfurization ln the conventional 5 pressurized fluidized-bed electric generating ~ystem shown in FIG. 15. However, the lime~tone wears rapidly, and is scattered as ash from the dust collector 36 wlthout sufficiently contributing to the desulfurizlng action. The conventional pressurized fluidlzed-bed electric generating lO system fails to achieve a high de~ulfurizatlon rate that are required by thermal power plants. If the de~ulfurization rate is increased, then the conventional pressurized fluldized bed electric generating system produces a vast amount o~ scattered ash.
SUMMARY OF THE INV~NTION
It ls therefore an ob~ect of the present invention to provide a pressurized internal circulat~ng fluidized-bed boller ~or a combined-cycle electric generating syste~ 9 which can be controlled to meet a load without varying the height of a 20 fluidized bed, minimizes the ~eneratton of agglomeration and carbon monoxide, and can increase a limestone utilization ratio and a desulfurization rate.
According to the present ~nvention, there is provided 25 a pressurized internal clrculat~ng fluidized-bed boiler for use in a combined-cycle electric generating system, comprising: a pressure vessel: a aombustor disposed ln sa~d pressure vessel;
a primary fluidized bed incinerating chamber having an air ~ 20~7~
diffusion device provided at the bottom of ~aid combustor and adapted to inJect fluidizl~ air upwardly under a mas~ flow that is at least greater at one side than that at another side;
an inclined partition wall provided above a portion of said air 5 diffusion device where the mas~ flow is greater so as to interfere with the upward flow of the flu~dizing air and thereby to deflect the air towards a portion above sald another side of ~aid air diffusion devic:e where the mass flow is imaller; a thermal energy recovery chamber partitioned from 10 said lncinerating chamber by sald incllned partition wall; a heat transfer surace means provided in said thermal energy recovery chamber for a passage of a heat receiving fluid therethrough, and an air diffuser provided at a lower portion of said thermal energy rPcovery chamber; wherein said 15 thermal energy recovery chamber 1s communicated at upper and lower portions thereof with said pri~ary fluidized bed incinerating chamber, a moving bed i8 for~ed above the portlon of said air diffusion device where the in~ected mass flow l~i smaller so that a fluidizing medium descends and diffuses 20 within the moving bed, and a circulating fluidlzed bed is formed abovP the portion of said alr diffusion devlce where the mass flow of the fluidizing alr i8 greater ~o that sai~
~luidlzing med~um is actively fluidized and whirled towardi a position above said moving bed and a part of siaid fluldiz~ng 25 medium is introduced lnto said thermal energy recovery chamber beyond an upper portion of said lnclined partitlon wall, the format~on of said moving bed and said circulating fluld~zed bed is effected by reyulation of the amo~nt of air in~ected 20~ l8~i .
upwardly from said air diffusion devlce and regulation of the fluidlzing air lnJected from said air diffuser in said thermal energy recovery chamber causes the fluidizing medlum wlthin said recovery chamb~r to descend in a state of a moving bed for 5 clrculation.
With the above arrangement of the present inventlon, since the incinerating chamber and the thermal energy recovery chamber are functionally ~eparated from each other within the combustor, the boiler ¢an be controlled to ~eet a load simply 10 by varying the overall heat transfer coefficlent of the heat transfer tubes through ad~ustment of the amount of alr ~ntroduced into the thermal energy recovery chamber, rather than by varying the height of the fluidized bed in the lncinerating chamber. Therefore, no complex process and 15 equipment is necessary to take the fluidizing medium into and out of the incinerating chamber and the ther~al energy recovery chamber, and no agglomeration is generated ~8 the fluidiz~ng medium flows into and out of the incinerating chamber and the thermal energy recovery chamber. Since the temperature of the 20 fluidized bed i8 kept at a constant level even when the load on ~he boiler varies, the boiler can be operated under a temperature condition opt~mum for the suppression of NOx, SOx, and other undesirable emission~. Inasmuch as the heat transfer tubes are positioned only in the thermal energy recovery 25 chamber whioh is exposed to a gradual flow of the fluid~zing medium, tha heat transfer tu~es are less sub~ect to wear than would be if they were placed in the fluidized bed which is in a v~olent flow conditlon.
l rl 8 ~ ~
As swlrllng flows are developed ln the fluidized bed, the fluldizing medlum does not stay stagnant in the fluidlzed bed, and the fuel such as coal or petro coke i5 uniformly dispersed and combusted, with no agglomeration produced. The 5 amount of carbon monoxidei produced is kept low becauie the exhau~t gas emitted from the fluldized bed i8 not cooled by the heat transfer tubeqi in the fluldlzed bed.
The above and other ob~ert3, features, and advantages of the present invention will become apparent from the 10 following description when taken ~n con~unction with the accompanying drawings which illustrate preferred embodiments of the present invention by way of example3.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. l 1i5 a schematic view of a comblned-cycle 15 electrlc generatlng system which lncorporates a pressurized internal circulating fluidized-bed boiler according to an embodiment of the present invention;
FIG. 2 ls a cross-~ectional view o the pressurlzed internal circulatlng fluldlzed-beid boiler;.
FIG. 3 is a cross-sec~ional view showing the detailed structure of the pressurized internal circulating fluid~zed-bed boiler FIG. 4 isi a graph show~ng the relationship between the amount of alr for fluidization (Gmf3 at the portion below 25 the incllned partition wall in the primary fluidized bed lncinerating chamber and the amount o the fluidiziny medium circulated;
FIG. 5 is a graph showing the relationshlp between : ~0~788~
. ~.`
ths amount of diffusing air (Gmf) in the thermal energy recovery chambar and the de~cending rate of the downward movlng bed in the thermal energy recovery chamber;
FIG. 6 is a graph ~howing the relationship between 5 the mass ~low for fluidization (Gmf) and the overall heat transfer coefficient in the conventlonal bubbling type boiler;
FIG. 7 is a graph showing the relatlon~hip between the dlffusio~ mas~ flow (Gmf~ in the thermal energy recovery chamber and the overall heat transfer coefficlent ln the 10 pressurized internal circulating fluidized-bed boller according to the present invention;
FIG. 8 is a graph showlng the relationshlp between the mass flow for fluidization and the abrasion rate of the heat transf~r tube;
FIG. 9 i~ a graph showing varlations relative to the lapse of time in the steam amount and stea~ pressure in respons~ to stepwise ahange of the steam flow rate;
FIG. 10 1~ a graph showing variation~ relative to the lapse of time in temperature o~ th~ fluidized bed;
FIG~ 11 shows simllar varlation~ relative to the lapse of time in response to continuously stepwise change of the steam flow rats;
FIG. 12 show~ a fl~idizing pattern in the primary fluidized bed incineratin~ chamber with the relationship 25 between the horizontal length L of the incinerator bottom and the proJectlon length of the inclined partltion wall in the horizontal direction;
FIG. 13 shows a fluidizing pattern in the primary 9 ~.
209'^~88~
fluidized bed incineratlng chamber with the relatlonshlp between the horizontal length L of the lncinerator bottom and the pro~ection length of the incllned partition wall ln the horizontal directlon;
FIG. 14 show~ a fluidlzing pattern in the primary fluidized bed incinerating chamber with the relationship between the horizontal length L of the incinerator bottom and the proJection length of the incltned partition wall in the horizontal d~rectlon; and FIG. 15 ls a schematic view of a conventional combined-cycle electrlc generating system which incorporateis a pressurized ~iluidized-bed bo~ler.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
FIG. 1 ~chematically showY a combined-cycle electric 15 generatln0 syste~ which incorporates a pressurized lnternal circul~ting fluidized-beid boller according to the presen~
lnvention. As shown in FIG. 1, the combined-cycle electric generating ~yste~ include~ a pressure ve~el 1 houcing a combustor 2 therein. The preis3ure vessel `l communtcates with 20 a compressor 3 which keeps a predetermined prsssure in the pressure ves~el 1. The combustor 2 accom~odates heat transer tubes 4 connected to an inlet of a steam turbine 5 whose outlet is coupled to the hcat transfer tubes 4 through a oondenser 6 and an economizer 7. The heat transfer tubes 4, the steam 25 turbine 5, the conden~er 6, and the economizer 7 Jointly constitute a steiam cycle system.
An ~xhaust gas i~ di~charged from an upper end of the combustor 2 and lntroduced into a gas turbine 9 through a 788~j multistage dust collector 8. The exhaust gas discharged from the gas turblne 9 ls ~upplied to an economizer 7 for heat recovery, and then discharged from a smoke stack 10. Ash, char, fine lime particle~ or the like collected by the first 5 stage of the dust collector 8 are returned to a free board sectlon of the combustor 2.
The pressurized lnternal circulating fluidized-bed boiler wlll be describ~d in detail below with reference to FIGS. 2 and 3.
As shown i~ FIG. 3, the combustor 2 houses a fluidizing air diffuslon device 12 composed of a horizontal array of fluidizing air nozzles 12n on the bottom of the combustor 2. The fluidi~ing air diffusion device 12 has oppo~ite slde portions A, C lower than a csntral portion B
15 thereof. These slde and central portio~ A, B, C are ~ointly of a roof shape which ls s~mmetrical with respect to a vertical central axis of the combustor 2. Fluidizing air is supplied from the compressor 3 through a fluidizing alr conduit 21 to the fluidizing alr nozzle3 12n, from which the fluidizing air 20 is e~ected upwardly lnto the combustor 2. The ma s flow of the fluidiziny air e~ected from the air nozzles 12n of the side portions A, C of the fluidizing air diffusion device 12 is a speed high enou~h to for~ a fluidized bPd of a fluidizing medium in the combustor 2. The mass flow of the fluldizing air-~5 ejected from the air nozzles 12n of the central portion B ofthe fluidizing air diffuslon device 12 i8 smaller than the mass flow of the fluidizlng alr e~ected from the air nozzles 12n of ~h~ side portions A, C of the fluldizlny air diffuslon device ,; , . . . .
~ 2~7:~8~
12.
A partltlon wall 18 i9 dispo~ecl slightly above the respec~lve oppo~ite end~ of the fluldiz$~g air diffu~ion device 12. The partitlon wall 18 define a primary incineratlng 5 chamber in the combustor 2. The partition wall 18 comprlses a vertical partition wall 18a and an inclined partition wall 18b.
The inclined partition wall 18b se:~es as a reflective wall for r~flectlng the flu~z~ng air eJec:ted from the air nozzles 12n of the side portions A, C toward the center of the combustor 2.
10 Because of the lnclined partition wall 18b and the difference between the mass flows of the e~ected fluldizing air, swirling flows of the fluidizing medium aIe developed in the combustor 2 as indlcated ~y the arrows in FIG. 3. A thermal energy .recovery chamber 19 15 defined bet~een the back of the 15 partition wall 18 and the wall of the combu~tor 2. Whlle the combu3tor 2 18 in operation, a part of the fluidizing medlum flow over the upper ed~e of the inclined partition wall 18b into the thermal ener~y recovery chiamber 19. ~he heat transfer tubes 4 are disposed ln the thermal energy recovery chamber 1 20 for recovering thermal energy from the fluidizing medlum flowing downwardly ln the thermal energy recovery chamber 19 through a heat exchange wlth the fluidizlng m~dium.
The lnclined partition wall 18b ~s inclined to the horizontal planie by an angle in the range of from 10~ to 60, ~5 preferably 25 to 45~ The horizontal len~th 1 of the ~nclined partition wall 18b as ~t i pro~ected onto the bottom of the lncinerator i~iln the range of from 1/6 to 1/2, preferably from 1/4 to 1/2, of the horizontal length L of the bottom of the :
~ 2~78~
incinerator.
The angle of inclination of the inclined partition wall 18b to the horlzontal plane and the horizontal length l of the inclined partition wall 18b a~ lt is projected onto the 5 bottom of the incinerator affect the fluidized state of the fluidizing medium in the primary lncinerating chamber in the incinerator and the amount of particles that enter the thermal energy recovery chamber 19. The ]Length~ ~, 1 and the flow of the fluidizing medium are shown in FIG. 120 If the angle of inclinat:Lon of the inclined partition wall 18b to the horizontal plane were smaller than 10 or larger than 60, then no good swirlin~ flows would be created, and the fuel such as coal would not be combusted well. The angle of inclination o~ the lnclined partition wall 18b to the 15 horlzontal plane should preferably be in the range of from 25 to 45, and more preferably be about 35.
If the horlzontal length l of the inclined partition wall 18b as it ls pro~cted onto the bottom of the ~ncinerator were yreater than 1/2 of the horizontal length L of the bottom ~0 of the lncinerator, then the fluidizing medium reflected back by the inclined partition wall 18b would be blown up as shown in FIG. 13. Since the fuel would also be blown up, the fuel charged in the prlmary i~clnerating chamber would not be burned effectively.
If the horlzontal length l of the inclined partitlon wall 18b as lt 18 projected onto the bottom of the lnoinerator were smaller than 1/6 of the horizontal length L of the bottom of the incinerator, then the ~wirling 10ws of the fluid~zing 20978~fi medium in the primary incineratlng chamber would be deteriorated, and the moving bed ln the central region of the inainerator would not be formed suffiGiently. The uel entraining and diffusing effect would be iDpalred, and the 5 fluidizing medium would not sufficiently b~ deflected into the thermal energy recovery chamber 19.
An air diffuser 22 ls disposed ln a lower portion of ~he thermal energy recovery chamber 19 for introducing a gas or air from the compressor 3 through a condu$t 21 into the thermal 10 energy recovery chamber 19. As shown ln FIG. 3, the air diffuser 22 comprises an inclined plate 23 havlng an array of nozzles 23n, the inclined plate 23 being progressively inclined outwardly toward the wall of the combustor 2. An opening 24 is defined near the air diffuser 22 vertically between the lower 15 end of the partltion wall 18 and the inner end of the alr di~fuser ~2. The fluidizing medlum tha* ha~ entered the thermal energy recovery chamber 19 descends therein while forming a moviny bed continuously or inter~ittently depending on the operat~ng condition of the boiler, and is circulated 20 through the opening 24 lnto the primary incinerating chamber.
Another alr diffu er 29 ls mounted on the bac~ of the inclined partition wall 18b ln an upper portion of the thermal energy recovery chamber 19. ~he air difuser 2~ e~ects air to blow, combust, agltate, and diffuse the coal that has entered 25 the thermal energy recovery chamber 19. No heat tr nsfer tubes are located ln the vicinity of the air diffuser 29, l.e., the air diffuser 29 i positioned remotely fro~ the heat transfer tubes 4.
2 ~ 9 7 ~
The descending amount of the fluidizing medlum in the thermal energy recovery chamber 19 for clrculatlng i~ regulated by the amount of diffuslng air for the then~al energy recovery chamber and the amount o fluidizing air for the incinerating 5 portion. That ~, the amount of fluidizing mediu~ (G1) introduced into the terminal en~rgy recovery chamber 19 is increased 2~ shown in FIG. 4 when the ~mount oP fluidizing air in~ected from the air diffu~lon device 12, particularly the amount of fluidizing a~r ln~ected :Erom the nozzles 12n disposed 10 on both s~de portion~ A, C i~ increased. Further, as shown in FIG. 5, the amount of fluidlzing medlum descendlng in the thermal energy recovery chamber 19 is approximately proportionally changed with respect to the change ln the amount of dlffuslng air blown into the thermal energy recovery chamber 15 19 when the amount of diffu~ing alr for the thermal energy recovery chamber is in the range of 0-1 Gmf. The amount of fluldizing medium descendi~g in the th~rmal energy recovery chamber 19 becomes approximately constant when the amount of diffusing air for the thermal energy recovery chamber is beyond 20 1 Gmf. This constant amount of fluldizlng medium is almost equivalent to the amount of fluidizing medium (Gl) introduced into the thermal energy recovery chamber and thu~ the amount of fluidizing medium descendlng in the thsrmal energy recov~ry chamber becomes equivalent to a value corresponding to G~. By 25 controlling the air amount both for the incinerating portion and the recovery chamber, the descending amount of fluidizing medium ln the thermal energy recovery chamber 19 may be regulated.
2~8~
The descent of the fluidizing medium in the static bed in the range of 0-1 Gmf depend~ on the weight d~fference (the difference in hslght of the fluidized beds) between the fluidizing medium in th~ thermal enS2r9y recovery chamber and 5 the fluidizing medium in the prlmary fluidizesd bed incineratlng chamber. In the case where the mas~ flow ls over 1 Gmf, the height of the moving bed portion becomes slightly h~gher or appro~imately equal to the other.
The clrculating of the fluidiztng medium i~ asslsted 10 by a deflecting flow with a sufficls~nt amount of fluidizing medium caused by the inclined part1tion wall.
Now, the relationship between ths~ height of the fluid~zed bed and the circulating amount of the fluidizlng mediums (the deflecting ~low) wlll S~e explained in detail.
In the case where the surace of the fluidized bed i~
lower than the upper end oP the inclined partition wall, the air flow movin~ upwardly along the inclined partition wall is given lts direction by the incllnad partition wall, flow~ along the inclined partition wall and i~ in~ected from the flu~dized 20 bsd, whereby the fluidizing medium is accompanied therewith.
The inJected alr flow is put in a ~tate different from that in the fluidized bed and freed from the fluidizing medium with which the fluidized bed 1~ filled. Thereafter the sectional area of the air flowin~ passage is ~uddenly Rnlarged, the 25 in~ected air flow is dlffused and reduce~ its ~peed to a few mJs to thus become a gentle flow, and is discharged upwardly~
Therefore, the fluldizing medium accompanied by the inJected alr flow lose~ its kinetic energy and falls downwardly due to 2 ~
gravity and the frictlon wlth the exhaust ga~ as the grain size of the fluldlzing medium i8 too large (approximately 1 mm) to be carried with the air flow.
In the case where the ~urPace of the fluidizing bed 5 i~ higher than the upper end of the inclln0d partition wall, a part of the fluldizing air gathered by the partition walls is in~ected along thei deflecti~g partltlon wall toward a certain direction in such a manner similar to that in the circulating fluidized bed inclnerator, whilteti the other part, due to a 10 sudden boiling phenomenon derived from the explosion of bubbles, i3 boiled upwardly like flre works ~uist abovt2 the upper end of the incllned partition wall and falls over all around the periphery. Accordingly, a part of the fluidizing medium is introduced ln a large amount lnto the bacl~ side of 15 ths partition wall, i.e. the thermal energy recovery chamber.
That i8, the ~ov~ng direction of the ln~ected fluidizlng ~nedium becomes closer to upright ais the surface of the fluldizlng bed becomes higher than the upper end of the inclined partitlon wall. Therefore, the amount of iEluidizing 20 medium introduced into the thermal energy recovery chamber becomes larger ln the case where the surface of the fluidizlng bed i~ slit3htly above the upper end of the inclined ~artition wall .
FIG. 4 shows the relationship between the amount of 25 fluidizing air in thP portion below the inclined partition wall in the primary fluidizing bed incinerating chamhter and the amount of fluidizing medium circulatt2d through the thermal energy retticov~ry chamher 209 ~88~
For example, durlng the operatlon und~r the ~tate Ll, lf the helght of the fluidlzed bed ls lowered due to the scattering of the abraded ~luidizing medium, the circulating amount of ~he fluidizing medlum i8 suddenly reduced to, for 5 example, helow 1/10 of that of the former and thermal energy recovery cannot be performed. Thus, what is important ls the amount of the fluidizing air and, ln the ca~e where it ls arranged to be more than 4 Gmf and preferably ~ore than 6 Gmf, the value of G1/Go is malntained over 1 and the required and 10 sufficient amount of the circulating fluidizing medium may be obtained even if the height of the fluidized bed is changed.
Further, by arranging the mass flow of the air in~ected Prom the air diffuser 22 in the bottom of the thermal energy recovery chamber to be 0-3 Gmf, or preferably 0~2 Gmf, 15 and the mas~ flow of the fluldizing air in~cted from the air diffusion device 12 dl~posed below the inçlin~d partition wall to be 4-20 Gmf or preferably 6-12 Gmf, that i~, by always keeplng the ma~s flow to be larger at the incin~ra~ing chamber side than at the thermal energy recovery chamber side, the 20 amount of fluidlzing medium fed back to the primary fluidized bed incinerating chamber from the thermal energy recovery chamber may ~e regulated.
As to the moving bed in the thermal energy recovery chamber, lt is referred to in the aeade~ic sense as a static 25 bed when the mass flow i~ 0-1 Gmf and a fluidized bed when the mass flow is ovar 1 Gmf, and it is co~monly known that a minimum mas~ flow of 2 Gmf i8 required to form a stable fluidtzed bed. On the other hand, in the case of the moving 209~86 bed accordlng to the present invention, whlch ls always d~scendin~ and movlng, the de~cending moving bed 18 satisfactorily formed untll the mass flow is increased up to the order of about 1.5-2 Gmf without causing the destruction of 5 the moving bed by the bubbling phenomen~n. Xt ls assumed that the grains of the fluidlz$ng medlum gradually de~cend and move under a vibratlng mode whereby the fluidi~ing air is converted into small alr bubbles uniformly flowing upward towards the upper portion of the moving bed.
The heat transfer coeff:Lcien~ in the thermal energy recovering portion i8 greatly varled as shown in FIG. 7 when the amount of the diffusing air ln the thermal energy recovery chamber is changed ln the rang2 of 0-2 Gmf.
Now the characterl~tics such as the load response 15 characteristlcs caused by the formation o~ the moving bed in the thermal energy recovery chamber will be explained.
The general relationship b~ween the overall heat transf~r coefflcient and the mas~ flow for fluldization is shown in FIG. 60 Between the values of the mass flow in the 20 range of 0-1 Gmf, the increase in the heat transfer coefficient is small. The heat transfer coefficient su~denly increases when the mass flow becomes over 1 Gmf. As a method for turning down the fluldized bed boiler utilizlng the above phenomeno~, the "Wing Panel Type" i~ disclosed in DOE Report, 6021 (2)~
25 655-663 (1~85) and the heat transfer coefflcient in response to the variation of the flu~dizing mass flow is descrlbed to be insensitive (s~atic bed) or too sensitive (fluidized bed).
Incldentally, upon revlewing certain fore~gn patent 2~7~
speclfications, several cases are found which seem to be slmilar to tha present technology in the point that the inclneratlng chamber and the thermal ~nergy recovery chamber are separated. However, all the partitions disclosed therein 5 are provided in a vertical direction, and the flu~dizing medium in the thermal energy recovery ch~ber is ln the mode for being changed to the static bed and to the fluidizing bed, it being the ~tatic bed when the thermal energy recovery ls small in amount and the fluidlzing bed in which the medium ls blown 10 upwardly from the lower portion when the thermal energy recovery is large ln amount. This is because lt is difficult to produce a deflected flow with a vertically oriented partition a~ compared to the case where the partition ls inclined. It 13 therefore inevitable in the vertically 15 oriented partit~n that the fluidizing medlum i~ arra~ged in both the i~cineratin~ chamb~r and the ther~al energy recovery chamber to be in a fluidized state (simll~r to water) 80 ~hat the fluidizing medium ls caused to flow between the two chamber~.
The relationsh~p between the overall heat transfer coefficient and the mass flow for fluidlzation is shown in FIG.
7. As shown in FIG. 7, the overall heat transfer coefficient changes almost linearly and, thu~, the amount of thermal energy recovered and the temperature of the pri~ary fluidlzed bed 25 lncinerating chamber may be controlled opt~onally. Further, such control may be easily efscted simply by regulating the amount of diffusing alr in the thermal energy recovery chamber.
Further, it ls sald that the abr~sion rate of the 20~7886 heat transfer tubes in the fluidized bed i8 ~roportlonal to the cube of the mas~ flow for fluldlzation and such relationship is Yhown in FIG. 8. Accordingly, the problem of abrasion regarding the heat transfer tube~ may be ~olved by arranging 5 the amount of dlffusing air blown into the moving bed in the thermal energy recovery chamber to 0-3 Gmf or preferably 0-2 Gmf.
In order to regulate the amount of thermal energy recovered, regulation of the amount of circulatlng fluidizing 10 medium i~ effected, as explained before, while e~fecting simultaneous regulation o the heat transfer co~fficient. That is, in the case where the amount of diffusing air in the thermal energy recoveir~ chamber is increased, the amount of circulating fluidizing medium i~ increased and the heat 15 transfer coefficlent 1~ ~imultaneously incr~ased to greatly increase the amount of thermal energy recovered by synergistic effect of the two ~actors~ From the viewpoint of the temperature of the fluidi~ng medium in the fluidized bed, the above corr~sponds to the effect of preventing the temperature 20 of the fluidizlng mediu~ from ~eing raised above the predetermined temperature.
As a means for introducing the dlffusing air into the thermal energy recovery chamber 19, several means may be considered, but it is generally di pos~d on thR bottom of the 25 thermal enerjgy recovery chamber 19 so as to effectively utillze the space in the thermal energy reco~ery chamber.
Further, ln the alr diffu~er 22, tha dlffusing air from the nozzles 23n ~ in~ected toward the incineratin~
~1 2 0 19 7 ~
chamber ~o that the fluldlzing medlum can be ea~lly lntroduced lnto the inclnerating chamber.
~ he respective sizes of the nozzles are preferably determined so that an approximately unifor~ dif~u~ing amount is 5 in~ected over the full length of the air diffuser 22 with the diffusing air amount being 2 Gmf. That i8, wh2n the above is satisfied, it is pos~ible to obtain the maximum amount of thermal energy recovered by all the heat tran~fer surfaces in the thermal energy recovery cham~er and the abra3ion rats of 10 the heat transfer surfaces may be kept small over all the sur:EaceQ .
In FIG. 3, a combustible charge inlet 26 is provided at the upper portion of the lncinerator. Combustibles such as coal or petro coke are ~upplied to the co~bu~tor 2 through the 15 combustible charge inlet 26 by a pneu~atic conveyor (not shown3.
Next, operatlon o~ the pressurized internal circulatlng fluidized-bed boller thus c~n~tructed will be described below.
The combustible~ F charged through th~ combustible charge inlet 26 are circulated and combusted in the $1uidizlng medium which i~ circulated under the influence of the circulatin~ flow caused by the fluidizing air. At this time, the fluid$zing medium at the central portion B above the air diffusisn device 25 12 ~s not accompanied by a violent up-and-down motion thereof and form~ a descending moving bed which is in a weak fluidizing state. The wldth o~ this movln~ bed i~ narrow at the upp~r portion thareof and the trailing ends thereof are extended in 2~78~
the opposite directlons to reach the portions above both slde portlon~ A, C of the air dlffusion devlce 12, thus the fluidizing medium is ~ubJected to the fluldlzlng air in~ected at a greater mas~ flow from ~oth side portion~ A, C and is 5 blown upwardly. Accordingly, a portinn of each trailing end is displaced and, thus, th~ bed ~u~t above the central portion B
descends under gravity. Abo~e thi~ bed, the fluidizing medium pile~ up by being supplemented f`rom the fluidizlng bed, as explained later, and the flu1dizing medium above the air 10 diffusion device 12 forms a gradually and cont~nuously descending moving bed with the repetition of the above modes.
The fluidizing medium moved above both side portions A, C is blown upwardly and deflected and whirled by the inclined partition walls 18b toward~ the center of the 15 incinerator and falls on the top of the central moving bed and i~ circulated again as explained b~fore. A part of the fluidizin~ medlum ls introduced into the thermal energy recovery chambers 19 beyond the upper portions of the inclined partltion wall3 18b. In the cas~ where the descending rate of 20 the fluidizin~ medium in the thermal energy recovery chamber 19 i8 slow, the angle of repose for the fluidizlng medium is formed at the upper portion of the ~hermal energy recovery chamber and the excess fluidizing medium falls from the upper portio~ o~ the inclined partition wall 18b to the primary 25 fluid~zed bed incinerating chamberO
The ~luidizing medium intrnduced into the thermal energy recovery chamb~r 19 forms a gradually descending moving b~d du~ to the ga~ in~ected from the air dluser 22 and it is r~
20~78~6 ., returned to the primary fluidized bed incin~,r~ting chamb~r from the opening portlon 24 after the heat transfer i~ effected with the heat transfer tubes.
The mass flow o~ the diffusing air introduced from 5 the air diffuser 22 ln the thermal energy recovery chamber 19 is selected from values in the range of 0-3 Gmf or preferably 0-2 Gmf.
The reason for the above i8 that, as shown in FIG. 7, the heat transfer coefficlent varies from the minimum to the 10 maximum below the value of 2 Gmf and the abraslon rate can be controlled, as shown in FIG. 8, within a small range.
Further, the thPrmal energy recovery chamber is located outside the ~trong corroslve zone of the primary *luidized bed lncinerating chamber under the reducing 15 atmospheres and, thus, the heat tran~fer tubes 4 are subJected to less corrosion as compared to the conventional one~ and the degree of abrasion of the heat transfer tubes 4 i8 made quite small because the fluidizing ra$e in thi~ section is, as explained beore, low. A~ to the speed of air flow ln the 20 fluidizing air with mass flow ranglng 0-2 ~f, it is 0-0.4m/sec (superficial velocity) at 800~ which i~ quite low while it practically depends on the $emperature and grain size of the fluidi~ng medium.
Regarding the heat transfer in the thermal energy 25 recovery chamber 19, in addition to the heat transfer that takes place dus to the direct contact between the fluidizing medium and ~he heat trans-Eer tube~ 4, there is another form of heat transfer that utilizes the ris~ng gas moving upwardly wlth 2 0 ~ '7 ~ ~ ~
irregular vibration as the fluldlzlng ~edium move~. In the latter case, there 18 substantlally no boundary layer between the solid articles checklng or preventing the heat tran~fer, in contrast to the ordinary heat transfer due to contact between 5 gas and solid artlcles, and the fluidi~ing medium ls well agitated so that the heat transfer within the grains of the fluldizlng medlu~ may be negllgible. ~n general, the heat transfer cannot be di~regarded in the cas~ where the medium is stationary. Ther~efore, quite substantlal heat ~ransfer 10 characteristics may be obtained. Accordingly, in the thermal energy recovery chamber according to the present invention, it is possible to obtain a large heat transfer coefflcient almost equal to flve times of the conventional incineratlng gas boiler.
As e~plained abovle, the heat transfer phenomenon that occur~ between tha fluldlzin~ medium and the heat transfer ~urfaces largely depends on the strength or weakness o~ the fluid~zation, and the amount of circulating fluidizing medium 20 can be controlled by regulatlng the amount of ga~ introduced from the air diffuser 22. ~180, by arranglng the thermal energy recovery chamber 19 with its moving bed to be independent from the primary incinerating chamber within the incinlerator, it i~ possible to construct a compact thermal 25 energy recovery apparatus in which the turning down ratio is large and the fluidized bed may ~e easily controlled.
As mlentloned above, heat generat2d in the incinerating chamber i~ recovered by the he~t transfer tubes 4 ~5 ~ 20~7~
in the thermal energy recovery chamber 19 to thus generate steam. The isteam turblne 5 18 driven by th~ steam and the generator coupled thereto is driven to generate electricity (see FIG. 1).
On the other hand, the e~haust gas ls di~charged ~rom the upper portion of the boiler and passes through the multistage dust coll~ctor 8, and *hen the exhaust ga~ drives the gas turbine 9. ~he gas turbine 9 drives the co~pre~sor 3 and the generator to thus generate electrlcity.
Particles including ash, char, lime or the like are returned to the free board of the combustor 2 and recirculated in the incinerating chamber.
The NOx content and smoke dust in the exhaust gas emitted from the outlet of the gas turblne 9 are reduced, if 15 necessary. The waste heat of the exhaust ga i5 then recovered by the economizer 7. Thereafter, the e~hau t gas is discharged from the smoke stack 10.
Boilers whlch employ a fuel -~uch a~ coal or petro coke that ls combusted at a low ¢ombustion rate are often able 20 to vary the amount of steam only at a rate commensurate with the combustion rate even though quicker variatlon of th~ amount of steam ~ 8 desirable. In this regard, bubbling boilers are less capable than such boiler~ because they recover thermal energy through the temperature of the fluidized bed.
According to the present invention, however, the amount of heat transferred in the thermal energy recovery cham~er can instantaneously be made s~veral times larger or smaller by varyin~ the amount of alr diffused into the thermal ~6 r~ ~
~ 20~7~8~;
energy recovery chamber. Though varyin~ the amount oP heat generated in the fluidlzed bed by varylng the amount of fuel supplied thereto 5uf fers a time lag a~ it i8 governed by the combustlon rate, the amount of thermal energy recovered from 5 the fluidizing medium in the thermal energy recovery chamber can quickly be varied by controlling the amount of alr diifused into the thermal energy recovery cha~ber. The difference between the response rate~ of changes in the amount of heat ~enerated in the fluidized bed and the anount of thermal energy 10 recovered from the fluidizing medium can be absorbed as a temporary change in the temperature of ~he fluidizing medium by the sensible heat ~torage ability of the fluidizing medium which forms the fluidized bed. Co~sequently, the pressurized internal circulating fluidized-bed boiler accordlng to the 15 present invention can utilize thermal energy without was~lng it, and ls capable of controlllng the amount of steam with a good response which conventional coal-burning boilers have failed to accompllsh.
The fluldlzing alr diffusion device 12 is shown as 20 being of the roof-shaped ~tructure in FIG. 3. Since, howevPr, swirling flows can be created ln the primary incineratlng chamber by the inclined partition ~all if the amount of fluidizing air ejected from th~ nozzle~ 12n of the slde portions A, C of the fluidizln~ air diffusion device 12 is 4 25 Gmf or more, the fluidizing air difusion device 12 may extend horizontally when burnlng combustibles such as coal with a small incombu tible content.
Tha pressurized lnternal circulating fluidized-bed 2~7~86 boiler accordlng to the present invention, therefore, ha~ a hlgh thermal energy recovery capabillty. A process of controlling the pressurized lnternal circulating $1uidized-bed boiler according to the present inventlon will be desaribed 5 below.
According to the present invention, the amount of thermal energy recovered in the thermal energy recove~y chamber is controlled by controlling the amount o a g3~ or air e~ected from the air dlffuser into the thermal energy recovery chamber, 10 and the temperature in the primary ~nclnerating chamber i8 controlled by controlling the amount of charged fuel based on the temperature in the prlmary incinerating chamber or the pressure of steam. Inasmuch as the pressurized internal circulatlng fluidized-~ed boller ~llows the thermal tra~sfer 15 coefficient to b~ adJusted a~ desired and a change in the amount of reaovered ~thermal energy can be absorbed a~ a change in the sensible heat of the fluidizing medlu~, the pressurized internal clrculating fluidiz~d-bed boiler can respond immediat~ly to a change in the load and hence can o~erate 20 stably.
As shown in FIG. 3, if the temperature of steam drawn from the heat transfer tu~es 4 18 insuficient, then a valve 43 on the condult 21 coupled to the air diffuser 22 is opened by a valve opPning controller 42 based on the teDperature detected 25 by a temperature detector 41 on a stea~ outlet pipe 40 connected to the heat transfer tubes 4. Thus, the amount of air dlfused tnto the thermal energy recovery chamber 19 ls i~creased to increase the amount of recovered thermal energy ~-" 2~7~86 for ral~ing the ~team temperature up to a temperature correspondlng to a load that the b~iler 18 required to bear.
The temperature of the fluidlzed bed is detected by a temperature sensor 44. Based on the temperature detected by 5 the temperature sensor 44, the amount of fuel supplied into the primary incinerating chamber and/or the amount of air supplled to the nozzle~ 12n i8 controll~d to control the temp~rature ln the primary lncineratlng chamber within a predet~r~ined range.
Alternatlvely, ~ince when the amount of steam 10 required varies due to a chan~e in the load, the pressure of steam varies mostly quickly ln response to the amount of steam, the amount of fuel supplied to the primary incinerating chamber can be controlled according to a pressure signal lndicative of the pressure of steam.
The responsa characteristics of the boiler at the time the amount of ~team varled ~tepwise from 100 % to 65 % are shown in FIGS. ~ and 10.
FIG. 9 show~ the amount of ~team and the pressure of steam as they vary, and FIG. 10 show the temperature of the 20 fluidized bed a~ it varies. A~ can be seen from FIG. 9, the amount of steam varied qulckly, i~e., varied from 100 ~ o the load to 75 ~ of thQ load in about 1 minute, and became stable as a whole in 3 minutes and 40 second During this tlme, the pressure of steam only vari~d within a range of from ~ 0.1 to -0.3 kg/cm2. The temperature of the fluidlzed bed only variedln a range of f:rom + 11C to - 3~C, and became sta~le at + 4~C
in about 20 minute~ a3 shown in FIG. 10. The graphs of FIGS.
9 and 10 indicate that the control pro~ess according to the f~
7~6 present invention ls qulck ln response and stable ln control.
FIG. 11 illustrates the rasponse characterl~tics of tha boiler at the time the amount of æteam varied stepwise from 100 % to 55 ~ to 30 % to 55 %. Study of FIG. 11 also indicates 5 that the control proce~s al~o achieve~ quic~ response and stable control.
The present invention offers various advantages as described below.
Since the inclnerating c~hamber and the thermal energy 10 racovery chamber are functionally separated from each othsr within *he combustor, the boiler can be controlled to meet a load simply by varying the overall heat transfer coefficient o the heat tran~er tubes through ad~ustment of tha amount of air introduced lnto the thermal energy recovery chamber, rather 15 than by varying the height of the fluidized bed in the incineratlng chamber. Therefora, no complex process and equipment, iOe., a bed material ctora~e container, is necessary to take the fluidizing msdium into and out of the incinerating chamber and the thermal energy recove~y chamber, and no 20 agglomeration is g~nerated as the fluidizing medium flow~ into and out of the incinerating chamber and the thermal energy recovery chamber. Since the temperature o the fluidized bed i5 kept at a constant level even when the load on the boilar varie~, the boiler can be operated under a temperature 25 conditlon optimum for the suppres~ion of NOx, SOx, and other undesirable smissio~. Inasmuch as the heat transfer tubes ara positioned only in the therm~l anergy recovery chamber in whi~h thara exists a gradual 1OW of the fluidlzlng medium, the heat f~
" 20~7~8~
transfer tube~ are less subJect to wear than would be if they were placed in the fluldlzed bed which is in a vlolent flow condltion.
As swirling flow~ are developed in the fluidized bed, S the fluidizing medium does not ~tay stagn~nt in th~ fluidized bed, and the fuel such a~ coal, petro coke, or the like ls unlformly dispersed and combusted, with no agglomeration produced. Th~ amount of carbon monoxide produced is kept low because the exhaust gas emitted from the fluidized bed is not 10 cooled by the heat transer tubes in the fluidized bed. The boiler lends itself to a wide variety of different coal types because it is expected to have a high c~mbustion efficiency with respect to coals with a hlgh ~uel ratio~ The process oi charging a fuel such as coal into the incinerating chamber may 15 be simpllfied a~ the charged coal i~ quickly disparsed.
The denitrification unit may be dispensed with lf ash, char, fine llme partlcle8 or the llke coll~cted from the exhaust ga emittsd from the outlet of the combustor are returned to a free board section of the combustor.
20 Furthermore, lime~tone employed for desulfurization ln the combustor can b~ utilized at a high utilization ratio for a high desulfurization rate.
Claims (10)
1. A pressurized internal circulating fluidized-bed boiler for use in a combined-cycle electric generating system, comprising:
a pressure vessel;
a combustor disposed in said pressure vessel;
a primary fluidized bed incinerating chamber having an air diffusion device provided at the bottom of said combustor and adapted to inject fluidizing air upwardly under a mass flow that is at least greater at one side than that at another side;
an inclined partition wall provided above a portion of said air diffusion device where the mass flow is greater so as to interfere with the upward flow of the fluidizing air and thereby to deflect the air towards a portion above said another side of said air diffusion device where the mass flow is smaller;
a thermal energy recovery chamber partitioned from said primary incinerating chamber by said inclined partition wall;
a heat transfer surface means provided in said thermal energy recovery chamber for a passage of a heat receiving fluid therethrough; and an air diffuser provided at a lower portion of said thermal energy recovery chamber;
wherein said thermal energy recovery chamber is communicated at upper and lower portions thereof with said primary fluidized bed incinerating chamber, a moving bed is formed above the portion of said air diffusion device where the injected mass flow is smaller so that a fluidizing medium descends and diffuses within the moving bed, and a circulating fluidized bed is formed above the portion of said air diffusion device where the mass flow of the fluidizing air is greater so that said fluldizing medium is actively fluidized and whirled towards a position above said moving bed and a part of said fluidizing medium is introduced into said thermal energy recovery chamber beyond an upper portion of said inclined partition wall, the formation of said moving bed and said circulating fluidized bed is effected by regulation of the amount of air injected upwardly from said air diffusion device and regulation of the fluidizing air injected from said air diffuser in said thermal energy recovery chamber causes the fluidizing medium within said recovery chamber to descend in a state of a moving bed for circulation.
a pressure vessel;
a combustor disposed in said pressure vessel;
a primary fluidized bed incinerating chamber having an air diffusion device provided at the bottom of said combustor and adapted to inject fluidizing air upwardly under a mass flow that is at least greater at one side than that at another side;
an inclined partition wall provided above a portion of said air diffusion device where the mass flow is greater so as to interfere with the upward flow of the fluidizing air and thereby to deflect the air towards a portion above said another side of said air diffusion device where the mass flow is smaller;
a thermal energy recovery chamber partitioned from said primary incinerating chamber by said inclined partition wall;
a heat transfer surface means provided in said thermal energy recovery chamber for a passage of a heat receiving fluid therethrough; and an air diffuser provided at a lower portion of said thermal energy recovery chamber;
wherein said thermal energy recovery chamber is communicated at upper and lower portions thereof with said primary fluidized bed incinerating chamber, a moving bed is formed above the portion of said air diffusion device where the injected mass flow is smaller so that a fluidizing medium descends and diffuses within the moving bed, and a circulating fluidized bed is formed above the portion of said air diffusion device where the mass flow of the fluidizing air is greater so that said fluldizing medium is actively fluidized and whirled towards a position above said moving bed and a part of said fluidizing medium is introduced into said thermal energy recovery chamber beyond an upper portion of said inclined partition wall, the formation of said moving bed and said circulating fluidized bed is effected by regulation of the amount of air injected upwardly from said air diffusion device and regulation of the fluidizing air injected from said air diffuser in said thermal energy recovery chamber causes the fluidizing medium within said recovery chamber to descend in a state of a moving bed for circulation.
2. The pressurized internal circulating fluidized-bed boiler according to claim 1, further comprising a second air diffuser mounted on said inclined partition wall in an upper portion of said thermal energy recovery chamber, for diffusing air to combust, agitate, and diffuse a fuel that has entered said thermal energy recovery chamber, said second air diffuser being positioned remotely from said heat transfer surface means.
3. The pressurized internal circulating fluidized-bed boiler according to claim 1, wherein said air diffuser is inclined progressively downwardly toward said primary incinerating chamber for directing the fluldizing medium from said thermal energy recovery chamber into said primary incinerating chamber.
4. The pressurized internal circulatinf fluidized-bed boiler according to claim 1, wherein said air diffuser is directed to orient the air toward said primary incinerating chamber for directing the fluidizing medium from said thermal energy recovery chamber into said primary incinerating chamber.
5. The pressurized internal circulating fluidized-bed boiler according to claim 1, further comprising a dust collector for collecting dust particles from an exhaust gas emitted from said combustor and returning the collected dust particles to a free board section of said combustor.
6. The pressurized internal circulating fluidized-bed boiler according to claim 1, wherein said inclined partition wall is inclined by 10°-60° relative to the horizontal and the projection length (1) thereof in the horizontal direction is 1/6-1/2 of the horizontal length (L) of a bottom of the incinerator.
7. The pressurized internal circulating fluidized-bed boiler according to claim 1, wherein the mass flow of the air injected from said air diffuser at the bottom of said thermal energy recovery chamber is in the range of 0-3 Gmf, and the mass flow of the fluidizing air injected from said air diffusion device below said inclined partition wall is in the range of 4-20 Gmf.
8. The pressurized internal circulating fluidized-bed boiler according to claim 1, wherein said inclined partition wall is inclined by 25°-45° relative to the horizontal.
9. The pressurized internal circulating fluidized-bed boiler according to claim 1, wherein said inclined partition wall is inclined by approximately 35° relative to the horizontal.
10. The pressurized internal circulating fluidized-bed boiler according to claim 1, wherein said inclined partition wall is formed such that said projection length (1) in the horizontal direction is 1/4-1/2 of the horizontal length (L) of said bottom of said incinerator.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US08/069,686 US5313913A (en) | 1993-05-28 | 1993-05-28 | Pressurized internal circulating fluidized-bed boiler |
| CA002097886A CA2097886A1 (en) | 1993-05-28 | 1993-06-07 | Pressurized internal circulating fluidized-bed boiler |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US08/069,686 US5313913A (en) | 1993-05-28 | 1993-05-28 | Pressurized internal circulating fluidized-bed boiler |
| CA002097886A CA2097886A1 (en) | 1993-05-28 | 1993-06-07 | Pressurized internal circulating fluidized-bed boiler |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2097886A1 true CA2097886A1 (en) | 1994-12-07 |
Family
ID=25676258
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002097886A Abandoned CA2097886A1 (en) | 1993-05-28 | 1993-06-07 | Pressurized internal circulating fluidized-bed boiler |
Country Status (2)
| Country | Link |
|---|---|
| US (1) | US5313913A (en) |
| CA (1) | CA2097886A1 (en) |
Families Citing this family (23)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3153091B2 (en) * | 1994-03-10 | 2001-04-03 | 株式会社荏原製作所 | Waste treatment method and gasification and melting and combustion equipment |
| US5601788A (en) * | 1991-09-25 | 1997-02-11 | Foster Wheeler Energia Oy | Combined cycle power plant with circulating fluidized bed reactor |
| CA2116745C (en) * | 1993-03-03 | 2007-05-15 | Shuichi Nagato | Pressurized internal circulating fluidized-bed boiler |
| US5445329A (en) * | 1993-11-10 | 1995-08-29 | Anderson; Joseph | Apparatus, system for treating process material such as waste material |
| US5922090A (en) * | 1994-03-10 | 1999-07-13 | Ebara Corporation | Method and apparatus for treating wastes by gasification |
| US5443806A (en) * | 1994-03-22 | 1995-08-22 | A. Ahlstrom Corporation | Treating exhaust gas from a pressurized fluidized bed reaction system |
| EP0722067A3 (en) * | 1995-01-12 | 1998-02-04 | KABUSHIKI KAISHA KOBE SEIKO SHO also known as Kobe Steel Ltd. | Heat recovery apparatus by fluidized bed |
| TW270970B (en) * | 1995-04-26 | 1996-02-21 | Ehara Seisakusho Kk | Fluidized bed combustion device |
| SE9502248L (en) * | 1995-06-21 | 1996-12-22 | Abb Carbon Ab | Method and apparatus for heat energy recovery from flue gases |
| US6139805A (en) * | 1995-11-15 | 2000-10-31 | Ebara Corporation | Fluidized-bed reactor |
| US6282902B1 (en) * | 1997-10-28 | 2001-09-04 | Hitachi, Ltd. | Waste processing system and fuel reformer used in the waste processing system |
| US7285144B2 (en) * | 1997-11-04 | 2007-10-23 | Ebara Corporation | Fluidized-bed gasification and combustion furnace |
| WO1999031202A1 (en) * | 1997-12-18 | 1999-06-24 | Ebara Corporation | Fuel gasifying system |
| US20060198774A1 (en) * | 2005-03-03 | 2006-09-07 | Cross Joseph B | Mercury Removal sorbent |
| US7805923B2 (en) * | 2006-12-12 | 2010-10-05 | Mitsubishi Heavy Industries, Ltd. | Integrated coal gasification combined cycle plant |
| US7814742B2 (en) * | 2006-12-13 | 2010-10-19 | Mitsubishi Heavy Industries, Ltd. | Integrated coal gasification combined cycle plant |
| US7810310B2 (en) * | 2006-12-14 | 2010-10-12 | Mitsubishi Heavy Industries, Ltd. | Integrated coal gasification combined cycle plant |
| CN102083947A (en) * | 2007-06-13 | 2011-06-01 | 沃姆瑟能源解决方案公司 | Mild gasification combined-cycle powerplant |
| US8622029B2 (en) * | 2009-09-30 | 2014-01-07 | Babcock & Wilcox Power Generation Group, Inc. | Circulating fluidized bed (CFB) with in-furnace secondary air nozzles |
| CN102353045B (en) * | 2011-08-05 | 2013-06-26 | 江联重工股份有限公司 | High-efficiency differential-velocity multi-cyclone conical-bed air distribution structure for boiler consuming biomass or garbage fuel |
| US20140065559A1 (en) * | 2012-09-06 | 2014-03-06 | Alstom Technology Ltd. | Pressurized oxy-combustion power boiler and power plant and method of operating the same |
| WO2014160520A1 (en) * | 2013-03-15 | 2014-10-02 | Synthesis Energy Systems, Inc. | Fluidized bed using multiple jets for gas delivery |
| CN110986046B (en) * | 2019-12-11 | 2021-12-21 | 常熟浦发第二热电能源有限公司 | Environment-friendly waste incineration equipment |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| SE8500750L (en) * | 1985-02-18 | 1986-08-19 | Asea Stal Ab | POWER PLANT FOR COMBUSTION OF PARTICULAR FUEL IN FLUIDIZED BED |
| CA1285375C (en) * | 1986-01-21 | 1991-07-02 | Takahiro Ohshita | Thermal reactor |
| US5138982A (en) * | 1986-01-21 | 1992-08-18 | Ebara Corporation | Internal circulating fluidized bed type boiler and method of controlling the same |
| JPH0629652B2 (en) * | 1987-07-13 | 1994-04-20 | 株式会社荏原製作所 | Combustion control device in fluidized bed boiler |
| SE461679B (en) * | 1988-07-06 | 1990-03-12 | Abb Stal Ab | SHOOLERS FOR POWER PLANT |
| US5156099A (en) * | 1988-08-31 | 1992-10-20 | Ebara Corporation | Composite recycling type fluidized bed boiler |
| SE462446B (en) * | 1989-06-29 | 1990-06-25 | Abb Stal Ab | COUNCIL CONTAINER FOR BEDDING MATERIAL AT A POWER PLANT WITH A BRAIN CHAMBER FOR FLUIDIZED BED |
-
1993
- 1993-05-28 US US08/069,686 patent/US5313913A/en not_active Expired - Fee Related
- 1993-06-07 CA CA002097886A patent/CA2097886A1/en not_active Abandoned
Also Published As
| Publication number | Publication date |
|---|---|
| US5313913A (en) | 1994-05-24 |
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| Date | Code | Title | Description |
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| EEER | Examination request | ||
| FZDE | Discontinued |