CA2125655A1 - Self regulating centrifugal separator - Google Patents
Self regulating centrifugal separatorInfo
- Publication number
- CA2125655A1 CA2125655A1 CA002125655A CA2125655A CA2125655A1 CA 2125655 A1 CA2125655 A1 CA 2125655A1 CA 002125655 A CA002125655 A CA 002125655A CA 2125655 A CA2125655 A CA 2125655A CA 2125655 A1 CA2125655 A1 CA 2125655A1
- Authority
- CA
- Canada
- Prior art keywords
- drum
- fluids
- wall
- fluid
- annular
- 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
- 230000001105 regulatory effect Effects 0.000 title claims description 4
- 239000012530 fluid Substances 0.000 claims abstract description 53
- 239000000203 mixture Substances 0.000 claims abstract description 21
- 230000005484 gravity Effects 0.000 claims abstract description 8
- 238000000926 separation method Methods 0.000 claims abstract description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 67
- 230000001419 dependent effect Effects 0.000 claims description 3
- 230000001276 controlling effect Effects 0.000 claims description 2
- 230000000694 effects Effects 0.000 claims description 2
- 238000000034 method Methods 0.000 claims 4
- 238000007599 discharging Methods 0.000 claims 1
- 239000003921 oil Substances 0.000 description 58
- 239000007788 liquid Substances 0.000 description 10
- 241000237074 Centris Species 0.000 description 4
- 239000010779 crude oil Substances 0.000 description 2
- 238000000605 extraction Methods 0.000 description 2
- 239000004576 sand Substances 0.000 description 2
- 101100536354 Drosophila melanogaster tant gene Proteins 0.000 description 1
- 241001527806 Iti Species 0.000 description 1
- 235000018734 Sambucus australis Nutrition 0.000 description 1
- 244000180577 Sambucus australis Species 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 239000011236 particulate material Substances 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B04—CENTRIFUGAL APPARATUS OR MACHINES FOR CARRYING-OUT PHYSICAL OR CHEMICAL PROCESSES
- B04B—CENTRIFUGES
- B04B1/00—Centrifuges with rotary bowls provided with solid jackets for separating predominantly liquid mixtures with or without solid particles
- B04B1/02—Centrifuges with rotary bowls provided with solid jackets for separating predominantly liquid mixtures with or without solid particles without inserted separating walls
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B04—CENTRIFUGAL APPARATUS OR MACHINES FOR CARRYING-OUT PHYSICAL OR CHEMICAL PROCESSES
- B04B—CENTRIFUGES
- B04B11/00—Feeding, charging, or discharging bowls
- B04B11/02—Continuous feeding or discharging; Control arrangements therefor
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S494/00—Imperforate bowl: centrifugal separators
- Y10S494/901—Imperforate bowl: centrifugal separators involving mixture containing oil
Abstract
A centrifugal separator comprises a drum (1) rotatable about its axis within which annular walls (10, 20) define discharge chambers (11, 21) at the ends of the drum, from which separated fluids of different specific gravities are discharged by respective scoops (14, 24). Alternatively, annular walls (44, 45 and 47, 49) define both such chambers at one end only of the drum. The dimensions of the annular walls are chosen so that the separator is self-regulating, in that the separated fluids are discharged independently of the proportions of the fluids in the incoming mixture, so that operation of the separator does not have to be controlled in response to sensing of the separation process within the drum.
Description
P~T/G~92/0231û
2~256ri~) 21 JANUARY 1994 CENTRIFUGAL SEPAR~TOR
- The invention relates to centrifuges, or centri~ugal separators~ su~h as are used separating the component~ of a mixed fluid stream.
Centrifugal separators typically compri~e a ve~sel with a cylindrical wall which is rotated abou~ its axis~ A
mixture of fluids of dif~ere~t specifi~ sravities is introduced and concentriG annular layer~ of the i~diYidual , . . ~
fluids are formed, with the fluid of greatest specifi~
gravity ~orming the outermost layer against the cylindrical wall and with the liquid with the lea~t specif ic gravity orming the layer nearest the axi~. The separation effected in this way within ths centrifuge has of cour e to be maintain~d ~uring extraction of the liquids from it, in spite of varying proportions of the liquid in the :incoming mixture~. Operation of the cent;rifuge can be controlled by a flow control system dependent on the use of sensing devicss to detect the positions: of the level of the layers or radial interface between them, as described,~:~for ~example in US~
Patent 4 846 780. The level or interface sensing means and :
related control arra~ments represent a considerable ~;
complication, making a~ sub~tantial contribution ~to th~:
complexity and cost of the:equipment. ~ : ~
Th~ pr~ent inventi:on i8 accordingly concerned with the ,~
provision of a centrifuge or centrifugal separator which i~
self-regula~ing and thu not dependen~:for its operation o~
the sen~i~g~of the~positio~ within it o:f an interface between adjacent layer~of ~eparated liquids.
The ~invention acaordingly provides a centri~uge ~or regulating the flow~o~ fluids so as to effect separation of first and second~uids of a fir~t ~nd a seaond, greater, specific gravity, respectively, from a mixture of the fluid~
1~3 SUBSTlrUTE SHEEI
P~7~G~ 9 2 / 0 2 3 1 0 212S6~ 21 J~N~ y 1Q~
regardless of the proportions of the fluids in the mixture, the centrifuge comprising a drum (1) rotatable about the axis (6) thereof to form an annular layer (9) of the second fluid around an annular layer (7) of the ~irst fluid, and first (10,11,14,15) and second (20~21,24,25) discharge chambers ~11,12) defined by respective first and second walls (10,20) providing ~irst and seco~d annular weir edge~ controlling the respective discharge f 10WB, fOr respective discharge of the first and second fluid~ from the re~pective layer~ outwardly of the drum, charact~ri~ed in that a sleeve (26) concentric with the drum axi~ (6) ~xtends from the ~econd wall towards the first wall to provide a generally axial flow path for th~
second fluid which reverses direction at the free end of the sleeve, and extends into the second discharge chamber between the second wall and the side wall ~2) of the drum (l).
Discharge from the ~entrifuge is;effected by scoops ope~ating in ~coop chambers ormed at the respective axial end~ of the centrlfuge, and flows of the liquids from the separated layers within the main volume of the ~entrifuge i5 controlled by annular plates or baffles forming weirs which are so dimensioned as to substantially prevent flow~ from a first layer into the scoop chamber recei~ing flow rom the other layer, even when input to the centri~uge consist~ ;
~ubstantially entirely of the liquid fo ~ ing the first layer~
Centrifugal :separator devices in accordance with the :
invention can be employed for example to separat~ oil~from water in an oil extractio~ system. ~ well stream may contain ga~ Oilg watBr and particulate material,~ for exampl~, sand.
After rem~al of sand and ~as, separation of th~ oil and water has to be effected to ~btain a yield of u~eful oil thu~
this can be readily~e~fected by means of the centrifuge of the inventio~, which i8 not however lLmited to thi~ u~e.
The invention i~ further described below, by way of example~ with reference to th~ accompanying drawi~g5, in .
~ A~ a Ir~V~ j Sl;a~ i7 UrE SHEET
65~ JA,~ R~ 94 -2a-which:
Figure 1 is a schematic cross-sectioalal side view of a typical centrifuge, Figure 2 is a partial ~Yiew, on a slightly larger scale, c:orxesponding to the lower left hand part of Figure 1 but showin~ a centrifuge and modified in ac:cordance with the pre~ent invent`ion, and indicating dimensions ref erred to in ` ~
the desc:ription;
Figure 3 resembles Figure 2 but corresponds to the lower right hand ~ide of Figure l; and Figure 4 i8 a æchematic cross-Rectional view o~ a second centrif uge in accordance wit~ the în~ention .
~he centrifuge o~ Figure 1 comprise~ a rotatable ~
housing or drum 1 with: a cylindrical outer wall 2 and~ end , I ' I ' , : ~ ~' '~ ' '' ` "'' `' ' ' ' '` ' '' ` ' ' ~ . ' ` : ' ' ~ ~ ' ` ` ' .:' O 93/l lX77 21 2 ~ PCI/GB92/02310 5. The drum 1 is mounted so as to be rotatably driven about its axis 6 by any appropriate drive me~ns ( ns~t shown ) . In the Figure, the axis 6 is shown as extending horizontally but the axis can be vertical or have any other desired orientation. A mixture of oil a~d water, or of other liguid~
of different specific gravities, is introduced into the drum by a suitable f eeder unit ( not shown ) and 1:he rotatio~ of the drum cause~-the mixture to separate into concentric layers becau3e o~ the dif ferent specifi~ gra~ities of the li~uid~.
Thus, an- inner annular layer 7 of oil be~omes surrounded by an outer a~nular layer of water 9 confined externally by the cylindrical wall 2 of the drum~
It is of course necessary to arrange ~or separate extraction from the oil and the water layers, and at a position ~paced from the rightha~d end wall 5, a transver~e annular inner wall 10 exte~ds inwardly from the wall 2 to def ine with the end wall an oil E~C:OOp or ~ischar~e chamber 11 . ' ~ )il enters the cham}:~er 11 f rom the layer 7 over the inner edge 12 of the annular wall 10 aIld discharges from the drum 1 by way of an oil scoop 14 within the chamber and an axial discharge pipe 15.
Water is similarly dischargecl from the lefthand end of the drum 1, from a water scoop or discharge chamber 21, : by way oiE a water scoop`24 and an axially directed discharge pipe 25. The water discharge chamber is again defined by an annular tran3verse wall,~ wall 20, spaced from the end~wall 4, but the annular wall 2 0, is spaced inwardly f rom the drum wall, and ~-a 'separator ~leeve 2 6, extends axially f rom its outer edge towards ~he oil scoop chamber to a position spaced ~rom the wall 10 . Water consequently f lows axially f irst towards the oil discharge chamber and it then r~verses direction to flow axially into the water scoop chambsr.
For a total fluid flow through the centrifuge of 25, ûûO
, . ..... . . . " , . ... ... . . . . . . .
W~3/llX77 PCT/GB92/02310 2~5~5 -4- ~;
bbl/d (165m /hJ, a maxLmum water flow of 12.500 bbl/d (8~m /h), and a maximum oil fl~w of 18,000 bbl/d (119m /h), suitable operating characteristics and dimensions of the centrifuge can be dete~mined by evaluation of the flow paths, a~ follows:
Density of crude oil: p(o) = 870 kg/m De~sity of water: p( ) - 1000 kg~m C~ntrifuge rotation speed: n - 3600 rpm, = 377 rad/~ea Diameter of the ~ree surface of Inside diameter of the cylindrical wall 2: 457 mm water in th~ water scoop cha~ber 11: 384.5 mm Outer diameter of the ~eparator sleeve 26: 43g mm Inner di~meter of the separator sleeve 26: 433 mm Diameter of water/oil interface: 407 mm Diam~ter of th free surface of the oil laysr 7: 381 ~m Diameter of ed~ of wall 20 at entry into the water ~coop ~hamber 21: 443 mm ~' Th~ centrifuge of Figure 1 can thus ~e desiyned to operate : -satisfactorily~ tha~ is, without discharge ~f any substantial amount of water through:pipe 15, or of oil through pipe 25, -;
pro~ided the ratio of oil to water in the in~oming mixture ~.
does not vary very substantially. To enable the:centifuge to operate with inco~nq mixtures which vary considerably in the ratio of the ~omponents, the centrifuge :is modified and dLmensione~-, 8 app~ars from Figures 2 and 3.
A~ $hown in Figure 2 an additional weir or:annular wall ~;:
30 ext~nds inwardly from the cyli~drical wall 2 between the ~:
water saoop 24 and the wall 20, so ~hat its inner edge 31 controls liquid entry into the water scoop ~hamber~
~ rom the dimensions given above the liquid level~ Dsw in ,~ 9~/11877 21 2 ~ 5 5 S pcr/GB92/o231o Figure 2, ( 384 ~ 5 mm) in the water scoop chamber is l . 75 mm below the level of the oil layer in the main s~olumn of th~
drum, Dso in Figure 3, (3131 mm~. If the wall 30 has an internal diameter of 389 . 5 mm, water at the maximum water flow of 12 . 500 bbltd, will pass over the wail into 1:he water scoop chamber 2 l .
Such an arrangement will be s~3lf-regulating provided that the water scoop 24 is able to take out the wat~r that ~-comes irlto the water discharge chamber with a f Iow charac:t~ristic providing capacity which increa~es proportionally to the depth of submergence of the scoop and shows no m lfu~ction at different flow rat~ due for example to ga~ entering t~e scoop.
The oil di~charge arrangement will be s~lf-regulating .with the distance dE shown in Figure 3 equal to 3O25 mm.
Wi~h the maxLmum oil inflow (18.00 bbl/d), oil will ~low ov~x the ~dge 12 and into the oil scoop chamber 11.
Suppose first that the centxifuge is operated normally with a crude oil mixture of oi:l and water which suddenly changes so a~ to contain sub~tantially no water and to con~ist substantially only of oil.
The flow of water over the edge 31 of the wall 30 into the water discharge chamber will be reduced until the water level Dsw in the chamber drops to the edge diameter of the wall 30 (389.5 mm). Provided the oil flow is maintained at 18,0~0 bbl/d the oil level inside the centrifug~ will remain con~tant as this is determined by the diameter of the edge of the wall 1OD
As w~ér drains from the centrifuge the wate~/oil interface increases in diameter. The lo~ation of the interfa~e can be found from:
p(w)*(Dbw -Dsw j = p(o)*~Dwo -Ds ) + p(w)*(Dbw -Dwo ) :
W~ 77 PCT/GB92/02310 ~ ,rj In this equation, and as show~in Figure 2:
Dsw is the diameter of the free surface of water in the water scoop chamber 11, Dbw is the inside diameter of the cylindrical wall 2 Dwo is the diameter of the water/oil interface, and Ds is the free surface diameter of the oil layer 7 With the dimensions given above the result is:
D~o = 442 mm The surface of the oil (Ds) is at ~81 mm, so that the thicknes~ o the oil layer 7 increases from 13 mm to 30.5 mm and the oil layer enters the retur~ layer of the water.
Accordingly to pr~vent this, the thi¢kne3s of the wall of the liquid separator ~leeve 2 6 is increased, or the relative thiakne~se of the oil and water layer~ i~ altered by appropriate selection of Dsw and Dso. -:Suppose now: that the centrifuge, after operatingnormally with a mixture of oil and water, suddenly experiences an inflow: consis~ing essentially of water and containing substantially no oil . The f low of oil ov~x the edge 12 of the wall 1~ into the oil discharge chamber ll is reduced to zero and the diameter of the water~oil interf ace will de~rease until a balance is reached with~ the surface of the water in the wat~r discharge chamber inlet and the edge 12.
ProYid~3d the wat~r flow is maintained at: 12 ,500 bl~d, the water l~,~el inside the water scoop ch~er 21 will remain constant at 384 ,. 5 mm. The edge 12 into the oil scoop ch~er 11 : : ~ . ~
being at 387.5 mm~ is below the water surface ~iameter. This re~ults f irstly in a :drainage o~ oil f rom the s~parator, af ter which water would f low over the edge 12 into the oil ,:
:~.
: .
~/t1~77 2 1 2 S 6 5 5 PC~/GB92/02310 scoop ch~mber.
In accordance with the invention the thickness of the layers is altered ~o create a larger height differ~nce between the water surface level in the water scoop ch~mbsr and the oil surface level inside the main volume of the centrifuge.
By arranging for the thickness of the oil a~d water layers to increase from 13 to 25 mm, the diameter of the c~ntrifuge being held constant, the following d~ensions are obtained:
Surface diameter (Dso) of the oil layer 7 339 mm Dîameter ~Dwo~ of the waterJoil interface 407 mm Outer di~meter of separator sleeve 26: Dyso - 439 mm Interior diameter ~Db~) of the drum 2: 457 Diameter ~Dsw) of the surface of the water entering the ~c:oop chamber 2l 349 mm ~ .
The required thickne~s of the water flowing over the edge 31 into the water scoop chamber is still 2.5 mm, giving an edge ~iameter of 354 mm.
The thickness of~ the oil-f~lowing into the~ oil scoop chamber ll has ~o be adjusted from 3.25 mm to 3.5 mm, because the diameter of the surface is reduced and the pressure caused by centri~ugal force is lower.
The diameter of the~;edge 12 at the oil ch ~ er ll is now 346 mm. With an input of l00~ water, the level inside the centrifuga will be lower~than the oil edge diameter and there is`no longer any risk that water will enter the oil SCQOp:
chamber ll. With an input of 100% oil, the water/oil interface diameter (Dwo)~ will increase to 441~5~mm, allowing a slight oil ~ntry into the water scoop chamber 2l so the diameter of the edge 31 is increased about 1 mm andior the thi~kness of the separator sleeve 26 is i~creased, to prev@nt ,:
,....
.~:
WO93/11~77 PCT/GB92/02310 ~2~ 8-oil from entering the water ~coop chamber.
The apparatus illustrated in Figures 1-3 provides for the oil and water discharge pipes 15,25 to be located at Qpposed ends of the drum 1, but a centrifuge in accordance with the invention can be organised so that both the di~charge pipes are a~ the same end, as shown in Figure 4, in whi~h the reference numerals employed for certain parts of the centrifuge of Figures 1-3 are used to indicate part~ with lar function~. -The mixture to be separated is introdu~ed into the drumat an inlet end 39 defined by an axially outwardly convergent fru~to conical end wall 40 against which forms the water layer 9 in a thickness which increases in the flow directLon towards the cylindrical wall 2 a~d the outlet end 42 of the centrifuge. The outer layer 9 of oil i~ similarly formed, -:
with a~ intermediate layer 41 of the un~eparated mixture between it and the layer 7. The thicknes~ cf the intermediate layer 41 decreases to zero at the outlet e~d of the centrifuge~ as its componen~s -4eparate out into the oil and water layers~
Adjacent the outlet end 42, the oil scoop cha~ber 11 is defined by two axially spaced annular walls 44, 45 joined at their outer periphery by a short cylindrical portion 46 r spaced from the wall 2. The oil in the layer 7 enters the ~hamber 11 over the outer edge of the wall 44 and is removed by the oil scoop 14. The water scoop chamber 21 is defined by two further axially spaced annular~end wall~ 47, 49 whi~h extend directly from the cylindrical wall 2. The wall 49 adjacent the'outlet end ~2 has the same inner diameter as the wall 45 but the diameter of the wall 47 ex~eeds that of wall 44.
Water from the layer 9 thus enters the water scoop chamber 21 between the~wall 2 and the sleeve :46, moving them radially inwardly and over the i~ner edge of the wall 47, to 21 2~ 6S5 be extracted by the water sc~op 14 Th~ centrifuge of Figure 4 thus operates with uni-directional flow of the mixture and of the oil and water layers, without the reversal of axial direction required for the water flow in the centrifuge of Figures 1-30 The centrifuge of Figure 4 is of course dimensioned ~o a~ to be self-regulating in the same way as the centrifuge of Figure 1-3, and the dimensi~ns noted in Figures 2 and 3 are indicated in Figure 4.
The internal diameter of the annular wall may be predetermined a~ a function of the Reynolds number for th~
fluid mixture.
Although the invention has been specifically described with reference to eentrifuge~ for separating oil and water, it i~ to be understood that the invention could be embodied in centrifuges designed to separate other liquid~. The invention ran be embodied in a variety of ways other thAn as specifically described and illu~trated.
. .. , ,, ::
- The invention relates to centrifuges, or centri~ugal separators~ su~h as are used separating the component~ of a mixed fluid stream.
Centrifugal separators typically compri~e a ve~sel with a cylindrical wall which is rotated abou~ its axis~ A
mixture of fluids of dif~ere~t specifi~ sravities is introduced and concentriG annular layer~ of the i~diYidual , . . ~
fluids are formed, with the fluid of greatest specifi~
gravity ~orming the outermost layer against the cylindrical wall and with the liquid with the lea~t specif ic gravity orming the layer nearest the axi~. The separation effected in this way within ths centrifuge has of cour e to be maintain~d ~uring extraction of the liquids from it, in spite of varying proportions of the liquid in the :incoming mixture~. Operation of the cent;rifuge can be controlled by a flow control system dependent on the use of sensing devicss to detect the positions: of the level of the layers or radial interface between them, as described,~:~for ~example in US~
Patent 4 846 780. The level or interface sensing means and :
related control arra~ments represent a considerable ~;
complication, making a~ sub~tantial contribution ~to th~:
complexity and cost of the:equipment. ~ : ~
Th~ pr~ent inventi:on i8 accordingly concerned with the ,~
provision of a centrifuge or centrifugal separator which i~
self-regula~ing and thu not dependen~:for its operation o~
the sen~i~g~of the~positio~ within it o:f an interface between adjacent layer~of ~eparated liquids.
The ~invention acaordingly provides a centri~uge ~or regulating the flow~o~ fluids so as to effect separation of first and second~uids of a fir~t ~nd a seaond, greater, specific gravity, respectively, from a mixture of the fluid~
1~3 SUBSTlrUTE SHEEI
P~7~G~ 9 2 / 0 2 3 1 0 212S6~ 21 J~N~ y 1Q~
regardless of the proportions of the fluids in the mixture, the centrifuge comprising a drum (1) rotatable about the axis (6) thereof to form an annular layer (9) of the second fluid around an annular layer (7) of the ~irst fluid, and first (10,11,14,15) and second (20~21,24,25) discharge chambers ~11,12) defined by respective first and second walls (10,20) providing ~irst and seco~d annular weir edge~ controlling the respective discharge f 10WB, fOr respective discharge of the first and second fluid~ from the re~pective layer~ outwardly of the drum, charact~ri~ed in that a sleeve (26) concentric with the drum axi~ (6) ~xtends from the ~econd wall towards the first wall to provide a generally axial flow path for th~
second fluid which reverses direction at the free end of the sleeve, and extends into the second discharge chamber between the second wall and the side wall ~2) of the drum (l).
Discharge from the ~entrifuge is;effected by scoops ope~ating in ~coop chambers ormed at the respective axial end~ of the centrlfuge, and flows of the liquids from the separated layers within the main volume of the ~entrifuge i5 controlled by annular plates or baffles forming weirs which are so dimensioned as to substantially prevent flow~ from a first layer into the scoop chamber recei~ing flow rom the other layer, even when input to the centri~uge consist~ ;
~ubstantially entirely of the liquid fo ~ ing the first layer~
Centrifugal :separator devices in accordance with the :
invention can be employed for example to separat~ oil~from water in an oil extractio~ system. ~ well stream may contain ga~ Oilg watBr and particulate material,~ for exampl~, sand.
After rem~al of sand and ~as, separation of th~ oil and water has to be effected to ~btain a yield of u~eful oil thu~
this can be readily~e~fected by means of the centrifuge of the inventio~, which i8 not however lLmited to thi~ u~e.
The invention i~ further described below, by way of example~ with reference to th~ accompanying drawi~g5, in .
~ A~ a Ir~V~ j Sl;a~ i7 UrE SHEET
65~ JA,~ R~ 94 -2a-which:
Figure 1 is a schematic cross-sectioalal side view of a typical centrifuge, Figure 2 is a partial ~Yiew, on a slightly larger scale, c:orxesponding to the lower left hand part of Figure 1 but showin~ a centrifuge and modified in ac:cordance with the pre~ent invent`ion, and indicating dimensions ref erred to in ` ~
the desc:ription;
Figure 3 resembles Figure 2 but corresponds to the lower right hand ~ide of Figure l; and Figure 4 i8 a æchematic cross-Rectional view o~ a second centrif uge in accordance wit~ the în~ention .
~he centrifuge o~ Figure 1 comprise~ a rotatable ~
housing or drum 1 with: a cylindrical outer wall 2 and~ end , I ' I ' , : ~ ~' '~ ' '' ` "'' `' ' ' ' '` ' '' ` ' ' ~ . ' ` : ' ' ~ ~ ' ` ` ' .:' O 93/l lX77 21 2 ~ PCI/GB92/02310 5. The drum 1 is mounted so as to be rotatably driven about its axis 6 by any appropriate drive me~ns ( ns~t shown ) . In the Figure, the axis 6 is shown as extending horizontally but the axis can be vertical or have any other desired orientation. A mixture of oil a~d water, or of other liguid~
of different specific gravities, is introduced into the drum by a suitable f eeder unit ( not shown ) and 1:he rotatio~ of the drum cause~-the mixture to separate into concentric layers becau3e o~ the dif ferent specifi~ gra~ities of the li~uid~.
Thus, an- inner annular layer 7 of oil be~omes surrounded by an outer a~nular layer of water 9 confined externally by the cylindrical wall 2 of the drum~
It is of course necessary to arrange ~or separate extraction from the oil and the water layers, and at a position ~paced from the rightha~d end wall 5, a transver~e annular inner wall 10 exte~ds inwardly from the wall 2 to def ine with the end wall an oil E~C:OOp or ~ischar~e chamber 11 . ' ~ )il enters the cham}:~er 11 f rom the layer 7 over the inner edge 12 of the annular wall 10 aIld discharges from the drum 1 by way of an oil scoop 14 within the chamber and an axial discharge pipe 15.
Water is similarly dischargecl from the lefthand end of the drum 1, from a water scoop or discharge chamber 21, : by way oiE a water scoop`24 and an axially directed discharge pipe 25. The water discharge chamber is again defined by an annular tran3verse wall,~ wall 20, spaced from the end~wall 4, but the annular wall 2 0, is spaced inwardly f rom the drum wall, and ~-a 'separator ~leeve 2 6, extends axially f rom its outer edge towards ~he oil scoop chamber to a position spaced ~rom the wall 10 . Water consequently f lows axially f irst towards the oil discharge chamber and it then r~verses direction to flow axially into the water scoop chambsr.
For a total fluid flow through the centrifuge of 25, ûûO
, . ..... . . . " , . ... ... . . . . . . .
W~3/llX77 PCT/GB92/02310 2~5~5 -4- ~;
bbl/d (165m /hJ, a maxLmum water flow of 12.500 bbl/d (8~m /h), and a maximum oil fl~w of 18,000 bbl/d (119m /h), suitable operating characteristics and dimensions of the centrifuge can be dete~mined by evaluation of the flow paths, a~ follows:
Density of crude oil: p(o) = 870 kg/m De~sity of water: p( ) - 1000 kg~m C~ntrifuge rotation speed: n - 3600 rpm, = 377 rad/~ea Diameter of the ~ree surface of Inside diameter of the cylindrical wall 2: 457 mm water in th~ water scoop cha~ber 11: 384.5 mm Outer diameter of the ~eparator sleeve 26: 43g mm Inner di~meter of the separator sleeve 26: 433 mm Diameter of water/oil interface: 407 mm Diam~ter of th free surface of the oil laysr 7: 381 ~m Diameter of ed~ of wall 20 at entry into the water ~coop ~hamber 21: 443 mm ~' Th~ centrifuge of Figure 1 can thus ~e desiyned to operate : -satisfactorily~ tha~ is, without discharge ~f any substantial amount of water through:pipe 15, or of oil through pipe 25, -;
pro~ided the ratio of oil to water in the in~oming mixture ~.
does not vary very substantially. To enable the:centifuge to operate with inco~nq mixtures which vary considerably in the ratio of the ~omponents, the centrifuge :is modified and dLmensione~-, 8 app~ars from Figures 2 and 3.
A~ $hown in Figure 2 an additional weir or:annular wall ~;:
30 ext~nds inwardly from the cyli~drical wall 2 between the ~:
water saoop 24 and the wall 20, so ~hat its inner edge 31 controls liquid entry into the water scoop ~hamber~
~ rom the dimensions given above the liquid level~ Dsw in ,~ 9~/11877 21 2 ~ 5 5 S pcr/GB92/o231o Figure 2, ( 384 ~ 5 mm) in the water scoop chamber is l . 75 mm below the level of the oil layer in the main s~olumn of th~
drum, Dso in Figure 3, (3131 mm~. If the wall 30 has an internal diameter of 389 . 5 mm, water at the maximum water flow of 12 . 500 bbltd, will pass over the wail into 1:he water scoop chamber 2 l .
Such an arrangement will be s~3lf-regulating provided that the water scoop 24 is able to take out the wat~r that ~-comes irlto the water discharge chamber with a f Iow charac:t~ristic providing capacity which increa~es proportionally to the depth of submergence of the scoop and shows no m lfu~ction at different flow rat~ due for example to ga~ entering t~e scoop.
The oil di~charge arrangement will be s~lf-regulating .with the distance dE shown in Figure 3 equal to 3O25 mm.
Wi~h the maxLmum oil inflow (18.00 bbl/d), oil will ~low ov~x the ~dge 12 and into the oil scoop chamber 11.
Suppose first that the centxifuge is operated normally with a crude oil mixture of oi:l and water which suddenly changes so a~ to contain sub~tantially no water and to con~ist substantially only of oil.
The flow of water over the edge 31 of the wall 30 into the water discharge chamber will be reduced until the water level Dsw in the chamber drops to the edge diameter of the wall 30 (389.5 mm). Provided the oil flow is maintained at 18,0~0 bbl/d the oil level inside the centrifug~ will remain con~tant as this is determined by the diameter of the edge of the wall 1OD
As w~ér drains from the centrifuge the wate~/oil interface increases in diameter. The lo~ation of the interfa~e can be found from:
p(w)*(Dbw -Dsw j = p(o)*~Dwo -Ds ) + p(w)*(Dbw -Dwo ) :
W~ 77 PCT/GB92/02310 ~ ,rj In this equation, and as show~in Figure 2:
Dsw is the diameter of the free surface of water in the water scoop chamber 11, Dbw is the inside diameter of the cylindrical wall 2 Dwo is the diameter of the water/oil interface, and Ds is the free surface diameter of the oil layer 7 With the dimensions given above the result is:
D~o = 442 mm The surface of the oil (Ds) is at ~81 mm, so that the thicknes~ o the oil layer 7 increases from 13 mm to 30.5 mm and the oil layer enters the retur~ layer of the water.
Accordingly to pr~vent this, the thi¢kne3s of the wall of the liquid separator ~leeve 2 6 is increased, or the relative thiakne~se of the oil and water layer~ i~ altered by appropriate selection of Dsw and Dso. -:Suppose now: that the centrifuge, after operatingnormally with a mixture of oil and water, suddenly experiences an inflow: consis~ing essentially of water and containing substantially no oil . The f low of oil ov~x the edge 12 of the wall 1~ into the oil discharge chamber ll is reduced to zero and the diameter of the water~oil interf ace will de~rease until a balance is reached with~ the surface of the water in the wat~r discharge chamber inlet and the edge 12.
ProYid~3d the wat~r flow is maintained at: 12 ,500 bl~d, the water l~,~el inside the water scoop ch~er 21 will remain constant at 384 ,. 5 mm. The edge 12 into the oil scoop ch~er 11 : : ~ . ~
being at 387.5 mm~ is below the water surface ~iameter. This re~ults f irstly in a :drainage o~ oil f rom the s~parator, af ter which water would f low over the edge 12 into the oil ,:
:~.
: .
~/t1~77 2 1 2 S 6 5 5 PC~/GB92/02310 scoop ch~mber.
In accordance with the invention the thickness of the layers is altered ~o create a larger height differ~nce between the water surface level in the water scoop ch~mbsr and the oil surface level inside the main volume of the centrifuge.
By arranging for the thickness of the oil a~d water layers to increase from 13 to 25 mm, the diameter of the c~ntrifuge being held constant, the following d~ensions are obtained:
Surface diameter (Dso) of the oil layer 7 339 mm Dîameter ~Dwo~ of the waterJoil interface 407 mm Outer di~meter of separator sleeve 26: Dyso - 439 mm Interior diameter ~Db~) of the drum 2: 457 Diameter ~Dsw) of the surface of the water entering the ~c:oop chamber 2l 349 mm ~ .
The required thickne~s of the water flowing over the edge 31 into the water scoop chamber is still 2.5 mm, giving an edge ~iameter of 354 mm.
The thickness of~ the oil-f~lowing into the~ oil scoop chamber ll has ~o be adjusted from 3.25 mm to 3.5 mm, because the diameter of the surface is reduced and the pressure caused by centri~ugal force is lower.
The diameter of the~;edge 12 at the oil ch ~ er ll is now 346 mm. With an input of l00~ water, the level inside the centrifuga will be lower~than the oil edge diameter and there is`no longer any risk that water will enter the oil SCQOp:
chamber ll. With an input of 100% oil, the water/oil interface diameter (Dwo)~ will increase to 441~5~mm, allowing a slight oil ~ntry into the water scoop chamber 2l so the diameter of the edge 31 is increased about 1 mm andior the thi~kness of the separator sleeve 26 is i~creased, to prev@nt ,:
,....
.~:
WO93/11~77 PCT/GB92/02310 ~2~ 8-oil from entering the water ~coop chamber.
The apparatus illustrated in Figures 1-3 provides for the oil and water discharge pipes 15,25 to be located at Qpposed ends of the drum 1, but a centrifuge in accordance with the invention can be organised so that both the di~charge pipes are a~ the same end, as shown in Figure 4, in whi~h the reference numerals employed for certain parts of the centrifuge of Figures 1-3 are used to indicate part~ with lar function~. -The mixture to be separated is introdu~ed into the drumat an inlet end 39 defined by an axially outwardly convergent fru~to conical end wall 40 against which forms the water layer 9 in a thickness which increases in the flow directLon towards the cylindrical wall 2 a~d the outlet end 42 of the centrifuge. The outer layer 9 of oil i~ similarly formed, -:
with a~ intermediate layer 41 of the un~eparated mixture between it and the layer 7. The thicknes~ cf the intermediate layer 41 decreases to zero at the outlet e~d of the centrifuge~ as its componen~s -4eparate out into the oil and water layers~
Adjacent the outlet end 42, the oil scoop cha~ber 11 is defined by two axially spaced annular walls 44, 45 joined at their outer periphery by a short cylindrical portion 46 r spaced from the wall 2. The oil in the layer 7 enters the ~hamber 11 over the outer edge of the wall 44 and is removed by the oil scoop 14. The water scoop chamber 21 is defined by two further axially spaced annular~end wall~ 47, 49 whi~h extend directly from the cylindrical wall 2. The wall 49 adjacent the'outlet end ~2 has the same inner diameter as the wall 45 but the diameter of the wall 47 ex~eeds that of wall 44.
Water from the layer 9 thus enters the water scoop chamber 21 between the~wall 2 and the sleeve :46, moving them radially inwardly and over the i~ner edge of the wall 47, to 21 2~ 6S5 be extracted by the water sc~op 14 Th~ centrifuge of Figure 4 thus operates with uni-directional flow of the mixture and of the oil and water layers, without the reversal of axial direction required for the water flow in the centrifuge of Figures 1-30 The centrifuge of Figure 4 is of course dimensioned ~o a~ to be self-regulating in the same way as the centrifuge of Figure 1-3, and the dimensi~ns noted in Figures 2 and 3 are indicated in Figure 4.
The internal diameter of the annular wall may be predetermined a~ a function of the Reynolds number for th~
fluid mixture.
Although the invention has been specifically described with reference to eentrifuge~ for separating oil and water, it i~ to be understood that the invention could be embodied in centrifuges designed to separate other liquid~. The invention ran be embodied in a variety of ways other thAn as specifically described and illu~trated.
. .. , ,, ::
Claims (20)
1. A centrifuge for regulating the flow of fluids so as to effect separation of first and second fluids of a first and a second, greater, specific gravity, respectively, from a mixture of the fluids regardless of the proportions of the fluids in the mixture, the centrifuge comprising a drum (1) rotatable about the axis (6) thereof to form an annular layer (9) of the second fluid around an annular layer (7) of the first fluid, and first (10,11,14,15) and second (20,21,24,25) discharge chambers (11,12) defined by respective first and second walls (10,20) providing first and second annular weir edges controlling the respective discharge flows, for respective discharge of the first and second fluids from the respective layers outwardly of the drum, characterised in that a sleeve (26) concentric with the drum axis (6) extends from the second wall towards the first wall to provide a generally axial flow path for the second fluid which reverses direction at the free end of thee sleeve, and extends into the second discharge chamber between the second wall and the side wall (2) of the drum (1).
2. A centrifuge as claimed in claim 1 having an annular wall (30) extending inwardly from the drum side wall (2) within the second discharge chamber to a position radially short of the second weir edge.
3. A centrifuge as claimed in claim 1 wherein the first and second discharge chambers (11,21) are defined at one end of the drum (1) respectively by an annular channel inwardly spaced from the drum side wall (2) and having a first wall (44) defining the first weir edge and a second annular wall extending radially inwardly of the weir edge, and by an annular channel comprising walls extending from the drum side wall of which the outer wall (21) defines the second weir edge.
4. A centrifuge as claimed in preceding claim wherein the discharge means comprise respective scoops (14,24) for extracting fluids from the first and second discharge chambers (11,21) and discharging the fluids axially of the drum.
5. A centrifugal separator comprising:
a drum (1) for receiving a fluid mixture to be separated;
means for rotating the drum (1) about an axis thereof;
baffle means separating two discharge chambers for receiving respective separated fluids from the drum; and means for drawing off the separated fluids from the respective discharge chambers;
wherein the baffle means comprises an annular wall (10) extending radially into the drum and having an internal diameter predetermined as a function of at least one of the relative specific gravities of the separated fluids, the velocities of the separated fluids and the depth of fluid in the drum, so that the separator is self-regulating.
a drum (1) for receiving a fluid mixture to be separated;
means for rotating the drum (1) about an axis thereof;
baffle means separating two discharge chambers for receiving respective separated fluids from the drum; and means for drawing off the separated fluids from the respective discharge chambers;
wherein the baffle means comprises an annular wall (10) extending radially into the drum and having an internal diameter predetermined as a function of at least one of the relative specific gravities of the separated fluids, the velocities of the separated fluids and the depth of fluid in the drum, so that the separator is self-regulating.
6. A centrifugal separator as claimed in claim 5 wherein the internal diameter of the annular wall is predetermined as a function of the Reynolds number for the fluid mixture.
7. A centrifugal separator a claimed in claim 5 or 6 wherein the baffle means comprise a second annular wall extending radially into the drum to define the second discharge chamber for separated fluid.
8. A centrifugal separator as claimed in claim 7 wherein the two discharge chambers are at opposed ends of the drum.
9. A centrifugal separator as claimed in claim 7 wherein the two discharge chambers are at the same end of the drum.
10. A centrifugal separator as claimed in any one of claims 5-9 comprising a separator cylinder arranged with and spaced from and generally parallel with the drum wherein the base of the separator cylinder provides an annular wall at a boundary of one of the annular chambers and the space between the cylinder wall and the drum provides a flow path for one of the separated fluids.
11. A centrifugal separator as claimed in any one of claims 5-9 wherein the internal diameter of the second annular wall is predetermined as a function of at least one of the relative specific gravities of the separated fluids, the velocities of the fluids and the depth of fluid in the separation chamber.
12. A centrifugal separator as claimed in any one of claims 5-9 wherein the means for drawing off fluids comprises a fluid scoop extending into each discharge chamber and connected to axially extending discharge pipes and wherein the position and dimensions of the scoops are predetermined in accordance with the operating parameter of the separator.
13. A centrifugal separator as claimed in any one of claims 5-9 wherein the internal dimensions of the separator are predetermined as a function of the flow paths of the fluids.
14. A centrifugal separator as claimed in any one of claims 5-9 wherein the means for drawing off fluids is adapted to draw off fluid at a rate proportional to the depth of submersion of the scoop in the respective separated fluid.
15. A centrifugal separator as claimed in any one of claims 5-14 wherein the drawing off means is arranged and constructed so as to be independent of different fluid flow rate.
16. A centrifugal separator as claimed in any of claims 5-15 wherein the respective annular walls have dimensions which are chosen to be respectively below the level of the respective fluid by a predetermined distance.
17. A centrifugal separator as claimed in any preceding claim wherein the internal dimensions are chosen so that the separator is self regulating.
18. A process of separating a mixture of fluids by centrifugal action comprising supplying the fluid mixture to an axially rotating drum having at least one annular wall extending radially into the drum to delimit discharge chambers for respective separated fluids and drawing off separated fluid from each drum at a flow rate dependent upon the internal diameter of the annular wall so that the process is self-regulating.
19. A process as claimed in claim 18 having means for drawing off the separated fluids at a flow rate dependent upon the density of the respective fluids.
20. A process as claimed in claim 18 or 19 wherein the fluids comprise oil and water.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB919126415A GB9126415D0 (en) | 1991-12-12 | 1991-12-12 | Centrifugal separator |
| GB9126415.0 | 1991-12-12 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2125655A1 true CA2125655A1 (en) | 1993-06-24 |
Family
ID=10706152
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002125655A Abandoned CA2125655A1 (en) | 1991-12-12 | 1992-12-11 | Self regulating centrifugal separator |
Country Status (12)
| Country | Link |
|---|---|
| US (1) | US5624371A (en) |
| EP (1) | EP0615468B1 (en) |
| JP (1) | JPH07501744A (en) |
| AT (1) | ATE184216T1 (en) |
| BR (1) | BR9206912A (en) |
| CA (1) | CA2125655A1 (en) |
| DE (1) | DE69229956T2 (en) |
| DK (1) | DK0615468T3 (en) |
| ES (1) | ES2137952T3 (en) |
| GB (1) | GB9126415D0 (en) |
| NO (2) | NO305541B1 (en) |
| WO (1) | WO1993011877A1 (en) |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5664420A (en) | 1992-05-05 | 1997-09-09 | Biphase Energy Company | Multistage two-phase turbine |
| DE4330458A1 (en) * | 1992-07-13 | 1995-03-09 | Grumman Aerospace Corp | Device for removing liquid from an air/liquid separator |
| US6238329B1 (en) * | 1999-02-05 | 2001-05-29 | Ernest E. Rogers | Centrifugal separator for mixed immiscible fluids |
| US6440054B1 (en) * | 2000-09-18 | 2002-08-27 | George M. Galik | Apparatus for liquid-liquid extraction |
| FR2841485B1 (en) * | 2002-07-01 | 2004-08-06 | Commissariat Energie Atomique | ANNULAR CENTRIFUGAL EXTRACTOR WITH NOYE AGITATION ROTOR |
| US8636634B2 (en) * | 2007-04-02 | 2014-01-28 | Rasp Technologies, Llc | Reaction and separation processor and process for producing biodiesel |
| JP2011255257A (en) * | 2010-06-05 | 2011-12-22 | Ameroido Nippon Service Sha:Kk | Centrifuge |
| EP2664383A1 (en) * | 2012-05-15 | 2013-11-20 | Miltenyi Biotec GmbH | Centrifugation chamber with deflector shields |
Family Cites Families (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE40702C (en) * | J. EVANS in Philadelphia, Staat Pensylvania, und D. H. BURRELL in Little Falls, Staat New-York, V. St. A | Centrifugal machine for separating three or more parts from a mixed liquid | ||
| GB260071A (en) * | 1925-08-15 | 1926-10-28 | Edward William Green | Improvements in and relating to centrifugal separators |
| US2619280A (en) * | 1948-10-25 | 1952-11-25 | Shell Dev | Centrifugal contactor and method of contacting |
| US3814307A (en) * | 1973-01-12 | 1974-06-04 | Standard Oil Co | Centrifugal clarifier |
| DE2336564A1 (en) * | 1973-07-18 | 1975-04-03 | Inst Neorganicheskoi Chimii Ak | Centrifugal extractor with combined rotor and centrifugal chamber - arranged coaxially with hollow shaft distributor vanes and collectors |
| US4010891A (en) * | 1976-01-08 | 1977-03-08 | Burmah Oil & Gas Company | Vapor removal apparatus for oil/water separator |
| DK87580A (en) * | 1979-03-15 | 1980-09-16 | R E High | SPIN |
| JPS631466A (en) * | 1986-06-19 | 1988-01-06 | Power Reactor & Nuclear Fuel Dev Corp | Centrifugal velocity extractor |
| US4842738A (en) * | 1988-04-29 | 1989-06-27 | Greenspan Harvey P | Centrifuge device |
-
1991
- 1991-12-11 US US08/244,749 patent/US5624371A/en not_active Expired - Lifetime
- 1991-12-12 GB GB919126415A patent/GB9126415D0/en active Pending
-
1992
- 1992-12-11 DE DE69229956T patent/DE69229956T2/en not_active Expired - Fee Related
- 1992-12-11 JP JP5510729A patent/JPH07501744A/en active Pending
- 1992-12-11 CA CA002125655A patent/CA2125655A1/en not_active Abandoned
- 1992-12-11 DK DK92924830T patent/DK0615468T3/en active
- 1992-12-11 WO PCT/GB1992/002310 patent/WO1993011877A1/en active IP Right Grant
- 1992-12-11 EP EP92924830A patent/EP0615468B1/en not_active Expired - Lifetime
- 1992-12-11 BR BR9206912A patent/BR9206912A/en not_active IP Right Cessation
- 1992-12-11 ES ES92924830T patent/ES2137952T3/en not_active Expired - Lifetime
- 1992-12-11 AT AT92924830T patent/ATE184216T1/en not_active IP Right Cessation
-
1994
- 1994-06-10 NO NO942160A patent/NO305541B1/en not_active IP Right Cessation
-
1998
- 1998-12-28 NO NO19986136A patent/NO314838B1/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| EP0615468A1 (en) | 1994-09-21 |
| BR9206912A (en) | 1995-11-21 |
| EP0615468B1 (en) | 1999-09-08 |
| NO986136L (en) | 1994-07-27 |
| NO942160L (en) | 1994-07-27 |
| DK0615468T3 (en) | 2000-04-03 |
| NO986136D0 (en) | 1998-12-28 |
| US5624371A (en) | 1997-04-29 |
| ES2137952T3 (en) | 2000-01-01 |
| DE69229956T2 (en) | 2000-05-04 |
| NO314838B1 (en) | 2003-06-02 |
| ATE184216T1 (en) | 1999-09-15 |
| JPH07501744A (en) | 1995-02-23 |
| DE69229956D1 (en) | 1999-10-14 |
| GB9126415D0 (en) | 1992-02-12 |
| NO942160D0 (en) | 1994-06-10 |
| NO305541B1 (en) | 1999-06-21 |
| WO1993011877A1 (en) | 1993-06-24 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Discontinued |