CN100587030C

CN100587030C - Process for steam cracking of heavy hydrocarbon raw material

Info

Publication number: CN100587030C
Application number: CN03815733A
Authority: CN
Inventors: R·C·斯特尔; A·R·蒂尼克兰托尼奥; J·M·弗莱; D·B·司派瑟; J·N·麦克柯伊; R·D·斯特拉克
Original assignee: Exxon Chemical Patents Inc
Current assignee: ExxonMobil Chemical Patents Inc
Priority date: 2002-07-03
Filing date: 2003-06-27
Publication date: 2010-02-03
Anticipated expiration: 2023-06-27
Also published as: CA2490403A1; KR20050016708A; CN100494318C; JP4403071B2; CA2489876C; AU2003281371A1; CN1665910A; EP1527151A1; ATE396244T1; CN1281715C; EP1523534B1; KR100945121B1; WO2004005433A1; JP2005531683A; CN1665909A; KR20050016709A; CA2489876A1; JP4387301B2; AU2003247755A1; JP5166674B2

Abstract

A process to increase the non-volatile removal efficiency in a flash drum in the steam cracking system. The gas flow from the convection section is converted from mist flow to annular flow before entering the flash drum to increase the removal efficiency. The conversion of gas flow from mist flow to annular flow is accomplished by subjecting the gas flow first to at least one expander and then tobends of various degrees and force the flow to change directions at least once. The change of gas flow from mist to annular helps coalesce fine liquid droplets and thus being removed from the vapor phase.

Description

The process for steam cracking of heavy hydrocarbon feedstocks

Background of invention

Invention field

The present invention relates to contain the cracking of the hydrocarbon of nonvolatile relatively hydrocarbon and other pollutent.

Background and description of related art

It is alkene that steam cracking is used to various hydrocarbon feed crackings for a long time.The stove with two main region is adopted in conventional steam cracking: convection section and radiant section.Hydrocarbon feed enters the convection section of stove usually with liquid form (unless the light raw material that enters with the steam form), at this, hydrocarbon feed usually by with from the hot flue gases indirect contact of radiant section be heated and vaporize by directly contacting with steam.Then, the raw material and the vapour mixture of vaporization enter radiant section, at this cracking take place.The product of gained comprises that alkene leaves pyrolysis oven, in order to further downstream processing such as quenching.

It is effective that conventional steam cracking system contains the high-quality raw materials of vast scale lightweight volatile hydrocarbon such as gas oil and petroleum naphtha for cracking.Yet the steam cracking economy is wished the heavy feed stock of cracking cheapness sometimes, as crude oil and the atmospheric resids (atmospheric resid) as limiting examples.Crude oil and atmospheric resids contain the high-molecular weight nonvolatile element that boiling point is higher than 1100 (590 ℃).The nonvolatile element of these raw materials at the convection section of conventional pyrolysis oven as under the sedimentation of coke.In the convection section in the some downstream of vaporizing fully, only can allow the very nonvolatile element of low levels than light constituent.In addition, some petroleum naphtha is contained the heavy crude pollution of nonvolatile element in transportation.Conventional pyrolysis oven does not have processing Residual oil, crude oil or by the handiness of the gas oil of many Residual oils or crude oil pollution or petroleum naphtha, these above-mentioned oil are polluted by the nonvolatile element hydrocarbon.

In order to solve this coking problem, United States Patent (USP) 3,617,493 (this document is combined in herein by reference) disclose the outside vaporization tank that is used for crude oil material, and disclose and utilize first flash distillation to remove petroleum naphtha with the steam form, utilize second flash distillation to remove the steam that boiling point is 450 to 1100 (230 to 600 ℃).The cracking in pyrolysis oven of described steam is an alkene, and isolating liquid is removed from two flash drums, uses steam stripped and is used as fuel.

United States Patent (USP) 3,718,709 (this document is combined in herein by reference) disclose the method that minimizes sedimentation of coke.It discloses the inner or outside preheating heavy feed stock at pyrolysis oven, to vaporize about 50% heavy feed stock and remove remaining, isolating liquid with superheated vapour.The hydrocarbon that mainly contains the vaporization of lightweight volatilization hydrocarbon is carried out cracking.

United States Patent (USP) 5,190,634 (this document is combined in herein by reference) disclose by preheating material in the presence of the hydrogen of convection section in a spot of, critical amount, suppress the method for coke formation in the stove.The existence of hydrogen has suppressed the polyreaction of hydrocarbon in the convection section, has suppressed coke formation thus.

United States Patent (USP) 5,580,443 (this document is combined in herein by reference) disclose a kind of method, and wherein raw material at first is preheated, and then by from the preheater of the convection section of pyrolysis oven, extracting out.The raw material of this preheating mixes with predetermined quantity of steam (dilution steam generation) then, and is introduced into gas-liquid separator then, to separate from separator and to remove the non-volatile matter of required ratio with liquid form.Turn back to from the steam of gas-liquid separator separates that pyrolysis oven heats and cracking.

The inventor recognizes, when using flash distillation that the heavy liquid hydrocarbon-fraction is separated with the lighter fraction that can handle in pyrolysis oven, importantly carries out described separation and makes most nonvolatile element be liquid phase.Otherwise the nonvolatile element of the heavy in steam, formation coke will be brought in the described stove, cause coking problem.

The inventor also recognizes, when using flash distillation that nonvolatile element is not caused that with handling the lighter fraction of the hydrocarbon feed of coking problem separates in pyrolysis oven, importantly controls the gas-liquid ratio when leaving flasher carefully.Otherwise the valuable lighter fraction possible loss of hydrocarbon feed is in the liquid hydrocarbon Residual oil, or component heavy, that form coke may be vaporized and be brought in the described stove as overhead product, causes coking problem.

Owing to relate to many variablees, the gas-liquid ratio of having found to be difficult to when leaving flasher is controlled.Gas-liquid ratio is the function of hydrocarbon partial pressure in flasher, also is the function that enters the temperature of the logistics in the flasher.The temperature that enters the logistics in the flasher changes along with the load variations of described stove.When described stove at full capacity the time temperature higher, and temperature is lower when described stove is in sub-load.The temperature that enters the logistics in the flasher also changes according to effluent gas temperature in the described stove of the described raw material of heating.And effluent gas temperature changes according to the coking degree that has taken place in described stove.When described stove be cleaning or very during slight coking, the temperature when effluent gas temperature is lower than the serious coking of described stove.Described effluent gas temperature still is applied to the function of the burning control on the burner of described stove.When described stove so that low-level excess of oxygen is operated in stack gas, then be lower than when the corresponding temperature of described stove so that the higher level excess of oxygen is operated in stack gas at middle part to the effluent gas temperature in the top region of convection section.Because all these variablees, so be difficult to control constant gas-liquid ratio when leaving flasher.

The invention provides a kind of advantageously method of control,, and reduce and avoid coking problem with the cracking of optimization contained volatile hydrocarbon in heavy hydrocarbon feedstocks.The invention provides the relative constant temp of logistics that enters flasher by keeping, keep leaving the method than constant gas-liquid ratio of flasher.More particularly, by the quantity of automatic adjusting before flash distillation, keep the steady temperature of flash stream with heavy hydrocarbon feedstocks blended fluid stream.Described fluid randomly is a water.

The present invention also provides a kind of method that keeps the relative constant hydrocarbon partial pressure of flash stream.Ratio by control flashing pressure and fluid and steam and hydrocarbon feed keeps the constant hydrocarbon partial pressure.

The invention summary

The invention provides a kind of method that heats heavy hydrocarbon feedstocks, it comprises the heating heavy hydrocarbon, described heavy hydrocarbon is mixed a kind of mixture of formation with fluid, the described mixture of flash distillation forms vapor phase and liquid phase, and change with described heavy hydrocarbon blended fluidic quantity with described vapor phase according to the operating parameters of at least a selection of described method and to be fed in the stove.But described fluid liquid hydrocarbon or water.

According to an embodiment, but the temperature of the heavy hydrocarbon of the heating before at least a operating parameters flash distillation.At least a operating parameters is at least a in the flow velocity of the temperature of flashing pressure, flash stream, flash stream and the excessive oxygen in stack gas also.

In a preferred embodiment, described heavy hydrocarbon mixed with the first dilution steam generation logistics before flash distillation.And, can in described stove, carry out heating to second dilution steam generation, then it is mixed with described heavy hydrocarbon.

The present invention also provide a kind of in stove the method for cracking heavy hydrocarbon feedstocks, described stove comprises the convection section that the radiant section of radiant heat and hot flue gases burner is provided and comprises a plurality of heat exchanger tube pipes rows, described method comprises:

(a) the described heavy hydrocarbon feedstocks of preheating is to form the heavy hydrocarbon feedstocks of preheating;

(b) heavy hydrocarbon feedstocks with described preheating mixes with water, forms the mixture of water and heavy hydrocarbon;

(c) first dilution steam generation is injected in the mixture of described water and heavy hydrocarbon, forms mixture stream passes;

(d) in heat exchanger tube pipe row, described mixture stream passes is heated, form the mixture stream passes of heat by indirect heat exchange with hot flue gases;

(e) temperature of the mixture stream passes of control heat, and the flow of the flow by changing water and first dilution steam generation is controlled the ratio of steam and hydrocarbon;

(f) mixture stream passes of the described heat of flash distillation forms vapor phase and liquid phase in flash drum, and with described vapor phase and liquid phase separation;

(g) described vapor phase is fed in the convection section of described stove, with by from the hot flue gases of the radiant section of described stove further to its heating, form vapor phase through heating; With

(h) during the Department of Radiation that described vapor phase through heating is fed to described stove was in charge of, owing to photothermal effect, the hydrocarbon thermally splitting in vapor phase formed product at this.

Brief Description Of Drawings

Figure 1 shows that the block diagram, particularly convection section of the inventive method that adopts steam cracker furnace.

Detailed Description Of The Invention

Unless otherwise noted, all percentage, umber, ratio etc. all are as the basis take weight. Unless otherwise noted, comprise compound or component itself when mentioning compound or component, and and its The combination of its compound or component such as the mixture of compound.

In addition, when quantity, concentration or other value or parameter with a series of upper limit preferred value and lower limit When preferred value provides, this should be understood to specifically disclose any a pair of upper limit preferred value and lower limit excellent All scopes that the choosing value forms are no matter whether described scope is by separately open.

When here using in addition: nonvolatile element can be tested according to following method: hydrocarbon feed Boiling point distribution is suitable with gas-chromatography distillation (GCD) or another kind according to ASTM D-6352-98 Method is measured. Nonvolatile element is the nominal boiling point according to ASTM D-6352-98 test (nominal boiling point) is higher than the hydrocarbon fraction of 1100 °F (590 ℃). The present invention couple The non-volatile matter effect that is higher than 1400 °F (760 ℃) in the nominal boiling point is very good.

The present invention relates to heat the method with the steam cracking heavy hydrocarbon feedstocks. Described method comprises heating Heavy hydrocarbon mixes a kind of mixture of formation with described heavy hydrocarbon with fluid, the described mixture of flash distillation comes Form vapor phase and liquid phase and change according to the operating parameter of at least a selection of described method The quantity of the fluid that mixes with described heavy hydrocarbon.

As can be noted, described raw material comprises vast scale, i.e. about heavy of 5 to 50% non-waving The property sent out component. As nonrestrictive example, such raw material can comprise a kind of in following or Multiple: steam cracked gas oil and residue, gas oil, fuel oil, jet fuel, diesel oil, Kerosene, gasoline, coking naphtha, steam cracking naphtha, catalytic cracking naphtha, hydrogenation split Change product, reformate, Residual oil reformate, Fischer-Tropsch liquid, Fischer-Tropsch gas, natural gasoline, distillation, Straight-run naphtha, crude oil, normal pressure fractioning pipestill Residual oil, comprise the decompression fractioning pipestill of Residual oil The naphtha of logistics, wide boiling range to the gas oil concentrate, from the non-straight run hydrocarbon stream of the heavy of refinery, The naphtha of vacuum gas oil, heavy gas oil, crude oil pollution, atmospheric resids, heavy still bottoms, C4/ residue mixture and naphtha residue mixture.

Described heavy hydrocarbon feedstocks has the nominal final boiling point of at least 600 °F (315 ℃). Preferably former Material is the naphtha of low sulfur waxy resids, atmospheric resids and crude oil pollution. Most preferably comprise 60-80% boiling point is lower than the Residual oil of the component of 1100 °F (590 ℃), for example low sulfur waxy resids.

Heavy hydrocarbon feedstocks at first is preheated in top convection part 3. Described heavy hydrocarbon feedstocks Heating can be adopted any form known to persons of ordinary skill in the art. Yet, preferred described heating Comprise described raw material in the top of described stove 1 convection part 3 with from the radiant section of described stove The mediate contact of hot flue gases. As non-limiting example, this can be by making feed stream through being positioned at Heat-exchange tube pipe row 2 in the convection part 3 of described stove 1 realizes. Described raw material through preheating Temperature be 300 to 500 °F (150 to 260 ℃). The temperature of preferred described raw material through heating Be about 325 to 450 °F (160 to 230 ℃) more preferably 340 to 425 °F (170 to 220 ℃).

Described hydrocarbon feed through preheating mixes with a kind of fluid. Described fluid can be liquid hydrocarbon, water, Steam or their mixture. Preferred fluid is water. The temperature of described fluid can be lower than, equal Or be higher than the temperature of described raw material through preheating.

Described heavy hydrocarbon feedstocks through preheating and described fluid mix can be in the inside of pyrolysis oven 1 or Carry out the outside, but preferably carry out in the outside of described stove. Can use any mixing known in the art Device is realized described mixing. Yet, preferred first distributor that uses two distributor assemblys 9 4 carry out described mixing. It is many that described first distributor 4 preferably includes the inside that is centered on by outer tube 32 Hole pipe 31, thus be formed on described in and the annularly flow space 33 between the outer tube. Preferably, Described heavy hydrocarbon feedstocks through preheating flows in described annularly flow space, and described flow warp Described inner tube and warp opening, the preferred small sircle hole in inner tube is injected in the described raw material. Institute is provided State first distributor 4 and be for described fluid is incorporated into described in the heavy hydrocarbon feedstocks of preheating The time, avoid or reduce the caused vibration of unexpected gasification (hammering) by fluid.

The present invention uses steam stream in the each several part of described method. As detailed in the following, first Dilution steam generation logistics 17 mixes with heavy hydrocarbon feedstocks through preheating. In a preferred embodiment, The second dilution steam generation logistics 18 is processed in convection part, and before described flash distillation with described heavy The matter hydrocarbon fluid mixes with the mixture of first dilution steam generation. Described second dilution steam generation, 18 optional branches Become reject steam 21 and flash-off steam 19.

In a preferred embodiment of the invention, except mixed with described heavy charge through preheating Beyond the fluid that closes, first dilution steam generation 17 also mixes with described raw material. Described first dilution is steamed The vapour logistics can preferably be injected in second distributor 8. Preferably at the logistics mixture that forms 11 Enter convection part with before heating in addition by radiant section flue gas, first dilution is steamed The vapour logistics is injected in the described heavy hydrocarbon fluid mixture. More preferably, described first dilutes steaming Vapour is directly injected in second distributor 8, the described distributor so that described first dilution steam generation is flowed through, And be injected in the described hydrocarbon feed fluid mixture through little circular flow distribution hole 34.

The temperature of described first dilution steam generation can greater than, less than or approximate greatly the heavy hydrocarbon feedstock stream body The temperature of mixture, but be preferably greater than the temperature of described mixture, and be used for making described raw material/stream Body mixture partial gasification. Preferably, in being injected into described second distributor 8 before, make institute It is overheated to state first dilution steam generation.

With leave the described fluid of described second sparger 8, through the mixture of the heavy hydrocarbon feedstocks of preheating and the first dilution steam generation logistics in heating once more in described pyrolysis oven 3 before the flash distillation.As non-limiting example, the heat exchanger tube pipe row 6 of the convection section that described heating can be by flowing through described raw mix to be positioned at described stove, thus heat and realize by hot flue gases from the radiant section of described stove.So the mixture of heating leaves described convection section as mixture stream passes 12, further to mix with additional steam stream.

Randomly, the described second dilution steam generation logistics 18 can further be divided into before flash distillation and described heavy hydrocarbon mixture 12 blended flash-off steam logistics 19, cross the reject steam logistics 21 of described heavy hydrocarbon mixture flasher with by-pass, described reject steam logistics 21 is mixing before the cracking in the radiant section of this vapor phase at described stove with the vapor phase from flasher.The present invention can not operate as under the condition of reject steam 21 as flash-off steam 19 at all second dilution steam generations 18.As selectable replacement scheme, the present invention can not operate second dilution steam generation 18 has the condition of flash-off steam 19 as reject steam 21 under.In a preferred embodiment of the invention, flash-off steam logistics 19 should be preferably 1: 20 to 20: 1 with the ratio of reject steam logistics 21, most preferably 1: 2 to 2: 1.Carry out in flash drum 5 before the flash distillation, described flash-off steam 19 mixes with described heavy hydrocarbon mixture stream passes 12 and forms flash stream 20.Preferably, separately and with before described heavy hydrocarbon mixture mixes, make the described second dilution steam generation logistics overheated in the described second dilution steam generation logistics in the superheater part 16 in described stove convection section.In described heavy hydrocarbon mixture stream passes 12, add flash-off steam logistics 19, guaranteed almost all gasifications of volatile constituent of described mixture before described flash stream 20 enters described flash drum 5.

Mixture (flash stream 20) with fluid, raw material and the first dilution steam generation logistics is incorporated in the flash drum 5 then, to be separated into two-phase: mainly comprise the vapor phase of volatile hydrocarbon and mainly comprise the liquid phase of fixed hydrocarbon.Vapor phase preferably shifts out from flash drum as overhead vapor stream 13.The convection section 23 of bottom that preferably described vapor phase is turned back to described stove is with the heating chosen wantonly with through the radiant section of communicating pipe to pyrolysis oven, to carry out cracking.Isolated liquid phase is removed from flash drum 5 as residual stream 27.

Preferably in flash drum 5, keep predetermined constant vapour-liquid ratio.But this ratio is difficult to measure and control.As a kind of selectable scheme, the temperature of the mixture stream passes 12 before flash drum 5 is as the indirect parameter of measuring, control and remain on constant vapour-liquid ratio in the flash drum 5.Ideally, when the temperature of described mixture stream passes was higher, more volatile hydrocarbon can gasify and can be used as vapor phase and be used for cracking.Yet when the temperature of described mixture stream passes was too high, more heavy hydrocarbon can be present in the vapor phase, and is carried in the convection coil finally coking on described pipe.If the temperature of described mixture stream passes 12 is too low, therefore gas-liquid ratio is low in flash drum 5, and then more volatile hydrocarbon will be retained in the liquid phase, and therefore can not be used for cracking.

The temperature of described mixture stream passes is subjected to the high-recovery/vaporization rate of volatile matter in the raw material to avoid in described boiler tube coking simultaneously or coking limits in the pipe of described mixture and the container being carried to described stove 13 by flash drum.Can monitor pipe and pressure drop in the container and the pressure drop in communicating pipe 24 at the convection section 13 that described mixture is sent to the bottom, and the rising of the temperature in the convection section 23 of bottom, to find out the beginning of coking problem.For example, when communicating pipe pressure and when the technology intake pressure of the convection section 23 of bottom begins to increase fast owing to coking, should be reduced in the temperature of flash drum 5 neutralise mixt logistics 12.If in the convection section of bottom, coking occurs, increase to the temperature of the stack gas of superheater 16, need more desuperheater water (desuperbeater water) 26.

The selection of the temperature of mixture stream passes 12 is also by deciding forming of raw material.When raw material contains the light hydrocarbon of higher amount, the temperature of described mixture stream passes 12 can be provided with lower.As a result, the amount of fluidic amount increase of using in first sparger 4 and/or the dilution steam generation that uses in second sparger 8 reduces, because these quantity directly influence the temperature of described mixture stream passes 12.When described raw material contains the fixed hydrocarbon of higher amount, the temperature of described mixture stream passes 12 should be provided with higher.As a result, the fluidic amount of using in first sparger 4 reduces and the amount of first dilution steam generation of use increase in second sparger 8.By the temperature of careful selection mixture stream passes, the present invention can be used for the raw material of wide kind scope.

Usually, the temperature of described mixture stream passes 12 is set and is controlled at 600 to 950 °F (315 to 510 ℃), preferred 700 to 920 (370 to 490 ℃), more preferably 750 to 900 (400 to 480 ℃), most preferably 810 to 890 (430 to 475 ℃).As discussed above, these numerical value can change with the concentration of volatile matter in the raw material.

Control the temperature of mixture stream passes 12 by Controlling System 7, described Controlling System 7 comprises at least one temperature sensor and any known control device such as computer.Preferably, temperature sensor is a thermopair.Described Controlling System 7 is communicated with the fluid valve 14 and first dilution steam valve 15, thus control enter two in the sparger fluid and the amount of first dilution steam generation.

In order to keep the steady temperature of mixture stream passes 12 of mixing with flash-off steam 19 and entering flash drum to be implemented in the constant vapour-liquid ratio in the flash drum 5, and avoid the considerable change of temperature and flashed vapour liquor ratio, the present invention operates as follows: when having set the temperature of the mixture stream passes 12 before flash drum 5, Controlling System 7 is controlled at two fluid valve 14 and first dilution steam valve 15 on the sparger automatically.When Controlling System 7 detected the temperature decline of mixture stream passes, it can make fluid valve 14 reduce the fluid that is injected in first sparger 4.If the temperature of mixture stream passes begins to rise, described fluid valve can be opened biglyyer, is injected into fluid in first sparger 4 with increase.In this embodiment preferred, the temperature of fluidic gasification latent heat control mixture stream passes.

When the first dilution steam generation logistics 17 was injected in second sparger 8, described temperature controlling system 7 also can be used for controlling first dilution steam valve 15, was injected into the amount of the first dilution steam generation logistics in second sparger 8 with adjusting.This has also reduced the drastic change of temperature variation in flash drum 5.When the temperature that detects mixture stream passes 12 when Controlling System 7 descended, it can order first dilution steam valve 15 to increase by the first dilution steam generation logistics of injecting in second sparger 8, and to close degree bigger for valve 14 simultaneously.Temperature begins to rise as described, and first dilution steam valve can be closed more automatically with minimizing and is injected into the first dilution steam generation logistics in second sparger 8, and valve 14 is opened biglyyer simultaneously.

In a preferred embodiment of the invention, Controlling System 7 can be used for controlling to join two in the sparger the fluidic amount and the amount of the first dilution steam generation logistics.

At described fluid is under the preferable case of water, and the amount that described controller changes the water and first dilution steam generation keeps constant mixture stream passes 12 temperature, keeps constant water and raw material ratio simultaneously in mixture 11.For further avoiding the rapid variation of flash vaporization point, the present invention also preferably adopts intermediate superheating steam cooling device 25 in the overheated zone of second dilution steam generation of described stove.This makes can be controlled at constant value with superheater 16 temperature outs, and the not variation of the variation of pipe furnace load, coking degree change, excess of oxygen level.Usually, this desuperheater 25 guarantees that the temperature of second dilution steam generation is between 800 to 1100 °F (430 to 590 ℃), between preferred 850 to 1000 °F (450 to 540 ℃), between more preferably 850 to 950 °F (450 to 510 ℃), between most preferably 875 to 925 °F (470 to 500 ℃).Described desuperheater is control valve and water atomizer nozzle preferably.After the part preheating, second dilution steam generation is discharged described convection section, and the mist of water 26 is added the quick also reduction temperature that gasifies of described mist.In convection section, described steam is further heated then.The amount of the water that adds in superheater has been controlled the temperature with mixture stream passes 12 blended steam.

Though preferably be adjusted in the fluid that is injected in two

spargers

4 and 8 in the heavy hydrocarbon feedstocks and the amount of the first dilution steam generation logistics according to the preset temperature of the described mixture stream passes 12 before flash drum 5, identical control mechanism also may be used in other locational other parameter.For example, can change the flow of flashing pressure and temperature and flash-off steam 19, realize the variation of vapour-liquid ratio in the flasher.In addition, the excess of oxygen in stack gas also can be a controlled variable, though be a slower variable.

Except that maintenance enters the steady temperature of the described mixture stream passes 12 in the flash drum, also wish to keep the constant hydrocarbon partial pressure of flash stream 20, to remain on constant vapour-liquid ratio in the flasher.For instance, can keep constant flash drum pressure, and, keep the constant hydrocarbon partial pressure by being controlled at the ratio of steam and hydrocarbon feed in the logistics 20 by using the control valve 36 on vapor phase pipeline 13.

Usually, the hydrocarbon partial pressure of flash stream is set and is controlled between 4 to 25psia (25 to the 175kPa) among the present invention, between preferred 5 to 15psia (35 to the 100kPa), most preferably between 6 to 11psia (40 to the 75kPa).

Described flash distillation is carried out at least one flash drum container.Preferably, described flash distillation is to have the one-stage process that refluxes or do not take back stream.The operation under the pressure of 40 to 200psia (275 to 1400kPa) usually of described flash drum 5, its temperature are generally equal to or a little less than the temperature that enters the flash stream 20 before the flash drum 5.Usually, the pressure of flash drum container is about 40 to 200psia (275 to 1400kPa), and temperature is about 600 to 950 °F (310 to 510 ℃).Preferably, the pressure of flash drum container is about 85 to 155psia (600 to 1100kPa), and temperature is about 700 to 920 °F (370 to 490 ℃).More preferably, the pressure of described flash drum container is about 105 to 145psia (700 to 1000kPa), and temperature is about 750 to 900 °F (400 to 480 ℃).Most preferably, the pressure of flash drum container is about 105 to 125psia (700 to 760kPa), and temperature is about 810 to 890 °F (430 to 480 ℃).According to the temperature of flash stream, enter mixture common 50 to 95% of described flash drum 5, preferred 60 to 90%, more preferably 65 to 85%, most preferably 70 to 85% are gasified to the top of flash drum.

In one aspect, the described flash drum 5 that turns round is so that minimize in the temperature of the liquid phase of described container bottom, because too much heat can cause the coking of non-volatile matter in the liquid phase.In entering the flash stream of flash drum, use the second dilution steam generation logistics 18, reduced gasification temperature,, thereby reduced required liquidus temperature because it has reduced the dividing potential drop (promptly the steam of bigger molar fraction is a steam) of hydrocarbon.The flash drum bottom liquid 30 of a part of exterior cooling is looped back the flash drum container assists cooling new isolating liquid phase may also be helpful in the bottom of flash drum 5.Logistics 27 is transported to water cooler 28 by the bottom of flash drum 5 through pump 37.Be divided into recycle stream 30 and output logistics 22 through refrigerative logistics 29.The temperature of described recycle stream is 500 to 600 °F (260 to 320 ℃) ideally, preferred 505 to 575 (263 to 302 ℃), more preferably 515 to 565 (268 to 296 ℃), most preferably 520 to 550 (270 to 288 ℃).The amount of recycle stream should be the about 80 to 250% of the new isolating bottom liquid scale of construction in the flash drum, and is preferred 90 to 225%, and more preferably 95 to 210%, most preferably 100 to 200%.

On the other hand, also turn round described flash drum so that in flash drum the liquid stop/hold-time minimize.Preferably, described liquid phase via the minor diameter " boots shape structure " at the bottom of the flash drum (boot) or cylinder 35 discharge described container.Usually, the liquid phase residence time is less than 75 seconds in described container, preferably is less than 60 seconds, more preferably less than 30 seconds, most preferably is less than 15 seconds.In flash drum the stop/hold-time of liquid phase short more, few more in flash drum bottom coking appears.

In described flash distillation, vapor phase 13 contains the non-volatile matter that is less than 400ppm usually, preferably is less than 100ppm, more preferably less than 80ppm, most preferably is less than 50ppm.Described vapor phase is rich in volatile hydrocarbon (for example 55-70%) and steam (for example 30-45%) very much.The full boiling point of vapor phase is usually less than 1400 °F (760 ℃), preferably is lower than 1100 °F (600 ℃), more preferably less than 1050 °F (570 ℃), most preferably is lower than 1000 °F (540 ℃).By removing vapor phase continuously via the overhead product pipe in the described flash drum 5, described overhead product pipe is optional to be transported to centrifuge separator 38 with steam, removes the liquid of carrying secretly of trace by it.Described then steam flows into manifold, and it is assigned to described steam flow in the convection section of described stove.

The preferred temperature that in the convection section 23 of pyrolysis oven bottom, is superheated to for example about 800 to 1200 (430 to 650 ℃) of the vapor phase stream of from flash drum, removing continuously 13 by stack gas from the radiant section of described stove.Described then steam is imported into the radiant section of pyrolysis oven to carry out cracking.

The vapor phase stream 13 of removing from flash drum is mixed with reject steam logistics 21 before also can be randomly in the convection section 23 that is incorporated into the stove bottom.

Reject steam logistics 21 is the branch's steam stream from second dilution steam generation 18.Preferably, in division and with before the vapor phase of removing from flash drum 5 is mixed, described second dilution steam generation at first is heated in pyrolysis oven 3.In some applications, after by the division of described second dilution steam generation but with before vapor phase is mixed, described bypass steam can be once more by overheated.Reject steam 21 overheated with after vapor phase stream 13 is mixed, before entering radiant section, all components except that heavy constituent that has guaranteed the mixture in this part of described stove gasified.To bring up to 800 to 1200 °F (430 to 650 ℃) in the vapor phase temperature in the convection section 23 of bottom and also help the operation in radiant section, because the radiator tube metal temperature can reduce.This causes coking possibility less in radiant section.Superheated vapo(u)r is cracking in the radiant section of pyrolysis oven then.

By aforesaid explanation, those of ordinary skills can easily determine essential characteristic of the present invention, and under the condition that does not depart from the spirit and scope of the invention, can make various changes and improvements of the present invention to make it to be adapted to various uses and condition.For example, though embodiment preferred requires water is mixed with the raw material of preheating, also can use other fluid, for example petroleum naphtha in sparger.

The present invention will be illustrated by the following examples, and described embodiment is as representative and can not be interpreted as restriction to invention scope.Unless otherwise indicated, all percentage ratio, umber etc. are based on weight.

Embodiment 1

Simulate the engineering calculation of processing normal pressure pipe still Residual oil (APS) and crude oil by the present invention.Appended table 1 has been summed up the analog result of cracking Tapis APS Residual oil and Tapis crude oil in having plant-scale stove of flash drum.Very light component in crude oil plays similar steam, has reduced the dividing potential drop of heavy component.Thereby under the recovered temperature of 950 of nominals (510 ℃), described flash drum can be operated under the temperature than atmospheric resids low 100 (50 ℃).

Table 1

Normal pressure pipe still (APS) Residual oil and crude flashing groove mimic are summed up

APS Residual oil crude oil Fig. 1 label #

The convection current flow that feeds in raw material, k1b/ hour (t/h) 126 (57) 100 (45) n/a

(510 ℃) below 950 °F, wt% 70 93 n/a

Temperature before sparger, °F (℃) 400 (205) 352 (178) 4

Sparger discharge, k1b/ hour (t/h) 12 (5) 43 (20) 14

The first dilution steam generation flow, k1b/ hour (t/h) 18 (8) 8 (4) 17

The second dilution steam generation flow, k1b/ hour (t/h) 17 (8) 19 (9) 18

Desuperheater discharge, k1b/ hour (t/h) 6 (3) 6 (3) 26

The flash drum temperature, °F (℃) 847 (453) 750 (400) 5

Flash drum pressure, psig (kPag) 107 (740) 101 (694) 5

The raw material that gasifies in flash drum, wt% 74 93 5

The resistates of discharging, k1b/ hour (t/h) 33 (15) 7 (3) 22

Embodiment 2

Table 2 summed up for the flash distillation simulated performance of the C4 material blended Residual oil of two kinds of concentration.Under given flash vaporization point, pressure and steam rate, make the Residual oil that in described flash drum, gasifies increase about 0.25% with the C4 of described each per-cent of Residual oil blended.Thereby, in raw material, add C4 and can cause being gasified from the more hydrocarbon in the described Residual oil.

Table 2

C4/ Residual oil mixture flash distillation performance

Pure Residual oil mixture 1: mixture 2:

Residual oil+C4 Residual oil+C4

Residual oil wt% 100 94 89 in the convection current raw material

C4 wt% 06 11 in the convection current raw material

Initial boiling point, °F 991 327 244

Under 112psig

The Residual oil wt% that gasifies in flash distillation 65.0% 68.2% 70.8%

The total wt% that gasifies in flash distillation 65.0% 69.9% 74.0%

Temperature, °F 819 819 819

The Residual oil wt% that gasifies in flash distillation 70.0% 72.8% 75.1%

The total wt% that gasifies in flash distillation 70.0% 74.3% 77.8%

Temperature, °F 835 835 835

The Residual oil wt% that gasifies in flash distillation 75.0% 77.4% 79.4%

The total wt% that gasifies in flash distillation 75.0% 78.6% 81.7%

Temperature, °F 855 855 855

Claims

1. the method for cracking heavy hydrocarbon feedstocks in stove, described stove comprises the convection section that the radiant section of radiant heat and hot flue gases burner is provided and comprises a plurality of heat exchanger tube pipe rows, described heavy hydrocarbon feedstocks has at least 315 ℃ nominal full boiling point, and this method comprises:

(a) heat described heavy hydrocarbon, to form heated raw material;

(b) steam is introduced in the described heated raw material;

(c) before or after step (b), with being incorporated in the described heated raw material one of at least in liquid hydrocarbon and the water;

(d) to the described heated raw material of small part flash distillation, to form vapor phase and liquid phase from step (c);

(e) the described vapor phase of at least a portion is fed in the described radiant section; With

(f) the introducing speed that one of changes in the introducing speed of described steam and described liquid hydrocarbon and the water at least is to control the ratio of described vapor phase and described liquid phase.

2. the amount that one of the process of claim 1 wherein in the amount of described steam and described liquid hydrocarbon and the water at least respond described method at least a operating parameters change and change.

3. the change of at least a operating parameters of the described method of introducing rate response that one of the process of claim 1 wherein in the introducing speed of described steam and described liquid hydrocarbon and the water at least and changing is with the ratio of described vapor phase of stepless control and described liquid phase.

4. claim 2 or 3 method, wherein said operating parameters be in following one of at least: the temperature of described heated raw material when flash distillation; The pressure of described heated raw material when flash distillation; The flow of described heated raw material when flash distillation; The amount of the oxygen in the stack gas of described stove; The concentration of volatile matter in the described heavy hydrocarbon feedstocks; Flow velocity with flash stream.

5. claim 2 or 3 method also comprise the described at least a operating parameters of monitoring.

6. the method for claim 5 also comprises the temperature by described heated raw material before the monitoring flash distillation, monitors the ratio of described vapor phase and described liquid phase.

7. claim 1 or 2 method, wherein step (c) comprises water is incorporated in the described heated raw material.

8. the method for claim 7 also comprises the hydrocarbon partial pressure substantially constant that keeps described heated raw material.

9. but the method for claim 7 also comprises and uses evaporation of water heat to come controlled step (c) back the temperature of step (d) described heated raw material before.

10. claim 1 or 2 method, wherein step (a) takes place at described convection section.

11. the method for claim 1 or 2, wherein second dilution steam generation is by overheated at described convection section, mixed with described heated raw material from step (c) then.

12. the method for claim 11, wherein a part of described second dilution steam generation mixes with described heated raw material, and described second dilution steam generation of another part mixes with described vapor phase.

13. the method for claim 1 or 2, wherein in step (e) before, the described vapor phase of at least a portion is heated at described convection section, to form heated vapor phase.

14. the method for claim 13, the temperature of wherein said heated vapor phase is between 430 ℃ to 650 ℃.

15. the method for claim 1 or 2, wherein step (d) is carried out at least one flash drum.

16. the method for claim 15, wherein said at least one flash drum moves under the pressure of 275kPa to 1400kPa.

17. the method for claim 1 or 2 wherein uses two sparger assemblies to be incorporated in the described heated heavy hydrocarbon feedstocks one of at least in described steam and described water and the described liquid hydrocarbon.

The minimum vibration when 18. the method for claim 17, the wherein said pair of sparger assembly one of make in described liquid hydrocarbon and described water at least and to be incorporated in the described heated heavy hydrocarbon feedstocks.

19. the method for claim 1 or 2, wherein the quilt of at least a portion hydrocarbon in described vapor phase is in described radiant section cracking.

20. the method for claim 1 or 2, wherein the hydrocarbon of 50% weight to 95% weight in described heavy hydrocarbon feedstocks is in described vapor phase.

21. the method for claim 1 or 2, wherein the described heavy hydrocarbon feedstocks of 60% weight to 80% weight has the boiling point below 590 ℃.

22. the method for claim 1 or 2, wherein said vapor phase have the nominal full boiling point that is lower than 760 ℃.

23. the method for claim 1 or 2, wherein the temperature from the described heated raw material of step (c) is 315 ℃ to 510 ℃.

24. the method for claim 1 or 2, wherein said heavy hydrocarbon feedstocks comprise in following one or more: steam cracked gas oil and resistates, gas oil, oil fuel, rocket engine fuel, diesel oil, kerosene, gasoline, coking naphtha, the steam cracking petroleum naphtha, the catalytic cracking petroleum naphtha, isocrackate, reformate, the Residual oil reformate, Fischer-Tropsch liquid, Fischer-Tropsch gas, natural gasoline, distillment, virgin naphtha, crude oil, normal pressure pipe still Residual oil, comprise the decompression pipe still logistics of Residual oil, the petroleum naphtha of wide boiling range is to the gas oil enriched material, from the non-straight run hydrocarbon stream of the heavy of refinery, vacuum gas oil, heavy gas oil, the petroleum naphtha of crude oil pollution, atmospheric resids, heavy still bottoms, C4/ residue mixture and naphtha residue mixture.

25. the method for claim 1 or 2, wherein said heavy hydrocarbon feedstocks comprises low sulfur waxy resids.