CN103788990B - A kind of steam cracking method - Google Patents
A kind of steam cracking method Download PDFInfo
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- CN103788990B CN103788990B CN201210419871.8A CN201210419871A CN103788990B CN 103788990 B CN103788990 B CN 103788990B CN 201210419871 A CN201210419871 A CN 201210419871A CN 103788990 B CN103788990 B CN 103788990B
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Abstract
A kind of steam cracking method implemented in the cracking apparatus comprising pyrolyzer and quenching apparatus, described pyrolyzer comprises convection zone and radiation section, the method comprises: mixed with liquid cracking stock by the mixture of alkene, hydrogen and water vapour, and the cracking stock mixture obtained is heated in convection zone, cracking stock mixture is vaporized and is heated to cross-over temperature, then the cracking stock mixture of vaporization is added to radiation section and carries out the first scission reaction, obtain the first cleavage reaction product; Logistics containing alkene is mixed to carry out the second scission reaction in the exit of radiation section with the first cleavage reaction product, obtains the second cleavage reaction product, then the second cleavage reaction product is injected quenching apparatus and carry out refrigerated separation.Method according to the present invention can alleviate alkene as the coking of cracking stock in convection section in cracking furnace, and pyrolyzer can be run for a long time, stably; And can efficient recovery from the heat of the high-temperature split product of radiation section.
Description
Technical field
The present invention relates to a kind of steam cracking method.
Background technology
The low-carbon alkenes such as ethene, propylene and divinyl are the important foundation raw materials of petrochemical industry.At present, the method for low-carbon alkene is produced based on tube furnace cracking petroleum hydrocarbon vapor technique.According to statistics, in the world the ethene of about 99%, the propylene of more than 50% and more than 90% divinyl by this explained hereafter.
Ethylene unit is called with the production equipment that the deep cooling process for separating in steam cracking in pipe type cracking furnace technique and downstream thereof is set up for core technology.The nucleus equipment of this device is tube cracking furnace, and it is made up of convection zone and radiation section.Cracking stock and dilution water steam heat first respectively in heating tube in section of convection chamber, the two mix and the post-heating that gasifies to initial cleavage temperature (i.e. " cross-over temperature "), then enter radiant coil cracking.In industrial pyrolysis furnace radiation section, the boiler tube that some groups of configurations of usually having arranged are identical.Pass into cracking stock in boiler tube, boiler tube adopts outward by liquid fuel or gas fuel combustion institute liberated heat to heat tube wall, and by the heat transfer of tube wall, transfers heat to the cracking stock in boiler tube.
As everyone knows, cracking refers to bubble point oil hydrocarbon under the high temperature conditions, and the process of carbochain fracture or dehydrogenation reaction generation alkene and other products occurs.The object of cracking be produce ethene, propylene is master, simultaneously alkene and pyrolysis gasoline, diesel oil, the fuel wet goods product such as by-product butylene, divinyl.
In recent years, take divinyl as synthetic rubber and the synthetic resins fast development of monomer, the price of product butadiene also climbs up and up, and product butadiene also becomes the important source of profit of ethylene unit.The corresponding butadiene yield of different cracking stocks is also not quite similar, and for gas cracking stock (low-carbon alkanes of below C5), the yield of divinyl is lower, and in the cracking product of such as normal butane, the yield of divinyl is only about 4%; For liquid cracking stock (as petroleum naphtha, hydrogenation tail oil etc.), butadiene yield is relatively high, and in the cracking product of such as hydrogenation tail oil, the yield of divinyl is up to 7%.It has been generally acknowledged that for those can not as the alkene of cracking stock, the butadiene yield of some alkene is quite high, such as, the butadiene yield of maleic shockingly can reach 18%, if therefore wish to increase divinyl output, alkene can be carried out scission reaction as maleic is added to pyrolyzer.
Typically, the cracking section of ethylene unit is made up of some liquid cracking furnace and a gas pyrolyzer.The raw material of gas pyrolyzer is generally ethane, propane and C4 alkane etc., and the phase of these cracking stocks when charging is gas phase, vaporizes without the need to the convection zone at pyrolyzer, and the convection zone design of pyrolyzer is often relatively simple; The raw material of liquid cracking furnace is generally petroleum naphtha, diesel oil and hydrogenation tail oil etc., and because phase during these cracking stock chargings is liquid phase, need to vaporize at the convection zone of pyrolyzer, the design of the convection zone of this pyrolyzer is often relatively more complex.If wish the yield that can increase divinyl under normal conditions, just must consider the cracking of unsaturated hydrocarbons in liquid starting material pyrolyzer, reason is the quantity of gas pyrolyzer very little.
Generally speaking, the effect of the convection zone of pyrolyzer mainly contains two, and one is that two is the waste heats in recovered flue gas, to improve the thermo-efficiency of stove by cracking stock preheating, vaporization be superheated to initial cracking temperature (cross-over temperature).Therefore, convection zone has different heat exchanging segment arrangement modes according to different processing requirements under normal circumstances, roughly comprises following heat exchanging segment: raw material preheating section, oiler feed preheating section, dilution steam generation superheat section, extra high pressure steam superheat section and Hybrid Heating section.Along with the development of technology, the convection zone technology also development of pyrolyzer, one is that the hop count of convection section in cracking furnace gets more and more, and such as raw material preheating section can be divided into upper raw material preheating section, Raw preheating section and lower raw material preheating section according to the energy difference of fume afterheat; Two be dilution steam generation injection mode variation, adopt different steam injection modes according to the difference of raw material, as a steam injection and secondary steam injection.Different steam injection modes is adopted to be to prevent raw material in the coking of convection zone, for liquid starting materials such as petroleum naphtha, diesel oil and hydrogenation tail oils, the process of vaporization is there is in it in convection zone heat-processed, if there is alkene in raw material, then at the vaporization initial stage, olefin(e) centent in gas phase is higher, easily causes coking; Vaporizing latter stage, the hydrocarbon component in liquid phase is heavier, equally easily causes coking.But the convection zone of pyrolyzer is once occur serious coking, not only can have a strong impact on the heat transfer process of convection zone, and convection zone pressure drop can be caused suddenly to increase, thus reduce the output of pyrolyzer, when reaching a certain limit, pyrolyzer blowing out must be carried out mechanical decoking.Therefore need to develop a kind of new steam cracking method, to adapt to be mixed into the operation under olefin component operating mode in raw material.
Multiple different cracking stock is entered to the convection zone of pyrolyzer, in prior art, propose some embodiments.Such as, CN1077978A proposes a kind of method that convection zone adopts the cracking petroleum hydrocarbon vapor ethene of twice steam injection, the method adopts 3 dispensing methods to inject the feeding manner of primary steam and some injection secondary steam, pyrolyzer is made to adapt to lightweight material, also can adapt to heavy feed stock, and not need when raw material switches to change pipeline.The method of this patent application is only the change of steam injection mode, does not affect the quality of the final cracking yield of whole cracking technology and product.
CN1501898A proposes the method for a kind of Light feeds cracking in the pyrolyzer for the cracking of cracking heavy feedstocks, the method comprises to be sent into the feed entrance of a part of Light feeds in convection section in cracking furnace, and other Light feeds is sent into convection zone together with diluent gas.The method of this patent application solves when cracking stock is replaced by lightweight material by heavy feed stock, and how lightweight material enters the problem of pyrolyzer, makes lightweight material by being unlikely to there is excessive pressure drop during raw material preheating section.
US2009/0178956A1 proposes a kind of for reducing the method for liquid cracking stock in convection zone coking, the method is that liquid starting material is reduced its dividing potential drop by injected gas equivalent way when independent preheating, thus improve liquid starting material at vaporization rate mixed with dilution steam generation, thus the formation of delays liquid raw material coking omen body, reduce and even eliminate the coking of liquid starting material at convection zone.
Current steam cracking method all concentrates on and how to make pyrolyzer adapt to more raw material of different nature, and as from lightweight material to heavy feed stock etc., or how pyrolyzer slows down when using heavy feed stock or eliminate the generation of coking.But, do not relate in prior art and alkene is injected as part cracking stock the method that pyrolyzer carries out steam cracking, more do not relate to and how to solve the problem that coking can occur as part cracking stock injection pyrolyzer alkene.
Usually, the radiation section that cracking stock enters pyrolyzer after the convection zone preheating of pyrolyzer carries out scission reaction, and cracking stock raises at the radiation section endothermic temperature of pyrolyzer, thus scission reaction occurs, generate micromolecular cracking target product, as ethene, propylene and divinyl etc.And at high temperature there is secondary reaction generation non-targeted product in the splitting gas of the radiation section outlet of pyrolyzer, therefore, the yield being cooled fast by Pintsch process gas to avoid affecting target product owing to there is too much secondary reaction is needed in the radiation section outlet of pyrolyzer.The chilling of splitting gas can adopt direct quench and indirect quench, and cryogen directly contacts with splitting gas by direct quench exactly, and splitting gas is cooled rapidly; Indirect quench is exactly indirectly contacted with splitting gas by wall with cryogen, and splitting gas is cooled rapidly.Under normal circumstances, in order to reclaim the heat of Pintsch process gas, to improve the thermo-efficiency of pyrolyzer and to reduce product cost, all adopt rapid-cooling heat exchanger to carry out indirect chilling, namely utilize transfer line exchanger (TLE) carry out chilling to splitting gas and reclaim heat generation steam.
Summary of the invention
The object of the invention is, in order to overcome, alkene is injected as part cracking stock the problem that coking can occur pyrolyzer, a kind of new steam cracking method is provided.
The invention provides a kind of steam cracking method, the method is implemented in cracking apparatus, described cracking apparatus comprises pyrolyzer and quenching apparatus, described pyrolyzer comprises convection zone and radiation section, described method comprises: the mixture of alkene, hydrogen and water vapour mixes with liquid cracking stock by (1), and the cracking stock mixture obtained is heated in described convection zone, described cracking stock mixture is made to vaporize and be heated to cross-over temperature, then the cracking stock mixture of vaporization is added to radiation section and carries out the first scission reaction, obtain the first cleavage reaction product; (2) logistics containing alkene is mixed to carry out the second scission reaction in the exit of described radiation section with described first cleavage reaction product, obtain the second cleavage reaction product, then described second cleavage reaction product is injected described quenching apparatus and carry out refrigerated separation, wherein, the described logistics containing alkene is the mixture of alkene or alkene and hydrogen and/or water vapour.
According to described steam cracking method provided by the invention, in convection section in cracking furnace, in the process that cracking stock mixture is carried out heating, because the alkene in described cracking stock mixture adds together with water vapour with hydrogen, therefore, at the vaporization initial stage of described cracking stock mixture, hydrogen and water vapour can play diluting effect to gas phase, make the olefin(e) centent in gas phase relatively low, thus the coking even avoiding the vaporization initial stage to occur can be alleviated; And, in the vaporization latter stage of described cracking stock mixture, water vapour exists with the form of superheated vapour, can impel liquid cracking stock generation fast vaporizing, to make in cracking stock relatively many heavy constituents to be vaporized, thus reach and alleviating the object that coking occurs latter stage in vaporization.Therefore, alkene can be alleviated as the coking of cracking stock in convection section in cracking furnace according to described method provided by the invention, pyrolyzer can be run for a long time, stably.
And, as everyone knows, scission reaction is strong endothermic reaction, if small portion cracking stock directly can be injected the radiation section exit of pyrolyzer, the temperature of splitting gas can be reduced, to reach the object of the high temperature heat making full use of splitting gas while increasing cracking product.But, if directly the liquid cracking stock of routine to be injected the radiation section exit of pyrolyzer, because the cracking temperature in radiation section exit significantly can reduce due to the injection of liquid cracking stock, make the scission reaction process in radiation section exit can produce more liquid-phase pyrolysis product, thus add the coking rate of quenching apparatus, and then the cycle of operation of whole cracking apparatus can be affected.
For this reason, in described steam cracking method provided by the invention, by the mixture of alkene or alkene and hydrogen and/or water vapour being injected the radiation section exit of pyrolyzer, scission reaction can be there is after alkene mixes with the cleavage reaction product produced by radiation section, the cracking temperature required due to alkene itself is lower, and liquid-phase pyrolysis product can not be produced after olefin cracking, therefore, steam cracking method according to the present invention can not only the heat of high temperature of cleavage reaction product that produced by radiation section of effective recycling, increase cracking product, but also the coking of quenching apparatus can be slowed down.
In addition, in described method of the present invention, in convection section in cracking furnace, in order to obtain the equal effect alleviating coking, by being added together with alkene by a small amount of hydrogen, significantly can reduce the consumption of water vapour.
In addition, the present inventor found through experiments, when alkene contains a certain amount of 1-butylene and/or 2-butylene, carry out in the process of scission reaction at liquid cracking stock and alkene, for ethylene product, the copyrolysis effect of liquid cracking stock and alkene is negative, and namely the ethylene yield that obtains of the two mixed pyrolysis is lower than the two ultimate production of ethene of obtaining of independent cracking separately; And for product butadiene, the copyrolysis effect of liquid cracking stock and alkene is positive, namely the divinyl output that obtains of the two mixed pyrolysis is higher than the two ultimate production of divinyl of obtaining of independent cracking separately.Therefore, according to described steam cracking method provided by the invention, when described alkene contains a certain amount of 1-butylene and/or 2-butylene, the butadiene yield significantly improved can be obtained.
Other features and advantages of the present invention are described in detail in embodiment part subsequently.
Accompanying drawing explanation
Accompanying drawing is used to provide a further understanding of the present invention, and forms a part for specification sheets, is used from explanation the present invention, but is not construed as limiting the invention with embodiment one below.In the accompanying drawings:
Fig. 1 is schematic diagram and the flow direction of material schematic diagram that prior art comprises the cracking apparatus of pyrolyzer and quenching apparatus;
Fig. 2 is schematic diagram and the flow direction of material schematic diagram that the present invention comprises the cracking apparatus of pyrolyzer and quenching apparatus.
Description of reference numerals
1 liquid cracking stock 2 oiler feed 3 water vapour
4 high pressure steam 5 blower fan 6 drums
7 quenching apparatus 8 flue gases are across section 9 radiation section
10 convection zone 11 raw material preheating sections
12 oiler feed preheating section 13 dilution steam generation superheat sections
14 extra high pressure steam superheat section 15 Hybrid Heating sections
16 alkene 17 splitting gas house stewards
18 hydrogen
Embodiment
Below in conjunction with accompanying drawing, the specific embodiment of the present invention is described in detail.Should be understood that, embodiment described herein, only for instruction and explanation of the present invention, is not limited to the present invention.
In the present invention, when not doing contrary explanation, the noun of locality such as " upper and lower " of use typically refers to reference to shown in the drawings upper and lower; " inside and outside " refers to profile inside and outside relative to each parts itself.
Fig. 2 is schematic diagram and the flow direction of material schematic diagram of the cracking apparatus comprising pyrolyzer.Described cracking apparatus comprises pyrolyzer, quenching apparatus 7, drum 6, blower fan 5 and splitting gas house steward 17, and described pyrolyzer comprises convection zone 10 and radiation section 9.Cracking stock enters radiation section 9 through convection zone 10.In radiation section 9, by combustion of liquid fuel or geseous fuel institute liberated heat, the material obtained after convection zone 10 preheating by described cracking stock is heated scission reaction occurs further.In described radiation section 9 exit, described cleavage reaction product and vapor-phase thermal cracking raw material (i.e. the mixture of alkene or alkene and hydrogen and/or water vapour) are mixed, and again scission reaction is there is under the own temperature of the mixture obtained, then the reaction product obtained is injected quenching apparatus 7 to cool, be separated into splitting gas and steam.Steam enters in drum 6 and carries out gas-liquid separation, and isolated high pressure steam can enter convection zone and heat, and to obtain extra high pressure steam, isolated water can be used as the water coolant of quenching apparatus 7; Splitting gas enters the target product isolated in later separation device and want through splitting gas house steward 17.The high-temperature flue gas that radiation section 9 combustion produces enters convection zone 10 through flue gas across section 8.Described quenching apparatus 7 is preferably rapid-cooling heat exchanger, is also indirect quenching apparatus.
In order to make full use of the heat of the high-temperature flue gas from radiation section 9, the convection zone 10 of described pyrolyzer is provided with multiple sections for reclaiming heat usually.Usually, what described convection zone 10 can be provided with in raw material preheating section 11, oiler feed preheating section 12, dilution steam generation superheat section 13, extra high pressure steam superheat section 14 and Hybrid Heating section 15 is one or more.Described raw material preheating section 11 is generally used for carrying out preheating to cracking stock.Described oiler feed preheating section 12 is generally used for carrying out preheating to the oiler feed be supplied in drum 6.Described dilution steam generation superheat section 13 is generally used for carrying out preheating to dilution steam generation (as water vapour).Described extra high pressure steam superheat section 14 is generally used for the high pressure steam from drum 6 to carry out heating to obtain extra high pressure steam.Described Hybrid Heating section 15 is generally used for cracking stock to be heated to cross-over temperature.For these sections above mentioned, can arrange according to actual needs, such as, when described cracking stock need first to carry out preheating mix with other logistics (as dilution steam generation) again time, then need to arrange described raw material preheating section 11, on the contrary, then do not need to arrange described raw material preheating section 11.
And according to needs of production, described convection zone 10 can be provided with one or more raw material preheating section 11.In one embodiment, when described cracking stock is injected by multiply logistics, and per share logistics all needs in advance when preheating mixes mutually again, in described convection zone 10, arrange multiple raw material preheating section 11, each raw material preheating section 11 carries out preheating to one logistics respectively.In another embodiment, when described cracking stock needs to be preheated to higher temperature, and target temperature can not be preheated to through a raw material preheating section, need to arrange multiple raw material preheating section 11 in described convection zone 10, to carry out repeatedly preheating to described cracking stock.
According to needs of production, in order to obtain the extra high pressure steam of specified temp and pressure, one or more extra high pressure steam superheat section 14 can be set in described convection zone 10.
According to needs of production, in order to be heated to by cracking stock cross-over temperature to alleviate the load of radiation section, one or more Hybrid Heating section can be set in described convection zone 10.
In described pyrolyzer, when being provided with the plural section be selected from raw material preheating section 11, oiler feed preheating section 12, dilution steam generation superheat section 13, extra high pressure steam superheat section 14 and Hybrid Heating section 15 in described convection zone 10, position between each section can be determined according to actual needs, when the medium to be heated in a certain section needs the heating carrying out higher-strength, when being also namely heated to higher temperature, then this section can be arranged near the position of described flue gas across section 8, because relatively high across the temperature of the position flue gas of section 8 near described flue gas; When the medium to be heated in a certain section needs to carry out more low intensive heating, when being also namely heated to lower temperature, then this section can be arranged on away from the position of described flue gas across section 8 because from described flue gas across section 8 more away from the temperature of flue gas lower.Such as, in one embodiment, as shown in Figure 2, in described convection zone 10, along the flow direction of high-temperature flue gas, be disposed with Hybrid Heating section 15, extra high pressure steam superheat section 14, dilution steam generation superheat section 13, oiler feed preheating section 12 and raw material preheating section 11.
Steam cracking method according to the present invention is implemented in cracking apparatus, and described cracking apparatus comprises pyrolyzer and quenching apparatus 7, and described pyrolyzer comprises convection zone 10 and radiation section 9, said method comprising the steps of:
(1) mixture of alkene, hydrogen and water vapour is mixed with liquid cracking stock, and the cracking stock mixture obtained is heated in described convection zone, described cracking stock mixture is made to vaporize and be heated to cross-over temperature, then the cracking stock mixture of vaporization is added to radiation section and carries out the first scission reaction, obtain the first cleavage reaction product;
(2) logistics containing alkene is mixed to carry out the second scission reaction in the exit of described radiation section with described first cleavage reaction product, obtain the second cleavage reaction product, then described second cleavage reaction product is injected described quenching apparatus and carry out refrigerated separation, wherein, the described logistics containing alkene is the mixture of alkene or alkene and hydrogen and/or water vapour.
In the present invention, liquid cracking stock enters separately the process that described convection zone 10 carries out heat exchange, and at least one in alkene, hydrogen and water vapour enters the process that described convection zone 10 carries out heat exchange and is called warm, mixture and the liquid cracking stock of alkene, hydrogen and water vapour mix (also i.e. cracking stock mixture) enters the process that described convection zone 10 carries out heat exchange and is called heat-processed.
In a preferred embodiment, described method also comprises: before being mixed with liquid cracking stock by the mixture of alkene, hydrogen and water vapour, described liquid cracking stock is carried out preheating in described convection zone 10.According to this implementation method, by making liquid cracking stock carry out preheating in advance before mixing with the mixture of alkene, hydrogen and water vapour, the object alleviating coking further can be reached.Preferably, the temperature of described liquid cracking stock after the preheating of described convection zone 10 is 120-300 DEG C, is more preferably 150-250 DEG C.
In another embodiment, described method also comprises: before being mixed with liquid cracking stock by the mixture of alkene, hydrogen and water vapour, the mixture of alkene, hydrogen and water vapour is carried out preheating in described convection zone 10.The temperature of mixture after described convection zone preheating of described alkene, hydrogen and water vapour is preferably 480-560 DEG C, is more preferably 500-540 DEG C.
In step (1), the weight ratio of the consumption of described liquid cracking stock and water vapour can be 1-4:1, is preferably 1.5-2.5:1.
In step (1), the weight ratio of the consumption of described alkene and water vapour can be 1:1-30, is preferably 1:5-20.
In step (1), the weight ratio of the consumption of described liquid cracking stock and hydrogen can be 500-10000:1, is preferably 1000-4000:1.
In step (1), described first scission reaction is substantially identical with the scission reaction occurred in the radiation section 9 of pyrolyzer in conventional steam cracking method, and therefore, described first scission reaction can be implemented by crack reacting condition conveniently.In the preferred case, the condition of described first scission reaction comprises: described is 560-660 DEG C cross-over temperature, is preferably 580-640 DEG C; The temperature out of described radiation section is 780-850 DEG C, is preferably 790-840 DEG C; Namely the reaction times residence time of cracking stock mixture in described radiation section 9 of described vaporization (also) is 0.1-0.5 second, be preferably 0.2-0.3 second.
In another kind of preferred implementation, described method also comprises: before the described logistics containing alkene being mixed with described first cleavage reaction product, the described logistics containing alkene is carried out preheating in described convection zone 10.According to this embodiment, before mixing with described first cleavage reaction product, preheating is carried out in advance by making the logistics containing alkene, the temperature in radiation section exit can not be caused significantly to reduce after logistics containing alkene is injected, thus ensure that alkene more fully scission reaction can occur.Under preferable case, the described temperature 120-660 DEG C of logistics after described convection zone preheating containing alkene, is more preferably 150-620 DEG C.Further preferably, when the described logistics containing alkene is the mixture of alkene or alkene and hydrogen, the described temperature of logistics after described convection zone preheating containing alkene is 120-250 DEG C, is more preferably 150-200 DEG C; When the described logistics containing alkene is the mixture of the mixture of alkene and water vapour or alkene and hydrogen and water vapour, the described temperature of logistics after described convection zone preheating containing alkene is 500-660 DEG C, is more preferably 540-620 DEG C.
In above-mentioned various embodiment, each warm carried out in described convection zone 10 carries out respectively in the different sections of described convection zone 10.Particularly, the warm of described liquid cracking stock carries out in the raw material preheating section 11 of described convection zone 10.The mixture of described alkene, hydrogen and water vapour and the warm of the described logistics containing alkene carry out in the dilution steam generation superheat section 13 of described convection zone 10.
In the preferred embodiment of one, as shown in Figure 2, in described convection zone 10, liquid cracking stock 1 is carried out preheating through raw material preheating section 11, the mixture of one alkene 16, hydrogen 18 and water vapour 3 is carried out preheating through dilution steam generation superheat section 13 simultaneously, afterwards the liquid cracking stock through the preheating of described raw material preheating section 11 is mixed with the mixture of the alkene 16 through the preheating of described dilution steam generation superheat section 13, hydrogen 18 and water vapour 3, obtain cracking stock mixture; Then described cracking stock mixture is heated through Hybrid Heating section 15, so that cracking stock mixture is heated to cross-over temperature, then injects radiation section 9 and carry out scission reaction (being also the first scission reaction); Meanwhile, the mixture of another strand of alkene 16, hydrogen 18 and water vapour 3 is carried out preheating through dilution steam generation superheat section 13, obtain the logistics containing alkene through preheating; Then the described logistics containing alkene through preheating is mixed in the exit of described radiation section 9 with the cleavage reaction product produced by radiation section 9 (being also the first cleavage reaction product), and under the own temperature of the mixture obtained, carry out scission reaction (being also the second scission reaction); And then the final split product (being also the second cleavage reaction product) obtained is injected described quenching apparatus 7 and carry out refrigerated separation.
In addition, above-mentioned preferred embodiment in, in order to make full use of the heat of the high-temperature flue gas in described convection zone 10, optionally oiler feed 2 can be heated by oiler feed preheating section 12, and the high pressure steam 4 from drum 6 is heated by extra high pressure steam superheat section 14, obtain ultra-high voltage superheated vapour.In this preferred implementation, in described convection zone 10, along the flow direction of high-temperature flue gas, be preferably disposed with Hybrid Heating section 15, extra high pressure steam superheat section 14, dilution steam generation superheat section 13, oiler feed preheating section 12 and raw material preheating section 11.
In described method provided by the invention, in step (2), the described logistics containing alkene is preferably the mixture of alkene, hydrogen and water vapour.More preferably, the weight ratio of the consumption of described alkene and water vapour is 0.1-10:1, more preferably 0.5-2:1; The weight ratio of the consumption of described alkene and hydrogen is 50-1000:1, more preferably 80-400:1.
In described method provided by the invention, in step (2), the weight ratio of the alkene in the described logistics containing alkene and the consumption of described liquid cracking stock can be 0.001-0.2:1, is preferably 0.01-0.1:1.
In described method provided by the invention, in step (2), described second scission reaction is carried out under the own temperature of the mixture of the described logistics containing alkene and the cleavage reaction product produced by radiation section 9 (also i.e. the first cleavage reaction product).The time of described second scission reaction is shorter, can be less than 0.1 second, is preferably 0.001-0.05 second.
In described method provided by the invention, in step (1) and step (2), described alkene can be identical or different, and can be the alkene of various routine separately, such as, can be the alkene of C4-C6.In the preferred case, step (1) is identical with the described alkene of step (2), and all contains 1-butylene and/or the 2-butylene of more than 10 % by weight, more preferably all contains 1-butylene and/or the 2-butylene of more than 50 % by weight.Such alkene can be such as conventional hybrid C 4 alkene.When the described alkene of step (1) and step (2) comprises 1-butylene and/or the 2-butylene of above-mentioned content, method according to the present invention can not only the heat of high temperature of cleavage reaction product that produced by radiation section of effective recycling, the coking of convection zone can not to be caused owing to introducing alkene as part cracking stock, but also the yield of divinyl can be significantly improved.
In described method provided by the invention, described liquid cracking stock can be the various liquid cracking stocks that this area routine uses, such as, can be petroleum naphtha and/or hydrogenation tail oil.
The invention will be further described by the following examples.
Embodiment 1
The present embodiment is for illustration of described steam cracking method provided by the invention.
The cracking apparatus shown in Fig. 2 is adopted to carry out scission reaction.Detailed process comprises:
By as shown in table 2 for the petroleum naphtha 1(correlation parameter of 60 DEG C) carry out preheating through raw material preheating section 11; To form as shown in table 1 by hybrid C 4 alkene 16(simultaneously), the first burst of logistics mixing of hydrogen 18 and water vapour 3 carry out preheating through dilution steam generation superheat section 13; Then the petroleum naphtha through preheating is mixed with burst logistics of first through preheating, and the cracking stock mixture obtained is heated through Hybrid Heating section 15, then enter radiation section 9 and carry out scission reaction; Meanwhile, will form as shown in table 1 by hybrid C 4 alkene 16(), the second burst of logistics (also namely containing the logistics of alkene) that mix of hydrogen 18 and water vapour 3 carry out preheating through dilution steam generation superheat section 13; Then, in the exit of radiation section 9, second burst of logistics through preheating is mixed with the cleavage reaction product that the scission reaction by radiation section 9 produces, and carries out steam cracking reaction; Then, the final cleavage reaction product obtained is injected rapid-cooling heat exchanger 7 and carries out refrigerated separation, be separated into high pressure steam and splitting gas, splitting gas is entered later separation device through splitting gas house steward 17.Wherein, the charging capacity of petroleum naphtha 1 is 43130kg/h, and in first burst of logistics, the injection rate of water vapour is 22700kg/h, and the charging capacity of hybrid C 4 alkene is 2270kg/h, and the injection rate of hydrogen is 25kg/h; In second burst of logistics, the injection rate of water vapour is 2270kg/h, the charging capacity of hybrid C 4 alkene is 1362kg/h, the injection rate of hydrogen is 15kg/h, temperature through second burst of logistics of preheating is 520 DEG C, and the temperature through second burst of logistics of preheating is 600 DEG C, and (XOT) is 590 DEG C cross-over temperature, the temperature out (COT) of the radiation section of pyrolyzer is 830 DEG C, and the scission reaction time in radiation section 9 is 0.24 second.Other processing parameters of pyrolyzer and chilling heat-exchanger rig 7 are as shown in table 3, and learn by carrying out a point analysis of variance to splitting gas, the composition of splitting gas is as shown in table 4.
Table 1
Table 2
Table 3
Table 4
| Component | % by weight |
| Hydrogen | 0.88 |
| Methane | 11.82 |
| Ethane | 3.15 |
| Ethene | 27.63 |
| Acetylene | 0.33 |
| Propane | 0.46 |
| Propylene | 16.98 |
| Propine | 0.32 |
| Propadiene | 0.25 |
| Trimethylmethane | 0.01 |
| Normal butane | 0.34 |
| Butene-1 | 2.11 |
| Iso-butylene | 2.74 |
| Anti-butylene | 1.00 |
| Maleic | 1.52 |
| Divinyl | 5.88 |
| Other | 24.58 |
| Add up to | 100.00 |
Comparative example 1
Method according to embodiment 1 carries out steam cracking, and difference is, as shown in Figure 1, do not inject described hybrid C 4 alkene 16 and hydrogen 18 in first burst of logistics, and do not inject second burst of logistics, and the charging capacity of petroleum naphtha is 45400kg/h.Wherein, other processing parameters of pyrolyzer and chilling heat-exchanger rig 7 are as shown in table 5, and learn by carrying out a point analysis of variance to splitting gas, the composition of splitting gas is as shown in table 6.
Table 5
Table 6
| Component | % by weight |
| Hydrogen | 0.81 |
| Methane | 11.79 |
| Ethane | 3.38 |
| Ethene | 29.50 |
| Acetylene | 0.33 |
| Propane | 0.50 |
| Propylene | 16.94 |
| Propine | 0.32 |
| Propadiene | 0.24 |
| Trimethylmethane | 0.04 |
| Normal butane | 0.37 |
| Butene-1 | 2.11 |
| Iso-butylene | 2.93 |
| Anti-butylene | 0.00 |
| Maleic | 0.51 |
| Divinyl | 4.84 |
| Other | 25.39 |
| Add up to | 100.00 |
As can be seen from the data of table 4 and table 6, the butadiene yield of embodiment 1 is 5.88 % by weight, and the butadiene yield of comparative example 1 is 4.84 % by weight, namely butadiene yield is made to improve 21.49% by adding described hybrid C 4 alkene in the exit of radiation section 9 as part cracking stock in embodiment 1.
And in comparative example 1, Hybrid Heating section is 122.7kPa in the pressure drop of end-of-run; And in embodiment 1, Hybrid Heating section is 123.9kPa in the pressure drop of end-of-run, and after namely adding alkene in embodiment 1, Hybrid Heating section is 122.7kPa relative to comparative example 1(Hybrid Heating section in the pressure drop of end-of-run in the pressure drop of end-of-run) increase only 0.98%.
In addition, as can be seen from the data of table 3 and table 5, although the pressure drop of rapid-cooling heat exchanger between end-of-run outlet with entrance has a little increase relative to comparative example 1 (embodiment 1 is 24.3kPa/g in embodiment 1, comparative example 1 is 23.8kPa/g), but the temperature out of rapid-cooling heat exchanger declines all to some extent from initial stage to latter stage.
As can be seen here, according to described method provided by the invention, by introducing alkene as part cracking stock in convection zone 10, and introduce alkene in the exit of radiation section 9, can not only efficient recovery from the heat of the high-temperature split product of radiation section 9, but also do not cause blocking owing to producing serious coking in the convection zone of pyrolyzer and rapid-cooling heat exchanger, even also significantly improve butadiene yield.
Embodiment 2
The present embodiment is for illustration of described steam cracking method provided by the invention.
Method according to embodiment 1 carries out steam cracking, and difference is, the charging capacity of petroleum naphtha is 45400kg/h, and in first burst of logistics, the injection rate of water vapour is 22700kg/h, and the charging capacity of hybrid C 4 alkene is 1362kg/h, and the injection rate of hydrogen is 15kg/h; In second burst of logistics, the injection rate of water vapour is 2270kg/h, the charging capacity of hybrid C 4 alkene is 2270kg/h, the injection rate of hydrogen is 25kg/h, temperature through second burst of logistics of preheating is 540 DEG C, and the temperature through second burst of logistics of preheating is 560 DEG C, is 590 DEG C cross-over temperature, the temperature out (COT) of radiation section 9 is 830 DEG C, and the scission reaction time in radiation section 9 is 0.3 second.Other processing parameters of pyrolyzer and chilling heat-exchanger rig 7 are as shown in table 7, and learn by carrying out a point analysis of variance to splitting gas, the composition of splitting gas is as shown in table 8.
Table 7
Table 8
| Component | % by weight |
| Hydrogen | 0.89 |
| Methane | 11.81 |
| Ethane | 3.14 |
| Ethene | 27.64 |
| Acetylene | 0.33 |
| Propane | 0.47 |
| Propylene | 16.98 |
| Propine | 0.33 |
| Propadiene | 0.25 |
| Trimethylmethane | 0.01 |
| Normal butane | 0.35 |
| Butene-1 | 2.10 |
| Iso-butylene | 2.75 |
| Anti-butylene | 1.01 |
| Maleic | 1.52 |
| Divinyl | 5.85 |
| Other | 24.57 |
| Add up to | 100.00 |
Embodiment 3
The present embodiment is for illustration of described steam cracking method provided by the invention.
Method according to embodiment 1 carries out steam cracking, difference is, do not inject in second burst of logistics water vapour 3 and hydrogen 18(also namely this logistics be made up of described hybrid C 4 alkene), and the exit of radiation section 9 is injected in this second burst of logistics after convection zone 10 is preheated to 200 DEG C.Other processing parameters of pyrolyzer and chilling heat-exchanger rig 7 are as shown in table 9, and learn by carrying out a point analysis of variance to splitting gas, the composition of splitting gas is as shown in table 10.
Table 9
Table 10
| Component | % by weight |
| Hydrogen | 0.88 |
| Methane | 11.83 |
| Ethane | 3.14 |
| Ethene | 27.75 |
| Acetylene | 0.33 |
| Propane | 0.47 |
| Propylene | 17.10 |
| Propine | 0.33 |
| Propadiene | 0.26 |
| Trimethylmethane | 0.02 |
| Normal butane | 0.35 |
| Butene-1 | 2.13 |
| Iso-butylene | 2.75 |
| Anti-butylene | 1.03 |
| Maleic | 1.52 |
| Divinyl | 5.48 |
| Other | 24.63 |
| Add up to | 100.00 |
By table 3 and table 9 being compared and table 4 and table 10 being compared and can find out, according to described method provided by the invention, better effect can be obtained by the exit that the mixture of alkene, hydrogen and water vapour is injected radiation section 9 as the logistics containing alkene, particularly can obtain higher butadiene yield.
Claims (23)
1. a steam cracking method, the method is implemented in cracking apparatus, and described cracking apparatus comprises pyrolyzer and quenching apparatus, and described pyrolyzer comprises convection zone and radiation section, and described method comprises:
(1) mixture of alkene, hydrogen and water vapour is mixed with liquid cracking stock, and the cracking stock mixture obtained is heated in described convection zone, described cracking stock mixture is made to vaporize and be heated to cross-over temperature, then the cracking stock mixture of vaporization is added to radiation section and carries out the first scission reaction, obtain the first cleavage reaction product;
(2) logistics containing alkene is mixed to carry out the second scission reaction in the exit of described radiation section with described first cleavage reaction product, obtain the second cleavage reaction product, then described second cleavage reaction product is injected described quenching apparatus and carry out refrigerated separation, wherein, the described logistics containing alkene is the mixture of alkene or alkene and hydrogen and/or water vapour;
Wherein, in step (1), the weight ratio of the consumption of described alkene and water vapour is 1:1-30;
Wherein, in step (1), the weight ratio of the consumption of described liquid cracking stock and water vapour is 1-4:1;
Wherein, in step (1), the weight ratio of the consumption of described liquid cracking stock and hydrogen is 500-10000:1.
2. method according to claim 1, wherein, described method also comprises: before being mixed with liquid cracking stock by the mixture of alkene, hydrogen and water vapour, described liquid cracking stock is carried out preheating in described convection zone.
3. method according to claim 2, wherein, the temperature of described liquid cracking stock after described convection zone preheating is 120-300 DEG C.
4. method according to claim 3, wherein, the temperature of described liquid cracking stock after described convection zone preheating is 150-250 DEG C.
5. according to the method in claim 1-4 described in any one, wherein, described method also comprises: before being mixed with liquid cracking stock by the mixture of alkene, hydrogen and water vapour, the mixture of alkene, hydrogen and water vapour is carried out preheating in described convection zone.
6. method according to claim 5, wherein, the temperature of mixture after described convection zone preheating of described alkene, hydrogen and water vapour is 480-560 DEG C.
7. method according to claim 6, wherein, the temperature of mixture after described convection zone preheating of described alkene, hydrogen and water vapour is 500-540 DEG C.
8., according to the method described in claim 1, wherein, in step (1), the weight ratio of the consumption of described alkene and water vapour is 1:5-20.
9. method according to claim 1, wherein, in step (1), the weight ratio of the consumption of described liquid cracking stock and water vapour is 1.5-2.5:1.
10. method according to claim 1, wherein, in step (1), the weight ratio of the consumption of described liquid cracking stock and hydrogen is 1000-4000:1.
11. methods according to claim 1, wherein, the condition of described first scission reaction comprises: described is 560-660 DEG C cross-over temperature; The temperature out of described radiation section is 780-850 DEG C; Reaction times is 0.1-0.5 second.
12. methods according to claim 11, wherein, the condition of described first scission reaction comprises: described is 580-640 DEG C cross-over temperature; The temperature out of described radiation section is 790-840 DEG C; Reaction times is 0.2-0.3 second.
13. methods according to claim 1, wherein, described method also comprises: before the described logistics containing alkene being mixed with described first cleavage reaction product, the described logistics containing alkene is carried out preheating in described convection zone.
14. methods according to claim 13, wherein, the described temperature of logistics after described convection zone preheating containing alkene is 120-660 DEG C.
15. methods according to claim 14, wherein, the described temperature of logistics after described convection zone preheating containing alkene is 150-620 DEG C.
16. methods according to claim 15, wherein, the described logistics containing alkene is the mixture of alkene, hydrogen and water vapour.
17. methods according to claim 16, wherein, in step (2), the weight ratio of the consumption of described alkene and water vapour is 0.1-10:1; The weight ratio of the consumption of described alkene and hydrogen is 50-1000:1.
18. methods according to claim 17, wherein, in step (2), the weight ratio of the consumption of described alkene and water vapour is 0.5-2:1; The weight ratio of the consumption of described alkene and hydrogen is 80-400:1.
19. methods according to claim 15, wherein, the weight ratio of the alkene in the described logistics containing alkene and the consumption of described liquid cracking stock is 0.001-0.2:1.
20. methods according to claim 19, wherein, the weight ratio of the alkene in the described logistics containing alkene and the consumption of described liquid cracking stock is 0.01-0.1:1.
21. methods according to claim 18, wherein, in step (1) and step (2), described alkene contains 1-butylene and/or the 2-butylene of more than 10 % by weight.
22. methods according to claim 21, wherein, in step (1) and step (2), described alkene contains 1-butylene and/or the 2-butylene of more than 50 % by weight.
23. methods according to claim 20, wherein, described liquid cracking stock is petroleum naphtha and/or hydrogenation tail oil.
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| AT525775B1 (en) * | 2021-12-27 | 2024-09-15 | Wolfgang Bacher | Arrangement, refinery and process for producing hydrocarbons |
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