CN103787807B - A kind of steam cracking method - Google Patents
A kind of steam cracking method Download PDFInfo
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Abstract
A kind of steam cracking method, the method comprises: mixed with water vapour by liquid cracking stock, then be heated in convection zone cross-over temperature, enter radiation section afterwards and carry out scission reaction, then the cleavage reaction product obtained is injected quenching apparatus and carry out refrigerated separation, wherein, described method also comprises at least one in following two processes: (1) by heating after cracking stock mixture be added to radiation section before, by heating after cracking stock mixture and olefin; (2) before cleavage reaction product is injected quenching apparatus, cleavage reaction product and olefins contact are reacted.According to described method provided by the invention, by introducing alkene in the exit of radiation section and/or ingress, can not cause producing coking in the convection zone of pyrolyzer and quenching apparatus, and effective utilization of the heat to the high-temperature split product from radiation section can be realized, and improve butadiene yield.
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: mixed with water vapour by liquid cracking stock, and the cracking stock mixture obtained is heated to cross-over temperature in described convection zone, and the cracking stock mixture after heating is added to radiation section and carries out scission reaction, then the cleavage reaction product obtained is injected described quenching apparatus and carry out refrigerated separation, wherein, described method also comprises at least one in following two processes: (1) is before being added to radiation section by the cracking stock mixture after described heating, by the cracking stock mixture after described heating and olefin, (2) before described cleavage reaction product is injected described quenching apparatus, described cleavage reaction product and olefins contact are reacted.
In described steam cracking method provided by the invention, in process (1), alkene adds in the ingress of radiation section, therefore alkene add can't cause pyrolyzer convection zone in occur coking.And, in the radiation section of pyrolyzer, alkene can with liquid cracking stock generation copyrolysis, can obtain higher butadiene yield, particularly, when alkene contains a certain amount of 1-butylene and/or 2-butylene, butadiene yield can be significantly improved.
In described steam cracking method provided by the invention, for process (2), 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 process (2), by alkene 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, process (2) in described steam cracking method of the present invention effectively can not only utilize the heat of high temperature of the cleavage reaction product produced by radiation section, increase cracking product, but also the coking of quenching apparatus can be slowed down.
In addition, in step (2), by adding alkene in radiation section exit, copyrolysis can be there is further in alkene with the split product from radiation section, produce divinyl, thus higher butadiene yield can be obtained, particularly, when alkene contains a certain amount of 1-butylene and/or 2-butylene, butadiene yield can be significantly improved.
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
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, rapid-cooling heat exchanger 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.Split product injects rapid-cooling heat exchanger 7 and cools, and is 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 rapid-cooling heat exchanger 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, described cracking apparatus comprises pyrolyzer and quenching apparatus 7, described pyrolyzer comprises convection zone 10 and radiation section 9, described method comprises: mixed with water vapour by liquid cracking stock, and the cracking stock mixture obtained is heated to cross-over temperature in described convection zone 10, and the cracking stock mixture after heating is added to radiation section 9 and carries out scission reaction, then the cleavage reaction product obtained is injected described quenching apparatus 7 and carry out refrigerated separation, wherein, described method also comprises at least one in following two processes:
(1) before the cracking stock mixture after described heating is added to radiation section, by the cracking stock mixture after described heating and olefin;
(2) before described cleavage reaction product is injected described quenching apparatus, described cleavage reaction product and olefins contact are reacted.
In the present invention, liquid cracking stock enters separately the process that described convection zone 10 carries out heat exchange and is called warm, and water vapour and liquid cracking stock mix (also i.e. cracking stock mixture) enters the process that described convection zone 10 carries out heat exchange and be called heat-processed.
In described method of the present invention, process (1) adds alkene in the ingress of radiation section 9, and process (2) adds alkene in the exit of radiation section 9.And in the present invention, described alkene is before addition without convection zone 10 or other heating means preheats.
In a preferred embodiment, described steam cracking method also comprises: before being mixed with water vapour by described liquid cracking stock, described liquid cracking stock is carried out preheating in described convection zone 10.According to this embodiment, by making liquid cracking stock carry out preheating in advance before mixing with water vapour, the object alleviating coking 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 the present invention, when described steam cracking method comprises process (1), be preferably provided with raw material preheating section 11, dilution steam generation superheat section 13 and mixing preheating section 15 in described convection zone 10, described steam cracking method preferably includes:
(1) by the preheating in described raw material preheating section 11 of liquid cracking stock;
(2) by water vapour preheating in described dilution steam generation superheat section 13;
(3) the liquid cracking stock through preheating step (1) obtained mixes with the water vapour through preheating that step (2) obtains, and the cracking stock mixture obtained is heated in described mixing preheating section 15, make described cracking stock mixture vaporize and be heated to cross-over temperature;
(4) the cracking stock mixture of vaporization step (3) obtained and olefin, and the mixture obtained is added to radiation section 9 and carries out scission reaction;
(5) cleavage reaction product that step (4) obtains is injected described quenching apparatus 7 and carry out refrigerated separation.
In the above-described embodiment, step (1) and step (2) do not have the priority working order of considered critical, and preferably, step (1) and step (2) are synchronously carried out.
In the present invention, when described steam cracking method comprises process (2), be preferably provided with raw material preheating section 11, dilution steam generation superheat section 13 and mixing preheating section 15 in described convection zone 10, described steam cracking method preferably includes:
(1) by the preheating in described raw material preheating section 11 of liquid cracking stock;
(2) by water vapour preheating in described dilution steam generation superheat section 13;
(3) the liquid cracking stock through preheating step (1) obtained mixes with the water vapour through preheating that step (2) obtains, and the cracking stock mixture obtained is heated in described mixing preheating section 15, make described cracking stock mixture vaporize and be heated to cross-over temperature;
(4) the cracking stock mixture of vaporization step (3) obtained is added to radiation section 9 and carries out scission reaction;
(5) cleavage reaction product step (4) obtained and olefins contact react, and then the product obtained after reaction are injected described quenching apparatus 7 and carry out refrigerated separation.
In the above-described embodiment, step (1) and step (2) do not have the priority working order of considered critical, and preferably, step (1) and step (2) are synchronously carried out.
In more preferably embodiment, described steam cracking method comprises process (1) and (2) simultaneously, now, be preferably provided with raw material preheating section 11, dilution steam generation superheat section 13 and mixing preheating section 15 in described convection zone 10, described steam cracking method preferably includes:
(1) by the preheating in described raw material preheating section 11 of liquid cracking stock;
(2) by water vapour preheating in described dilution steam generation superheat section 13;
(3) the liquid cracking stock through preheating step (1) obtained mixes with the water vapour through preheating that step (2) obtains, and the cracking stock mixture obtained is heated in described mixing preheating section 15, make described cracking stock mixture vaporize and be heated to cross-over temperature;
(4) the cracking stock mixture of vaporization step (3) obtained and olefin, and the mixture obtained is added to radiation section 9 and carries out scission reaction;
(5) cleavage reaction product step (4) obtained and olefins contact react, and then the product obtained after reaction are injected described quenching apparatus 7 and carry out refrigerated separation.
In above-mentioned more preferably embodiment, step (1) and step (2) do not have the priority working order of considered critical, and preferably, step (1) and step (2) are synchronously carried out.
For above-mentioned more preferably embodiment, particularly, as shown in Figure 2, in described convection zone 10, liquid cracking stock 1 is carried out preheating through raw material preheating section 11, 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 water vapour 3 through the preheating of described dilution steam generation superheat section 13, obtain cracking stock mixture; Then described cracking stock mixture is heated through Hybrid Heating section 15, to be heated to cross-over temperature by cracking stock mixture, then with one olefin, and the mixture obtained injection radiation section 9 is carried out scission reaction; Then, the cleavage reaction product obtained and another strand of olefins contact are reacted, then the reaction product obtained is injected described quenching apparatus 7 and carry out refrigerated separation.
In addition, in the above-described embodiment, 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 case, 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 the process mixed with water vapour by liquid cracking stock, 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 process (1), the weight ratio of the consumption of described alkene and described liquid cracking stock can be 0.001-0.5:1, is preferably 0.01-0.2:1.
In process (2), the weight ratio of the consumption of described alkene and described liquid cracking stock can be 0.001-0.5:1, is preferably 0.01-0.2:1.
In described method provided by the invention, the scission reaction in described radiation section 9 is substantially identical with the scission reaction occurred in the radiation section 9 of pyrolyzer in conventional steam cracking method, and therefore, described scission reaction can be implemented by crack reacting condition conveniently.In the preferred case, the condition of described 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; Reaction times (also namely entering the residence time of reaction mass in described radiation section 9 in radiation section 9) is 0.1-0.5 second, is preferably 0.2-0.3 second.
In process (2), the time that described cleavage reaction product reacts with olefins contact is shorter, can be less than 0.1 second, is preferably 0.001-0.05 second.The described catalytic time refer to from the cleavage reaction product of radiation section 9 and the mixture of alkene enter described quenching apparatus 7 the former two mix duration of contact.
In described method provided by the invention, in process (1) and process (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, process (1) is identical with the described alkene of process (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 process (1) and process (2) comprises 1-butylene and/or the 2-butylene of above-mentioned content, method according to the present invention can significantly improve the yield of divinyl.
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.
Convection zone pyrolyzer is as shown in Figure 2 adopted to carry out scission reaction.Detailed process comprises:
By as shown in table 1 for the petroleum naphtha 1(correlation parameter of 60 DEG C) carry out preheating through raw material preheating section 11; Water vapour 3 is carried out preheating through dilution steam generation superheat section 13 simultaneously; Then the petroleum naphtha through preheating is mixed with the water vapour through preheating, and the cracking stock mixture obtained is heated to cross-over temperature through Hybrid Heating section 15, then form as shown in table 2 with first gang of hybrid C 4 alkene 16() mix, and the mixture obtained injection radiation section 9 is carried out scission reaction; Then the cleavage reaction product obtained and second gang of hybrid C 4 alkene 16(being formed as shown in table 2) hybrid concurrency is raw reacts, afterwards the product be obtained by reacting is injected rapid-cooling heat exchanger 7 and carry 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, the injection rate of water vapour is 22700kg/h, the charging capacity of first strand of hybrid C 4 alkene is 2270kg/h, the injection rate of second strand of hybrid C 4 alkene 16 is 1362kg/h, (XOT) is 590 DEG C cross-over temperature, and 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 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, difference is, as shown in Figure 1, does not inject described hybrid C 4 alkene 16 in the ingress of radiation section 9, do not inject described hybrid C 4 alkene 16 in the exit of radiation section 9, and the charging capacity of petroleum naphtha is 45400kg/h.Wherein, the processing parameter of convection zone is as shown in table 5, and 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 alkene in the ingress of radiation section 9 and exit as part cracking stock in embodiment 1.
And, as can be seen from the data of table 3 and table 5, although the pressure drop of rapid-cooling heat exchanger 7 between end-of-run outlet with entrance has a little increase relative to comparative example 1 (embodiment 1 is 24.9kPa/g in embodiment 1, comparative example 1 is 23.8kPa/g), but the temperature out of rapid-cooling heat exchanger 7 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 in the exit of radiation section 9 and ingress, not only can not cause blocking owing to producing serious coking in the convection zone 10 of pyrolyzer and rapid-cooling heat exchanger 7, but also achieve effective utilization of the heat to the high-temperature split product from radiation section 9, 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, difference is, described hybrid C 4 alkene is not added in the ingress of described radiation section 9, wherein, the charging capacity of petroleum naphtha is 45400kg/h, and the injection rate of water vapour is 22700kg/h, the injection rate of second strand of hybrid C 4 alkene 16 is 1362kg/h, (XOT) is 590 DEG C cross-over temperature, and the temperature out (COT) of the radiation section of pyrolyzer is 830 DEG C, and the scission reaction time in radiation section 9 is 0.3 second.Other processing parameters of convection zone 10 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 | 0.83 |
| Methane | 11.75 |
| Ethane | 3.22 |
| Ethene | 28.69 |
| Acetylene | 0.33 |
| Propane | 0.46 |
| Propylene | 16.93 |
| Propine | 0.30 |
| Propadiene | 0.23 |
| Trimethylmethane | 0.03 |
| Normal butane | 0.35 |
| Butene-1 | 2.29 |
| Iso-butylene | 2.88 |
| Anti-butylene | 1.24 |
| Maleic | 1.42 |
| Divinyl | 5.22 |
| Other | 23.83 |
| 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, described hybrid C 4 alkene is not added in the exit of described radiation section 9, wherein, the charging capacity of petroleum naphtha is 43130kg/h, and the injection rate of water vapour is 22700kg/h, the amount of the described hybrid C 4 alkene of the exit injection of described radiation section 9 is 2270kg/h, (XOT) is 590 DEG C cross-over temperature, and 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 convection zone 10 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 | 0.87 |
| Methane | 11.68 |
| Ethane | 3.23 |
| Ethene | 28.27 |
| Acetylene | 0.32 |
| Propane | 0.48 |
| Propylene | 16.90 |
| Propine | 0.31 |
| Propadiene | 0.23 |
| Trimethylmethane | 0.03 |
| Normal butane | 0.35 |
| Butene-1 | 2.11 |
| Iso-butylene | 2.79 |
| Anti-butylene | 1.04 |
| Maleic | 1.41 |
| Divinyl | 5.53 |
| Other | 24.45 |
| Add up to | 100.00 |
By table 3,7 and 9 being compared and table 4,8 and 10 being compared and can find out, according to described method provided by the invention, by all introducing alkene as part cracking stock in the ingress of radiation section 9 and exit, effectively can not only utilize the heat of the high-temperature split product from radiation section 9, but also significantly improve butadiene yield.
Claims (12)
1. a 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: mixed with water vapour by liquid cracking stock, and the cracking stock mixture obtained is heated to cross-over temperature in described convection zone, cracking stock mixture after heating is added to radiation section and carries out scission reaction, then the cleavage reaction product obtained is injected described quenching apparatus and carry out refrigerated separation, it is characterized in that, described method also comprises following process:
Before the cracking stock mixture after described heating is added to radiation section, by the cracking stock mixture after described heating and olefin;
Wherein, described alkene contains 1-butylene and/or the 2-butylene of more than 10 % by weight.
2. method according to claim 1, wherein, described method also comprises: before being mixed with water vapour by described liquid cracking stock, 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. method according to claim 1, wherein, in the process mixed with water vapour by liquid cracking stock, the weight ratio of the consumption of described liquid cracking stock and water vapour is 1-4:1.
6. method according to claim 5, wherein, in the process mixed with water vapour by liquid cracking stock, the weight ratio of the consumption of described liquid cracking stock and water vapour is 1.5-2.5:1.
7. method according to claim 1 or 5, wherein, the weight ratio of the consumption of described alkene and described liquid cracking stock is 0.001-0.5:1.
8. method according to claim 7, wherein, the weight ratio of the consumption of described alkene and described liquid cracking stock is 0.01-0.2:1.
9. the method according to any one in claim 1-6 and 8, wherein, the condition of described scission reaction comprises: described is 560-660 DEG C cross-over temperature, and the temperature out of described radiation section is 780-850 DEG C, and the reaction times is 0.1-0.5 second.
10. method according to claim 9, wherein, the condition of described scission reaction comprises: described is 580-640 DEG C cross-over temperature, and the temperature out of described radiation section is 790-840 DEG C, and the reaction times is 0.2-0.3 second.
11. methods according to any one in claim 1-6,8 and 10, wherein, described alkene contains 1-butylene and/or the 2-butylene of more than 50 % by weight.
12. methods according to any one in claim 1-6,8 and 10, wherein, described liquid cracking stock is petroleum naphtha and/or hydrogenation tail oil.
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