CN103788991A - Steam cracking method - Google Patents
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- CN103788991A CN103788991A CN201210420746.9A CN201210420746A CN103788991A CN 103788991 A CN103788991 A CN 103788991A CN 201210420746 A CN201210420746 A CN 201210420746A CN 103788991 A CN103788991 A CN 103788991A
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Abstract
A steam cracking method comprises the following steps: mixing a liquid cracking raw material with water steam, heating the above obtained cracking raw material mixture in a convection section to an across temperature, adding the heated cracking raw material mixture into a radiant section, carrying out a cracking reaction, injecting the above obtained cracking reaction product into a quenching apparatus, and cooling and separating, wherein the method also comprises a step that a material flow containing olefin is added at the inlet and/or outlet of the radiant section, and the material flow containing olefin is a mixture containing heated olefin and hydrogen, or a mixture containing the heated olefin, hydrogen and the water steam. The method allows olefin to be introduced at the outlet and/or inlet of the radiant section, so coking generated in the convection section of a cracking furnace and in the quenching apparatus does not appear, the effective utilization of heat of high temperature cracking products from the radiant section can be realized, and the butadiene yield is improved.
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.The method of at present, producing low-carbon alkene is take tube furnace cracking petroleum hydrocarbon vapor technique as main.According to statistics, in the world divinyl more than about 99% ethene, more than 50% propylene and 90% by this explained hereafter.
The production equipment of being set up for core technology with the deep cooling process for separating in steam cracking in pipe type cracking furnace technique and downstream thereof is called ethylene unit.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, and the two mixing the post-heating that gasifies, to initial cracking temperature (i.e. " cross-over temperature "), then enter radiant coil cracking.In industrial pyrolysis furnace radiation section, the some groups of boiler tubes that configuration is identical of conventionally having arranged.In boiler tube, pass into cracking stock, the outer employing of boiler tube heated tube wall by liquid fuel or gas fuel combustion institute liberated heat, and by the heat transfer of tube wall, transfers heat to the cracking stock in boiler tube.
As everyone knows, cracking refers to that bubble point oil hydrocarbon is under hot 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 main, the simultaneously alkene such as by-product butylene, divinyl and pyrolysis gasoline, diesel oil, fuel wet goods product.
In recent years, the synthetic rubber take divinyl as monomer and synthetic resins fast development, 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 divinyl yield of different cracking stocks is also not quite similar, and for gas cracking stock (low-carbon alkanes below C5), the yield of divinyl is lower, such as the yield of divinyl in the cracking product of normal butane is only in 4% left and right; For liquid cracking stock (as petroleum naphtha, hydrogenation tail oil etc.), divinyl yield is relatively high, such as the yield of divinyl in the cracking product of hydrogenation tail oil is up to 7%.It has been generally acknowledged that for those can not be as for the alkene of cracking stock, the divinyl yield of some alkene is quite high, such as, the divinyl yield of maleic can shockingly reach 18%, if therefore wishing increases divinyl output, alkene as being added to pyrolyzer, maleic can be carried out to scission reaction.
Typically, the cracking section of ethylene unit is made up of some liquid pyrolyzer 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 in the time of charging is gas phase, vaporizes without the convection zone at pyrolyzer, and the convection zone design of pyrolyzer is often relatively simple; The raw material of liquid pyrolyzer is generally petroleum naphtha, diesel oil and hydrogenation tail oil etc., and the phase during due to these cracking stock chargings is liquid phase, need to vaporize at the convection zone of pyrolyzer, and the design of the convection zone of this pyrolyzer is often relatively more complex.If wish to increase the yield of divinyl in normal situation, just must consider the cracking of unsaturated hydrocarbons in liquid starting material pyrolyzer, the quantity that reason is gas pyrolyzer is very little.
Generally speaking, the effect of the convection zone of pyrolyzer mainly contains two, and the one, by cracking stock preheating, vaporize and be superheated to initial cracking temperature (cross-over temperature), the 2nd, the waste heat in recovered flue gas, to improve the thermo-efficiency of stove.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 also development of convection zone technology of pyrolyzer, the one, the hop count of convection section in cracking furnace is more and more, 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; The 2nd, the injection mode variation of dilution steam generation, adopts different steam injection modes according to the difference of raw material, as steam injection and secondary steam injection.Adopting different steam injection modes is in order to prevent the coking of raw material at convection zone, for liquid starting materials such as petroleum naphtha, diesel oil and hydrogenation tail oils, in convection zone heat-processed, there is the process of vaporization in it, if there is alkene in raw material, 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.Once but serious coking appears in the convection zone of pyrolyzer, not only can have a strong impact on the heat transfer process of convection zone, and can cause that convection zone pressure drop increases suddenly, thereby the output of reduction pyrolyzer must be carried out mechanical decoking by pyrolyzer blowing out while reaching a certain limit.Therefore need to develop a kind of new steam cracking method, to adapt to the sneaking into operation under olefin component operating mode in raw material.
The convection zone that enters pyrolyzer for multiple different cracking stock, has proposed some embodiments in prior art.For example, CN1077978A has proposed a kind of convection zone and has adopted the method for the cracking petroleum hydrocarbon vapor ethene processed of twice steam injection, the method adopts 3 dispensing methods to inject the feeding manner of primary steam and some injection secondary steam, make pyrolyzer can adapt to lightweight material, also can adapt to heavy feed stock, and in the time that raw material switches, not need to change pipeline.The method of this patent application is only the change of steam injection mode, does not affect the final cracking yield of whole cracking technology and the quality of product.
CN1501898A has proposed the method for a kind of lightweight charging in the pyrolyzer cracking for the cracking of cracking heavy feedstocks, the method comprises to be sent into a part of lightweight charging in the feed entrance of convection section in cracking furnace, and other lightweight charging is sent into convection zone together with diluent gas.The method of this patent application has solved in the time that cracking stock is replaced by lightweight material by heavy feed stock, and how lightweight material enters the problem of pyrolyzer, and while making lightweight material by raw material preheating section, being unlikely to has excessive pressure drop.
US2009/0178956A1 has proposed a kind of for reducing the method for liquid cracking stock in convection zone coking, the method is that liquid starting material is equated to mode reduces its dividing potential drop by injected gas when the independent preheating, thereby improve liquid starting material with the mixed vaporization rate of dilution steam generation, thereby the formation of delays liquid raw material coking omen body, reduces and even eliminates 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 or eliminate the generation of coking in the time using heavy feed stock.But, in prior art, do not relate to using alkene as part cracking stock the method for injecting pyrolyzer and carry out steam cracking, more do not relate to and how to solve alkene and inject pyrolyzer and can occur the problem of coking as part cracking stock.
Conventionally, 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, thereby scission reaction occurs, generate micromolecular cracking target product, as ethene, propylene and divinyl etc.And at high temperature there is secondary reaction and generate non-target product in the splitting gas of the radiation section of pyrolyzer outlet, therefore, need to Pintsch process gas is cooling to avoid affecting the yield of target product owing to there is too much secondary reaction fast in the radiation section outlet of pyrolyzer.The chilling of splitting gas can adopt direct quench and indirect quench, and directly quench directly contacts cryogen with splitting gas exactly, makes splitting gas cooling rapidly; Quench is exactly indirectly to contact with splitting gas by wall with cryogen indirectly, makes splitting gas cooling 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, utilize transfer line exchanger (TLE) to carry out chilling and reclaim heat generation steam splitting gas.
Summary of the invention
To the object of the invention is the problem of injecting pyrolyzer meeting generation coking using alkene as part cracking stock in order overcoming, a kind of new steam cracking method to be provided.
The invention provides a kind of steam cracking method, the method is implemented in cracking apparatus, described cracking apparatus comprises pyrolyzer, quenching apparatus and heating unit, described pyrolyzer comprises convection zone and radiation section, described method comprises: liquid cracking stock is mixed with water vapour, and the cracking stock mixture obtaining 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 obtaining is injected to described quenching apparatus and carry out refrigerated separation, wherein, described method also comprises at least one in following two processes:
(1) alkene is heated in heating unit, and before the cracking stock mixture after described heating is added to radiation section, by the cracking stock mixture after described heating with mixes containing the logistics of alkene, the described logistics containing alkene be the mixture of alkene after heating and hydrogen or heat after alkene and the mixture of hydrogen and water vapour;
(2) alkene is heated in heating unit, and before described cleavage reaction product is injected to described quenching apparatus, by described cleavage reaction product with containing the logistics contact reacts of alkene, the alkene that the described logistics containing alkene is alkene after heating with the mixture of hydrogen or after heating and the mixture of hydrogen and water vapour.
In described steam cracking method provided by the invention, in process (1), alkene is to add in the ingress of radiation section, therefore can't cause occurring in the convection zone of pyrolyzer coking adding of alkene.And, in the radiation section of pyrolyzer, alkene can with liquid cracking stock generation copyrolysis, can obtain higher divinyl yield, particularly, in the time that alkene contains a certain amount of 1-butylene and/or 2-butylene, divinyl 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 to the radiation section exit of pyrolyzer, can in increasing cracking product, reduce the temperature of splitting gas, to reach the object of the high temperature heat that makes full use of splitting gas.But, if directly conventional liquid cracking stock is injected to the radiation section exit of pyrolyzer, because the cracking temperature in radiation section exit can significantly 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, thereby increase the coking rate of quenching apparatus, and then can affect the cycle of operation of whole cracking apparatus.
For this reason, in process (2), by alkene being injected to the radiation section exit of pyrolyzer, after mixing with the cleavage reaction product being produced by radiation section, alkene can there is scission reaction, the cracking temperature required due to alkene itself is lower, and after olefin cracking, can not produce liquid-phase pyrolysis product, therefore, process (2) in described steam cracking method of the present invention not only can effectively be utilized the heat of high temperature of the cleavage reaction product being produced by radiation section, increase cracking product, but also can slow down the coking of quenching apparatus; And, hydrogen add further slow down coking, particularly when alkene, hydrogen, to add the effect of fashionable slow down coking together with water vapour more obvious.
In addition, in step (2), by adding alkene in radiation section exit, can further there is copyrolysis with the split product from radiation section in alkene, produce divinyl, thereby can obtain higher divinyl yield, particularly, in the time that alkene contains a certain amount of 1-butylene and/or 2-butylene, divinyl yield can be significantly improved.
Other features and advantages of the present invention are described in detail the embodiment part subsequently.
Accompanying drawing explanation
Accompanying drawing is to be 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 of the prior art cracking apparatus that comprises pyrolyzer and quenching apparatus;
Fig. 2 is schematic diagram and the flow direction of material schematic diagram of the present invention's cracking apparatus of comprising 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 sections
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 elaborated.Should be understood that, embodiment described herein only, for description and interpretation the present invention, is not limited to the present invention.
In the present invention, in the situation that not doing contrary explanation, the noun of locality of use typically refers to reference to shown in the drawings upper and lower as " upper and lower "; " inside and outside " refers to inside and outside with respect to the profile of each parts itself.
Fig. 2 is schematic diagram and the flow direction of material schematic diagram that comprises the cracking apparatus of 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 being obtained by described cracking stock is further heated to scission reaction occurs after convection zone 10 preheatings.Split product injection rapid-cooling heat exchanger 7 carries out cooling, 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 and in later separation device, isolates the target product of wanting through splitting gas house steward 17.The high-temperature flue gas that the interior burning of radiation section 9 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 from the high-temperature flue gas of radiation section 9, the convection zone 10 of described pyrolyzer is provided with multiple sections for reclaiming heat conventionally.Conventionally, described convection zone 10 can be provided with one or more 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.Described raw material preheating section 11 is generally used for cracking stock to carry out preheating.Preheating is carried out in the oiler feed that described oiler feed preheating section 12 is generally used for being supplied in drum 6.Described dilution steam generation superheat section 13 is generally used for dilution steam generation (as water vapour) to carry out preheating.Described extra high pressure steam superheat section 14 is generally used for heating to obtain extra high pressure steam from the high pressure steam of drum 6.Described Hybrid Heating section 15 is generally used for cracking stock to be heated to cross-over temperature.For above mentioned these sections, can arrange according to actual needs, for example, in the time that described cracking stock need to first carry out preheating and mixes with other logistics (as dilution steam generation), need to arrange described raw material preheating section 11, on the contrary, 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 sections 11.In one embodiment, when described cracking stock injects by multiply logistics, and per share logistics is while all needing in advance mutually to mix through preheating again, multiple raw material preheating sections 11 are set described convection zone 10 is interior, each raw material preheating section 11 is carried out preheating to one logistics respectively.In another embodiment, when described cracking stock need to be preheated to higher temperature, and target temperature can not be preheated to through a raw material preheating section time, need to multiple raw material preheating sections 11 be set described convection zone 10 is interior, so that described cracking stock is carried out to repeatedly preheating.
According to needs of production, in order to obtain the extra high pressure steam of specified temp and pressure, can one or more extra high pressure steam superheat sections 14 be set described convection zone 10 is interior.
According to needs of production, in order cracking stock to be heated to cross-over temperature to alleviate the load of radiation section, can one or more Hybrid Heating sections be set described convection zone 10 is interior.
In described pyrolyzer, in the time being provided with the plural section being 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 need to carry out the heating of higher-strength, also while being heated to higher temperature, this section can be arranged on to the position across section 8 near described flue gas, 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 need to carry out more low intensive heating, while being also heated to lower temperature, this section can be arranged on to the position across section 8 away from described flue gas because from described flue gas across section 8 more away from the temperature of flue gas lower.For example, 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, quenching apparatus 7 and heating unit (not shown), described pyrolyzer comprises convection zone 10 and radiation section 9, described method comprises: liquid cracking stock is mixed with water vapour, and the cracking stock mixture obtaining 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 obtaining is injected to described quenching apparatus 7 and carry out refrigerated separation, wherein, described method also comprises at least one in following two processes:
(1) alkene is heated in heating unit, and before the cracking stock mixture after described heating is added to radiation section, by the cracking stock mixture after described heating with mixes containing the logistics of alkene, the described logistics containing alkene be the mixture of alkene after heating and hydrogen or heat after alkene and the mixture of hydrogen and water vapour;
(2) alkene is heated in heating unit, and before described cleavage reaction product is injected to described quenching apparatus, by described cleavage reaction product with containing the logistics contact reacts of alkene, the alkene that the described logistics containing alkene is alkene after heating with the mixture of hydrogen or after heating and the mixture of hydrogen and water vapour.
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 (being also cracking stock mixture) and enter 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) is that add the described logistics containing alkene, process (2) in the ingress of radiation section 9 be to add the described logistics containing alkene in the exit of radiation section 9.Described, containing in the logistics of alkene, described alkene heated through heating unit.
In described method of the present invention, in process (1) and process (2), the temperature of described alkene after described heating unit heating can be 120-250 ℃ separately, is preferably 150-200 ℃.Can for the heating unit of various routines, for example, can be vaporizer for the heating unit that heats described alkene.In the preferred case, described alkene is injected to vaporizer and vaporize, the alkene after vaporization is mixed with hydrogen, and optionally add water vapour, then the mixture obtaining is injected to ingress and/or the exit of described radiation section 9.
In the time that described steam cracking method of the present invention comprises process (1) and process (2) simultaneously, the alkene in process (1) and process (2) can heat in same heating unit.
In a kind of preferred implementation, described steam cracking method also comprises: before described liquid cracking stock is mixed with water vapour, described liquid cracking stock is carried out to preheating in described convection zone 10.According to this embodiment, by making liquid cracking stock carry out in advance preheating before mixing with water vapour, can reach the object that alleviates coking.Preferably, the temperature of described liquid cracking stock after described convection zone 10 preheatings is 120-300 ℃, more preferably 150-250 ℃.
In the present invention, in the time that described steam cracking method comprises process (1), described convection zone 10 is interior to be preferably provided with raw material preheating section 11, dilution steam generation superheat section 13 and to mix preheating section 15, and described steam cracking method preferably includes:
(1) by liquid cracking stock in the interior preheating of described raw material preheating section 11;
(2) by water vapour in the interior preheating of described dilution steam generation superheat section 13;
(3) water vapour through preheating that the liquid cracking stock through preheating step (1) being obtained obtains with step (2) mixes, and by the cracking stock mixture obtaining in the interior heating of described mixing preheating section 15, make described cracking stock mixture vaporize and be heated to cross-over temperature;
(4) alkene is heated in heating unit, the alkene after heating is mixed with hydrogen, and optionally add water vapour in the mixture obtaining, obtain the logistics containing alkene;
(5) what the cracking stock mixture of vaporization step (3) being obtained obtained with step (4) mixes containing the logistics of alkene, and the mixture obtaining is added to radiation section 9 carries out scission reaction;
(6) cleavage reaction product step (5) being obtained injects described quenching apparatus 7 and carries out refrigerated separation.
In the above-described embodiment, step (1), step (2) and step (4) do not have the strict priority working order limiting, and preferably, step (1), step (2) and step (4) are synchronously carried out.
In the present invention, in the time that described steam cracking method comprises process (2), described convection zone 10 is interior to be preferably provided with raw material preheating section 11, dilution steam generation superheat section 13 and to mix preheating section 15, and described steam cracking method preferably includes:
(1) by liquid cracking stock in the interior preheating of described raw material preheating section 11;
(2) by water vapour in the interior preheating of described dilution steam generation superheat section 13;
(3) water vapour through preheating that the liquid cracking stock through preheating step (1) being obtained obtains with step (2) mixes, and by the cracking stock mixture obtaining in the interior heating of 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) being obtained is added to radiation section 9 and carries out scission reaction;
(5) alkene is heated in heating unit, the alkene after heating is mixed with hydrogen, and optionally add water vapour in the mixture obtaining, obtain the logistics containing alkene;
(6) the logistics contact reacts containing alkene that cleavage reaction product step (4) being obtained and step (5) obtain, then injects described quenching apparatus 7 by the product obtaining after reaction and carries out refrigerated separation.
In the above-described embodiment, step (1), step (2) and step (5) do not have the strict priority working order limiting, and preferably, step (1), step (2) and step (5) are synchronously carried out.
In embodiment more preferably, described steam cracking method comprises process (1) and (2) simultaneously, now, described convection zone 10 is interior to be preferably provided with raw material preheating section 11, dilution steam generation superheat section 13 and to mix preheating section 15, and described steam cracking method preferably includes:
(1) by liquid cracking stock in the interior preheating of described raw material preheating section 11;
(2) by water vapour in the interior preheating of described dilution steam generation superheat section 13;
(3) water vapour through preheating that the liquid cracking stock through preheating step (1) being obtained obtains with step (2) mixes, and by the cracking stock mixture obtaining in the interior heating of described mixing preheating section 15, make described cracking stock mixture vaporize and be heated to cross-over temperature;
(4) alkene is heated in heating unit, the alkene after heating is mixed with hydrogen, and optionally add water vapour in the mixture obtaining, obtain the logistics containing alkene;
(5) what the cracking stock mixture of vaporization step (3) being obtained obtained with step (4) mixes containing the logistics of alkene, and the mixture obtaining is added to radiation section 9 carries out scission reaction;
(6) the logistics contact reacts containing alkene that cleavage reaction product step (5) being obtained and step (4) obtain, then injects described quenching apparatus 7 by the product obtaining after reaction and carries out refrigerated separation.
In above-mentioned more preferably embodiment, step (1), step (2) and (4) do not have the strict priority working order limiting, and preferably, synchronously carry out step (1), step (2) and (4).
For above-mentioned more preferably embodiment, particularly, as shown in Figure 2, in described convection zone 10, liquid cracking stock 1 is carried out to preheating through raw material preheating section 11, water vapour 3 is carried out to preheating through dilution steam generation superheat section 13 simultaneously, afterwards the liquid cracking stock through described raw material preheating section 11 preheatings is mixed with the water vapour 3 through described dilution steam generation superheat section 13 preheatings, 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 mix containing logistics of alkene (i.e. the mixture of the alkene after heating unit heating and the mixture of hydrogen or the alkene after heating unit heating and hydrogen and water vapour) with one, and the mixture injection radiation section 9 obtaining is carried out to scission reaction; Then, the cleavage reaction product obtaining and another strand, containing the logistics of alkene (i.e. alkene after heating unit heating and the mixture of hydrogen or the alkene after heating unit heats and the mixture of hydrogen and water vapour) contact reacts, are then injected the reaction product obtaining to 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, can optionally oiler feed 2 be heated by oiler feed preheating section 12, and the high pressure steam from drum 64 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 that liquid cracking stock is mixed with water vapour, 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 0.01-0.4:1; The weight ratio of the consumption of described alkene and hydrogen can be 50-1000:1, is preferably 80-800:1; The weight ratio of the consumption of water vapour and described alkene is 0-5:1, is preferably 0.1-3:1.
In process (2), the weight ratio of the consumption of described alkene and described liquid cracking stock can be 0.001-0.2:1, is preferably 0.01-0.1:1; The weight ratio of the consumption of described alkene and hydrogen can be 50-1000:1, is preferably 80-800:1; The weight ratio of the consumption of water vapour and described alkene is 0-5:1, is preferably 0.1-3:1.
In described method provided by the invention, the scission reaction occurring in the radiation section 9 of pyrolyzer in the scission reaction in described radiation section 9 and conventional steam cracking method is basic identical, and therefore, described scission reaction can be implemented according to conventional crack reacting condition.In the preferred case, the condition of described scission reaction comprises: described is 560-660 ℃ cross-over temperature, is preferably 580-640 ℃; The temperature out of described radiation section is 780-850 ℃, is preferably 790-840 ℃; Reaction times (also entering reaction mass in radiation section 9 residence time in described radiation section 9) is 0.1-0.5 second, is preferably 0.2-0.3 second.
In process (2), shorter from the cleavage reaction product of radiation section 9 and described catalytic time of logistics containing alkene, can be, below 0.1 second, to be preferably 0.001-0.05 second.Before the described catalytic time refers to and entering described quenching apparatus 7 from the cleavage reaction product of radiation section 9 with the mixture of the described logistics containing alkene adding in the exit of radiation section 9 (alkene of the alkene after heating with the mixture of hydrogen or after heating and the mixture of hydrogen and water vapour), the two mixes 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 routines separately, for example, 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 more than 10 % by weight 1-butylene and/or 2-butylene, more preferably all contains more than 50 % by weight 1-butylene and/or 2-butylene.Such alkene can be for example conventional hybrid C 4 alkene.When the 1-butylene that comprises above-mentioned content when the described alkene of process (1) and process (2) and/or 2-butylene, method according to the present invention can significantly improve the yield of divinyl.And, in the time that process (1) is identical with described alkene in process (2), the described logistics containing alkene of step (1) can be identical or different with the described logistics that contains alkene of step (2), is also that the proportioning of each component in the two and each component can be identical or different.
In described method provided by the invention, described liquid cracking stock can be the conventional various liquid cracking stocks that use in this area, for example, 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 used for illustrating described steam cracking method provided by the invention.
Adopt convection zone pyrolyzer as shown in Figure 2 to carry out scission reaction.Detailed process comprises:
By as shown in table 2 hybrid C 4 alkene 16(composition) add in vaporizer and vaporize, obtain temperature and be the hybrid C 4 alkene of 180 ℃, then this hybrid C 4 alkene is mixed with hydrogen 18 and water vapour 3, obtain containing the logistics of alkene.
By as shown in table 1 the petroleum naphtha 1(correlation parameter of 60 ℃) carry out preheating through raw material preheating section 11; Water vapour 3 is carried out to 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 obtaining is heated to cross-over temperature through Hybrid Heating section 15, then mix with first burst of logistics containing alkene, and the mixture obtaining is injected to radiation section 9 and carry out scission reaction; Then react raw to the cleavage reaction product obtaining and second strand of logistics hybrid concurrency containing alkene, the product afterwards reaction being obtained injects rapid-cooling heat exchanger 7 and carries out refrigerated separation, be separated into high pressure steam and splitting gas, splitting gas is entered to later separation device through splitting gas house steward 17.Wherein, the charging capacity of petroleum naphtha is 43130kg/h, and the amount of the water vapour injecting at convection zone 10 is 22700kg/h; At first strand, containing in the logistics of alkene, the injection rate of described hybrid C 4 alkene is 2270kg/h, and the injection rate of hydrogen is 25kg/h, and the injection rate of water vapour is 2270kg/h; Contain in the logistics of alkene at second strand, the injection rate of described hybrid C 4 alkene is 1362kg/h, the injection rate of hydrogen is 15kg/h, the injection rate of water vapour is 2270kg/h, (XOT) is 590 ℃ cross-over temperature, the temperature out (COT) of the radiation section of pyrolyzer is 830 ℃, 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 by dividing the analysis of variance to learn to splitting gas, the composition of splitting gas is as shown in table 4.
Table 1
Table 2
Table 3
Table 4
Comparative example 1
Carry out steam cracking according to the method for embodiment 1, difference is as shown in Figure 1, do not inject the logistics containing alkene, and the charging capacity of petroleum naphtha to be 45400kg/h in ingress and the exit of radiation section 9.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
Data by table 4 and table 6 can be found out, the divinyl yield of embodiment 1 is 5.96 % by weight, and the divinyl yield of comparative example 1 is 4.84 % by weight, in embodiment 1, add alkene to make divinyl yield improve 23.14% as part cracking stock by the ingress at radiation section 9 and exit.
And, data by table 3 and table 5 can be found out, although the pressure drop of rapid-cooling heat exchanger 7 between end-of-run outlet and entrance has a little to increase that (embodiment 1 is 24.9kPa/g with respect to comparative example 1 in embodiment 1, comparative example 1 is 23.8kPa/g), but the temperature out of rapid-cooling heat exchanger 7 all declines to some extent from initial stage to latter stage.
As can be seen here, according to described method provided by the invention, introduce alkene by the exit at radiation section 9 and ingress, not only can not cause convection zone 10 and the rapid-cooling heat exchanger 7 of pyrolyzer interior because the serious coking of generation is stopped up, but also realized effective utilization of the heat to the high-temperature split product from radiation section 9, improve divinyl yield.
The present embodiment is used for illustrating described steam cracking method provided by the invention.
Carry out steam cracking according to the method for embodiment 1, difference is, do not add the described logistics containing alkene in the ingress of described radiation section 9, wherein, the charging capacity of petroleum naphtha is 45400kg/h, the injection rate of the water vapour injecting at convection zone 10 is 27200kg/h, what add in the exit of radiation section 9 is described containing in the logistics of alkene, the injection rate of described hybrid C 4 alkene is 2270kg/h, the injection rate of hydrogen is 25kg/h, the injection rate of water vapour is 2270kg/h, (XOT) is 590 ℃ cross-over temperature, the temperature out (COT) of the radiation section of pyrolyzer is 830 ℃, 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 by dividing the analysis of variance to learn to splitting gas, the composition of splitting gas is as shown in table 8.
Table 7
Table 8
The present embodiment is used for illustrating described steam cracking method provided by the invention.
Carry out steam cracking according to the method for embodiment 1, difference is, do not add the described logistics containing alkene in the exit of described radiation section 9, wherein, the charging capacity of petroleum naphtha is 43130kg/h, the injection rate of the water vapour injecting at convection zone 10 is 22700kg/h, what add in the exit of radiation section 9 is described containing in the logistics of alkene, the injection rate of described hybrid C 4 alkene is 2270kg/h, the injection rate of hydrogen is 25kg/h, the injection rate of water vapour is 1362kg/h, (XOT) is 590 ℃ cross-over temperature, the temperature out (COT) of the radiation section of pyrolyzer is 830 ℃, the scission reaction time in radiation section 9 is 0.25 second.Other processing parameters of convection zone 10 and chilling heat-exchanger rig 7 are as shown in table 10, and by dividing the analysis of variance to learn to splitting gas, the composition of splitting gas is as shown in table 9.
Table 9
Table 10
By table 3,7 and 10 being compared and table 4,8 and 9 being compared and can be found out, according to described method provided by the invention, all introduce alkene as part cracking stock by the ingress at radiation section 9 and exit, the heat of the high-temperature split product of self radiation section 9 not only can be effectively used to, but also divinyl yield can be significantly improved.
Claims (10)
1. a steam cracking method, the method is implemented in cracking apparatus, described cracking apparatus comprises pyrolyzer, quenching apparatus and heating unit, described pyrolyzer comprises convection zone and radiation section, described method comprises: liquid cracking stock is mixed with water vapour, and the cracking stock mixture obtaining 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 obtaining is injected to described quenching apparatus and carry out refrigerated separation, it is characterized in that, described method also comprises at least one in following two processes:
(1) alkene is heated in heating unit, and before the cracking stock mixture after described heating is added to radiation section, by the cracking stock mixture after described heating with mixes containing the logistics of alkene, the described logistics containing alkene be the mixture of alkene after heating and hydrogen or heat after alkene and the mixture of hydrogen and water vapour;
(2) alkene is heated in heating unit, and before described cleavage reaction product is injected to described quenching apparatus, by described cleavage reaction product with containing the logistics contact reacts of alkene, the alkene that the described logistics containing alkene is alkene after heating with the mixture of hydrogen or after heating and the mixture of hydrogen and water vapour.
2. method according to claim 1, wherein, described method also comprises: before described liquid cracking stock is mixed with water vapour, described liquid cracking stock is carried out to 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 ℃, is preferably 150-250 ℃.
4. method according to claim 1, wherein, in process (1) and process (2), the temperature of described alkene after the heating of the described heating unit 120-250 ℃ that respectively does for oneself, is preferably 150-200 ℃.
5. method according to claim 1, wherein, in the process that liquid cracking stock is mixed with water vapour, the weight ratio of the consumption of described liquid cracking stock and water vapour is 1-4:1, is preferably 1.5-2.5:1.
6. method according to claim 1 or 5, wherein, in process (1), the weight ratio of the consumption of described alkene and described liquid cracking stock is 0.001-0.5:1, is preferably 0.01-0.4:1; The weight ratio of the consumption of described alkene and hydrogen is 50-1000:1, is preferably 80-800:1; The weight ratio of the consumption of water vapour and described alkene is 0-5:1, is preferably 0.1-3:1.
7. method according to claim 1 or 5, wherein, in process (2), the weight ratio of the consumption of described alkene and described liquid cracking stock is 0.001-0.2:1, is preferably 0.01-0.1:1; The weight ratio of the consumption of described alkene and hydrogen is 50-1000:1, is preferably 80-800:1; The weight ratio of the consumption of water vapour and described alkene is 0-5:1, is preferably 0.1-3:1.
8. according to the method described in any one in claim 1-7, wherein, the condition of described scission reaction comprises: described is 560-660 ℃ cross-over temperature, is preferably 580-640 ℃; The temperature out of described radiation section is 780-850 ℃, is preferably 790-840 ℃; Reaction times is 0.1-0.5 second, is preferably 0.2-0.3 second.
9. according to the method described in any one in claim 1-8, wherein, in process (1) and process (2), described alkene contains 1-butylene and/or 2-butylene more than 10 % by weight, preferably contains more than 50 % by weight 1-butylene and/or 2-butylene.
10. according to the method described in any one in claim 1-8, wherein, described liquid cracking stock is petroleum naphtha and/or hydrogenation tail oil.
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| CN201210420746.9A CN103788991B (en) | 2012-10-29 | 2012-10-29 | A kind of steam cracking method |
| US14/064,244 US9505677B2 (en) | 2012-10-29 | 2013-10-28 | Steam cracking processes |
| RU2013147897A RU2640592C2 (en) | 2012-10-29 | 2013-10-28 | Steam cracking process |
| SG2013080239A SG2013080239A (en) | 2012-10-29 | 2013-10-28 | Steam cracking process |
| NL2011692A NL2011692C2 (en) | 2012-10-29 | 2013-10-29 | Steam cracking process. |
| BE2013/0734A BE1022626B1 (en) | 2012-10-29 | 2013-10-29 | STEAM CRACKAGE PROCESS |
| KR1020130129447A KR102159139B1 (en) | 2012-10-29 | 2013-10-29 | Steam cracking process |
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| GB571736A (en) * | 1942-09-15 | 1945-09-06 | Shell Dev | Dehydrogenation of butenes to butadiene |
| CN1050893A (en) * | 1989-10-13 | 1991-04-24 | 凯洛格总公司 | Steam cracking feed gas saturated |
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| GB571736A (en) * | 1942-09-15 | 1945-09-06 | Shell Dev | Dehydrogenation of butenes to butadiene |
| CN1050893A (en) * | 1989-10-13 | 1991-04-24 | 凯洛格总公司 | Steam cracking feed gas saturated |
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| 张利军: ""裂解反应模型的建立与应用研究"", 《中国博士学位论文全文数据库 工程科技I辑》, no. 05, 15 May 2012 (2012-05-15), pages 015 - 2 * |
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| CN105541535A (en) * | 2014-10-28 | 2016-05-04 | 中国石油化工股份有限公司 | Steam cracking method |
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