CN1152946C - Olefin plant recovery system employing catalytic distillation - Google Patents
Olefin plant recovery system employing catalytic distillation Download PDFInfo
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- CN1152946C CN1152946C CNB971817693A CN97181769A CN1152946C CN 1152946 C CN1152946 C CN 1152946C CN B971817693 A CNB971817693 A CN B971817693A CN 97181769 A CN97181769 A CN 97181769A CN 1152946 C CN1152946 C CN 1152946C
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Abstract
The present invention relates to an olefin device recovery system by means of catalytic distillation, which is characterized in that C2 to C5 and heavier alkyne and diolefin in cracked charging flows are hydrogenated and C2 olefin and C3 olefin are not obviously hydrogenated; in addition, C4 and heavier olefin can be hydrogenated. More specifically, cracked gas in an olefin device is charged and hydrogenated in a distillation reaction tower with hydrogenation catalysts, hydrogen does not need separating from the charged cracked gas, and the ethene and the propylene can not be obviously hydrogenated. A combined reaction and rectification step known as catalytic distillation hydrogenation is used to carry out a reaction process and a separation process at the same time, and on the other hand, hydrogenation reaction conditions are kept so that the ethene and the propylene are actually not hydrogenated and all other C2 unsaturated hydrocarbons or heavier unsaturated hydrocarbons are basically hydrogenated. Any hydrogen which does not react can be separated by a membrane and then makes a reaction with separated C9 and heavier ingredients to produce hydrocracked gasoline.
Description
Background of invention
The present invention relates to a kind of production method of alkene, especially relate to the charging of processing splitting gas, so that more effectively reclaim product and processed side product.
Ethene, propylene and other valuable petrochemical materials are to produce by the thermo-cracking of miscellaneous hydrocarbon raw material of decompression solar oil from ethane to the heavy.In the thermal cracking processes of these raw materials, the various products from hydrogen to the Pyrolysis fuel oil PFO have been produced.The effluent that is commonly called unstripped gas or splitting gas that is obtained by cleavage step is made up of the component of this entire area, they must be separated (rectifying) subsequently and become various products and by product, and then make the undersaturated byproduct reaction of at least a portion (hydrogenation).
Typical splitting gas also contains C except needed product ethene and propylene
2Alkynes, C
3Alkynes and diolefine, C
4Heavier alkynes, diolefine and alkene, and a considerable amount of hydrogen.In the most prior art method, C
2Alkynes, C
3Alkynes and diolefine, and C
5Heavier diolefine, alkynes and alkene are to carry out shortening with a series of catalyzer that can buy in fixed-bed reactor on market.In the application that day by day increases, C
4Alkynes, diolefine and alkene also in fixed-bed reactor by shortening.These independently hydrogenation step by a kind of the carrying out in two kinds of processing sequences.In first kind of processing sequence, splitting gas is compressed to 2.76-4.14MPa (400-600psia).Little by little with its deep cooling, make C then
2Heavier components condense.Hydrogen low temperature is reclaimed, and methane rectifying separation from logistics is gone out.Remaining C
2Heavier logistics enters a series of rectifying tower.First tower produces one and contains C
2Alkynes, the cat head fraction of alkene and alkane.This logistics is admitted to a Fixed Bed Gas Phase reactor, utilizes the previous hydrogen that low ternperature separation process obtains from splitting gas to make C there
2Alkynes generation selective hydrogenation.
Second tower in this order produces one and contains C
3Alkynes, diolefine, the overhead product of alkene and alkane.This logistics is admitted to a Fixed Bed Gas Phase or Liquid-phase reactor, utilizes the previous hydrogen that low ternperature separation process obtains from splitting gas to make C there
3Alkynes and diolefine generation selective hydrogenation.
The 3rd tower in this order produces one and contains C
4Alkynes, diolefine, the overhead product of alkene and paraffinic hydrocarbons.This logistics or be sent to the battery limit (BL) as a kind of the finished product, perhaps be sent to a fixed bed Liquid-phase reactor, utilize the previous hydrogen that the low temperature recovery obtains from splitting gas to make diolefine there, alkynes, and make alkene generation hydrogenation reaction in some cases.
The bottom product of the 3rd tower contains C
5Heavier diolefine, alkynes, alkene and paraffinic hydrocarbons.This logistics is sent in placed in-line two fixed bed Liquid-phase reactor.In first reactor, alkynes and diolefine are by shortening.In second reactor, alkene is by shortening.Two reactors all utilize the previous hydrogen that the low temperature recovery obtains from splitting gas.In some applications, the 3rd one of tower generation contains C
4And C
5Alkynes, diolefine, the overhead product of alkene and paraffinic hydrocarbons.As the front to only containing C
4It is the same that component is discussed, and makes its hydrogenation in an independent fixed bed Liquid-phase reactor.At the bottom of the tower of the 3rd tower, discharge C
6Heavier diolefine, alkynes, alkene and paraffinic hydrocarbons make their hydrogenation as previously mentioned in two fixed bed Liquid-phase reactor.
In second kind of processing sequence, splitting gas is compressed to 2.07-3.45MPa (300-50psia), and is sent in the rectifying tower.The overhead product of this tower is C in the splitting gas
3Lighter part.It is delivered in a series of Fixed Bed Gas Phase reactor, utilize C there
3Sub-fraction (generally less than 10%) hydrogen contained in the lighter logistics makes C
2Alkynes and a part of C
3Alkynes and diolefine generation hydrogenation.Not by that part of C of hydrogenation
3Alkynes and diolefine, and C
4Heavier alkynes, diolefine and alkene by a kind of and front to first kind of described similar mode of processing sequence by hydrogenation.This hydrogen that has still stayed above 90% need be reclaimed by low temperature.
Also must be before the hydrogenation reaction step, in this external this system with C
4Heavier component rectifying separation is come out.Otherwise hydrogenation reaction heat is excessive, and makes the very fast fouling of hydrogenation catalyst.Because this rectifying is to take place in the environment of high hydrogen and methane, so energy requirement is very high.
In most prior art, C
2And C
3Alkynes, and C
3Diolefine in hydrogen separation/recovery step with back end hydrogenation.C
4Heavier alkynes, the hydrogenation reaction of diolefine and alkene then always takes place later at the hydrogen separating step, and will consume available hydrogen total amount up to 80%.This hydrogenation reaction also is to utilize according to selectivity and the selected catalyzer of the desired hydrogen saturation ratio of specific method, takes place in fixed bed catalytic reactor.
Though above-described two kinds of processing sequences are widely adopted, and many shortcomings are also arranged.At first, splitting gas must have under the situation of hydrogen by deep cooling and condensation.Because the dividing potential drop of hydrogen is very high, for making C
2The required mechanical refrigeration of heavier components condense requires very high, has therefore increased the energy expenditure and the initial cost of this technology.In addition, also must be with the hydrogen low ternperature separation process, so that for various downstream reactors provide hydrogen, the demand in energy and investment all is very high like this.Moreover hydrogenation step takes place in a series of fixed-bed reactor, needs the independent reactor assembly of 3-6 platform, thereby has increased the complicacy of construction investment and device.
In United States Patent (USP) 3,692,864; 4,020,119; 4,404,124; The hydrogenation technique and the characteristics of various prior aries have been introduced in 4,443,559 and 4,973,790.In addition, in published International Patent Application WO 95/15934, disclosed a kind of selection catalytic hydrogenation method.
Summary of the invention
An object of the present invention is in the liquid phase of a boiling point reactors, to make the C in the feed stream
2-C
5And alkynes that may be heavier and diene hydrogenation, but do not make the C in the feed stream
2And C
3Hydrogenation of olefins.Can make C in addition
4, C
5And part or all of heavier hydrogenation of olefins, but do not make C
2And C
3Hydrogenation of olefins.
More precisely, an object of the present invention is to provide and a kind ofly from splitting gas, isolating the system and method that hydrogen and methane made the splitting gas hydrogenation in the olefin hydrocarbon apparatus in the past, thereby make by product, C
2Alkynes, C
3Alkynes and diolefine, C
4Heavier alkynes and diolefine, and also make C if necessary
4Heavier hydrogenation of olefins does not but make ethene and propylene that significant hydrogenation takes place.This is included in C
2The upstream of the deep cooling of heavy constituent and condensation operation more, utilize a reaction rectification step that is called as the combination of catalytic distillation hydrogenation to react simultaneously and separate, make the hydrogenation of required major product be prevented or reduce to minimum level, though consumed hydrogen, do not needed to carry out expensive hydrogen and separate.
C
4Heavier alkynes, the hydrogenation of diolefine and alkene make the removal of hydrogen be increased to 70-100%, and that the most general is 90-95%.The height of hydrogen is removed and has been reduced the dividing potential drop of hydrogen, thereby has reduced to making C
2The more required mechanical refrigeration demand of heavy constituent deep cooling and condensation has been saved energy and facility investment thus.The step of low ternperature separation process hydrogen is cancelled from splitting gas.Because all hydrogenation reactions all occur in the upstream of hydrogen-methane separation step, the required hydrogen of hydrogenation reaction is Already in the splitting gas.The low ternperature separation process step of cancellation hydrogen makes energy obtain saving, and facility investment reduces, and the complexity of technology is also alleviated.In the alternative method of another kind, can utilize the present invention to make alkynes and diene hydrogenation, the remarkable hydrogenation of alkene does not but take place.
In currently used two kinds of processing sequences, because the existence of alkynes and diolefine generally fouling can take place at the bottom of the rectifying Tata.For the tendency that makes fouling is reduced to the tower still service temperature that minimum need limit these towers, but must provide optional equipment usually with the assurance device operating continuity.The hydrogenation that carried out diolefine and alkynes before rectifying tower has just been eliminated the possibility in rectifying tower still generation fouling.
The accompanying drawing summary
Fig. 1 is the schema of traditional prior art olefin hydrocarbon apparatus.
Fig. 2 is the schema according to the part of olefin hydrocarbon apparatus of the present invention.
Fig. 3 is the schema according to the rest part of olefin hydrocarbon apparatus of the present invention, contains the downstream course of processing of the alkene of steam in order to explanation.
Fig. 4 is the schema similar with Fig. 2, but explanation is another kind of alternate embodiment of the present invention.
The narration of preferred embodiment
At first please referring to describing a traditional prior art olefin hydrocarbon apparatus, Fig. 1 of first kind of processing sequence being discussed in the preamble for example, compressed gas 10 is compressed to earlier the pressure of 2.76-4.14MPa (400-600psia) in 12.In 14, most of pressurized gas is carried out sub-zero treatment then, isolate hydrogen, then in 16, carry out methane separation.Sub-fraction C
3The condensation in compressor train of heavier component usually from low temperature demethanizing and the bypass of deethanizing step, and directly enters depropanizing tower as logistics 31.In 20, make air-flow 18 deethanizings subsequently, make C
2Air-flow is hydrogenation in 22, and rectifying in 24, has in fact produced ethene 26 and ethane 28.Still liquid depropanizing in 30 of deethanizing column 20 makes separated C
3Logistics 32 hydrogenation in 34, and rectifying in 36 have in fact produced propylene 38 and propane 40.Similarly, tower still product debutylize in 42 of depropanizing tower 30 makes C
4Logistics is hydrogenation in 44, C
5 +Logistics is hydrogenation in 46 then.Just as can be seen, almost whole feed stream all will pass through sub-zero treatment, and will carry out hydrogen before all hydrogenation and rectification step and separate.The hydrogen of separating is used in hydrogenation unit 22,24 subsequently in the downstream, in 44 and 46.This have sub-zero treatment and the isolating flow process of hydrogen to have the shortcoming that discussed the front.
Fig. 2 illustrates the present invention, and wherein splitting gas 50 is compressed in 52, but only is compressed to 0.69-1.72MPa (100-250psia), the preferably pressure of 1.21MPa (175psia).Compressed splitting gas is fed in the intake zone 54 of a catalytic distillation tower 56.This catalytic distillation tower is one and carries out catalyzed reaction and distillatory equipment simultaneously that it comprises a stripping section 58 and the rectifying/conversion zone 60 on intake zone 54 below intake zone 54.The distillation inner member of required any kind of is housed, for example the traditional tower tray 62 shown in Fig. 2 in the stripping section 58.Reboiler 63 turns back in the tower heated tower bottoms.
Rectifying/the conversion zone 60 of tower 56 has component reaction selected in the charging of making (hydrogenation) and makes the dual-use function of these component distillations.Therefore this section comprises a kind of bed 64 of traditional hydrogenation catalyst.To the requirement of this rectifying/conversion zone is to set up necessary condition, makes the unsaturated hydro carbons except that ethene and propylene can be by hydrogenation, and carries out the rectifying of necessity, with all basically C
4Lighter component is as the cat head fraction, and all basically C
6Heavier component as tower at the bottom of fraction separated.Part C
5Component, 10-90% is generally 70% C
5Component is left this tower as the cat head fraction, and rest part, is generally 30% C
5Component is then left this tower as fraction at the bottom of the tower.According to the technology of each device, raw material is different with the byproduct requirement, all C in some cases
5All will leave this tower as the cat head fraction.For can be to C
2Alkynes, C
3Alkynes and diolefine, and C
4Heavier alkynes, diolefine and alkene carry out selective hydrogenation, and stay ethene and hydrogenation does not take place propylene, the operation of the rectifying/conversion zone 60 of tower 56 should make in the liquid phase that most of hydrogenation reaction takes place, have one sizable with respect to C
2And C
3The C of component
4And C
5The component concentrations gradient.This is by adopting height to fall liquid measure, for example adopting high reflux ratio and big inter-stage condensation load to realize in preferred scheme.By overhead condenser 86 and 88, and high reaction heat has also been got rid of in the tower backflow of the interstage cooler of tower or intercondenser 80 generations.
As shown in Figure 2, catalyzer is sub-divided in a series of discrete beds 66,68 and 70.Though only represented three beds, this only is as an example, can be the bed of any number according to the difference of specific device dynamics.These beds are maintained between silk screen or the porous plate 72.Between catalyst bed is collection tray 74, and it comprises steam flow port or bubble-cap 76.The liquid that autocatalysis agent bed is fallen accumulates on separately the tower tray, and enters in the intercepting basin 78.This liquid is removed from intercepting basin 78 as side line, through intercondenser 80, is annotated the top of getting back to the catalyst bed that one deck is lower down in the tower by distribution collector 82 then.This can be discharged from a part of reaction heat in intercondenser.Arrange intercondenser by this way, heat-eliminating medium can be a water coolant, and the heat-eliminating medium in the overhead condenser may need part to utilize mechanical refrigeration.Therefore use intercondenser can reduce that part of reaction heat that needs are got rid of by mechanical refrigeration greatly.
In overhead condenser 86, use water coolant, and 84 coolings of the cat head fraction that in condenser 88, will in tower, discharge with refrigeration agent, in 90 with the steam and the liquid separation that obtain.The course of processing of the steam of collecting in pipeline 94 hereinafter will be discussed.The liquid that obtains in separator 90 is pumped back in the tower through pipeline 96 as refluxing.Many tower trays are provided,, have prevented that they are with respect to C so that rectifying goes out ethene and propylene from liquid phase
4And C
5The high density of component enters beds.
Must limit ethene and the loss of propylene in hydrogenation reaction in the present invention, because they are main productss of ethene or olefin hydrocarbon apparatus.But can carry out C
4Under the conventional conditions of heavier hydrogenation of olefins, the ethene that causes because of hydrogenation and the loss of propylene are high to unacceptable degree.Here it is only makes C in one of prior art processing sequence of introducing that adopts at present in the upstream of deep cooling and condensing steps in preamble
2Alkynes and portion C
3The major cause of alkynes and diene hydrogenation.
Hydrogenation major part in the tower 56 occurs in the liquid phase.Level of response is decided by the relative reactivity of various components and these component concentrations in the liquid phase of any specific point in tower.C
2And C
3The reactive behavior of alkynes and diolefine is higher than ethene and propylene far away, so they at first and promptly react.But ethene, propylene and C
4Heavier alkene, the relative reactivity of diolefine and alkynes is very approaching.In order to react away the C of remarkable quantity
4Heavier alkene, diolefine and alkynes avoid taking place the loss of significant ethene and propylene simultaneously, it is minimum that the concentration of ethene and propylene is reduced to, and must control concentration and temperature distribution at the bottom of from cat head to tower.Owing to be in a rectifying tower, hydrogenation reaction to take place, can reflux by regulating, and realize this control from the side reflux of intercondenser 80 by overhead condenser 86 and 88 cats head that produced (outward).
The temperature of the tower charging 54 under the 1.25MPa that mentions previously (0.69-1.72MPa) pressure is at 25-120 ℃, preferably in 70-90 ℃ the scope.At feed points, the concentration of hydrogen is the highest, and temperature (in rectifying/conversion zone) is the highest, and the concentration of ethene and propylene is minimum in the liquid phase.In this point, C in the liquid phase
4And C
5Component concentrations is maintained in the scope of 10-80 with respect to the concentration of propylene, and is preferably about 25, and C in the liquid phase
4And C
5Concentration then be maintained in the scope of 30-100 preferably about 80 with respect to ethene.C in rectifying/conversion zone
2And C
3This lower concentration fall liquor ratio by height and realize.This height falls that liquor ratio can be leaned on high cat head reflux ratio and/or the backflow that produced by intercondenser 80 realizes.As being explained in conjunction with Fig. 4 after a while, can also assign to provide this height to fall liquor ratio from the reorganization at the bottom of the tower by circulation and cooling.Or rather, by trim the top of column 96, the liquor ratio of falling that interstage cooler 80 and heavy constituent circulations (160 among Fig. 4) provide is equivalent to do not having under intercondenser and the heavy constituent round-robin situation, and the liquid measure of falling that is provided is provided the trim the top of column that leans against in the scope of about 0.2-10.This is equivalent to one and is lower than 0.2 reflux ratio for obtaining of traditional tower that identical overhead product specification operates.At the top of rectifying/conversion zone 60, temperature is 30-80 ℃, preferably 60 ℃, and also because most of hydrogen is reacted away, so hydrogen concentration is very low, C there
4And C
5Component and C
2And C
3The ratio of component is equally very high.Keep these operating parameterss by regulating trim the top of column ratio and intercondenser temperature.Because C
2Alkynes, C
3Alkynes and diolefine, C
4Alkynes, diolefine and alkene, and the C of most
5And C
6Alkynes, the hydrogenation reaction of diolefine and alkene, the 50-90% of institute's hydrogen is reacted away in the cracking feed gas.
The still liquid 98 of tower 56 contains some C
5Component and whole basically C
6Heavier component.In preferred version, this tower still product is sent to the second catalytic distillation hydrogenation tower 100 and goes, with production hydrocracking gasoline.On the other hand, can in the fuel system of device, tower kettle product be burnt, perhaps to prior art is described it is pumped in the traditional fixed bed pyrolysis gasoline hydrogenation treater as preamble.In addition in preferred version shown in Figure 2, from the partial C that comprises of tower 56 discharges
5Component and whole basically C
4More the cat head fraction 94 of all clears of light constituent at first is compressed in 102, and is sent in the hydrogen reclamation film equipment 104.This class film device can have been bought from the market, separates to carry out hydrogen.Using the purpose of film is to reclaim most of hydrogen of still staying in the cat head fraction 94.Then the hydrogen logistics 106 that will obtain and the tower bottoms of tower 56 are fed to pyrolysis gasoline hydrogenation tower 100 together.According to the specific composition of splitting gas, the selection of hydrogen membrane, different with the operational condition of tower 56 may need or not need compression step.On the other hand, can not have to use traditional fixed bed pyrolysis gasoline hydrogenation device under the situation of membrane separation apparatus.Because of occurring in the hydrogenation reaction in the tower 56, the hydrogen that quantity reduces greatly in logistics 94 will be reclaimed by low temperature as previously discussed in the case.
Pyrolysis gasoline is that a kind of scope is from C
5Compound is approximately the complex mixture of 200 ℃ hydro carbons to boiling point.Etidine belongs to the content height of hydrocarbon, and the charging of pyrolysis gasoline tower 100 is extremely unstable.Therefore in the production of pyrolysis gasoline, charging in tower 100 by hydrogenation.Tower 100 is similar with tower 56, and it has typical bottom 108, one reboilers 110 of stripping stage and the top rectifying/conversion zone 112 that hydrogenation catalyst is housed.It comprises an overhead condenser 114 and separator 116, will reflux from separator and 118 return this tower.This tower can comprise or not comprise interstage cooler similar to the intercondenser of tower 56 or intercondenser.In tower 100, remaining C in the charging
5Alkynes, diolefine and alkene, and all C
6Heavier alkynes, diolefine and alkene are by hydrogenation.This tower operates in 0.21-0.86MPa, preferably under the 0.34MPa.C in the charging
8Lighter component enters catalyst bed, alkynes there, and diolefine and alkene are by hydrogenation.C
9Heavier component is discharged from the tower still of tower 100.Reaction heat is withdrawn from by backflow 118.
Backflow 118 also plays the control hydrogenation reaction and optionally acts on.As has been noted, in logistics 106 small amount of ethylene is arranged, this part ethene is a kind of value product, should prevent its hydrogenation.Suitably control tower refluxes 118, can make in the liquid phase of tower ethylene concentration reduce to minimum.This technology can avoid ethene to pass through more desirable with hydrogen than the quality of membrane separating method is brought up to basically.The surface-area that reduces the pressure reduction of film both sides and/or increase film can make ethene pass through reduce to minimum.But the investment intensity that increases the film surface-area is very high, and improving pressure reduction then is that energy expenditure and investment cost intensity are all very high.The ability of the selective hydrogenation of tower 100 then makes the method for a kind of low investment cost and low energy intensity become possibility.To mainly contain C from what tower was discharged
4More the overhead vapours 120 of light constituent is recycled to the feeding side of present method.The final overhead product that will be condensed into liquid in 122 is discharged as pyrolysis gasoline.
Fig. 3 has illustrated overhead stream 94 process hydrogen separating step in 104, becomes logistics 124 to discharge later processing treatment.On the other hand, if do not adopt previously described membrane sepn and pyrolysis gasoline process portion, can directly utilize this system to come process streams 94.Will take extra measure to carry out low temperature hydrogen in this occasion separates.
In 128,, make C as required with steam logistics 124 deep coolings
2Heavier component liquefaction.Then in demethanizing tower 132, make methane overhead product 130 and C
2Heavier tower kettle product 134 separates.Still liquid 134 is further separated in deethanizing column 136, produces a C
2Overhead product 138 and a C
3Heavier bottom product 140.C
2Overhead product 138 can pass through a drying plant (not shown) earlier, and then is separated into ethane tower kettle product 144 and ethene overhead product 146 in tower 142.The tower bottoms 140 of deethanizing column 136 then is separated into a C in tower 148
4Heavier tower kettle product 150 and a C
3Overhead product 152.Overhead product 152 also can be dried earlier, is fed to then to carry out in the tower 154 separating of propane 156 and propylene 158.
Fig. 4 has illustrated a kind of alternate preferred version of the present invention, and it will be from the circulation of the stripping section 58 of tower 56 in conjunction with having entered.In this scheme, the recycle stream 160 from stripping section 58 is recycled in the overhead product 84 through pipeline 161, and/or is recycled in the catalytic domain of rectifying/conversion zone 60 through pipeline 163.It is preferable mostly just being recycled to catalytic domain through pipeline 163.For example, this circulation can be the part 162 of tower kettle product 98 and/or the part 164 in the stripping section.The effect of this circulation 160 is with heavy constituent C
5 +Be recycled to cat head or be recycled to the catalytic domain of tower.This has increased and will perhaps have been also had the quantity of some alkene by the diolefine of hydrogenation and alkynes, thereby has increased the consumption of hydrogen.It also provides another controlled variable, and the temperature of tower top temperature and/or catalyst bed is improved.It is more desirable to improve tower top temperature, because can reduce or cancel like this to producing the required refrigeration demand that refluxes.The temperature that improves catalyst bed provides another to be used to control the variable of catalyzed reaction bed speed of reaction.Though this scheme has been finished the distillation in tower, because at cat head some heavy constituent are arranged now, so be not classical still-process.Can provide some further still-process in the downstream in the case, to obtain required final separation.The purpose of this scheme is to improve occurring in the control of the reaction in the tower 56, and even now can be sacrificed some centrifugations that obtained by distillation.When the operation catalytic distillation tower is arranged under the heavy constituent round-robin condition of cat head, be preferably in 165 heavy constituent are cooled off.When adopting the high cycle rate of heavy constituent, this refrigerative effect may be very big especially.Falling under the liquid speed of equating, it reduces the reflux ratio of catalytic distillation tower.If adopt the side line cooling, reflux rate also can further reduce.The final effect of all these cooling steps is to greatly reduce reflux ratio.Because can under higher condensing temperature, provide condensation reflux liquid required part cooling effect, therefore may reduce the refrigeration demand.This may be that heavy constituent section at the bottom of the tower is recycled to the tower epimere, especially is recycled to another benefit of vapor outlet port 84, because this will improve tower top temperature and reduce refrigeration demand.
When operating catalytic distillation tower under still liquid round-robin situation is arranged, trim the top of column is than in the scope of 0.05-0.4, preferably at the 0.1-0.2 that still liquid is circulated when pipeline 163 is introduced the catalyst bed tops.Still liquid is being circulated when pipeline 161 is introduced cats head, reflux ratio is 0.2-10.Even but use this lower trim the top of column ratio, in beds, circulation and cooling by intercondenser and heavy constituent have still kept a high liquor ratio of falling.The heavy constituent circulation does not meet " classics " still-process that people think, because circulation has caused some by the loss of distilling the final separation benefit that is produced.But to make in the catalyst zone liquid ethene and density of propylene reduce to minimum because of using height to fall liquid speed, and improve the benefit that reaction bed temperature brought and but surpassed this loss.
The present invention before deep cooling and condensing steps, remove splitting gas contained 85% to almost 100%, the ability that is generally 90% hydrogen has reduced energy expenditure and investment cost.Utilize hydrogen contained in the splitting gas to get rid of demand to independent low temperature hydrogen sepn process as the sources of hydrogen of various hydrogenation reactions.Concentration distribution by in the suitable control catalytic distillation hydrogenation tower can make C
4Heavier hydrogenation of olefins does not but make the significant hydrogenation of any generation in ethene or the propylene.Therefore hydrogenation reaction is incorporated in one or two reactor assembly.
Claims (16)
1. method of processing through the feed stream of thermo-cracking, this feed stream contain hydrogen, ethene, propylene, and other C that produces in said thermal cracking processes
2, C
3, C
4, C
5, C
6Heavier unsaturated hydro carbons, said ethene and propylene are separated with some said other unsaturated hydrocarbons at least, and with the said hydrogen that comprises in the said feed stream some said other hydrogenation of unsaturated hydrocarbons at least, and do not need from feed stream, to isolate in advance said hydrogen, and do not make the remarkable hydrogenation of said ethene and propylene, this method may further comprise the steps:
A. said feed stream is introduced the intake zone of a distillation reaction tower, this tower comprises a rectifying and a catalytic reaction zone in a stripping zone below the said intake zone and a combination above said intake zone;
B. simultaneously:
Said feed stream and the rectifying of said combination in the said distillation reaction tower are contacted with a vertical orientated hydrogenation catalyst bed in the catalytic reaction zone;
Ii. keep a C in said vertical orientated hydrogenation catalyst bed bottom
4And C
5Hydro carbons total amount and C
2And C
3The height ratio of hydro carbons total amount is selected said height ratio, thereby makes said ethene and propylene keep basically not hydrogenation, said other unsaturated hydrocarbons at least some then by hydrogenation;
Iii. the resulting hydrogenation of rectifying and the not product mixture of hydrogenation;
C. take out one and comprise all said C basically
2, C
3And C
4Hydro carbons, and a part of said C
5The overhead stream of hydro carbons, and one comprise all said C basically
6Heavier hydro carbons, and a part of said C
5The tower base stream of hydro carbons; And
D. process said overhead stream, to reclaim ethene and propylene.
2. the described working method of claim 1, wherein said feed stream comprises C
9Heavier component, and the said step (d) of processing said overhead stream may further comprise the steps:
A. from said overhead stream, isolate hydrogen;
B. be fed in the pyrolysis gasoline distillation reaction tower that a kind of hydrogenation catalyst is housed with said separated hydrogen with from the said tower base stream of said distillation reaction tower;
C. in said pyrolysis gasoline distillation reaction tower, make the reaction of said separated hydrogen and said tower base stream, produce pyrolysis gasoline liquid overhead product and C of a hydrogenation
9Liquid at the bottom of the tower of heavy constituent more.
3. the described working method of claim 2, wherein the step of said separating hydrogen gas comprises the step by a kind of hydrogen separation membrane separating hydrogen gas from said overhead stream.
4. the described working method of claim 1, the step of a height ratio of wherein said maintenance comprises that a chosen point from said hydrogenation catalyst bed extracts at least a portion dropping liq as a side-stream, cool off said side-stream, and the said side-stream that is cooled is annotated the step of getting back to said hydrogenation catalyst bed.
5. the described working method of claim 4, wherein said side-stream are got back to a position below said chosen point of said bed by notes.
6. the described working method of claim 1, wherein said hydrogenation reaction takes place in the liquid phase of said distillation reaction tower basically.
7. method of processing through the feed stream of thermo-cracking, this feed stream contain hydrogen, ethene, propylene, and other C
2, C
3, C
4Heavier unsaturated hydrocarbons, with the said hydrogen hydrogenation that comprises in the said feed stream some said unsaturated hydrocarbons at least, and not said ethene of hydrogenation and propylene, this method may further comprise the steps:
A. said feed stream is introduced the intake zone of a distillation reaction tower, this tower comprises a rectifying and a catalytic reaction zone in a stripping zone below the said intake zone and a combination above said intake zone;
B. simultaneously
(i) the said feed stream in the said distillation reaction tower is contacted with vertical orientated hydrogenation catalyst bed in the catalytic reaction zone in the rectifying of said combination with one;
(ii) maintain in the said hydrogenation catalyst bed, comprise a C
4More heavy hydrocarbons and C
2And C
3The height ratio of hydro carbons is selected said height ratio in interior hydrogenation conditions, thereby makes said ethene and propylene keep basically not hydrogenation, and makes all said other C basically
2, C
3, C
4Heavier hydrogenation of unsaturated hydrocarbons;
The (iii) resulting hydrogenation of rectifying and the not mixture of the product of hydrogenation;
(iv) heavy constituent are recycled to a position of the said catalytic reaction zone top of said tower from said stripping zone, to help keeping said height ratio, improve the temperature of said catalytic reaction zone and provide extra will be by the unsaturated hydrocarbons of hydrogenation;
C. take out one and contain in fact all said C
2, C
3, and C
4Hydro carbons reaches the overhead stream of the heavier hydro carbons of a part and the tower base stream of a heavier hydro carbons that contains rest part; And
D. process said overhead stream, to reclaim ethene and propylene.
8. the described working method of claim 7, the step of wherein said circulation heavy constituent are included in introduces the step of cooling off said heavy constituent before the said tower.
9. the described working method of claim 8, the step of a height ratio of wherein said maintenance comprises that a chosen point from said hydrogenation catalyst bed extracts at least a portion dropping liq as a side-stream, cool off said side-stream, and the said side-stream that will be cooled is annotated the step of getting back to said hydrogenation catalyst bed.
10. the described working method of claim 9, the step of a height ratio of wherein said maintenance also comprise the step of the high reflux ratio that keeps the rectifying of getting back to said combination and catalytic reaction zone.
11. the described working method of claim 10, wherein said reflux ratio is in the scope of 0.05-0.4.
12. the described working method of claim 10, wherein said reflux ratio is in the scope of 0.1-0.2.
13. comprising, the described working method of claim 7, the wherein said step that heavy constituent are recycled to a position above said catalytic reaction zone of said tower be recycled in the said overhead stream that is removed.
14. the described working method of claim 13, the step of a height ratio of wherein said maintenance also comprise the step of the high reflux ratio that keeps the rectifying of getting back to said combination and catalytic reaction zone.
15. the described working method of claim 14, wherein said reflux ratio is in the scope of 0.5-1.5.
16. the described working method of claim 14, wherein said reflux ratio is in the scope of 0.2-10.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB971817693A CN1152946C (en) | 1997-02-19 | 1997-02-19 | Olefin plant recovery system employing catalytic distillation |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB971817693A CN1152946C (en) | 1997-02-19 | 1997-02-19 | Olefin plant recovery system employing catalytic distillation |
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| Publication Number | Publication Date |
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| CN1246140A CN1246140A (en) | 2000-03-01 |
| CN1152946C true CN1152946C (en) | 2004-06-09 |
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| CNB971817693A Expired - Fee Related CN1152946C (en) | 1997-02-19 | 1997-02-19 | Olefin plant recovery system employing catalytic distillation |
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| US20220380692A1 (en) * | 2019-10-31 | 2022-12-01 | Eastman Chemical Company | Processes and systems for formation of recycle-content hydrocarbon compositions |
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