CN105439799B - A kind of system and method recycling ethylene from high propylene lighter hydrocarbons or preparing propylene from methanol product gas - Google Patents
A kind of system and method recycling ethylene from high propylene lighter hydrocarbons or preparing propylene from methanol product gas Download PDFInfo
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- CN105439799B CN105439799B CN201410410619.XA CN201410410619A CN105439799B CN 105439799 B CN105439799 B CN 105439799B CN 201410410619 A CN201410410619 A CN 201410410619A CN 105439799 B CN105439799 B CN 105439799B
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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Abstract
The invention discloses a kind of from high propylene lighter hydrocarbons or preparing propylene from methanol product gas recycles the system and method for ethylene.System includes:First, second dethanizer, drier, hydrogenation reactor, domethanizing column, domethanizing column tail gas recycle unit, ethylene rectifying column, the domethanizing column tail gas recycle unit are made of combined absorbing tower, expanding machine and the second knockout drum；The top of combined absorbing tower is cryogenic rectification tower section, and lower part is to absorb tower section.The present invention using front-end deethanization front-end hydrogenation, double tower deethanization, in cold C3~C6Light hydrocarbon mixture absorbs domethanizing column tail gas, and absorbent comes from the first dethanizer and depropanizing tower bottom product, the second dethanizer and the direct thermal coupling of ethylene rectifying column.The present invention can improve device Recovery rate of ethylene, reduce absorbent loss, further decrease energy consumption and the investment of product gas ethylene recovery part.
Description
Technical field
The present invention relates to the low-carbon alkene field of refinement of high propylene content, further say, are to be related to one kind from high propylene
The system and method for ethylene is recycled in lighter hydrocarbons or preparing propylene from methanol product gas.
Background technology
Ethylene, propylene are the basic materials of petro chemical industry, with the development of economy, the scarcity of petroleum resources, as
The raw materials such as naphtha, the light diesel fuel of ethylene production raw material face increasingly severe short situation.With the need of ethylene and propylene
It asks and increases year by year, for propylene/ethylene demand than in rising trend, propylene/ethylene output ratio is on a declining curve, therefore, catalytic pyrolysis
(CPP containing producing olefin hydrocarbon by catalytic pyrolysis, Deep catalytic cracking DCC, olefins by catalytic cracking OCC, Superflex and ACO), methanol alkene
Hydrocarbon (MTO) or preparing propylene from methanol (MTP) etc. come into being by purpose low-carbon alkene production technology of propylene enhancing, especially with coal
Base synthesis gas propylene, methane dehydrogenation are coupled the technologies such as propylene processed and have opened up cheap propylene feedstocks source.
The propylene and ethylene mass ratio (P/E) of these olefin producing technologies is usually then big in the P/E of 0.6 or more, MTO and MTP
In 1, the wherein P/E of MTP>>1, and the P/E of conventional vapor cracking ethylene preparation device is usually below 0.5.Conventional naphtha steam
Methane hydrogen content is higher in cracking gas, generally uses cryogenic method separation of methane and ethylene.Deep cooling separating method is required to -100
DEG C Cryogenic Conditions, need ethylene refrigeration compressor, or even methane refrigeration compressor is needed to provide cold for it.Device is to ice chest
It is required that high so that construction investment increases, and energy consumption of compressor rises.
For the low-carbon alkenes production technology, especially coal base such as CPP, DCC, OCC, Superflex and ACO, MTO or MTP
Methane hydrogen content is relatively low in the product gas such as synthesis gas propylene, methane dehydrogenation coupling propylene, MTO and MTP processed, and propylene, ethylene contain
Amount is high, and the high-carbon hydrocarbon content of six or more carbon is less, and the cold that domethanizing column needs is relatively small.
US7714180 proposes a kind of process of olefin recovery.According to this method, product gas passes through first after compression
Cross debutanizing tower removing C5 +Heavy constituent, the C come out from tower top4Light component is further compressed, and successively enters demethanation after cooling
Tower, dethanizer, depropanizing tower, depropanizing tower bottom of tower mixing carbon four make absorbent and domethanizing column are gone to absorb the second in tower overhead gas
Alkene improves Recovery rate of ethylene.
The invention avoids using deep cooling process for separating, but uses oily absorption technique, reduces investment.But using mixed
It closes four absorbent internal circulating load of carbon greatly and long flow path, energy consumption is big.If contain more butadiene in carbon four, downstream can be made related
Equipment coking is serious.
Chinese patent 200810201217.3 proposes a kind of separation method of lighter hydrocarbons in MTO/MTP product gas.According to this
Method is directly entered dethanizer, tower top C after light hydrocarbon product pretreatment2Light component enters back into absorption tower, makes and absorbs of ethane
Agent, to improve Recovery rate of ethylene.It is avoided in this way using ethylene refrigeration compressor, absorbent, portion is done using ethane
Divide ethane to be lost from absorption tower tower top and makees fuel gas, but when the ethane that reaction process generates is less than the ethane of absorption tower loss
When, absorbent is made with regard to improper using ethane.
CN101973831A has invented a kind of low-carbon alkene separation method.Using predepropanization separation process.De- third
Alkane column overhead C3Light component enters domethanizing column after further compressing cooling, and the very useful ethane of demethanizer makees absorbent, to carry
The rate of recovery of high ethylene.Domethanizing column bottom of tower two~carbon of carbon three goes dethanizer to carry out the separation of carbon two and carbon three, and carbon two is into second
Alkene rectifying column, side take-off ethylene, tower top fixed gas return to compressor, are absorbed as domethanizing column after ethane whole in bottom of tower is cooling
Agent or part are produced as fuel gas.Carbon three goes propylene rectification tower, overhead extraction propylene, bottom of tower extraction propane to do LPG byproducts.
In view of the ethane amount that some reaction process generate is less, which smokes part propane from propylene tower bottom of tower and does ethane absorption agent
Supplement.
Because using ethane to make absorbent, ethane content is 20% or more in demethanizer column overhead tail gas.Absorbent is in flow
In longer circulating path, absorbent the energy consumption of device is both increased to the dilution of ethylene column and propylene tower input concentration.
When making absorbent with ethane, ethane content is very high in the tower top tail gas of absorption tower, and large size MTO/MTP devices will often follow
Cyclohexane carries out steam cracking, and the recycling and tail gas loss problem of ethane are fully considered when making absorbent with ethane.
CN100398498C discloses a kind of separation method of methanol preparing low-carbon olefin by conversion (DMTO) gas, most conventional
Front-end deethanization separation process is improved four sections of compressed flows.According to the invention, at five sections, compression and dethanizer return
Hydro-conversion is designed between stream tank, removes the oxide generated during acetylene and reaction regeneration, condenses logistics warp after cooling
Deethanizer reflux tank, for liquid phase as deethanizer reflux, gas phase enters deep cooling domethanizing column.
CN101353286A proposes a kind of non-copious cooling lower carbon number hydrocarbons separation method.This method goes out pretreated reactor
Gas is sent to precut tower (domethanizing column) after being cooled to 10 DEG C~-37 DEG C.It precuts column overhead hydrogen containing methane, carbon two and lacks
The tail gas for measuring carbon three cools down laggard absorption tower, and the absorbent formed with the mixture of carbon three, carbon four, light dydrocarbon and hydro carbons will be precut
C 2 hydrocarbon class in tower overhead absorbs, and light gas is discharged by top, and absorption tower bottom product, which returns, precuts tower
(domethanizing column)；The product of precut tower (domethanizing column) tower reactor carbon containing two and more heavy constituent carries out carbon two and carbon into dethanizer
Three cleaning cuttings, tower top obtain C-2-fraction；Tower reactor obtains carbon three and more heavy constituent.The patent precuts column overhead tail gas and suction
It receives agent to be required for being cooled down with ethylene cryogen, a large amount of absorbents in tail gas cannot be recycled effectively, be burnt in vain.The patent is only fitted
Preparing propylene from methanol is not suitable for it such as methanol-to-olefins (MTO) for the technique of product gas propylene and ethylene mass ratio (P/E)≤P
(MTP) this P/E>>1 olefin process.
CN202081036U has invented a kind of method of MTP product gas lighter hydrocarbons separation, which uses predepropanization process.
After two sections of compressions of product gas, enters compressor third section through washing, alkali cleaning and compressed, compressed product gas process cohesion,
Dry laggard depropanizing tower.Condensed liquid stripper is provided between compressor section, it is light in lime set between compressor section for detaching
Hydrocarbon.Light hydrocarbon gas at the top of condensate stripper returns to two sections of entrances of compressor, and the heavy hydrocarbon of bottom of tower is sent to debutanizing tower.Depropanizing tower
It is located between three sections and four sections of compressor, and uses conventional rectification；Depropanizing tower top gaseous phase product is through four sections of compressions of compressor
Laggard dethanizer, bottom product carbon elimination four recycle；Deethanizer overhead product is into domethanizing column, and bottom product is into propylene rectifying
Tower；Demethanizer column overhead places tail gas subcooler, recycles itself cold with throttling refrigeration mode and reduces ethylene loss, bottom of tower production
Product are into ethylene rectifying column.The patent has substantially continued the mentality of designing of traditional MTP devices, and demethanizer column overhead uses ethylene cold
Agent, plant energy consumption problem do not obtain too big improvement.
CN101747128B discloses a kind of separation method of methane low carbon olefin gas, to solve to take off in the prior art
The big disadvantage of ethylene loss in methane overhead gas.The patent is characterized in that expanding machine is arranged in demethanation tower top, in demethanation
Built-in cold condenser is set in tower, and the gaseous stream in domethanizing column is cooled to -45 DEG C~-60 by built-in cold condenser
DEG C, the gas phase being ejected from demethanizer enters expanding machine, temperature is subcooled to -90 DEG C~-120 DEG C, pressure drops to
0.1MPaG~0.6MPaG, the logistics for going out expanding machine carry out gas-liquid separation, wherein go out battery limit (BL), liquid phase stream after gas stream re-heat
Into the first two section of suction tank of gas compressor, or domethanizing column is returned to, domethanizing column bottoms stream is divided into other separation of olefins units
Ethylene and propylene product are separated out, the domethanizing column absorbent is one or more of C3, C4 and C5+ fraction substance.
Condenser built in domethanizing column in the patent is actually the segregative dephlegmator frequently referred on ethylene unit
(Dephlegmator), the exceeded phenomenon of ethylene contents in tail gas is frequently encountered when similar techniques practical application.
CN102476976A has invented a kind of method of absorption and separation recycling lighter hydrocarbons, which uses front-end deethanization flow,
Use C3H6、C4Or C5 liquid hydrocarbons make absorbent, recycle the ethylene in domethanizing column tail gas, the absorbent rich solution at absorption tower bottom returns
Front-end deethanization tower is desorbed.The patent there is no in tail gas from absorption tower alkene and absorbent recovery method do further sound
It is bright.
The quality of low-carbon alkene separation method is mainly reflected in three energy consumption, product recovery rate and synthetic analysis sides
Face, especially product recovery rate and energy consumption.Domethanizing column, ethylene distillation mainly occur for low-carbon alkene separation process ethylene loss
Tower, and domethanizing column system ethylene loss accounts for 60% or more of olefin separation system ethylene loss, the energy consumption of domethanizing column system
It reduces and plant energy consumption reduction is played a crucial role.
Many patents all claim that absorbent can be carbon four or light dydrocarbon, but in the specific implementation, carbon four or light dydrocarbon absorbent
From the subsequent depropanizing tower of flow or debutanizing tower, the rich absorbent at absorbing tower bottom needs to complete by two or three of towers
Regeneration cycle needs repeatedly to boil and condense again, and equipment investment and energy consumption are all uneconomical.
Individual patents propose that methanol-to-olefins device domethanizing column tail gas can be recycled using low-temperature expansion, and these
The tail gas recycle technology being made of ice chest, expanding machine as defined in patent expands condensation skill with conventional ethylene device domethanizing column tail gas
Relatively, cooling capacity utilization rate is not high for art.
It is necessary to find targetedly high propylene lighter hydrocarbons or preparing propylene from methanol (MTP) product gas ethylene recovery technology.
Invention content
To solve the problem in the prior art, the present invention provides one kind to produce from high propylene lighter hydrocarbons or preparing propylene from methanol
The system and method for ethylene is recycled in product gas.Device Recovery rate of ethylene can be improved, absorbent loss is reduced, further decreases product
The energy consumption of gas ethylene recovery part and investment.
An object of the present invention, which is to provide, a kind of recycling ethylene from the high propylene lighter hydrocarbons or preparing propylene from methanol product gas
System.
Including:First, second dethanizer, drier, hydrogenation reactor, domethanizing column, domethanizing column tail gas recycle list
Member, ethylene rectifying column,
The domethanizing column tail gas recycle unit is made of combined absorbing tower, expanding machine and the second knockout drum；Combination
The top on absorption tower is cryogenic rectification tower section, and lower part is to absorb tower section；
Drier and hydrogenation reactor are sequentially connected at the top of first dethanizer, hydrogenation reactor lower part connects demethanation
Tower；First Deethanizer bottom pipeline is divided into two, respectively connected the absorption tower section and depropanizing tower of combined absorbing tower；
Demethanizer overhead connects combined absorbing tower lower part, and expanding machine and the second gas-liquid are sequentially connected at the top of combined absorbing tower
Knockout drum；Second knockout drum gas, liquid outlet line is respectively fed to the cryogenic rectification tower section of combined absorbing tower, vapor delivery line
Recompression machine is connected after cryogenic rectification tower section to send out out-of-bounds；Liquid phase pipeline is sent out out-of-bounds after cryogenic rectification tower section；Combination is inhaled
It receives tower bottom and connects the first dethanizer top；
Demethanizer bottom connects the second dethanizer, and ethylene rectifying column, ethylene distillation are connected at the top of the second dethanizer
Tower side line sets side line outlet connection and takes off the second ethane tower；
Depropanizing tower outlet at bottom pipeline is divided into two, and one is sent out out-of-bounds, one and the first Deethanizer bottom pipeline
The absorption tower section of combined absorbing tower is connected after merging.
The second object of the present invention is to provide a kind of to recycle ethylene from the high propylene lighter hydrocarbons or preparing propylene from methanol product gas
Method.
Including：
(1) product gas enters the first dethanizer, and the first deethanizer overhead gas products sequentially enter drier and add
Hydrogen reactor enters domethanizing column after hydrogenated postcooling；First dethanizer bottom of tower fraction of stream is sent into tail gas recycle unit
Combined absorbing tower as absorbent, rest part removes depropanizing tower；
(2) demethanizer column overhead tail gas recycles ethylene into tail gas recycle unit, and bottom of tower liquid phase is into the second dethanizer；
(3) second deethanizer overhead gas phases obtain qualified ethylene product into ethylene rectifying column, and bottom of tower liquid phase is into propylene
Rectifying column obtains qualified propylene product；
(4) it goes to combine as absorbent after depropanizing tower bottom of tower fraction of stream merges with the first Deethanizer bottom point logistics
Absorption tower, remaining product are gone out-of-bounds.
Wherein,
In step (2), domethanizing column tail gas enters the absorption tower section of combined absorbing tower from bottom, and absorbent is from absorbing tower section
Top enter, the absorbent rich solution for absorbing tower section bottom returns to the first dethanizer, absorber portion top gas continue up into
Enter the cryogenic rectification tower section of combined absorbing tower；
Combined absorbing tower top gas phase passes through expansion, gas-liquid split-phase, and combined absorbing tower is passed through in the logistics after split-phase respectively
After cryogenic rectification tower section re-heat, into subsequent handling.
Enter ethylene rectifying column after second deethanizer overhead gas throttling, from one liquid of ethylene rectifying column lateral line withdrawal function
Material is sent to the second deethanizer overhead, as the second deethanizer reflux.
In the present invention, common operating condition in the prior art, the skill of this field may be used in the process conditions of each equipment
Art personnel can be adjusted according to actual conditions.
In the present invention, preferably:
First deethanizer overhead preferred operations pressure is 2.8MPaG~3.2MPaG, and preferred operations temperature is 13 DEG C~25
℃；
Demethanizer column overhead preferred operations pressure is 2.4MPaG~3.0MPaG, and preferred operations temperature is -35 DEG C.
Following technical scheme specifically can be used in the present invention:
Including：First dethanizer, depropanizing tower, drier, hydrogenation reactor, domethanizing column, domethanizing column tail gas return
Receive unit, the second dethanizer and ethylene rectifying column that " coupling " is thermally integrated.
1 double tower deethanization of the present invention:
Product gas through overcompression, purification enters the first dethanizer, the first preferred 2.8MPaG of deethanizer overhead pressure
~3.2MPaG.First deethanizer overhead gas successively passes through drying unit and hydrogenation unit, after adding the product air cooling after hydrogen
Into domethanizing column.Demethanizer column overhead tail gas enters exhaust gas recovery system recycling ethylene, and bottom product enters the second de- second
Alkane tower.
First dethanizer part bottom product goes domethanizing column tail gas recycle unit, rest part to go to take off as absorbent
Propane tower.
2 tail gas recycle units are made of combined absorbing tower, expanding machine and the second knockout drum.
(1) combined absorbing tower top is the cryogenic rectification tower section that preferred operating temperature is -35 DEG C~-108 DEG C, and lower part is to inhale
Receive tower section.
(2) cryogenic rectification tower section is the plate-fin segregative dephlegmator that an inside is full of fractional distillation filling-material,
(3) demethanizer column overhead tail gas enters the absorption tower section of combined absorbing tower from bottom, is then upwardly into deep cooling essence
Evaporate tower section, a part of the cryogenic rectification tower section bottom liquid phases logistics as absorber portion absorbent, by flow by gravity to absorption tower
Section top.Through swollen after preferable temperature pressure is -99 DEG C~-108 DEG C, the cryogenic rectification tower section top gas of 2.5MPaG comes out
Swollen machine swell refrigeration, the material for going out expanding machine carry out gas-liquid separation into knockout drum, and the liquid phase separated passes through respectively
Cryogenic rectification tower section carries out re-heat, and the gas phase after re-heat goes fuel gas system after the boosting of recompression machine, and the liquid phase after re-heat is gone
Out-of-bounds.
3 depropanizing tower tower top liquid-phase products go propylene rectification tower, bottom of tower portioned product to remove domethanizing column tail as absorbent
Gas recovery unit, remaining product are gone out-of-bounds.
First 4 absorbents of the present invention are to be rich in C3~C6 liquid hydrocarbon mixtures from the first dethanizer bottom of tower,
In addition it is to be rich in C4~C6 liquid hydrocarbon mixtures from depropanizing tower bottom of tower.
5 inventions are described " coupling " the second dethanizer and ethylene rectifying column that are thermally integrated, it is mainly characterized by：Second is de-
Ethane tower and ethylene rectifying column use " thermal coupling " form combines, and the second dethanizer does not set overhead condenser and return tank, and
Second deethanizer overhead is pumped into using one liquid material from ethylene rectifying column lateral line withdrawal function, is returned as the second dethanizer
Stream.
The method specific steps that ethylene is recycled from high propylene lighter hydrocarbons or preparing propylene from methanol (MTP) product gas of 6 present invention
Including.
(1) enter the first dethanizer after preprocessed, boosting product air cooling, top gaseous phase product is respectively through overdrying
Dry and hydrogenation reaction, domethanizing column after the logistics cooling that hydrogenation reactor comes out, bottom of tower Partial Liquid Phase product are gone as absorbent
Domethanizing column tail gas recycle unit, rest part remove depropanizing tower.
(2) demethanizer column overhead tail gas enters domethanizing column exhaust gas recovery system and continues to recycle ethylene and absorbent, piptonychia
Alkane tower bottom product removes the second dethanizer.
(3) demethanizer column overhead tail gas enters the absorption tower section of combined absorbing tower from bottom, and gas continues in absorber portion
The cryogenic rectification tower section on combined absorbing tower top is gone upward to, cryogenic rectification tower section bottom liquid phases material is as absorption tower section absorbent
A part, flow automatically at the top of absorption tower, cryogenic rectification section tail gas then enters directly into expander refrigeration.
Absorbing liquid is from absorbing at the top of tower section into combined absorbing tower, the absorbent rich solution re-heat of combined absorbing tower bottom of tower out
Laggard first dethanizer.
(4) tail gas from the top of combined absorbing tower cryogenic rectification tower section out, the expanded refrigeration of the tail gas go out expanding machine
Material carries out gas-liquid separation into knockout drum, and the liquid phase separated passes through cryogenic rectification tower section re-heat respectively, after re-heat
Gas phase through recompression machine boosting after go fuel gas system, the liquid phase after re-heat removes three sections of suction tanks of product air compressor.
(5) second dethanizers and ethylene rectifying column are combined using " coupling " mode of being thermally integrated, and the second dethanizer is not set
Set overhead condenser and return tank.The second laggard ethylene rectifying column of deethanizer overhead gas phase reducing pressure by regulating flow, obtains qualified ethylene
Product, ethylene rectifying column tower top pressure are not less than 1.651MPaG.From ethylene rectifying column lateral line withdrawal function, one liquid material is pumped into
Second deethanizer overhead, as the second deethanizer reflux.
(6) depropanizing tower overhead product goes propylene rectification tower, bottom of tower portioned product to remove domethanizing column tail gas as absorbent
Recovery unit, outside rest part out-of-bounds.
The system and method for the present invention is suitable for all rich commercial plants for producing low-carbon alkene, such as methanol-to-olefins (MTO)
Device, methanol aromatic hydrocarbons (MTA) device, methane dehydrogenation are coupled propylene or coal based synthetic gas propylene unit processed, are preferably applied to
MTP devices.
The present invention and prior art comparison have the superiority of several aspects：
(1) the domethanizing column exhaust gas recovery system for using combined absorbing tower, expanding machine and ice chest composition, can be effectively reduced
The loss of ethylene and absorbent in tail gas improves the utilization rate and yield of ethene of cryogenic energy.
(2) present invention is using front-end deethanization front-end hydrogenation, double tower deethanization technology, with first dethanizer bottom of tower C3~C6 hydrocarbon
Mixture and depropanizing tower bottom of tower C4~C6 hydrocarbon mixtures make absorbent, and absorbent rich solution returns to the first dethanizer, improves
The operating characteristics of domethanizing column.
Absorbent circulation process is shorter, and molecular weight is big so that relevant apparatus becomes smaller in size.
(3) the absorbent rich solution that combined absorbing tower bottom of tower proposed by the present invention comes out returns to the first dethanizer, especially suitable
For this P/E of MTP>>1 special circumstances.
(4) of the invention by the second dethanizer and ethylene column " thermal coupling " it integrates, reduce the consumption of system cryogen.
Present invention is generally directed to from P/E>>Ethylene is recycled in 1 MTP product gas and domethanizing column system is improved,
It is equally applicable to the commercial plant that other richnesses produce high propylene content low carbon olefin gas, as producing olefin hydrocarbon by catalytic pyrolysis CPP, depth are urged
Change cracking DCC, olefins by catalytic cracking OCC, Superflex, ACO etc..
Description of the drawings
The system flow chart of ethylene is recycled in the slave MTP product gas of Fig. 1 present invention.
Reference sign：
Device flag explanation：
The first dethanizers of 1-, 2- driers, 3- hydrogenation reactors, 4 knockout drums ,-domethanizing column, 6- domethanizing columns
Built-in plate-fins condenser (or built-in CFT), 7-- combined absorbing towers, 8- absorb tower section, 9- cryogenic rectifications tower section, the second gas of 10-
Liquid knockout drum, 11- expanding machines, 12- recompress machine, the second dethanizers of 13-, 14- ethylene rectifying columns, 15- depropanizing towers.
Logistics description of symbols：
100- product gas, the expander outlet liquid phase after 102- re-heats, 103- recompress the tail gas of machine outlet, and 104- is qualified
Ethylene product, 105- ethane products, 106- the second dethanizer bottom products, 107- depropanizing tower overhead products, 108- is de-
Propane tower bottom product, 109- absorbents.
Specific implementation mode
With reference to embodiment, further illustrate the present invention.
Embodiment：
As shown in Figure 1, a kind of system recycling ethylene from high propylene lighter hydrocarbons or preparing propylene from methanol product gas.
Including：First dethanizer 1, depropanizing tower 15, drier 2, hydrogenation reactor 3, domethanizing column 5, domethanizing column
Tail gas recycle unit, the second dethanizer 13 and ethylene rectifying column 14；
The tail gas recycle unit is made of combined absorbing tower 7, expanding machine 11 and the second knockout drum 10；Combination absorbs
The top of tower 7 is cryogenic rectification tower section 9, and lower part is to absorb tower section 8；
Hydrogenation reactor 3 is reconnected after first dethanizer, 1 top connection drier 2,3 lower part of hydrogenation reactor connects gas
Liquid knockout drum 4, knockout drum 4 connect domethanizing column 5；
First dethanizer, 1 bottom line is divided into two, is separately connected the absorption tower of depropanizing tower 15 and combined absorbing tower 7
Section 8；5 top 7 lower part of connection combined absorbing tower of domethanizing column, 7 tower top of combined absorbing tower connect expanding machine 11, and expanding machine 11 exports
Connect the second knockout drum 10；Second knockout drum, 10 gas, liquid outlet line is respectively fed to the deep cooling of combined absorbing tower 7
Rectifying tower section 9, vapor delivery line connect recompression machine 12 after cryogenic rectification tower section and send out out-of-bounds；Liquid phase pipeline is through cryogenic rectification tower
It is sent out out-of-bounds after section；
5 bottom of domethanizing column connects the second dethanizer 13, and 13 top of the second dethanizer connects ethylene rectifying column 14, second
14 side line of alkene rectifying column setting outlet, the second dethanizer 13 of side line outlet connection.
15 bottom of tower fraction of stream of depropanizing tower goes to combine suction as absorbent after mixing with the first Deethanizer bottom logistics
Tower 7 is received, rest part is gone out-of-bounds.
The method of recycling ethylene includes in high propylene lighter hydrocarbons or preparing propylene from methanol product gas：
(1) enter the first dethanizer 1 after washing, compression, alkali cleaning, removing impurities matter product gas 100 cool down.
It is limited that 1 top gas phase product of (2) first dethanizer goes hydrogenation reactor 3 plus hydrogen to remove after the drying of drier 2
Alkadienes and alkynes, it is cooling after enter return tank 4.It is real that the liquid phase of 4 top and bottom of return tank respectively enters domethanizing column 5
The separation of existing carbon one and the second-class heavy constituent mixture of carbon.
First dethanizer, a 1 bottom product part removes combined absorbing tower 7 as absorbent, and rest part is into depropanizing tower
15。
(3) 15 bottom of tower portioned product of depropanizing tower removes combined absorbing tower 7 as absorbent, and rest part is gone out-of-bounds.
(4) operating temperature of condenser 6 built in 5 tower top of domethanizing column is -35 DEG C, and tower top tail gas is directly entered combination and absorbs
Ethylene is recycled in the bottom of tower 7, and domethanizing column bottom of tower liquid phase removes the second dethanizer 13.
(5) for domethanizing column tail gas recycle unit：
7 absorber portion of combined absorbing tower, 8 top exit is directly ined succession cryogenic rectification tower section 9, domethanizing column tail gas 4 from bottom into
Enter to absorb tower section 8, then enters cryogenic rectification tower section 9,9 technique side bottom liquid phase of cryogenic rectification tower section from the top for absorbing tower section 8
The top for absorbing tower section 8 is returned to by gravity, is entered after expanded 11 swell refrigeration of machine of fixed gas at 9 top of cryogenic rectification tower section
Second knockout drum 10.
It boosts through 9 re-heat of cryogenic rectification tower section, recompression machine 12 after the throttling of second knockout drum, 10 top fixed gas 103
Go fuel gas system, 10 bottom liquid of the second knockout drum is through laggard first dethanizer of 9 re-heat of cryogenic rectification tower section 1.
Absorbing liquid 109 from the first Deethanizer bottom enters the top that combined absorbing tower 7 absorbs tower section 8, and from group
It closes 7 bottom of tower of absorption tower and returns to the first dethanizer 1.
13 top gaseous phase product of (6) second dethanizer enters ethylene rectifying column 14 and obtains qualified ethylene product 104, together
When from ethylene rectifying column 14 extract out one liquid phase as phegma return the second dethanizer 13,13 tower bottom liquid of the second dethanizer
Phase product 106 obtains qualified propylene product into propylene rectification tower.
First dethanizer charging, 100 composition is shown in Table 1.
Table 1
Using the Provision7.0 process simulation softwares of general Simsci companies, to the flow scheme of the present embodiment into
Row simulation, obtains simulating result of calculation shown in table 2.
Result of calculation shows that method using the present invention detaches MTP product gas, the production for pot outlet of giving up from reactor
Product gas is to qualified ethylene product, Recovery rate of ethylene 99.64%.
Key stream composition is shown in Table 2.
Table 2
Comparative example 1
Based on the charging of 1 first dethanizer of embodiment, recycled using the technical solution of patent CN101353286A
Ethylene in tail gas.The loss of ethylene and absorbent, is shown in Table 3.
Comparative example 2
Based on the charging of 1 first dethanizer of embodiment, recycled using the technical solution of patent CN101747128B
Ethylene in tail gas.The loss of ethylene and absorbent, is shown in Table 3.
Table 3
As can be seen from Table 3, ethylene loss is 120.0T/A, absorbent (C4~C6) loss in CN101353286A tail gas
For 912.0T/A, ethylene loss is 112.0T/A in CN101747128B tail gas, and absorbent loss is 7.0T/A, tail gas of the present invention
In ethylene and adsorbent loss reduction, can be ignored.
From equipment, condenser built in CN101747128B domethanizing columns is a plate-fin heat exchanger, and of the invention
Segregation fractionating column be also to be developed to come by plate-fin heat exchanger, logistics side is filled with fractional distillation filling-material, and the two equipment investment differs
Less, it detaches consumption and cold energy use rate is as far apart as heaven and earth.
Claims (3)
1. a kind of system recycling ethylene from high propylene lighter hydrocarbons or preparing propylene from methanol product gas, including：First, second deethanization
Tower, drier, hydrogenation reactor, domethanizing column, domethanizing column tail gas recycle unit, ethylene rectifying column, it is characterised in that：
The domethanizing column tail gas recycle unit is made of combined absorbing tower, expanding machine and the second knockout drum；Combination absorbs
The top of tower is cryogenic rectification tower section, and lower part is to absorb tower section；
Drier and hydrogenation reactor are sequentially connected at the top of first dethanizer, hydrogenation reactor lower part connects domethanizing column；The
One Deethanizer bottom pipeline is divided into two, respectively connected the absorption tower section and depropanizing tower of combined absorbing tower；
Demethanizer overhead connects combined absorbing tower lower part, and expanding machine and the second gas-liquid separation are sequentially connected at the top of combined absorbing tower
Tank；Second knockout drum gas, liquid outlet line is respectively fed to the cryogenic rectification tower section of combined absorbing tower, and vapor delivery line is through depth
Recompression machine is connected after cold rectifying tower section to send out out-of-bounds；Liquid phase pipeline is sent out out-of-bounds after cryogenic rectification tower section；Combined absorbing tower
Bottom connects the first dethanizer top；
Demethanizer bottom connects the second dethanizer, and ethylene rectifying column, ethylene rectifying column side are connected at the top of the second dethanizer
Line sets side line outlet connection and takes off the second ethane tower；
Depropanizing tower outlet at bottom pipeline is divided into two, and one is sent out out-of-bounds, and one merges with the first Deethanizer bottom pipeline
The absorption tower section of combined absorbing tower is connected afterwards.
2. a kind of using the system for recycling ethylene from high propylene lighter hydrocarbons or preparing propylene from methanol product gas as described in claim 1
Method, it is characterised in that the method includes：
(1) product gas enters the first dethanizer, and the first deethanizer overhead gas products sequentially enter drier and add hydrogen anti-
Device is answered, enters domethanizing column after hydrogenated postcooling；First dethanizer bottom of tower fraction of stream is sent into the group of tail gas recycle unit
Absorption tower is closed as absorbent, rest part removes depropanizing tower；
(2) demethanizer column overhead tail gas recycles ethylene into tail gas recycle unit, and bottom of tower liquid phase is into the second dethanizer；Domethanizing column
Tail gas enters the absorption tower section of combined absorbing tower from bottom, and absorbent enters from the top for absorbing tower section, absorbs tower section bottom
Absorbent rich solution returns to the first dethanizer, and absorber portion top gas continues upwardly into the cryogenic rectification tower of combined absorbing tower
Section；Combined absorbing tower top gas phase passes through expansion, gas-liquid split-phase, and the deep cooling of combined absorbing tower is passed through in the logistics after split-phase respectively
After rectifying tower section re-heat, into subsequent handling；
(3) second deethanizer overhead gas phases obtain qualified ethylene product into ethylene rectifying column, and bottom of tower liquid phase is into propylene rectifying
Tower obtains qualified propylene product；Enter ethylene rectifying column after second deethanizer overhead gas throttling, from ethylene rectifying column side
Line extracts one liquid material out and is sent to the second deethanizer overhead, as the second deethanizer reflux；
(4) it goes as absorbent to combine absorption after depropanizing tower bottom of tower fraction of stream and the first Deethanizer bottom point logistics merge
Tower, remaining product are gone out-of-bounds.
3. the method for recycling ethylene from high propylene lighter hydrocarbons or preparing propylene from methanol product gas as claimed in claim 2, feature
It is：
First deethanizer overhead pressure is 2.8MPaG~3.2MPaG, and temperature is 13 DEG C~25 DEG C；
Demethanizer pressure on top surface is 2.4MPaG~3.0MPaG, and temperature is -35 DEG C.
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| CN108947755A (en) * | 2017-05-18 | 2018-12-07 | 朱琳 | A kind of system recycling separation of olefins tail gas pressure energy |
| KR102162297B1 (en) * | 2017-06-08 | 2020-10-06 | 주식회사 엘지화학 | Method and Apparatus of separating ethylene |
| CN110092701B (en) * | 2018-01-31 | 2023-08-15 | 中国寰球工程有限公司 | Light hydrocarbon separation method for MTO product mixed gas |
| CN110715505A (en) * | 2019-11-18 | 2020-01-21 | 汇智中科(北京)技术开发有限公司 | Device and method for recovering ethylene by cryogenic separation |
| CN111238164A (en) * | 2020-02-11 | 2020-06-05 | 大连理工大学 | Intercooling separation device and process for catalytic cracking product gas |
| CN114685236A (en) * | 2020-12-28 | 2022-07-01 | 中国石油化工股份有限公司 | Method and device for removing carbon dioxide and methanol from crude propylene gas |
| CN113943200A (en) * | 2021-11-15 | 2022-01-18 | 中安联合煤化有限责任公司 | Methanol-to-olefin light hydrocarbon recovery part cold separation unit and light hydrocarbon separation method thereof |
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