CN105439799A - System and method for recovering ethylene from high propylene light hydrocarbons or methanol-to-propylene product gas - Google Patents
System and method for recovering ethylene from high propylene light hydrocarbons or methanol-to-propylene product gas Download PDFInfo
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- CN105439799A CN105439799A CN201410410619.XA CN201410410619A CN105439799A CN 105439799 A CN105439799 A CN 105439799A CN 201410410619 A CN201410410619 A CN 201410410619A CN 105439799 A CN105439799 A CN 105439799A
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Abstract
The present invention discloses a system and a method for recovering ethylene from high propylene light hydrocarbons or a methanol-to-propylene product gas. The system comprises a first deethanizer, a second deethanizer, a dryer, a hydrogenation reactor, a demethanizer, a demethanizer tail gas recovery unit and an ethylene rectification column, the demethanizer tail gas recovery unit comprises a combination absorber, an expander and a second gas-liquid separation tank; the upper section of the combination absorber is a deep-cooling rectification column section, the lower part of the combination absorber is an absorber section. A front-end deethanization front-end hydrogenation, twin-tower deethanization and intercooling C3-C6 light hydrocarbon mixture absorbs demethanizer tail gas, an absorbent is from bottom products of the first deethanizer and a depropanizer, and the second deethanizer and the ethylene rectification column are directly thermally coupled. The system can increase ethylene recovery rate of the apparatus, and reduces the loss of the absorbent to further reduce energy consumption and investment of the section of recovery of the ethylene from the product gas.
Description
Technical field
The present invention relates to the low-carbon alkene field of refinement of high propylene content, say further, relate to a kind of system and method for recovered ethylene from high propylene lighter hydrocarbons or preparing propylene from methanol gas product.
Background technology
Ethene, propylene are the basic materials of petrochemical industry, and along with the scarcity of expanding economy, petroleum resources, the raw material such as petroleum naphtha, solar oil as ethylene production raw material faces more and more serious short situation.Along with the demand of ethene and propylene increases year by year, propylene/ethylene demand is than in rising trend, propylene/ethylene output ratio is on a declining curve, therefore, the low-carbon alkene production technology for the purpose of propylene enhancing such as catalytic pyrolysis (containing producing olefin hydrocarbon by catalytic pyrolysis CPP, Deep catalytic cracking DCC, olefins by catalytic cracking OCC, Superflex and ACO), methanol-to-olefins (MTO) or preparing propylene from methanol (MTP) is arisen at the historic moment, and has particularly opened up cheap propylene feedstocks source with technology such as coal based synthetic gas propylene, methane dehydrogenation coupling propylene.
The propylene and ethylene mass ratio (P/E) of these olefin producing technologies is usually more than 0.6, the P/E of MTO and MTP is then greater than 1, the wherein P/E>>1 of MTP, and the P/E of conventional vapor cracking ethylene preparation device is usually below 0.5.In conventional naphtha steam cracking gas, methane hydrogen richness is higher, generally adopts cryogenic method separation of methane and ethene.Deep cooling separating method all needs the Cryogenic Conditions of-100 DEG C, needs ethylene refrigeration compressor, even needs methane refrigeration compressor to provide cold for it.Device requires high to ice chest, and construction investment is strengthened, and energy consumption of compressor rises.
For the low-carbon alkene such as CPP, DCC, OCC, Superflex and ACO, MTO or MTP production technology, especially in the gas product such as coal based synthetic gas propylene, methane dehydrogenation coupling propylene, MTO and MTP, methane hydrogen richness is lower, propylene, ethylene content are high, the high-carbon hydrocarbon content of carbon more than six is less, and the cold that demethanizing tower needs is relatively little.
US7714180 proposes a kind of processing method of olefin recovery.According to the method, first gas product removes C through debutanizing tower after compression
5 +heavy constituent, from tower top C out
4light constituent compresses further again, successively enters demethanizing tower, deethanizing column, depropanizing tower after cooling, and mixed c 4 at the bottom of depropanizing tower tower makees the ethene that absorption agent goes in the top gas of demethanizing tower absorption tower, improves Recovery rate of ethylene.
This invention is avoided adopting deep cooling process for separating, but adopts oily absorption technique, reduces investment.But use mixed c 4 absorption agent internal circulating load large and long flow path, energy consumption is large.If time in carbon four containing more divinyl, downstream relevant device coking can be made serious.
Chinese patent 200810201217.3 proposes the separation method of lighter hydrocarbons in a kind of MTO/MTP gas product.According to the method, after light hydrocarbon product pre-treatment, directly enter deethanizing column, tower top C
2light constituent enters absorption tower again, makees absorption agent with ethane, to improve Recovery rate of ethylene.Employing The method avoids use ethylene refrigeration compressor, ethane is adopted to make absorption agent, part ethane loses from absorption tower tower top and makes fuel gas, but when the ethane that reaction process produces is less than the ethane of absorption tower loss, uses ethane to make absorption agent just improper.
CN101973831A has invented a kind of low-carbon alkene separation method.What adopt is predepropanization separation process.Depropanizing tower tower top C
3light constituent enters demethanizing tower after compressing cooling further, and the very useful ethane of demethanizer makees absorption agent, to improve the rate of recovery of ethene.Carbon two ~ carbon three at the bottom of demethanizer goes deethanizing column to carry out being separated of carbon two and carbon three, carbon two enters ethylene rectification tower, side take-off ethene, tower top non-condensable gas returns compressor, as demethanizing tower absorption agent or partly as fuel gas extraction after ethane at the bottom of tower all cools.Carbon three removes propylene rectification tower, overhead extraction propylene, and at the bottom of tower, extraction propane does LPG byproduct.Consider that the ethane amount that some reaction process produces is less, this patent is taken out part propane and is done supplementing of ethane absorption agent at the bottom of propylene tower tower.
Because using ethane to make absorption agent, in demethanizer column overhead tail gas, ethane content is more than 20%.The dilution to ethylene column and propylene tower input concentration of the longer on stream circulating path of absorption agent, absorption agent both increases the energy consumption of device.
When making absorption agent with ethane, in the tower top tail gas of absorption tower, ethane content is very high, and cycle ethane is often carried out steam cracking by large-scale MTO/MTP device, will take into full account recycling and the tail gas loss problem of ethane when making absorption agent with ethane.
CN100398498C discloses the separation method of a kind of converting methanol to prepare low carbon olefin (DMTO) gas, the most conventional front-end deethanization separation process, improves the flow process after four sections of compressions.According to this invention, between five sections of compressions and deethanizer reflux tank, design hydrocracking, remove the oxide compound produced in acetylene and reaction regeneration process, the logistics after condensing cooling is through deethanizer reflux tank, liquid phase is as deethanizer reflux, and gas phase enters deep cooling demethanizing tower.
CN101353286A proposes a kind of non-copious cooling lower carbon number hydrocarbons separation method.The method delivers to precut tower (demethanizing tower) after pretreated reactor outlet gas is cooled to 10 DEG C ~-37 DEG C.Precut column overhead cools laggard absorption tower containing the tail gas of methane hydrogen, carbon two and a small amount of carbon three, with the absorption agent that the mixture of carbon three, carbon four, carbon five and hydro carbons forms, the C2 hydrocarbon class in precut tower overhead is absorbed, light gas is discharged by top, and absorption tower bottom product returns precut tower (demethanizing tower); The product of precut tower (demethanizing tower) tower reactor carbon containing two and more heavy constituent enters deethanizing column and carries out carbon two and carbon three cleaning cutting, and tower top obtains C-2-fraction; Tower reactor obtains carbon three and more heavy constituent.This patent precut column overhead tail gas and absorption agent all need with the cooling of ethene cryogen, and a large amount of absorption agents in tail gas can not efficient recovery, is burnt in vain.This patent is only applicable to the technique of gas product propylene and ethylene mass ratio (P/E)≤P, as methanol-to-olefins (MTO), be not suitable for this P/E>>1 olefin process of preparing propylene from methanol (MTP).
CN202081036U has invented a kind of method that MTP gas product lighter hydrocarbons are separated, and this patent adopts predepropanization process.After gas product two sections compression, enter the 3rd section, compressor compress through washing, alkali cleaning, the gas product after compression is through cohesion, dry laggard depropanizing tower.Condensed liquid stripping tower is provided with, for separating of the lighter hydrocarbons in lime set between compressor section between compressor section.The light hydrocarbon gas at condensate stripper top returns compressor two sections of entrances, and the heavy hydrocarbon at the bottom of tower delivers to debutanizing tower.Depropanizing tower is located between three sections and four sections, compressor, and adopts conventional rectification; Depropanizing tower top gaseous phase product is through the laggard deethanizing column of four sections, compressor compression, and bottom product carbon elimination four circulates; Deethanizer overhead product enters demethanizing tower, and bottom product enters propylene rectification tower; Demethanizer column overhead lays tail gas supercooler, and reclaim self cold by throttling refrigeration mode and reduce ethylene loss, bottom product enters ethylene rectification tower.This patent has continued the mentality of designing of traditional MTP device substantially, and demethanizer column overhead adopts ethene cryogen, and plant energy consumption problem does not obtain too large improvement.
CN101747128B discloses a kind of separation method of methane low carbon olefin gas, to solve the shortcoming that in prior art, in demethanizing overhead gas, ethylene loss is large.The feature of this patent arranges decompressor at demethanizing tower top, built-in cold condenser is set in demethanizing tower, gaseous stream in demethanizing tower,-45 DEG C ~-60 DEG C are cooled to through built-in cold condenser, decompressor is entered from demethanizer column overhead gas phase out, temperature is crossed and is as cold as-90 DEG C ~-120 DEG C, pressure drops to 0.1MPaG ~ 0.6MPaG, gas-liquid separation is carried out in the logistics going out decompressor, wherein go out battery limit (BL) after gas stream re-heat, liquid phase stream air inlet gas compressor the first two section of suction tank, or return demethanizing tower, demethanizing tower bottoms stream enters other separation of olefins unit and isolates ethene and propylene product, described demethanizing tower absorption agent is C3, more than one materials in C4 and C5+ cut.
The built-in condenser of demethanizing tower in this patent is actually the segregative dephlegmator (Dephlegmator) that ethylene unit is often mentioned, and often runs into ethylene content in tail gas and exceed standard phenomenon during similar techniques practical application.
CN102476976A has invented a kind of method that absorption extraction reclaims lighter hydrocarbons, and this patent adopts front-end deethanization flow process, uses C
3h
6, C
4or C5 liquid hydrocarbon makes absorption agent, reclaim the ethene in demethanizing tower tail gas, the absorption agent rich solution at the bottom of absorption tower returns front-end deethanization tower and carries out desorb.This patent does not do further statement to the alkene in tail gas from absorption tower and absorption agent recovery method.
The quality of low-carbon alkene separation method is mainly reflected in energy consumption, product recovery rate and synthetic analysis three aspects, especially product recovery rate and energy consumption.Mainly there is demethanizing tower, ethylene rectification tower in low-carbon alkene sepn process ethylene loss, and demethanizing tower system ethylene loss accounts for more than 60% of olefin separation system ethylene loss, the energy consumption reduction of demethanizing tower system plays vital effect to plant energy consumption reduction.
A lot of patent all claims that absorption agent can be carbon four or carbon five, but in the specific implementation, carbon four or carbon five absorption agent are from the depropanizing tower after flow process or debutanizing tower, rich absorbent at the bottom of absorbing tower needs just can complete reprocessing cycle through two or three towers, need repeatedly to boil and condensation, facility investment and energy consumption are all uneconomical again.
Indivedual patent proposes methanol-to-olefins device demethanizing tower tail gas and low-temperature expansion can be utilized to reclaim, and the tail gas recycle technology be made up of ice chest, decompressor of these patents regulation with conventional ethylene device demethanizing tower tail gas expansion condensation technology relatively, cryogenic energy utilization rate is not high.
Be necessary to find high propylene lighter hydrocarbons or preparing propylene from methanol (MTP) gas product ethylene recovery technology targetedly.
Summary of the invention
For solving produced problem in prior art, the invention provides a kind of system and method for recovered ethylene from high propylene lighter hydrocarbons or preparing propylene from methanol gas product.Device Recovery rate of ethylene can be improved, reduce absorption agent loss, reduce energy consumption and the investment of gas product ethylene recovery part further.
An object of the present invention is to provide a kind of system of recovered ethylene from high propylene lighter hydrocarbons or preparing propylene from methanol gas product.
Comprise: first, second deethanizing column, moisture eliminator, hydrogenator, demethanizing tower, demethanizing tower tail gas recycle unit, ethylene rectification tower,
Described demethanizing tower tail gas recycle unit is made up of combined absorbing tower, decompressor and the second knockout drum; The top of combined absorbing tower is cryogenic rectification tower section, and bottom is absorption tower section;
First deethanizing column top connects moisture eliminator and hydrogenator successively, and hydrogenator bottom connects demethanizing tower; First Deethanizer bottom pipeline is divided into two, respectively connected absorption tower section and the depropanizing tower of combined absorbing tower;
Demethanizer overhead connects combined absorbing tower bottom, and combined absorbing tower top connects decompressor and the second knockout drum successively; The cryogenic rectification tower section of combined absorbing tower sent into respectively by second knockout drum gas, liquid outlet line, and vapor delivery line connects recompression machine and sends out-of-bounds after cryogenic rectification tower section; Liquid phase pipeline is sent out-of-bounds after cryogenic rectification tower section; The first deethanizing column top is connected bottom combined absorbing tower;
Demethanizer bottom connects the second deethanizing column, and the second deethanizing column top connects ethylene rectification tower, and ethylene rectification tower side line establishes side line to export de-second ethane tower of connection;
Depropanizing tower outlet at bottom pipeline is divided into two, sends out-of-bounds for one, and one merges the rear absorption tower section being connected combined absorbing tower with the first Deethanizer bottom pipeline.
Two of object of the present invention is to provide a kind of method of recovered ethylene from high propylene lighter hydrocarbons or preparing propylene from methanol gas product.
Comprise:
(1) gas product enters the first deethanizing column, and the first deethanizer overhead gas products enters moisture eliminator and hydrogenator successively, after hydrogenation, enter demethanizing tower after cooling; The combined absorbing tower that first deethanizing column tower bottom divides logistics to send into tail gas recycle unit is as absorption agent, and rest part removes depropanizing tower;
(2) demethanizer column overhead tail gas enters tail gas recycle unit recovered ethylene, and liquid phase at the bottom of tower enters the second deethanizing column;
(3) second deethanizer overhead gas phases are entered ethylene rectification tower and are obtained qualified ethylene product, and liquid phase at the bottom of tower is entered propylene rectification tower and obtained qualified propylene product;
(4) point logistics of depropanizing tower tower bottom and point logistics of the first Deethanizer bottom remove combined absorbing tower as absorption agent after merging, and all the other products go out-of-bounds.
Wherein,
In step (2), demethanizing tower tail gas enters the absorption tower section of combined absorbing tower from bottom, absorption agent enters from the top of absorption tower section, absorption agent rich solution bottom the section of absorption tower returns the first deethanizing column, and absorber portion top gas continues the cryogenic rectification tower section upwards entering combined absorbing tower;
Combined absorbing tower top gas phase is through overexpansion, gas-liquid phase-splitting, and the logistics after phase-splitting, after the cryogenic rectification tower section re-heat of combined absorbing tower, enters subsequent handling.
Enter ethylene rectification tower after second deethanizer overhead gas throttling, deliver to the second deethanizer overhead, as the second deethanizer reflux from one liquid material of ethylene rectification tower lateral line withdrawal function.
In the present invention, the processing condition of each equipment can adopt common operational condition in prior art, and those skilled in the art can adjust according to practical situation.
In the present invention, can be preferred:
First deethanizer overhead preferred operations pressure is 2.8MPaG ~ 3.2MPaG, and preferred operations temperature is 13 DEG C ~ 25 DEG C;
Demethanizer column overhead preferred operations pressure is 2.4MPaG ~ 3.0MPaG, and preferred operations temperature is-35 DEG C.
The present invention specifically can by the following technical solutions:
Comprise: the first deethanizing column, depropanizing tower, moisture eliminator, hydrogenator, demethanizing tower, demethanizing tower tail gas recycle unit, " coupling " second integrated deethanizing column of heat and ethylene rectification tower.
1 double tower deethanizing of the present invention:
Gas product through overdraft, purification enters the first deethanizing column, the preferred 2.8MPaG ~ 3.2MPaG of the first deethanizer overhead pressure.First deethanizer overhead gas, successively through drying unit and hydrogenation unit, enters demethanizing tower after the gas product cooling after hydrogenation.Demethanizer column overhead tail gas enters exhaust gas recovery system recovered ethylene, and its bottom product enters the second deethanizing column.
First deethanizing column part bottom product removes demethanizing tower tail gas recycle unit as absorption agent, and rest part removes depropanizing tower.
2 tail gas recycle unit are made up of combined absorbing tower, decompressor and the second knockout drum.
(1) the cryogenic rectification tower section of-35 DEG C ~-108 DEG C that to be preferred working temperature be on combined absorbing tower top, bottom is absorption 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, then upwards enters cryogenic rectification tower section, and the logistics of cryogenic rectification tower section bottom liquid phases, as a part for absorber portion absorption agent, relies on flow by gravity to section top, absorption tower.Preferable temperature pressure is-99 DEG C ~-108 DEG C, the cryogenic rectification tower section top gas of 2.5MPaG out after freeze through expander, the material going out decompressor enters knockout drum and carries out gas-liquid separation, the liquid phase separated carries out re-heat respectively through cryogenic rectification tower section, 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 remove propylene rectification tower, and tower bottom divides product to remove demethanizing tower tail gas recycle unit as absorption agent, and all the other products go out-of-bounds.
4 absorption agents of the present invention are be rich in C3 ~ C6 liquid hydrocarbon mixture from the bottom of the first deethanizing column tower first, are be rich in C4 ~ C6 liquid hydrocarbon mixture from the bottom of depropanizing tower tower in addition.
Described in 5 inventions " coupling " integrated the second deethanizing column of heat and ethylene rectification tower, its principal character is: the second deethanizing column and ethylene rectification tower adopt " thermal coupling " form combination, second deethanizing column does not establish overhead condenser and return tank, and employing is pumped into the second deethanizer overhead from one liquid material of ethylene rectification tower lateral line withdrawal function, as the second deethanizer reflux.
The method concrete steps of 6 recovered ethylene from high propylene lighter hydrocarbons or preparing propylene from methanol (MTP) gas product of the present invention comprise.
(1) after the gas product cooling of pre-treatment, boosting, the first deethanizing column is entered, top gaseous phase product is respectively through dry and hydrogenation reaction, demethanizing tower after hydrogenator logistics cooling out, tower bottom divides liquid-phase product to remove demethanizing tower tail gas recycle unit as absorption agent, and rest part removes depropanizing tower.
(2) demethanizer column overhead tail gas enters demethanizing tower exhaust gas recovery system continuation recovered ethylene and absorption agent, and demethanizing tower bottom product removes the second deethanizing column.
(3) demethanizer column overhead tail gas enters the absorption tower section of combined absorbing tower from bottom, gas continues the cryogenic rectification tower section going upward to combined absorbing tower top in absorber portion, cryogenic rectification tower section bottom liquid phases material is as a part for absorption tower section absorption agent, flow automatically to top, absorption tower, cryogenic rectification section tail gas then directly enters into expander refrigeration.
Absorption liquid enters combined absorbing tower from section top, absorption tower, laggard first deethanizing column of absorption agent rich solution re-heat out at the bottom of combined absorbing tower tower.
(4) from combined absorbing tower cryogenic rectification tower section top tail gas out, this tail gas is through swell refrigeration, the material going out decompressor enters knockout drum and carries out gas-liquid separation, the liquid phase separated is respectively through the re-heat of cryogenic rectification tower section, gas phase after re-heat goes fuel gas system after the boosting of recompression machine, and the liquid phase after re-heat removes gas product compressor three sections of suction tanks.
(5) second deethanizing columns and ethylene rectification tower adopt " coupling " hot integration mode combination, and the second deethanizing column does not arrange overhead condenser and return tank.The laggard ethylene rectification tower of second deethanizer overhead gas phase reducing pressure by regulating flow, obtain qualified ethylene product, ethylene rectification tower tower top pressure is not less than 1.651MPaG.The second deethanizer overhead is pumped into, as the second deethanizer reflux from one liquid material of ethylene rectification tower lateral line withdrawal function.
(6) depropanizing tower overhead product removes propylene rectification tower, and tower bottom divides product to remove demethanizing tower tail gas recycle unit, outside rest part out-of-bounds as absorption agent.
System and method of the present invention is applicable to the full scale plant that all richnesses produce low-carbon alkene, as methanol-to-olefins (MTO) device, Methanol aromatic hydrocarbons (MTA) device, methane dehydrogenation coupling propylene or coal based synthetic gas propylene unit, be preferably applied to MTP device.
The present invention and prior art contrast have the superiority of several aspect:
(1) adopt the demethanizing tower exhaust gas recovery system of combined absorbing tower, decompressor and ice chest composition, effectively can reduce the loss of ethene and absorption agent in tail gas, improve utilization ratio and the yield of ethene of cryogenic energy.
(2) the present invention adopts front-end deethanization front-end hydrogenation, double tower deethanizing technology, absorption agent is made with C4 ~ C6 hydrocarbon mixture at the bottom of C3 ~ C6 hydrocarbon mixture at the bottom of the first deethanizing column tower and depropanizing tower tower, absorption agent rich solution returns the first deethanizing column, improves the processing property of demethanizing tower.
Absorption agent circulation process is shorter, and molecular weight is large, makes relative unit size become less.
(3) at the bottom of the combined absorbing tower tower that proposes of the present invention, absorption agent rich solution out returns the first deethanizing column, is particularly useful for the Special Circumstances of this P/E>>1 of MTP.
(4) the present invention is by the second deethanizing column and ethylene column " thermal coupling " integrate, reduce the consumption of system cryogen.
The present invention improves mainly for recovered ethylene and demethanizing tower system from the MTP gas product of P/E>>1, be applicable to other rich full scale plants producing high propylene content low carbon olefin gas too, as producing olefin hydrocarbon by catalytic pyrolysis CPP, Deep catalytic cracking DCC, olefins by catalytic cracking OCC, Superflex, ACO etc.
Accompanying drawing explanation
The system flowchart of Fig. 1 recovered ethylene from MTP gas product of the present invention.
Description of reference numerals:
Device flag illustrates:
1-first deethanizing column, 2-moisture eliminator, 3-hydrogenator, 4 knockout drums ,-demethanizing tower, 6-demethanizing tower built-in plate-fins condenser (or built-in CFT), 7--combined absorbing tower, 8-absorption tower section, 9-cryogenic rectification tower section, 10-second knockout drum, 11-decompressor, 12-recompress machine, 13-second deethanizing column, 14-ethylene rectification tower, 15-depropanizing tower.
Logistics description of symbols:
100-gas product, the expander outlet liquid phase after 102-re-heat, 103-recompresses the tail gas of machine outlet, the ethylene product that 104-is qualified, 105-ethane product, 106-second deethanizing column bottom product, 107-depropanizing tower overhead product, 108-depropanizing tower bottom product, 109-absorption agent.
Embodiment
Below in conjunction with embodiment, further illustrate the present invention.
Embodiment:
As shown in Figure 1, a kind of system of recovered ethylene from high propylene lighter hydrocarbons or preparing propylene from methanol gas product.
Comprise: the first deethanizing column 1, depropanizing tower 15, moisture eliminator 2, hydrogenator 3, demethanizing tower 5, demethanizing tower tail gas recycle unit, the second deethanizing column 13 and ethylene rectification tower 14;
Described tail gas recycle unit is made up of combined absorbing tower 7, decompressor 11 and the second knockout drum 10; The top of combined absorbing tower 7 is cryogenic rectification tower sections 9, and bottom is absorption tower section 8;
First deethanizing column 1 top connects hydrogenator 3 after connecting moisture eliminator 2 again, and hydrogenator 3 bottom connects knockout drum 4, and knockout drum 4 connects demethanizing tower 5;
First deethanizing column 1 bottom line is divided into two, connects the absorption tower section 8 of depropanizing tower 15 and combined absorbing tower 7 respectively; Demethanizing tower 5 top connects combined absorbing tower 7 bottom, and combined absorbing tower 7 tower top connects decompressor 11, and decompressor 11 exports connection second knockout drum 10; The cryogenic rectification tower section 9 of combined absorbing tower 7 sent into respectively by second knockout drum 10 gas, liquid outlet line, and vapor delivery line connects recompression machine 12 and sends out-of-bounds after cryogenic rectification tower section; Liquid phase pipeline is sent out-of-bounds after cryogenic rectification tower section;
Connect the second deethanizing column 13, second deethanizing column 13 top bottom demethanizing tower 5 and connect ethylene rectification tower 14, ethylene rectification tower 14 side line arranges outlet, side line outlet connection second deethanizing column 13.
Remove combined absorbing tower 7 as absorption agent after point logistics of depropanizing tower 15 tower bottom mixes with the first Deethanizer bottom logistics, rest part goes out-of-bounds.
In high propylene lighter hydrocarbons or preparing propylene from methanol gas product, the method for recovered ethylene comprises:
(1) after washing, compression, alkali cleaning, the cooling of removing impurities matter gas product 100, the first deethanizing column 1 is entered.
Return tank 4 is entered after going hydrogenator 3 hydrogenation to remove limited diolefine and alkynes, cooling after (2) first deethanizing column 1 top gas phase product drying device 2 dryings.Return tank 4 top and the liquid phase of bottom enter demethanizing tower 5 respectively and realize being separated of carbon one and the second-class heavy constituent mixture of carbon.
A first deethanizing column 1 bottom product part removes combined absorbing tower 7 as absorption agent, and rest part enters depropanizing tower 15.
(3) depropanizing tower 15 tower bottom divides product to remove combined absorbing tower 7 as absorption agent, and rest part goes out-of-bounds.
(4) working temperature of the built-in condenser 6 of demethanizing tower 5 tower top is-35 DEG C, and tower top tail gas directly enters the bottom recovered ethylene of combined absorbing tower 7, and liquid phase at the bottom of demethanizer removes the second deethanizing column 13.
(5) for demethanizing tower tail gas recycle unit:
Combined absorbing tower 7 absorber portion 8 top exit is directly ined succession cryogenic rectification tower section 9, demethanizing tower tail gas 4 enters absorption tower section 8 from bottom, cryogenic rectification tower section 9 is entered again from the top of absorption tower section 8, cryogenic rectification tower section 9 technique side bottom liquid phase relies on gravity to return to the top of absorption tower section 8, and the non-condensable gas at cryogenic rectification tower section 9 top enters the second knockout drum 10 after decompressor 11 swell refrigeration.
Go fuel gas system through the re-heat of cryogenic rectification tower section 9, recompression machine 12 boosting after second knockout drum 10 top non-condensable gas 103 throttling, the second knockout drum 10 bottom liquid is through laggard first deethanizing column 1 of cryogenic rectification tower section 9 re-heat.
Absorption liquid 109 from the first Deethanizer bottom enters the top of combined absorbing tower 7 absorption tower section 8, and returns the first deethanizing column 1 at the bottom of combined absorbing tower 7 tower.
(6) second deethanizing column 13 top gaseous phase product introduction ethylene rectification towers 14 obtain qualified ethylene product 104, simultaneously extract one liquid phase out from ethylene rectification tower 14 to return liquid-phase product 106 at the bottom of the second deethanizing column 13, second deethanizing column 13 tower as phegma and enter propylene rectification tower and obtain qualified propylene product.
First deethanizing column charging 100 forms in table 1.
Table 1
Adopt the Provision7.0 process simulation software of general Simsci company, the flow scheme of the present embodiment is simulated, obtain the analog calculation result shown in table 2.
Calculation result shows, adopts method of the present invention to be separated MTP gas product, from reactor give up pot outlet gas product to qualified ethylene product, Recovery rate of ethylene is 99.64%.
Key stream composition is in table 2.
Table 2
Comparative example 1
Based on the charging of embodiment 1 first deethanizing column, adopt the ethene in the technical scheme recovery tail gas of patent CN101353286A.The loss of ethene and absorption agent, in table 3.
Comparative example 2
Based on the charging of embodiment 1 first deethanizing column, adopt the ethene in the technical scheme recovery tail gas of patent CN101747128B.The loss of ethene and absorption agent, in table 3.
Table 3
As can be seen from Table 3, in CN101353286A tail gas, ethylene loss is 120.0T/A, absorption agent (C4 ~ C6) loss is 912.0T/A, in CN101747128B tail gas, ethylene loss is 112.0T/A, absorption agent loss is 7.0T/A, ethene in tail gas of the present invention and sorbent material loss reduction, negligible.
Slave unit is seen, the built-in condenser of CN101747128B demethanizing tower is a plate-fin heat exchanger, and segregation fractionating column of the present invention is also developed by plate-fin heat exchanger, logistics side is filled with fractional distillation filling-material, both facility investments is more or less the same, and separation consumes and cold energy use rate as far apart as heaven and earth.
Claims (5)
1. the system of recovered ethylene from high propylene lighter hydrocarbons or preparing propylene from methanol gas product, comprising: first, second deethanizing column, moisture eliminator, hydrogenator, demethanizing tower, demethanizing tower tail gas recycle unit, ethylene rectification tower, is characterized in that:
Described demethanizing tower tail gas recycle unit is made up of combined absorbing tower, decompressor and the second knockout drum; The top of combined absorbing tower is cryogenic rectification tower section, and bottom is absorption tower section;
First deethanizing column top connects moisture eliminator and hydrogenator successively, and hydrogenator bottom connects demethanizing tower; First Deethanizer bottom pipeline is divided into two, respectively connected absorption tower section and the depropanizing tower of combined absorbing tower;
Demethanizer overhead connects combined absorbing tower bottom, and combined absorbing tower top connects decompressor and the second knockout drum successively; The cryogenic rectification tower section of combined absorbing tower sent into respectively by second knockout drum gas, liquid outlet line, and vapor delivery line connects recompression machine and sends out-of-bounds after cryogenic rectification tower section; Liquid phase pipeline is sent out-of-bounds after cryogenic rectification tower section; The first deethanizing column top is connected bottom combined absorbing tower;
Demethanizer bottom connects the second deethanizing column, and the second deethanizing column top connects ethylene rectification tower, and ethylene rectification tower side line establishes side line to export de-second ethane tower of connection;
Depropanizing tower outlet at bottom pipeline is divided into two, sends out-of-bounds for one, and one merges the rear absorption tower section being connected combined absorbing tower with the first Deethanizer bottom pipeline.
2. adopt a method for the system of recovered ethylene from high propylene lighter hydrocarbons or preparing propylene from methanol gas product as claimed in claim 1, it is characterized in that described method comprises:
(1) gas product enters the first deethanizing column, and the first deethanizer overhead gas products enters moisture eliminator and hydrogenator successively, after hydrogenation, enter demethanizing tower after cooling; The combined absorbing tower that first deethanizing column tower bottom divides logistics to send into tail gas recycle unit is as absorption agent, and rest part removes depropanizing tower;
(2) demethanizer column overhead tail gas enters tail gas recycle unit recovered ethylene, and liquid phase at the bottom of tower enters the second deethanizing column;
(3) second deethanizer overhead gas phases are entered ethylene rectification tower and are obtained qualified ethylene product, and liquid phase at the bottom of tower is entered propylene rectification tower and obtained qualified propylene product;
(4) point logistics of depropanizing tower tower bottom and point logistics of the first Deethanizer bottom remove combined absorbing tower as absorption agent after merging, and all the other products go out-of-bounds.
3. the method for recovered ethylene from high propylene lighter hydrocarbons or preparing propylene from methanol gas product as claimed in claim 2, is characterized in that:
In step (2), demethanizing tower tail gas enters the absorption tower section of combined absorbing tower from bottom, absorption agent enters from the top of absorption tower section, absorption agent rich solution bottom the section of absorption tower returns the first deethanizing column, and absorber portion top gas continues the cryogenic rectification tower section upwards entering combined absorbing tower;
Combined absorbing tower top gas phase is through overexpansion, gas-liquid phase-splitting, and the logistics after phase-splitting, after the cryogenic rectification tower section re-heat of combined absorbing tower, enters subsequent handling.
4. the method for recovered ethylene from high propylene lighter hydrocarbons or preparing propylene from methanol gas product as claimed in claim 3, is characterized in that:
Enter ethylene rectification tower after second deethanizer overhead gas throttling, deliver to the second deethanizer overhead, as the second deethanizer reflux from one liquid material of ethylene rectification tower lateral line withdrawal function.
5. the method for recovered ethylene from high propylene lighter hydrocarbons or preparing propylene from methanol gas product as described in one of claim 2 ~ 4, is characterized in that:
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 |
| CN110092701A (en) * | 2018-01-31 | 2019-08-06 | 中国寰球工程有限公司 | The lighter hydrocarbons separation system and method for MTO product mix gas |
| CN110621645A (en) * | 2017-06-08 | 2019-12-27 | 株式会社Lg化学 | Ethylene separation process and separation apparatus |
| 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 |
| 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 |
| 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 |
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| 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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