CN202898270U - System for recycling ethylene from tail gas during demethanization by barren liquor effect - Google Patents
System for recycling ethylene from tail gas during demethanization by barren liquor effect Download PDFInfo
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- CN202898270U CN202898270U CN 201220613994 CN201220613994U CN202898270U CN 202898270 U CN202898270 U CN 202898270U CN 201220613994 CN201220613994 CN 201220613994 CN 201220613994 U CN201220613994 U CN 201220613994U CN 202898270 U CN202898270 U CN 202898270U
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Abstract
The utility model relates to a system for recycling ethylene from tail gas during demethanization by a barren liquor effect. According to the system, an absorption tower is matched with separation devices of all stages of a front-end quenching series, almost all hydrogen gas and part of methane are separated from a feed, and the rest methane and almost all C2<+> are enabled to enter a fractionating tower for fractionation. During the process, due to the characteristic that an absorbent of the absorption tower preferentially dissolves the C2<+>, ethylene which is possibly lost in the tail gas can be recycled more completely. The absorbent of the absorption tower is barren liquor from the inside of the system, namely part of reflux liquid of the fractionating tower, so that the barren liquor effect is embodied. Compared with the prior art that the stages of the front-end quenching series are changed with fractionation subsystems with multiple theoretical plates, the system has the advantages that the effect of loss control on the ethylene in the tail gas is better, the energy consumption is lower, and the investment is smaller.
Description
Technical field
The utility model relates to a kind of lighter hydrocarbons separation system, particularly relates to the system that reclaims ethene in the tail gas with the lean solution effect in the demethanizing process.
Background technology
Lighter hydrocarbons separate, refer to the related production device such as ethylene unit to the hydrogen of its recovery and carbon one to the (abbreviation: H of carbon five hydrocarbon mixtures
2-C
1-C
5) separation carried out.
Hydrogen and methane miscellany are abbreviated as C
1 -, carbon one reaches more last running and is abbreviated as C
1 +, C-2-fraction is abbreviated as C
2, hydrogen be abbreviated as H separating of methane
2/ CH
4Separate C
1 -With C
2 +Separation be abbreviated as C
1 -/ C
2 +Separate C
1 -With C
2Separation be abbreviated as C
1 -/ C
2Separate.
C in the lighter hydrocarbons separating technology
1 -/ C
2 +Separate or C
1 -/ C
2Separate and also claim " demethanizing ".Demethanizing needs to finish through two allo systems usually, and one is front end Quench series (being called for short " front cold "), and another is demethanizing tower system.Before coldly usually combined by a plurality of charging separating devices and many platens fin heat exchanger, each charging separating device is called front one cold " level ".Charging at first enters front cold.Before cold to charging cool off step by step, condensation, flash distillation, with hydrogen and a part of methane and another part methane and whole C almost
2 +Cut separately.This step can be described as " preliminary " demethanizing.Before the gas phase discharging of cold final stage separating device be that hydrogen and a part of methane (the utility model alleged " tail gas ") are conveyed to and carry out H
2/ CH
4Separate.Comprise the liquid phase discharging of the separating devices at different levels of final stage, i.e. another part methane and almost whole C
2 +Cut is sent to demethanizing tower system and carries out " final " demethanizing.
Front cold effect is equivalent to the separation column of a horizontal positioned, and each " level " is equivalent to a theoretical stage of separation column." level " number is more, and the number of theoretical plate of " tower " is just more, and the energy consumption that reaches same separation requirement is just lower.Here " separation requirement " refers to, and the ethene quantity that is lost in the tail gas is controlled in the high as far as possible zone of reasonableness of efficiency-cost ratio.Because the refrigerant temperature level limited bits that propylene, ethene cascade refrigeration can provide, front cold " level " digital display so can not be too many." level " number too much will cause investing excessive, and system is too complicated, be difficult to realize in engineering practice.
Under the limited conditions of front cold " level " number, it is often higher and can not be satisfactory to be lost in the tail gas ethene quantity.How could when reaching the control ethylene loss target of expection, make energy consumption also lower? only manage to reclaim the ethene of possible loss in tail gas.For this reason, the way of prior art is originally to be equivalent to a few " levels " or end one " level " of a theoretical stage, and to become the fractionation subsystem with polylith theoretical stage.Concrete pattern has two kinds:
-replace certain several " levels " with segregative dephlegmator (a kind of clustered aggregates with heat transfer, mass transfer dual-use function);
-with tail gas rectifying tower (containing return tank etc.), replace final stage charging separating tank.
The first way is too high because of investment, promotes limited to Engineering Market; The second way is identical with the first way principle, and is also energy-conservation because having increased whole front cold theoretical plate number, though investment is lower but still higher than the first way, energy-saving effect is not remarkable.
The utility model content
The technical problems to be solved in the utility model is: for the demethanizing process provides a kind of separation system with ethene in the lean solution effect recovery tail gas, only increase small investment, just can realize more significant energy-saving effect in the ethylene loss in control tail gas.The utility model is applicable to lighter hydrocarbons and separates all types of demethanizing processes.
So-called " lean solution effect " refers to: often can have such two strands of materials in the lighter hydrocarbons sepn process: the content of certain easily dissolved component in one gaseous phase materials (normally purpose product) is higher, is called " rich gas "; The content of this easily dissolved component is lower in another strand liquid phase material, is called " lean solution ".If manage to allow lean solution contact with rich gas, this easily dissolved component in the rich gas will be absorbed by lean solution, and therefore lean solution becomes " rich solution ".Like this, may just can reduce with this easily dissolved component that rich gas is overflowed and be recycled in the rich solution, rich gas also is able to purifying because of this easily dissolved component content.Lean solution has absorbed more easily dissolved component and after becoming rich solution, has not needed as typical absorption process, and ad hoc desorption tower becomes lean solution again to it, and only need give it to enter the downstream separation column, carries out fractionation with other charging of this separation column.Therefore this easily dissolved component is recycled in the materials at bottom of tower of this tower, and this column overhead overhead product that has removed this easily dissolved component is lean solution.Therefrom tell one, allow it be circulated back to the absorption tower as absorption agent, again absorb easily dissolved component, again become rich solution and enter the downstream separation column.So move in circles, can when reclaiming this easily dissolved component, reducing its loss, reduce energy consumption.
The utility model a kind of " in the demethanizing process, reclaiming the system of ethene in the tail gas with the lean solution effect ".Native system comprises front cold, demethanizing gas stripping column, demethanizing rectifying tower, carbon two absorption towers, demethanizing tower return tank, demethanizing rectifying tower condenser, expansion-recompression machine.Front cold many demethanizing tower feed exchangers (preferred plate-fin heat exchanger) and many demethanizing tower charging separating tanks of containing wherein.
The combined feed total feed pipeline is communicated with the opening for feed of the first demethanizing tower charging separating tank by a demethanizing tower feed exchanger, introduces feeding gas.Described combined feed total feed pipeline also is communicated with the opening for feed of the first demethanizing tower charging separating tank by relevant interchanger such as demethanizing gas stripping column reboilers, introduces feeding gas.
The air outlet, top of the first demethanizing tower charging separating tank is communicated with the second demethanizing tower charging separating tank opening for feed by No. two demethanizing tower feed exchangers, the air outlet, top of the second demethanizing tower charging separating tank is communicated with the 3rd demethanizing tower charging separating tank opening for feed by No. three demethanizing tower feed exchangers, and the air outlet, top of the 3rd demethanizing tower charging separating tank is communicated with the downside opening for feed on carbon two absorption towers by No. four demethanizing tower feed exchangers.The bottom discharge port of first, second, third demethanizing tower charging separating tank is communicated with three opening for feeds of demethanizing gas stripping column respectively.
The air outlet, top on carbon two absorption towers is communicated with native system methane, hydrogen interchanger inlet mouth outward, and its bottom liquid outlet is communicated with the upside opening for feed of demethanizing rectifying tower.
The air outlet, top of demethanizing gas stripping column is communicated with the downside opening for feed of demethanizing rectifying tower by demethanizing stripper overhead water cooler.Liquid outlet is communicated with by the opening for feed of the outer downstream processing system of demethanizing air lift column bottoms pump and native system at the bottom of the tower of demethanizing gas stripping column.
The air outlet, top of demethanizing rectifying tower is communicated with the opening for feed of demethanizing tower return tank by demethanizing rectifying tower condenser.The pipeline of the bottom liquid outlet of demethanizing rectifying tower is divided into two: one is communicated with the fluid inlet of demethanizing gas stripping column the superiors tower trays by demethanizing gas stripping column reflux pump, in order to provide phegma to the demethanizing gas stripping column; Another each plate-fin heat exchanger by demethanizing rectifying tower condenser and front cold series is communicated with the feeding gas compressor first paragraph entrance of upstream, consists of carbon one, carbon two refrigeration cycles.The bottom liquid outlet pipeline of demethanizing tower return tank is divided into two after by the demethanizing tower reflux pump: one is communicated with the fluid inlet of demethanizing rectifying tower the superiors tower trays, in order to provide phegma to the demethanizing rectifying tower; Another is communicated with the superiors' tower tray fluid inlet on carbon two absorption towers, in order to provide absorption agent to carbon two absorption towers.The outlet of demethanizing tower reflux pump provides the pipeline of absorption agent to carbon two absorption towers, or directly be communicated with the superiors' tower tray fluid inlet on carbon two absorption towers, or be communicated with the superiors' tower tray fluid inlet on carbon two absorption towers by demethanizing rectifying tower condenser, or is communicated with the superiors' tower tray fluid inlet on carbon two absorption towers by the outer methane, hydrogen interchanger of native system, or first by demethanizing rectifying tower condenser, pass through native system methane, hydrogen interchanger outward again and be communicated with the superiors' tower tray fluid inlet on carbon two absorption towers.The air outlet, top of demethanizing tower return tank is communicated with the opening for feed of native system resurgent gases/fuel gas system outward by each plate-fin heat exchanger of expansion-recompression machine, demethanizing rectifying tower condenser and front cold series.
For the liquid-absorbant on described carbon two absorption towers, can select different and suitable condensate depression realizes the control to ethylene content in the tail gas according to the intention of optimization design, reclaim the ethene of possible loss in tail gas more economically.For example: can select liquid-absorbant without excessively cold, and directly enter carbon two absorption towers with saturated mode; Perhaps select the liquid-absorbant demethanizing rectifying tower condenser of flowing through, by shallow spend cold (condensate depression is 8-16 ℃) laggard to carbon two absorption towers; Perhaps select the liquid-absorbant outer methane, hydrogen interchanger of native system of flowing through (to be positioned at methane hydrogen separating unit.Together lower), laggard to carbon two absorption towers by the degree of depth excessively cold (condensate depression is 22-30 ℃); Perhaps select the liquid-absorbant outer methane, hydrogen interchanger of demethanizing rectifying tower condenser and native system of flowing through successively, by twice cold (condensate depression is 22-30 ℃) laggard carbon two absorption towers of arriving with excessivelying.
The lighter hydrocarbons that wherein said carbon one, the carbon two refrigeration cycle logistics of taking from the bottom of the demethanizing rectifying tower are one take carbon one, C-2-fraction as main ingredient.Its flow through successively cold user of each different potential temperatures, the first paragraph of getting back to the feeding gas compressor of upstream is recompressed, and then circulation, is-130～-125 ℃ cold for system provides minimum potential temperature.
System of the present utility model, wherein preferred described demethanizing gas stripping column adopts 13.0 ~ 14.0Bar (a) tower to press, and described demethanizing rectifying tower adopts 12.8 ~ 13.8Bar (a) tower to press, and described carbon two absorption towers adopt 31.0 ~ 32.0Bar (a) tower to press.
The utility model provides a kind of system that uses the lean solution effect to reclaim ethene in the tail gas in the demethanizing process, only increases small investment, just can in control tail gas in the ethylene loss, receive preferably energy-saving effect.
Each " level " separating device of cold series before the utility model cooperates with the absorption tower first is with almost all hydrogen and a part of methane separation out allow remaining another part methane and whole C almost again in the charging
2 +Advance the separation column fractionation.In this process, absorption agent optimum solvation C
2 +Characteristic, make the ethene of possible loss in tail gas be recovered more thoroughly.The absorption agent on absorption tower is from internal system " lean solution ", the i.e. part of certain separation column phegma.
Compare with the prior art that front cold " level " is become the fractionation subsystem with polylith theoretical stage, the effect of ethylene loss is more excellent in the utility model control tail gas, and energy consumption is lower, invests also lower.
The utility model is applicable to lighter hydrocarbons and separates all types of C
1 -/ C
2 +Sepn process.
Below in conjunction with accompanying drawing the utility model is described further with the lean solution effect reclaims ethene in the tail gas in the demethanizing process system.
Description of drawings
Degree of depth of Fig. 1 absorption agent of the present utility model is crossed cold scheme schematic flow sheet;
Fig. 2 absorption agent of the present utility model is once shallow spends cold scheme schematic flow sheet;
Fig. 3 absorption agent of the present utility model is crossed cold scheme schematic flow sheet twice;
Fig. 4 absorption agent of the present utility model is cold scheme schematic flow sheet only;
The existing tail gas rectifying tower technology of Fig. 5 is applied to demethanizing process flow synoptic diagram.
Description of reference numerals: 01-demethanizing gas stripping column; 02-demethanizing rectifying tower; 03-carbon two absorption towers; 04-the first demethanizing tower charging separating tank; 05-the second demethanizing tower charging separating tank; 06-the 3rd demethanizing tower charging separating tank; 07-demethanizing tower return tank; 08-demethanizing gas stripping column reboiler; Demethanizing tower feed exchanger of 09-; No. two demethanizing tower feed exchangers of 10-; No. three demethanizing tower feed exchangers of 11-; No. four demethanizing tower feed exchangers of 12-; 13-demethanizing stripper overhead water cooler; 14-demethanizing rectifying tower condenser; 15-methane, hydrogen interchanger (being positioned at the outer methane hydrogen separating unit of native system); 16-demethanizing air lift column bottoms pump; 17-demethanizing gas stripping column reflux pump; 18-demethanizing tower reflux pump; 19-expands-the recompression machine; 20-tail gas rectifying tower; 21-tail gas rectifying tower return tank; The C3R-propylene refrigerant; The LPS-low-pressure steam; C2R-ethene cryogen; RC1/C2-carbon one, carbon two refrigeration cycle logistics; PR-serves as the process stream of cryogen or thermit powder.
Embodiment
Below be embodiment and processing parameter thereof etc., but content of the present utility model is not limited to the scope of these embodiment.
As shown in Figure 1, degree of depth of absorption agent of the present utility model is crossed cold scheme, comprises demethanizing gas stripping column 01, demethanizing rectifying tower 02, in-built tower tray or the filler that is equivalent to about 6 ~ 7 blocks of reason plates of carbon two absorption tower 03(), the first demethanizing tower charging separating tank 04, the second demethanizing tower charging separating tank 05, the 3rd demethanizing tower charging separating tank 06, demethanizing tower return tank 07, demethanizing gas stripping column reboiler 08, a demethanizing tower feed exchanger 09, No. two demethanizing tower feed exchangers 10, No. three demethanizing tower feed exchangers 11, No. four demethanizing tower feed exchangers 12, demethanizing stripper overhead water cooler 13, demethanizing rectifying tower condenser 14, methane, hydrogen interchanger (native system is outer) 15, demethanizing air lift column bottoms pump 16, demethanizing gas stripping column reflux pump 17, demethanizing tower reflux pump 18, expansion-recompression machine 19.Wherein:
The combined feed total feed pipeline is communicated with the opening for feed of the first demethanizing tower charging separating tank 04 by a demethanizing tower feed exchanger 09, introduces feeding gas.Described combined feed total feed pipeline also is communicated with the opening for feed of the first demethanizing tower charging separating tank 04 by demethanizing gas stripping column reboiler 08 and other relevant interchanger, introduces feeding gas.
The air outlet, top of the first demethanizing tower charging separating tank 04 is communicated with the opening for feed of the second demethanizing tower charging separating tank 05 by No. two demethanizing tower feed exchangers 10, the air outlet, top of the second demethanizing tower charging separating tank 05 is communicated with the opening for feed of the 3rd demethanizing tower charging separating tank 06 by No. three demethanizing tower feed exchangers 11, and the air outlet, top of the 3rd demethanizing tower charging separating tank 06 is communicated with the downside opening for feed on carbon two absorption towers 03 by No. four demethanizing tower feed exchangers 12.The bottom discharge port of the first demethanizing tower charging separating tank 04, the second demethanizing tower charging separating tank 05, the 3rd demethanizing tower charging separating tank 06 is communicated with three opening for feeds of demethanizing gas stripping column 01 respectively.
The air outlet, top on carbon two absorption towers 03 is communicated with native system methane hydrogen separating unit inlet mouth outward, and the bottom liquid outlet on carbon two absorption towers 03 is communicated with the upside opening for feed of demethanizing rectifying tower 02.
The air outlet, top of demethanizing gas stripping column 01 is communicated with the downside opening for feed of demethanizing rectifying tower 02 by demethanizing stripper overhead water cooler 13, and liquid outlet is communicated with the opening for feed of downstream processing system by some tube and shell heat exchanger of demethanizing air lift column bottoms pump 16 and precooling feeding gas at the bottom of the tower of demethanizing gas stripping column 01.
The air outlet, top of demethanizing rectifying tower 02 is communicated with the opening for feed of demethanizing tower return tank 07 by demethanizing rectifying tower condenser 14.The pipeline of the bottom liquid outlet of demethanizing rectifying tower 02 is divided into two: one is communicated with by the fluid inlet of demethanizing gas stripping column reflux pump 17 with demethanizing gas stripping column 01 the superiors' tower tray, in order to provide phegma to the demethanizing gas stripping column; Another is communicated with feeding gas compressor first paragraph entrance (not marking among the figure) by the plate-fin heat exchanger of cold series before demethanizing rectifying tower condenser 14 and No. four demethanizing tower feed exchangers 12, No. three demethanizing tower feed exchangers 11, No. two demethanizing tower feed exchangers 10, the demethanizing tower feed exchanger 09 etc. successively, formation carbon one, carbon two refrigeration cycles.
The bottom liquid outlet pipeline of demethanizing tower return tank 07 is divided into two after by demethanizing tower reflux pump 18: the fluid inlet with demethanizing rectifying tower 02 the superiors' tower tray is communicated with, in order to provide phegma to demethanizing rectifying tower 02; Another is by outer methane, hydrogen interchanger 15 (the methane hydrogen separating unit that contains this methane, hydrogen interchanger of native system, shown in long and short dash line among Fig. 1) be communicated with the superiors' tower tray fluid inlet on carbon two absorption towers 03, in order to provide absorption agent to carbon two absorption towers 03.The air outlet, top of demethanizing tower return tank 07 by the plate-fin heat exchanger of cold series before expansion-recompression machine 19, demethanizing rectifying tower condenser 14 and No. four demethanizing tower feed exchangers 12, No. three demethanizing tower feed exchangers 11, No. two demethanizing tower feed exchangers 10, the demethanizing tower feed exchanger 09 etc., is communicated with the opening for feed of native system resurgent gases/fuel gas system outward successively.
Described demethanizing gas stripping column 01 adopts 13.0 ~ 14.0Bar (a) tower to press, and described demethanizing rectifying tower 02 adopts 12.8 ~ 13.8Bar (a) tower to press, and described carbon two absorption towers 03 adopt 31.0 ~ 32.0Bar (a) tower to press.
The concrete technology method is as follows:
Feeding gas (hydrogen, methane, C in the multistage pressurization of upstream process, cooling condensation, gas-liquid separation and depickling gas, dehydration
2 +) enter front end Quench series (being called for short " front cold ") again by step by step cooling, condensation, flash distillation.Therebetween, feeding gas is successively through No. one, No. two, No. three demethanizing tower feed exchangers 09,10,11, and first, second, third demethanizing tower charging separating tank 04,05,06, isolates gaseous phase materials and multiply liquid phase material.Described gaseous phase materials is for containing a small amount of C
2 +The hydrogen of cut and methane miscellany are through entering carbon two absorption towers 03 (in-built tower tray or the fillers that are equivalent to about 6 ~ 7 blocks of reason plates) after the cooling of No. four demethanizing tower feed exchangers 12 and the partial condensation.Described multiply liquid phase material enters respectively the different feeds plate (adopting the multiply charging is the practices well of fractionation process) of demethanizing gas stripping column 01.
In carbon two absorption towers 03, feeding gas with from demethanizing tower reflux pump 18, the methane, hydrogen interchanger outside native system 15 by reverse contact of the excessively cold liquid-absorbant of the degree of depth (i.e. " lean solution ").In the feeding gas lower, the ethylene content of solubleness also lower hydrogen and methane mixture overflow (this is tail gas) from cat head because being dissolved in absorption agent, be sent to the outer hydrogen/methane separation element of native system.Also higher C of higher, the ethylene content of solubleness in the feeding gas
1 +Cut is dissolved in the supercooled state liquid-absorbant.Be dissolved with described C
1 +The liquid-absorbant of cut (i.e. " rich solution ") is entered demethanizing rectifying tower 02 by extraction at the bottom of 03 tower of carbon two absorption towers.
In demethanizing gas stripping column 01, the lighter fraction in the charging---with a small amount of C
2 +The methane of cut, is distillated from cat head to cat head by air lift.Overhead product in demethanizing stripper overhead water cooler 13, be cooled and partial condensation after enter demethanizing rectifying tower 02.Demethanizing gas stripping column 01 the bottomsstream is not for the C of methane
2 +Cut is extracted out by demethanizing air lift column bottoms pump 16, after relevant interchanger heat exchange, delivers to down-stream system and processes.
From at the bottom of 03 tower of carbon two absorption towers and two bursts of chargings of demethanizing stripper overhead water cooler 13, enter respectively demethanizing rectifying tower 02, under the acting in conjunction from the phegma of demethanizing tower return tank 07 and upstream, a small amount of C in the methane
2 +Cut is brought at the bottom of the tower.Removed C
2 +The methane of cut distillates from cat head, in demethanizing rectifying tower condenser 14, be cooled and partial condensation after, in demethanizing tower return tank 07, be divided into gas-liquid two-phase.Liquid phase wherein is divided into again two strands after being extracted out by demethanizing tower reflux pump 18: one gets back to demethanizing rectifying tower 02 as phegma; The methane, hydrogen interchanger 15(of another plume outside native system contains the methane hydrogen separating unit of this methane, hydrogen interchanger, shown in long and short dash line among Fig. 1) by the degree of depth excessively cold (condensate depression 22-30 ℃) laggard to carbon two absorption towers 03 as described liquid-absorbant.The gas phase of demethanizing tower return tank 07, the plate- fin heat exchanger 12,11,10 of expansion-recompression machine 19, demethanizing rectifying tower condenser 14 and the front cold series of flowing through, 09 etc., cold is provided and after self being heated, goes to the outer resurgent gases/fuel gas system of native system.
In demethanizing rectifying tower 02, the C that from methane, tells
2 +Cut is down at the bottom of the tower, is plucked out of with materials at bottom of tower.The material of extraction is divided into two strands: one is sent back to demethanizing gas stripping column 01 as the phegma of demethanizing gas stripping column 01 by demethanizing gas tower reflux pump 17; Another is strand as carbon one, carbon two refrigeration cycle logistics, and the plate- fin heat exchanger 12,11,10 of flow through demethanizing rectifying tower condenser 14 and front cold series, 09 etc. is got back to the first paragraph of the feeding gas compressor of upstream, is recompressed, recirculation.
The lighter hydrocarbons that carbon one, the carbon two refrigeration cycle logistics of extraction are one take carbon one, C-2-fraction as main ingredient at the bottom of demethanizing rectifying tower 02 tower.Its flow through successively cold user of each different potential temperatures, the first paragraph of getting back to the feeding gas compressor is recompressed, recirculation, is-130～-125 ℃ cold for the demethanizing system provides minimum potential temperature.
Described demethanizing gas stripping column 01 adopts 13.0 ~ 14.0Bar (a) tower to press, and described demethanizing rectifying tower 02 adopts 12.8 ~ 13.8Bar (a) tower to press, and described carbon two absorption towers 03 adopt 31.0 ~ 32.0Bar (a) tower to press.
Wherein for the liquid-absorbant on described carbon two absorption towers 03, can select different and suitable condensate depression realizes the control to ethylene content in the tail gas according to the intention of optimization design, reclaim the ethene of possible loss in tail gas more economically.In other embodiment, the liquid-absorbant on carbon two absorption towers 03 can directly enter carbon two absorption tower 03(as shown in Figure 4 without cold), the demethanizing rectifying tower condenser 14 of perhaps flowing through is spent the cold laggard carbon two absorption tower 03(of arriving as shown in Figure 2 by shallow), the outer methane, hydrogen interchanger 15 of perhaps flow through successively demethanizing rectifying tower condenser 14 and native system is crossed the cold laggard carbon two absorption tower 03(of arriving as shown in Figure 3 by twice).In other words: except degree of depth of absorption agent shown in Figure 1 excessively cold (condensate depression 22-30 ℃) scheme, the liquid-absorbant on described carbon two absorption towers 03 can also be saturated mode, need not be excessively cold; Also can be with once realizing cold (condensate depression 8-16 ℃) with the heat exchange of lesser temps material; Also can be first and the lesser temps material, again with the lower temperature material-heat-exchanging, realized at twice cold (condensate depression 22-30 ℃).
Degree of depth of embodiment absorption agent of the present utility model is crossed cold scheme
When degree of depth of absorption agent of the present utility model was crossed cold scheme and is applied to produce per year 700,000 tons of ethylene units, mainly relevant processing parameter was as shown in table 1 for it.Fig. 1 is its schematic flow sheet.
The main relevant processing parameter of table 1 embodiment
| |
100 | 110 | 120 | 130 | 140 | 150 | 160 |
| Stream burst title | Combined feed total feed | The final stage charging | Tail gas | DC1 top methane | C2+ | RC1/C2 | Absorption agent |
| Temperature, ℃ | 15.30 | -116.80 | -122.23 | -118.76 | -30.17 | -127.75 | -146.00 |
| Pressure, Bar (a) | 33.80 | 32.35 | 32.20 | 12.80 | 13.55 | 1.90 | 32.20 |
| Molecular weight | 23.98 | 9.75 | 7.97 | 15.19 | 32.47 | 23.71 | 17.00 |
| Mass rate, kg/h | 206017.24 | 22317.50 | 15475.81 | 19423.77 | 162188.90 | 8931.74 | 2531.68 |
| Component, massfraction | |||||||
| H2 | 0.01196 | 0.10343 | 0.14757 | 0.00927 | 0.00000 | 0.00007 | 0.00021 |
| Methane | 0.16379 | 0.72500 | 0.81822 | 0.97141 | 0.00006 | 0.24677 | 0.86507 |
| CO | 0.00269 | 0.01934 | 0.02567 | 0.00789 | 0.00000 | 0.00038 | 0.00138 |
| CO2 | 0.00000 | 0.00000 | 0.00000 | 0.00000 | 0.00000 | 0.00000 | 0.00000 |
| H2S | 0.00000 | 0.00000 | 0.00000 | 0.00000 | 0.00000 | 0.00000 | 0.00000 |
| Acetylene | 0.00711 | 0.00101 | 0.00001 | 0.00002 | 0.00873 | 0.00533 | 0.00047 |
| Ethene | 0.45662 | 0.14265 | 0.00846 | 0.01131 | 0.53892 | 0.70721 | 0.12965 |
| Ethane | 0.09388 | 0.00836 | 0.00007 | 0.00010 | 0.11706 | 0.03938 | 0.00321 |
| Methylacetylene | 0.00391 | 0.00000 | 0.00000 | 0.00000 | 0.00497 | 0.00000 | 0.00000 |
| Propadiene | 0.00277 | 0.00000 | 0.00000 | 0.00000 | 0.00351 | 0.00000 | 0.00000 |
| Propylene | 0.17205 | 0.00020 | 0.00000 | 0.00000 | 0.21850 | 0.00084 | 0.00001 |
| Propane | 0.00431 | 0.00000 | 0.00000 | 0.00000 | 0.00547 | 0.00001 | 0.00000 |
| Vinylacetylene | 0.00030 | 0.00000 | 0.00000 | 0.00000 | 0.00038 | 0.00000 | 0.00000 |
| 1,3-butadiene | 0.03934 | 0.00000 | 0.00000 | 0.00000 | 0.04997 | 0.00000 | 0.00000 |
| 1-butylene | 0.03129 | 0.00000 | 0.00000 | 0.00000 | 0.03975 | 0.00000 | 0.00000 |
| Butane | 0.00032 | 0.00000 | 0.00000 | 0.00000 | 0.00041 | 0.00000 | 0.00000 |
| Cyclopentadiene | 0.00307 | 0.00000 | 0.00000 | 0.00000 | 0.00390 | 0.00000 | 0.00000 |
| Isoprene | 0.00579 | 0.00000 | 0.00000 | 0.00000 | 0.00735 | 0.00000 | 0.00000 |
| Benzene | 0.00066 | 0.00000 | 0.00000 | 0.00000 | 0.00084 | 0.00000 | 0.00000 |
| Cyclohexadiene | 0.00013 | 0.00000 | 0.00000 | 0.00000 | 0.00016 | 0.00000 | 0.00000 |
| Toluene | 0.00001 | 0.00000 | 0.00000 | 0.00000 | 0.00001 | 0.00000 | 0.00000 |
Annotate: DC1 represents the demethanizing rectifying tower
In the utility model implementation process, in order to study the contrast effect of the utility model and prior art, imagination for the demethanizing process of producing 700000 tons of ethylene units per year, has proposed following technical scheme with existing tail gas rectifying tower technology, is called " Comparative Examples ".Fig. 5 is the schematic flow sheet of Comparative Examples.
As shown in Figure 5:
Feeding gas (hydrogen, methane, C in the multistage pressurization of upstream process, cooling condensation, gas-liquid separation and depickling gas, dehydration
2 +) enter front end Quench series (being called for short " front cold ") again by step by step cooling, condensation, flash distillation.Therebetween, feeding gas is successively through No. one, No. two, No. three demethanizing tower feed exchangers 09,10,11, and first, second, third demethanizing tower charging separating tank 04,05,06, isolates gaseous phase materials and multiply liquid phase material.Described gaseous phase materials is for containing a small amount of C
2 +The hydrogen of cut and methane miscellany are through entering tail gas rectifying tower 20 after the cooling of No. four demethanizing tower feed exchangers 12 and the partial condensation.Tail gas rectifying tower 20 is conventional rectifying tower, the tail gas rectifying tower return tank 21 high-order layouts that just cooperate with it, and phegma can fall by gravity and flow to the superiors' tower tray or filler, need not reflux pump pressure head is provided.Described multiply liquid phase material enters respectively the different feeds plate (adopting the multiply charging is the practices well of fractionation process) of demethanizing gas stripping column 01.
In tail gas rectifying tower 20, under the acting in conjunction from the phegma of tail gas rectifying tower return tank 21 and upstream, methane and hydrogen mixture that volatility is higher, ethylene content is lower distillate from cat head, the demethanizing rectifying tower condenser 14 of flowing through is cooled and partial condensation in the different runners of same demethanizing rectifying tower condenser 14 from the overhead product of demethanizing rectifying tower 02.The partial condensation thing is divided into gas-liquid two-phase in tail gas rectifying tower return tank 21: gaseous phase materials is tail gas, is sent to the outer methane hydrogen separating unit (shown in long and short dash line among Fig. 5) of native system; Liquid phase material returns the superiors' tower tray of tail gas rectifying tower 20 as phegma.In tail gas rectifying tower 20, the C that volatility is lower, ethylene content is higher
1 +Cut is down at the bottom of the tower, and then extraction at the bottom of tail gas rectifying tower 20 towers enters demethanizing rectifying tower 02, becomes one of charging of demethanizing rectifying tower 02.
In demethanizing gas stripping column 01, the lighter fraction in the charging---with a small amount of C
2 +The methane of cut, is distillated from cat head to cat head by air lift.Overhead product in demethanizing stripper overhead water cooler 13, be cooled and partial condensation after enter demethanizing rectifying tower 02.Demethanizing gas stripping column 01 the bottomsstream is not for the C of methane
2 +Cut is extracted out by demethanizing air lift column bottoms pump 16, after relevant interchanger heat exchange, delivers to down-stream system and processes.
From at the bottom of tail gas rectifying tower 20 towers and two bursts of chargings of demethanizing stripper overhead water cooler 13, enter respectively demethanizing rectifying tower 02, under the acting in conjunction from the phegma of demethanizing tower return tank 07 and upstream, a small amount of C in the methane
2 +Cut is brought at the bottom of the tower.Removed C
2 +The methane of cut distillates from cat head, in demethanizing rectifying tower condenser 14, be cooled and partial condensation after, in demethanizing tower return tank 07, be divided into gas-liquid two-phase.Liquid phase is wherein got back to demethanizing rectifying tower 02 as phegma after being extracted out by demethanizing tower reflux pump 17.The gas phase of demethanizing tower return tank 07, the plate- fin heat exchanger 12,11,10 of expansion-recompression machine 19, demethanizing rectifying tower condenser 14 and the front cold series of flowing through, 09 etc., cold is provided and after self being heated, goes to the outer resurgent gases/fuel gas system of native system.
In demethanizing rectifying tower 02, the C that from methane, tells
2 +Cut is down at the bottom of the tower, is plucked out of with materials at bottom of tower.The material of extraction is divided into two strands: one is sent back to demethanizing gas stripping column 01 as the phegma of demethanizing gas stripping column 01 by demethanizing gas stripping column reflux pump 17; Another is strand as carbon one, carbon two refrigeration cycle logistics, and the plate- fin heat exchanger 12,11,10 of flow through demethanizing rectifying tower condenser 14 and front cold series, 09 etc. is got back to the first paragraph of the feeding gas compressor of upstream, is recompressed, recirculation.
Demethanizing gas stripping column 01 adopts about 13.6Bar (a) tower to press, and demethanizing rectifying tower 02 adopts about 13.3Bar (a) tower to press, and tail gas rectifying tower 20 adopts about 31.6Bar (a) tower to press.
The main relevant processing parameter of Comparative Examples is as shown in table 2.
The main relevant processing parameter of table 2 Comparative Examples
| |
100 | 110 | 120 | 130 | 140 | 150 |
| Stream burst title | Combined feed total feed | The final stage charging | Tail gas | DC1 top methane | C2+ | RC1/C2 |
| Temperature, ℃ | 15.30 | -116.80 | -122.50 | -118.69 | -29.92 | -129.31 |
| Pressure, Bar (a) | 33.80 | 32.35 | 32.15 | 12.80 | 13.55 | 1.90 |
| Molecular weight | 23.98 | 9.76 | 7.66 | 15.22 | 32.55 | 23.51 |
| Mass rate, kgh | 206017.24 | 22355.17 | 14313.80 | 19632.91 | 159710.66 | 12359.31 |
| Component, massfraction | ||||||
| H2 | 0.01196 | 0.10326 | 0.15980 | 0.00898 | 0.00000 | 0.00007 |
| Methane | 0.16379 | 0.72453 | 0.79891 | 0.97202 | 0.00006 | 0.26013 |
| CO | 0.00269 | 0.01931 | 0.02795 | 0.00760 | 0.00000 | 0.00040 |
| CO2 | 0.00000 | 0.00000 | 0.00000 | 0.00000 | 0.00000 | 0.00000 |
| H2S | 0.00000 | 0.00000 | 0.00000 | 0.00000 | 0.00000 | 0.00000 |
| Acetylene | 0.00711 | 0.00102 | 0.00000 | 0.00002 | 0.00875 | 0.00544 |
| Ethene | 0.45662 | 0.14326 | 0.01333 | 0.01129 | 0.53287 | 0.69213 |
| Ethane | 0.09388 | 0.00841 | 0.00001 | 0.00011 | 0.11792 | 0.04088 |
| Methylacetylene | 0.00391 | 0.00000 | 0.00000 | 0.00000 | 0.00504 | 0.00000 |
| Propadiene | 0.00277 | 0.00000 | 0.00000 | 0.00000 | 0.00357 | 0.00000 |
| Propylene | 0.17205 | 0.00020 | 0.00000 | 0.00000 | 0.22186 | 0.00093 |
| Propane | 0.00431 | 0.00000 | 0.00000 | 0.00000 | 0.00555 | 0.00001 |
| Vinylacetylene | 0.00030 | 0.00000 | 0.00000 | 0.00000 | 0.00039 | 0.00000 |
| 1,3-butadiene | 0.03934 | 0.00000 | 0.00000 | 0.00000 | 0.05074 | 0.00000 |
| 1-butylene | 0.03129 | 0.00000 | 0.00000 | 0.00000 | 0.04037 | 0.00000 |
| Butane | 0.00032 | 0.00000 | 0.00000 | 0.00000 | 0.00042 | 0.00000 |
| Cyclopentadiene | 0.00307 | 0.00000 | 0.00000 | 0.00000 | 0.00396 | 0.00000 |
| Isoprene | 0.00579 | 0.00000 | 0.00000 | 0.00000 | 0.00747 | 0.00000 |
| Benzene | 0.00066 | 0.00000 | 0.00000 | 0.00000 | 0.00086 | 0.00000 |
| Cyclohexadiene | 0.00013 | 0.00000 | 0.00000 | 0.00000 | 0.00016 | 0.00000 |
| Toluene | 0.00001 | 0.00000 | 0.00000 | 0.00000 | 0.00001 | 0.00000 |
Annotate: DC1 represents the demethanizing rectifying tower
The utility model can be according to the intention of optimization design, selects different and suitable liquid-absorbant condensate depression realizes the control to ethylene content in the tail gas, reclaims the ethene of possible loss in tail gas more economically.Embodiment adopts the degree of depth to cross and is as cold as approximately-146.0 ℃ liquid-absorbant, the ethylene content in the tail gas can be controlled at about 0.85m%.The formation contrast is therewith, and the phegma of any separation column all can only be condensation or the partial condensation thing that this column overhead distillates gas, is subject to balancing each other of system, and the adjustable temperature range relative narrower of described phegma is difficult to carry out same optimal control.In Comparative Examples, their tail gas ethylene content all has to maintain about 1.33m%, and is larger more than 50% than embodiment.
However, the energy consumption of Comparative Examples still is higher than embodiment.Take a device that overlaps 700,000 tons of ethene of annual output as benchmark, in the identical situation of other condition, embodiment lacks the about 750kwh/h of power consumption than Comparative Examples saving energy 5.2%.See Table 3.
The energy consumption data of table 3 embodiment and Comparative Examples relatively
Annotate: in the mechanical work that Comparative Examples consumes, some is after the RC1/C2 internal circulating load increases, recycle stock to be compressed institute's energy requirement again.
Above-described embodiment is described preferred implementation of the present utility model; be not that scope of the present utility model is limited; under the prerequisite that does not break away from the utility model design spirit; various distortion and improvement that those of ordinary skills make the technical solution of the utility model all should fall in the definite protection domain of the utility model claims.
Claims (3)
1. one kind is reclaimed the system of ethene in the tail gas with the lean solution effect in the demethanizing process, comprises front end Quench series, demethanizing gas stripping column, demethanizing rectifying tower, carbon two absorption towers, demethanizing tower return tank, demethanizing rectifying tower condenser, expansion-recompression machine; Wherein front end Quench series contains many demethanizing tower feed exchangers and Duo Tai demethanizing tower charging separating tank;
The combined feed total feed pipeline is communicated with the opening for feed of the first demethanizing tower charging separating tank by a demethanizing tower feed exchanger, introduces feeding gas; Described combined feed total feed pipeline also is communicated with by the opening for feed of interchanger with the first demethanizing tower charging separating tank, introduces feeding gas;
The air outlet, top of the first demethanizing tower charging separating tank is communicated with the second demethanizing tower charging separating tank opening for feed by No. two demethanizing tower feed exchangers, the air outlet, top of the second demethanizing tower charging separating tank is communicated with the 3rd demethanizing tower charging separating tank opening for feed by No. three demethanizing tower feed exchangers, and the air outlet, top of the 3rd demethanizing tower charging separating tank is communicated with the downside opening for feed on carbon two absorption towers by No. four demethanizing tower feed exchangers;
The bottom discharge port of first, second, third demethanizing tower charging separating tank is communicated with three opening for feeds of demethanizing gas stripping column respectively;
The air outlet, top on carbon two absorption towers is communicated with native system methane, hydrogen interchanger inlet mouth outward, and its bottom liquid outlet is communicated with the upside opening for feed of demethanizing rectifying tower;
The air outlet, top of demethanizing gas stripping column is communicated with the downside opening for feed of demethanizing rectifying tower by demethanizing stripper overhead water cooler, and liquid outlet is communicated with by the opening for feed of the outer downstream processing system of demethanizing air lift column bottoms pump and native system at the bottom of the tower of demethanizing gas stripping column;
The air outlet, top of demethanizing rectifying tower is communicated with the opening for feed of demethanizing tower return tank by demethanizing rectifying tower condenser; The pipeline of the bottom liquid outlet of demethanizing rectifying tower is divided into two, one is communicated with the fluid inlet of demethanizing gas stripping column the superiors tower trays, in order to provide phegma to the demethanizing gas stripping column, another is communicated with the feeding gas compressor first paragraph entrance of upstream by demethanizing rectifying tower condenser, demethanizing tower feed exchanger and other plate-fin heat exchanger of front end Quench, consists of carbon one, carbon two refrigeration cycles;
The bottom liquid outlet pipeline of demethanizing tower return tank is divided into two after by the demethanizing tower reflux pump: one is communicated with in order to provide phegma to the demethanizing rectifying tower with the fluid inlet of demethanizing rectifying tower the superiors tower trays, another is communicated with the superiors' tower tray fluid inlet on carbon two absorption towers, in order to provide absorption agent to carbon two absorption towers;
The air outlet, top of demethanizing tower return tank is communicated with the opening for feed of native system resurgent gases/fuel gas system outward by other plate-fin heat exchanger of expansion-recompression machine, demethanizing rectifying tower condenser and front end Quench series.
2. system according to claim 1, it is characterized in that: describedly provide the pipeline of absorption agent to carbon two absorption towers by that tell behind the demethanizing tower reflux pump, perhaps directly be communicated with the superiors' tower tray fluid inlet on carbon two absorption towers, perhaps be communicated with the superiors' tower tray fluid inlet on carbon two absorption towers by demethanizing rectifying tower condenser, perhaps be communicated with the superiors' tower tray fluid inlet on carbon two absorption towers by the outer methane, hydrogen interchanger of native system, perhaps be communicated with the superiors' tower tray fluid inlet on carbon two absorption towers by demethanizing rectifying tower condenser and the outer methane, hydrogen interchanger of native system successively.
3. system according to claim 1, it is characterized in that: described demethanizing gas stripping column adopts 13.0 ~ 14.0Bar (a) tower to press, described demethanizing rectifying tower adopts 12.8 ~ 13.8Bar (a) tower to press, and described carbon two absorption towers adopt 31.0 ~ 32.0Bar (a) tower to press.
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| CN103449950A (en) * | 2012-11-19 | 2013-12-18 | 中国寰球工程公司 | Method and system for recycling ethylene in tail gas through barren liquor effect in demethanization process |
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| CN103449950A (en) * | 2012-11-19 | 2013-12-18 | 中国寰球工程公司 | Method and system for recycling ethylene in tail gas through barren liquor effect in demethanization process |
| CN103449950B (en) * | 2012-11-19 | 2015-04-01 | 中国寰球工程公司 | Method and system for recycling ethylene in tail gas through barren liquor effect in demethanization process |
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Address after: Two road 100012 Beijing city Chaoyang District high tech Industrial Park, No. 1. Patentee after: CHINA HUANQIU CONTRACTING & ENGINEERING Co.,Ltd. Address before: 100029 Beijing city Chaoyang District cherry Garden Street No. 7 Patentee before: China Huanqiu Contracting & Engineering Corp. |
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