CN1107381A

CN1107381A - Improved adsorption separation process for simulation moving bed

Info

Publication number: CN1107381A
Application number: CN 94118796
Authority: CN
Inventors: 潘伟忠; 王玉冰; 周文; 李友松; 薛玉松; 陈维民
Original assignee: YANGZI PETRO-CHEMICAL Co CHINA PETRO-CHEMICAL CORP
Current assignee: YANGZI PETRO-CHEMICAL Co CHINA PETRO-CHEMICAL CORP
Priority date: 1994-12-07
Filing date: 1994-12-07
Publication date: 1995-08-30
Anticipated expiration: 2014-12-07
Also published as: CN1036050C

Abstract

The improved adsorptive separation process features its calculation formula about eluent flow, where the flow of eluent is related to volume of each pipe and volume factor is introduced. Under program control, different flows of eluent are used for different beds of pipes, so reducing consumption of eluent and increasing purity and yield of product.

Description

Improved adsorption separation process for simulation moving bed

The present invention relates to a kind of adsorption separating method.More particularly, the present invention relates to can comprise one or more compositions from easy absorbed component A() and be difficult for separating the method for a kind of component or several components by the selective absorption of adsorbent the incoming mixture that absorbed component B(can comprise a kind of component or several compositions.Classification number belongs to BO1D15/00.

Adsorption separating method can carry out in fixed adsorption bed or mobile adsorbent bed system, but preferably carries out in the adverse current simulated moving bed system.For example, US2985589, US3268604 and US3268605 disclose the adverse current simulated moving bed system that is used for adsorption separation process, and U.S. Pat 3040777 and US3422848 then disclose the rotary valve that is used for above-mentioned adverse current simulated moving bed system.Below, we will further specify existing defective in the prior art, purpose of the present invention and solution with reference to the accompanying drawings.

Accompanying drawing 1 is the principle schematic of continuous flow upstream simulated moving bed system.

Referring to Fig. 1, F representative contains easy absorbed component A and is difficult for the feed liquid of absorbed component B, and D represents strippant liquid, and E represents Extract, promptly contains the stripping liquid of easy absorbed component A, and R represents raffinate, promptly contains the raffinate after the absorption that is difficult for absorbed component B, H _AdvanceAnd H _{Go out}The once flushing liquid that is used for pipe flushing of strippant is rich in representative, and the X representative is used for the secondary flushing liquor of pipeline secondary flushing, and M represents that rotary valve switches simulation adsorbent moving direction.Adsorbent bed is divided into I, II, III and IV zone.The zone I between F and R, the feed liquid of adding in regional I with the adsorbent counter current contacting, easily absorbed component A transfers to from feed liquid in the adsorbent hole, simultaneously strippant D is cemented out from the hole.Therefore regional I is called adsorption zone.The zone II is between F and E, because adsorbent has also adsorbed a spot of absorbed component B that is difficult in the easy absorbed component A of absorption.In regional II, adsorbent contacts with the liquid that only contains A and D at the regional II top of coming, flow velocity by liquid in the suitable adjustment region II, be difficult for absorbed component B little by little by easily absorbed component A and strippant D cement out from the hole, to be difficult for absorbed component B strong because the absorption of adsorbent commute absorbed component A will be compared, and easily absorbed component A can all not cemented out simultaneously, and easily absorbed component A obtains purifying in regional II, therefore, regional II is referred to as purification section.The zone III between E and D, in regional III, pure D with pass through regional II in the adsorbent of having purified contact, from the adsorbent hole, displace A, therefore, regional III is called desorption zone.The zone IV in regional IV, by setting the D flow velocity, upwards flows D material in regional IV between D and R, thereby does not allow component B enter in the liquid of regional III and pollute Extract, and therefore, regional IV is referred to as buffering area.

In simulation moving-bed, adsorption tower can contain the adsorbent bed of any amount, is generally 8-24 adsorbent bed, preferred 24 adsorbent beds.In operating process, adopt material switching device such as rotary valve etc. to switch, will pass in and out the material circulation and move, thus the simulation that realization is moved adsorbent.In the rotary valve handoff procedure, need to wash, with the purity and the rate of recovery of the component that guarantees to be purified to the residual solution in the bed pipeline.In accompanying drawing 1, marked H _Advance, H _{Go out}With the import and export position of X, in regional II and III, mark off respectively thus II ', II " and III ' three zone.

Setting H _Advance, H _{Go out}During flow, if flow is too little, then the flushing of the residue in the pipeline is unclean, the final purity and the rate of recovery that influences product, if flow is too big,, thereby cause the adsorbents adsorb space to be occupied by strippant then because flushing liquor is rich in strippant, reduce the adsorption capacity of adsorbent commute absorbed component, caused the rate of recovery of easy absorbed component and purity to descend.

In the prior art, flushing flow rate setting value H _AdvanceAnd H _{Go out}Calculate by following formula (I):

Wherein: V _L: 24 the longest one volumes of bed pipeline;

T: rotary valve interval switching time.

According to the volumetric balance to adsorption chamber, following formula calculates each regional flow:

Ⅰ=H+K+F

ⅡA=H+K

ⅡB=K-X

Ⅲ=K+E-X

ⅢA=K+E+H-X

Ⅳ=K+E+H-D-X

Wherein, H, X, F, E, D are respectively once flushing flow quantity, secondary flushing liquor flow, feed rate, Extract flow and strippant flow, and K then is the flow in selected II district.

Yet in practice, 24 bed pipelines of adsorbent bed can not be identical, and the longest bed pipeline differs bigger with the shortest bed pipeline volume.Therefore, calculate the flushing liquor flow with the longest bed pipeline volume in the above-mentioned formula and can cause the flushing liquor flow higher, thereby reduced the rate of recovery and the purity of product.

The computing formula that the purpose of this invention is to provide the once flushing flow quantity.

Computing formula by the once flushing flow that provides among the present invention calculates H _AdvanceAnd H _{Go out}No longer be a steady state value, but a variable utilizes programme-control, these two strands of materials periodically change according to the volume of each bed pipeline in the rotary valve handoff procedure.

The present invention relates to a kind of improved adsorption separating method, wherein utilize adsorption separation device from the feed liquid that contains component A and B, to isolate highly purified component A, described adsorbent equipment comprises adsorption zone, purification section, desorption zone and buffering area, this method comprises: the feed liquid that (1) adds in adsorption zone with the adsorbent counter current contacting, component A in the adsorbent selective absorption feed liquid, and the raffinate of B component that obtained enrichment; (2) in purification section, contact with the adsorbent that is adsorbed with component A that after step (1), obtains with the partially liq that contains component A and strippant, displacing the B component that is adsorbed in simultaneously in the step (1) in the adsorbent hole, thus the component A in the adsorbent hole of having purified; (3) in desorption zone, strippant contacts with the adsorbent that step (2) obtains, and separates the pure component A in the sucking-off adsorbent hole, has obtained Extract, and the part Extract is used for step (2), and remaining Extract then obtains highly purified component A through distillation; (4) in buffering area, control strippant flow velocity makes raffinate not enter desorption zone, has avoided the pollution of Extract; (5) spent material switching device such as rotary valve switch, and will pass in and out material and circulate mobilely, move thereby circulated in adsorbent equipment in above-mentioned four zones.In handoff procedure, use the flushing liquid be rich in strippant to rinse out residual solution in the bed pipeline, once flushing flow quantity H _Advance, H _{Go out}Calculate by following formula:

Wherein: K _n: H _AdvanceThe volume factor of the n bed pipeline at place,

Its value is at (0.5V _n)/(V _L) to (3.5V _n)/(V _L) between selected;

T: rotary valve interval switching time (h);

V _L: the longest bed pipeline volume (m ³).

With H _AdvanceAnd H _{Go out}Related one by one with each pipeline volume of adsorbent bed, utilize the once flushing flow quantity of each bed pipeline of programme-control, different bed pipelines washes with different flushing liquor flows, thereby makes it accurately be suitable for each bed pipeline, to improve the rate of recovery and the purity of component A.

Can be used for having had in the listed hereinbefore patent documentation of adsorbent, strippant, simulation moving-bed structure and the operating condition of adsorption separating method of the present invention and describe in detail, above-mentioned patent documentation draws the list of references for this paper.

Adopt the improved adsorption separating method of the present invention, under the prerequisite that guarantees developing result, the flushing liquor flow descends, thereby making the adsorption space that was originally occupied by strippant is that required product (as easy absorbed component A) occupies, thus, can improve yield 4-6%, product purity can increase 0.10-0.20%, and the device disposal ability also increases 3-5% indirectly.

Following examples are used to further specify method of the present invention and effect, rather than limitation of the invention.

Comparison example 1

The paraxylene adsorption separation device of raising aromatic hydrocarbons factory of sub-petro-chemical corporation with Sinopec is an example.Adsorption tower has 24 adsorption bed, and each root bed pipeline volume is as follows: (m ³)

0.74 0.59 0.55 0.54 0.57 0.56

0.67 0.69 0.68 0.68 0.71 0.77

*1.00 0.85 0.7 0.71 0.70 0.64

0.68 0.64 0.60 0.59 0.59 0.63

* the longest bed pipeline volume V _L

According to above-mentioned formula (I),

V _L=1.00m ³，T=101.4s=0.0281（h）

H then _Advance=H _{Go out}=(2 * 1.00)/0.281=71m ³/ h

It is as follows that adsorption chamber respectively passes in and out mass flow: (95% load)

F=224%m ³\h，D336m ³\h，E＝132m ³\h，X＝18m ³\h，R＝446m ³\h

H _Advance=H _{Go out}=71m ³H

Because 24 bed pipeline volumes differ greatly, maximum bed pipeline volume and amount lectulum layer pipeline volume differ about 85%, thereby make the once flushing flow bigger than normal, and running effect is not good.The yield of paraxylene is 90%, and product purity is 99.30%.

Embodiment 1

Adopt the device identical, except that H with comparison example 1 _AdvanceAnd H _{Go out}Outward, other adsorption chamber respectively passes in and out mass flow and remains unchanged.But the pipeline volume data according to 24 beds of device carries out H respectively _AdvanceAnd H _{Go out}Flow is adjusted, and finally calculates each H respectively with following volume factor _AdvanceAnd H _{Go out}(m ³):

1.50 1.20 1.10 1.10 1.20 1.10

1.40 1.40 1.40 1.40 1.40 1.50

2.00 1.70 1.50 1.40 1.40 1.50

1.40 1.30 1.20 1.20 1.20 1.30

Adopt formula (II), with once flushing flow setting value H _Advance, H _{Go out}Related one by one with 24 bed pipeline volumes, utilize the once flushing flow of each bed of programme-control.Behind the stable operation, once flushing material requirement has descended about 25%.The yield of paraxylene is 95%, and product purity is 99.46%.Paraxylene yield and product purity all obviously improve, and have obtained good benefit.

Claims

1, a kind of improved simulation moving-bed adsorption separating method, this method comprises:

(1) will contain easy absorbed component A and be difficult for absorbed component B feed liquid, and feed adsorption zone and make adsorbent counter current contacting in itself and this district, adsorbent optionally adsorbs the easy absorbed component A in the feed liquid, and has obtained enrichment and be difficult for the raffinate of absorbed component B;

(2) moving bed contains the liquid of easy absorbed component A and strippant and contacts in purification section with adsorbent after step (1), be difficult for absorbed component B to displace to be adsorbed in the step (1) in the adsorbent hole, thus the easy absorbed component A in the purification adsorbent hole;

(3) strippant contacts with adsorbent after step (2) in desorption zone, separates the easy absorbed component A in the sucking-off adsorbent hole, and obtains containing the Extract of easy absorbed component A, and Extract obtains highly purified product A through distillation;

(4) in buffering area, control strippant liquid flowing speed makes raffinate not enter desorption zone and pollutes Extract;

(5) the spent material switching device switches, so that it is mobile to circulate into and out of material, moves thereby circulated in adsorbent equipment in above-mentioned four zones, in handoff procedure, uses flushing liquor flushing bed, and the once flushing flow quantity is calculated as follows:

Wherein: K _n: H _AdvanceThe volume factor of the n bed at place,

Its value is selected between (0.5Vn)/(VL) to (3.5Vn)/(VL);

V _L: the longest bed pipeline volume (m ³);

T: switching time is (h) at interval

With H _AdvanceAnd H _{Go out}Be associated by volume factor with each bed pipeline volume of adsorbent bed, the flushing liquor flow of each bed pipeline of programme-control washes with different flushing liquor flows different bed pipelines.

2, by the process of claim 1 wherein that this method carries out in adverse current is simulation moving-bed.

3, by the process of claim 1 wherein that adsorption chamber is one or more.

4, by the process of claim 1 wherein that the material switching device is a rotary valve.

5, by the process of claim 1 wherein that a cleaning fluid flow is to be periodically by each bed pipeline volume difference to change.