CN116135278A - Liquid phase simulated moving bed adsorption separation system and application thereof, and method for extracting meta-xylene by mixed xylene adsorption separation - Google Patents
Liquid phase simulated moving bed adsorption separation system and application thereof, and method for extracting meta-xylene by mixed xylene adsorption separation Download PDFInfo
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- 238000001179 sorption measurement Methods 0.000 title claims abstract description 129
- 238000000926 separation method Methods 0.000 title claims abstract description 50
- IVSZLXZYQVIEFR-UHFFFAOYSA-N m-xylene Chemical group CC1=CC=CC(C)=C1 IVSZLXZYQVIEFR-UHFFFAOYSA-N 0.000 title claims abstract description 48
- 239000007791 liquid phase Substances 0.000 title claims abstract description 14
- 238000000034 method Methods 0.000 title claims abstract description 13
- 239000008096 xylene Substances 0.000 title claims abstract description 12
- CTQNGGLPUBDAKN-UHFFFAOYSA-N O-Xylene Chemical compound CC1=CC=CC=C1C CTQNGGLPUBDAKN-UHFFFAOYSA-N 0.000 title abstract description 14
- 239000000463 material Substances 0.000 claims abstract description 56
- 238000011010 flushing procedure Methods 0.000 claims abstract description 15
- 238000002156 mixing Methods 0.000 claims description 38
- 239000007788 liquid Substances 0.000 claims description 22
- 239000003463 adsorbent Substances 0.000 claims description 15
- 238000007599 discharging Methods 0.000 claims description 12
- 230000000274 adsorptive effect Effects 0.000 claims description 7
- 238000004891 communication Methods 0.000 claims description 6
- 230000000149 penetrating effect Effects 0.000 claims description 5
- 230000008569 process Effects 0.000 claims description 4
- 150000003738 xylenes Chemical class 0.000 claims description 4
- 230000000694 effects Effects 0.000 abstract description 8
- 230000007547 defect Effects 0.000 abstract description 4
- 238000009826 distribution Methods 0.000 abstract description 2
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 27
- 239000002994 raw material Substances 0.000 description 12
- 238000002347 injection Methods 0.000 description 8
- 239000007924 injection Substances 0.000 description 8
- 230000003068 static effect Effects 0.000 description 6
- 238000000605 extraction Methods 0.000 description 5
- URLKBWYHVLBVBO-UHFFFAOYSA-N Para-Xylene Chemical group CC1=CC=C(C)C=C1 URLKBWYHVLBVBO-UHFFFAOYSA-N 0.000 description 4
- 238000003795 desorption Methods 0.000 description 4
- 230000005540 biological transmission Effects 0.000 description 3
- 230000000737 periodic effect Effects 0.000 description 3
- 230000001360 synchronised effect Effects 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 230000013011 mating Effects 0.000 description 2
- 230000007246 mechanism Effects 0.000 description 2
- 239000011259 mixed solution Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 239000011148 porous material Substances 0.000 description 2
- 238000007789 sealing Methods 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 230000009471 action Effects 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000004587 chromatography analysis Methods 0.000 description 1
- 239000012141 concentrate Substances 0.000 description 1
- 238000010924 continuous production Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000004508 fractional distillation Methods 0.000 description 1
- 238000004128 high performance liquid chromatography Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000011344 liquid material Substances 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 229940078552 o-xylene Drugs 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
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- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D15/00—Separating processes involving the treatment of liquids with solid sorbents; Apparatus therefor
- B01D15/08—Selective adsorption, e.g. chromatography
- B01D15/10—Selective adsorption, e.g. chromatography characterised by constructional or operational features
- B01D15/18—Selective adsorption, e.g. chromatography characterised by constructional or operational features relating to flow patterns
- B01D15/1814—Selective adsorption, e.g. chromatography characterised by constructional or operational features relating to flow patterns recycling of the fraction to be distributed
- B01D15/1821—Simulated moving beds
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C7/00—Purification; Separation; Use of additives
- C07C7/12—Purification; Separation; Use of additives by adsorption, i.e. purification or separation of hydrocarbons with the aid of solids, e.g. with ion-exchangers
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Abstract
The invention relates to the field of liquid-phase simulated moving bed adsorption separation, and discloses a liquid-phase simulated moving bed adsorption separation system and application and a method for extracting meta-xylene by mixed xylene adsorption separation. The system comprises: m adsorption columns, n multi-channel combination valves, a circulating pump, a multi-channel logistics pipeline communicated with the multi-channel combination valves, and a circulating pipeline communicated with the circulating pump and the multi-channel combination valves; wherein at least one of the adsorption columns is disposed between two adjacent multi-channel combination valves, and the system is not provided with a flushing line; m and n are positive integers respectively, and n is more than m; wherein the volume of the circulation line is set to be equal to the actual flow volume of one of the adsorption columns. The system has compact and simple structure, and the material inlet and outlet of each adsorption column are controlled by the special distribution pipeline, so that the defects of public pipelines and flushing requirement are avoided. The system also has a virtual bed layer, can run more stably and has better separation effect.
Description
Technical Field
The invention relates to the field of adsorption separation, in particular to a liquid phase simulated moving bed adsorption separation system and application and a method for extracting meta-xylene by mixed xylene adsorption separation.
Background
The simulated moving bed is a separation apparatus for performing a separation operation using the adsorption principle. The simulated moving bed technology is used as the main representative of continuous chromatography, has the advantages of high production efficiency, less organic solvent consumption, large mass transfer driving force, convenient automatic continuous production and the like, is widely applied to the fields of petrochemical industry, food industry, pharmacy and the like, and is a complex industrial process and a nonlinear, unbalanced, non-ideal and multi-degree-of-freedom periodic process with a plurality of influencing factors.
The simulated moving bed divides the fixed adsorption bed into a plurality of sections, and the sections are filled with adsorbent. Each section is provided with an inlet and outlet pipeline, and the inlet and outlet of the pipeline is controlled by a multi-channel rotary valve. CN100453867C discloses a 36-way rotary valve for a simulated moving bed of high performance liquid chromatography, the 36-way rotary valve is connected with a stepping motor provided with a synchronous pulley through a belt, the 36-way rotary valve mainly comprises a static disc and a cover shell arranged on the static disc, a transmission shaft is arranged between the static disc and the cover shell, one end of the transmission shaft is inserted into a central hole of the static disc, the other end of the transmission shaft penetrates out of the cover shell and is provided with another synchronous pulley, and sealing rings are arranged on the circumferences of the static disc and the cover shell and are uniformly fixed; a movable disc, a driving disc, a disc spring, an adjusting cushion block and a thrust bearing are sequentially arranged between the static disc and the housing from bottom to top. The 36-way rotary valve has compact structure and small dead volume, and greatly reduces the failure rate of the simulated moving bed equipment; however, the 36-channel rotary valve is very high in cost, and because each channel needs to be flushed by pipelines when different materials are switched along with the switching of the simulated moving bed layers, a corresponding flushing system needs to be configured, the pipelines are very complex, and the operation cost is increased. In addition, the movable disc and the housing are required to ensure good sealing performance and flexible rotation, the possibility of material leakage is increased due to the contradiction, the whole simulated moving bed is stopped once leakage occurs, and the long-period operation capability of the device is reduced. In the prior art, a plurality of program control valves are adopted to control different materials to enter the adsorption tower through pipelines connected with each bed layer, and a pipeline flushing system is also required to be configured.
Thus, there is a need to provide a new simulated moving bed system and application.
Disclosure of Invention
The invention aims to overcome the defect that a simulated moving bed needs to be provided with a public pipeline and a public flushing pipeline in the prior art, and provides a liquid-phase simulated moving bed adsorption separation system and application and a method for extracting meta-xylene by mixed xylene adsorption separation.
In order to achieve the above object, a first aspect of the present invention provides a liquid phase simulated moving bed adsorption separation system, comprising: m adsorption columns, n multi-channel combination valves, a circulating pump, a multi-channel logistics pipeline communicated with the multi-channel combination valves, and a circulating pipeline communicated with the circulating pump and the multi-channel combination valves; wherein at least one of the adsorption columns is disposed between two adjacent multi-channel combination valves, and the system is not provided with a flushing line; m and n are positive integers respectively, and n is more than m; wherein the volume of the circulation line is set to be equal to the actual flow volume of one of the adsorption columns.
The second aspect of the invention provides an application of the liquid phase simulated moving bed adsorption separation system in simulated moving bed adsorption separation.
In a third aspect, the invention provides a method for the adsorptive separation of mixed xylenes to extract meta-xylene in the system provided by the invention.
Through the technical scheme, the simulated moving bed system provided by the invention can control the materials flowing in or out of each adsorption column through the multi-channel combined valve. The multi-channel combined valve with special structural design can reduce dead volume, so that the common pipeline on the existing device, and the flushing pipeline and flushing operation which are required to be arranged for overcoming the material pollution of the common pipeline are avoided in the system, and the simulated moving bed system provided by the invention has simpler structure and more convenient operation; the virtual bed layer added in the system can enable the adsorption system to run more stably and has better separation effect.
Drawings
FIG. 1 is a simulated moving bed system of one embodiment provided by the present invention;
FIG. 2 is a schematic illustration of a multi-channel combination valve according to one embodiment of the present invention;
FIG. 3 is a view in section A-A of FIG. 2;
FIG. 4 is a schematic diagram of a structure of a simulated moving bed in the prior art.
Description of the reference numerals
1-adsorption column 2-multichannel combination valve 3-circulating pump
200-valve body 201-mixing runner 202-valve core channel
203-flow channel 10-first control valve 11-first pipeline
20-second control valve 21-second line 30-third control valve
31 third line 40-fourth control valve 41-fourth line
7-material inlet and outlet pipeline group 8-rotary valve 9-adsorption tower
10-flushing line 801-first transfer line 802-second transfer line
Detailed Description
The following describes specific embodiments of the present invention in detail. It should be understood that the detailed description and specific examples, while indicating and illustrating the invention, are not intended to limit the invention.
The endpoints and any values of the ranges disclosed herein are not limited to the precise range or value, and are understood to encompass values approaching those ranges or values. For numerical ranges, one or more new numerical ranges may be found between the endpoints of each range, between the endpoint of each range and the individual point value, and between the individual point value, in combination with each other, and are to be considered as specifically disclosed herein.
In the present invention, unless otherwise indicated, terms of orientation such as "upper and lower" are used to refer generally to the upper and lower directions shown in the drawings.
In a preferred embodiment as shown in FIG. 1, a first aspect of the present invention provides a liquid phase simulated moving bed adsorptive separation system comprising: m adsorption columns 1, n multi-channel combination valves 2, a circulating pump 3, a multi-channel logistics pipeline communicated with the multi-channel combination valves 2, and a circulating pipeline communicated with the circulating pump 3 and the multi-channel combination valves 2;
wherein at least one of the adsorption columns 1 is arranged between two adjacent multi-channel combination valves 2, and the system is not provided with a flushing pipeline; m and n are positive integers respectively, and n is more than m;
wherein the volume of the circulation line is set to be equal to the actual flow volume of one of the adsorption columns.
Preferably, n-m=1. For example, m may be 10-24, and correspondingly n may be 11-25, where n-m=1, i.e. in the present invention, the number of the multi-channel combination valves 2 is one more than the number of the adsorption columns 1, as in fig. 1, from top to bottom, and the multi-channel combination valves 2 are at the uppermost and lowermost of the whole system. The actual flow volume of each of the adsorption columns 1 is equal, and in the present invention, the actual flow volume refers to the sum of the volume between the adsorbent particles packed in the adsorption column and the pore volume of the adsorbent.
In the invention, different adsorption columns 1 are communicated through different multi-channel combination valves 2, which is equivalent to arranging a control mechanism (namely the multi-channel combination valve 2) capable of distributing different logistics for each adsorption column 1, thereby improving the separation efficiency and effect. Meanwhile, different multiple multi-channel combined valves are communicated through multiple logistics pipelines. A flow line for flowing the raw material to be separated, desorbent, raffinate and extract, which is shown in the example of fig. 1, is communicated between a plurality of the multi-channel combination valves 2; wherein the extraction liquid is a stream containing the target component and the desorbent, and the raffinate is a mixture stream containing the component and the desorbent after the target component is separated from the raw material to be separated. And meanwhile, the liquid which is not discharged after the system is adsorbed and desorbed is discharged from the nth multi-channel combination valve 2 at the lowest part of the system as circulating liquid, and the circulating liquid is circulated back to the 1 st multi-channel combination valve 2 through the circulating pump 3 through the circulating pipeline. Further, a main line for flowing different streams may be provided correspondingly.
In a preferred embodiment of the present invention, a plurality of the multi-channel combination valves 2 have the same structure. Preferably, the multi-channel combination valve 2 (as shown in fig. 2 and 3, wherein fig. 3 is a view of section A-A in fig. 2) includes: a valve body 200 and a plurality of control valves provided on the valve body; wherein the valve body 200 is provided with a mixing flow passage 201 penetrating through the valve body 200 and used for communicating with the adsorption column 1; a valve core passage 202 having a plurality of valve core passages communicating with the mixing flow passage 201 vertically and penetrating to the outer wall of the valve body 200; on the side wall of each of the valve core passages 202, there is a flow passage 203 penetrating to the outer wall of the valve body.
In a preferred embodiment of the present invention, a plurality of the valve core passages 202 are preferably provided along the circumferential direction of the mixing flow path 201.
In a preferred embodiment of the present invention, it is preferable that a plurality of the valve core passages 202 are provided on the same or different levels along the central axis of the mixing flow path 201. When the valve body 200 is large enough, it is sufficient to provide all the valve core passages 202 along the circumferential direction of the mixing flow path 201, that is, a plurality of the valve core passages 202 may be provided on the same horizontal plane along the central axis of the mixing flow path 201. If the valve body 200 is small enough not to arrange all the valve core passages 202 in the circumferential direction of the mixing flow passage 201, a plurality of the valve core passages 202 may be grouped and arranged on different levels along the central axis of the mixing flow passage 201.
In a preferred embodiment of the present invention, preferably, 1 control valve is provided in each of the spool passages 202.
In a preferred embodiment of the present invention, preferably, the control valve is used to control the flow of material in the flow channel. The control valve realizes the on-off control of the flow channel 203 to the mixing flow channel 201 in the valve core channel.
In the present invention, the system may further include a control mechanism for controlling the opening and closing of the control valves included in the plurality of multi-channel combination valves 2, and the control may be implemented by program software.
In a preferred embodiment of the present invention, the flow channel 203 is preferably in communication with the pipeline for introducing or discharging different materials into or out of the mixing channel 201.
In a preferred embodiment of the present invention, the flow channel 203 is preferably disposed perpendicular to the valve core channel 202.
In the present invention, on the valve body 200 of the multi-channel combination valve 2, 1 spool channel 202, 1 control valve and 1 flow channel 203 are correspondingly provided in pairs. As shown in fig. 2 and 3, an example valve body 200 includes: and 4 spool channels, 4 control valves and 4 logistics channels are correspondingly arranged.
In a preferred embodiment of the present invention, preferably, as shown in fig. 2 and 3, the 4 flow channels include: a feedstock channel for introducing feedstock to be separated into the mixing channel, a desorbent channel for introducing desorbent into the mixing channel, a raffinate channel for discharging raffinate from the mixing channel, and a draw-off liquid channel for discharging draw-off liquid from the mixing channel.
In a preferred embodiment of the present invention, as shown in fig. 2 and 3, the 4 spool channels are preferably disposed at different levels along the circumferential direction of the mixing channel and perpendicular to each other. 4 valve core passages 202 and correspondingly 4 material flow passages 203 are arranged on the valve body 200, as shown in fig. 3. Preferably, 4 control valves are disposed on the valve body 200 and are divided into two groups of control valve groups, and two control valves in each group are disposed in a pairwise symmetrical distribution. For example, the valve body 200 is provided with a first control valve 10, a second control valve 20, a third control valve 30 and a fourth control valve 40; wherein the first control valve 10 and the second control valve 20 are arranged in a group and are symmetrically distributed in pairs; similarly, the third control valve 30 and the fourth control valve 40 are arranged in another group, and are symmetrically distributed in pairs. Further, the two groups of control valve groups are arranged on different horizontal planes and are arranged vertically. For example, as shown in fig. 2, the first control valve 10 and the second control valve 20 are on the same level, while the third control valve 30 and the fourth control valve 40 are on the other same level, the two levels being different and disposed perpendicular to each other. Correspondingly, as shown in fig. 3, the 4 valve core passages 202 are also divided into two groups, wherein the two groups are symmetrically distributed, and the two groups are not on the same horizontal plane and are arranged vertically.
In a preferred embodiment of the present invention, correspondingly, 4 lines communicating with the flow channel 203 are provided in pairs corresponding to 4 control valves. For example, as shown in fig. 2, a first line 11 is provided in pair with the first control valve 10, a second line 21 is provided in pair with the second control valve 20, a third line 31 is provided in pair with the third control valve 30, and a fourth line 41 is provided in pair with the fourth control valve 40.
In a preferred embodiment of the present invention, as shown in fig. 2 and 3, the valve body 200 preferably has 4 flow channels 203, which are a raw material channel for introducing raw material to be separated into the mixing flow channel 201, a desorbent channel for introducing desorbent into the mixing flow channel 201, a raffinate channel for discharging raffinate from the mixing flow channel 201, and a draw channel for discharging draw from the mixing flow channel 201, respectively. In connection with fig. 1, in the present invention, a first control valve 10 and a first line 11 may be used to control the introduction of the raw material to be separated in the lower portion of the multi-channel combination valve 2, a second control valve 20 and a second line 21 may be used to control the introduction of the desorbent in the lower portion of the multi-channel combination valve 2, a third control valve 30 and a third line 31 may be used to control the discharge of the raffinate in the upper portion of the multi-channel combination valve 2, and a fourth control valve 40 and a fourth line 41 may be used to control the discharge of the raffinate in the upper portion of the multi-channel combination valve 2. When the multi-channel combined valve 2 works, only one control valve controls the corresponding pipeline to be in an open state to realize feeding/discharging, and the other three control valves control the corresponding pipeline to be closed.
In a preferred embodiment of the present invention, as shown in fig. 1, preferably, the raw material channels included in the different multi-channel combination valves 2 are connected in parallel, the desorbent channels included in the different multi-channel combination valves are connected in parallel, the raffinate channels included in the different multi-channel combination valves are connected in parallel, and the extract channels included in the different multi-channel combination valves are connected in parallel. The parallel connection is realized through corresponding logistics pipelines, a material flow channel is provided, the system is constructed, and the simulated moving bed adsorption separation of the mixed material flowing into the system is realized.
In a preferred embodiment of the present invention, as shown in fig. 1, the circulation pump 3 preferably communicates the 1 st multi-channel combination valve (uppermost multi-channel combination valve in fig. 1) with the nth multi-channel combination valve (lowermost multi-channel combination valve in fig. 1) for circulating the material discharged from the mixing flow path of the nth multi-channel combination valve into the mixing flow path of the 1 st multi-channel combination valve, thereby realizing the circulation operation of the simulated moving bed. In the invention, as shown in fig. 1, the uppermost multi-channel combination valve is the 1 st multi-channel combination valve, the lowermost multi-channel combination valve is the n-th multi-channel combination valve, correspondingly, the uppermost adsorption column is the 1 st adsorption column, and the lowermost adsorption column is the m-th adsorption column. Preferably, the number of the multi-channel combination valves is one more than the number of the adsorption columns. According to the invention, the nth multi-channel combined valve which is more than one adsorption column is arranged at the lowest part in the system, so that the synchronous consistency of the time of the material flow in and out of each adsorption column in the system can be realized besides the normal operation of the adsorption separation of the simulated moving bed, the time difference between the material flow in and out of the adsorption columns caused by the circulation time of the circulating liquid when the mth adsorption column is switched with the 1 st adsorption column is eliminated, the continuity and the stability of the components of the circulating liquid are maintained, and the separation effect of the adsorption system is improved.
In a preferred embodiment of the present invention, preferably, the system is divided into a plurality of functional areas along a direction from the 1 st to the nth multi-channel combination valve; each of the functional zones includes at least one of the adsorption columns and the multi-channel combination valve. The separation device can be divided into functional areas which are the same as those of the conventional simulated moving bed used for adsorption separation, such as a desorption area, a refining area, an adsorption area and a buffer area from top to bottom. Each of the multi-channel combination valves 2 supplies or draws out a flow from or into the adsorption column 1 to which the multi-channel combination valve 2 communicates, for performing adsorption separation of different stages, to the mixing flow channel 201 under the on/off control of a control valve provided in the valve element channel 202 provided by the plurality of flow channels 202, as described above. By controlling the multi-channel combination valve 2 at different positions in the system, different materials (such as raw materials to be separated, desorbing agent, raffinate and extract) are periodically changed from top to bottom to enter and exit the multi-channel combination valve 2, so that the position of entering or exiting the adsorption column 1 is changed, adsorption and desorption are repeatedly carried out, and the purpose of continuously separating target products from the raw materials to be separated is realized.
In a preferred embodiment of the present invention, the adsorption column is preferably packed with an adsorbent. Corresponding adsorbents which can realize adsorption separation to obtain target components can be filled for different adsorption separation systems.
In a preferred embodiment of the present invention, the material flowing in and out of the adsorption column 1 passes through the mixing flow channel 201 of the multi-channel combination valve 2, and is further communicated with different flow channels 203 in the multi-channel combination valve 2; under the step control of different control valves in the multi-channel combined valve 2, the adsorption and desorption of the adsorption column 1 are realized, and different obtained products are discharged out of the liquid-phase simulated moving bed adsorption separation system. By adopting the liquid-phase simulated moving bed adsorption separation system provided by the invention, a plurality of the multichannel combined valves 2 which are arranged in a dispersing way are realized to independently provide controllable in-out logistics pipelines for each adsorption column 1, a public pipeline is not required to be arranged, a flushing pipeline and a flushing step are correspondingly omitted, and the retention of materials can be greatly reduced in the structural design of the multichannel combined valves 2.
In a preferred embodiment of the present invention, each of the multi-channel combination valves 2 concentrates the multi-channel pipeline and the corresponding control valve required for performing the adsorption separation of the simulated moving bed, and is directly arranged between different adsorption columns, so that the occupied space of the control valve and the corresponding pipeline is advantageously reduced, and the pipeline structure of the whole system is simplified.
In a specific embodiment of the invention, the system further comprises an automatic control system for controlling the material inlet and outlet of the multi-channel combined valves and realizing the periodic switching of the material inlet and outlet positions in the system so as to achieve the effect of improving the adsorption separation of the simulated moving bed.
In a particularly preferred embodiment of the present invention, as shown in FIG. 1, a simulated moving bed adsorptive separation system is provided that can be used for the separation of mixed xylenes (para-xylene, ortho-xylene, and meta-xylene). Each of the adsorption columns 1 is filled with an adsorbent for adsorbing a target product such as meta-xylene. Each multi-channel combination valve is connected with and controls four strands of materials, namely raw materials to be separated (mixed xylene), desorbent (toluene), extract (mixed solution of meta-xylene and toluene) and raffinate (mixed solution of ortho-xylene, meta-xylene and toluene) respectively.
The liquid phase simulated moving bed adsorption separation system according to the invention shown in FIG. 1, wherein F is a multi-channel combination valve according to 1 st, 2 nd and 3 … … n in the system 1 、F 2 、F 3 ……F n Corresponding to noRaw material channel D of same multichannel combined valve for introducing raw material to be separated 1 、D 2 、D 3 ……D n Corresponding to desorption channels of different multi-channel combined valves for introducing desorbent, R 1 、R 2 、R 3 ……R n Raffinate channels for discharging raffinate on different multi-channel combination valves E 1 、E 2 、E 3 ……E n The process of separating meta-xylene by mixed xylene simulated moving bed adsorption can be realized by corresponding to the extraction liquid channels for discharging the extraction liquid on different multi-channel combination valves as follows:
raw materials to be separated from F 3 Injecting into a 3 rd multi-channel combination valve 2, flowing downwards along with the circulating liquid into a 3 rd adsorption column 1 filled with adsorbent, adsorbing m-xylene components in the 3 rd adsorption column 1 by the adsorbent, and passing the non-adsorbed o-xylene and p-xylene and the original toluene in the circulating liquid through R of the 4 th multi-channel combination valve 4 Enters the raffinate header and is collected. At the same time, desorbent D is injected into the 1 st multi-channel combination valve 2 through D1, and as the circulating liquid enters the 1 st adsorption column 1, the adsorption column is filled with the adsorbent which is adsorbed with the meta-xylene adsorbed in the previous cycle, the injection of the desorbent displaces the meta-xylene adsorbed in the adsorbent, and E passes through the 2 nd multi-channel combination valve 2 And the mixture enters an extraction liquid main pipe to be collected, and the components in the extraction liquid are mixed liquid of meta-xylene and toluene. Because the boiling point difference of toluene and meta-xylene is larger, the toluene and the meta-xylene are easily separated by a fractional distillation method, and the high-purity meta-xylene and the toluene are obtained, the meta-xylene is collected as a target product, and the toluene is recycled as a desorber after being collected. The raffinate was treated in the same manner. In actual operation of the simulated moving bed, circulating liquid is formed from bottom to top by the material flow remained in each adsorption column through a circulating pump, and adsorption separation can be repeatedly carried out; four strands of materials are fed and discharged, and the four strands of materials are sequentially moved on an adsorption column of the system from top to bottom at regular time through different multi-channel combined valves, the positions of the inlet and outlet of the fed and discharged materials are continuously switched, and periodic circulation is formed along a plurality of adsorption columns, so that the purpose of continuously collecting the extracted liquid and the raffinate to achieve adsorption separation is achieved, and the aim of arranging no equipment is neededA flush line is placed.
The invention sets up the said multi-channel combination valve that is more than the number of the adsorption columns, combine and set up the circulation pipeline, volume of the circulation pump and actual logistics volume of an adsorption column (refer to the sum of the volume and pore volume of adsorbent between the adsorbent particles packed in the adsorption column) to be equal, can be referred to as the "virtual bed". In fig. 1, the total volume of the inlets of the mixing channels from the outlet of the mth adsorption column through the nth multi-channel combination valve, the circulating pump and the circulating pipeline to the 1 st multi-channel combination valve is set to be equal to the actual flow volume of one adsorption column, which is equivalent to one virtual bed layer. The time of the control material flow passing through the virtual bed layer is equal to the switching time of the adsorption columns, so that the advance (or time difference) of the material injection or discharge of the material in and out during the switching from the m adsorption column to the 1 adsorption column in the prior art can be eliminated. Because the virtual bed layer is not provided with the adsorbent, the virtual bed layer is not provided with the adsorption separation performance, in order to avoid excessive injection or discharge of the material caused by adding the material, the feeding amount of the nth multi-channel combination valve and the 1 st multi-channel combination valve is halved in a control program, namely, the injection and discharge of the material of the virtual bed layer and the 1 st adsorption column are halved.
For example, setting the switching time of each control valve in the multi-channel combination valve to be 100 seconds, and injecting half of the injection amount of the material of the conventional adsorption column into the virtual bed within the action time of 100 seconds when the system runs to the nth multi-channel combination valve for feeding; the nth multi-channel combination valve is closed in the next 100 seconds, the 1 st multi-channel combination valve is opened, the material starts to be injected into the 1 st adsorption column, and the material flow injected by the nth multi-channel combination valve in the last step just enters the 1 st adsorption column, so that the total material injection quantity of the 1 st adsorption column is unchanged, the injection time sequence is the same as that of other adsorption columns, and the defect of early injection is overcome. And in addition, when desorbent is injected, the extracting solution and the raffinate are extracted, the advance existing in the prior art can be eliminated, so that the adsorption system operates more stably, and the separation effect is better.
The arrangement of the virtual bed layer eliminates the time difference between the circulating liquid material and the material entering and exiting from other conventional adsorption columns when the m adsorption column and the 1 adsorption column are switched, is beneficial to maintaining the continuity and stability of the circulating liquid components, and is beneficial to the stable operation of the adsorption system and the improvement of the separation effect.
The second aspect of the invention provides an application of the liquid phase simulated moving bed adsorption separation system in simulated moving bed adsorption separation.
In a third aspect, the invention provides a method for the adsorptive separation of mixed xylenes to extract meta-xylene in the system provided by the invention.
According to the method of the invention, a simulated moving bed system consisting of the multi-channel combined valves and adsorption columns is adopted, for example, 15 adsorption columns are used for configuring 16 multi-channel combined valves, so as to prepare a 15+1 simulated moving bed system, the adsorption columns are filled with MX adsorbent, and the multi-channel combined valves are controlled by a program control system. The mixed xylene raw material containing 42wt% of meta-xylene is separated by the simulated moving bed, so that the meta-xylene with the purity of 99.89% is obtained, and the yield of the meta-xylene is 99%.
Whereas the simulated moving bed in the prior art, as shown in fig. 3, comprises a rotary valve 8 and an adsorption tower 9, and a mating pipeline, the adsorption tower 9 comprises a plurality of adsorption beds (i.e. adsorption columns, for example, 24 adsorption beds), and the mating pipeline at least comprises: the material inlet and outlet pipeline group 7 (including 2 material inlet pipelines and 2 material outlet pipelines), the flushing pipeline 10, the material inlet and outlet pipelines (namely, a plurality of first conveying lines 801 and second conveying lines 802 for connecting the rotary valve 8 and the adsorption tower 9, the number of the first conveying lines 801 and the second conveying lines 802 respectively correspond to that of the adsorption bed layer), the rotary valve 8 and the adsorption tower 9 realize material inlet and outlet through the material inlet and outlet pipelines, and four pipelines (for example, 2 material inlet pipelines and 2 material outlet pipelines at the same time) for simultaneously feeding and discharging materials at the same time are of the prior art and are not repeated herein. In this prior art, a plurality of common lines, such as a first line 801 and a second line 802, are provided, and when different materials are replaced, the common lines need to be flushed through the flushing line 10, which is complicated in process and increases the overall energy consumption of the device. Moreover, dead corners (e.g., pipe corners) are typically present in utility lines that are not easily flushed.
The simulated moving bed system provided by the invention comprises the multi-channel combined valve with the specific structure, no dead angle which is difficult to wash exists, and materials can directly enter the corresponding adsorption column through the mixing runner. In addition, the multichannel combination valve is provided with control pipelines for communicating different logistics, the communication adsorption columns are arranged in a dispersed manner, materials are supplied to each adsorption column to enter and exit, and each material uses a special distributing pipe, so that the defect that the materials need to be washed when the materials are switched due to the arrangement of common pipelines on the industrial device in the prior art is avoided, the common pipelines are not required to be arranged in the simulated moving bed system, the washing step of the common pipelines is omitted, the structure of the system is also saved, and the complexity of operation is reduced. In the system, compare in the multichannel combination valve that the adsorption column set up more, match circulation pipeline, circulating pump's volume with one the actual commodity circulation volume of adsorption column is equal, forms "virtual bed", when implementing the adsorption separation, can eliminate the time difference with the normal operating of adsorption column that exists when system's circulation switches, make the operation of adsorption system more steady, the separation effect is better.
The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, a number of simple variants of the technical solution of the invention are possible, including combinations of the individual technical features in any other suitable way, which simple variants and combinations should likewise be regarded as being disclosed by the invention, all falling within the scope of protection of the invention.
Claims (12)
1. A liquid phase simulated moving bed adsorptive separation system, comprising: m adsorption columns, n multi-channel combination valves, a circulating pump, a multi-channel logistics pipeline communicated with the multi-channel combination valves, and a circulating pipeline communicated with the circulating pump and the multi-channel combination valves;
wherein at least one of the adsorption columns is disposed between two adjacent multi-channel combination valves, and the system is not provided with a flushing line; m and n are positive integers respectively, and n is more than m;
wherein the volume of the circulation line is set to be equal to the actual flow volume of one of the adsorption columns.
2. The system of claim 1, wherein the multi-channel combination valve comprises: a valve body and a plurality of control valves disposed in the valve body; wherein,,
the valve body is provided with a mixing runner penetrating through the valve body and used for communicating the adsorption column; a plurality of valve core channels which are vertically communicated with the mixing flow channel and penetrate through the outer wall of the valve body; a flow passage penetrating to the outer wall of the valve body is arranged on the side wall of each valve core passage.
3. The system of claim 2, wherein a plurality of the spool channels are disposed circumferentially of the mixing flow passage;
and/or, a plurality of the valve core channels are arranged on the same or different horizontal planes along the central axis of the mixing flow channel;
and/or, 1 control valve is arranged in each valve core channel.
4. A system according to claim 2 or 3, wherein the flow channels communicate with the flow line for introducing or discharging different materials into or out of the mixing channel;
and/or the control valve is used for controlling the material flow in the material flow channel.
5. A system according to claim 2 or 3, wherein the flow channel is arranged perpendicular to the spool channel.
6. A system according to claim 2 or 3, wherein the valve body comprises: the valve core channels, the control valves and the logistics channels are respectively arranged in 4;
and/or, the 4 logistics channels comprise: a feedstock channel for introducing feedstock to be separated into the mixing channel, a desorbent channel for introducing desorbent into the mixing channel, a raffinate channel for discharging raffinate from the mixing channel, and a draw-off liquid channel for discharging draw-off liquid from the mixing channel;
and/or the 4 valve core channels are arranged on different horizontal planes along the circumferential direction of the mixing flow channel and mutually perpendicular.
7. The system of claim 6, wherein through the plurality of said flow lines, the feed channels of different ones of said multi-channel combination valves are in parallel communication, the desorbent channels of different ones of said multi-channel combination valves are in parallel communication, the raffinate channels of different ones of said multi-channel combination valves are in parallel communication, and the extract channels of different ones of said multi-channel combination valves are in parallel communication.
8. A system according to claim 2 or 3, wherein the circulation pump communicates the 1 st multi-channel combination valve with the n-th multi-channel combination valve through the circulation line, and is configured to circulate and introduce the material discharged from the mixing flow passage of the n-th multi-channel combination valve into the mixing flow passage of the 1 st multi-channel combination valve as circulation liquid.
9. The system of claim 1, wherein the system is divided into a plurality of functional zones along a direction from the 1 st to the nth multi-channel combination valve; each of the functional zones includes at least one of the adsorption columns and the multi-channel combination valve.
10. The system of claim 1, wherein the adsorption column is packed with adsorbent.
11. Use of a system according to any one of claims 1-10 in simulated moving bed adsorptive separation.
12. A process for the adsorptive separation of mixed xylenes to extract meta-xylene in the system of any of claims 1-10.
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