CN113952756B - Method for concentrating heavy components in NMP waste liquid - Google Patents
Method for concentrating heavy components in NMP waste liquid Download PDFInfo
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- CN113952756B CN113952756B CN202111570914.8A CN202111570914A CN113952756B CN 113952756 B CN113952756 B CN 113952756B CN 202111570914 A CN202111570914 A CN 202111570914A CN 113952756 B CN113952756 B CN 113952756B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
- B01D3/14—Fractional distillation or use of a fractionation or rectification column
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
- B01D3/14—Fractional distillation or use of a fractionation or rectification column
- B01D3/32—Other features of fractionating columns ; Constructional details of fractionating columns not provided for in groups B01D3/16 - B01D3/30
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D207/00—Heterocyclic compounds containing five-membered rings not condensed with other rings, with one nitrogen atom as the only ring hetero atom
- C07D207/02—Heterocyclic compounds containing five-membered rings not condensed with other rings, with one nitrogen atom as the only ring hetero atom with only hydrogen or carbon atoms directly attached to the ring nitrogen atom
- C07D207/18—Heterocyclic compounds containing five-membered rings not condensed with other rings, with one nitrogen atom as the only ring hetero atom with only hydrogen or carbon atoms directly attached to the ring nitrogen atom having one double bond between ring members or between a ring member and a non-ring member
- C07D207/22—Heterocyclic compounds containing five-membered rings not condensed with other rings, with one nitrogen atom as the only ring hetero atom with only hydrogen or carbon atoms directly attached to the ring nitrogen atom having one double bond between ring members or between a ring member and a non-ring member with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached to ring carbon atoms
- C07D207/24—Oxygen or sulfur atoms
- C07D207/26—2-Pyrrolidones
- C07D207/263—2-Pyrrolidones with only hydrogen atoms or radicals containing only hydrogen and carbon atoms directly attached to other ring carbon atoms
- C07D207/267—2-Pyrrolidones with only hydrogen atoms or radicals containing only hydrogen and carbon atoms directly attached to other ring carbon atoms with only hydrogen atoms or radicals containing only hydrogen and carbon atoms directly attached to the ring nitrogen atom
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Abstract
The invention discloses a method for concentrating heavy components in NMP waste liquid. According to the characteristics of the heavy components in the NMP waste liquid, the heavy components generated by the NMP waste liquid recovery device are further concentrated, the yield of dangerous waste is reduced, and the NMP solvent is recovered. The problems of polymerization, coking, blockage, large tower pressure drop and the like of heavy components are avoided, and the device can stably run for a long period.
Description
Technical Field
The invention relates to the technical field of hazardous waste treatment, in particular to an NMP waste liquid recovery device mainly used in industries such as lithium batteries, smart phones and tablet computers, and particularly relates to a method for concentrating heavy components in NMP waste liquid.
Background
Can produce NMP (N-methyl pyrrolidone) waste liquid in the lithium cell production, the NMP waste liquid gets into NMP and retrieves the purification device in order to retrieve the NMP solvent, the NMP is retrieved the purification device and is adopted conventional precision to fractionate, membrane recovery, techniques such as hypergravity fractionation can retrieve most NMP solvent, can remain a small amount of NMP waste liquid heavy ends simultaneously, this NMP waste liquid heavy ends belongs to dangerous waste and needs to be sent to special unit and handle, in order to reduce the output of NMP waste liquid heavy ends, retrieve the NMP solvent simultaneously, need adopt various measures to further concentrated the processing to NMP waste liquid heavy ends. The heavy components in the NMP waste liquid have two treatment modes at present: firstly, directly delivering the waste to a hazardous waste treatment unit, and paying; second, self-processing, which has two ways at present: 1) adopts a batch rectifying tower, and 2) adopts a continuous rectifying tower, and the two types of towers belong to the conventional rectifying technology. Heavy metal and various high molecular polymers are contained in heavy components of NMP waste liquid, further polymerization and coking are easy to occur at high temperature, coked particles are carried into a filler of a precision forging section along with gas phase, the filler is easily coked and blocked, frequent cleaning of equipment is needed, labor intensity is increased, and long-period stable operation cannot be achieved.
The invention provides a novel method for concentrating heavy components in NMP waste liquid, which avoids the problems of polymerization, coking, blockage, large tower pressure drop and the like of the heavy components and enables the device to stably run for a long period.
Disclosure of Invention
The invention aims to provide a method for concentrating heavy components in NMP waste liquid, which is used for further concentrating the heavy components generated by an NMP waste liquid recovery device, reducing the yield of dangerous waste and simultaneously recovering an NMP solvent.
In order to achieve the purpose, the invention adopts the following technical scheme:
the invention provides a method for concentrating heavy components in NMP waste liquid, which comprises the following steps:
mixing an NMP waste liquid heavy component raw material with a path of tower bottom heavy component from the bottom of a fractionating tower, heating to a temperature required by the process (the typical operating temperature is 80-140 ℃, and is not more than 150 ℃), mixing with a path of circulating cooling washing liquid from the upper part of the fractionating tower, and then feeding into a feeding section in the middle of the fractionating tower;
the fractionating tower comprises a circulating cooling washing section, a feeding section, a stripping section and a bottom circulating stirring filter from top to bottom;
the circulating cooling washing liquid is led out from the bottom of the circulating cooling washing section and divided into two paths; cooling one path to the temperature required by the process, and filtering and returning the path to the top of the fractionating tower; the other path of the mixed material is mixed with the heated mixed material of the heavy component raw material of the NMP waste liquid and the heavy component at the bottom of the tower, and then enters a feeding section in the middle of the fractionating tower;
heavy components at the bottom of the tower are led out from the bottom of the fractionating tower and are divided into two paths after being filtered; one path is mixed with the raw material of the heavy components of the NMP waste liquid; cooling the other path to the temperature required by delivery, then dividing the cooled path into two paths, returning the other path to the bottom of the fractionating tower to control the temperature of the bottom of the fractionating tower to be at a lower value (the recommended temperature of the bottom of the fractionating tower is not more than 150 ℃, generally between 90 and 140 ℃), stirring the bottom of the fractionating tower to avoid high-temperature coking at the bottom of the fractionating tower, and outputting the other path as a concentrated heavy component;
and (4) leading out gas at the top of the fractionating tower, condensing and cooling the gas, and recovering NMP recovery liquid.
According to the method of the invention, preferably, the top gas of the fractionating tower is led out, condensed and cooled, and then enters a top NMP collecting tank of the fractionating tower, the top NMP collecting tank of the fractionating tower is connected with a vacuumizing device to pump out the non-condensable gas, and the lower the top pressure of the fractionating tower is, the better the pressure is (the typical operation pressure is 0.1-10 KPa (absolute pressure)).
According to the method, preferably, a stripping section below a feeding section of the fractionating tower is provided with a plurality of layers of herringbone baffles, preferably 4-10 layers, and tower internals such as fixed valves, sieve plates and the like can also be adopted, and the inclined installation is recommended.
According to the method, preferably, one path of heavy components at the bottom of the tower is mixed with the raw materials of the heavy components in the NMP waste liquid under the control of the second flow control valve group, the flow rate of the path is controlled by a large circulation amount, and the preferable circulation amount needs to reach the spraying density of 2-10 m in the tower3/(m2·h)。
According to the method provided by the invention, preferably, the other path of the heavy components at the bottom of the tower is returned to the bottom of the fractionating tower under the control of the third flow control valve group so as to control the temperature of the bottom of the fractionating tower to be not more than 150 ℃, preferably 90-140 ℃.
According to the method, preferably, one path of the circulating cooling washing liquid is cooled to the temperature required by the process (preferably 25-90 ℃ and can be specifically and optimally designed according to the temperature at the top of the tower) under the cascade control of the first flow control valve group and the temperature at the top of the tower, filtered and returned to the top of the fractionating tower, and the temperature at the top of the fractionating tower is controlled to the value required by the process, preferably 30-130 ℃, and can be specifically and optimally designed according to the operating pressure of the tower.
According to the method, preferably, the other path of the circulating cooling washing liquid is mixed with the heated mixed material of the NMP waste liquid heavy component raw material and the tower bottom heavy component under the control of a hydraulic control valve group, and then enters a feeding section in the middle of the fractionating tower;
according to the method, preferably, heavy components at the bottom of the tower are filtered and led out of the bottom of the fractionating tower, so that impurities in a system are filtered, and the operation period of equipment is prolonged.
According to the method of the present invention, preferably, the feeding section of the fractionating tower is provided with a tubular distributor, and the nozzles of the tubular distributor are wear resistant nozzles.
According to the method of the invention, preferably, one or more than two sections of grid packing are arranged in the circulating cooling washing section of the fractionating tower, a distributor is arranged at the upper part of the grid packing, and an oil accumulation tank is arranged at the lower part of the grid packing; and the circulating cooling washing liquid is led out from the oil accumulation tank and circularly returns to the distributor.
More preferably, the height of each section of the grid filler is 1.5-5 m, and multiple sections of the filler can be arranged according to needs.
In another aspect, the present invention provides a system for concentrating heavy components in NMP waste liquid, which is used to implement the above method, and the system includes: the device comprises a fractionating tower, a feeding pipeline, an NMP recovery pipeline, a circulating cooling washing liquid pipeline, a tower bottom heavy component pipeline, a concentrated heavy component pipeline, a fractionating tower top condenser, a fractionating tower top NMP collecting tank, an NMP recovery liquid pump, a circulating cooling washing liquid pump, a circulating washing liquid cooler, a heater, a concentrated liquid cooler and a fractionating tower bottom pump;
the fractionating tower comprises a circulating cooling washing section, a feeding section, a stripping section and a bottom circulating stirring filter from top to bottom;
the incoming material pipeline is combined with the first branch of the tower bottom heavy component pipeline, passes through the heater, is combined with a branch of the circulating cooling washing liquid pipeline, and is connected to the feeding section of the fractionating tower;
the NMP recovery pipeline is led out from an outlet at the top of the fractionating tower and is sequentially provided with a condenser at the top of the fractionating tower, an NMP collecting tank at the top of the fractionating tower and an NMP recovery liquid pump;
the circulating cooling washing liquid pipeline is led out from the bottom of a circulating cooling washing section of the fractionating tower and circularly returns to the top of the circulating cooling washing section; the circulating cooling washing liquid pump and the circulating washing liquid cooler are sequentially arranged on the circulating cooling washing liquid pump; the circulating cooling washing liquid pipeline is divided into a branch between the circulating cooling washing liquid pump and the circulating washing liquid cooler and is combined with the incoming material pipeline passing through the heater;
the tower bottom heavy component pipeline is led out from a tower bottom outlet of the fractionating tower and circularly returns to the tower bottom of the fractionating tower, and the fractionating tower bottom pump and the concentrated solution cooler are sequentially arranged on the tower bottom heavy component pipeline; the bottom heavy component pipeline leads out a first branch between the fractionating tower bottom pump and the concentrated liquid cooler to be combined with the feed pipeline, and leads out a second branch after the concentrated liquid cooler to be the concentrated heavy component pipeline.
The material supply pipeline is used for inputting an NMP waste liquid heavy component raw material into the system, one path of tower bottom heavy component conveyed by a first branch of the tower bottom heavy component pipeline is mixed with the NMP waste liquid heavy component raw material, the mixture is heated by a heater to a temperature required by the process (the typical operating temperature is 80-140 ℃ and is not more than 150 ℃), the mixture is mixed with one path of circulating cooling washing liquid conveyed by the circulating cooling washing liquid pipeline, and then a feeding section connected to the fractionating tower is used as a fractionating tower feeding section.
An NMP recovery pipeline is led out from an outlet at the top of the fractionating tower to output gas at the top of the fractionating tower, the gas is condensed and cooled by a condenser at the top of the fractionating tower and then enters an NMP collecting tank at the top of the fractionating tower, and then NMP recovery liquid is recovered.
A circulating cooling washing liquid pipeline is led out from the bottom of a circulating cooling washing section of the fractionating tower, and circulating cooling washing liquid is pumped out by a circulating cooling washing liquid pump and is divided into two paths; one path is cooled to the temperature required by the process by a circulating washing liquid cooler and then returns to the top of the fractionating tower; the other path is combined with the incoming material pipeline passing through the heater and then enters the feeding section at the middle part of the fractionating tower.
A tower bottom heavy component pipeline is led out from a tower bottom outlet of the fractionating tower, and tower bottom heavy components are pumped out by a fractionating tower bottom pump and divided into two paths; one path (a first branch) is combined with an incoming material pipeline and is mixed with an NMP waste liquid heavy component raw material; and the other path is cooled to the temperature required by delivery and then divided into two paths, wherein one path returns to the bottom of the fractionating tower to control the temperature of the bottom of the fractionating tower to be at a lower value (the recommended temperature of the bottom of the tower is not more than 150 ℃, generally 90-140 ℃), the bottom of the fractionating tower is stirred to avoid high-temperature coking at the bottom of the fractionating tower, and the other path (the second path) is used as a concentrated heavy component pipeline to output concentrated heavy components.
According to the system of the invention, preferably, the NMP collecting tank at the top of the fractionating tower is connected with a vacuumizing device, the non-condensable gas in the NMP collecting tank is pumped out, and the lower the pressure at the top of the fractionating tower is, the better the pressure is (the typical operation pressure is 0.1-10 KPa (absolute pressure)).
According to the system of the present invention, preferably, the circulating cooling washing liquid line is further provided with a first filter before returning to the top of the circulating cooling washing section.
According to the system of the present invention, preferably, the bottom heavy component line is provided with a second filter at the outlet end of the fractionation column bottom pump.
According to the system of the present invention, preferably, the feeding section of the fractionating tower is provided with a tubular distributor, and the nozzles of the tubular distributor are wear resistant nozzles.
According to the system, preferably, the stripping section of the fractionating tower is provided with a plurality of layers of herringbone baffles; preferably, 4-10 layers of herringbone baffles are arranged.
According to the system of the invention, preferably, a third filter is arranged inside the tower bottom outlet of the fractionating tower, so that impurities in the system are filtered out, and the operation period of the equipment is prolonged.
According to the system of the invention, preferably, one or more than two sections of grid packing are arranged in the circulating cooling washing section of the fractionating tower, a distributor is arranged at the upper part of the grid packing, and an oil accumulation tank is arranged at the lower part of the grid packing; and the circulating cooling washing liquid pipeline is led out from the oil accumulating tank and circularly returns to the distributor. More preferably, the height of each section of the grid filler is 1.5-5 m, and multiple sections of the filler can be arranged according to needs. The feeding material contains solid impurities, is easy to carry, and adopts a grating filler with large flux to avoid the solid impurities carried to block the filler.
According to the system of the present invention, preferably, the system comprises a control unit comprising: the system comprises a first flow control valve group, a second flow control valve group, a third flow control valve group and a hydraulic control valve group;
the first flow control valve group is arranged on the back of the circulating cooling washing liquid pipeline, the second flow control valve group is arranged on the first branch of the tower bottom heavy component pipeline, and the third flow control valve group is arranged in front of the tower bottom heavy component pipeline returning to the fractionating tower; the hydraulic control valve group is arranged between the oil accumulation tank and the circulating cooling washing liquid pipeline branch.
And under the cascade control of the first flow control valve group and the temperature of the tower top, the circulating cooling washing liquid returned to the fractionating tower by the circulating cooling washing liquid pipeline is cooled to the temperature required by the process (preferably 25-90 ℃, and the specific optimization design can be carried out according to the temperature of the tower top), and is returned to the tower top of the fractionating tower, the temperature of the tower top of the fractionating tower is controlled to the value required by the process, preferably 30-130 ℃, and the temperature can be specifically optimized and designed according to the operation pressure of the tower.
And the circulating cooling washing liquid led out by the branch of the circulating cooling washing liquid pipeline is mixed with the heated mixed material of the NMP waste liquid heavy component raw material and the tower bottom heavy component under the control of a hydraulic control valve group, and then enters a feeding section in the middle of the fractionating tower.
The tower bottom heavy component of the first branch of the tower bottom heavy component pipeline is mixed with the NMP waste liquid heavy component raw material under the control of the second flow control valve group, the flow of the branch is controlled by a large circulation amount, and the optimal circulation amount needs to reach the spraying density of 2-10 m in the tower3/(m2H). In order to prevent coking and accelerate the removal of NMP in heavy components, large circulation control is required. If the circulation quantity is too low, the plate is easy to dry, coke and NMP are not easy to separate.
And returning the tower bottom heavy component in the tower bottom heavy component pipeline to the tower bottom of the fractionating tower under the control of a third flow control valve group so as to control the tower bottom temperature of the fractionating tower to be not more than 150 ℃, preferably 90-140 ℃.
The fractionating tower is different from the conventional rectifying tower in that a reboiler is arranged at the bottom of the conventional rectifying tower, and materials at the bottom of the tower enter the reboiler (by pump circulation or thermosiphon circulation), are heated by the reboiler and then return to the bottom of the tower. The tower bottom material is pumped out by a pump (thermal siphon circulation is not used) and heated, and then returns to the middle position of the tower (the flow of a path of the first branch is controlled by large circulation), namely, the material enters a middle feeding section after being heated by a heater, and a tower plate (stripping section) is arranged below the feeding section. The advantage that the bottom material does not return to the bottom but mostly to the middle: the returning to the bottom of the tower is only equivalent to 1 theoretical plate, and the middle position is returned, so that a plurality of layers of tower trays can be arranged below the returning port, and the effect of a plurality of theoretical plates is realized; the pump circulation is used instead of thermosiphon, and the thermosiphon pipeline has a low point and is easy to deposit. Only part of the tower bottom materials are cooled and then returned to the tower bottom, so that the temperature of the tower bottom of the fractionating tower is controlled to be at a lower value (the recommended tower bottom temperature is not more than 150 ℃, generally 90-140 ℃), and the tower bottom is stirred, so that the high-temperature coking of the tower bottom of the fractionating tower is avoided. The invention achieves the purpose of prolonging the long-term operation of the tower through the 3 actions (cooling, stirring and filtering) at the tower bottom, and the conventional rectification technology is stopped and cleaned when the operation is often less than 2 months because of the coking and blockage of the tower bottom. The present invention is expected to meet operating cycles of 1 year or more.
In the system and the method, the heat extraction technology above the feeding section is as follows: the conventional heat extraction method at the top of the rectification tower is that the overhead gas enters a reflux tank after being condensed, and then one path of overhead gas is pumped out and returned to the top of the rectification tower, and the other path of overhead gas is sent out. The invention adopts the cooling of the circulating cooling material, namely a strand of material is extracted from the lateral line to be used as the circulating cooling washing liquid, and the circulating cooling washing liquid is cooled by a circulating washing liquid cooler and filtered by a filter and then returns to the tower top; the liquid material is cooled and the amount of this material is relatively large. The benefits of the heat removal technology above the feed section of the present invention over conventional heat removal for cooling gaseous materials include:
1) after heat is extracted by the heat extraction technology, the material at the top of the tower is directly used as a product after being cooled, the flow of the gas at the top of the tower is small, the pressure drop of the gas at the top of the tower passing through a condenser at the top of the fractionating tower is small, and the fractionating tower is operated under negative pressure, so that the tower can be operated under lower pressure (the lower the pressure is, the more the operation of the device is facilitated);
2) the equipment arrangement of the liquid heat exchanger (circulating washing liquid cooler) can be placed at any position, and the conventional cooling of the gas material has requirements on the installation height of the equipment;
3) the scheme has high flexibility and saves investment.
Drawings
FIG. 1 is a schematic diagram of a system and process for concentrating heavy components of an NMP waste solution according to a preferred embodiment of the present invention.
Description of reference numerals:
c1 fractionating tower
100 incoming material pipeline
200 NMP recovery line
300 circulating cooling washing liquid pipeline
400 bottoms heavies line
500 concentrate heavies line
E1 fractionating tower top condenser
D1 fractionating tower top NMP collecting tank
P1 NMP recycling liquid pump
P2 circulating cooling washing liquid pump
E2 circulating washing liquid cooler
E3 heater
E4 concentrated solution cooler
P3 fractionating tower bottom pump
SR1 first filter
SR2 second filter
SR3 third filter
FC1 first flow control valve set
FC2 second flow control valve set
FC3 third flow control valve set
LC1 pilot operated valve set.
Detailed Description
In order to more clearly illustrate the invention, the invention is further described below in connection with preferred embodiments. It is to be understood by persons skilled in the art that the following detailed description is illustrative and not restrictive, and is not to be taken as limiting the scope of the invention.
The present invention provides a preferred embodiment herein, as shown in fig. 1, a system for concentrating heavy components of NMP waste liquid, the system comprising: a fractionating column C1, a feed line 100, an NMP recovery line 200, a recycle cooling wash liquid line 300, a bottoms heavies line 400, a concentrated heavies line 500, a fractionation overhead condenser E1, a fractionation overhead NMP holding tank D1, an NMP recovery liquid pump P1, a recycle cooling wash liquid pump P2, a recycle wash liquid cooler E2, a heater E3, a concentrate cooler E4, and a fractionation column bottoms pump P3.
The fractionating tower C1 comprises a circulating cooling washing section, a feeding section, a stripping section and a bottom circulating stirring filter from top to bottom.
The feed line 100 is combined with the first branch of the bottom heavies line 400, passed through the heater E3, combined with a branch of the recycle cooled wash liquid line 300, and connected to the feed section of the fractionation column C1.
The NMP recovery pipeline 200 is led out from the top outlet of the fractionating tower C1 and is sequentially provided with the fractionating tower top condenser E1, a fractionating tower top NMP collecting tank D1 and an NMP recovery liquid pump P1;
the recycle cooling wash liquid line 300 leads from the bottom of the recycle cooling wash section of the fractionation column C1 and is recycled back to the top of the recycle cooling wash section; the circulating cooling washing liquid pump P2 and the circulating washing liquid cooler E2 are arranged on the washing machine in sequence; the recycle cooling washing liquid line 300 branches off between the recycle cooling washing liquid pump P2 and the recycle washing liquid cooler E2, and merges with the incoming line 100 after passing through the heater E3.
The bottom heavy component line 400 is led out from the bottom outlet of the fractionating tower C1 and is circulated back to the bottom of the fractionating tower C1, and the fractionating tower bottom pump P3 and the concentrated liquid cooler E4 are sequentially arranged on the bottom heavy component line; the bottoms heavies line 400 exits a first branch between the fractionation tower bottoms pump P3 and the concentrate cooler E4 to merge with the incoming line 100 and a second branch after the concentrate cooler E4 to the concentrate line 500.
When the system works, an NMP waste liquid heavy component raw material is input into the system through an incoming material pipeline 100, one path of bottom heavy component conveyed by a first path of a bottom heavy component pipeline 400 is mixed with the NMP waste liquid heavy component raw material, the mixture is heated to a temperature required by the process (the typical operation temperature is 80-140 ℃ and is not more than 150 ℃) through a heater E3, then the mixture is mixed with one path of circulating cooling washing liquid conveyed by a circulating cooling washing liquid pipeline 300, and then a feeding section connected to a fractionating tower C1 feeds the fractionating tower C1.
An NMP recovery pipeline 200 is led out from the top outlet of the fractionating tower C1 to output top gas, the top gas is condensed and cooled by a fractionating tower top condenser E1 and then enters a fractionating tower top NMP collecting tank D1, and then NMP recovery liquid is recovered.
A circulating cooling washing liquid pipeline 300 is led out from the bottom of a circulating cooling washing section of the fractionating tower C1, and circulating cooling washing liquid is pumped out by a circulating cooling washing liquid pump P2 and divided into two paths; one path is cooled to the temperature required by the process by a circulating washing liquid cooler E2 and then returns to the top of the fractionating tower; the other path is combined with a feed line 100 passing through the heater E3 and then enters a feed section at the middle part of the fractionating tower.
A tower bottom heavy component pipeline 400 is led out from a tower bottom outlet of the fractionating tower C1, and a fractionating tower bottom pump P3 is used for pumping out the tower bottom heavy components and dividing the heavy components into two paths; one path (a first path) is combined with an incoming material pipeline 100 and is mixed with the raw material of the heavy components of the NMP waste liquid; and the other path is cooled to the temperature required by delivery and then divided into two paths, wherein one path returns to the bottom of the fractionating tower to control the temperature of the bottom of the fractionating tower to be at a lower value (the recommended temperature of the bottom of the fractionating tower is not more than 150 ℃, generally at 90-140 ℃), the bottom of the fractionating tower is stirred to avoid high-temperature coking at the bottom of the fractionating tower, and the other path (the second path) is used as a concentrated heavy component pipeline 500 to output concentrated heavy components.
According to the system of the present invention, preferably, the NMP collection tank D1 at the top of the fractionating tower is connected to a vacuum extractor, and the non-condensable gas in the NMP collection tank is extracted, and the lower the pressure at the top of the fractionating tower is, the better the pressure is (typically, the operating pressure is 0.1 to 10KPa (absolute)).
In the preferred embodiment, the recirculating cooling scrubbing liquid line 300 is also provided with a first filter SR1 before returning to the top of the recirculating cooling scrubbing section. The bottom heavies line 400 is provided with a second filter SR2 at the outlet end of the fractionation column bottom pump P3.
In the preferred embodiment, the feed section of the fractionation column C1 is provided with a tubular distributor, and the nozzles of the tubular distributor are attrition resistant nozzles. Because the feed contains solid impurities and is easy to wear and block, the distributor arranged here is a pipe type distributor and provided with a spray head, and a conventional groove type distributor (easy to block) is not used; the conventional stainless steel (stainless steel is not wear-resistant) is not adopted, and the wear-resistant material is adopted.
In the preferred embodiment, the stripping section of the fractionating column C1 is provided with a plurality of layers of herringbone baffles; preferably, 4-10 layers of herringbone baffles are arranged. Heavy components contain impurities and are dirty, so that conventional tower plates and fillers are not arranged in a stripping section below a feed, and the tower plates are obliquely arranged to avoid the impurities from being deposited on the tower plates.
In the preferred embodiment, a third filter SR3 is arranged inside the bottom outlet of the fractionating tower C1, so as to filter impurities in the system and prolong the operation period of the equipment. The third filter SR3 is coarse filtration, and a finer filter SR2 is also arranged on the heavy component pipeline 400 at the bottom of the tower, so that impurities in the system can be filtered timely, and the operation period of the equipment can be prolonged.
In the preferred embodiment, one or more than two sections of grid packing are arranged in the circulating cooling washing section of the fractionating tower C1, the upper part of the grid packing is provided with a distributor, and the lower part of the grid packing is provided with an oil accumulation tank; the circulating cooling wash line 300 leads from the sump and circulates back to the distributor. More preferably, the height of each section of the grid filler is 1.5-5 m, and multiple sections of the filler can be arranged according to needs. The feeding material contains solid impurities, is easy to carry, and adopts a grating filler with large flux to avoid the solid impurities carried to block the filler.
In this preferred embodiment, the system comprises a control unit comprising: a first flow control valve group FC1, a second flow control valve group FC2, a third flow control valve group FC3, and a pilot control valve group LC 1;
the first set of flow control valves FC1 is disposed on the circulating cooling wash liquor line 300 after it branches, the second set of flow control valves FC2 is disposed on the first branch of the bottom heavies line 400, and the third set of flow control valves FC3 is disposed before the bottom heavies line 400 returns to the bottom of the fractionation column C1; the hydraulic control valve group LC1 is arranged between the oil accumulation tank and the branch of the circulating cooling washing liquid pipeline 300.
The circulating cooling washing liquid returned to the fractionating tower by the circulating cooling washing liquid pipeline 300 is cooled to the temperature required by the process (preferably 25-90 ℃ and can be specifically and optimally designed according to the temperature at the top of the tower) under the cascade control of the first flow control valve group FC1 and the temperature at the top of the tower, and is returned to the top of the fractionating tower, the temperature at the top of the fractionating tower is controlled to the value required by the process, preferably 30-130 ℃, and the temperature can be specifically and optimally designed according to the operating pressure of the tower.
The circulating cooling washing liquid led out from the branch of the circulating cooling washing liquid pipeline 300 is mixed with the heated mixed material of the NMP waste liquid heavy component raw material and the tower bottom heavy component under the control of a hydraulic control valve group LC1, and then enters a feeding section in the middle of the fractionating tower.
The heavy component at the bottom of the first branch of the heavy component pipeline 400 at the bottom of the tower is mixed with the heavy component raw material of the NMP waste liquid under the control of a second flow control valve group FC2, the flow rate of the branch is controlled by a large circulation amount, and the optimal circulation amount needs to reach the spraying density of 2-10 m in the tower3/(m2H). In order to prevent coking and accelerate the removal of NMP in heavy components, large circulation quantity control is needed, and when the circulation quantity is too low, the plate is easy to dry and coke, and the NMP is not easy to remove.
The heavy component at the bottom of the fractionating tower C1 in the heavy component at the bottom of the tower line 400 is returned to the bottom of the fractionating tower under the control of a third flow control valve group FC3 so as to control the temperature of the bottom of the fractionating tower to be not more than 150 ℃, preferably 90-140 ℃.
In the preferred embodiment, the method for concentrating heavy components in NMP waste liquid comprises the following processes:
the NMP waste liquid heavy component raw material is mixed with a path of tower bottom heavy component from the tower bottom of a fractionating tower, heated to the temperature required by the process (the typical operating temperature is 80-140 ℃, and is not more than 150 ℃), mixed with a path of circulating cooling washing liquid from the upper part of the fractionating tower, and then fed into a feeding section in the middle of the fractionating tower.
The circulating cooling washing liquid is led out from the bottom of the circulating cooling washing section and divided into two paths; cooling one path to the temperature required by the process, and filtering and returning the path to the top of the fractionating tower; and the other path of the mixed material is mixed with the heated mixed material of the heavy component raw material of the NMP waste liquid and the heavy component at the bottom of the tower, and then enters a feeding section in the middle of the fractionating tower.
Heavy components at the bottom of the tower are led out from the bottom of the fractionating tower and are divided into two paths after being filtered; one path is mixed with the raw material of the heavy components of the NMP waste liquid; and the other path is cooled to the temperature required by delivery and then divided into two paths, wherein one path returns to the bottom of the fractionating tower to control the temperature of the bottom of the fractionating tower to be at a lower value (the recommended temperature of the bottom of the fractionating tower is not more than 150 ℃, generally 90-140 ℃), the bottom of the fractionating tower is stirred to avoid high-temperature coking at the bottom of the fractionating tower, and the other path is output as a concentrated heavy component.
And (4) leading out gas at the top of the fractionating tower, condensing and cooling the gas, and recovering NMP recovery liquid.
In the preferred embodiment, the top gas of the fractionating tower is led out, condensed and cooled, and then enters a top NMP collecting tank of the fractionating tower, the top NMP collecting tank of the fractionating tower is connected with a vacuumizing device, the non-condensable gas in the top gas of the fractionating tower is pumped out, and the lower the top pressure of the fractionating tower is, the better the top pressure of the fractionating tower is (the typical operation pressure is 0.1-10 KPa (absolute pressure)).
In the preferred embodiment, one path of heavy components at the bottom of the tower is mixed with the raw material of the heavy components in the NMP waste liquid under the control of the second flow control valve group, the flow rate of the path is controlled by a large circulation amount, and the preferred circulation amount needs to reach the spraying density of 2-10 m in the tower3/(m2·h)。
In the preferred embodiment, the other path of the heavy component at the bottom of the tower returns to the bottom of the fractionating tower under the control of the third flow control valve group so as to control the temperature of the bottom of the fractionating tower to be not more than 150 ℃, preferably 90-140 ℃.
In the preferred embodiment, one path of the circulating cooling washing liquid is cooled to the temperature required by the process (preferably 25-90 ℃ and can be specifically and optimally designed according to the temperature at the top of the tower) under the cascade control of the first flow control valve group and the temperature at the top of the tower, filtered and returned to the top of the fractionating tower, and the temperature at the top of the fractionating tower is controlled to the value required by the process, preferably 30-130 ℃, and can be specifically and optimally designed according to the operating pressure of the tower.
In the preferred embodiment, the other path of the circulating cooling washing liquid is mixed with the heated mixed material of the NMP waste liquid heavy component raw material and the tower bottom heavy component under the control of a hydraulic control valve group, and then enters the feeding section in the middle of the fractionating tower.
In the preferred embodiment, heavy components at the bottom of the tower are filtered and led out of the bottom of the fractionating tower, so that impurities in the system are filtered out, and the operation period of the equipment is prolonged.
In the preferred embodiment, the feed section of the fractionation column is provided with a tubular distributor, and the nozzles of the tubular distributor are attrition resistant nozzles.
In the preferred embodiment, one or more than two sections of grid packing are arranged in the circulating cooling washing section of the fractionating tower, a distributor is arranged at the upper part of the grid packing, and an oil accumulation tank is arranged at the lower part of the grid packing; and the circulating cooling washing liquid is led out from the oil accumulation tank and circularly returns to the distributor. More preferably, the height of each section of the grid filler is 1.5-5 m, and multiple sections of the filler can be arranged according to needs.
It should be understood that the above-mentioned embodiments of the present invention are only examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention, and it will be obvious to those skilled in the art that other variations or modifications may be made on the basis of the above description, and all embodiments may not be exhaustive, and all obvious variations or modifications may be included within the scope of the present invention.
Claims (10)
1. A method for concentrating heavy components in NMP waste liquid is characterized by comprising the following steps:
mixing an NMP waste liquid heavy component raw material with a path of tower bottom heavy component from the bottom of a fractionating tower, heating to the temperature required by the process, mixing with a path of circulating cooling washing liquid from the upper part of the fractionating tower, and then entering a feeding section in the middle of the fractionating tower;
the fractionating tower comprises a circulating cooling washing section, a feeding section, a stripping section and a bottom circulating stirring filter from top to bottom;
the circulating cooling washing liquid is led out from the bottom of the circulating cooling washing section and divided into two paths; cooling one path to the temperature required by the process, and filtering and returning the path to the top of the fractionating tower; the other path of the mixed material is mixed with the heated mixed material of the heavy component raw material of the NMP waste liquid and the heavy component at the bottom of the tower, and then enters a feeding section in the middle of the fractionating tower;
heavy components at the bottom of the tower are led out from the bottom of the fractionating tower and are divided into two paths after being filtered; one path is mixed with the raw material of the heavy components of the NMP waste liquid; the other path is cooled to the temperature required by delivery and then divided into two paths, one path returns to the bottom of the fractionating tower to control the temperature of the bottom of the fractionating tower to be a lower value, and meanwhile, the bottom of the fractionating tower is stirred to avoid high-temperature coking at the bottom of the fractionating tower, and the other path is output as a concentrated heavy component;
and (4) leading out gas at the top of the fractionating tower, condensing and cooling the gas, and recovering NMP recovery liquid.
2. The method of claim 1, wherein the fractionation tower overhead gas is condensed and cooled and then introduced into a fractionation tower overhead NMP collection tank, and wherein the fractionation tower overhead NMP collection tank is connected to a vacuum extractor.
3. The method of claim 1, wherein the stripping section below the feed section of the fractionation column is provided with a plurality of layers of chevron baffles.
4. The method according to claim 1, characterized in that one path of heavy components at the bottom of the tower is mixed with the raw material of the heavy components in the NMP waste liquid under the control of a second flow control valve group, the flow rate of the path is controlled by a large circulation amount, and the circulation amount needs to reach the spraying density of 2-10 m in the tower3/(m2·h)。
5. The method of claim 4 wherein the other of the bottoms heavies is returned to the bottom of the fractionation tower under the control of a third set of flow control valves to control the temperature of the bottom of the fractionation tower at no greater than 150 ℃.
6. The method as claimed in claim 1, wherein one path of the circulating cooling washing liquid is cooled to the temperature required by the process under the cascade control of the first flow control valve group and the temperature of the top of the tower, and then filtered and returned to the top of the fractionating tower, so as to control the temperature of the top of the fractionating tower to the value required by the process.
7. The method as claimed in claim 6, wherein the other path of the circulating cooling washing liquid is mixed with the heated mixed material of the NMP waste liquid heavy component raw material and the tower bottom heavy component under the control of a hydraulic control valve group, and then enters the feeding section in the middle of the fractionating tower.
8. The method of claim 1 wherein the bottoms heavies are filtered and directed to the bottom of the fractionation column.
9. The method of claim 1, wherein the feed section of the fractionation column is provided with a tubular distributor and the nozzles of the tubular distributor are attrition resistant nozzles.
10. The method according to claim 1, characterized in that one or more than two sections of grid packing are arranged in the circulating cooling washing section of the fractionating tower, a distributor is arranged at the upper part of the grid packing, and an oil accumulation tank is arranged at the lower part of the grid packing; and the circulating cooling washing liquid is led out from the oil accumulation tank and circularly returns to the distributor.
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| US9181500B2 (en) * | 2014-03-25 | 2015-11-10 | Uop Llc | Process and apparatus for recycling cracked hydrocarbons |
| US10876050B2 (en) * | 2019-03-01 | 2020-12-29 | Uop Llc | Process for producing diesel fuel from a biorenewable feed |
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| CN102250635A (en) * | 2010-05-21 | 2011-11-23 | 中国石油化工集团公司 | Method and device for removing salt for fractionate tower |
| CN203462006U (en) * | 2013-09-23 | 2014-03-05 | 博英睿科(北京)科技有限公司 | Device for preventing delayed coking fractionating tower from coking |
| CN105566028A (en) * | 2014-10-13 | 2016-05-11 | 中国石油化工股份有限公司 | Separation system and separation method for mother liquor of polyolefin catalyst |
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Denomination of invention: A Method for Concentrating the Recombinant Fraction of NMP Waste Liquid Effective date of registration: 20230531 Granted publication date: 20220225 Pledgee: Tianjin SME Credit Financing Guarantee Co.,Ltd. Pledgor: Tianjin Muhua Qingyan Technology Co.,Ltd. Registration number: Y2023120000029 |
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