CN210481246U

CN210481246U - NMP solvent recovery system in acetylene preparation process by partial oxidation of natural gas

Info

Publication number: CN210481246U
Application number: CN201920201934.XU
Authority: CN
Inventors: 柯月亮; 陈林; 曹宝山; 周美均; 王萍萍
Original assignee: Chongqing Chuanwei Technology Co ltd; China Petroleum and Chemical Corp; Sinopec Chongqing Chuanwei Chemical Co Ltd
Current assignee: Chongqing Chuanwei Technology Co ltd; China Petroleum and Chemical Corp; Sinopec Chongqing Chuanwei Chemical Co Ltd
Priority date: 2019-02-15
Filing date: 2019-02-15
Publication date: 2020-05-08
Anticipated expiration: 2029-02-15

Abstract

The utility model belongs to the technical field of realize the separation through the evaporation that makes a thin layer liquid and the surface that has heated contact, NMP solvent recovery system in the concretely relates to natural gas partial oxidation system acetylene technology, it is provided with pre-heater 1, pre-heater 1 intercommunication film evaporator 3, this film evaporator 3 is connected with condenser 2, 3 intercommunication dry distillation sediment collection tank 4 of film evaporator, dry distillation sediment collection tank 4 sets up in the below of film evaporator 3, and this dry distillation sediment collection tank 4 communicates with dry distillation sediment storage tank 5, and this dry distillation sediment storage tank 5 is in the below of dry distillation sediment collection tank 4, 2 bottoms of condenser are connected with solvent recovery tank 6, condenser 2 and dry distillation sediment collection tank 4 communicate with vacuum pump 7 respectively. The system improves the recovery rate of the NMP solvent; the blockage problem caused by crystallization and coking is avoided; the problem of excessive VOCs emission in the production field can be effectively controlled; the automation level of the NMP solvent recovery device is improved.

Description

NMP solvent recovery system in acetylene preparation process by partial oxidation of natural gas

Technical Field

The utility model belongs to the technical field of the evaporation that contacts through making a thin layer liquid and heated surface realizes the separation, concretely relates to NMP solvent recovery system in natural gas partial oxidation system acetylene technology.

Background

Acetylene is a very important organic chemical raw material, and is widely used in the fields of metal processing, welding, cutting and the like, and the preparation of chemical products such as ethylene, vinyl chloride, trichloroethylene, vinyl acetate, acrylonitrile, polyacrylonitrile, 1, 4-butanediol and the like ("the acetylene is newly developed in organic synthetic chemistry", step winning, China chemical trade, No. 7, No. 22, No. 103, published Japanese 2015, 12 and 31 days; "research progress of acetylene preparation by low-carbon alkane pyrolysis by thermal plasma", Subaogen and the like, chemical reaction engineering and processes, No. 29, No. 3, No. 230, 236 pages, and published Japanese 2013, 06 and 30 months). The preparation method of acetylene mainly comprises a non-catalytic partial oxidation method, an electric arc method, a plasma method and the like, wherein the electric arc method is eliminated due to high energy consumption, the plasma method is still in a test stage (the current state of research of natural gas acetylene, thinking, angry, vinylon communication, No. 33, No. 2, No. 15-20, No. 2013, No. 12, No. 31 in 2013), the power consumption is high, the requirements on equipment are harsh, the method is difficult to popularize and apply so far, and the non-catalytic partial oxidation method is a main method for producing acetylene.

In the prior art, the main structure and the main production process of a production device adopted in the process of preparing acetylene by non-catalytic partial oxidation of natural gas are as follows: the natural gas pipeline and the oxygen pipeline are respectively connected with a gas heater, natural gas and oxygen are respectively preheated to 600-650 ℃, the natural gas is firstly introduced into the acetylene reaction furnace, when the temperature of the natural gas reaches a set value, an auxiliary oxygen regulating valve of the reaction furnace is opened, and an ignition gun is operated to ignite; introducing oxygen for oxygen feeding after ignition is successful, wherein reaction gas consisting of natural gas and oxygen generates partial oxidation reaction in a reaction chamber of an acetylene furnace, cooling after reaction for a few milliseconds to finish the reaction, and hydrocarbon is partially oxidized and cracked into a cracked gas mixture containing acetylene, carbon monoxide, carbon dioxide, hydrogen, carbon black and other components; and (3) after the cracked gas mixture from the acetylene reaction furnace passes through the lower section of the cooling tower, the electric dust remover and the upper section of the cooling tower, further cooling and washing carbon black in the cracked gas mixture, and then entering a concentration system through a compressor to obtain acetylene and synthesis gas products. Water containing carbon black discharged from the bottoms of an acetylene furnace, a cooling tower and an electric dust remover enters a collecting pipe, a small amount of gas is removed through flash evaporation in a first-stage sieve plate degassing tank, the water enters an open carbon black water tank for separating carbon black from water, the obtained clean water is partially returned to the acetylene furnace to be used as quenching water, and one part of the clean water is sent to a cooling water tower for cooling and then sent to the cooling tower, the electric dust remover and a concentration device to be used as spray cooling water (as shown in figure 1).

In the process of preparing acetylene by partial oxidation of natural gas, N-methyl pyrrolidone (NMP) solvent is widely used in the concentration process of cracking gas. Under the condition that the relative pressure is 0.8-1.0MPa, the cracking gas is in countercurrent contact with NMP sprayed in sections, wherein substances such as high alkyne and acetylene which are easily soluble components are absorbed by the NMP. The carrier gas NMP constantly presses the tower and the vacuum tower, and the acetylene component and the higher alkyne component are respectively resolved. During the absorption and analysis of NMP, some of the easily crystallized and easily polymerized components such as benzene, naphthalene and higher alkyne are accumulated in NMP, which affects the absorption capacity of the circulating solvent on one hand, and is easily crystallized and polymerized to form scale on the other hand, thereby blocking pipelines and fillers. In the prior art, part of circulating solvent is taken out and is primarily concentrated by a continuous flash tank, and the bottom NMP solvent is separated by a suspension separator to obtain the concentrated NMP solvent containing the polymer. And (3) the concentrated NMP solvent enters a solvent storage tank, and then is added into a dry distillation tank in batches from the storage tank, so that the clean recovered NMP solvent is obtained after dry distillation. The heavy component dry distillation slag is manually drawn out of the dry distillation tank and transferred to a storage tank. The dry distillation residues contain a small amount of NMP solvent, and the NMP solvent in the dry distillation residues needs to be recovered, otherwise, the loss of the NMP solvent is large.

The existing batch dry distillation system (as shown in figure 2) has low thermal efficiency and long distillation time. Because the tank body of the dry distillation tank is heated by the coil, the heating temperature of the tank bottom and the tank wall cannot be accurately controlled, local heating is uneven, dry distillation slag is easy to coke and form blocks, and manual slag removal is needed. The manual slag removal has high labor intensity, a large amount of malodorous VOCs gas is discharged, the environment is polluted, and serious occupational health hazards are easily caused. In addition, the dry distillation residue contains about 29% (mass content) of the NMP solvent, and the NMP solvent in the dry distillation residue needs to be recovered, otherwise, a large amount of NMP solvent is lost. The thermal efficiency of the dry distillation equipment is about 55 percent, the thermal efficiency is relatively low, the distillation time reaches 22 hours per tank, and the running period is long.

Chinese patent publication No. CN1044474780A discloses a method for continuously recovering NMP solvent from a polyphenylene sulfide production apparatus, which comprises the steps of preheating raw materials, feeding the preheated raw materials into a rectifying tower C-101, extracting wastewater from the top of the tower, forcibly circulating concentrated bottom liquid at the bottom of the tower by a centrifugal pump, dehydrating part of solid products by a centrifugal machine, discharging the dehydrated part of the solid products out of a battery compartment, feeding supernatant mother liquor into the top of the rectifying tower C-102 to separate p-dichlorobenzene, feeding the bottom liquid into the rectifying tower C-103, further cooling and extracting the NMP solvent evaporated from the top of the tower after heat exchange with feed liquid, and extracting a chloride solution of the NMP solvent from the bottom of the tower by a forced circulation pump. The method has the advantages of more refined separation of components in the raw materials, higher separation purity of the product and better operability. However, in the case of an NMP material containing a large amount of heat-sensitive components and easily crystallized components, only a part of the NMP solvent can be separated, and the NMP amount gradually decreases and the solubility of the relatively less volatile matter relatively continuously increases with the amount of the NMP solvent below the feed inlet of the rectifying tower, so that the easily crystallized matter is more easily precipitated. As the concentration of the high polymer increases and the temperature of the bottom increases, the high polymer is more easily polymerized, and part of the polymer can be attached to the inner wall of the tower and the surface of the packing, so that the polymer blocks the packing and pipelines, which is proved in the practice of acetylene concentration production operation for many years; and the other part of the crystallized substances and the polymers are discharged in a liquid form through the tower bottom, and because a large amount of NMP solvent is contained, the NMP recovery rate is obviously low, and the subsequent treatment cost is larger. The high-grade alkyne is the main reason for causing the pipeline blockage of the acetylene concentration system of the acetylene preparation device from natural gas, the high-grade alkyne gas is mainly rich in methylacetylene, vinyl acetylene, butadiene, diacetylene and other components with the trace of more than C4, and due to the existence of unsaturated bonds of each alkyne component, under certain temperature and pressure and in the presence of trace oxygen, peroxide, etc. in the system, free radical polymerization is easy to occur, the generated free radical generates macromolecular polymer through the processes of chain initiation, chain growth and chain termination, and a large amount of polymers are easy to deposit and pollute in the high-grade alkyne pipeline and block the equipment pipeline, so that the safe and stable long-period operation of the concentration system is influenced (shallow analysis of blockage reasons of the high-grade alkyne pipeline of the acetylene concentration device, whole soldiers thanks, natural gas chemical industry, volume 36 in 2011, pages 34 to 37, and published day 2011, 12 months and 31 days).

Aiming at the NMP solvent containing heat-sensitive components, how to realize automatic continuous production, how to improve the thermal efficiency in the dry distillation process, how to prevent the residue from being coked in large blocks and realize automatic slag discharge in the treatment process have important significance for the solvent recovery of the natural gas acetylene concentration device and the energy consumption of a circulating system, automatic upgrade and treatment of industrial solid waste.

SUMMERY OF THE UTILITY MODEL

In view of this, the utility model aims at providing a NMP solvent recovery system, this system can realize having improved the rate of recovery to the recovery that contains easy crystallization, the NMP solvent of heat sensitive component, and can avoid the jam problem that crystallization, coking formed, simultaneously, does not need artifical scarfing cinder, improves NMP solvent recovery unit automation level, can not cause polluted environment and occupational health harm.

In order to achieve the above purpose, the technical scheme of the utility model is that:

the NMP solvent recovery system is provided with a preheater 1, the top of the preheater 1 is provided with a liquid phase input end and a liquid phase output end, the liquid phase output end is communicated with the thin film evaporator 3 through the liquid phase input end at the top of the thin film evaporator 3, the thin film evaporator 3 is connected with the condenser 2 through a gas phase output end at the top, a slag discharging port is arranged at the bottom of the thin film evaporator 3, the slag discharge port is communicated with a dry distillation slag collecting tank 4 through a slag discharge pipe, the dry distillation slag collecting tank 4 is arranged below the thin film evaporator 3, the bottom of the dry distillation residue collecting tank 4 is communicated with a dry distillation residue storage tank 5 through a residue discharge pipe, the dry distillation residue storage tank 5 is arranged below the dry distillation residue collecting tank 4, the bottom of the condenser 2 is provided with a liquid discharge port, the liquid outlet is connected with a solvent recovery tank 6 through a downcomer, and the condenser 2 and the dry distillation residue collection tank 4 are respectively connected with a vacuum pump 7 through pipelines.

The system can realize the recovery of the NMP solvent containing the easily crystallized and thermosensitive components, and improves the recovery rate.

The system can avoid the blockage problem caused by crystallization and coking.

This system does not need artifical scarfing cinder, improves NMP solvent recovery unit automation level, can not cause polluted environment and occupational health harm.

In order to further improve the rate of recovery of the NMP solvent, the solvent recovery tank 6 is provided with a vertically arranged partition plate, the partition plate divides the inner cavity of the tank body into a storage area and a down-flow area, and a gap is reserved between the top of the partition plate and the top of the tank body.

In order to further improve the recovery rate of the NMP solvent, one end of the downcomer is connected with a liquid outlet of the condenser 2, the other end of the downcomer is immersed below the liquid level of a liquid descending area of the solvent recovery tank 6, and the vertical distance between the two ends of the downcomer is more than 10 m.

In order to further improve the recovery rate of the NMP solvent, the heating medium is steam or heat conducting oil.

In order to further improve the recovery rate of the NMP solvent, a vacuum control valve 8 is arranged on a pipeline connecting the vacuum pump 7 and the dry distillation residue collection tank 4.

In order to further increase the recovery rate of the NMP solvent, a pressure regulating valve 9 is provided in a line connecting the vacuum pump 7 and the vertical gas condenser 2.

In order to further improve the recovery rate of the NMP solvent, the preheater 1 is a tubular preheater, and the inner wall of the preheater 1 is polished.

In order to further improve the recovery rate of the NMP solvent, a flow control valve 10 is provided on a liquid phase inlet line of the preheater 1.

In order to further improve the recovery rate of the NMP solvent, the thin film evaporator 3 is a wiped film evaporator.

In order to further improve the recovery rate of the NMP solvent, the wiper blade of the thin film evaporator 3 is a movable type wiper blade.

In order to further improve the recovery rate of the NMP solvent, electromagnetic valves matched with each other are arranged at the bottoms of the thin film evaporator 3 and the dry distillation residue collecting tank 4.

In order to further improve the recovery rate of the NMP solvent, the bottom of the dry distillation residue collection tank 4 is provided with a nitrogen flow rate regulating valve 13.

In order to further improve the recovery rate of the NMP solvent, the condenser 2 is a vertical shell-and-tube condenser.

In order to further improve the recovery rate of the NMP solvent, the slag discharging pipe is provided with a slag discharging valve 11, and the slag discharging pipe is provided with a slag discharging valve 12.

The nitrogen flow regulating valve 13 is connected with a nitrogen pipe network through a pipeline. When discharging slag, a slag discharging valve 11 on the slag discharging pipe is closed, a vacuum control valve 8 is closed, a nitrogen flow regulating valve 13 is opened, the dry distillation slag collecting tank recovers positive pressure, a slag discharging valve 12 on the slag discharging pipe is opened, and dry distillation slag is discharged into a dry distillation slag storage tank 5 due to gravity. And after the dry distillation slag is discharged, the slag discharging valve 12 on the slag discharging pipe is closed, the nitrogen flow regulating valve 13 is closed, the vacuum control valve 8 is opened, when the pressure reaches the pressure of the thin film evaporator 3, the vacuum control valve 8 is closed, the slag discharging valve 11 on the slag discharging pipe is opened, and the primary slag discharging process is completed. Through the arrangement, the automatic slag discharging function under continuous operation is realized.

The beneficial effects of the utility model reside in that:

the utility model discloses can realize the recovery to the NMP solvent that contains easy crystallization, heat sensitive component, improve the rate of recovery.

The utility model discloses can avoid the jam problem that crystallization, coking formed, realize automatic row's sediment, improve the device automation level.

The utility model discloses do not need artifical scarfing cinder, improved NMP recovery unit's automation level.

The utility model discloses VOCs who can the effective control production site arranges excess problem scattered, can not cause environmental pollution and occupational health harm.

Drawings

FIG. 1 is a flow diagram of an acetylene concentration system;

FIG. 2 is a schematic view of a batch retort system;

fig. 3 is a thin film evaporator system of example 1, in which 1 is a preheater, 2 is a condenser, 3 is a thin film evaporator, 31 is a thin film evaporator motor, 4 is a retort slag collection tank, 5 is a retort slag storage tank, 6 is a solvent recovery tank, 7 is a vacuum pump, 71 is a vacuum pump motor, 8 is a vacuum control valve, 9 is a pressure regulating valve, 10 is an NMP flow regulating valve, 11 is a slag discharge valve, 12 is a slag discharge valve, 13 is a nitrogen flow regulating valve, No.5 is nitrogen gas at a pressure of 0.5MPa, Iw33 is circulating cooling water, S1.0 is heat transfer oil or steam at a pressure of 1MPa, NMP is a raw NMP liquid, S0.6 is heat transfer oil or steam at a pressure of 0.6MPa, and C0.6 is a condensate.

Detailed Description

The examples are provided for the purpose of better illustration of the present invention, but are not intended to limit the present invention to the examples. Therefore, those skilled in the art should appreciate that they can readily use the disclosed conception and specific embodiments as a basis for modifying or modifying other embodiments without departing from the scope of the present invention.

Example 1

Taking NMP stock solution (from a concentration process in the process of preparing acetylene by partial oxidation of natural gas) to carry out component detection, wherein the result is shown in Table 1;

wherein, the MP content is detected according to the general method for measuring the shading rate of chemical reagents GB/T614-2006;

the method for detecting the total content of the thermosensitive polymer is a gravimetric method, and specifically comprises the following steps: heating and evaporating the solvent with the mass M under the condition of gas inerting until the measured mass (the mass is N) is obtained, wherein the total content of the thermosensitive polymer is N/M x 100 percent;

the water content is detected according to GB/T6283-2008 determination of water content in chemical products;

the content detection of acetylene, methylacetylene, diacetylene, vinylacetylene, divinylacetylene and benzene is carried out by adopting a conventional chromatographic analysis method.

The NMP stock solution is treated by adopting a system shown in the attached figure 3, and the system comprises a preheater 1, a condenser 2, a thin film evaporator 3, a dry distillation residue collecting tank 4, a dry distillation residue storage tank 5, a solvent recovery tank 6 and a vacuum pump 7. The preheater 1 is a shell and tube preheater, the condenser 2 is a vertical shell and tube condenser, the film evaporator 3 is a scraper type film evaporator, and scrapers of the scraper type film evaporator are movable scrapers.

NMP solvent gets into preheater 1 from the inlet of preheater 1, and this inlet is provided with the control valve, and shell and tube preheater 1 adopts steam or conduction oil heating. The inner wall of the preheater 1 is subjected to polishing treatment. The NMP solvent enters the thin film evaporator 3 after being heated by the tubular preheater 1, and the heated NMP solvent realizes the separation of the gas phase NMP solvent and the solid phase dry distillation slag in the thin film evaporator 3.

The vacuum pump 7 is respectively connected with the condenser 2 and the dry distillation residue collecting tank 4 through pipelines, a vacuum control valve 8 is arranged on the pipeline connecting the vacuum pump 7 and the dry distillation residue collecting tank 4, a pressure regulating valve 9 is arranged on the pipeline connecting the vacuum pump 7 and the condenser 2, an NMP flow regulating valve 10 is arranged on a liquid inlet pipeline of the preheater 1, electromagnetic valves which are matched with each other are arranged at the bottoms of the thin film evaporator 3 and the dry distillation residue collecting tank 4, and a nitrogen flow regulating valve 13 is arranged at the bottom of the dry distillation residue collecting tank 4;

the gaseous phase NMP solvent enters into the condenser 2 through a pipeline arranged on the top of the thin film evaporator 3, the bottom of the condenser 2 is provided with a liquid outlet, and the liquid outlet is connected with the solvent recovery tank 6 through a downcomer.

The liquid phase NMP solvent after the condensation falls into the down-flow district of solvent recovery jar 6 through the downcomer by gravity (solvent recovery jar 6 is provided with the baffle of vertical setting, separates jar internal chamber for storage area and down-flow district with the baffle, leaves the clearance between baffle top and the jar body top).

One end of the downcomer is connected with a liquid outlet of the gas condenser 2, the other end of the downcomer is immersed below the liquid level of a liquid descending area of the solvent recovery tank 6, and the vertical distance between the two ends of the downcomer is more than 10 m.

The bottom of the thin film evaporator 3 is provided with a slag discharge hole which is communicated with a dry distillation slag collecting tank 4 through a slag discharge pipe, and the dry distillation slag collecting tank 4 is arranged below the thin film evaporator 3. The bottom of the dry distillation residue collecting tank 4 is communicated with the dry distillation residue storage tank 5 through a residue discharge pipe, and the dry distillation residue storage tank 5 is arranged below the dry distillation residue collecting tank 4. The slag discharging pipe is provided with a slag discharging valve 11, and the slag discharging pipe is provided with a slag discharging valve 12.

The nitrogen flow regulating valve 13 is connected with a nitrogen pipe network through a pipeline. When discharging slag, a slag discharging valve 11 on the slag discharging pipe is closed, a vacuum control valve 8 is closed, a nitrogen flow regulating valve 13 is opened, the dry distillation slag collecting tank recovers positive pressure, a slag discharging valve 12 on the slag discharging pipe is opened, and dry distillation slag is discharged into a dry distillation slag storage tank 5 due to gravity. And after the dry distillation slag is discharged, closing a slag discharging valve 12 on the slag discharging pipe, closing a nitrogen flow regulating valve 13, opening a vacuum control valve 8, closing the vacuum control valve 8 when the pressure reaches the pressure of the thin film evaporator, and opening a slag discharging valve 11 on the slag discharging pipe to finish a slag discharging process. Through the arrangement, the automatic deslagging function of the film evaporator under continuous operation is realized.

The specific process comprises the following steps: adding NMP stock solution into a storage tank before a pump, adjusting a control valve on a shell and tube preheater 1, and controlling the feeding amount to be 0.3m³And h, introducing the solvent into the thin film evaporator 3 after being preheated to 99 ℃ by the tubular preheater 1 (before starting the thin film evaporator 3, adding the NMP solvent to a falling liquid zone of the solvent recovery tank 6 until overflowing). The pressure of the pressure regulating valve 9 is 1.1 to 1.2KPa (absolute pressure) by regulating the temperature of the thin film evaporator 3 at 170 ℃. The slag discharging valve 11 on the slag discharging pipe is opened, and the slag on the slag discharging pipe is dischargedValve 12 is closed and nitrogen flow valve 13 is closed. The solvent recovery tank 6 is filled to overflow in the downcomer zone. After 60 minutes, the dry distillation collection tank discharges slag. And (3) starting the dry distillation slag collecting tank 4 to discharge slag, closing a slag discharge valve 11, automatically closing a vacuum control valve 8, filling low-pressure nitrogen into the system through a nitrogen flow regulating valve 13 to recover the positive pressure of the dry distillation slag collecting tank 4, automatically opening a slag discharge valve 12 on a slag discharge pipe, and discharging the bottom dry distillation slag material into a closed dry distillation slag storage tank 5. And after the dry distillation slag is discharged, automatically closing a slag discharging valve 12 on the slag discharging pipe, closing a nitrogen flow regulating valve 13, slowly opening a valve position by a pressure regulating valve 8, regulating the vacuum degree of the dry distillation slag collecting tank 4, closing a vacuum control valve 8 when the vacuum degree reaches the system pressure of the thin film evaporator, and automatically opening a slag discharging valve 11 on a slag discharging pipe to finish a slag discharging process.

TABLE 1 NMP stock solution composition test results

Detecting items	The result of the detection
		NMP	96% (by mass)
Heat-sensitive polymer	2.01% (by mass)
		Water (W)	0.77% (by mass)
Acetylene	8mg/L
		Methylacetylene	20mg/L
Diacetylenes	25mg/L
		Vinyl acetylene	15mg/L
Divinylacetylene	27mg/L
		Benzene and its derivatives	1.9mg/L

Comparative example 1

The NMP stock solution (same as example 1) was treated, specifically: introducing NMP stock solution into a solvent storage tank, adding the NMP stock solution into a dry distillation tank in batches from the storage tank, and feeding the NMP stock solution into the dry distillation tank at a feeding amount of 4m³The retort is carried out under the conditions of the dry distillation temperature of 170 ℃, the dry distillation time of 22h and the dry distillation pressure of 1.1-1.2KPa (absolute pressure).

Performance detection

The results of detecting the residual rate of NMP in the dry distillation residues obtained by the treatments of example 1 and comparative example 1, the state of the dry distillation residues and the content of volatile organic compounds (VOCs for short in english) in the ambient air are shown in table 1;

wherein, the NMP content in the dry distillation slag is detected according to the GB/T614-2006 chemical reagent shading rate determination general method;

the detection method of the dry distillation slag state is visual observation;

the detection method of the content of VOCs in the ambient air adopts a portable VOCs detector for field detection.

Table 2 results of performance testing

Origin of origin	Residual ratio of NMP/%)	Dry residue state	VOCs content/ppm
				Example 1	12.5	In the form of sheet	<5
Comparative example 1	29	Coking into cake	1200

As can be seen from tables 1 and 2, the system of example 1 can avoid the problem of clogging due to crystallization and coking, and can recover NMP solvent containing easily crystallized and heat-sensitive components, thereby increasing the recovery rate by 56.8% relatively.

As is clear from tables 1 and 2, the dry slag treated in example 1 did not cake as compared with comparative example 1. Therefore, the system of the utility model can avoid the blockage problem caused by crystallization and coking, and the residue can be discharged smoothly automatically from the dry distillation slag. Therefore, the method disclosed by the invention can avoid the blockage problem caused by crystallization and coking, and effectively improve the automation degree of the dry distillation device.

As is clear from tables 1 and 2, the residual ratio of NMP in the dry residue treated in example 1 was remarkably reduced as compared with that in comparative example 1; and the content of VOCs in the ambient air is significantly reduced. From this it proves, the utility model discloses a NMP solvent can effectively be retrieved to the system, and the VOCs who can the effective control production field arranges the excess problem scattered, has solved the occupational health hidden danger that manual slag removal process exists.

Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.

Claims

The NMP solvent recovery system is characterized in that a preheater (1) is arranged, the preheater (1) is communicated with a thin film evaporator (3), the thin film evaporator (3) is connected with a condenser (2), the thin film evaporator (3) is communicated with a dry distillation residue collecting tank (4), the dry distillation residue collecting tank (4) is arranged below the thin film evaporator (3), the dry distillation residue collecting tank (4) is communicated with a dry distillation residue storage tank (5), the dry distillation residue storage tank (5) is arranged below the dry distillation residue collecting tank (4), the bottom of the condenser (2) is connected with a solvent recovery tank (6), and the condenser (2) and the dry distillation residue collecting tank (4) are respectively communicated with a vacuum pump (7).
2. The NMP solvent recovery system according to claim 1, characterized in that the solvent recovery tank (6) is provided with a vertically arranged partition plate, the partition plate divides the tank inner cavity into a storage area and a down-flow area, and a gap is left between the top of the partition plate and the top of the tank.
3. The NMP solvent recovery system according to claim 1 or 2, wherein a vacuum control valve (8) is provided on a line connecting the vacuum pump (7) and the dry distillation residue collection tank (4).
4. The NMP solvent recovery system according to claim 1 or 2, characterized in that a pressure regulating valve (9) is provided on a line connecting the vacuum pump (7) and the vertical gas condenser (2).
5. A solvent recovery system for NMP according to claim 3, characterized in that a pressure regulating valve (9) is provided on the line connecting the vacuum pump (7) and the vertical gas condenser (2).
6. The NMP solvent recovery system according to claim 1, 2 or 5, wherein the preheater (1) is a shell and tube preheater, and the inner wall of the preheater (1) is polished.
7. A solvent recovery system for NMP according to claim 3, characterized in that the preheater (1) is a shell and tube preheater and the inner wall of the preheater (1) is polished.
8. The NMP solvent recovery system according to claim 1, 2, 5 or 7, characterized in that a flow regulating valve (10) is provided on a liquid phase inlet line of the preheater (1).
9. A NMP solvent recovery system according to claim 3, characterized in that a flow regulating valve (10) is provided on the liquid phase inlet line of the preheater (1).
10. The NMP solvent recovery system according to claim 4, wherein a flow regulating valve (10) is provided on a liquid phase inlet line of the preheater (1).
11. The NMP solvent recovery system according to claim 6, wherein a flow regulating valve (10) is provided on a liquid phase inlet line of the preheater (1).
12. A NMP solvent recovery system according to claim 1, 2, 5, 7, 9, 10 or 11, characterized in that the thin film evaporator (3) is a wiped film evaporator.
13. A NMP solvent recovery system according to claim 3, characterized in that the thin film evaporator (3) is a wiped film evaporator.
14. A NMP solvent recovery system according to claim 4, wherein the thin film evaporator (3) is a wiped film evaporator.
15. A NMP solvent recovery system according to claim 6, wherein the thin film evaporator (3) is a wiped film evaporator.
16. A NMP solvent recovery system according to claim 8, wherein the thin film evaporator (3) is a wiped film evaporator.
17. The NMP solvent recovery system according to claim 12, characterized in that the wiper blade of the thin film evaporator (3) is a movable wiper blade.
18. The NMP solvent recovery system according to any one of claims 13 to 17, characterized in that the wiper blades of the thin film evaporator (3) are movable wiper blades.
19. A solvent recovery system for NMP according to claim 1, 2, 5, 7, 9, 10, 11, 13, 14, 15, 16 or 17, characterized in that the bottoms of the thin film evaporator (3) and the dry distillation residue collection tank (4) are provided with electromagnetic valves fitted to each other.
20. A solvent recovery system for NMP according to claim 3, characterized in that the bottoms of the thin film evaporator (3) and the dry distillation residue collection tank (4) are provided with electromagnetic valves fitted to each other.
21. A solvent recovery system for NMP according to claim 4, characterized in that the bottom of the thin film evaporator (3) and the dry distillation residue collection tank (4) are provided with electromagnetic valves fitted to each other.
22. A solvent recovery system for NMP according to claim 6, characterized in that the bottom of the thin film evaporator (3) and the dry distillation residue collection tank (4) are provided with electromagnetic valves fitted to each other.
23. A solvent recovery system for NMP according to claim 8, characterized in that the bottom of the thin film evaporator (3) and the dry distillation residue collection tank (4) are provided with electromagnetic valves fitted to each other.
24. A solvent recovery system for NMP according to claim 12, characterized in that the bottoms of the thin film evaporator (3) and the dry distillation residue collection tank (4) are provided with electromagnetic valves fitted to each other.
25. A solvent recovery system for NMP according to claim 18, characterized in that the bottoms of the thin film evaporator (3) and the dry distillation residue collection tank (4) are provided with electromagnetic valves fitted to each other.
26. The NMP solvent recovery system according to claim 1, 2, 5, 7, 9, 10, 11, 13, 14, 15, 16, 17, 20, 21, 22, 23, 24 or 25, characterized in that the bottom of the dry residue collection tank (4) is provided with a nitrogen flow rate regulating valve (13).
27. The NMP solvent recovery system according to claim 3, wherein the bottom of the dry residue collection tank (4) is provided with a nitrogen flow rate regulating valve (13).
28. The NMP solvent recovery system according to claim 4, wherein the bottom of the dry residue collection tank (4) is provided with a nitrogen flow rate regulating valve (13).
29. The NMP solvent recovery system according to claim 6, wherein the bottom of the dry residue collection tank (4) is provided with a nitrogen flow rate regulating valve (13).
30. The NMP solvent recovery system according to claim 8, wherein the bottom of the dry residue collection tank (4) is provided with a nitrogen flow rate regulating valve (13).
31. The NMP solvent recovery system according to claim 12, characterized in that the bottom of the dry residue collection tank (4) is provided with a nitrogen flow rate regulation valve (13).
32. The NMP solvent recovery system according to claim 18, characterized in that the bottom of the dry residue collection tank (4) is provided with a nitrogen flow rate regulating valve (13).
33. The NMP solvent recovery system according to claim 19, characterized in that the bottom of the dry residue collection tank (4) is provided with a nitrogen flow rate regulating valve (13).
34. A NMP solvent recovery system in accordance with claim 1, 2, 5, 7, 9, 10, 11, 13, 14, 15, 16, 17, 20, 21, 22, 23, 24, 25, 27, 29, 30, 31, 32 or 33 characterized in that the condenser (2) is a vertical shell and tube condenser.
35. A NMP solvent recovery system according to claim 3, characterized in that the condenser (2) is a vertical shell and tube condenser.
36. A NMP solvent recovery system according to claim 4, wherein the condenser (2) is a vertical shell and tube condenser.
37. A NMP solvent recovery system according to claim 6, wherein the condenser (2) is a vertical shell and tube condenser.
38. The NMP solvent recovery system according to claim 8, characterized in that the condenser (2) is a vertical shell and tube condenser.
39. A NMP solvent recovery system according to claim 12, characterized in that the condenser (2) is a vertical shell and tube condenser.
40. A NMP solvent recovery system according to claim 18, characterized in that the condenser (2) is a vertical shell and tube condenser.
41. A NMP solvent recovery system according to claim 19, characterized in that the condenser (2) is a vertical shell and tube condenser.
42. A NMP solvent recovery system according to claim 26, characterized in that the condenser (2) is a vertical shell and tube condenser.
43. A NMP solvent recovery system according to claim 28, characterized in that the condenser (2) is a vertical shell and tube condenser.