CN218784668U - Evaporation filtering device for processing dimethyl formamide synthetic mixed feed liquid - Google Patents

Abstract

The utility model provides an evaporation and filtration device for processing dimethyl formamide synthetic mixed feed liquid, which is sequentially provided with an evaporation area, a filtration area and a recovery area from top to bottom, and adjacent areas are separated by a baffle; the evaporation area is provided with a high-temperature steam inlet and a condensate water outlet, the outer top of the evaporation area is provided with a cleaning unit, and the cleaning unit is connected with the evaporation pipe and can controllably clean the inside of the evaporation pipe; the filtering area is provided with a filtering unit and a feeding pipe, and the feeding pipe is respectively connected with a supply device for synthesizing mixed feed liquid by dimethyl formamide and the filtering unit; the evaporation pipe penetrates through the baffle plate and the filtering unit from the top of the evaporation area downwards, and the lower port of the evaporation pipe is positioned in the recovery area; the upper part of the evaporation tube is provided with a gas phase outlet, the lower port of the evaporation tube is provided with a valve, and the side wall of the lower part of the evaporation tube is provided with a filtrate inlet communicated with the filtrate output of the filtration unit. The utility model discloses with evaporation and filtration process integration in one set of device, realize filtering and evaporation and go on in succession, area is little.

Description

Evaporation filtering device for processing dimethyl formamide synthetic mixed feed liquid

Technical Field

The utility model relates to a synthetic technical field of dimethyl formamide, more specifically relates to handle evaporation and filtration device of synthetic mixed feed liquid of dimethyl formamide.

Background

Dimethylformamide, also known as N, N-dimethylformamide, abbreviated as DMF in English, is a widely used chemical raw material, and is generally industrially prepared by high-temperature high-pressure reaction of dimethylamine and carbon monoxide in the presence of a catalyst. In the reaction process, impurities in the raw materials are easy to react with the catalyst at high temperature to produce byproducts such as sodium formate, sodium carbonate and the like. The reacted substances need to be filtered and evaporated to remove the by-products and the catalyst after the reaction, and then are sent to a subsequent lightness-removing tower for deep separation. In the evaporation separation process, crystals are easily formed and attached to the inner wall of the device, so that the evaporation effect is influenced, and the device needs to be periodically stopped for cleaning and maintenance after a period of production, so that the production efficiency is reduced, and the production cost is increased.

In order to solve the problems, patent CN207203493U discloses a dimethyl formamide evaporation application device, which comprises an evaporation separator, an evaporation circulating pump, a filter and an evaporation heater. The bottom material outlet of the evaporation separator is connected with the input end of an evaporation circulating pump, the output end of the evaporation circulating pump is respectively connected with the input end of a filter and the input end of an evaporation heater, and the output end of the filter and the output end of the evaporation heater are respectively connected with the middle part of the evaporation separator. According to the technical scheme, a part of materials enter a filter to remove impurities such as a catalyst after being pressurized by an evaporation circulating pump, clear liquid returns to an evaporation separator, the materials in the evaporation separator are repeatedly circulated, and circulating liquid returns to the filter to gradually remove a small amount of impurities such as the catalyst which are not filtered; the other part of the material enters an evaporation heater through an evaporation circulating pump, and returns to an evaporation separator after being heated by steam, so that the components are separated from a liquid phase to a gas phase under certain temperature control.

According to the technical scheme, two sets of filtering and evaporating systems are adopted and connected in a parallel connection mode, so that one set of system is produced, and the other set of system is cleaned and maintained. Although the problem that maintenance can be carried out without stopping the machine is solved, the equipment cost which is twice of the production capacity is required, and when one set of system is maintained, a conventional cleaning maintenance method is still adopted, the automatic cleaning function is not realized, and the maintenance cost is not reduced. In addition, the filtration unit and the evaporation unit are separately arranged and connected through a pipeline in the patent scheme, so that the occupied area of the equipment is large. In addition, because of the increase of the length of the pipeline, crystals are easily formed on the inner wall of the pipeline, which is not beneficial to the maintenance of equipment.

In view of this, the utility model discloses the application is specially proposed.

SUMMERY OF THE UTILITY MODEL

In view of the problem that exists among the prior art in the product evaporation process behind the synthetic N, N-dimethylformamide, the utility model provides a under the condition that does not influence the production productivity, realize the equipment self-cleaning under the not stop state and maintain, reduction in production's input cost.

In order to solve the technical problem, the utility model provides an evaporation filtering device for processing a mixed feed liquid synthesized by dimethyl formamide, which is provided with an evaporation area, a filtering area and a recovery area from top to bottom in sequence, wherein a first baffle is arranged between the evaporation area and the filtering area, and a second baffle is arranged between the filtering area and the recovery area;

the evaporation zone is provided with a high-temperature steam inlet and a condensate outlet, the outer top of the evaporation zone is provided with a cleaning unit, and the cleaning unit is connected with the evaporation tube and can controllably clean the inside of the evaporation tube; the filtering area is provided with a filtering unit and a feeding pipe, one end of the feeding pipe is connected with a supply device for synthesizing mixed feed liquid by dimethylformamide through a pressure pump, and the other end of the feeding pipe is connected with the filtering unit;

the evaporation tube penetrates through the first baffle, the filtering unit and the second baffle from the top of the evaporation zone downwards, and the lower port of the evaporation tube is positioned in the recovery zone;

the upper part of the evaporation tube is provided with a gas phase outlet, the lower port of the evaporation tube is provided with a valve which can be controlled to open and close, and the side wall of the lower part of the evaporation tube is provided with a filtrate inlet which is communicated with the filtrate output of the filtering unit.

As one example, the filtering unit includes a casing and a filter element, a space between the casing and the filter element is a liquid inlet area, and the inside of the filter element is filtrate; the evaporation tube passes through the center of the filtrate zone.

As a case, a plurality of groups of the filtering units, the evaporating pipes and the cleaning units are arranged, and the feeding pipes are connected with each filtering unit through a plurality of feeding branch pipes respectively provided with valves.

As a case, the filtering unit further comprises a scraping unit, one end of the scraping unit is connected to the shell, the other end of the scraping unit provided with a scraping structure is arranged on the periphery of the filter element, and the scraping unit is used for scraping filter substances on the outer surface of the filter element.

As a case, strike off the unit and constitute by connecting block, connecting rod and second doctor-bar, the one end of connecting rod is connected on the casing, the other end is connected with the connecting block, the connecting block centers on the periphery of locating the filter core, the bottom surface that the connecting block was located to the second doctor-bar be close to the one side of filter core and with the surface contact of filter core.

As a case, set up vertical guide rail on the inner wall of casing, the connecting rod reciprocates along vertical guide rail, drives the second doctor-bar on the connecting block and reciprocates along the filter core.

As a case may be, the bottom of the connection block is provided with a third wiper blade in a direction perpendicular to the filter cartridge, said third wiper blade being at an angle of 45 ° to the vertical.

As a case, an annular guide rail is arranged on the inner wall of the shell, the connecting rod moves along the annular guide rail to drive a third scraping blade arranged at the lower part of the connecting block to move, and the filtering foreign matters which are scraped by the second scraping blade and fall on the bottom plate of the liquid inlet area are scraped to the filtering matter discharge port along the bottom plate of the liquid inlet area and are discharged into the recovery area.

As a case, the cleaning unit comprises a motor, a telescopic rod and a cleaning mechanism, wherein one end of the telescopic rod is connected with the motor, and the other end of the telescopic rod is connected with the cleaning mechanism which can be extended into and out of the evaporation tube.

As one example, the cleaning mechanism includes a first wiper and a water nozzle, the telescopic rod is a hollow structure, one end of the telescopic rod is connected to an external cleaning liquid storage device, and the other end of the telescopic rod is connected to the water nozzle.

Compared with the prior art, the utility model have following advantage:

1. the utility model discloses concentrate evaporation process and filtration process in one set of device, realize filtering and evaporation and go on in succession. When the device needs to be cleaned, the single filtering and evaporating unit can be independently cleaned and maintained automatically without stopping operation, and the production efficiency is improved.

2. The utility model discloses not only realize serialization production, reduced the area of device moreover, reduced the production input cost.

3. The utility model discloses a device is suitable for and designs evaporation filter unit's cover number according to the demand of production productivity in a flexible way, when wasing the maintenance to single evaporation filter unit, and remaining evaporation filter unit still can satisfy the requirement of productivity.

4. Further, the utility model discloses an evaporation filter unit's washing is maintained and can be gone on automatically through control procedure, need not artificial intervention, and abluent control procedure is independent with production control procedure, washs each evaporation filter unit in turn when can realizing producing, has greatly realized high-efficient production.

Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by the practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims thereof as well as the appended drawings.

Drawings

The accompanying drawings are included to provide a further understanding of the embodiments of the present invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the embodiments of the invention and not to limit the embodiments of the invention.

FIG. 1 is a sectional view showing the structure of an evaporation and filtration apparatus for processing a mixed feed liquid for synthesizing dimethylformamide according to the present invention.

Fig. 2 is a schematic view of the structure of the filter unit of fig. 1.

Fig. 3 is a top view of the filter unit of fig. 2.

Fig. 4 is a schematic structural view of the cleaning unit.

FIG. 5 is a schematic view showing the state of the cleaning unit in the case of the evaporation filtration.

Fig. 6 is a schematic view of the state of the cleaning unit at the time of cleaning.

Fig. 7 is a schematic view of the structure of the cleaning mechanism.

Fig. 8 is a schematic view showing a state of the scraping unit after scraping when the filter cartridge is cleaned.

Fig. 9 is a schematic structural view of the scraping unit.

Fig. 10 is a schematic view illustrating the movement of the scraping unit.

Fig. 11 is an exemplary diagram of an automatic control mode of the evaporation filtration apparatus of the present invention.

Description of the reference numerals:

11. a filtration and evaporation device; 12. an evaporation zone; 13. a filtration zone; 14. a recovery zone; 15. an evaporation tube; 16. a filtration unit; 17. a cleaning unit; 121. a high temperature steam inlet; 122. a condensed water outlet; 123. a first baffle plate; 131. a feeding pipe; 132. a second baffle; 133. a feed branch pipe; 134. a pressure pump; 170. a gas phase collecting pipe; 151. a butterfly valve; 152. a filtrate inlet; 153. a crystallized product outlet; 161. a filter element; 162. a liquid inlet zone; 163. a filtrate zone; 18. a scraping unit; 19. a first control valve; 151. a butterfly valve; 152. a filtrate inlet; 153. a crystallized product outlet; 181. connecting blocks; 182. a connecting rod; 171. a motor; 172. a telescopic rod; 173. a cleaning mechanism; 41. a gas phase outlet; 71. a first blade; 72. a water jet; 81. a second control valve; 82. a filtrate discharge port; 91. a second wiper blade; 92. a third wiper blade; 101. a vertical guide rail; 102. and a ring-shaped guide rail.

Detailed Description

In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the drawings of the embodiments of the present invention will be combined below to clearly and completely describe the technical solution of the embodiments of the present invention. It is to be understood that the embodiments described are some, not all embodiments of the invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive work based on the described embodiments of the present invention, belong to the protection scope of the present invention.

As shown in fig. 1, the filtration and evaporation apparatus 11 is sequentially provided with an evaporation zone 12, a filtration zone 13, and a recovery zone 14 from top to bottom, wherein a first baffle 123 is provided between the evaporation zone 12 and the filtration zone 13, and a second baffle 132 is provided between the filtration zone 13 and the recovery zone 14.

The filtering and evaporating device 11 is provided with an evaporating pipe 15, a filtering unit 16 and a cleaning unit 17, wherein the filtering unit 16 is positioned in the filtering area 13, preferably in the middle of the filtering and evaporating device 11. The evaporation tube 15 extends from the top of the evaporation zone 12 downward through the first baffle 123, the second baffle 132 to the recovery zone 14. The evaporation pipe 15 passes through the center of the filter unit 16, and a butterfly valve 151 is arranged at the joint of the evaporation pipe 15 and the bottom of the filter unit 16 and used for controlling the material in the evaporation pipe 15 to be discharged into the lower recovery area 14 through the opening of the butterfly valve 151. The evaporating tube 15 is provided with a filtrate inlet 152 on a side wall near the bottom of the filter unit 16 for allowing the filtrate filtered by the filter element 161 to enter the evaporating tube 15.

The upper part of the evaporation tube 15 is also provided with a gas phase outlet 41, the gas phase outlet 41 is connected with a gas phase collecting tube 170, and the gas phase collecting tube 170 is connected with a lightness-removing tower in the rear end process.

The filtering section 13 is provided with a feed pipe 131, one end of the feed pipe 131 is connected to a supply device of a dimethylformamide synthetic mixed feed liquid through a pressure pump 134, and the other end is connected to the filtering unit 16. The cleaning unit 17 is provided at the outer top of the evaporation zone 12 and communicates with the top end of the evaporation tube 15.

As a specific example, as shown in fig. 2, the filter unit 16 includes a housing, a filter element 161, and a scraping unit 18, wherein a space between the housing and the filter element 161 is an inlet region 162, and a filtrate region 163 is inside the filter element 161.

As a specific example, the filtrate outlet 82 is provided at a position close to the filter element 161 on the bottom plate of the liquid inlet region 162, and preferably 2 to 4 filtrate outlets are provided along the circumferential direction of the filter element 161.

Preferably, referring to fig. 8, the filtrate discharge port 82 is provided with a second control valve 81 for controlling the opening or closing of the discharge port 82.

One end of the scraping unit 18 is connected to the housing, and the other end of the scraping unit having a scraping structure is disposed at the periphery of the filter element 161, so as to scrape off and clean the filtered material on the outer surface of the filter element 161 when the filter unit 16 is maintained and cleaned.

As a specific example, as shown in fig. 3 and 9, the scraping unit 18 is composed of a connection block 181, a connection bar 182, and a second scraping blade 91, and one end of the connection bar 182 is connected to the housing and the other end is connected to the connection block 181. The connecting block 181 is circular, surrounds the periphery of the filter element 161 for a circle, the second scraping blade 91 is arranged on the circumference of the bottom surface of the connecting block 181 close to one side of the filter element 161, the second scraping blade 91 inclines towards the filter element 161 and can be contacted with the filter element 161, and the second scraping blade 91 is favorable for scraping off the filtered matter on the outer surface of the filter element 161.

The second scraping blades 91 are uniformly arranged along the inner circumference of the connecting block 181 and contact with the outer surface of the filter element 161, so that solid foreign matters remained on the surface of the filter element 161 can be scraped.

As a mode, a vertical guide rail 101 is arranged on the inner wall of the shell, the connecting rod 182 moves up and down along the vertical guide rail 101, the circular second scraping blade 91 on the connecting block 181 is driven to move up and down along the filter element 161, and solid foreign matters on the outer surface of the filter element 161 are scraped.

As a way, the bottom of the connection block 181 is provided with a third wiper 92 in a direction perpendicular to the filter cartridge 161, the third wiper 92 forming an angle of 45 ° with the vertical direction. Preferably, a plurality of groups of third scraping blades 92 are arranged at intervals along the bottom circumference of the connecting block 181.

When the connecting rod 182 moves to the lower portion of the liquid inlet region 162 along the vertical rail 101, the second scraper 91 finishes scraping off the foreign matters on the surface of the filter element 161.

Furthermore, an annular guide rail 102 is arranged on the inner wall of the housing, the connecting rod 182 moves along the annular guide rail 102 to drive the third scraping blade 92 arranged at the lower part of the connecting block 181 to move, and the filtered foreign matters which are scraped by the second scraping blade 91 and fall on the bottom plate of the liquid inlet area 162 are scraped to the filtered matter discharge port 82 along the bottom plate of the liquid inlet area 162 and are discharged into the recovery area 14.

As a mode, the filtering and evaporating device 11 is cylindrical as a whole, and includes a plurality of filtering units 16 and evaporating pipes 15, each filtering unit 16 corresponds to one evaporating pipe 15, the filtering units 16 and the evaporating pipes 15 form a set according to the aforementioned mode, the feeding pipe 131 is connected with each filtering unit 16 through an independent feeding branch pipe 133, and the feeding branch pipes 133 are respectively provided with a first control valve 19 for controlling the feeding of the feed liquid into the filtering units 16. Referring to fig. 1 to 2, the mixed liquid after the synthesis of n, n-dimethylformamide is fed from the feed pipe 131 of the middle filtering section 13 and then controllably fed into each filtering unit 16 through the feed branch pipes 133 respectively provided with the first control valves 19.

The feeding branch pipe 133 of the feeding pipe 131 is connected with the liquid inlet area 162, the mixed liquid synthesized by N, N-dimethylformamide passes through the filter element 161 from the liquid inlet area 162 inwards, the mixed liquid is filtered by the filter element 161 and reaches the filtrate area 163, and the liquid entering the filtrate area 163 enters the evaporation pipe 15 through the filtrate inlet 152 arranged on the lower side wall of the evaporation pipe 15.

The specific process of introducing the mixed feed liquid for dimethylformamide synthesis to be treated into the evaporation tube 15 will be described below with reference to FIGS. 1 to 3:

after being pressurized by a pressure pump 134, the mixed feed liquid for synthesizing the dimethyl formamide is input into a feed branch pipe 133 through a feed pipe 131, a control system opens a first control valve 19, the mixed feed liquid enters a liquid inlet area 162, then the mixed feed liquid enters a filter element 161 for filtration, the filtrate is attached to the outer surface of the filter element 161, and the filtrate enters a filtrate area 163 through the filter element 161. The liquid entering the filtrate zone 163 enters the evaporator tubes 15 through the filtrate inlet 152 provided in the sidewall of the evaporator tubes 15 near the bottom of the filtrate zone 163 and gradually rises up the evaporator tubes 15 under the continuous pressurization of the pressure pump 134.

Referring to fig. 1, 2 and 4, after the filtrate filtered by the filter element 161 enters the evaporation tube 15 through the filtrate inlet 152, the filtrate in the evaporation tube 15 continuously rises to reach the evaporation tube section in the evaporation zone 12 under the action of the pressure pump 134 for supplying the mixed feed liquid of dimethylformamide synthesis.

The middle part of the evaporation zone 12 is provided with a high-temperature steam inlet 121, and the bottom of the evaporation zone 12 is provided with a condensed water outlet 122. High-temperature steam is introduced into the evaporation zone 12 through the high-temperature steam inlet 121, the evaporation zone 12 is filled with the high-temperature steam to heat and evaporate the low-temperature filtrate in the evaporation tubes 15, the high-temperature steam is cooled by the low-temperature liquid in the evaporation tubes 15 to become condensed water, and then the condensed water is discharged through the condensed water outlet 122.

After the low-temperature filtrate in the evaporation tube 15 is heated by high-temperature steam, a part of formed gas is discharged from the gas phase outlet 41 at the upper part to the gas phase collecting tube 170, and the gas phase collecting tube 170 sends the collected gaseous substances to a light component removal tower of a subsequent process for separation.

A part of the liquid which firstly enters the evaporation tube 15 and rises to the evaporation zone 12 is evaporated into a gas state and discharged, and the liquid which does not form the gas state continues to be mixed with the liquid which then enters the evaporation tube 15 in the evaporation tube 15 and is continuously heated and evaporated by the high-temperature steam in the evaporation zone 12. After repeated circulation, the liquid in the evaporation tube 15 is continuously formed into a gas phase and discharged to the downstream lightness removing process.

In the above process, the liquid level in the evaporation tube 15 is ensured to be always lower than the height of the gas phase outlet 41 at the upper part of the evaporation tube 15 by the pressure control of the pressure pump 134. After a period of operation, crystals may form on the inner wall of the evaporation tube 15, which may affect the subsequent evaporation process. It is necessary to clean the inner wall of the evaporation tube 15 by the cleaning unit 17 after the apparatus is operated for a certain period of time.

As a specific example, referring to fig. 1, 4-7, the cleaning unit 17 includes a motor 171, a telescopic rod 172, and a cleaning mechanism 173, wherein one end of the telescopic rod 172 is connected to the motor 171, and the other end is connected to the cleaning mechanism 173. The cleaning mechanism 173 includes a first blade 71 and a water jet 72, and the water jet 72 is connected to an external cleaning liquid storage device.

As a specific example, the first scraper 71 has a circular cross section, and the outer circumference of the circular cross section contacts the inner wall of the evaporation tube 15 to scrape off crystals on the inner wall of the evaporation tube 15.

As an example, referring to fig. 7, the water jet 72 is formed in an elliptical shape and is opened on the first blade 71, preferably along the circumferential direction of the first blade 71, and the jet direction is inclined toward the inner wall of the evaporation tube 15.

Referring to fig. 5 and 6, when the inner wall of the evaporation tube 15 needs to be cleaned, the butterfly valve 151 at the bottom of the evaporation tube 15 is opened to discharge the liquid in the evaporation tube 15. The motor 171 runs to extend the telescopic rod 172, and the telescopic rod 172 pushes the cleaning mechanism 173 to move downward along the evaporation tube 15, so as to drive the first scraper 71 to move downward along the inner wall of the evaporation tube 15, and scrape off the crystals on the inner wall.

In one embodiment, the telescopic rod 172 is hollow inside and connected to an external cleaning solution storage device, the telescopic rod 172 is connected to the water spray nozzle 72, and the cleaning solution is supplied to the cleaning mechanism 173 through the inner cavity of the telescopic rod 172 and sprayed to the inner wall of the evaporation tube 15 through the water spray nozzle 72 to further clean the inner wall of the evaporation tube 15.

Because the multiple groups of evaporation tubes 15 and the filtering units 16 are arranged, the groups are mutually independent to control work, and the work of other evaporation tubes 15 and the work of the filtering units 16 are not influenced in the process of cleaning the evaporation tubes 15, so that the evaporation tubes 15 can be cleaned in turn during production.

With the water jet 72 of the cleaning unit 17, the back flushing of the filter element 161 in the filter unit 16 can be further realized, as follows:

the butterfly valve 151 at the lower part of the evaporation tube 15 is closed, the water spraying function of the cleaning unit 17 at the upper part of the evaporation tube 15 is started, and water is sprayed into the evaporation tube 15 through the water spray nozzle 72. The water sprayed into the evaporation tube 15 reversely enters the filtrate area 163 through the filtrate inlet 152 on the lower side wall of the evaporation tube 15, and reversely passes through the filter element 161 under a certain pressure of the liquid inside the evaporation tube 15, further washing away the foreign matters on the outer surface of the filter element 161.

The liquid after the filter element 161 is washed enters the liquid inlet area 162, and at this time, the second control valve 81 on the bottom plate of the liquid inlet area 162 is opened, and the mixed liquid after the filter element 161 is washed is discharged to the recovery area 14 at the lower part of the device.

The utility model discloses an evaporation filter equipment can realize the full automatization, adjusts the operation of each process through control system, as an example, and figure 11 has given a control mode that can accomodate, but it is not as the injecing to the protection domain, and ordinary technical personnel are in the utility model discloses under above-mentioned basic device's the design, can alternate and use other control methods, it also belongs to the utility model discloses a scope.

The control system is divided into two independent control units of production control and cleaning control.

The production control unit is mainly used for controlling the pressure regulation of the feeding and pressure pump 134 and the control of the temperature and the amount of the high-temperature steam injection during the evaporation and filtration. The use or the deactivation of the single group of evaporation tubes 15 and the filtering unit 16 is controlled by controlling the opening and the closing of the first control valve 19. And each first control valve 19 can be controlled individually, enabling independent use of each single set of evaporator tubes 15 and filter units 16.

The cleaning control unit mainly controls the operations of the cleaning unit 17 and the scraping unit 18.

For a single set of evaporator tubes 15 and filter units 16, the control system switches the single set of evaporator tubes 15 and filter units 16 to production control when the corresponding first control valve 19 is open, with its corresponding wash unit 17 being controlled to be closed.

When the first control valve 19 corresponding to a single set of evaporation tube 15 and filter unit 16 is closed, the control system switches the set of evaporation tube 15 and filter unit 16 to cleaning control, and the production control unit of the set of evaporation tube 15 and filter unit 16 is closed. In the switching process of the control unit, the use states of other groups of evaporation tubes 15 and filter units 16 are not affected.

Although the present invention has been described in connection with the above embodiments, the above description is only for the purpose of understanding the present invention, and is not intended to limit the present invention. The present invention is not limited to the above embodiments, but may be modified in various forms and details without departing from the spirit and scope of the present invention.

Claims (10)

1. The evaporation filtering device for processing the dimethyl formamide synthetic mixed liquid is characterized in that the evaporation filtering device (11) is sequentially provided with an evaporation area (12), a filtering area (13) and a recovery area (14) from top to bottom, a first baffle (123) is arranged between the evaporation area (12) and the filtering area (13), and a second baffle (132) is arranged between the filtering area (13) and the recovery area (14);

the evaporation area (12) is provided with a high-temperature steam inlet (121) and a condensed water outlet (122), the outer top of the evaporation area is provided with a cleaning unit (17), and the cleaning unit (17) is connected with the evaporation pipe (15) and can be used for controllably cleaning the inside of the evaporation pipe (15); the filtering area (13) is provided with a filtering unit (16) and a feeding pipe (131), one end of the feeding pipe (131) is connected with a supply device of the dimethyl formamide synthetic mixed liquid through a pressure pump (134), and the other end of the feeding pipe is connected with the filtering unit (16);

the evaporation pipe (15) penetrates through the first baffle plate (123), the filtering unit (16) and the second baffle plate (132) from the top of the evaporation area (12) downwards, and the lower port of the evaporation pipe is positioned in the recovery area (14);

the upper part of the evaporation tube (15) is provided with a gas phase outlet (41), the lower port is provided with a valve which can be controlled to open and close, and the side wall of the lower part of the evaporation tube (15) is provided with a filtrate inlet (152) communicated with the filtrate output of the filtering unit (16).

2. The evaporative filtration apparatus for processing a dimethylformamide synthetic mixed feed liquid as claimed in claim 1, wherein said filtration unit (16) comprises a housing and a filter element (161), a space between said housing and said filter element (161) is a feed area (162), and an interior of said filter element (161) is a filtrate area (163); the evaporation tube (15) passes through the center of the filtrate zone (163).

3. The evaporation filtering device for processing the mixed feed liquid for the synthesis of dimethylformamide as claimed in claim 2, characterized in that a plurality of groups of said filtering units (16), evaporating pipes (15) and cleaning units (17) are provided, and the feeding pipe (131) is connected with each filtering unit (16) through a plurality of feeding branch pipes (133) respectively provided with valves.

4. The evaporative filtration device for processing a dimethylformamide synthetic mixed feed liquid as claimed in claim 2, wherein said filtration unit (16) further comprises a scraping unit (18), one end of the scraping unit (18) is connected to the housing, and the other end provided with a scraping structure is disposed on the periphery of the filter element (161) for scraping off the filtered substances on the outer surface of the filter element (161).

5. The evaporation filtering device for processing the mixed feed liquid of the dimethylformamide synthesis as claimed in claim 4, wherein said scraping unit (18) is composed of a connecting block (181), a connecting rod (182) and a second scraping blade (91), one end of the connecting rod (182) is connected to the housing, the other end is connected to the connecting block (181), said connecting block (181) is disposed around the periphery of the filter element (161), and the second scraping blade (91) is disposed on the side of the bottom surface of the connecting block (181) close to the filter element (161) and contacts with the outer surface of the filter element (161).

6. The evaporation filtering device for processing the mixed feed liquid in the synthesis of dimethyl formamide as claimed in claim 5, wherein a vertical guide rail (101) is arranged on the inner wall of the casing, and the connecting rod (182) moves up and down along the vertical guide rail (101) to drive the second scraping blade (91) on the connecting block (181) to move up and down along the filter element (161).

7. The evaporative filtration apparatus for processing a dimethylformamide synthesis mixed liquor as claimed in claim 5, wherein the bottom of the connecting block (181) is provided with a third scraper (92) in a direction perpendicular to the filter element (161), and the third scraper (92) forms an angle of 45 ° with the vertical direction.

8. The evaporation and filtration device for processing the mixed feed liquid of the dimethylformamide synthesis as claimed in claim 7, wherein an annular guide rail (102) is provided on the inner wall of the housing, the connecting rod (182) moves along the annular guide rail (102) to drive the third scraper (92) provided at the lower part of the connecting block (181) to move, and the filtered foreign matters which are scraped off by the second scraper (91) and fall on the bottom plate of the liquid inlet region (162) are scraped to the filtered matter discharge port (82) along the bottom plate of the liquid inlet region (162) and discharged to the recovery region (14).

9. The evaporation filtering device for processing the mixed feed liquid for the synthesis of dimethylformamide as claimed in claim 1, wherein said cleaning unit (17) comprises a motor (171), a telescopic rod (172) and a cleaning mechanism (173), one end of the telescopic rod (172) is connected to the motor (171), and the other end is connected to the cleaning mechanism (173) which can be inserted into and removed from the interior of the evaporation tube (15).

10. The apparatus as claimed in claim 9, wherein the cleaning mechanism (173) comprises a first blade (71) and a water spraying port (72), and the telescopic rod (172) has a hollow structure and has one end connected to an external cleaning solution storage device and the other end connected to the water spraying port (72).

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