A device and method for separating and purifying dimethylformamide

Abstract

The present invention provides a device and method for separating and purifying dimethylformamide, belonging to the technical field of separating and purifying dimethylformamide. The device includes a tank body, a control system, a heat exchange area, a light component separation area, a heavy component separation area, a tail gas recovery area, and a product recovery area. In this method, the prepared mixed solution is separated from the light component impurities in the mixed solution through the light component separation area in the device, and the heavy component impurities in the mixed solution are separated through the heavy component separation area in the device, realizing the separation of light components and heavy components separately and also enabling the continuous separation of light components and heavy components. The separation of light components and heavy components is controlled in a partitioned manner, and both light components and heavy components can achieve cyclic evaporation and condensation during the separation process, improving the purification effect. The light component separation area and the heavy component separation area are set in an integrated structure from top to bottom, with high space utilization rate, reducing the number of devices used and the production input cost.

Description

Technical Field

[0001] The present invention belongs to the technical field of dimethylformamide separation and purification, and particularly relates to a dimethylformamide separation and purification device and method. Background Art

[0002] Dimethylformamide, also known as N,N-dimethylformamide, abbreviated as DMF, is an important organic chemical raw material and an excellent aprotic polar organic solvent. It has stable chemical properties, relatively high boiling point and flash point, and low toxicity. It can be miscible with water, ether, ethanol, kerosene, chlorinated hydrocarbons, aromatic hydrocarbons and most organic solvents. At room temperature, it can dissolve polymers such as ethyl cellulose, nitrocellulose, butyl acetate cellulose, polyacrylonitrile, vinyl chloride, polyvinyl chloride, etc., and is known as an all-purpose solvent, and is widely used in the fields of leather, synthetic fibers, medicine, petrochemicals, electronics, dyes, coatings, metal processing, etc.

[0003] With the continuous development of the application fields of dimethylformamide, a variety of process technologies for synthesizing dimethylformamide from different raw materials have emerged one after another. Among them, the relatively mature and widely used process route is the one-step synthesis method of carbon monoxide: CO + NH(CH3)2 → HCON(CH3)2. This method has simple process, good product quality, and the raw material carbon monoxide can utilize the refined off-gas from the ammonia synthesis plant, with wide raw material sources and low product cost.

[0004] When synthesizing dimethylformamide by the above method, since the raw materials used contain impurities such as ethanol, propanol, polyols, ethers, aldehydes and ketones, and alkanes, etc., the prepared dimethylformamide contains some by-products, such as dimethylacetamide. The unreacted dimethylamine in the reaction process will also be mixed in the dimethylformamide product. The presence of the above impurities will affect the product quality of dimethylformamide.

[0005] To remove the above impurities in dimethylformamide, the commonly used method is rectification and purification, and rectification towers such as a light component removal tower and a heavy component removal tower are used to separately separate the light components and heavy component impurities in dimethylformamide.

[0006] Chinese Utility Model Patent CN217418567U discloses a dimethylformamide separation and purification system, including: a first distillation column, a dimethylformamide reaction product pipeline is connected to the side wall of the first distillation column, and the bottom of the first distillation column communicates with the side wall of the second distillation column to further purify the dimethylformamide and heavy component mixture drawn from the bottom of the column to obtain dimethylformamide. The bottom of the second distillation column is connected to the third distillation column through a pipeline to further purify the heavy component impurities and a small amount of dimethylformamide at the bottom of the second distillation column to obtain dimethylformamide. In this patent, four distillation columns, two adsorbers, and two tail gas absorption towers are used to separate and purify the impurities in dimethylformamide. The method of separating and recovering dimethylformamide by repeatedly distilling multiple distillation columns many times has high equipment investment cost and maintenance cost and large floor area.

[0007] Chinese Utility Model Patent CN203474695U discloses a DMF purification device, including a crude DMF evaporator. The upper part of the crude DMF evaporator is connected to a distillation separation column through a pipeline. A Kettle reboiler is provided at the bottom of the distillation separation column. The middle and lower parts of the distillation separation column are connected to a DMF product tank through a pipeline. A tower condenser is provided at the top of the distillation separation column, and the condensed liquid is transported into a condensate tank through a pipeline. Although the solution of this patent can separate the heavy components, light components and non-condensable gas in the crude DMF, the distillation column used adopts a conventional distillation method. The separation of light components and heavy components is carried out in one distillation column, and no partition control is carried out, so it is difficult to ensure the distillation effect. Summary of the Invention

[0008] Aiming at the problems existing in the above-mentioned prior art, the present invention provides a dimethylformamide separation and purification device and method. The technical problems to be solved by the present invention are how to carry out partition control on the separation of light components and heavy components to improve the purification effect; how to reduce the equipment investment cost and maintenance cost.

[0009] To solve the above technical problems, the present invention provides a dimethylformamide separation and purification device, including a tank body, a control system, a first circulation pipeline, a second circulation pipeline, a third circulation pipeline, a heat exchange area, a light component separation area, a heavy component separation area, a tail gas recovery area and a product recovery area;

[0010] The heat exchange area, the light component separation area and the heavy component separation area are located inside the tank body;

[0011] A light component separation zone is provided below the heat exchange zone, a heavy component separation zone is provided below the light component separation zone, a baffle is provided between the heat exchange zone and the light component separation zone, and a honeycomb perforated plate is provided between the light component separation zone and the heavy component separation zone; the upper part of the heat exchange zone is connected to the tail gas recovery zone; the product recovery zone is connected below the tail gas recovery zone; the control system is electrically connected to the valves provided on the first circulation pipeline, the second circulation pipeline, and the third circulation pipeline;

[0012] A first circulation pipeline is connected between the heat exchange zone and the light component separation zone; the liquid outlet of the second circulation pipeline is connected to the upper part of the heavy component separation zone, and the liquid inlet of the second circulation pipeline is connected to the lower part of the heavy component separation zone; the air inlet hole of the third circulation pipeline is connected to the heavy component separation zone, and the exhaust holes of the third circulation pipeline are respectively connected above the honeycomb perforated plate and the upper part of the product recovery zone.

[0013] Further, the heat exchange zone includes heat exchange tubes, and a cold water inlet and a hot water outlet are provided at the connection of the heat exchange tubes and the tank body, and the cold water inlet is provided below the hot water outlet.

[0014] Further, an inclined angle is formed between the baffle and the horizontal plane.

[0015] Further, the range of the inclined angle is 2° to 10°.

[0016] Further, the highest point of the baffle is set away from the first circulation pipeline, and the lowest point of the baffle is set close to the first circulation pipeline.

[0017] Further, an exhaust hole is provided on the baffle near the highest point of the baffle.

[0018] Further, the baffle includes a cold plate, a hot plate, and a heat insulation layer, and the cold plate, the hot plate, and the heat insulation layer are arranged in sequence from top to bottom.

[0019] Further, the material of the heat insulation layer is glass fiber, asbestos, or rock wool.

[0020] Further, the light component separation zone includes heating tubes, the heating tubes are arranged inside the tank body, and an exhaust valve is provided at the top of the heating tubes.

[0021] Further, the heating tubes are U-shaped tubes.

[0022] Further, the heating tubes are formed by connecting multiple U-shaped tubes in series.

[0023] Further, the first circulation pipeline includes a light component recovery pipe, a first return pipe, a second return pipe, and a feed pipe; the light component recovery pipe is connected above the baffle and communicates with the heat exchange zone; a first return pipe is connected below the light component recovery pipe, a feed pipe is connected below the first return pipe, and a second return pipe is connected between the feed pipe and the outlet of the heating tubes.

[0024] Furthermore, a drain pipe is provided at the outlet of the heating pipe.

[0025] Furthermore, a tenth control valve is provided on the drain pipe.

[0026] Furthermore, a fourth control valve is provided on the light component recovery pipe, a second control valve is provided on the first reflux pipe, and a first control valve is provided on the feed pipe.

[0027] Furthermore, the honeycomb orifice plate includes a plurality of drain holes.

[0028] Furthermore, the heavy component separation area includes heating plates arranged staggeredly from top to bottom, and channels for liquid flow are formed between the heating plates.

[0029] Furthermore, the second circulation pipeline includes a fourth reflux pipe, a liquid discharge pipe, a heavy component recovery pipe, a heavy component tank and a pressure pump. The liquid outlet of the fourth reflux pipe is connected to the heavy component separation area, the liquid inlet of the fourth reflux pipe is connected to the heavy component recovery pipe, the liquid discharge pipe is connected to the bottom of the tank body, a heavy component tank is connected below the liquid discharge pipe, a heavy component recovery pipe is connected below the heavy component tank, and a pressure pump is provided on the heavy component recovery pipe.

[0030] Furthermore, a third control valve is provided on the liquid discharge pipe, an eighth control valve is provided on the fourth reflux pipeline, and a ninth control valve is provided on the heavy component recovery pipe.

[0031] Furthermore, the third circulation pipeline includes a gaseous product recovery pipe, and the gas inlet of the gaseous product recovery pipe is connected to the upper part of the heavy component separation area.

[0032] Furthermore, the gaseous recovery pipe includes two branches. A third reflux pipe is provided on one branch, and the third reflux pipe is connected to the upper part of the exhaust hole honeycomb orifice plate. The exhaust hole of the other branch is connected to the upper part of the product recovery area.

[0033] Furthermore, a seventh control valve is provided on the third reflux pipe.

[0034] Furthermore, a sixth control valve is provided on the branch connected to the upper part of the product recovery area.

[0035] Furthermore, the tail gas recovery area includes a tail gas recovery tank. The tail gas recovery tank is connected to the upper part of the heat exchange area through a first tail gas recovery pipe, and the lower part of the first tail gas recovery pipe is connected to the product recovery area through a second tail gas recovery pipe.

[0036] Furthermore, electromagnetic valves are provided on both the first tail gas recovery pipe and the second tail gas recovery pipe.

[0037] Furthermore, the product recovery area includes a condenser and a product tank. The condenser and the product tank are connected through a liquid product recovery pipe, and the upper part of the condenser is connected to the tank body through a third circulation pipeline.

[0038] Further, a fifth control valve is provided on the liquid product recovery pipe, a hot water pipe is connected to the upper part of the condenser, and a cold water pipe is connected to the lower part of the condenser.

[0039] The present invention provides a method for separating and purifying dimethylformamide. Using the above-mentioned dimethylformamide separation and purification device, it includes the following steps:

[0040] Step S1: Input the raw material liquid into the light component separation area through the first circulation pipeline;

[0041] Step S2: The light component separation area heats the raw material liquid. The gas generated by heating the raw material liquid enters the heat exchange area through the baffle for heat exchange. The gas condenses into a liquid, and the liquid re-enters the light component separation area through the first circulation pipeline for heating;

[0042] Step S3: Cycle according to Step S2. When the light component circulation time set by the control system is reached, the control system opens the fourth control valve provided on the first circulation pipeline. At this time, the liquid condensed in the heat exchange area is discharged through the first circulation pipeline, and the separation and recovery of the light components in the raw material liquid are completed;

[0043] Step S4: Heat the honeycomb orifice plate. After reaching the set temperature, the control system opens the tenth control valve provided on the drain pipe below the light component separation area. The liquid in the light component separation area enters the heavy component separation area through the honeycomb orifice plate and is heated. The gas generated after heating returns to the upper part of the honeycomb orifice plate through the third circulation pipeline and then condenses into a liquid, and then enters the heavy component separation area through the honeycomb orifice plate and is heated again;

[0044] Step S5: Cycle according to Step S4. When the dimethylformamide separation cycle time set by the control system is reached, the control system opens the sixth control valve on the third circulation pipeline, and sends the gas generated by heating in the heavy component separation area into the product recovery area to complete the recovery of dimethylformamide.

[0045] Further, in Step S2, the uncondensed gas enters the tail gas recovery area as tail gas.

[0046] Further, after the remaining liquid that has not formed gas after being heated in the heavy component separation area flows out from the bottom of the tank body, it re-enters the inside of the heavy component separation area through the second circulation pipeline and repeats the cycle. When the heavy component circulation time set by the control system is reached, the control system automatically opens the ninth control valve on the second circulation pipeline to discharge the separated heavy components, realizing the separation and recovery of the heavy components in the raw material liquid.

[0047] Further, in Step S5, the gas entering the product recovery area is first condensed into a liquid and then recovered, and the uncondensed gas enters the tail gas recovery area as tail gas.

[0048] A method for separating and purifying dimethylformamide according to the present invention separates light component impurities in the prepared dimethylformamide mixture through the light component separation zone in the device, and separates heavy component impurities in the mixture through the heavy component separation zone in the device. The above light component separation zone and heavy component separation zone are arranged in the upper and lower sections of the same separation device, which can not only separate light and heavy components separately, but also continuously separate light and heavy components. The separation of light and heavy components is controlled in zones, and both light and heavy components can achieve cyclic evaporation and condensation during the separation process, improving the purification effect.

[0049] A dimethylformamide separation and purification device according to the present invention can control the continuity of the separation operations of light and heavy components through a control system, achieve uninterrupted production, and improve production efficiency. At the same time, the light component separation zone and the heavy component separation zone are arranged in an integrated structure from top to bottom, and the space between the functional units of the device is set tightly with high space utilization rate. Avoid using two sets of equipment, namely a light removal tower and a heavy removal tower, reduce the number of equipment used and the floor area of the device, and lower the production input cost. Brief Description of the Drawings

[0050] Figure 1 It is a schematic structural diagram of a dimethylformamide separation and purification device and method according to the present invention.

[0051] Figure 2 It is a schematic structural diagram of a dimethylformamide separation and purification device and method according to the present invention.

[0052] Figure 3 It is a schematic structural diagram of a dimethylformamide separation and purification device and method according to the present invention.

[0053] Figure 4 It is a schematic diagram of a heating plate of a dimethylformamide separation and purification device and method according to the present invention.

[0054] Among them, 11 is the light component separation area; 12 is the heavy component separation area; 13 is the heat exchange area; 14 is the baffle; 15 is the honeycomb perforated plate; 16 is the condenser; 17 is the product tank; 18 is the heavy component tank; 19 is the tail gas recovery tank; 111 is the heating pipe; 112 is the exhaust valve; 113 is the feed pipe; 114 is the first reflux pipe; 115 is the second reflux pipe; 116 is the first control valve; 117 is the second control valve; 121 is the heating plate; 122 is the liquid outlet pipe; 123 is the third control valve; 131 is the heat exchange pipe; 132 is the cold water inlet; 133 is the hot water outlet; 134 is the light component recovery pipe; 135 is the fourth control valve; 141 is the exhaust hole; 151 is the liquid discharge hole; 161 is the gaseous product recovery pipe; 162 is the liquid product recovery pipe; 163 is the fifth control valve; 164 is the sixth control valve; 165 is the cold water pipe; 166 is the hot water pipe; 167 is the third reflux pipe; 168 is the seventh control valve; 181 is the pressure pump; 182 is the fourth reflux pipe; 183 is the eighth control valve; 184 is the ninth control valve; 185 is the heavy component recovery pipe; 191 is the first tail gas recovery pipe; 192 is the second tail gas recovery pipe; 21 is the liquid discharge pipe; 211 is the tenth control valve; 101 is the first circulation pipeline; 102 is the second circulation pipeline; 103 is the third circulation pipeline. Specific embodiments

[0055] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0056] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed present invention, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0057] It should be noted that similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0058] In the present invention, unless otherwise clearly specified and defined, terms such as "installation", "connection", "linkage", "fixation", etc. shall be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral body; it may be a direct connection or an indirect connection through an intermediate medium, and it may be the communication inside two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0059] In order to better understand the purpose, structure and function of the present invention, the following further describes in detail a dimethylformamide separation and purification device and method of the present invention with reference to the accompanying drawings.

[0060] Example 1:

[0061] As Figure 1 shown, the present invention provides a dimethylformamide separation and purification device, including a tank body, a control system, a first circulation pipeline 101, a second circulation pipeline 102, a third circulation pipeline 103, a heat exchange area 13, a light component separation area 11, a heavy component separation area, a tail gas recovery area and a product recovery area;

[0062] The heat exchange area 13, the light component separation area 11 and the heavy component separation area 12 are located inside the tank body;

[0063] The light component separation area 11 is arranged below the heat exchange area 13, the heavy component separation area 12 is arranged below the light component separation area 11, a baffle 14 is arranged between the heat exchange area 13 and the light component separation area 11, and a honeycomb orifice plate 15 is arranged between the light component separation area 11 and the heavy component separation area 12; the upper part of the heat exchange area 13 is connected to the tail gas recovery area; the product recovery area is connected below the tail gas recovery area; the control system is electrically connected to the valves arranged on the first circulation pipeline 101, the second circulation pipeline 102 and the third circulation pipeline 103;

[0064] The heat exchange area 13 is connected to the light component separation area 11 by the first circulation pipeline 101; the liquid outlet of the second circulation pipeline 102 is connected to the upper part of the heavy component separation area 12, and the liquid inlet of the second circulation pipeline 102 is connected to the lower part of the heavy component separation area 12; the air inlet hole of the third circulation pipeline 103 is connected to the heavy component separation area 12, and the exhaust holes of the third circulation pipeline 103 are respectively connected above the honeycomb orifice plate 15 and the upper part of the product recovery area.

[0065] Example 2:

[0066] As Figure 1As shown in the figure, the present invention provides a dimethylformamide separation and purification device, which includes a tank body, a control system, a first circulation pipeline 101, a second circulation pipeline 102, a third circulation pipeline 103, a heat exchange area 13, a light component separation area 11, a heavy component separation area 12, a tail gas recovery area and a product recovery area;

[0067] The heat exchange area 13, the light component separation area 11 and the heavy component separation area 12 are located inside the tank body;

[0068] The light component separation area 11 is arranged below the heat exchange area 13, the heavy component separation area 12 is arranged below the light component separation area 11, a baffle 14 is arranged between the heat exchange area 13 and the light component separation area 11, and a honeycomb orifice plate 15 is arranged between the light component separation area 11 and the heavy component separation area 12; the upper part of the heat exchange area 13 is connected to the tail gas recovery area; the lower part of the tail gas recovery area is connected to the product recovery area; the control system is electrically connected to the valves arranged on the first circulation pipeline 101, the second circulation pipeline 102 and the third circulation pipeline 103;

[0069] The heat exchange area 13 is connected to the light component separation area 11 by the first circulation pipeline 101; the liquid outlet of the second circulation pipeline 102 is connected to the upper part of the heavy component separation area 12, and the liquid inlet of the second circulation pipeline 102 is connected to the lower part of the heavy component separation area 12; the air inlet hole of the third circulation pipeline 103 is connected to the heavy component separation area 12, and the exhaust holes of the third circulation pipeline 103 are respectively connected above the honeycomb orifice plate 15 and the upper part of the product recovery area.

[0070] The difference between this embodiment and the first embodiment is as follows:

[0071] The bottom of the tank body is inclined, and a liquid outlet pipe 122 is arranged at the lowest position for discharging the substances that have not been completely evaporated into gas in the heavy component separation area 12 into the heavy component tank.

[0072] As Figure 2 shown, the heat exchange area 13 includes heat exchange tubes 131. At the connection between the heat exchange tubes 131 and the tank body, a cold water inlet 132 and a hot water outlet 133 are arranged. The cold water inlet 132 is arranged below the hot water outlet 133; low-temperature cooling water enters from the cold water inlet 132, and the heat-exchanged high-temperature water is discharged from above. To ensure a more effective heat exchange effect, the cold water inlet 132 is arranged close to the exhaust hole 141 of the baffle 14. The gaseous substances coming out of the exhaust hole 141 have the highest temperature and contact and cool down with the low-temperature cooling water first.

[0073] The baffle 14 is inclined to one side, and the inclination angle is 2° to 10°, preferably 5°. The larger the inclination angle, the more conducive it is for the steam below the baffle to rise along the lower surface of the baffle, and the condensed liquid above the baffle is more conducive to flowing down along the upper surface of the baffle. However, if the inclination angle is too large, it will cause waste of the space above and below the baffle.

[0074] The highest point of the baffle 14 is far from the first circulation pipeline 101, and the highest point of the baffle 14 is close to the cold water inlet 132 of the heat exchange tube 131;

[0075] An exhaust hole 141 is arranged on the baffle 14 near the highest point of the baffle 14;

[0076] The lowest point of the baffle 14 is arranged close to the liquid discharge port of the first circulation pipeline 101, which is beneficial to all the liquid flowing down along the upper surface of the baffle entering the liquid discharge port;

[0077] The baffle 14 includes a cold plate, a hot plate and a heat insulation layer, which are arranged in sequence from top to bottom. The heat insulation material between the cold plate and the hot plate is glass fiber, asbestos or rock wool, etc., and preferably glass fiber.

[0078] The light component separation area 11 includes a heating tube 111. An exhaust valve 112 is arranged at the top of the heating tube 111. The heating tube 111 is a U-shaped tube, and the tops of the heating tubes 111 are at the same height to ensure that the exhaust valve 112 at the top of the heating tube 111 is not affected by the liquid pressure caused by the different heights of the tops of the heating tubes 111 during exhaust.

[0079] The light component separation area 11 includes a plurality of serially connected heating tubes 111. The purpose of setting a plurality of serially connected heating tubes 111 is to ensure that the light components in the mixed liquid can be fully vaporized into gas state and separated from the mixed liquid during the flow in the U-shaped tube.

[0080] The first circulation pipeline 101 includes a light component recovery pipe 134, a first return pipe 114, a second return pipe 115 and a feed pipe 113. One end of the light component recovery pipe 134 is arranged near the lowest end of the baffle 14 and is communicated with the heat exchange area 13. A first return pipe 114 is connected below the light component recovery pipe 134, a feed pipe 113 is connected below the first return pipe 114, and a second return pipe 115 is connected between the feed pipe 113 and the outlet of the heating tube 111; A drain pipe 21 is also arranged at the outlet of the heating tube 111, and a tenth control valve 211 is arranged on the drain pipe 21;

[0081] The other outlet of the heating tube 111 is communicated with the heavy component separation area 12;

[0082] A fourth control valve 135 is arranged on the light component recovery pipe 134, a second control valve 117 is arranged on the first return pipe 114, and a first control valve 116 is arranged on the feed pipe 113.

[0083] Example 3:

[0084] As Figure 1As shown in the figure, the present invention provides a device for separating and purifying dimethylformamide, which includes a tank body, a control system, a first circulation pipeline 101, a second circulation pipeline 102, a third circulation pipeline 103, a heat exchange area 13, a light component separation area 11, a heavy component separation area 12, a tail gas recovery area and a product recovery area;

[0085] The heat exchange area 13, the light component separation area 11 and the heavy component separation area 12 are located inside the tank body;

[0086] The light component separation area 11 is arranged below the heat exchange area 13, the heavy component separation area 12 is arranged below the light component separation area 11, a baffle 14 is arranged between the heat exchange area 13 and the light component separation area 11, and a honeycomb orifice plate 15 is arranged between the light component separation area 11 and the heavy component separation area 12; the upper part of the heat exchange area 13 is connected to the tail gas recovery area; the product recovery area is connected below the tail gas recovery area; the control system is electrically connected to the valves arranged on the first circulation pipeline 101, the second circulation pipeline 102 and the third circulation pipeline 103;

[0087] The heat exchange area 13 is connected to the light component separation area 11 by the first circulation pipeline 101; the liquid outlet of the second circulation pipeline 102 is connected to the upper part of the heavy component separation area 12, and the liquid inlet of the second circulation pipeline 102 is connected to the lower part of the heavy component separation area 12; the air inlet hole of the third circulation pipeline 103 is connected to the heavy component separation area 12, and the exhaust holes of the third circulation pipeline 103 are respectively connected above the honeycomb orifice plate 15 and the upper part of the product recovery area.

[0088] The difference between this embodiment and the above embodiments is as follows:

[0089] As Figure 3 shown, the honeycomb orifice plate 15 includes a plurality of liquid discharge holes 151.

[0090] The heavy component separation area includes heating plates 121 arranged in a staggered manner from top to bottom. Liquid flow channels are formed between the heating plates 121. When the liquid flowing down from above flows downward along the heating plates, the flow path of the liquid is in an "S" shape.

[0091] The second circulation pipeline 102 includes a fourth return pipe 182, a liquid outlet pipe 122, a heavy component recovery pipe 185, a heavy component tank 18, and a pressure pump 181. The liquid outlet of the fourth return pipe 182 is connected to the heavy component separation area 12, and the liquid inlet of the fourth return pipe 182 is connected to the heavy component recovery pipe 185. The liquid outlet pipe 122 is connected to the bottom of the tank body, and a third control valve 123 is provided on the liquid outlet pipe 122. The lower part of the liquid outlet pipe 122 is connected to the heavy component tank 18, and the lower part of the heavy component tank 18 is connected to the heavy component recovery pipe 185. A pressure pump 181 is provided on the heavy component recovery pipe 185. The intersection of the fourth return pipe 182 and the heavy component recovery pipe 185 is located downstream of the pressure pump 181, and an eighth control valve 183 is provided on the fourth return pipeline 182.

[0092] The third circulation pipeline 103 includes a gaseous product recovery pipe 161. The gas inlet of the gaseous product recovery pipe 161 is connected to the upper part of the heavy component separation area 12. The recovery pipe 161 includes two branches. A third return pipe 167 is provided on one branch, and the third return pipe 167 is connected to the upper part of the exhaust hole honeycomb plate 15. The exhaust hole of the other branch is connected to the upper part of the product recovery area; a seventh control valve 168 is provided on the branch connected to the upper part of the exhaust hole honeycomb plate 15, and a sixth control valve 164 is provided on the branch connected to the upper part of the product recovery area;

[0093] The tail gas recovery area includes a tail gas recovery tank 19. The tail gas recovery tank 19 is connected to the upper part of the heat exchange area 13 through a first tail gas recovery pipe 191, and the lower part of the first tail gas recovery pipe 191 is connected to the product recovery area through a second tail gas recovery pipe 192; electromagnetic valves are provided on both the first tail gas recovery pipe 191 and the second tail gas recovery pipe 192;

[0094] The product recovery area includes a condenser 16 and a product tank 17. The condenser 16 and the product tank 17 are connected through a liquid product recovery pipe 162. A fifth control valve 163 is provided on the liquid product recovery pipe 162. A hot water pipe 166 is connected to the upper part of the condenser 16, and a cold water pipe 165 is connected to the lower part of the condenser 16.

[0095] The area of a single heating plate 121 in the heavy component separation area 12 accounts for 3 / 4 to 4 / 5 of the cross-sectional area of the heavy component separation area 12, preferably 4 / 5. The larger the area of the heating plate, the more conducive it is for the liquid flowing down from above to contact the heating plate 121, increasing the contact surface between the liquid and the heating plate 121, which is conducive to the heating plate 121 heating the liquid sufficiently. However, if the heating plate 121 occupies too large a cross-sectional area of the heavy component separation area 12, the gap between the heating plate and the side wall of the heavy component separation area will be smaller, and the steam formed after heating and evaporation by the heating plate below cannot quickly rise to reach the gaseous recovery pipe 161.

[0096] As Figure 4As shown, the cross-section of the heating plate 121 is trapezoidal. Its upper surface slopes downward from the fixed position with the side wall of the recombination separation zone 12, and its lower surface slopes upward from the fixed position with the side wall of the recombination separation zone 12. The inclination of the upper surface is conducive to the flow of liquid downward, and the inclination of the lower surface is conducive to the upward discharge of the formed gaseous substances.

[0097] The inclination angle of the upper surface of the heating plate 121 with respect to the horizontal plane is 1° to 3°, preferably 2°. If the inclination angle is too large, the liquid flows downward too fast, which is not conducive to the heating of the liquid by the heating plate.

[0098] The inclination angle of the lower surface of the heating plate 121 with respect to the horizontal plane is 2° to 10°, preferably 5°. The larger the inclination angle of the lower surface, the more conducive it is to the upward discharge of the generated gaseous substances. However, if the inclination angle is too large, the thickness of the fixed part between the heating plate and the side wall of the separation zone is greater, occupying more space, which is not conducive to effectively using the height of the separation zone to set the number of heating plates.

[0099] The widest distance between two adjacent heating plates 121 above and below is 1 to 3 times the thickness of the fixed part of the heating plate 121 with the tank body, and preferably 2 times.

[0100] The number of heating plates arranged in the heavy component separation zone is 6 to 10, and further preferably 8.

[0101] The pressure pump adopted after the heavy component tank is a centrifugal pump.

[0102] All valve bodies in the present invention adopt solenoid valves.

[0103] The control system is a DCS control system.

[0104] A ninth control valve 184 is arranged on the heavy component recovery pipe 185.

[0105] The working process of a dimethylformamide separation and purification device of the present invention is as follows:

[0106] Heat the heating pipe 111 in the light component separation zone 11 to 100°C and maintain it. Feed the prepared dimethylformamide mixed liquid as the raw material liquid into the heating pipe 111 in the light component separation zone 11 through the feed pipe 113. The raw material liquid is continuously heated by the heating pipe 111 while flowing in the heating pipe 111.

[0107] During the flow of the raw material liquid in the heating pipe 111, the generated gaseous substances are discharged from the exhaust valve 112 arranged at the top of the heating pipe 111.

[0108] Control the tenth control valve 211 arranged at the end of the heating pipe 111 through the control system to prevent the liquid in the heating pipe 111 from flowing into the heavy component separation zone 12.

[0109] At this time, the liquid in the heating pipe 111 enters the feed pipe 113 through the second return pipe 115, and together with the raw material liquid entering the feed pipe 113, it is sent into the heating pipe 111 again for reheating and evaporation.

[0110] The gas discharged from the exhaust valve 112 at the top of the heating pipe 111 rises in the light component separation area 11 to the upper baffle 14 and contacts the lower surface of the baffle 14. Since the lower surface of the baffle 14 is a hot plate and its temperature is the same as that of the heating pipe 111, the gaseous substance reaching the lower surface of the baffle 14 always remains gaseous and will not condense. Due to the baffle 14 being inclined at 5°, the gaseous substance reaching the lower surface of the baffle 14 continues to rise and is discharged from the exhaust hole 141 provided at the highest point of the baffle 14 into the upper heat exchange area 13.

[0111] Heat exchange pipes 131 are provided in the heat exchange area 13. Low-temperature water enters from the cold water inlet 132, and the heated high-temperature water is discharged from the hot water outlet 133. The gaseous substance entering the heat exchange area 13 is gradually condensed into a liquid state after heat exchange through the heat exchange pipes 131 and drips onto the upper surface of the baffle 14 below the heat exchange area 13. The upper surface of the baffle 14 is a cold plate, and the liquid dripping onto it will not evaporate again.

[0112] Insulating material fiberglass is provided between the upper and lower surfaces of the baffle 14, so the temperature of the upper cold plate is not affected by the temperature of the lower hot plate.

[0113] The liquid dripping onto the upper surface of the baffle 14 flows along the inclined surface of the upper surface of the baffle 14 inclined at 5° to the liquid outlet and enters the first return pipe 114. The gas not condensed in the heat exchange area 13 passes through the first tail gas recovery pipe 191.

[0114] The fourth control valve 135 on the light component recovery pipe 134 is controlled by the control system to close. The liquid condensed after heat exchange in the heat exchange area 13 enters the feed pipe 113 through the first return pipe 114 and is sent into the heating pipe 111 again together with the raw material liquid in the feed pipe 113 for heating and evaporation.

[0115] The above cycle sets the cycle time for light component separation through the control system. After reaching the set time, the control system automatically opens the fourth control valve 135 on the light component recovery pipe 134. At this time, the light component liquid condensed in the heat exchange area 13 is discharged through the light component recovery pipe 134 to the light component recovery unit. The separation and recovery of the light components in the raw material liquid are completed.

[0116] So far, a dynamic balance is formed at the upper part of the device. The raw material liquid is continuously fed into the heating tube 111, and the heated liquid flows back into the feed pipe 113 through the second reflux pipe 115 and then enters the heating tube 111. The gaseous substances formed by heating in the heating tube 111 continuously enter the upper heat exchange area 13, and the liquid after heat exchange and condensation enters the low-component recovery pipe 134 for recovery. Part of the condensed liquid enters the feed pipe 113 again through the first reflux pipe 114 and is then sent to the heating tube 111 for heating and evaporation.

[0117] The above process continuously cycles. While continuously feeding the raw material liquid, light-component substances are continuously produced and recovered.

[0118] During the above cycle process, the heating plate 121 in the heavy-component separation area 12 below the device is heated to 160 °C and maintained.

[0119] After the temperature of the heating plate 121 is maintained constant, the tenth control valve 211 is opened through the control system. At this time, the liquid in the heating tube 111 is discharged to the upper surface of the honeycomb orifice plate 15 below the light-component separation area 11 through the drain pipe 21.

[0120] The honeycomb orifice plate 15 is inclined at 5°, and the highest end is located below the drain pipe 21. The liquid discharged to the upper surface of the honeycomb orifice plate 15 flows into the lower heavy-component separation area 12 through the drain holes 151 provided on the honeycomb orifice plate 15 under the action of gravity during the process of flowing towards the lower end of the honeycomb orifice plate 15.

[0121] The multiple drain holes 151 on the above honeycomb orifice plate 15 and its inclined design enable the liquid to form a spray shape when discharged into the heavy-component separation area 12 without the need to increase additional conveying power, relying entirely on the action of liquid gravity, and sprinkle on the heating plate in the heavy-component separation area 12, increasing the contact area between the liquid and the heating plate, which is beneficial to the heating and evaporation of the liquid.

[0122] When the liquid reaches the heating plate 121, the liquid is heated. During the continuous downward flow of the liquid, continuously, the liquid is heated and becomes gaseous substances and rises to the inlet of the gaseous product recovery pipe 161.

[0123] The sixth control valve 164 is closed through the control system, and the gaseous substances entering the gaseous product recovery pipe 161 then enter the third reflux pipe 167 and flow back into the light-component separation area 11 through the third reflux pipe 167.

[0124] Since the temperature in the light component separation zone 11 is lower than the temperatures of the gaseous product recovery pipe 161 and the third reflux pipe 167, the gaseous substances entering the light component separation zone 11 condense into liquids and drip onto the honeycomb perforated plate 15 below. They enter the heavy component separation zone 12 through the liquid discharge holes 151 and are heated and evaporated again by the heating plate 121, forming a cycle of heating and evaporation, condensation, and reheating and evaporation.

[0125] When the above cycle reaches the dimethylformamide separation cycle time set by the control system, the control system automatically opens the sixth control valve 164 on the gaseous product recovery pipe 161. The collected gaseous substance, i.e., dimethylformamide, is sent into the condenser 16. After condensation, the gaseous dimethylformamide becomes liquid and is recovered into the product tank 17 through the liquid product recovery pipe 162. The uncondensed gas is discharged as tail gas into the tail gas recovery tank 19 through the second tail gas recovery pipe 192.

[0126] The liquid in the heavy component separation zone 12 that does not form gaseous substances after being heated by the heating plate 121 flows along the heating plate 121 to the bottom of the heavy component separation zone 12. The control system automatically opens the third control valve 123 on the liquid discharge pipe 122, and the liquid flowing to the bottom of the heavy component separation zone 12 is discharged into the heavy component tank 18.

[0127] The liquid in the heavy component tank 18 is sent above the heating plate 121 at the highest position in the heavy component separation zone 12 through the pressure pump 181 via the fourth reflux pipe 182 and is heated and evaporated again by the heating plate 121. This ensures the full separation of dimethylformamide in the mixed liquid.

[0128] When the above cycle reaches the heavy component cycle time set by the control system, the control system automatically opens the ninth control valve 184, and the separated heavy components are discharged to the heavy component recovery unit through the heavy component recovery pipe. The separation and recovery of the heavy components in the raw material liquid are realized.

[0129] Through the above implementation process, the separation of the light components, heavy components, and dimethylformamide in the raw material liquid is completed.

[0130] Example 4:

[0131] The present invention provides a method for separating and purifying dimethylformamide. Using the above dimethylformamide separation and purification device, it includes the following steps:

[0132] Step S1: Input the raw material liquid into the light component separation zone 11 through the first circulation pipeline 101;

[0133] Step S2: The light component separation zone 11 heats the raw material liquid. The gas generated by the heating of the raw material liquid enters the heat exchange zone 13 through the baffle 14 for heat exchange. The gas condenses into a liquid, and the liquid re-enters the light component separation zone 11 through the first circulation pipeline 101 for heating;

[0134] Step S3: Repeat according to Step S2. When the light component circulation time set by the control system is reached, the control system opens the fourth control valve 135 provided on the first circulation pipeline 101. At this time, the liquid formed by condensation in the heat exchange area 13 is discharged through the first circulation pipeline 101, and the separation and recovery of the light components in the raw material liquid are completed;

[0135] Step S4: Heat the honeycomb orifice plate 15. After reaching the set temperature, the control system opens the tenth control valve 211 provided on the drain pipe below the light component separation area. The liquid in the light component separation area enters the heavy component separation area 12 through the honeycomb orifice plate 15 and is heated. The generated gas returns to the upper part of the honeycomb orifice plate 15 through the third circulation pipeline 103 and then condenses into a liquid, and then enters the heavy component separation area 12 through the honeycomb orifice plate 15 and is heated again;

[0136] Step S5: Repeat according to Step S4. When the dimethylformamide separation circulation time set by the control system is reached, the control system opens the sixth control valve 164 on the third circulation pipeline 103, and sends the gas generated by heating in the heavy component separation area into the product recovery area to complete the recovery of dimethylformamide.

[0137] In the said Step S2, the uncondensed gas enters the tail gas recovery area as tail gas.

[0138] In the said Step S4, the remaining liquid that has not formed gas after being heated in the heavy component separation area 12 flows out from the bottom of the tank body, and then re-enters the inside of the heavy component separation area 12 through the second circulation pipeline 102 for repeated circulation. When the heavy component circulation time set by the control system is reached, the control system automatically opens the ninth control valve 184 on the second circulation pipeline 102 to discharge the separated heavy components, realizing the separation and recovery of the heavy components in the raw material liquid;

[0139] The gas entering the product recovery area in the said Step S5 is first condensed into a liquid and then recovered, and the uncondensed gas enters the tail gas recovery area as tail gas.

[0140] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are all included within the protection scope of the present invention.

Claims

1. A dimethylformamide separation and purification device, characterized in that It includes a tank body, a control system, a first circulation pipeline, a second circulation pipeline, a third circulation pipeline, a heat exchange area, a light component separation area, a heavy component separation area, a tail gas recovery area, and a product recovery area; The heat exchange area, the light component separation area, and the heavy component separation area are located inside the tank body; The light component separation area is arranged below the heat exchange area, the heavy component separation area is arranged below the light component separation area, a baffle is arranged between the heat exchange area and the light component separation area, and a honeycomb orifice plate is arranged between the light component separation area and the heavy component separation area; the upper part of the heat exchange area is connected to the tail gas recovery area; the lower part of the tail gas recovery area is connected to the product recovery area; the control system is electrically connected to the valves arranged on the first circulation pipeline, the second circulation pipeline, and the third circulation pipeline; A first circulation pipeline is connected between the heat exchange area and the light component separation area; the liquid outlet of the second circulation pipeline is connected to the upper part of the heavy component separation area, and the liquid inlet of the second circulation pipeline is connected to the lower part of the heavy component separation area; the air inlet hole of the third circulation pipeline is connected to the heavy component separation area, and the exhaust holes of the third circulation pipeline are respectively connected above the honeycomb orifice plate and to the upper part of the product recovery area; An exhaust hole is arranged on the baffle near the highest point of the baffle; The honeycomb orifice plate includes a plurality of liquid drainage holes; The third circulation pipeline includes a gaseous product recovery pipe, and the air inlet of the gaseous product recovery pipe is connected to the upper part of the heavy component separation area; The gaseous recovery pipe includes two branches. A third return pipe is arranged on one branch, and the third return pipe is connected above the honeycomb orifice plate of the exhaust hole, and the exhaust hole of the other branch is connected to the upper part of the product recovery area.

2. The dimethylformamide separation and purification device according to claim 1, characterized in that, The heat exchange area includes heat exchange tubes. A cold water inlet and a hot water outlet are arranged at the connection of the heat exchange tubes and the tank body, and the cold water inlet is arranged below the hot water outlet.

3. The dimethylformamide separation and purification device according to claim 2, characterized in that, An inclined angle is formed between the baffle and the horizontal plane.

4. The dimethylformamide separation and purification device according to claim 3, wherein, The range of the inclined angle is 2° to 10°.

5. The dimethylformamide separation and purification device according to claim 2, wherein, The highest point of the baffle is arranged far away from the first circulation pipeline, and the lowest point of the baffle is arranged close to the first circulation pipeline.

6. The dimethylformamide separation and purification device according to claim 1, characterized in that, The baffle includes a cold plate, a hot plate, and a heat insulation layer, and the cold plate, the hot plate, and the heat insulation layer are arranged in sequence from top to bottom.

7. The dimethylformamide separation and purification device according to claim 1, wherein The material of the heat insulation layer is glass fiber, asbestos, or rock wool.

8. The dimethylformamide separation and purification device according to claim 1, characterized in that, The light component separation area includes heating tubes, and the heating tubes are arranged inside the tank body. An exhaust valve is arranged at the top of the heating tubes.

9. The dimethylformamide separation and purification device according to claim 8, characterized in that, The heating tubes are U-shaped tubes.

10. The dimethylformamide separation and purification device according to claim 8, characterized in that, The heating tubes are formed by connecting a plurality of U-shaped tubes in series.

11. The dimethylformamide separation and purification device according to claim 8, characterized in that, The first circulation pipeline includes a light component recovery pipe, a first return pipe, a second return pipe, and a feed pipe; the light component recovery pipe is connected above the baffle and communicates with the heat exchange area; a first return pipe is connected below the light component recovery pipe, a feed pipe is connected below the first return pipe, and a second return pipe is connected between the feed pipe and the outlet of the heating tubes.

12. The dimethylformamide separation and purification device according to claim 11, wherein, A drain pipe is also arranged at the outlet of the heating tubes.

13. The dimethylformamide separation and purification device according to claim 12, wherein, A tenth control valve is arranged on the drain pipe.

14. The dimethylformamide separation and purification device according to claim 11, wherein, A fourth control valve is arranged on the light component recovery pipe, a second control valve is arranged on the first return pipe, and a first control valve is arranged on the feed pipe.

15. The dimethylformamide separation and purification device according to claim 1, characterized in that, The heavy component separation area includes heating plates arranged in a staggered manner from top to bottom, and channels for liquid flow are formed between the heating plates.

16. The dimethylformamide separation and purification device according to claim 9, characterized in that, The second circulation pipeline includes a fourth return pipe, a liquid outlet pipe, a heavy component recovery pipe, a heavy component tank, and a pressure pump. The liquid outlet of the fourth return pipe is connected to the heavy component separation area, the liquid inlet of the fourth return pipe is connected to the heavy component recovery pipe, the liquid outlet pipe is connected to the bottom of the tank body, a heavy component tank is connected below the liquid outlet pipe, a heavy component recovery pipe is connected below the heavy component tank, and a pressure pump is provided on the heavy component recovery pipe.

17. The dimethylformamide separation and purification device according to claim 16, characterized in that, A third control valve is provided on the liquid outlet pipe, an eighth control valve is provided on the fourth return pipeline, and a ninth control valve is provided on the heavy component recovery pipe.

18. The dimethylformamide separation and purification device according to claim 17, wherein, A seventh control valve is provided on the third return pipe.

19. The dimethylformamide separation and purification device according to claim 17, characterized in that, A sixth control valve is provided on the branch pipeline connected to the upper part of the product recovery area.

20. The dimethylformamide separation and purification device according to claim 1, wherein The tail gas recovery area includes a tail gas recovery tank. The tail gas recovery tank is connected to the upper part of the heat exchange area through a first tail gas recovery pipe, and the lower part of the first tail gas recovery pipe is connected to the product recovery area through a second tail gas recovery pipe.

21. The dimethylformamide separation and purification device according to claim 20, wherein, Solenoid valves are provided on both the first tail gas recovery pipe and the second tail gas recovery pipe.

22. The dimethylformamide separation and purification device according to claim 1, wherein, The product recovery area includes a condenser and a product tank. The condenser and the product tank are connected through a liquid product recovery pipe, and the upper part of the condenser is connected to the tank body through a third circulation pipeline.

23. The dimethylformamide separation and purification device according to claim 22, wherein, A fifth control valve is provided on the liquid product recovery pipe. A hot water pipe is connected to the upper part of the condenser, and a cold water pipe is connected to the lower part of the condenser.

24. A method for separating and purifying dimethylformamide, characterized in that, Using the dimethylformamide separation and purification device according to any one of claims 1-23, the method includes the following steps: Step S1: Input the raw material liquid into the light component separation area through the first circulation pipeline; Step S2: The light component separation area heats the raw material liquid. The gas generated by the heating of the raw material liquid enters the heat exchange area through the baffle for heat exchange. The gas condenses into a liquid, and the liquid re-enters the light component separation area through the first circulation pipeline for heating; Step S3: Circulate according to Step S2. When the light component circulation time set by the control system is reached, the control system opens the fourth control valve provided on the first circulation pipeline. At this time, the liquid condensed by the heat exchange area is discharged through the first circulation pipeline, and the separation and recovery of the light components in the raw material liquid are completed; Step S4: Heat the honeycomb orifice plate. After reaching the set temperature, the control system opens the tenth control valve provided on the drain pipe below the light component separation area. The liquid in the light component separation area enters the heavy component separation area through the honeycomb orifice plate and is heated. The gas generated after heating returns to the upper part of the honeycomb orifice plate through the third circulation pipeline and condenses into a liquid, and then enters the heavy component separation area through the honeycomb orifice plate and is heated again; Step S5: Circulate according to Step S4. When the dimethylformamide separation circulation time set by the control system is reached, the control system opens the sixth control valve on the third circulation pipeline, and sends the gas generated by heating the heavy component separation area into the product recovery area to complete the recovery of dimethylformamide.

25. The method for separating and purifying dimethylformamide according to claim 24, wherein In the said Step S2, the uncondensed gas enters the tail gas recovery area as tail gas.

26. According to the dimethylformamide separation and purification method described in claim 24, in the said Step S4, after the remaining liquid that has not formed gas after being heated in the heavy component separation area flows out from the bottom of the tank body, it re-enters the heavy component separation through the second circulation pipeline Inside the zone, a repeated cycle is carried out. When the recycle time of the heavy components set by the control system is reached, the control system automatically opens the ninth control valve on the second recycle pipeline to discharge the separated heavy components, thereby realizing the separation and recovery of the heavy components in the raw material liquid.

27. The method for separating and purifying dimethylformamide according to claim 24, wherein in step S5, the gas entering the product recovery zone is first condensed into a liquid and then recovered, and the uncondensed gas enters the tail gas recovery zone as tail gas.

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