NMP (N-Methyl Pyrrolidone) gas cooling recovery device

Abstract

The utility model discloses an NMP (N-Methyl Pyrrolidone) gas cooling and recycling device which comprises a recycling tower and a liquid-liquid heat exchange device, a spraying device, an adsorption device and a containing cavity are arranged in the recovery tower from top to bottom. The recovery tower is provided with a gas inlet, a liquid inlet, a liquid outlet and a gas outlet, the gas inlet is communicated with a plurality of gas outlet pipes, and the gas outlet pipes are connected to the containing cavity. The adsorption device is of a net structure and is divided into four layers. A liquid outlet is formed in the bottom of the containing cavity, the tower top liquid inlet is connected with a plurality of spraying devices, a liquid guide plate is arranged below the spraying devices, and liquid flows into the adsorption device through the liquid guide plate. The liquid-liquid heat exchange device comprises a heat exchange pipeline and a heat exchange box, the two ends of the heat exchange pipeline are connected with a liquid inlet and a liquid outlet, and the two ends of the heat exchange box are a water inlet and a water outlet. Liquid in the heat exchange pipeline flows into the liquid inlet after being cooled by the heat exchange box, and circulation is achieved. According to the main device, the cooled liquid can be fully mixed with the liquid at the bottom of the tower body, so that the liquid at the bottom of the tower body is rapidly cooled, the absorption efficiency of the liquid to NMP gas is improved, and the NMP gas is prevented from re-volatilizing.

Description

Technical Field

[0001] The utility model relates to the technical field of gas recovery, and more specifically to an NMP gas cooling and recovery device. Background Art

[0002] NMP is a nitrogen heterocyclic compound and a very important auxiliary material for the production of lithium-ion battery electrodes. It is the most commonly used solvent in the front-end batching process of lithium-ion batteries. It is commonly known as methyl, and its scientific name is N-methylpyrrolidone, with a molecular formula of C5H9NO.

[0003] NMP is the main component of waste gas discharged in the production of lithium-ion batteries and is a toxic gas. If the NMP gas is not recycled, it will not only cause environmental pollution, but also cause a waste of NMP resources. In the prior art, water is often used to spray and absorb the NMP gas. The absorbed solution is lifted by a water suction pump and then sprayed from the top again to continuously absorb the NMP gas. However, the temperature of the dissolved NMP gas increases, and when it is sprayed, the NMP gas components in the solution are easily volatilized again, resulting in low absorption efficiency of the NMP gas. In order to solve the above problems, a heat exchange device is often used to cool the solution of the circulating spray to maintain the absorption rate of the solution to the NMP gas. However, the existing heat exchange device has a poor cooling effect on the solution of the circulating spray, which is not conducive to improving the absorption effect of the NMP gas. Utility Model Content

[0004] The technical problem to be solved by the utility model is to provide an NMP gas cooling and recovery device to effectively recover NMP gas and reduce environmental pollution.

[0005] The utility model solves the technical problem by adopting a technical solution that provides an NMP gas cooling and recovery device, comprising a recovery tower and a liquid-liquid heat exchange device.

[0006] The recovery tower is provided with a receiving chamber, an adsorption device and a spraying device from bottom to top. Water is contained in the receiving chamber. The adsorption device is composed of a wire mesh structure with different placement angles to form a number of small flow holes. In addition, four layers of adsorption devices are placed in the tower body.

[0007] An air inlet pipe, a liquid inlet and a liquid outlet are provided on the side wall of the recovery tower, and an air outlet is provided on the top of the recovery tower. The air inlet pipe is connected to the receiving chamber, allowing NMP gas to enter from the air outlet pipe at the bottom of the air inlet pipe and be adsorbed by the solvent in the receiving chamber.

[0008] The liquid outlet is located at the bottom of the receiving chamber, and the liquid inlet is located at a height higher than the adsorption device and is connected to the spray device;

[0009] The adsorption device is provided with small flow holes for water and gas to pass through. The small flow holes are densely distributed and can adsorb water, and allow the adsorbed water to absorb the rising gas to be recovered.

[0010] The liquid-liquid heat exchange device includes a heat exchange pipe and a heat exchange box, the two ends of the heat exchange pipe are connected to the liquid inlet and the liquid outlet respectively, the upper end of the heat exchange box is provided with a water inlet, and the lower end is provided with a water outlet. The liquid in the heat exchange pipe is cooled by the heat exchange box and flows into the liquid inlet to the spray device, and sprays to the adsorption device, and the adsorption device absorbs the NMP gas that rises and flows into the flow holes.

[0011] Preferably, a cooling pump for transporting the solution in the receiving chamber to the heat exchange pipe is provided on the passage between the liquid outlet and the heat exchange pipe.

[0012] Preferably, a liquid guide plate is further provided on the upper portion of the adsorption device, and conical water-permeable holes are distributed on the liquid guide plate.

[0013] Preferably, the adsorption device is configured as four adsorption disks equally spaced in the upper, middle and lower parts, each of the adsorption disks is formed by cross-stacked multiple single-layer mesh disks at circumferentially equal angles to form a wire mesh adsorption disk, and a number of flow holes are formed, and the four adsorption disks are installed staggered from top to bottom at circumferentially equal angles.

[0014] Preferably, the adsorption device is made of stainless steel.

[0015] Preferably, a plurality of conical small holes are distributed on the liquid guide plate, and the aperture of the upper plane of the liquid guide plate is larger than the aperture of the lower plane, so as to slow down the flow and supply water.

[0016] Preferably, a gas outlet for gas discharge is provided at the top of the recovery tower.

[0017] Preferably, the liquid cold source in the heat exchange box is cooling water, and the cooling water enters the heat exchange box from the water inlet and flows out from the water outlet, and flows in the opposite direction to the recovery liquid in the recovery tower, that is, the flow direction of the liquid in the heat exchange pipe is opposite to the flow direction of the liquid in the heat exchange box.

[0018] Preferably, the air inlet pipe goes deep into the recovery tower, and a plurality of air outlet pipes are arranged at the bottom of the air inlet pipe, and a plurality of air outlet holes are opened at the bottom of the air outlet pipe, and the diameter of the holes is controlled within a size of less than 600 μm. For example, in this preferred embodiment, the diameter of the plurality of air outlet holes is set to a size of more than 400 μm and less than 500 μm, so that the capillary pressure generated when the liquid contacts the pore wall of each pore is sufficient to affect the pressure of the gas, and at the same time, the bubbles formed in the receiving chamber by the exhaust gas discharged from the air outlet pipe can be made smaller, so as to ensure the stability of the gas pressure and increase the contact area between the gas and the liquid in the receiving chamber.

[0019] Preferably, there are a number of small flow holes in the adsorption disks with equal spacing at the top, middle and bottom. To avoid excessive pressure drop when the gas passes through the gas phase channel, causing local flooding, the area of ​​the gas channel should be controlled to be 50%-70% of the tower cross-sectional area. For example, in this preferred example, the ratio is controlled at 50%, and the maximum aperture of the small flow holes is set at 1.3 mm in consideration of the tower diameter, liquid feed amount and spray density.

[0020] Beneficial effects of the utility model:

[0021] The NMP gas cooling and recovery device cools the solution adsorbed with NMP gas through a liquid-liquid heat exchange device, and then sprays it onto the adsorption device, so that the unadsorbed NMP gas is absorbed by the water in the NMP solution, thereby improving the recovery rate of NMP gas, fully contacting the gas and liquid, and achieving a high recovery rate and a high concentration of the recovered waste liquid, which also reduces the demand for water during the circulation process. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a structural schematic diagram of the NMP cooling and recovery device in the embodiment of the utility model;

[0023] Figure 2 yes Figure 1 Schematic diagram of the top view of the adsorption structure in the adsorption device.

[0024] Figure 3 yes Figure 1 Schematic diagram of the outlet pipe at the bottom of the middle air intake duct when viewed from above.

[0025] Markings in the figure: 1-recovery tower, 2-spraying device, 3-liquid guide plate, 4-adsorption device, 5-air inlet pipe, 6-control valve, 7-air outlet pipe, 8-heat exchange pipe, 9-cooling pump, 10-water inlet, 11-water outlet, 12-liquid inlet, 13-liquid outlet, 14-liquid-liquid heat exchange device, 15-heat exchange box, 16-adsorption plate, 17-air outlet, 18-air outlet hole, A-looking up direction, B-receiving chamber, C-circulation hole. DETAILED DESCRIPTION

[0026] In order to have a clearer understanding of the technical features, purposes and effects of the utility model, the specific implementation methods of the utility model are now described in detail with reference to the accompanying drawings. The utility model is further described below in conjunction with the accompanying drawings.

[0027] like Figure 1 As shown, a NMP gas cooling and recovery device in a preferred embodiment of the utility model includes a recovery tower 1 and a liquid-liquid heat exchange device 14. The recovery tower 1 is provided with a receiving chamber B, an adsorption device 4, and a spray device 2 from bottom to top.

[0028] Water is stored in the receiving chamber B. The adsorption device 4 is composed of wire mesh adsorption plates with different placement angles and a number of small flow holes are formed. In addition, four layers of adsorption devices 4 are placed at different positions at the top, middle and bottom of the tower body.

[0029] An air inlet pipe 5, a liquid inlet 12, and a liquid outlet 13 are provided on the side wall of the recovery tower 1. An air outlet 17 is provided on the top of the recovery tower. The air inlet pipe 5 is connected to the receiving chamber B through the air outlet pipe 7 at the bottom. When the control valve 6 is opened, the NMP gas enters the receiving chamber B from the air outlet pipe 7 at the bottom of the air inlet pipe 5 and is adsorbed by the water in the receiving chamber B. The liquid outlet 13 is located at the bottom of the receiving chamber B, and the height of the liquid inlet 12 is higher than the adsorption device 4 and is connected to the spray device 2.

[0030] The liquid-liquid heat exchange device 14 includes a heat exchange pipe 8 and a heat exchange box 15. The two ends of the heat exchange pipe 8 are respectively connected to the liquid inlet and the liquid outlet of the recovery tower. The upper end of the heat exchange box 15 is a water inlet 10, and the lower end is a water outlet 11. The liquid in the heat exchange pipe 8 is cooled by the heat exchange box 15 and flows into the liquid inlet 12 to the spray device 2, sprays to the adsorption device 4, and absorbs the NMP gas rising and flowing into the flow hole C in the adsorption device 4.

[0031] The NMP gas cooling and recovery device cools the solution adsorbed with NMP gas through the liquid-liquid heat exchange device 14, and then sprays it onto the adsorption device 4 through the spray device 2, so that the unadsorbed NMP gas is absorbed by the water in the NMP solution, thereby improving the recovery rate of NMP gas, fully contacting the gas and liquid, and having a high recovery rate and a high concentration of the recovered waste liquid, which also reduces the demand for water in the circulation process.

[0032] The top of the recovery tower 1 is provided with a gas outlet 17 for gas discharge, so that the clean gas after adsorbing and recovering the organic NMP gas is discharged. The pipeline between the liquid outlet 13 and the heat exchange pipeline 8 is provided with a cooling pump 9 for conveying the solution in the receiving chamber B to the heat exchange pipeline 8, and the solution in the receiving chamber B is conveyed to the liquid-liquid heat exchange device 14 for cooling. Furthermore, the liquid cold source in the heat exchange box 15 is cooling water.

[0033] In order to control the speed of water supply to the adsorption device 4, a liquid guide plate 3 for storing water and slowing down the flow is further provided in the recovery tower 1 below the spraying device 2. Conical water permeable holes are distributed on the liquid guide plate 3. When the spraying speed is too fast, water can be stored first and then slowed down to supply water to the adsorption device 4, so as to avoid too fast a speed of water supply downward.

[0034] The adsorption device is made of stainless steel, which not only ensures the strength of the structure, but also has good thermal conductivity. The adsorption device 4 includes four layers of wire mesh adsorption structures 16, namely, upper, middle and lower layers. Each adsorption disk in the adsorption device 4 is formed by stacking a plurality of single-layer mesh disks in sequence at equal intervals in the circumferential direction to form a wire mesh adsorption disk 16. The wire mesh adsorption disk 16 can adsorb the falling solution water and allow the adsorbed water to absorb the rising gas to be recovered.

[0035] At least four adsorption devices 4 are arranged in the absorption tower 1 from top to bottom, and the adsorption devices 4 are staggered from top to bottom at equal circumferential angles so that the flow holes C of each layer are staggered.

[0036] The NMP gas cooling and recovery device uses a high-temperature pure solution to cool and recover organic matter in the waste gas. The cooled solvent is evenly distributed to the adsorption device 4 through the liquid guide plate. When the high-temperature waste gas passes through the adsorption device 4, it is in direct and sufficient contact with the solvent. Most of the organic matter in the waste gas can be absorbed by the solvent and flow back to the receiving chamber B at the bottom of the tower. The heat in the waste gas can be fully transferred to the solvent, and the heat of the solvent is taken away by the low-temperature cooling water through the liquid-liquid heat exchange device 14.

[0037] A plurality of small holes 18 are formed at the bottom of the air outlet pipe 7, so that the capillary pressure generated by the capillary phenomenon when the liquid contacts the hole wall of each small hole 18 is directed toward the inside of the small hole 18, and then the pressure of the gas to pass through each small hole 18 is counterbalanced and a reaction force is generated on the gas, so that the bubbles generated from the small holes 18 can fully merge with the water in the receiving chamber B. The capillary phenomenon formula is as follows:

[0038] h=2γcosθ / ρgr

[0039] Where γ is the surface tension between the liquid and the exhaust gas (unit J / m 2 ), θ is the contact angle, ρ is the liquid density (in kg / m 3 ), g is the acceleration due to gravity (unit: m / s 2 ), r is the radius of the air outlet hole (unit: m).

[0040] From the formula, it can be known that the capillary pressure is inversely proportional to the diameter of each air outlet hole 18. The diameter of the multiple air outlet holes 18 is preferably set to be equal to or less than 600μm. For example, in this preferred embodiment, the diameters of the multiple air outlet holes 18 are set to be greater than 400μm and less than 500μm.

[0041] There are a number of small flow holes C in the adsorption device 4 with equal spacing at the top, middle and bottom. In order to avoid excessive pressure drop when the gas passes through the gas phase channel, causing local flooding, the area of ​​the gas channel should be controlled to be 50%-70% of the cross-sectional area of ​​the recovery tower. The calculation formula is as follows:

[0042] σ=NS1 / S2

[0043] Where σ is the gas channel density, N is the number of flow holes on a single adsorption disk, and S1 is the area of ​​the flow hole (unit: m 2 ), S2 is the cross-sectional area of ​​the absorption tower (unit: m 2 ).

[0044] At the same time, taking into account the tower diameter, liquid feed rate and spray density, the maximum aperture R1 of the flow holes is set at 1.3 mm, and the gas channel density is controlled at 50%.

[0045] It can be understood that the above-mentioned technical features can be used in any combination without limitation.

[0046] The series of detailed descriptions listed above are only specific descriptions of feasible implementation methods of the utility model. They are not intended to limit the protection scope of the utility model. All equivalent methods or changes that do not deviate from the technology of the utility model should be included in the protection scope of the utility model.

Claims

1. A NMP gas cooling and recovery device, characterized in that, It comprises a recovery tower (1) and a liquid-liquid heat exchange device (14); the recovery tower (1) is provided with a receiving chamber (B), an adsorption device (4), and a spray device (2) from bottom to top; The receiving chamber (B) contains NMP gas solvent; The adsorption device (4) comprises four adsorption plates (16) which are evenly spaced at the top, the middle and the bottom. A plurality of small flow holes (C) are distributed on the adsorption plates (16). The small flow holes (C) can allow water and gas to pass through. The recovery tower (1) is provided with an air inlet pipe (5), a liquid inlet (12), and a liquid outlet (13); a top of the recovery tower is provided with an air outlet (17); the air inlet pipe (5) is connected to the receiving chamber (B), so that NMP gas enters the recovery tower (1) from the air inlet pipe (5) and is adsorbed by the solvent in the receiving chamber (B); The liquid outlet (13) is located at the bottom of the receiving chamber (B), and the liquid inlet (12) is located at a height higher than the adsorption device (4) and is connected to the spray device (2) to allow the solvent to flow into the spray device (2); The spray device (2) can spray the solvent into the adsorption device (4), and adsorb the NMP gas in the adsorption device (4); The solvent in the recovery tower (1) flows into the liquid-liquid heat exchange device (14) through the liquid outlet (13), is cooled by the liquid-liquid heat exchange device (14), and then flows into the recovery tower (1) through the liquid inlet (12), thereby realizing a circulating flow; The recovered gas is discharged through the gas outlet (17).

2. A NMP gas cooling and recovery device according to claim 1, characterized in that, The adsorption device (4) comprises four adsorption disks (16) which are evenly spaced at upper, middle and lower positions. Each of the adsorption disks (16) is a wire mesh adsorption disk formed by cross-overlapping a plurality of single-layer mesh disks at equal circumferential angles, and a plurality of small flow holes (C) are formed. The small flow holes (C) between the upper and lower adsorption disks are staggered.

3. A NMP gas cooling and recovery device according to claim 1, characterized in that, A plurality of air outlet pipes (7) are provided at the bottom of the air inlet pipe (5), and air outlet holes (18) are provided at the air outlet pipe openings, so that the gas flows into the receiving chamber (B) through the air outlet holes (18) of the air outlet pipes (7).

4. A NMP gas cooling and recovery device according to claim 1, characterized in that, The small flow holes (C) in the adsorption device (4) are densely distributed and can adsorb water, and allow the adsorbed water to absorb the gas to be recovered that flows through the small flow holes (C).

5. A NMP gas cooling and recovery device according to claim 1, characterized in that, The liquid-liquid heat exchange device (14) comprises a heat exchange pipe (8) and a heat exchange box (15); the two ends of the heat exchange pipe (8) are respectively connected to a liquid inlet (12) and a liquid outlet (13); the upper end of the heat exchange box (15) is provided with a water inlet (10) and the lower end is provided with a water outlet (11); the liquid in the heat exchange pipe (8) is cooled by the heat exchange box (15) and then flows into the liquid inlet (12), and then flows into the recovery tower (1).

6. A NMP gas cooling and recovery device according to claim 5, characterized in that, The flow direction of the liquid in the heat exchange pipe (8) is opposite to the flow direction of the liquid in the heat exchange box (15).

7. A NMP gas cooling and recovery device according to claim 1, characterized in that, A liquid guide plate (3) is also provided on the upper part of the adsorption device, and the liquid guide plate (3) is capable of storing water and slowing down the flow.

8. A NMP gas cooling and recovery device according to claim 7, characterized in that, The liquid guide plate (3) is provided with a plurality of conical small holes, and the hole diameter of the upper plane of the liquid guide plate (3) is larger than the hole diameter of the lower plane.

9. A NMP gas cooling and recovery device according to claim 1, characterized in that, The adsorption device (4) is made of stainless steel.

10. A NMP gas cooling and recovery device according to claim 1, characterized in that: A cooling pump (9) is also provided on the passage between the liquid outlet (13) and the heat exchange pipe (8).

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