Wastewater circulating device in NMP (N-Methyl Pyrrolidone) waste liquid recovery and rectification purification process

Abstract

The utility model discloses a waste water circulating device in NMP waste liquid recovery and rectification purification process, which comprises a tail gas spray tower, a circulating pump, a temporary storage tank, a light component removal rectification tower and a reflux pump, the top of the light component removal rectification tower is provided with a steam outlet, and the steam outlet is connected with a condensed NMP-containing waste water inlet of the reflux pump through a condensation pipeline; a condensed NMP-containing wastewater outlet of the reflux pump is connected with the light component removal rectifying tower through a reflux pipeline and is connected with an NMP-containing wastewater inlet of the temporary storage tank through a connecting pipeline; a spraying liquid outlet pipeline of the tail gas spraying tower is connected with an inlet of the circulating pump; an outlet pipeline of the circulating pump is connected with a spraying liquid inlet of the tail gas spraying tower; and an NMP-containing wastewater outlet of the temporary storage tank is connected with an inlet of the circulating pump through a circulating pipeline. According to the utility model, the NMP-containing wastewater generated by the rectification purification unit can be used for the recovery unit, so that the construction of a wastewater treatment device and a pure water preparation device is reduced, and the equipment investment is saved.

Description

Technical Field

[0001] The utility model belongs to the technical field of wastewater treatment, and in particular relates to a wastewater circulation device in the process of NMP waste liquid recovery and distillation purification. Background Art

[0002] In the process of NMP waste liquid recovery and distillation purification, water acts as a carrier to absorb NMP and does not participate in related reactions in the process of NMP waste liquid recovery and distillation purification. If the NMP waste liquid recovery unit and the distillation purification unit are operated separately, the recovery unit needs to be injected with pure water, and the distillation purification unit will produce NMP-containing wastewater that needs to be disposed of, so it is necessary to build more wastewater treatment devices and pure water preparation devices.

[0003] Based on the water use index requirements of the NMP waste liquid recovery unit and the analysis of the impurity content in the NMP-containing waste water produced by the NMP waste liquid distillation and purification unit, the NMP-containing waste water produced by the distillation and purification unit can be used in the recovery unit, that is, recycled in the NMP waste liquid recovery unit and the distillation and purification unit. However, there is currently no technology for combining them for recycling. Utility Model Content

[0004] Technical problem solved: In response to the above technical problems, the utility model provides a wastewater circulation device in the process of NMP waste liquid recovery and distillation purification, which can use the NMP-containing wastewater generated by the distillation purification unit for the recovery unit, reducing the construction of wastewater treatment equipment and pure water preparation equipment, and saving equipment investment.

[0005] Technical solution: A wastewater circulation device in the process of NMP waste liquid recovery and distillation purification, comprising a tail gas spray tower, a circulation pump, a temporary storage tank, a light removal distillation tower and a reflux pump, wherein a steam outlet is provided at the top of the light removal distillation tower, and the steam outlet is connected to the condensed NMP-containing wastewater inlet of the reflux pump through a condensation pipeline; the condensed NMP-containing wastewater outlet of the reflux pump is connected to the light removal distillation tower through a reflux pipeline, and is connected to the NMP-containing wastewater inlet of the temporary storage tank through a connecting pipeline; the spray liquid outlet pipeline of the tail gas spray tower is connected to the inlet of the circulation pump, and the outlet pipeline of the circulation pump is connected to the spray liquid inlet of the tail gas spray tower; the NMP-containing wastewater outlet of the temporary storage tank is connected to the inlet of the circulation pump through a circulation pipeline.

[0006] Preferably, a solenoid valve is provided on the circulation pipeline.

[0007] Preferably, the device also includes a condensing and freezing surface cooler and a waste heat recovery heat exchanger, the air outlet of the condensing and freezing surface cooler is connected to the air inlet of the exhaust gas spray tower and the fresh air inlet of the waste heat recovery heat exchanger by pipelines, and the air inlet pipeline of the condensing and freezing surface cooler is connected to the exhaust outlet of the waste heat recovery heat exchanger.

[0008] Furthermore, the condensing and freezing surface cooler is provided with a condensing component and a freezing component, wherein the condensing component uses cooling water as a cooling medium, and the freezing component uses chilled water as a cooling medium.

[0009] Furthermore, the device also includes an NMP waste liquid tank, the waste liquid inlet of the NMP waste liquid tank is connected to the discharge port of the condensing and freezing surface cooler through a waste liquid collecting pipe, and the waste liquid outlet pipeline of the NMP waste liquid tank is connected to the NMP distillation inlet of the light removal distillation tower after passing through a filter.

[0010] Furthermore, the device also includes a coater, the air inlet pipeline of the coater is connected to the fresh air outlet of the waste heat recovery heat exchanger, and the NMP waste gas outlet pipeline of the coater is connected to the exhaust inlet of the waste heat recovery heat exchanger.

[0011] Preferably, the device further comprises a dehydration distillation tower and a deheaving distillation tower, the NMP distillation outlet pipeline of the delight distillation tower is connected to the NMP distillation inlet of the dehydration distillation tower, and the NMP distillation outlet pipeline of the dehydration distillation tower is connected to the NMP distillation inlet of the deheaving distillation tower.

[0012] Beneficial effects: The utility model can not only reduce the construction of separate wastewater treatment devices and pure water preparation devices, but also use water as a carrier for NMP recovery without chemical reaction in the entire system, without the introduction of external impurities, and the NMP impurities carried during purification have no effect on the recovery system, that is, the wastewater generated by distillation and the water quality requirements required for tail gas treatment in the recovery system are fully matched. By setting up temporary storage tanks and related pipelines, the water quality requirements of each level of spray absorption can be met. Compared with the prior art, the utility model has the following beneficial effects:

[0013] 1. Reduce the construction of NMP-containing wastewater treatment equipment during NMP distillation and purification, reduce the construction of pure water preparation equipment during NMP waste liquid recovery, and save equipment investment.

[0014] 2. The caching function based on the temporary storage tank can effectively solve the problem of mismatch between the operating status of the recovery unit and the distillation and purification unit.

[0015] 3. The utility model has the remarkable characteristics of simple operation, low cost, small footprint, and environmental friendliness, and has good engineering application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the structure of the utility model;

[0017] The meanings of the numbers in the figure are as follows: 1. tail gas spray tower, 2. circulation pump, 3. temporary storage tank, 4. light removal distillation tower, 5. reflux pump, 6. solenoid valve, 7. condensing and freezing surface cooler, 8. waste heat recovery heat exchanger, 9. NMP waste liquid tank, 10. coating machine, 11. dehydration distillation tower, 12. heavy removal distillation tower. DETAILED DESCRIPTION

[0018] The utility model is further described below in conjunction with the accompanying drawings and specific embodiments. Example 1

[0019] like Figure 1 As shown, a wastewater circulation device in the process of NMP waste liquid recovery and distillation purification includes a tail gas spray tower 1, a circulation pump 2, a temporary storage tank 3, a light removal distillation tower 4 and a reflux pump 5. The top of the light removal distillation tower 4 is provided with a steam outlet, and the steam outlet is connected to the condensed NMP-containing wastewater liquid inlet of the reflux pump 5 through a condensation pipeline; the condensed NMP-containing wastewater liquid outlet of the reflux pump 5 is connected to the light removal distillation tower 4 through a reflux pipeline, and is connected to the NMP-containing wastewater liquid inlet of the temporary storage tank 3 through a connecting pipeline; the spray liquid outlet pipeline of the tail gas spray tower 1 is connected to the inlet of the circulation pump 2, and the outlet pipeline of the circulation pump 2 is connected to the spray liquid inlet of the tail gas spray tower 1; the NMP-containing wastewater liquid outlet of the temporary storage tank 3 is connected to the inlet of the circulation pump 2 through a circulation pipeline. The device also includes a dehydration distillation tower 11 and a deheaving distillation tower 12. The NMP distillation outlet pipeline of the delight distillation tower 4 is connected to the NMP distillation inlet of the dehydration distillation tower 11, and the NMP distillation outlet pipeline of the dehydration distillation tower 11 is connected to the NMP distillation inlet of the deheaving distillation tower 12. A solenoid valve 6 is provided on the circulation pipeline.

[0020] The light removal distillation tower 4, the dehydration distillation tower 11, and the heavy removal distillation tower 12 constitute a NMP waste liquid distillation and purification unit. The NMP waste liquid is sequentially processed by the light removal distillation tower 4, the dehydration distillation tower 11, and the heavy removal distillation tower 12 to achieve liquid phase material separation and purification. During the distillation process of the light removal distillation tower 4, water and a small amount of NMP will be distilled into steam and discharged from the top of the tower, and then condensed into NMP-containing waste water. After this part of the NMP-containing waste water passes through the condensation NMP-containing waste water liquid outlet of the reflux pump 5, a part of it is refluxed to the light removal distillation tower 4, and the other part is directly introduced into the temporary storage tank 3 to be supplied to the tail gas spray tower 1 for use.

[0021] The device also includes a condensing and freezing cooler 7, a waste heat recovery heat exchanger 8 and a coating machine 10. The air outlet of the condensing and freezing cooler 7 is connected to the air inlet of the tail gas spray tower 1 and the fresh air inlet of the waste heat recovery heat exchanger 8 through pipelines, and the air inlet pipeline of the condensing and freezing cooler 7 is connected to the exhaust outlet of the waste heat recovery heat exchanger 8. The condensing and freezing cooler 7 is provided with a condensing component and a freezing component, wherein the condensing component uses cooling water as a cooling medium, and the freezing component uses freezing water as a cooling medium. The device also includes an NMP waste liquid tank 9, the waste liquid inlet of the NMP waste liquid tank 9 is connected to the discharge port of the condensing and freezing cooler 7 through a waste liquid collection pipe, and the waste liquid outlet of the NMP waste liquid tank 9 is connected to the NMP distillation inlet of the light removal distillation tower 4 through a pipeline after a filter. The air inlet pipeline of the coating machine 10 is connected to the fresh air outlet of the waste heat recovery heat exchanger 8, and the NMP waste gas outlet pipeline of the coating machine 10 is connected to the exhaust inlet of the waste heat recovery heat exchanger 8.

Claims

1. A wastewater circulation device for NMP waste liquid recovery and distillation purification process, characterized in that: The invention comprises a tail gas spray tower (1), a circulation pump (2), a temporary storage tank (3), a light removal distillation tower (4) and a reflux pump (5). The top of the light removal distillation tower (4) is provided with a steam outlet, and the steam outlet is connected to the condensed NMP-containing wastewater inlet of the reflux pump (5) through a condensation pipeline; the condensed NMP-containing wastewater outlet of the reflux pump (5) is connected to the light removal distillation tower (4) through a reflux pipeline, and is connected to the NMP-containing wastewater inlet of the temporary storage tank (3) through a connecting pipeline; the spray liquid outlet pipeline of the tail gas spray tower (1) is connected to the inlet of the circulation pump (2), and the outlet pipeline of the circulation pump (2) is connected to the spray liquid inlet of the tail gas spray tower (1); the NMP-containing wastewater outlet of the temporary storage tank (3) is connected to the inlet of the circulation pump (2) through a circulation pipeline.

2. A wastewater circulation device in a NMP waste liquid recovery and distillation purification process according to claim 1, characterized in that, A solenoid valve (6) is provided on the circulation pipeline.

3. A wastewater circulation device in a NMP waste liquid recovery and distillation purification process according to claim 1, characterized in that, The device further comprises a condensing and freezing surface cooler (7) and a waste heat recovery heat exchanger (8); the air outlet of the condensing and freezing surface cooler (7) is respectively connected to the air inlet of the exhaust gas spray tower (1) and the fresh air inlet of the waste heat recovery heat exchanger (8) through pipelines; and the air inlet pipeline of the condensing and freezing surface cooler (7) is connected to the exhaust outlet of the waste heat recovery heat exchanger (8).

4. A wastewater circulation device in a NMP waste liquid recovery and distillation purification process according to claim 3, characterized in that, The condensing and freezing surface cooler (7) is provided with a condensing component and a freezing component, wherein the condensing component uses cooling water as a cooling medium, and the freezing component uses freezing water as a cooling medium.

5. A wastewater circulation device in a NMP waste liquid recovery and distillation purification process according to claim 3, characterized in that, The device further comprises an NMP waste liquid tank (9), the waste liquid inlet of the NMP waste liquid tank (9) being connected to the discharge port of the condensing and freezing surface cooler (7) via a waste liquid collecting pipe, and the waste liquid outlet of the NMP waste liquid tank (9) being connected to the NMP distillation inlet of the light removal distillation tower (4) via a pipeline after passing through a filter.

6. A wastewater circulation device in a NMP waste liquid recovery and distillation purification process according to claim 3, characterized in that, The device further comprises a coating machine (10), wherein an air inlet pipeline of the coating machine (10) is connected to a fresh air outlet of the waste heat recovery heat exchanger (8), and an NMP waste gas outlet pipeline of the coating machine (10) is connected to an exhaust air inlet of the waste heat recovery heat exchanger (8).

7. A wastewater circulation device in a NMP waste liquid recovery and distillation purification process according to claim 1, characterized in that, The device further comprises a dehydration distillation tower (11) and a deheaving distillation tower (12); the NMP distillation outlet pipeline of the delight distillation tower (4) is connected to the NMP distillation inlet of the dehydration distillation tower (11); and the NMP distillation outlet pipeline of the dehydration distillation tower (11) is connected to the NMP distillation inlet of the deheaving distillation tower (12).

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