Nitration alkali wash tail gas recycling device

Abstract

The utility model provides a nitration alkali wash tail gas recycling device, and belongs to the technical field of nitration. The nitration alkali wash tail gas recycling device comprises an alkali wash kettle, an alkali wash tower and a sodium carbonate feeding tank, an exhaust pipeline of the alkali wash kettle is connected with the alkali wash tower, a sodium hydroxide inlet pipeline and a sodium carbonate extraction pipeline are arranged on the alkali wash tower, and the other end of the sodium carbonate extraction pipeline is connected with the sodium carbonate feeding tank. And the sodium carbonate feeding tank is connected with the alkali washing kettle through a sodium carbonate feeding pipeline. According to the nitration alkali washing tail gas recycling device provided by the utility model, carbon dioxide discharged in the alkali washing process of the alkali washing kettle is discharged into the alkali washing tower, a sodium hydroxide solution is injected into the alkali washing tower, a generated sodium carbonate solution is discharged into the sodium carbonate feeding tank from the alkali washing tower, and the sodium carbonate solution in the sodium carbonate feeding tank is discharged into the alkali washing kettle; and the carbon dioxide is prevented from being directly discharged into the atmosphere, so that the carbon emission is reduced.

Description

Technical Field

[0001] The utility model belongs to the technical field of nitrification, and in particular relates to a nitrification alkali washing tail gas recycling device. Background Art

[0002] TDI (toluene diisocyanate) is an important organic chemical raw material and chemical product, which is widely used in dyes, medicines, chemicals and other fields. The TDI production process includes nitration, hydrogenation, photochemical and other process steps. The nitration reaction step will produce DNT (dinitrotoluene). At present, the m-dinitrotoluene DNT produced by the polyurethane TDI industry usually uses sodium carbonate as an alkaline washing medium. The sodium carbonate solution is used to remove trace acids and phenolic impurities entrained in DNT. Sodium carbonate is a relatively mild alkaline medium as an alkaline washing medium and has high operating safety. However, the sodium carbonate raw material generally exists in the form of solid raw materials. Therefore, the sodium carbonate raw material needs to be dissolved and diluted before use. During the alkaline washing process, carbon dioxide will be generated. The generated carbon dioxide is generally directly discharged into the atmosphere, increasing carbon emissions. Utility Model Content

[0003] The utility model aims to provide a nitrification alkali washing tail gas recycling device, aiming to solve the problem of increasing carbon emissions due to carbon dioxide emissions in the alkali washing process.

[0004] To achieve the above-mentioned purpose, the technical solution adopted by the utility model is: to provide a nitration alkali washing tail gas recycling device, including an alkali washing kettle, an alkali washing tower and a sodium carbonate feeding tank, the exhaust pipeline of the alkali washing kettle is connected to the alkali washing tower, the alkali washing tower is provided with a sodium hydroxide discharge pipeline and a sodium carbonate production pipeline, the other end of the sodium carbonate production pipeline is connected to the sodium carbonate feeding tank, and the sodium carbonate feeding tank is connected to the alkali washing kettle through the sodium carbonate feeding pipeline.

[0005] In a possible implementation, a nitrogen oxide absorption tower is provided between the alkali washing kettle and the alkali washing tower, the exhaust pipeline is connected to the nitrogen oxide absorption tower, and an outlet pipeline of the nitrogen oxide absorption tower is connected to the alkali washing tower.

[0006] In a possible implementation manner, a compressor is provided on the exhaust pipeline.

[0007] In a possible implementation, a water inlet pipeline is disposed at the upper end of the nitrogen oxide absorption tower, and a liquid outlet pipeline is disposed at the lower end.

[0008] In a possible implementation, the sodium hydroxide discharge pipeline is arranged at the upper end of the alkali washing tower, and the gas outlet pipeline is arranged at the lower end of the alkali washing tower.

[0009] In a possible implementation, the sodium hydroxide discharge pipeline is connected to a flow control valve, and the flow control valve is connected to a water supply pipeline and a sodium hydroxide supply pipeline.

[0010] In a possible implementation, a bottom circulation pump is provided on the sodium carbonate production pipeline.

[0011] In a possible implementation, a sodium carbonate reflux pipeline is provided on the sodium carbonate production pipeline, and the other end of the sodium carbonate reflux pipeline is connected to the sodium hydroxide discharge pipeline.

[0012] In a possible implementation, a cooler is provided on the sodium carbonate reflux line.

[0013] In a possible implementation, the sodium carbonate feed tank is connected to a sodium carbonate external supply pipeline, and a feed pump is provided on the sodium carbonate feed pipeline.

[0014] The beneficial effects of the nitrification alkali washing tail gas recycling device provided by the utility model are:

[0015] Compared with the prior art, the invention is provided with an alkali washing kettle, an alkali washing tower and a sodium carbonate feeding trough. An exhaust pipe is connected between the alkali washing kettle and the alkali washing tower. Carbon dioxide discharged from the alkali washing kettle during the alkali washing process is mixed with other gases and discharged into the alkali washing tower through the exhaust pipe to prevent carbon dioxide from being directly discharged into the atmosphere. A sodium hydroxide discharge pipeline is provided on the alkali washing tower. The sodium hydroxide solution is discharged into the alkali washing tower through the sodium hydroxide discharge pipeline. In the alkali washing tower, carbon dioxide in the mixed gas reacts with sodium hydroxide in the sodium hydroxide solution to generate sodium carbonate, and the carbon dioxide in the mixed gas is removed. The solution containing sodium carbonate is discharged through a sodium carbonate extraction pipeline provided on the alkali washing tower and flows into the sodium carbonate feeding trough. The sodium carbonate feeding trough is connected to the alkali washing kettle through a sodium carbonate feeding pipeline. The solution containing sodium carbonate is discharged into the alkali washing kettle through the sodium carbonate feeding pipeline. Sodium carbonate is used as a raw material in the alkali washing process, and repeated recycling is realized, thereby reducing production costs and the amount of labor required for dissolving sodium carbonate. Moreover, there is no calcium impurity in the cyclically generated sodium carbonate-containing solution, thereby reducing the influence of calcium impurities on the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 A schematic diagram of the structure of a nitrification alkali washing tail gas recycling device provided in an embodiment of the utility model.

[0018] In the figure: 1. alkali washing kettle; 2. exhaust pipeline; 3. compressor; 4. water inlet pipeline; 5. nitrogen oxide absorption tower; 6. gas outlet pipeline; 7. liquid outlet pipeline; 8. alkali washing tower; 9. sodium hydroxide discharge pipeline; 10. flow control valve; 11. water supply pipeline; 12. sodium hydroxide supply pipeline; 13. gas discharge pipeline; 14. sodium carbonate production pipeline; 15. tower kettle circulation pump; 16. sodium carbonate reflux pipeline; 17. cooler; 18. control valve; 19. sodium carbonate feed trough; 20. sodium carbonate external supply pipeline; 21. sodium carbonate feed pipeline; 22. feed pump. DETAILED DESCRIPTION

[0019] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0020] Please refer to Figure 1 A specific embodiment of a nitration alkali washing tail gas recycling device provided by the utility model is now described, including an alkali washing kettle 1, an alkali washing tower 8 and a sodium carbonate feeding tank 19, the exhaust pipeline 2 of the alkali washing kettle 1 is connected to the alkali washing tower 8, the alkali washing tower 8 is provided with a sodium hydroxide discharge pipeline 9 and a sodium carbonate production pipeline 14, the other end of the sodium carbonate production pipeline 14 is connected to the sodium carbonate supply tank 19, and the sodium carbonate supply tank 19 is connected to the alkali washing kettle 1 through a sodium carbonate supply pipeline 21.

[0021] The utility model provides a nitration alkali washing tail gas recycling device. Compared with the prior art, the utility model is provided with an alkali washing kettle 1, an alkali washing tower 8 and a sodium carbonate feeding tank 19. An exhaust pipe is connected between the alkali washing kettle 1 and the alkali washing tower 8. The carbon dioxide discharged in the alkali washing process in the alkali washing kettle 1 is mixed with other gases and discharged into the alkali washing tower 8 through the exhaust pipe to avoid the carbon dioxide being directly discharged into the atmosphere. A sodium hydroxide discharge pipeline 9 is provided on the alkali washing tower 8. The sodium hydroxide solution is discharged into the alkali washing tower 8 through the sodium hydroxide discharge pipeline 9. In the alkali washing tower 8, the carbon dioxide in the mixed gas and the sodium hydroxide in the sodium hydroxide solution are reacted. The reaction generates sodium carbonate, and the carbon dioxide in the mixed gas is removed. The solution containing sodium carbonate is discharged through the sodium carbonate extraction pipeline 14 arranged on the alkali washing tower 8, and flows into the sodium carbonate feeding tank 19. The sodium carbonate feeding tank 19 is connected to the alkali washing kettle 1 through the sodium carbonate feeding pipeline 21. The solution containing sodium carbonate is discharged into the alkali washing kettle 1 through the sodium carbonate feeding pipeline 21. Sodium carbonate is used as a raw material in the alkali washing process, and repeated recycling is achieved, which reduces the production cost and the labor required for dissolving sodium carbonate. In addition, there is no calcium impurity in the cyclically generated sodium carbonate-containing solution, which reduces the influence of calcium impurities on the device.

[0022] For details, please refer to Figure 1 , comprising an alkali washing kettle 1, an alkali washing tower 8 and a sodium carbonate feeding tank 19, an exhaust pipeline 2 is arranged between the alkali washing kettle 1 and the alkali washing tower 8, the carbon dioxide generated in the alkali washing process in the alkali washing kettle 1 enters the alkali washing tower 8 through the exhaust pipeline 2, a gas exhaust pipeline 13 is arranged at the upper end of the alkali washing tower 8, a sodium hydroxide discharge pipeline 9 is arranged on the alkali washing tower 8, a sodium hydroxide solution is injected into the alkali washing tower 8, carbon dioxide and sodium hydroxide generate sodium carbonate, and the obtained solution containing sodium carbonate avoids direct discharge of carbon dioxide into the atmosphere, thereby reducing carbon emissions, and a sodium carbonate extraction pipeline 14 is arranged at the lower end of the alkali washing tower 8. At the end, the solution containing sodium carbonate is discharged into the sodium carbonate feeding tank 19 through the sodium carbonate extraction pipeline 14. The sodium carbonate extraction pipeline 14 is provided with a control valve 18. The amount of the extracted sodium carbonate solution is controlled according to the liquid level in the alkali washing tower 8. The sodium carbonate feeding tank 19 is connected to the alkali washing kettle 1 through the sodium carbonate feeding pipeline 21. The solution containing sodium carbonate is returned to the alkali washing kettle 1 through the sodium carbonate feeding pipeline 21, so as to realize repeated recycling, reduce the production cost, reduce the labor required for dissolving sodium carbonate, and there is no calcium impurity in the cyclically produced sodium carbonate solution, which reduces the influence of calcium impurities on the device.

[0023] As a specific implementation of the nitrification alkali washing tail gas recycling device provided by the utility model, please refer to Figure 1 A nitrogen oxide absorption tower 5 is arranged between the alkali washing kettle 1 and the alkali washing tower 8 , the exhaust pipeline 2 is connected to the nitrogen oxide absorption tower 5 , and the outlet pipeline 6 of the nitrogen oxide absorption tower 5 is connected to the alkali washing tower 8 .

[0024] For details, please refer to Figure 1 The nitrogen oxide absorption tower 5 is arranged between the alkali washing kettle 1 and the alkali washing tower 8, the exhaust pipeline 2 connects the alkali washing kettle 1 and the nitrogen oxide absorption tower 5, the first end of the exhaust pipeline 2 is arranged at the upper end of the alkali washing kettle 1, and the second end of the exhaust pipeline 2 is arranged at the lower end of the side wall of the nitrogen oxide absorption tower 5. The nitrogen oxide absorption tower 5 is used to absorb nitrogen oxides in the discharged gas, further treat the gas, and reduce the pollution of the discharged gas to the environment.

[0025] As a specific implementation of the nitrification alkali washing tail gas recycling device provided by the utility model, please refer to Figure 1 A compressor 3 is provided on the exhaust pipeline 2.

[0026] For details, please refer to Figure 1 The compressor 3 is arranged on the exhaust pipeline 2 to facilitate the transportation of the gas.

[0027] As a specific implementation of the nitrification alkali washing tail gas recycling device provided by the utility model, please refer to Figure 1A water inlet pipeline 4 is arranged at the upper end of the nitrogen oxide absorption tower 5, and a liquid outlet pipeline 7 is arranged at the lower end.

[0028] For details, please refer to Figure 1 The upper end of the side wall of the nitrogen oxide absorption tower 5 is provided with a water inlet pipeline 4 for discharging desalted water, and the lower end of the nitrogen oxide absorption tower 5 is provided with a liquid outlet pipeline 7 for discharging liquid.

[0029] As a specific implementation of the nitrification alkali washing tail gas recycling device provided by the utility model, please refer to Figure 1 The sodium hydroxide discharge pipeline 9 is arranged at the upper end of the alkali washing tower 8, and the gas outlet pipeline 6 is arranged at the lower end of the alkali washing tower 8.

[0030] For details, please refer to Figure 1 The sodium hydroxide discharge pipeline 9 is arranged at the upper end of the alkali washing tower 8, and the sodium hydroxide solution is discharged from the upper end of the alkali washing tower 8 and flows downward. The gas outlet pipeline 6 is arranged at the lower end of the alkali washing tower 8, and the gas containing carbon dioxide is discharged from the lower end of the alkali washing tower 8 and flows upward, thereby improving the absorption effect of carbon dioxide.

[0031] As a specific implementation of the nitrification alkali washing tail gas recycling device provided by the utility model, please refer to Figure 1 A flow control valve 10 is connected to the sodium hydroxide discharge pipeline 9, and a water supply pipeline 11 and a sodium hydroxide supply pipeline 12 are connected to the flow control valve 10.

[0032] For details, please refer to Figure 1 The outlet of the flow control valve 10 is arranged on the sodium hydroxide discharge pipeline 9, and the two inlets of the flow control valve 10 are respectively connected to the water supply pipeline 11 and the sodium hydroxide supply pipeline 12. The sodium hydroxide supply pipeline 12 is used to supply a sodium hydroxide solution with a higher concentration, and the water supply pipeline 11 is used to supply desalted water. The flow control valve 10 is controlled to adjust the concentration of the sodium hydroxide solution entering the sodium hydroxide discharge pipeline 9.

[0033] As a specific implementation of the nitrification alkali washing tail gas recycling device provided by the utility model, please refer to Figure 1 A bottom circulation pump 15 is provided on the sodium carbonate production pipeline 14.

[0034] For details, please refer to Figure 1 The tower bottom circulation pump 15 is arranged on the sodium carbonate extraction pipeline 14 and is arranged close to the alkali washing tower 8 to facilitate the discharge of the sodium carbonate solution.

[0035] As a specific implementation of the nitrification alkali washing tail gas recycling device provided by the utility model, please refer to Figure 1A sodium carbonate reflux pipeline 16 is provided on the sodium carbonate production pipeline 14, and the other end of the sodium carbonate reflux pipeline 16 is connected to the sodium hydroxide discharge pipeline 9.

[0036] For details, please refer to Figure 1 The first end of the sodium carbonate reflux pipeline 16 is arranged on the sodium carbonate production pipeline 14, and is arranged between the tower bottom circulation pump 15 and the control valve 18. The second end of the sodium carbonate reflux pipeline 16 is connected to the sodium hydroxide discharge pipeline 9. The solution containing sodium carbonate discharged from the alkali washing tower 8 can be mixed with the sodium hydroxide solution and returned to the alkali washing tower 8 through the sodium carbonate reflux pipeline 16, which is helpful to control the liquid level in the alkali washing tower 8 and increase the stability of the device.

[0037] As a specific implementation of the nitrification alkali washing tail gas recycling device provided by the utility model, please refer to Figure 1 A cooler 17 is provided on the sodium carbonate reflux pipeline 16.

[0038] For details, please refer to Figure 1 A cooler 17 is provided on the sodium carbonate reflux pipeline 16. The sodium hydroxide and carbon dioxide react to release heat, and the cooler 17 cools the solution.

[0039] As a specific implementation of the nitrification alkali washing tail gas recycling device provided by the utility model, please refer to Figure 1 The sodium carbonate feeding tank 19 is connected to a sodium carbonate external supply pipeline 20, and a sodium carbonate feeding pipeline 21 is provided with a feeding pump 22.

[0040] For details, please refer to Figure 1 The sodium carbonate external supply pipeline 20 is connected to the sodium carbonate supply tank 19 to supply sodium carbonate solution to the sodium carbonate supply tank 19. The supply pump 22 is arranged on the sodium carbonate supply pipeline 21 to facilitate the discharge of the sodium carbonate solution into the alkali washing kettle 1, which helps to adjust the concentration of the sodium carbonate solution in the alkali washing kettle 1.

[0041] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A nitration alkali washing tail gas recycling device, characterized in that: The invention comprises an alkali cleaning kettle (1), an alkali cleaning tower (8) and a sodium carbonate feeding tank (19); the exhaust pipeline (2) of the alkali cleaning kettle (1) is connected to the alkali cleaning tower (8); the alkali cleaning tower (8) is provided with a sodium hydroxide discharge pipeline (9) and a sodium carbonate extraction pipeline (14); the other end of the sodium carbonate extraction pipeline (14) is connected to the sodium carbonate feeding tank (19); and the sodium carbonate feeding tank (19) is connected to the alkali cleaning kettle (1) via a sodium carbonate feeding pipeline (21).

2. A nitration alkali washing tail gas recycling device as claimed in claim 1, characterized in that: A nitrogen oxide absorption tower (5) is arranged between the alkali washing kettle (1) and the alkali washing tower (8), the exhaust pipeline (2) is connected to the nitrogen oxide absorption tower (5), and the gas outlet pipeline (6) of the nitrogen oxide absorption tower (5) is connected to the alkali washing tower (8).

3. A nitration alkali washing tail gas recycling device as claimed in claim 2, characterized in that: The exhaust pipeline (2) is provided with a compressor (3).

4. A nitration alkali washing tail gas recycling device as claimed in claim 2, characterized in that: The nitrogen oxide absorption tower (5) is provided with a water inlet pipeline (4) at the upper end and a liquid outlet pipeline (7) at the lower end.

5. The nitration alkali washing tail gas recycling device according to claim 2, characterized in that: The sodium hydroxide discharge pipeline (9) is arranged at the upper end of the alkali washing tower (8), and the gas outlet pipeline (6) is arranged at the lower end of the alkali washing tower (8).

6. The nitrification alkali washing tail gas recycling device according to claim 1, characterized in that: The sodium hydroxide discharge pipeline (9) is connected to a flow control valve (10), and the flow control valve (10) is connected to a water supply pipeline (11) and a sodium hydroxide supply pipeline (12).

7. The nitration alkali washing tail gas recycling device according to claim 1, characterized in that: The sodium carbonate extraction pipeline (14) is provided with a bottom circulation pump (15).

8. The nitration alkali washing tail gas recycling device according to claim 1, characterized in that: The sodium carbonate extraction pipeline (14) is provided with a sodium carbonate reflux pipeline (16), and the other end of the sodium carbonate reflux pipeline (16) is connected to the sodium hydroxide discharge pipeline (9).

9. A nitration alkali washing tail gas recycling device as claimed in claim 8, characterized in that: The sodium carbonate reflux pipeline (16) is provided with a cooler (17).

10. The nitration alkali washing tail gas recycling device according to claim 1, characterized in that: The sodium carbonate supply tank (19) is connected to a sodium carbonate external supply pipeline (20), and the sodium carbonate supply pipeline (21) is provided with a supply pump (22).

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