Caprolactam recovery device

Abstract

The utility model discloses a device for recovering caprolactam, which relates to the technical field of caprolactam recovery, and comprises a crude benzene tank for water washing and alkali washing operation, the bottom of the crude benzene tank is provided with a crude benzene tank bottom layer liquid pipeline, one end of the crude benzene tank bottom layer liquid pipeline is fixedly connected with a bottom layer liquid pump, and the other end of the crude benzene tank bottom layer liquid pipeline is fixedly connected with a bottom layer liquid pump. The output end of the bottom-layer liquid pump is fixedly connected with a bottom-layer liquid pump outlet pipeline, the tail gas absorption tower is arranged on one side of the extraction tower, and the extraction tower is arranged on one side of the tail gas absorption tower. According to the caprolactam recycling device, pipelines are changed on the basis of the technological process in the prior art, after regular alkali washing and water washing are conducted on crude benzene, caprolactam and a sodium hydroxide solution can be recycled, and therefore steam consumption and hazardous waste are reduced, and the caprolactam recycling device is wide in application range and low in cost. And the device can be suitable for various recyclable environments, and is simple in structure and relatively good in practicability.

Description

Technical Field

[0001] The utility model relates to the technical field of caprolactam recovery, in particular to a device for recovering caprolactam. Background Art

[0002] Currently, in the caprolactam production process, after crude benzene is distilled to obtain refined benzene, the refined benzene is used as a solvent to extract the crude amide oil to obtain a benzene-hexyl solution, thereby removing water-soluble impurities in the crude amide oil. The water extraction section is a process in which process water is used as a solvent to extract the benzene-hexyl solution to obtain a caprolactam aqueous solution, while the raffinate benzene is returned to the distillation and recycled process. The benzene in the raffinate phase may contain caprolactam substances that have not been completely extracted. The caprolactam substances will continue to circulate with the benzene in the benzene distillation system. Because caprolactam is a heat-sensitive material, the caprolactam in the benzene in the continuous production process will polymerize and form scale in the benzene distillation tower and heat exchanger, affecting the benzene distillation heat exchange effect. The existing technology is to regularly wash the crude benzene with alkali (sodium hydroxide) and water, dissolve the caprolactam and acidic impurities in the crude benzene in the aqueous phase, and send the wastewater to be incinerated. However, this technology will cause caprolactam loss and has poor practicality.

[0003] Based on this, a device for recovering caprolactam is now provided, which can eliminate the disadvantages of the existing technical solutions. Utility Model Content

[0004] The purpose of the utility model is to provide a device for recovering caprolactam, so as to solve the problem of caprolactam loss in the background technology.

[0005] To achieve the above objectives, the present invention provides the following technical solutions:

[0006] A device for recovering caprolactam comprises a crude benzene tank for performing water washing and alkali washing operations, a crude benzene tank bottom liquid pipeline is provided at the bottom of the crude benzene tank, one end of the crude benzene tank bottom liquid pipeline is fixedly connected to a bottom liquid pump, and the output end of the bottom liquid pump is fixedly connected to a bottom liquid pump outlet pipeline, and further comprises a tail gas absorption tower and a hexane extraction tower, the tail gas absorption tower is arranged on one side of the hexane extraction tower, and the hexane extraction tower is arranged on one side of the tail gas absorption tower.

[0007] Preferably, the top of the tail gas absorption tower is connected to the bottom liquid pump outlet pipeline, the interior of the tail gas absorption tower is set as a crude amide oil solution, the bottom of the tail gas absorption tower is connected to the tail gas absorption tower discharge pipeline, and the other end of the tail gas absorption tower discharge pipeline is connected to the top of the hexane extraction tower.

[0008] Preferably, a hexane extraction tower discharge pipeline is provided at the bottom of the hexane extraction tower, the other end of the hexane extraction tower discharge pipeline is fixedly connected to a waste liquid pump, and the output end of the waste liquid pump is fixedly provided with a waste liquid pump outlet pipeline.

[0009] Preferably, a process water pipeline is provided on the left side of the crude benzene tank.

[0010] Preferably, one side of the process water pipeline is connected to a first sodium hydroxide solution pipeline.

[0011] Preferably, a pH meter is provided on the outside of the tail gas absorption tower discharge pipeline.

[0012] Preferably, one side of the tail gas absorption tower discharge pipeline is connected to a second sodium hydroxide solution pipeline, and the second sodium hydroxide solution pipeline is arranged on the side of the pH meter away from the hexane extraction tower.

[0013] Preferably, control valves are provided on the outsides of the bottom liquid pump outlet pipeline, the tail gas absorption tower discharge pipeline and the hexane extraction tower discharge pipeline.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0015] The utility model provides a device for recovering caprolactam, and makes pipeline changes on the process flow of the existing technology, so that after the crude benzene is regularly washed with alkali (sodium hydroxide) and water, the caprolactam and sodium hydroxide solution can be recovered, thereby reducing the consumption of steam and the generation of hazardous waste. The device has a wide range of applications and can be applied to a variety of recycling and reuse environments. It has a simple structure and good practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural diagram of the present utility model.

[0017] Figure 2 It is a schematic structural diagram of the utility model as a whole.

[0018] Notes on the accompanying drawings: crude benzene tank 10, crude benzene tank bottom liquid pipeline 11, bottom liquid pump 12, bottom liquid pump outlet pipeline 13, process water pipeline 14, first sodium hydroxide solution pipeline 15, tail gas absorption tower 20, tail gas absorption tower discharge pipeline 21, pH meter 22, second sodium hydroxide solution pipeline 23, hexane extraction tower 30, hexane extraction tower discharge pipeline 31, waste liquid pump 32, waste liquid pump outlet pipeline 33. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0020] Example 1

[0021] In this embodiment, if Figure 1-Figure 2As shown, a device for recovering caprolactam includes a crude benzene tank 10 for performing water washing and alkali washing operations, a crude benzene tank bottom liquid pipeline 11 is provided at the bottom of the crude benzene tank 10, one end of the crude benzene tank bottom liquid pipeline 11 is fixedly connected to a bottom liquid pump 12, and the output end of the bottom liquid pump 12 is fixedly connected to a bottom liquid pump outlet pipeline 13, and also includes a tail gas absorption tower 20, the tail gas absorption tower 20 is arranged on one side of the hexane extraction tower 10, and is used to absorb benzene substances and recover caprolactam aqueous solution and sodium hydroxide solution, and a hexane extraction tower 30, the hexane extraction tower 30 is arranged on one side of the tail gas absorption tower 20. Before the device for recovering caprolactam is put into use, the device is first checked to see if it can be used normally, and then the control valve is adjusted to put the device into a standby state;

[0022] Among them Figure 2 As shown, the top of the tail gas absorption tower 20 is connected to the bottom liquid pump outlet pipeline 13, the interior of the tail gas absorption tower 20 is set to a crude amide oil solution, the bottom of the tail gas absorption tower 20 is connected to the tail gas absorption tower discharge pipeline 21, and the other end of the tail gas absorption tower discharge pipeline 21 is connected to the top of the hexane extraction tower 30. The tail gas absorption tower 20 is convenient for absorbing the benzene substance entrained in the bottom liquid pump 12;

[0023] Among them Figure 2 As shown, a hexane extraction tower discharge pipeline 31 is provided at the bottom of the hexane extraction tower 30, and the other end of the hexane extraction tower discharge pipeline 31 is fixedly connected to a waste liquid pump 32, and a waste liquid pump outlet pipeline 33 is fixedly provided at the output end of the waste liquid pump 32, so as to facilitate the transportation of remaining impurities through the waste liquid pump outlet pipeline 33, save steam consumption, and avoid the generation of alkali ash and alkali residue after the incineration of the waste liquid, which leads to the generation of hazardous waste;

[0024] Among them Figure 2 As shown, a process water pipeline 14 is provided on the left side of the crude benzene tank 10, and the process water pipeline 14 is connected to the middle of the crude benzene tank 10 to facilitate water washing operations;

[0025] Among them Figure 2 As shown, one side of the process water pipeline 14 is connected to a first sodium hydroxide solution pipeline 15, and the first sodium hydroxide solution pipeline 15 is connected to the middle of the crude benzene tank 10 to facilitate the alkaline washing operation;

[0026] Among them Figure 2 As shown, a pH meter 22 is provided on the outside of the tail gas absorption tower discharge pipeline 21 to display the pH value of the substance inside the tail gas absorption tower discharge pipeline 21;

[0027] Among them Figure 2 As shown, one side of the tail gas absorption tower discharge pipeline 21 is connected to a second sodium hydroxide solution pipeline 23, and the second sodium hydroxide solution pipeline 23 is arranged on the side of the pH meter 22 away from the extraction tower 30 to ensure the normal operation of the device;

[0028] Example 2

[0029] The difference from Example 1 is that Figure 2 As shown, control valves are provided on the outside of the bottom liquid pump outlet pipeline 13, the tail gas absorption tower discharge pipeline 21 and the hexane extraction tower discharge pipeline 31 to facilitate the control of the content and rate, limit the flow rate, and avoid errors caused by excessive or insufficient input.

[0030] Working principle: The caprolactam aqueous solution and acidic impurities in the crude benzene after water washing and alkali washing in the crude benzene tank 10 are sent to the wastewater equipment for waste liquid incineration through the bottom liquid pump outlet pipeline 13. Instead, they first enter the tail gas absorption tower 20 and then pass through the bottom liquid pump outlet pipeline 13. Before the crude amide oil enters the hexane extraction tower 30, alkali should be added through the second sodium hydroxide solution pipeline 23 to adjust the pH index of the crude amide oil so that the pH meter 22 displays a value of 6 to 7. The bottom liquid pump outlet pipeline 13 is now connected to the tail gas absorption tower 20 to facilitate the absorption of benzene substances entrained in the bottom liquid pump 12, and to recover the caprolactam aqueous solution and sodium hydroxide solution after water washing and alkali washing in the crude benzene tank 10, thereby reducing the consumption of caprolactam and sodium hydroxide. The remaining impurities pass through the residual phase of the hexane extraction tower 30 and are then sent to the wastewater for waste liquid incineration through the waste liquid pump outlet pipeline 33, saving steam consumption and avoiding the generation of alkali ash and alkali residue after waste liquid incineration, which leads to the generation of hazardous waste.

[0031] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A device for recovering caprolactam, comprising a crude benzene tank (10) for performing water washing and alkali washing operations, wherein a crude benzene tank bottom liquid pipeline (11) is provided at the bottom of the crude benzene tank (10), one end of the crude benzene tank bottom liquid pipeline (11) is fixedly connected to a bottom liquid pump (12), and the output end of the bottom liquid pump (12) is fixedly connected to a bottom liquid pump outlet pipeline (13); It is characterized by: It also includes a tail gas absorption tower (20), which is arranged on one side of the hexane extraction tower (10); The hexane extraction tower (30) is arranged on one side of the tail gas absorption tower (20).

2. The device for recovering caprolactam according to claim 1, characterized in that The top of the tail gas absorption tower (20) is connected to the bottom liquid pump outlet pipeline (13), the interior of the tail gas absorption tower (20) is set as a crude amide oil solution, the bottom of the tail gas absorption tower (20) is connected to the tail gas absorption tower discharge pipeline (21), and the other end of the tail gas absorption tower discharge pipeline (21) is connected to the top of the hexane extraction tower (30).

3. The device for recovering caprolactam according to claim 2, characterized in that A hexane extraction tower discharge pipeline (31) is provided at the bottom of the hexane extraction tower (30), the other end of the hexane extraction tower discharge pipeline (31) is fixedly connected to a waste liquid pump (32), and a waste liquid pump outlet pipeline (33) is fixedly provided at the output end of the waste liquid pump (32).

4. The device for recovering caprolactam according to claim 1, characterized in that A process water pipeline (14) is provided on the left side of the crude benzene tank (10).

5. The device for recovering caprolactam according to claim 4, characterized in that One side of the process water pipeline (14) is connected to a first sodium hydroxide solution pipeline (15).

6. The device for recovering caprolactam according to claim 2, characterized in that: A pH meter (22) is provided on the outside of the tail gas absorption tower discharge pipeline (21).

7. The device for recovering caprolactam according to claim 6, characterized in that One side of the tail gas absorption tower discharge pipeline (21) is connected to a second sodium hydroxide solution pipeline (23), and the second sodium hydroxide solution pipeline (23) is arranged on a side of the pH meter (22) away from the hexane extraction tower (30).

8. The device for recovering caprolactam according to claim 3, characterized in that: Control valves are provided on the outsides of the bottom liquid pump outlet pipeline (13), the tail gas absorption tower discharge pipeline (21) and the hexane extraction tower discharge pipeline (31).

Images