Equipment for recovering caprolactam in benzene residual liquid
By designing a equipment containing benzene residue extraction tower and benzene stripping tower, the problem of caprolactam failure in benzene residue in caprolactam industrial production was solved, and efficient resource recovery and energy-saving and emission reduction effects were achieved.
Patent Information
- Application Number
- CN202422037092.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-21
- Publication Date
- 2025-06-20
- Estimated Expiration
- 2034-08-21
AI Technical Summary
In the prior art, caprolactam in the benzene residue produced during the industrial production process of caprolactam cannot be effectively recovered, resulting in waste of resources.
A device including crude benzene feed assembly, benzene distillation assembly, benzene residue extraction assembly and benzene residue distillation assembly is designed. Through the combination of benzene residue extraction tower and benzene stripping tower, efficient recovery of caprolactam in benzene residue is achieved.
The recovery rate of caprolactam in benzene residue is achieved to reach more than 90%, saving energy and material consumption and reducing sewage treatment pressure.
Smart Images
Figure CN222998317U_ABST
Abstract
Description
Technical Field
[0001] This application relates to the technical field of chemical recycling, and particularly relates to a device for recovering caprolactam from benzene residual liquid. Background Art
[0002] In the industrial production process of caprolactam, the role of the benzene distillation unit is to treat the benzene-soluble impurities after the benzene extraction of caprolactam. Under normal conditions, the materials processed by benzene distillation contain 0.1 - 2 wt% of caprolactam, 50 mg / kg of cyclohexanone, 10 mg / kg of cyclohexanol, and a small amount of other benzene-soluble organic impurities, and the vast majority of the remaining components are benzene.
[0003] The benzene distillation unit generally consists of a set of two-effect rectification towers and a residual liquid distillation tower. The refined benzene at the top of the two-effect rectification tower and the residual liquid rectification tower is supplied to the benzene extraction tower. After most of the benzene is recovered from the heavy components at the bottom of the two-effect rectification tower by the residual liquid distillation tower, the heavy component materials at the bottom of the residual liquid distillation tower are sent to the waste liquid concentration process for incineration treatment.
[0004] The concentration of caprolactam in the heavy components discharged from the bottom of the second benzene distillation tower is high, and the content can account for 2 - 50%, and the flow rate is about 2 - 6 t / h, which has a certain recycling value. However, there is currently no device for recovering caprolactam from the heavy components, resulting in waste. Utility Model Content
[0005] The purpose of the embodiment of this application is to provide a device for recovering caprolactam from benzene residual liquid, including:
[0006] A crude benzene feeding component;
[0007] A benzene distillation component, whose feeding end is connected to the discharging end of the crude benzene feeding component, and is used for distilling crude benzene. The benzene distillation component includes a first benzene distillation tower and a second benzene distillation tower;
[0008] A benzene residual liquid extraction component, which includes:
[0009] A benzene residual liquid extraction tower feed cooler, whose feeding end is connected to the discharging end of the second benzene distillation tower, and is used for cooling the benzene residual liquid generated by the benzene distillation component;
[0010] A benzene residual liquid extraction tower, whose feeding end is connected to the discharging end of the benzene residual liquid extraction tower feed cooler, and is used for extracting the cooled benzene residual liquid. The discharging end of the bottom of the benzene residual liquid extraction tower is connected to a benzene stripping tower for recovering caprolactam;
[0011] A benzene residual liquid distillation component, whose feeding end is connected to the discharging end of the top of the benzene residual liquid extraction tower, and is used for distilling the impurity benzene overflowing through the discharging end of the top.
[0012] As an optional embodiment, the feed end of the benzene residue distillation assembly is connected to the discharge end of the second benzene distillation column for distilling the benzene residue generated by the benzene distillation assembly.
[0013] As an optional embodiment, a first thermometer is provided on the pipeline between the benzene distillation assembly and the feed end of the benzene residue extraction tower feed cooler for detecting the temperature of the benzene residue feed; a second thermometer and a first flowmeter are provided on the pipeline between the discharge end of the benzene residue extraction tower feed cooler and the feed end of the benzene residue extraction tower. The second thermometer is used to detect the temperature of the benzene residue after cooling, and the first flowmeter is used to detect the flow rate of the cooled benzene residue entering the benzene residue extraction tower.
[0014] As an optional embodiment, a fourth thermometer and a first pressure gauge for respectively detecting the bottom temperature and pressure are provided at the bottom of the benzene residue extraction tower; a pressure gauge assembly and an interface level gauge assembly for respectively detecting the top pressure and liquid level height are provided at the top of the benzene residue extraction tower.
[0015] As an optional embodiment, the pressure gauge assembly includes a second pressure gauge and a third pressure gauge. The second pressure gauge is used to remotely detect the pressure at the top of the tower, and the third pressure gauge is used to on-site detect the pressure at the top of the tower; the interface level gauge assembly includes a first interface level gauge and a second interface level gauge. The first interface level gauge is used to on-site detect the liquid level height at the top of the tower, and the second interface level gauge is used to remotely detect the liquid level height at the top of the tower.
[0016] As an optional embodiment, a first valve is provided on the pipeline between the bottom discharge end of the benzene residue extraction tower and the benzene stripping tower for controlling the interface level of the benzene residue extraction tower; a second valve is provided on the pipeline between the top discharge end of the benzene residue extraction tower and the feed end of the benzene residue distillation assembly for controlling the operating pressure of the benzene residue extraction tower.
[0017] As an optional embodiment, a third valve is provided at the top of the benzene residue extraction tower for discharging materials.
[0018] As an optional embodiment, a fourth valve, a second flowmeter for detecting the demineralized water flow rate, and a fourth valve for adjusting the demineralized water flow rate are provided on the pipeline between the liquid inlet end of the extraction water of the benzene residue extraction tower and the demineralized water pipeline.
[0019] As an optional embodiment, a third thermometer for detecting the temperature of the circulating water return is provided on the pipeline between the liquid outlet end of the coolant of the benzene residue extraction tower feed cooler and the circulating water return pipeline.
[0020] The beneficial effects of the embodiments of the present application are as follows:
[0021] This application is reasonably designed. By adding a benzene residue extraction component, the recovery rate of caprolactam in the benzene residue can reach over 90%, and there are no energy costs such as steam and electricity generated. It saves material consumption and can reduce the pressure on sewage treatment.
[0022] This application utilizes the good water solubility of caprolactam. After the second benzene distillation tower, a benzene residue cooler and a benzene residue extraction tower are added. The caprolactam in the bottom liquid of the second benzene distillation tower is extracted with the by-product process condensate in the equipment. The aqueous caprolactam solution at the bottom of the benzene residue extraction tower is sent to the benzene stripping tower for the recovery of caprolactam, and the overflow benzene containing impurities at the top of the benzene residue extraction tower is sent to the benzene residue distillation tower for further recovery of benzene therein. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] Figure 1 It is the process flow diagram of the equipment for recovering caprolactam from benzene residue in the embodiment of this application;
[0024] Figure 2 It is the process flow diagram of the benzene residue extraction component in the embodiment of this application.
[0025] REFERENCE SIGNS:
[0026] A1, the first benzene distillation tower; A2, the second benzene distillation tower;; A5, the benzene residue distillation tower; A6, the benzene buffer tank; A7, the discharge pump of the second benzene distillation tower; A8, the benzene pump tank; A9, the residue pump; A10, the benzene discharge pump; A11, the benzene distillation cooler; A12, the feed heat exchanger of benzene distillation; A13, the benzene distillation condenser; A14, the top condenser of the benzene residue distillation tower; A15, the feed heater of benzene distillation;
[0027] B1, the feed cooler of the benzene residue extraction tower; B2, the benzene residue extraction tower; B3, the first thermometer; B4, the third thermometer; B5, the second thermometer; B6, the first flowmeter; B7, the fourth thermometer; B8, the first pressure gauge; B9, the first valve; B10, the second flowmeter; B11, the second pressure gauge; B12, the third pressure gauge; B13, the first interface gauge; B14, the second interface gauge; B15, the second valve; B16, the third valve; B17, the fourth valve. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0028] Reference is made herein to the various embodiments and features of this application with reference to the drawings.
[0029] It should be understood that various modifications can be made to the embodiments applied herein. Therefore, the above specification should not be regarded as a limitation, but only as an example of the embodiments. Those skilled in the art will think of other modifications within the scope and spirit of this application.
[0030] The accompanying drawings, which are included in and form a part of this specification, illustrate embodiments of the present application and, together with the general description of the present application given above and the detailed description of the embodiments given below, serve to explain the principles of the present application.
[0031] These and other features of the present application will become apparent from the following description of the preferred forms of the embodiments, given by way of non-limiting example, with reference to the accompanying drawings.
[0032] It should also be understood that although the present application has been described with reference to some specific examples, those skilled in the art can surely implement many other equivalent forms of the present application.
[0033] When taken in conjunction with the accompanying drawings, the above and other aspects, features, and advantages of the present application will become more apparent in view of the following detailed description.
[0034] Specific embodiments of the present application will be described hereinafter with reference to the accompanying drawings; however, it should be understood that the embodiments claimed are merely examples of the present application, which can be implemented in various ways. Well-known and / or repetitive functions and structures are not described in detail to avoid obscuring the present application with unnecessary or redundant details. Therefore, the specific structural and functional details claimed herein are not intended to be limiting, but rather are merely a basis and representative basis for the claims to teach those skilled in the art to use the present application in substantially any suitable detailed structure in a variety of ways.
[0035] This specification may use the phrases "in one embodiment", "in another embodiment", "in yet another embodiment", or "in other embodiments", each of which may refer to one or more of the same or different embodiments according to the present application.
[0036] Benzene is an extractant in the refining process of caprolactam, used to dissolve benzene-soluble impurities in crude caprolactam. Benzene is recycled within the system, and the benzene-soluble impurities in crude caprolactam are sent to the utility tank area as a heavy component residue during the benzene distillation process. The recycled benzene is allowed to stand in the crude benzene tank to remove a small amount of water entrained in the benzene, and the crude benzene is sent to the benzene distillation system through a benzene transfer pump.
[0037] That is, industrial-scale caprolactam production is mainly carried out by the rearrangement reaction of cyclohexanone oxime under the catalytic action of fuming sulfuric acid. The reaction solution is reacted with ammonia to remove the sulfuric acid therein to obtain amide oil, the amide oil is extracted with benzene to obtain a caprolactam benzene solution containing certain impurities, and the caprolactam benzene solution is back-extracted with process water to remove benzene-soluble impurities, obtaining an aqueous solution of caprolactam in the extraction phase and a raffinate crude benzene solution containing impurities and a certain amount of caprolactam.
[0038] Among them, the aqueous solution of caprolactam is refined through subsequent hydrogenation, evaporation, and distillation processes of the device to obtain the product caprolactam. The crude benzene liquid is refined through a double-effect distillation operation to obtain refined benzene and benzene residue liquid. The refined benzene is sent to the production device for recycling, and the benzene residue liquid is further distilled to remove part of the benzene and then incinerated. However, the caprolactam in the benzene residue liquid cannot be recovered.
[0039] In view of the above, the embodiment of the present application provides a device for recovering caprolactam from benzene residue liquid, as Figure 1 and Figure 2 shown. The device includes a crude benzene feeding component, a benzene distillation component, a benzene residue liquid extraction component, and a benzene residue liquid distillation component. The crude benzene feeding component is used to transport crude benzene into the benzene distillation component.
[0040] The feeding end of the benzene distillation component is connected to the discharging end of the crude benzene feeding component and is used for distilling crude benzene. Among them, in order to achieve full utilization of energy, the benzene distillation component is designed according to a two-effect evaporation, that is, the benzene distillation component includes a first benzene distillation tower A1 and a second benzene distillation tower A2.
[0041] The benzene residue liquid extraction component includes a benzene residue liquid extraction tower feed cooler B1 and a benzene residue liquid extraction tower B2. The feeding end of the benzene residue liquid extraction tower feed cooler B1 is connected to the discharging end of the second benzene distillation tower A2 and is used for cooling the benzene residue liquid generated by the benzene distillation component. The feeding end of the benzene residue liquid extraction tower B2 is connected to the discharging end of the benzene residue liquid extraction tower feed cooler B1 and is used for extracting the cooled benzene residue liquid. The bottom discharging end of the benzene residue liquid extraction tower B2 is connected to a benzene stripping tower and is used for recovering caprolactam. Among them, the benzene stripping tower is connected to a ammonium sulfate device.
[0042] The feeding end of the benzene residue liquid distillation component is connected to the top discharging end of the benzene residue liquid extraction tower B2 and is used for distilling the impurity benzene overflowing through the top discharging end.
[0043] In this embodiment, the crude benzene feeding component includes a benzene storage tank, a benzene distillation feeding heat exchanger A12, and a benzene distillation feeding heater A15. Specifically, the crude benzene drawn from the benzene storage tank enters the tube side of the benzene distillation feeding heat exchanger A12 through a pipeline and is preheated through the tube side of the benzene distillation feeding heater A15.
[0044] The benzene distillation component further includes a benzene buffer tank A6, a second benzene distillation tower discharging pump A7, a benzene distillation cooler A11, and a benzene distillation condenser A13. The benzene buffer tank A6 is arranged between the first benzene distillation tower A1 and the second benzene distillation tower A2. The second benzene distillation tower discharging pump A7 is arranged between the second benzene distillation tower A2 and the benzene residue liquid extraction tower feed cooler B1.
[0045] The benzene residue distillation assembly includes a benzene residue distillation column A5, a residue pump A9, and a benzene residue distillation column top condenser A14. The feed end of the benzene residue distillation column A5 is connected to the discharge end of the top of the benzene residue extraction column B2, and the discharge end of its column kettle is connected to the residue pump A9 for transporting the materials at the column kettle of the benzene residue distillation column A5. The discharge end of the top of the benzene residue distillation column A5 is connected to the benzene residue distillation column top condenser A14.
[0046] The equipment further includes a benzene pump tank A8 and a benzene discharge pump A10. The feed end of the benzene pump tank A8 is connected to the benzene distillation cooler A11, and its discharge end is connected to the benzene discharge pump A10 for transporting refined benzene.
[0047] Specifically, the preheated crude benzene enters the benzene distillation column A1. The heavy phase at the column kettle of the benzene distillation column A1 enters the benzene distillation column A2. The benzene distillation column A1 uses steam as the heating heat source for the evaporation of crude benzene. The benzene vapor at the top of the benzene distillation column A1 enters the reboiler of the benzene distillation column A2 as the heating source for the benzene distillation column A2. The liquid-phase refined benzene after heating the benzene distillation column A2 enters the shell side of the benzene distillation feed heater A15 to exchange heat with the crude benzene in the tube side, and then enters the shell side of the benzene distillation cooler A11 to exchange heat with circulating water and is cooled to 41°C. The cooled refined benzene flows into the benzene pump tank A8 and is sent to the extraction system through the benzene discharge pump A10, with a small amount being used as the reflux of the benzene distillation column A2.
[0048] The uncooled benzene vapor after heating the benzene distillation column A2 is combined with the benzene vapor at the top of the benzene distillation column A2, and then passes through the shell sides of the benzene distillation feed heat exchanger A12 and the benzene distillation condenser A13 and is cooled by secondary circulating water. The refined benzene condensate enters the shell side of the benzene distillation cooler A11, and the gas phase enters the tail gas treatment system.
[0049] The bottom material of the benzene distillation column A1 flows into the benzene distillation column A2 by the action of pressure difference. The benzene residue at the column kettle of the benzene distillation column A2 is transported to the shell side of the benzene residue extraction column feed cooler B1 through the benzene distillation column A2 discharge pump A7, exchanges heat with circulating water and is cooled, and then enters the benzene residue extraction column B1 through the pipeline. The process condensate (i.e., demineralized water) extracts caprolactam from the benzene residue. The caprolactam aqueous solution at the column kettle is sent to the benzene stripping column and the ammonium sulfate unit for recovery, and the remaining benzene flows into the benzene residue distillation column A5 from the top for the final evaporation and recovery of benzene. The benzene vapor of the benzene residue distillation column A5 enters the shell side of the benzene residue distillation column top condenser A14 to exchange heat with circulating water and condenses. The refined benzene condensate flows into the benzene pump tank A8 by itself, and the gas phase enters the tail gas treatment system.
[0050] As an optional embodiment, the feed end of the benzene residue distillation assembly is connected to the discharge end of the benzene distillation column A2 for distilling the benzene residue generated by the benzene distillation assembly, so as to directly feed the benzene residue at the column kettle of the benzene distillation column A2 into the benzene residue distillation assembly when the benzene residue extraction assembly cannot be used normally.
[0051] As an optional embodiment, a first thermometer B3 is provided on the pipeline between the benzene distillation assembly and the feed end of the benzene residue extraction tower feed cooler B1 for detecting the temperature of the benzene residue feed.
[0052] A second thermometer B5 and a first flowmeter B6 are provided on the pipeline between the discharge end of the benzene residue extraction tower feed cooler B1 and the feed end of the benzene residue extraction tower B2. The second thermometer B5 is used to detect the temperature of the benzene residue after cooling, and the first flowmeter B6 is used to detect the flow rate of the cooled benzene residue entering the benzene residue extraction tower B2.
[0053] As an optional embodiment, a fourth thermometer B7 and a first pressure gauge B8 for respectively detecting the bottom temperature and pressure are provided at the bottom of the benzene residue extraction tower B2. The bottom temperature of the benzene residue extraction tower B2 is generally 30 - 45 °C.
[0054] A pressure gauge assembly and an interface level gauge assembly for respectively detecting the top pressure and liquid level height are provided at the top of the benzene residue extraction tower B2.
[0055] Specifically, the pressure gauge assembly includes a second pressure gauge B11 and a third pressure gauge B12. The second pressure gauge B11 is used to remotely detect the pressure at the top of the tower, and the third pressure gauge B12 is used to on-site detect the pressure at the top of the tower. The operating pressure of the benzene residue extraction tower B2 is generally controlled at a slightly positive pressure, with a pressure of 1.5 - 30 kPa.
[0056] The interface level gauge assembly includes a first interface level gauge B13 and a second interface level gauge B14. The first interface level gauge B13 is used to on-site detect the liquid level height at the top of the tower, and the second interface level gauge B14 is used to remotely detect the liquid level height at the top of the tower to determine the phase separation situation of the organic phase and the inorganic phase in the benzene residue extraction tower B2.
[0057] As an optional embodiment, a first valve B9 is provided on the pipeline between the bottom discharge end of the benzene residue extraction tower B2 and the benzene stripping tower for controlling the interface level of the benzene residue extraction tower B2. The first valve B9 is a pneumatic control valve for controlling the interface level of the benzene residue extraction tower B2 at 5 - 80% of the maximum liquid level height of the tower.
[0058] A second valve B15 is provided on the pipeline between the top discharge end of the benzene residue extraction tower B2 and the feed end of the benzene residue distillation assembly for controlling the operating pressure of the benzene residue extraction tower B2. The second valve B15 is a pneumatic control valve for controlling the operating pressure of the benzene residue extraction tower B2 at 1.5 - 30 KPa.
[0059] As an alternative embodiment, a third valve B16 is provided at the top of the benzene residue extraction tower B2 for discharging materials. The third valve B16 is a safety valve, and when the pressure at the top of the benzene residue extraction tower B2 exceeds 0.15 MPa, the materials are discharged to a safe location.
[0060] As an alternative embodiment, a second flowmeter B10 for detecting the flow rate of demineralized water and a fourth valve B17 for adjusting the flow rate of demineralized water are provided on the pipeline between the liquid inlet end of the extraction water of the benzene residue extraction tower B2 and the demineralized water pipeline.
[0061] Specifically, the upper part of the benzene residue extraction tower B2 is connected to the demineralized water pipeline. Demineralized water is used as the continuous phase to extract caprolactam from the benzene residue. The second flowmeter B10 and the fourth valve B17 provided on the pipeline connected to the demineralized water pipeline are respectively used to measure and adjust the flow rate of demineralized water. Among them, the flow rates of demineralized water and benzene residue are adjusted according to a preset ratio, and the mass ratio of demineralized water / benzene residue flow rate is 0.1 - 0.5.
[0062] As an alternative embodiment, a third thermometer B4 for detecting the temperature of the circulating water return is provided on the pipeline between the liquid outlet end of the coolant of the benzene residue extraction tower feed cooler B1 and the circulating water return pipeline.
[0063] As Figure 2 shown, the working process of the benzene residue extraction assembly is as follows:
[0064] Since the concentration of caprolactam in the benzene residue produced by the benzene distillation column A2 is relatively high, the benzene residue from the bottom of the benzene distillation column A2 is sent through a pipeline to the benzene residue extraction tower feed cooler B1.
[0065] According to the concentration of caprolactam in the benzene residue, generally the benzene residue feed temperature is 85 - 120 °C. The benzene residue extraction tower feed cooler B1 is connected to the circulating water supply and the circulating water return pipeline to cool the benzene residue.
[0066] The cooled benzene residue enters the bottom of the benzene residue extraction tower B2. The temperature of the benzene residue after cooling is controlled at 30 - 45 °C, and the flow rate of the benzene residue entering the benzene residue extraction tower B2 is generally 1000 - 4500 kg / h.
[0067] The benzene residue extraction tower B2 extracts the benzene residue with demineralized water. The aqueous solution containing caprolactam is transported from the bottom of the benzene residue extraction tower B2 to the benzene stripper to recover benzene, and then sent to the ammonium sulfate unit for subsequent treatment.
[0068] The organic phase at the top of the benzene residue extraction tower B2 overflows back to the benzene residue distillation tower A5 to further recover the benzene therein. The residue after distillation in the benzene residue distillation tower A5 is sent to the waste liquid concentration device.
[0069] During the operation of the benzene residue extraction component of this application, the extraction water used is the by-product triple-effect process condensate in this device, which does not generate additional desalted water costs, does not consume electricity, and only generates the cost of circulating water. Among them, the expected consumption of circulating water is 20 t / h, and the operating cost is 20 * 8000 * 0.19 = 30,400 yuan / year.
[0070] After the operation of this application, the caprolactam content in the caprolactam aqueous solution in the bottom of the extraction tower is about 10%, the flow rate is 1000 kg / h, 100 kg of caprolactam is recovered per hour, and the annual operation is 8000 hours. 800 tons of caprolactam can be recovered. The specific income situation is as follows:
[0071]
[0072] Total benefits: 960.67 - 3.04 = 957.63 ten thousand yuan / year.
[0073] In summary, after the improvement of the new process, the benefits are obvious. 800 tons of caprolactam are saved annually, the annual comprehensive income is 9.5763 million yuan, and at the same time, the discharge of high-COD wastewater can be reduced, and the environmental protection treatment pressure can be reduced.
[0074] The above embodiments are only exemplary embodiments of this application and are not used to limit this application. The protection scope of this application is defined by the claims. Those skilled in the art can make various modifications or equivalent replacements within the essence and protection scope of this application, and such modifications or equivalent replacements should also be regarded as falling within the protection scope of this application.
Claims
1. A device for recovering caprolactam from benzene residue, characterized in that: include: Crude benzene feed assembly; A benzene distillation component, whose feed end is connected to the discharge end of the crude benzene feed component, is used to distill crude benzene, and the benzene distillation component includes a first benzene distillation tower and a second benzene distillation tower; A benzene residue extraction assembly, comprising: A benzene residue extraction tower feed cooler, whose feed end is connected to the discharge end of the second benzene distillation tower, and is used to cool the benzene residue generated by the benzene distillation component; A benzene residue extraction tower, whose feed end is connected to the discharge end of the benzene residue extraction tower feed cooler, for extracting the cooled benzene residue, and the tower bottom discharge end of the benzene residue extraction tower is connected to a benzene stripping tower, for recovering caprolactam; The benzene residue distillation component has a feed end connected to the top discharge end of the benzene residue extraction tower and is used for distilling impurity benzene overflowing through the top discharge end.
2. The device for recovering caprolactam from benzene residue according to claim 1, characterized in that: The feed end of the benzene residue distillation component is connected to the discharge end of the second benzene distillation tower, and is used to distill the benzene residue generated by the benzene distillation component.
3. The device for recovering caprolactam from benzene residue according to claim 1, characterized in that: A first thermometer is provided on the pipeline between the benzene distillation component and the feed end of the benzene residual liquid extraction tower feed cooler, for detecting the temperature of the benzene residual liquid feed; a second thermometer and a first flowmeter are provided on the pipeline between the discharge end of the benzene residual liquid extraction tower feed cooler and the feed end of the benzene residual liquid extraction tower, the second thermometer is used to detect the temperature of the benzene residual liquid after cooling, and the first flowmeter is used to detect the flow rate of the cooled benzene residual liquid entering the benzene residual liquid extraction tower.
4. The device for recovering caprolactam from benzene residue according to claim 1, characterized in that: The bottom of the benzene residual liquid extraction tower is provided with a fourth thermometer and a first pressure gauge for respectively detecting the temperature and pressure of the tower bottom; the top of the benzene residual liquid extraction tower is provided with a pressure gauge assembly and a level gauge assembly for respectively detecting the tower top pressure and liquid level height.
5. The device for recovering caprolactam from benzene residue as claimed in claim 4, characterized in that: The pressure gauge assembly includes a second pressure gauge and a third pressure gauge, the second pressure gauge is used to remotely detect the pressure at the top of the tower, and the third pressure gauge is used to detect the pressure at the top of the tower on site; the level gauge assembly includes a first level gauge and a second level gauge, the first level gauge is used to detect the liquid level height at the top of the tower on site, and the second level gauge is used to remotely detect the liquid level height at the top of the tower.
6. The device for recovering caprolactam from benzene residue according to claim 1, characterized in that: A first valve is provided on the pipeline between the bottom discharge end of the benzene residue extraction tower and the benzene stripping tower, which is used to control the interface position of the benzene residue extraction tower; a second valve is provided on the pipeline between the top discharge end of the benzene residue extraction tower and the feed end of the benzene residue distillation component, which is used to control the operating pressure of the benzene residue extraction tower.
7. The device for recovering caprolactam from benzene residue according to claim 4, characterized in that: A third valve is provided on the top of the benzene residue extraction tower for discharging materials.
8. The device for recovering caprolactam from benzene residue according to claim 1, characterized in that: The pipeline between the inlet end of the extraction water of the benzene residual liquid extraction tower and the desalted water pipeline is provided with a second flow meter for detecting the flow of desalted water and a fourth valve for adjusting the flow of desalted water.
9. The device for recovering caprolactam from benzene residue according to claim 1, characterized in that: A third temperature meter for detecting the return temperature of circulating water is provided on the pipeline between the liquid outlet of the coolant of the feed cooler of the benzene residual liquid extraction tower and the return water pipeline of circulating water.