Urotropin production plant

Abstract

The utility model discloses a kind of urotropin production devices, including reaction kettle, vaporizer, filter, circulating pump, heat exchanger, formaldehyde feed line, ammonia source feed line, first control valve, second control valve, near-infrared online analyzer and controller;Wherein, the formaldehyde feed line is connected with the reaction kettle, the first control valve is connected in the formaldehyde feed line, the ammonia source feed line is connected with the feed inlet of the vaporizer, the discharge port of the vaporizer is connected with the inlet of the filter, the outlet of the filter is connected with the reaction kettle, the second control valve is connected in the ammonia source feed line, the inlet of the circulating pump is connected with the reaction kettle.The utility model can accurately determine reaction endpoint, can avoid reaction endpoint determination lag, and then can stop passing in ammonia in time to avoid ammonia passing in excess to cause waste, also can avoid worker contact ammonia to reduce security risk and improve operating safety.

Description

Technical Field

[0001] This utility model relates to a hexamethylenetetramine production apparatus. Background Technology

[0002] Currently, urotropine can be produced by reacting formaldehyde solution with ammonia. A Chinese patent (CN222789248U) discloses an apparatus for producing urotropine using formaldehyde solution and ammonia. One method for preparing urotropine involves adding a certain amount of formaldehyde solution to a reaction vessel, then introducing ammonia gas to react with the formaldehyde solution to produce urotropine. The reaction endpoint is reached when all the formaldehyde solution in the vessel has been consumed, at which point the introduction of ammonia gas must be stopped. Currently, many companies rely on manual, periodic sampling and testing of the pH value of the reaction solution to determine whether the reaction endpoint has been reached. This method is prone to delays in determining the endpoint, potentially leading to excessive ammonia gas being introduced and wasting raw materials. Furthermore, manual sampling and testing exposes workers to frequent ammonia gas, increasing safety risks. Utility Model Content

[0003] The technical problem to be solved by this utility model is to overcome the defects of the prior art and provide a hexamethylenetetramine production device that can accurately determine the reaction endpoint, avoid the delay in determining the reaction endpoint, and thus stop the supply of ammonia in time to avoid excessive ammonia supply and waste. It can also prevent workers from coming into contact with ammonia to reduce safety risks and improve operational safety.

[0004] To solve the above-mentioned technical problems, the technical solution of this utility model is: a hexamethylenetetramine production device, including a reaction vessel, a vaporizer, a filter, a circulating pump, a heat exchanger, a formaldehyde feed pipeline, an ammonia source feed pipeline, a first control valve, a second control valve, a near-infrared online analyzer, and a controller;

[0005] The formaldehyde feed pipeline is connected to the reaction vessel, and the first control valve is connected to the formaldehyde feed pipeline;

[0006] The ammonia source feed pipeline is connected to the feed port of the vaporizer, the discharge port of the vaporizer is connected to the inlet of the filter, the outlet of the filter is connected to the reactor, and the second control valve is connected in the ammonia source feed pipeline;

[0007] The inlet of the circulating pump is connected to the reactor, the outlet of the circulating pump is connected to the inlet of the vaporizer, the outlet of the vaporizer is connected to the inlet of the heat exchanger, and the outlet of the heat exchanger is connected to the reactor.

[0008] The probe of the near-infrared online analyzer is installed on the outlet pipeline of the circulating pump. The near-infrared online analyzer is used to monitor the concentration changes of formaldehyde, ammonia and hexamethylenetetramine in the liquid in the reaction vessel in real time when the circulating pump pumps the liquid in the reaction vessel.

[0009] The controller is connected to the near-infrared online analyzer and the second control valve respectively, and is used to control the second control valve to close based on the concentration changes of formaldehyde, ammonia and hexamethylenetetramine monitored by the near-infrared online analyzer.

[0010] Further, a specific structure of the ammonia source feed pipeline is provided, wherein the ammonia source feed pipeline includes a gaseous ammonia branch, a liquid ammonia branch, and a main pipeline;

[0011] The gaseous ammonia branch and the liquid ammonia branch are respectively connected to one end of the main pipeline, and the other end of the main pipeline is connected to the feed inlet of the vaporizer;

[0012] A first switching valve is connected to the gaseous ammonia branch, a second switching valve is connected to the liquid ammonia branch, and the second control valve is connected to the main pipeline.

[0013] Furthermore, flow meters are connected to the gaseous ammonia branch, the liquid ammonia branch, and the formaldehyde feed line, respectively.

[0014] Furthermore, the hexamethylenetetramine production apparatus also includes an intermediate storage tank, transfer pipelines, transfer valves, and circulation valves;

[0015] One end of the transfer pipeline is connected to the outlet of the circulating pump, and the other end of the transfer pipeline is connected to the intermediate storage tank. The transfer valve is connected in the transfer pipeline, and the circulating valve is connected to the inlet of the vaporizer.

[0016] Furthermore, the hexamethylenetetramine production apparatus may also include a transfer pump and a membrane evaporator, wherein the inlet of the transfer pump is connected to the intermediate storage tank, and the outlet of the transfer pump is connected to the material inlet of the membrane evaporator.

[0017] Furthermore, the outlet of the delivery pump is connected to the material inlet of the membrane evaporator via a feed pipeline, and the feed pipeline is equipped with a switch valve and a flow meter.

[0018] Furthermore, the hexamethylenetetramine production apparatus also includes a concentrate intermediate tank, and the material outlet of the membrane evaporator is connected to the concentrate intermediate tank.

[0019] Furthermore, the hexamethylenetetramine production apparatus also includes a discharge pump and a finished product storage tank. The inlet of the discharge pump is connected to the intermediate tank of the concentrate, and the outlet of the discharge pump is connected to the finished product storage tank.

[0020] Furthermore, the intermediate tank of the concentrate is connected to a nitrogen inlet pipe and a tail gas outlet pipe, and valves are connected to the nitrogen inlet pipe and the tail gas outlet pipe respectively.

[0021] Furthermore, level gauges are connected to the intermediate tank of the concentrate and the reaction vessel, respectively.

[0022] The above technical solution involves first opening the first control valve to inject formaldehyde solution into the reactor through the formaldehyde feed pipe. Once the formaldehyde solution reaches a certain level, the first control valve is closed. Then, the second control valve is opened and the circulation pump is started. The liquid in the reactor, pumped by the circulation pump, flows sequentially through the vaporizer and heat exchanger before returning to the reactor. At least one of ammonia gas and liquid ammonia is introduced from the ammonia source feed pipe, flows sequentially through the vaporizer and filter, and then flows into the reactor. Specifically, when the liquid in the reactor flows through the vaporizer, it exchanges heat with the liquid ammonia flowing through it, causing the liquid ammonia to vaporize into ammonia gas. The ammonia gas then flows through the filter and into the reactor to react with the formaldehyde solution to generate hexamethylenetetramine. Furthermore, the inlet of the heat exchanger is used to connect cooling water, and the outlet is used to discharge cooling water. When the liquid in the reactor flows through the heat exchanger, it exchanges heat with the cooling water, cools down, and then flows back to the reactor, thereby removing the heat of reaction and maintaining a constant reaction temperature in the reactor. Furthermore, the specific structure and working principle of the near-infrared online analyzer are existing technologies. During the reaction of ammonia and formaldehyde solution in the reactor to produce hexamethylenetetramine, the circulating pump continuously pumps the reaction liquid in the reactor for circulation. The probe of the near-infrared online analyzer can contact the reaction liquid in the outlet pipeline of the circulating pump through a probe window made of corrosion-resistant material. The near-infrared online analyzer monitors the concentration changes of formaldehyde, ammonia, and hexamethylenetetramine in the reaction liquid by acquiring near-infrared spectral data of the reaction liquid in real time. Then, the controller can accurately determine the reaction endpoint based on the monitored concentration changes of formaldehyde, ammonia, and hexamethylenetetramine. Consequently, the controller can promptly control the second control valve to close at the end of the reaction to stop the supply of ammonia, thereby terminating the reaction in the reactor. This avoids excessive ammonia supply due to delayed determination of the reaction endpoint, thus preventing waste of ammonia raw materials. In addition, it can also avoid frequent contact with ammonia by workers, reduce reaction runaway or secondary pollution caused by human error, improve safety, and reduce safety risks. Attached Figure Description

[0023] Figure 1 A process flow diagram of a part of the hexamethylenetetramine production apparatus of this utility model;

[0024] Figure 2 This is a process flow diagram of another part of the hexamethylenetetramine production apparatus of this utility model;

[0025] In the diagram: 1. Reactor; 2. Vaporizer; 3. Filter; 4. Circulation pump; 5. Heat exchanger; 6. Formaldehyde feed line; 7. First control valve; 8. Second control valve; 9. Gaseous ammonia branch; 10. Liquid ammonia branch; 11. Main line; 12. First switching valve; 13. Second switching valve; 14. Intermediate storage tank; 15. Transfer line; 16. Transfer valve; 17. Circulation valve; 18. Transfer pump; 19. Membrane evaporator; 20. Feed line; 21. Transfer line; 22. Concentrate intermediate tank; 23. Steam line; 24. Condensate main line; 25. Discharge pump; 26. Finished product storage tank; 27. Nitrogen inlet line; 28. Tail gas discharge line. Detailed Implementation

[0026] To make the contents of this utility model easier to understand, the present utility model will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0027] like Figure 1 As shown, a hexamethylenetetramine production apparatus includes a reaction vessel 1, a vaporizer 2, a filter 3, a circulating pump 4, a heat exchanger 5, a formaldehyde feed pipeline 6, an ammonia source feed pipeline, a first control valve 7, a second control valve 8, a near-infrared online analyzer, and a controller.

[0028] The formaldehyde feed line 6 is connected to the reactor 1, and the first control valve 7 is connected to the formaldehyde feed line 6.

[0029] The ammonia source feed pipeline is connected to the feed port of the vaporizer 2, the discharge port of the vaporizer 2 is connected to the inlet of the filter 3, the outlet of the filter 3 is connected to the reactor 1, and the second control valve 8 is connected in the ammonia source feed pipeline.

[0030] The inlet of the circulating pump 4 is connected to the reactor 1, the outlet of the circulating pump 4 is connected to the inlet of the vaporizer 2, the outlet of the vaporizer 2 is connected to the inlet of the heat exchanger 5, and the outlet of the heat exchanger 5 is connected to the reactor 1.

[0031] The probe of the near-infrared online analyzer is installed on the outlet pipeline of the circulating pump 4. The near-infrared online analyzer is used to monitor the concentration changes of formaldehyde, ammonia and hexamethylenetetramine in the liquid in the reaction vessel 1 in real time when the circulating pump 4 pumps the liquid in the reaction vessel 1.

[0032] The controller is connected to the near-infrared online analyzer and the second control valve 8 respectively, and is used to control the second control valve 8 to close based on the concentration changes of formaldehyde, ammonia and hexamethylenetetramine monitored by the near-infrared online analyzer.

[0033] Specifically, firstly, the first control valve 7 is opened to inject formaldehyde solution into the reactor 1 from the formaldehyde feed pipe 6. Once the formaldehyde solution reaches a certain level, the first control valve 7 is closed. Then, the second control valve 8 is opened and the circulation pump 4 is started. The liquid in the reactor 1 flows sequentially through the vaporizer 2 and the heat exchanger 5 under the pumping of the circulation pump 4, and then flows back into the reactor 1. At least one of ammonia gas and liquid ammonia is introduced from the ammonia source feed pipe, flows sequentially through the vaporizer 2 and the filter 3, and then flows into the reactor 1. When the liquid in the reactor 1 flows through the vaporizer 2, it exchanges heat with the liquid ammonia flowing through the vaporizer 2, causing the liquid ammonia to vaporize into ammonia gas. The ammonia gas then flows through the filter 3 and into the reactor 1 to react with the formaldehyde solution to produce hexamethylenetetramine. Furthermore, the inlet of the heat exchanger 5 is used to connect cooling water, and the outlet of the heat exchanger 5 is used to discharge cooling water. When the liquid in the reactor 1 flows through the heat exchanger 5, it will exchange heat with the cooling water, cool down, and then flow back into the reactor 1, thereby removing the heat of reaction to maintain a constant reaction temperature in the reactor 1. More specifically, the structure and working principle of the near-infrared online analyzer are existing technologies. During the reaction of ammonia and formaldehyde solution in reactor 1 to produce hexamethylenetetramine, the circulating pump 4 continuously pumps the reaction liquid in reactor 1 for circulation. The probe of the near-infrared online analyzer can contact the reaction liquid in the outlet pipeline of the circulating pump 4 through the probe window made of corrosion-resistant material. The near-infrared online analyzer monitors the concentration changes of formaldehyde, ammonia, and hexamethylenetetramine in the reaction liquid by collecting near-infrared spectral data of the reaction liquid in real time. Then, the controller can accurately determine the reaction endpoint based on the monitored concentration changes of formaldehyde, ammonia, and hexamethylenetetramine. Consequently, the controller can promptly control the second control valve 8 to close at the end of the reaction to stop the supply of ammonia, thereby terminating the reaction in reactor 1. This avoids excessive ammonia supply due to delayed determination of the reaction endpoint, thus preventing waste of ammonia raw materials. In addition, it can also avoid frequent contact with ammonia by workers, reduce reaction runaway or secondary pollution caused by human error, improve safety, and reduce safety risks.

[0034] In this embodiment, the near-infrared online analyzer monitors and samples every 30 seconds, with a response time of less than 5 seconds. The controller can accurately determine the reaction endpoint through a multivariate regression model, avoiding delays in endpoint determination and ensuring precise tracking of the reaction process. This keeps the ammonia input within ±5% of the theoretical amount, significantly reducing ammonia waste and lowering ammonia raw material costs. The multivariate regression model is existing technology. Both the first control valve 7 and the second control valve 8 can be flow control valves. The filter 3 can be an ammonia filter, and two circulating pumps 4 are connected in parallel.

[0035] like Figure 1As shown, the ammonia source feed pipeline may include a gaseous ammonia branch 9, a liquid ammonia branch 10, and a main pipeline 11;

[0036] The gaseous ammonia branch 9 and the liquid ammonia branch 10 are respectively connected to one end of the main pipeline 11, and the other end of the main pipeline 11 is connected to the feed inlet of the vaporizer 2.

[0037] A first switching valve 12 is connected to the gaseous ammonia branch 9, and a second switching valve 13 is connected to the liquid ammonia branch 10. The second control valve 8 is connected to the main pipeline 11. Specifically, when the first switching valve 12 is opened, gaseous ammonia can be introduced through the gaseous ammonia branch 9, and when the second switching valve 13 is opened, liquid ammonia can be introduced through the liquid ammonia branch 10. This is because the ammonia source can be freely selected as needed, and the liquid ammonia will vaporize into ammonia gas when it flows through the vaporizer 2.

[0038] In this embodiment, flow meters are connected to the gaseous ammonia branch 9, the liquid ammonia branch 10, and the formaldehyde feed line 6, respectively, so as to detect the flow rate of ammonia in the gaseous ammonia branch 9, the flow rate of liquid ammonia in the liquid ammonia branch 10, and the flow rate of formaldehyde solution in the formaldehyde feed line 6.

[0039] like Figure 1 As shown, the hexamethylenetetramine production apparatus may further include an intermediate storage tank 14, a transfer pipeline 15, a transfer valve 16, and a circulation valve 17.

[0040] One end of the transfer pipeline 15 is connected to the outlet of the circulation pump 4, and the other end of the transfer pipeline 15 is connected to the intermediate storage tank 14. The transfer valve 16 is connected in the transfer pipeline 15, and the circulation valve 17 is connected to the inlet of the vaporizer 2. Specifically, when the reaction in the reactor 1 is terminated, the transfer valve 16 needs to be opened and the circulation valve 17 needs to be closed. At this time, the liquid in the reactor 1 will be transferred from the transfer pipeline 15 to the intermediate storage tank 14 for storage under the pumping of the circulation pump 4.

[0041] like Figure 1 , 2 As shown, the hexamethylenetetramine production apparatus may further include a transfer pump 18 and a membrane evaporator 19. The inlet of the transfer pump 18 is connected to the intermediate storage tank 14, and the outlet of the transfer pump 18 is connected to the material inlet of the membrane evaporator 19.

[0042] like Figure 1 , 2 As shown, the outlet of the conveying pump 18 is connected to the material inlet of the membrane evaporator 19 through the feeding pipeline 20. The feeding pipeline 20 is connected to a switch valve and a flow meter. The inlet of the conveying pump 18 is connected to the intermediate storage tank 14 through the conveying pipeline 21. The conveying pipeline 21 is connected to a conveying valve. There are two conveying pumps 18 connected in parallel.

[0043] like Figure 2 As shown, the hexamethylenetetramine production apparatus may further include a concentrated liquid intermediate tank 22. The material outlet of the membrane evaporator 19 is connected to the concentrated liquid intermediate tank 22. The steam inlet of the membrane evaporator 19 is connected to the steam pipeline 23 to receive saturated steam. The condensate outlet of the membrane evaporator 19 is connected to the condensate main pipe 24 to discharge steam and condensate. The specific structure of the membrane evaporator 19 is prior art well known to those skilled in the art, and will not be described in detail in this embodiment.

[0044] like Figure 2 As shown, the hexamethylenetetramine production apparatus may further include a discharge pump 25 and a finished product storage tank 26. The inlet of the discharge pump 25 is connected to the intermediate concentrate tank 22, and the outlet of the discharge pump 25 is connected to the finished product storage tank 26. Specifically, the liquid in the intermediate storage tank 14 can be pumped from the feed pipeline 20 to the membrane evaporator 19 for concentration by the transfer pump 18. The concentrated liquid will flow from the material outlet of the membrane evaporator 19 into the intermediate concentrate tank 22, and then the discharge pump 25 will pump the concentrated liquid in the intermediate concentrate tank 22 to the finished product storage tank 26.

[0045] like Figure 2 As shown, the intermediate tank 22 of the concentrate is connected to a nitrogen inlet pipe 27 and a tail gas outlet pipe 28, and valves are connected to the nitrogen inlet pipe 27 and the tail gas outlet pipe 28 respectively. Specifically, opening the valve in the nitrogen inlet pipe 27 allows nitrogen to be injected into the intermediate tank 22 to create an inert environment, and opening the valve in the tail gas outlet pipe 28 allows the tail gas in the intermediate tank 22 to be discharged. In this embodiment, level gauges are connected to the intermediate tank 22 of the concentrate and the reaction vessel 1 respectively.

[0046] In this embodiment, the reaction process in the reactor 1 can be monitored in real time by a near-infrared online analyzer. The controller can control the operation of the circulating pump 4, the delivery pump 18, the discharge pump 25, the first control valve 7, the second control valve 8, the first switching valve 12, the second switching valve 13, the transfer valve 16, the circulating valve 17, and the switching valve, thereby achieving automatic control. The controller can be a PLC controller.

[0047] In summary, the first control valve 7 is opened to allow formaldehyde solution to be injected into the reactor 1 from the formaldehyde feed pipe 6. Once the formaldehyde solution reaches a certain level, the first control valve 7 is closed. Then, the second control valve 8 is opened and the circulation pump 4 is started. The liquid in the reactor 1, pumped by the circulation pump 4, flows sequentially through the vaporizer 2 and the heat exchanger 5, and then returns to the reactor 1. At least one of ammonia gas and liquid ammonia is introduced from the ammonia source feed pipe, flows sequentially through the vaporizer 2 and the filter 3, and then flows into the reactor 1. When the liquid in the reactor 1 flows through the vaporizer 2, it exchanges heat with the liquid ammonia flowing through the vaporizer 2, causing the liquid ammonia to vaporize into ammonia gas. The ammonia gas then flows through the filter 3 and into the reactor 1 to react with the formaldehyde solution to produce hexamethylenetetramine. Furthermore, the inlet of the heat exchanger 5 is used to connect cooling water, and the outlet of the heat exchanger 5 is used to discharge cooling water. When the liquid in the reactor 1 flows through the heat exchanger 5, it will exchange heat with the cooling water, cool down, and then flow back into the reactor 1, thereby removing the heat of reaction to maintain a constant reaction temperature in the reactor 1. Furthermore, the specific structure and working principle of the near-infrared online analyzer are existing technologies. During the reaction of ammonia and formaldehyde solution in reactor 1 to generate hexamethylenetetramine, the circulating pump 4 continuously pumps the reaction liquid in reactor 1 for circulation. The probe of the near-infrared online analyzer can contact the reaction liquid in the outlet pipeline of the circulating pump 4 through the probe window made of corrosion-resistant material. The near-infrared online analyzer monitors the concentration changes of formaldehyde, ammonia, and hexamethylenetetramine in the reaction liquid by collecting near-infrared spectral data of the reaction liquid in real time. Then, the controller can accurately determine the reaction endpoint based on the monitored concentration changes of formaldehyde, ammonia, and hexamethylenetetramine. Consequently, the controller can promptly control the second control valve 8 to close at the end of the reaction to stop the supply of ammonia, thereby terminating the reaction in reactor 1. This avoids excessive ammonia supply due to delayed determination of the reaction endpoint, thus preventing waste of ammonia raw materials. In addition, it can also avoid frequent contact with ammonia by workers, reduce reaction runaway or secondary pollution caused by human error, improve safety, and reduce safety risks.

[0048] The specific embodiments described above further illustrate the technical problems, technical solutions, and beneficial effects of this utility model. It should be understood that the above descriptions are merely specific embodiments of this utility model and are not intended to limit this utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A hexamethylenetetramine production apparatus, characterized in that, Includes a reaction vessel (1), a vaporizer (2), a filter (3), a circulating pump (4), a heat exchanger (5), a formaldehyde feed pipeline (6), an ammonia source feed pipeline, a first control valve (7), a second control valve (8), a near-infrared online analyzer, and a controller; The formaldehyde feed line (6) is connected to the reactor (1), and the first control valve (7) is connected in the formaldehyde feed line (6); The ammonia source feed pipeline is connected to the feed port of the vaporizer (2), the discharge port of the vaporizer (2) is connected to the inlet of the filter (3), the outlet of the filter (3) is connected to the reactor (1), and the second control valve (8) is connected in the ammonia source feed pipeline. The inlet of the circulating pump (4) is connected to the reactor (1), the outlet of the circulating pump (4) is connected to the inlet of the vaporizer (2), the outlet of the vaporizer (2) is connected to the inlet of the heat exchanger (5), and the outlet of the heat exchanger (5) is connected to the reactor (1). The probe of the near-infrared online analyzer is installed on the outlet pipeline of the circulating pump (4). The near-infrared online analyzer is used to monitor the concentration changes of formaldehyde, ammonia and hexamethylenetetramine in the liquid in the reaction vessel (1) in real time when the circulating pump (4) pumps the liquid in the reaction vessel (1). The controller is connected to the near-infrared online analyzer and the second control valve (8) respectively, and is used to control the second control valve (8) to close according to the concentration change information of formaldehyde, ammonia and hexamethylenetetramine monitored by the near-infrared online analyzer.

2. The hexamethylenetetramine production apparatus according to claim 1, characterized in that, The ammonia source feed pipeline includes a gaseous ammonia branch (9), a liquid ammonia branch (10), and a main pipeline (11). The gaseous ammonia branch (9) and the liquid ammonia branch (10) are respectively connected to one end of the main pipeline (11), and the other end of the main pipeline (11) is connected to the feed inlet of the vaporizer (2). The gaseous ammonia branch (9) is connected to a first switching valve (12), the liquid ammonia branch (10) is connected to a second switching valve (13), and the second control valve (8) is connected to the main pipeline (11).

3. The hexamethylenetetramine production apparatus according to claim 2, characterized in that, Flow meters are connected to the gaseous ammonia branch (9), the liquid ammonia branch (10), and the formaldehyde feed line (6), respectively.

4. The hexamethylenetetramine production apparatus according to claim 1, characterized in that, It also includes an intermediate storage tank (14), a transfer pipeline (15), a transfer valve (16), and a circulation valve (17). One end of the transfer pipeline (15) is connected to the outlet of the circulating pump (4), the other end of the transfer pipeline (15) is connected to the intermediate storage tank (14), the transfer valve (16) is connected in the transfer pipeline (15), and the circulating valve (17) is connected to the inlet of the vaporizer (2).

5. The hexamethylenetetramine production apparatus according to claim 4, characterized in that, It also includes a transfer pump (18) and a membrane evaporator (19), the inlet of which is connected to the intermediate storage tank (14), and the outlet of which is connected to the material inlet of the membrane evaporator (19).

6. The hexamethylenetetramine production apparatus according to claim 5, characterized in that, The outlet of the delivery pump (18) is connected to the material inlet of the membrane evaporator (19) through the feed pipeline (20), and the feed pipeline (20) is equipped with a switch valve and a flow meter.

7. The hexamethylenetetramine production apparatus according to claim 5, characterized in that, It also includes a concentrate intermediate tank (22), and the material outlet of the membrane evaporator (19) is connected to the concentrate intermediate tank (22).

8. The hexamethylenetetramine production apparatus according to claim 7, characterized in that, It also includes a discharge pump (25) and a finished product storage tank (26), the inlet of which is connected to the intermediate tank (22) of the concentrate, and the outlet of which is connected to the finished product storage tank (26).

9. The hexamethylenetetramine production apparatus according to claim 7, characterized in that, The intermediate tank (22) of the concentrate is connected to a nitrogen inlet pipe (27) and a tail gas outlet pipe (28), and valves are connected to the nitrogen inlet pipe (27) and the tail gas outlet pipe (28).

10. The hexamethylenetetramine production apparatus according to claim 7, characterized in that, The intermediate tank (22) of the concentrate and the reactor (1) are respectively connected to level gauges.

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