A reactor for producing dimethylethanolamine and its production method

Abstract

The present invention relates to a reactor for the production of dimethylethanolamine and its production method, belonging to the field of chemical production equipment, including a tank body, a tank cover, catalyst tubes, a piston sleeve, a contact rod and a contact head. The tank cover is erected on the top of the tank body, and gaseous ethylene oxide and liquid dimethylamine flowing are introduced into the tank body. A number of catalyst tubes filled with granular catalysts are fixedly connected inside the tank body. A flexible piston sleeve is fixedly connected to the bottom of the tank cover. Colored water and pressurized nitrogen are filled between the piston sleeve and the tank cover. The contact rod is erected on the top of the piston sleeve, and two contact heads are fixedly connected to the top of the tank cover at intervals. The piston sleeve rises to make the contact rod contact the contact heads and make an electric signal connected between the contact heads. The present invention has the advantages of effectively inhibiting the reaction of ethylene oxide with water and improving the product yield.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical production equipment, and particularly relates to a reaction kettle for producing dimethylethanolamine and a production method thereof. Background Art

[0002] N,N-dimethylethanolamine (DMEA) is a colorless or light yellow liquid with an ammonia smell. It can be miscible with acetone, ether, and benzene, and can also dissolve in water. It is an amphoteric compound that is both hydrophilic and lipophilic, and has been widely used due to its excellent structure and outstanding performance.

[0003] Currently, the main methods for synthesizing DMEA are the following four:

[0004] ① Ethylene oxide is introduced into the ethanol solution of dimethylamine. After the absorption is completed, the finished product is separated and collected. This route has a high reaction temperature, large material loss, is not easy to control, and is dangerous.

[0005] ② Chloroethanol is added dropwise to the dimethylamine solution. After addition, the reaction is carried out at 100 °C for 8 h, and then neutralized, layered, extracted, and fractionated to obtain the finished product. This route has a long reaction time, high energy consumption, and a complex process.

[0006] ③ The dimethylamine solution and ethylene glycol are mixed and reacted, and a catalyst is added. This route has a high reaction temperature, a large amount of catalyst used, and a high reaction cost.

[0007] ④ Dimethylamine and ethylene oxide steam are introduced into a tubular reactor and reacted under high temperature and high pressure. Although this route has a high yield, the process is complex, the technical requirements are strict, and it is not easy to control the reaction.

[0008] Therefore, in view of the above deficiencies, a reaction kettle for producing dimethylethanolamine is needed. Summary of the Invention

[0009] (1) Technical Problems to be Solved

[0010] The technical problem to be solved by the present invention is to solve the problems of large investment in traditional production equipment, a large number of equipment, uneven distribution of catalysts, uneven intake distribution, large amount of inhibitor used, and low level of automatic control.

[0011] (2) Technical Solutions

[0012] To solve the above technical problems, the present invention provides a reactor for producing dimethylethanolamine, which includes a tank body, a tank cover, catalyst tubes, a piston sleeve, a contact rod and a contact head. The tank cover is mounted on the top of the tank body, and gaseous ethylene oxide and liquid dimethylamine flow through the tank body. A number of catalyst tubes filled with granular catalysts are fixedly connected inside the tank body. A flexible piston sleeve is fixedly connected to the bottom of the tank cover. Colored water and pressurized nitrogen are filled between the piston sleeve and the tank cover. The contact rod is mounted on the top of the piston sleeve, and two contact heads are fixedly connected to the top of the tank cover at intervals. The piston sleeve rises to make the contact rod contact the contact heads and connect an electric signal between the contact heads.

[0013] As a further description of the present invention, preferably, the piston sleeve is made of a multi-layer nylon-coated PCV fabric, and the spreading area of the piston sleeve is larger than the outer diameter of the tank cover.

[0014] As a further description of the present invention, preferably, a ring-shaped top ring is fixedly connected to the middle of the top end of the piston sleeve, and a through hole is opened at the bottom end of the top ring; a metal guide ring is inserted into the top of the top ring, and two contact rods are threadedly connected to the guide ring.

[0015] As a further description of the present invention, preferably, the contact rod is composed of multiple metal segments, and a threaded rod is fixedly connected to the bottom of each segment, and the threaded rod is threadedly connected to the top of the adjacent segment.

[0016] As a further description of the present invention, preferably, the total amount of water filled between the piston sleeve and the tank cover is less than the minimum volume between the piston sleeve and the tank cover.

[0017] As a further description of the present invention, preferably, large-particle-size catalyst particles are filled at the bottom of the catalyst tube, and small-particle-size catalyst particles are filled at the top, and the upper and lower ends of the catalyst tube are blocked by a grid.

[0018] As a further description of the present invention, preferably, a number of baffle plates are fixedly connected to the tank body at intervals along the axial direction, and the catalyst tubes penetrate through the baffle plates; the baffle plates are all provided with channels, and the channels on adjacent baffle plates are not on the same vertical line.

[0019] As a further description of the present invention, preferably, a temperature-controlled circulating liquid inlet is provided on one side of the top of the tank body to introduce a liquid for heating the liquid phase into the tank body, and a temperature-controlled circulating liquid outlet is provided on the other side of the bottom of the tank body to circulate the liquid in the tank body.

[0020] As a further description of the present invention, preferably, a feed and liquid phase circulation upper pipe is provided on one side of the top of the tank body, and a feed and circulation lower pipe is provided on one side of the bottom of the tank body. The feed and liquid phase circulation upper pipe and the feed and circulation lower pipe are connected by an external transparent pipe.

[0021] The present invention also provides a production method for a reactor for producing dimethylethanolamine, which includes the following steps:

[0022] Ⅰ. Fill the catalyst into the catalyst tubes, inject water into the tank cover to make the piston sleeve sink downward, and at the same time, charge nitrogen into the tank cover for pressurization;

[0023] Ⅱ. Inject liquid dimethylamine into the tank body, and make the dimethylamine circulate in the tank body through the feed and liquid-phase circulation upper pipe and the feed and circulation lower pipe by means of a pump;

[0024] Ⅲ. Pass the circulating liquid into the tank body through the temperature-controlled circulating liquid inlet to raise the temperature of the liquid phase. After the temperature in the tank body reaches the set temperature, inject ethylene oxide into the tank body. After the ethylene oxide is evenly distributed in the tank body through the gas distributor arranged at the bottom of the tank body, it is fully mixed with the liquid-phase dimethylamine;

[0025] Ⅳ. When the feed pressure of ethylene oxide is greater than the nitrogen seal pressure in the tank cover, the piston sleeve rises to make the contact rod contact the contact head. After the two contact heads are connected, the electrical signal in the controller is connected, and then the controller controls to stop injecting ethylene oxide into the tank body;

[0026] Ⅴ. As the reaction proceeds, ethylene oxide is consumed and the pressure in the tank body drops. Under the action of the gravity of water, the contact rod and the contact head are separated, so that the controller controls to inject ethylene oxide into the tank body again, realizing the repeated gas-phase feed circulation;

[0027] Ⅵ. When the total feed amount of ethylene oxide reaches the set value, continue the liquid-phase circulation; finally, flash distill the product to complete the production of dimethylethanolamine; if the piston sleeve is damaged or the interface sealing performance deteriorates, water flows into the tank body and into the transparent pipe between the feed and liquid-phase circulation upper pipe and the feed and circulation lower pipe, and is observed by the staff and the equipment is shut down.

[0028] (III) Advantageous Effects

[0029] The above technical solutions of the present invention have the following advantages:

[0030] The present invention combines the advantages of a tubular reactor and a shell-and-tube reactor, uses a catalyst to enhance the selectivity of the reaction, reduces the reaction temperature and pressure, effectively inhibits the hydration reaction of ethylene oxide, and improves the reaction yield; in addition, a gas distributor is used to charge ethylene oxide into the tower, and a pump circulation is used to increase the contact frequency between the reactants and the catalyst, inhibit the polymerization reaction of the reactants, reduce the dosage of chemical polymerization inhibitors at the same time, and reduce the energy consumption of subsequent purification; moreover, a flexible piston sleeve is used, which is suitable for charging reactions in different batches, facilitates the control of the reaction time, and improves the reaction yield; at the same time, remote temperature and liquid level transmission devices are provided, which are connected to the PLC distributed control system in the main control room, and control signals are sent to devices such as an automatic flowmeter and an electromagnetic control valve according to the transmitted data to achieve remote automatic control. Description of the Drawings

[0031] Figure 1It is the overall assembly effect diagram of the present invention;

[0032] Figure 2 It is the sectional view of the present invention;

[0033] Figure 3 It is Figure 2 the enlarged view of A in

[0034] Figure 4 the partial sectional view of the tank cover of the present invention.

[0035] In the figure: 1. Tank body; 11. Ethylene oxide feed pipe; 12. Upper pipe for feed and liquid phase circulation; 13. Inlet for temperature-controlled circulating liquid; 14. Outlet for temperature-controlled circulating liquid; 15. Feed main pipe; 16. Lower pipe for feed and circulation; 17. Installation pipe for liquid level gauge; 18. Interface for remote transmitter; 19. Leg; 2. Tank cover; 21. Nitrogen seal; 22. Water seal; 23. Observation port; 24. Liquid level gauge; 25. Inverted groove; 3. Catalyst tube bundle; 31. Baffle; 32. Liquid phase circulation distributor; 4. Piston sleeve; 41. Top ring; 42. Water; 43. Hoop ring; 5. Contact rod; 51. Threaded rod; 52. Guide ring; 6. Contact head. Specific embodiments

[0036] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0037] A reactor for producing dimethylethanolamine, in combination with Figure 1 、 Figure 2 includes a tank body 1, a tank cover 2, a catalyst tube bundle 3, a piston sleeve 4, a contact rod 5 and a contact head 6. The tank cover 2 is erected on the top of the tank body 1. Gaseous ethylene oxide and liquid dimethylamine flow through the tank body 1. A number of catalyst tubes 3 filled with granular catalysts are fixedly connected inside the tank body 1. A flexible piston sleeve 4 is fixedly connected to the bottom of the tank cover 2. Colored water and pressurized nitrogen are filled between the piston sleeve 4 and the tank cover 2. The contact rod 5 is erected on the top of the piston sleeve 4. Two contact heads 6 are fixedly connected to the top of the tank cover 2 at intervals. The piston sleeve 4 rises to make the contact rod 5 contact the contact heads 6 and make an electrical signal connected between the contact heads 6.

[0038] In combination with Figure 1 、 Figure 2, the tank body 1 is a cylindrical structure with an open upper part, and the outer part of the tank body 1 is fixedly connected with support legs 19 to lift the tank body 1 off the ground. One side of the bottom of the tank body 1 is fixedly connected with an ethylene oxide feed pipe 11, and an ethylene oxide feed compressor is connected to the ethylene oxide feed pipe 11. Through the compression of the ethylene oxide feed compressor, gaseous ethylene oxide can enter the bottom of the tank body 1 through a pipeline. A gas distributor is provided at the bottom of the tank body 1. The gas distributor is horizontally distributed in the tank body 1 and can evenly distribute the gaseous ethylene oxide, so that the gaseous ethylene oxide can be evenly distributed during the process of flowing upward from the bottom of the tank body 1.

[0039] Combined with Figure 1 , Figure 2 , one side of the top of the tank body 1 is provided with a feed and liquid phase circulation upper pipe 12, and one side of the bottom of the tank body 1 is provided with a feed and circulation lower pipe 16 with a valve. The feed and liquid phase circulation upper pipe 12 and the feed and circulation lower pipe 16 are connected by an external transparent pipe. A number of valves and a diaphragm pump are connected to the connected pipelines. At the same time, a discharge pipe is connected to one side of the pipeline to export the material (not shown in the figure). A feed main pipe 15 with a valve is also fixedly connected to the bottom of the tank body 1. The feed main pipe 15 is communicated with the feed and circulation lower pipe 16. A main pipeline with a valve is connected between the connection of the feed main pipe 15 and the feed and circulation lower pipe 16 and the tank body 1. When the valve on the main pipeline is closed, the liquid dimethylamine solution can be pumped into the feed main pipe 15 - the feed and circulation lower pipe 16 - the feed and liquid phase circulation upper pipe 12 and enter the top of the tank body 1 through the diaphragm pump, so that the liquid dimethylamine solution flows downward and the gaseous ethylene oxide flows upward, playing a role of automatic mixing.

[0040] Combined with Figure 1 , Figure 2 , a number of baffle plates 31 are fixedly connected to the tank body 1 at intervals along the axial direction. The catalyst tubes 3 pass through the baffle plates 31 to play a role in fixing the catalyst tubes 3. The baffle plates 31 are all provided with channels, and the channels on adjacent baffle plates 31 are not on the same vertical line, so that the gaseous ethylene oxide flows in a serpentine shape when flowing upward, and thus is fully mixed with the liquid dimethylamine. In addition, a liquid phase circulation distributor 32 is provided at the outlet end of the feed and liquid phase circulation upper pipe 12 of the tank body 1 to make the flowing out liquid flow horizontally along the tank body 1, playing a role of evenly distributing the liquid.

[0041] Combined with Figure 1 , Figure 2, on one side of the top of the tank body 1, there is a temperature-controlled circulating liquid inlet 13 for introducing a liquid that raises the temperature of the liquid phase into the tank body 1. The temperature-controlled circulating liquid inlet 13 is located above the highest baffle plate 31. On the other side of the bottom of the tank body 1, there is a temperature-controlled circulating liquid outlet 14, and the temperature-controlled circulating liquid outlet 14 is located below the lowest baffle plate 31. The temperature-controlled circulating liquid flows into the tank body 1 from the top and flows downward in a serpentine shape along the baffle plate 31, and then flows out from the temperature-controlled circulating liquid outlet 14, so that the liquid circulates in the tank body 1. The temperature of ethylene oxide is relatively low, and the temperature control system automatically increases the flow rate of the temperature-controlled circulating liquid inlet 13, thereby keeping the temperature in the reaction kettle constant. At the same time, under the action of the baffle plate 31, it is ensured that sufficient contact with the liquid can be achieved, and further, it can be ensured that the reaction liquid is heated evenly.

[0042] Combined with Figure 1 , Figure 2 , the tank body 1 is provided with liquid level gauge installation pipes 17 and remote measurement interface 18 at multiple locations. A liquid level gauge is installed on the liquid level gauge installation pipe 17, and a thermometer with a remote transmission function is installed on the remote measurement interface 18. By installing the liquid level gauge, the liquid volume in the tank body 1 can be measured. When the liquid volume increases or decreases, the control system correspondingly controls the amount of liquid flowing in. By setting the thermometer to measure the temperature in the tank body 1, and then according to the need, the control system controls the inflow amount of the temperature-controlled circulating liquid to ensure a constant temperature in the tank body 1.

[0043] Combined with Figure 1 , Figure 2 , the tank cover 2 is a hemispherical shell. On one side of the top of the tank cover 2, there is a nitrogen seal 21 for injecting pressurized nitrogen between the tank cover 2 and the piston sleeve 4. On one side of the top of the tank cover 2, there is a water seal 22 for injecting colored water 42 between the tank cover 2 and the piston sleeve 4. The total amount of water 42 filled between the piston sleeve 4 and the tank cover 2 is less than the minimum volume between the piston sleeve 4 and the tank cover 2. On the top of the tank cover 2, there is also an observation port 23 for observation and maintenance. A liquid level gauge 24 is also provided on the tank cover 2 to prevent the injected water 42 from being excessive and squeezing the water 42 out of the tank cover 2 when the piston sleeve 4 moves upward. In addition, a reverse groove 25 is provided at the interface between the tank cover 2 and the tank body 1 to prevent the right-angle end of the tank cover 2 from scratching the piston sleeve 4.

[0044] Combined with Figure 1 , Figure 2 , the top and bottom of the catalyst tubes 3 with a mesh tube wall are sealed by tube sheets, and a shell cavity is formed in the middle. The catalyst tubes 3 are connected to the temperature-controlled circulating liquid inlet 13 at the top and the temperature-controlled circulating liquid outlet 14 at the bottom. Small particle catalyst particles are filled in the catalyst tubes 3, and both ends are blocked by meshes, and the reaction gas and liquid pass through the middle; large particle size catalyst particles are filled at the bottom of the tubes.

[0045] Combined with Figure 2 , Figure 4, the piston sleeve 4 is made of a multi-layer nylon-coated PCV fabric. The laid-out area of the piston sleeve 4 is larger than the outer diameter of the tank lid 2, enabling the piston sleeve 4 to extend into the tank body 1 or the tank lid 2. The end of the piston sleeve 4 is in a U-shaped structure and its outer end face contacts the tank lid 2. A multi-layered ring-shaped hoop 43 is fixedly connected to the contact surface. Using the hoop 43 can not only fix the piston sleeve 4 on the tank lid 2 but also play a sealing role to prevent water 42 from flowing into the tank body 1. In the middle of the top of the piston sleeve 4, a ring-shaped top ring 41 is fixedly connected. A through hole is provided at the bottom end of the top ring 41, allowing the water 42 inside the top ring 41 to flow to both sides of the piston sleeve 4 when the piston sleeve 4 moves upward. A metal guide ring 52 is inserted into the top of the top ring 4. Two contact rods 5 are threadedly connected to the guide ring 52 to connect the two contact rods 5.

[0046] Combined with Figure 3 、 Figure 4 , the contact rod 5 is composed of multiple metal segments. A threaded rod 51 is fixedly connected to the bottom of each segment, and the threaded rod 51 is threadedly connected to the top of the adjacent segment. According to the elasticity and extensibility of the piston sleeve 4 used, threaded rods 51 of different lengths are selected, eliminating the need to produce new contact rods 5 correspondingly, reducing production costs. The contact area of the contact head 6 inside the tank lid 2 is larger than that of the contact rod 5 to reduce the contact error between the contact rod 5 and the contact head 6 and avoid the problem that the contact rod 5 cannot contact the contact head 6 when it is laterally misaligned by a certain distance.

[0047] The present invention also provides a production method for a reactor used in the production of dimethylethanolamine, including the following steps:

[0048] Ⅰ. Fill the catalyst into the catalyst tube bundle 3, inject water 42 into the tank lid 2 to make the piston sleeve 4 sink downward, and at the same time, fill nitrogen into the tank lid 2 for pressurization. The nitrogen pressure is the same as the pressure required for the reaction. By adding water 42 first, under the action of the gravity of water 42 and the restriction of the top ring 41, the middle part of the piston sleeve 4 naturally sinks. Compared with directly filling high-pressure nitrogen, it will cause the piston sleeve 4 to deform and sink randomly, and there is a certain probability that the contact rod 5 will deflect and collide with the hoop 41 or even the piston sleeve 4, resulting in damage. The above problems can be avoided by adding water 42 first.

[0049] Ⅱ. Inject liquid dimethylamine into the tank body 1, and make the dimethylamine circulate in the tank body 1 through the feed and liquid-phase circulation upper pipe 12 and the feed and circulation lower pipe 16 by means of a diaphragm pump.

[0050] Ⅲ. Pass the circulating liquid into the tank body 1 through the temperature-controlled circulating liquid inlet 13 to raise the temperature of the liquid phase. After the temperature in the tank body 1 reaches the set temperature, inject ethylene oxide into the tank body 1. The ethylene oxide is evenly distributed in the tank body 1 through the gas distributor provided at the bottom of the tank body 1 and is fully mixed with the liquid-phase dimethylamine.

[0051] Ⅳ. When the feed pressure of ethylene oxide is greater than the nitrogen seal pressure inside the tank cover 2, the piston sleeve 4 rises to make the contact rod 5 contact the contact 6. After the two contacts 6 are connected, the electrical signal inside the controller is connected, and then the controller controls to stop injecting ethylene oxide into the tank body 1.

[0052] Ⅴ. Ethylene oxide is consumed as the reaction proceeds, and the pressure inside the tank body 1 drops. Under the action of the gravity of the water 42 and the nitrogen pressure, the contact rod 5 and the contact 6 are separated, so that the controller re-controls to inject ethylene oxide into the tank body 1, realizing a repeated gas-phase feeding cycle;

[0053] Ⅵ. When the total feed amount of ethylene oxide reaches the set value, continue the liquid-phase cycle; finally, flash off the product to complete the production of dimethylethanolamine; if the piston sleeve 4 is damaged or the interface sealing performance deteriorates, the water 42 flows into the tank body 1 and then into the transparent pipe between the upper feeding and liquid-phase circulation pipe 12 and the lower feeding and circulation pipe 16, which is observed by the staff and the equipment is shut down, enabling the staff to observe whether the structure inside the reactor is intact at a distance.

[0054] In summary, the present invention combines the advantages of a tubular reactor and a shell-and-tube reactor, uses a catalyst to enhance the selectivity of the reaction, reduces the reaction temperature and pressure, effectively inhibits the hydration reaction of ethylene oxide, and improves the reaction yield. In addition, a gas distributor is used to fill ethylene oxide into the tower, and a pump circulation is used to increase the contact frequency between the reactants and the catalyst, inhibit the polymerization reaction of the reactants, reduce the dosage of chemical polymerization inhibitors at the same time, and reduce the energy consumption of subsequent purification.

[0055] More importantly, a flexible piston sleeve 4 is adopted. When producing different batches or even different products, nitrogen with the same pressure as required for the reaction can be introduced according to needs, enabling the tank body 1 to supply gas continuously for a long time, avoiding reaction interruption, and improving the reaction yield. In addition, by adding water 42, not only can the piston sleeve 4 move vertically downward smoothly in the initial stage, but also when the piston sleeve 4 moves upward, it can flow to the periphery of the piston sleeve 4, avoiding the change of the connection between the piston sleeve 4 and the tank cover 2 from U-shaped to V-shaped, and further avoiding tearing of the piston sleeve 4. And when the piston sleeve 4 is damaged, it can flow into the tank body 1, and after entering the transparent pipe, the staff can directly judge the damage of the piston sleeve 4 according to the color, without the need to disassemble the tank cover 2 for inspection, which is very practical and convenient.

[0056] At the same time, the present invention is equipped with remote temperature and liquid level transmission devices, which are connected to the PLC distributed control system in the main control room, and control signals are sent to devices such as an automatic flowmeter and an electromagnetic control valve according to the transmitted data, realizing remote automatic control and improving the effect of automatic control.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A reactor for the production of dimethylethanolamine, characterized in that: it includes a tank body (1), a tank cover (2), catalyst tubes (3), a piston sleeve (4), a contact rod (5) and a contact head (6). The tank cover (2) is erected on the top of the tank body (1), and gaseous ethylene oxide and liquid dimethylamine flow through the tank body (1). A number of catalyst tubes (3) filled with granular catalysts are fixedly connected inside the tank body (1). The flexible piston sleeve (4) is fixedly connected to the bottom of the tank cover (2). There is colored water (42) and pressurized nitrogen between the piston sleeve (4) and the tank cover (2). The contact rod (5) is erected on the top of the piston sleeve (4). Two contact heads (6) are fixedly connected to the top of the tank cover (2) at intervals. The piston sleeve (4) rises to make the contact rod (5) contact the contact heads (6) and make an electrical signal connected between the contact heads (6).

2. The reactor for the production of dimethylethanolamine according to claim 1, characterized in that: the piston sleeve (4) is made of a multi-layer nylon-coated PCV fabric, and the spreading area of the piston sleeve (4) is larger than the outer diameter of the tank cover (2).

3. The reactor for the production of dimethylethanolamine according to claim 2, characterized in that: a ring-shaped top ring (41) is fixedly connected to the middle of the top end of the piston sleeve (4), and a through hole is opened at the bottom end of the top ring (41); a metal guide ring (52) is inserted on the top of the top ring (41), and two contact rods (5) are threadedly connected to the guide ring (52).

4. The reactor for the production of dimethylethanolamine according to claim 3, characterized in that: the contact rod (5) is composed of multiple metal segments, and a threaded rod (51) is fixedly connected to the bottom of each segment, and the threaded rod (51) is threadedly connected to the top of the adjacent segment.

5. The reactor for the production of dimethylethanolamine according to claim 4, characterized in that: the total amount of water (42) filled between the piston sleeve (4) and the tank cover (2) is less than the minimum volume between the piston sleeve (4) and the tank cover (2).

6. The reactor for the production of dimethylethanolamine according to claim 5, characterized in that: large-particle-size catalyst particles are filled at the bottom of the catalyst tube (3), and small-particle-size catalyst particles are filled at the top. The upper and lower ends of the catalyst tube (3) are blocked by a grid.

7. The reactor for the production of dimethylethanolamine according to claim 6, characterized in that: a number of baffle plates (31) are fixedly connected to the tank body (1) at intervals along the axial direction. The catalyst tubes (3) penetrate through the baffle plates (31); the baffle plates (31) are all provided with channels, and the channels on adjacent baffle plates (31) are not on the same vertical line.

8. The reactor for the production of dimethylethanolamine according to claim 7, characterized in that: a temperature-controlled circulating liquid inlet (13) is provided on one side of the top of the tank body (1) to introduce a liquid for heating the liquid phase into the tank body (1), and a temperature-controlled circulating liquid outlet (14) is provided on the other side of the bottom of the tank body (1) to make the liquid circulate in the tank body (1).

9. The reactor for the production of dimethylethanolamine according to claim 8, characterized in that: On one side of the top of the tank body (1), there is a feeding and liquid-phase circulation upper pipe (12), and on one side of the bottom of the tank body (1), there is a feeding and circulation lower pipe (16). The feeding and liquid-phase circulation upper pipe (12) and the feeding and circulation lower pipe (16) are connected by an externally connected transparent pipe.

10. The production method of a reactor for producing dimethylethanolamine according to claim 9, characterized in that: it includes the following steps, Ⅰ. Fill the catalyst into the catalyst tubes (3), and inject water (42) into the tank cover (2) to make the piston sleeve (4) sink downward, and at the same time, charge nitrogen into the tank cover (2) for pressurization; Ⅱ. Inject liquid dimethylamine into the tank body (1), and make the dimethylamine circulate in the tank body (1) through the feeding and liquid-phase circulation upper pipe (12) and the feeding and circulation lower pipe (16) by means of a pump; Ⅲ. Pass the circulating liquid into the tank body (1) through the temperature-controlled circulating liquid inlet (13) to raise the temperature of the liquid phase. After the temperature in the tank body (1) reaches the set temperature, inject ethylene oxide into the tank body (1). After the ethylene oxide is evenly distributed in the tank body (1) through the gas distributor arranged at the bottom of the tank body (1), it is fully mixed with the liquid-phase dimethylamine; Ⅳ. When the feeding pressure of ethylene oxide is greater than the nitrogen seal pressure in the tank cover (2), the piston sleeve (4) rises to make the contact rod (5) contact the contact head (6). After the two contact heads (6) are connected, the electrical signal in the controller is connected, and then the controller controls to stop injecting ethylene oxide into the tank body (1); Ⅴ. As the reaction proceeds, ethylene oxide is consumed, and the pressure in the tank body (1) drops. Under the action of the gravity of the water (42), the contact rod (5) and the contact head (6) are separated, so that the controller controls to inject ethylene oxide into the tank body (1) again, realizing the repeated gas-phase feeding cycle; Ⅵ. When the total feeding amount of ethylene oxide reaches the set value, continue the circulation of the liquid phase; finally, flash distill the product to discharge, and complete the production of dimethylethanolamine; wherein if the piston sleeve (4) is damaged or the interface sealing performance deteriorates, the water (42) flows into the tank body (1) and into the transparent pipe between the feeding and liquid-phase circulation upper pipe (12) and the feeding and circulation lower pipe (16), and is observed by the staff to shut down the equipment.

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