A device and process for continuous production of N,N-dimethylethylenediamine

Abstract

The present invention relates to a device and process for continuously producing N,N-dimethylethylenediamine, and belongs to the technical field of fine chemical synthesis. The device includes a batching device for preparing a 2-chloroethylamine hydrochloride solution, a refining tower device for completing the separation of dimethylamine and water in a dimethylamine solution, a gasification device for converting liquid dimethylamine outputted from the refining tower device into gaseous dimethylamine, a synthesis tower device for completing the reaction of synthesizing N,N-dimethylethylenediamine from the 2-chloroethylamine hydrochloride solution provided by the batching device and the gaseous dimethylamine provided by the gasification device, a recovery device for recovering dimethylamine in the reaction product outputted from the synthesis tower device, and an oil-water separation device for separating the reaction product after separating dimethylamine from an oil phase and an aqueous phase, and the process for continuously producing N,N-dimethylethylenediamine based on the device has the advantages of high automation, few on-site operators, high utilization rate of dimethylamine, high reaction efficiency, high product yield, low energy consumption, high safety, etc.

Description

Technical Field

[0001] The invention relates to a device and a process for continuously producing N,N-dimethylethylenediamine, belonging to the technical field of fine chemical synthesis. Background Art

[0002] N,N-dimethylethylenediamine, also known as dimethylethylenediamine, with CAS number 108-00-9, is an important chemical intermediate. In the field of pharmaceutical synthesis, it is mainly used to synthesize 1-dimethylaminoethyl-5-mercaptotetrazole, an intermediate of Cefotiam, antitumor drug thioxanthone, angiocarboxylic acid derris, antiarrhythmic drug procainamide, local anesthetic dibucaine, antihistamine helamine, anticholinesterase drug ambenchloramine, cefazolin sodium (Pioneer V), etc. In the field of pesticide synthesis, it is mainly used to synthesize flower inducers, and is also used in the series of additives of chromium-binding agent (such as color fixing agent, wetting agent, fiber softener and antistatic agent chromium-binding agent BCH), active cationic dye intermediates and ion exchange resin and epoxy resin curing agent, etc.

[0003] The chemical equation for producing N,N-dimethylethylenediamine using dimethylamine and 2-chloroethylamine hydrochloride is shown in equation (1), wherein the reaction equation for recovering dimethylamine by reacting dimethylamine hydrochloride with caustic soda solution is shown in equation (2).

[0004] (1) (2)

[0005] At present, the main industrial production equipment for N,N-dimethylethylenediamine is an intermittent stirred tank reactor. The specific production process is as follows: add 10% dimethylamine aqueous solution to a glass-lined reactor, cool to 15 °C while stirring, and add 2-chloroethylamine hydrochloride in batches within 0.5~1h, and the temperature does not exceed 20 °C. After the addition is completed, allow the reaction solution to naturally heat up to 37 °C, then slowly cool to 30 °C, stop cooling, and allow the feed solution to continue to naturally heat up to 38 °C, then cool the feed solution to 30 °C, and then heat it to 62 °C. The hydrogen chloride released by the tail gas is absorbed by water or alkali. After the reaction mixture is stirred at 62~65 °C for 3 h, it is cooled to 20 °C, and caustic soda flakes are added in batches within 0.5~1 h. The feed solution temperature is controlled at (25±5) °C. After the caustic soda flakes are added, continue to stir at (25±5) °C for 1 h, and then stand for stratification, and then separate the organic layer. The water layer is an emulsion, which needs to be filtered by adding diatomaceous earth. The obtained filtrate is clarified and then separated. Then the organic layers are combined, and caustic soda is added to dry and filtered. The filtrate is distilled to recover the unreacted dimethylamine first, and finally collect the fraction of 104~106 ℃, which is N,N-dimethylethylenediamine. However, the above intermittent production process has many equipment sets, insufficient automation, and the process parameters are greatly affected by human factors. It is difficult to achieve precise control, which makes the product quality unstable. Summary of the invention

[0006] In view of the problems existing in the preparation of N,N-dimethylethylenediamine based on an intermittent process, the present invention provides a device and a process for continuously producing N,N-dimethylethylenediamine. The device is easy to operate, has a high degree of automation, requires fewer on-site operators, has low energy consumption, and is safe to operate. In addition, the continuous production of N,N-dimethylethylenediamine based on the device has high reaction efficiency, high product yield, and high dimethylamine utilization rate.

[0007] The objectives of the present invention are achieved through the following technical solutions.

[0008] A device for continuously producing N,N-dimethylethylenediamine, comprising batching equipment, refining tower equipment, gasification equipment, synthesis tower equipment, recovery equipment and oil-water separation equipment;

[0009] The batching equipment is used to prepare a 2-chloroethylamine hydrochloride solution of a desired concentration and transport it to the middle and upper part of the tower body of the synthesis tower equipment;

[0010] The refining tower equipment is used to separate dimethylamine and water in the dimethylamine solution;

[0011] The gasification equipment is used to convert the liquid dimethylamine output from the top of the tower body of the refining tower equipment into gaseous dimethylamine and transport it to the bottom of the tower body of the synthesis tower equipment;

[0012] The synthesis tower equipment is used to complete the reaction of 2-chloroethylamine hydrochloride solution and gaseous dimethylamine to synthesize N,N-dimethylethylenediamine;

[0013] The recovery device is used to recover dimethylamine in the reaction product output from the bottom of the tower body of the synthesis tower device, and transport the recovered dimethylamine to the gasification device for gasification and reuse;

[0014] The oil-water separation equipment is used to separate the reaction product after separating dimethylamine into an oil phase and a water phase, wherein the oil phase is the target product N,N-dimethylethylenediamine, and the water phase is an aqueous solution containing NaCl.

[0015] Furthermore, the batching equipment includes two batching tanks with stirring, the batching tanks are used to prepare 2-chloroethylamine hydrochloride solution of required concentration for standby use, and the two batching tanks (one is marked as batching tank I and the other is marked as batching tank II) are used alternately, specifically as follows: when batching tank I is conveying materials to the synthesis tower equipment, batching tank II needs to complete the preparation of 2-chloroethylamine hydrochloride solution, when the liquid level of batching tank I is lower than a certain scale, it is switched to batching tank II to convey materials to the synthesis tower equipment. At this time, batching tank I needs to prepare 2-chloroethylamine hydrochloride solution. After the preparation is completed, wait for the liquid level of batching tank II to be lower than a certain scale to complete the switch.

[0016] Further, the refining tower equipment includes a refining tower body, a refining tower reboiler and a refining tower condenser, the refining tower reboiler is installed at the bottom of the refining tower body, the refining tower condenser is installed at the top of the refining tower body, the dimethylamine solution completes the separation of dimethylamine and water inside the refining tower body, pure dimethylamine is obtained at the top of the refining tower body, and waste water is obtained at the bottom of the refining tower body. Among them, the refining tower body can be a packed tower or a plate tower, and the theoretical number of plates of the whole tower of the refining tower body is preferably 6 to 20, the number of plates of the rectifying section is preferably 2 to 10, and the number of plates of the stripping section is preferably 3 to 10.

[0017] Furthermore, the gasification equipment includes an intermediate storage tank and a gasifier; the inlet of the intermediate storage tank is connected to the top of the tower body of the refining tower equipment, the outlet of the intermediate storage tank is connected to the liquid inlet of the gasifier, and the gas outlet of the gasifier is connected to the bottom of the tower body of the synthesis tower equipment.

[0018] Furthermore, the synthesis tower equipment includes a synthesis tower body and a synthesis tower condenser, the synthesis tower condenser is installed at the top of the synthesis tower body, and the synthesis tower condenser is used to condense the gas phase generated at the top of the synthesis tower body and reflux it into the synthesis tower body. Preferably, the synthesis tower body is an airlift loop reactor, and a special internal component structure can be installed inside the airlift loop reactor, which is conducive to further improving the gas content of the internal solution, reducing the bubble size, and strengthening the material mixing reaction.

[0019] Further, the recovery equipment includes a static mixer, a recovery tower body, a recovery tower reboiler and a recovery tower condenser;

[0020] The static mixer is provided with a NaOH liquid inlet for completing a mixing reaction between the NaOH solution and the reaction product output from the bottom of the tower body of the synthesis tower equipment;

[0021] The recovery tower reboiler is installed at the bottom of the recovery tower body, and the recovery tower condenser is installed at the top of the recovery tower body; the recovery tower body is used to separate dimethylamine from the secondary reaction products output from the static mixer, and the dimethylamine obtained at the top of the recovery tower body is condensed by the recovery tower condenser and then transported to the gasification equipment for gasification, and the secondary reaction product after the separation of dimethylamine (i.e., an oil-water mixed solution containing N,N-dimethylethylenediamine and NaCl) is obtained at the bottom of the recovery tower body.

[0022] Among them, the recovery tower body can be a packed tower or a plate tower. The number of theoretical plates of the recovery tower body is preferably 6 to 31, the number of plates in the distillation section is preferably 3 to 15, and the number of plates in the stripping section is preferably 3 to 16.

[0023] Furthermore, the oil-water separation equipment is an oil-water separation tank.

[0024] The process for continuously producing N,N-dimethylethylenediamine based on the device of the present invention comprises the following specific steps:

[0025] The 2-chloroethylamine hydrochloride solution of the required concentration is transported to the middle and upper part of the tower body of the synthesis tower equipment through the batching equipment; the dimethylamine solution is separated from the dimethylamine and water through the refining tower equipment, the waste water generated by the separation is recovered, and the dimethylamine generated by the separation is transported to the gasification equipment for gasification, and the gasified dimethylamine enters the bottom of the tower body of the synthesis tower equipment in the form of gas phase; the 2-chloroethylamine hydrochloride solution and the gaseous dimethylamine react inside the tower body of the synthesis tower equipment to generate N,N-dimethylethylenediamine; the reaction product of the synthesis tower equipment enters the recovery equipment, is mixed with the NaOH solution and reacts to form a secondary reaction product, and then dimethylamine is recovered from the secondary reaction product, and the recovered dimethylamine is transported to the gasification equipment for gasification and reuse, and the secondary reaction product after the dimethylamine is separated enters the oil-water separation equipment to separate the oil phase and the water phase, the separated oil phase is N,N-dimethylethylenediamine, and the separated water phase is the aqueous solution containing NaCl and is transported to the wastewater treatment.

[0026] The mass fraction of the 2-chloroethylamine hydrochloride solution prepared by the batching equipment is 20~60%.

[0027] When dimethylamine and water are separated inside the tower body of the refining tower equipment, the operating pressure inside the tower body is normal pressure~0.35MPaG, the operating temperature at the top of the tower body is 6~55°C, and the operating temperature at the bottom of the tower body is 100~155°C. Preferably, when the operating pressure inside the tower body is less than 0.23 MPaG, the operating temperature at the top of the tower body is less than 40°C, and the operating temperature at the bottom of the tower body is less than 140°C; when the operating pressure at the top of the refining tower is 0.23~0.35 MPaG, the operating temperature at the top of the tower body is 40~55°C, and the operating temperature at the bottom of the tower body is 140~155°C.

[0028] When N,N-dimethylethylenediamine is synthesized inside the tower body of the synthesis tower equipment, the molar ratio of 2-chloroethylamine hydrochloride in the 2-chloroethylamine hydrochloride solution entering the tower body to the gaseous dimethylamine entering the tower body is 1: (3.05-6), the operating pressure inside the tower body is normal pressure-0.35 MPaG, and the operating temperature at the top of the tower body is 30-85°C. Preferably, when the operating pressure inside the tower body is less than 0.23 MPaG, the operating temperature at the top of the tower body is less than 41°C; when the operating pressure inside the tower body is 0.23-0.35 MPaG, the operating temperature at the top of the tower body is 41-85°C.

[0029] For the reaction product and NaOH solution entering the recovery device, the molar ratio of N,N-dimethylethylenediamine in the reaction product to NaOH in the NaOH solution is 1:(2.01~2.4). When dimethylamine is recovered inside the tower body of the recovery tower device, the operating pressure inside the tower body is normal pressure~0.35 MPaG, the operating temperature at the top of the tower is 6~55°C, and the operating temperature at the bottom of the tower is 102~160°C. Preferably, when dimethylamine is recovered inside the tower body of the recovery tower device, when the operating pressure inside the tower body is less than 0.23 MPaG, the operating temperature at the top of the tower is less than 40°C, and the operating temperature at the bottom of the tower is less than 142°C; when the operating pressure inside the tower body is 0.23~0.35 MPaG, the operating temperature at the top of the tower is 40~55°C, and the operating temperature at the bottom of the tower is 142~160°C.

[0030] Beneficial effects:

[0031] (1) When the dimethylamine solution is used directly, nitrogen needs to be used as the circulation power of the circulation reactor, and a compressor needs to be set up to realize the internal circulation of the nitrogen reactor. In addition, when the dimethylamine solution is used, the amount of water in the system increases, and more salt-containing wastewater is generated in the subsequent process, which increases the cost of sewage treatment. The present invention converts the dimethylamine solution into gaseous dimethylamine through a refining tower device and a gasification device, and eliminates the compressor under the dimethylamine solution working condition. Although the additional refining tower device and gasification device increase the equipment investment, the reduction of moving equipment, maintenance cost and accident probability are lower. At the same time, when the gaseous dimethylamine is used as the circulation power, there is a reaction not only in the liquid material, but also at the gas-liquid interface, which is conducive to reducing the residence time of the reactor and improving the reaction efficiency. In addition, the process wastewater generated after the dimethylamine distillation can be recycled, reducing the operation and environmental protection costs.

[0032] (2) The intermediate storage tanks installed in the gasification equipment are used to store the pure dimethylamine produced by the refining tower and the recovery tower, which is conducive to improving the operational flexibility and stability of the entire system. In addition, if some faults occur in the synthesis tower equipment, emergency repairs will take a certain amount of time. Due to the buffer of the intermediate storage tanks, the refining tower and the recovery tower can be kept at normal load for a short period of time or at low load for a long time.

[0033] (3) The dimethylamine in the reaction tower body is excessive to ensure the conversion rate of the amination reaction. The excess dimethylamine and dimethylamine released after the reaction of dimethylamine hydrochloride with sodium hydroxide are recovered through the recovery tower body and enter the dimethylamine intermediate storage tank for recycling, thereby improving the utilization rate of raw materials. Compared with the recovery of dimethylamine in the intermittent process, the continuous process recovers pure dimethylamine. The energy consumption of recovering the same quality of pure dimethylamine is lower and the recovery rate of dimethylamine is higher. This is because: the intermittent process uses distillation to obtain dimethylamine solution, and a certain amount of water is also extracted together with dimethylamine by evaporation and then condensation; the intermittent process has serious unorganized emissions, resulting in a lower recovery rate of dimethylamine than the continuous process.

[0034] (4) The amination reaction in the intermittent process is carried out in a reactor, and the heat removal effect is poor. Therefore, the operating parameters tend to be conservative, the drop rate is slow, and the material reaction temperature is low, which results in a long reaction residence time and low production efficiency. The only way to increase the output is to add a reactor and its supporting facilities. The amination reaction in the continuous process of the present invention is completed in the synthesis tower body. The gas-liquid flow in the synthesis tower body is intense, and the mass transfer and heat transfer speed are fast. The amination reaction releases heat to gasify the liquid dimethylamine in the synthesis tower body, and then enters the heat exchanger set at the top of the tower to condense and liquefy, and then flows back to the reactor through the reflux pump. This process is fast, the heat removal effect is good, the reaction temperature is high, the reaction speed is fast, and the production efficiency is high.

[0035] (5) When 2-chloroethylamine hydrochloride solution and gaseous dimethylamine react in the synthesis tower body, the materials in the synthesis tower body are saturated. The increase in pressure leads to an increase in the temperature of the system, and the reaction residence time will be slightly shortened. Otherwise, the residence time will be slightly prolonged, but it has no effect on the conversion rate. Adjust the feed amount of the two to ensure that the 2-chloroethylamine hydrochloride reacts completely. If the 2-chloroethylamine hydrochloride is excessive, the conversion rate will be reduced and the product yield will be reduced.

[0036] In summary, the device of the present invention has a simple structure, is easy to operate, has a high degree of automation, requires fewer on-site operators, has low operating energy consumption and is highly safe. The device can continuously produce N,N-dimethylethylenediamine with a high product yield, high reaction efficiency and high utilization rate of dimethylamine. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 Schematic diagram of the structure of the device for continuously producing N,N-dimethylethylenediamine in the embodiment.

[0038] Among them, 1-batch tank I, 2-batch tank II, 3-refining tower body, 4-refining tower reboiler, 5-refining tower condenser, 6-intermediate storage tank, 7-gasifier, 8-synthesis tower body, 9-synthesis tower condenser, 10-static mixer, 11-recovery tower body, 12-recovery tower reboiler, 13-recovery tower condenser; 14-oil-water separation tank, A-2-chloroethylamine hydrochloride, B-water, C-2-chloroethylamine hydrochloride solution, D-dimethylamine solution, E-liquid dimethylamine, F-waste water, G-gaseous dimethylamine, H-reaction product, I-NaOH solution, J-secondary reaction product, K-recovered dimethylamine, L-secondary reaction product after separation of dimethylamine, M-aqueous solution containing NaCl, NN,N-dimethylethylenediamine. DETAILED DESCRIPTION

[0039] The present invention is further described below in conjunction with specific embodiments, wherein the methods are conventional methods unless otherwise specified, and the raw materials can be obtained from public commercial channels unless otherwise specified. In addition, in the description of the present invention, it should be understood that the orientations or positional relationships indicated by the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside", "outside", etc. are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present invention.

[0040] In the following embodiments, the device for continuously producing N,N-dimethylethylenediamine includes batching equipment, refining tower equipment, gasification equipment, synthesis tower equipment, recovery equipment and oil-water separation equipment;

[0041] like Figure 1 As shown, the batching equipment includes two batching tanks with stirring, which are used to prepare 2-chloroethylamine hydrochloride solution C of required concentration, and alternately transport 2-chloroethylamine hydrochloride solution C to the middle and upper part of the synthesis tower body 8 of the synthesis tower equipment; wherein the two batching tanks are simply referred to as batching tank Ⅰ 1 and batching tank Ⅱ 2, and the process of alternating transportation is as follows: when batching tank Ⅰ 1 transports 2-chloroethylamine hydrochloride solution C to the synthesis tower body 8, batching tank Ⅱ 2 needs to complete the preparation of 2-chloroethylamine hydrochloride solution C, and when the liquid level of batching tank Ⅰ 1 is lower than a certain scale, it is switched to batching tank Ⅱ 2 to transport 2-chloroethylamine hydrochloride solution C to the synthesis tower body 8. At this time, batching tank Ⅰ 1 needs to prepare 2-chloroethylamine hydrochloride solution C, and after the preparation is completed, wait for the liquid level of batching tank Ⅱ 2 to be lower than a certain scale to complete the switch;

[0042] like Figure 1 As shown, the refining tower equipment includes a refining tower body 3, a refining tower reboiler 4 and a refining tower condenser 5, the refining tower reboiler 4 is installed at the bottom of the refining tower body 3, the refining tower condenser 5 is installed at the top of the refining tower body 3, the dimethylamine solution D completes the separation of dimethylamine and water inside the refining tower body 3, pure dimethylamine is obtained at the top of the refining tower body 3, and waste water F is obtained at the bottom of the refining tower body 3; wherein, the refining tower body 3 can be a packed tower or a plate tower, the theoretical number of plates of the whole tower of the refining tower body 3 is preferably 6 to 20, the number of plates of the rectifying section is preferably 2 to 10, and the number of plates of the stripping section is preferably 3 to 10;

[0043] like Figure 1 As shown, the gasification equipment includes an intermediate storage tank 6 and a gasifier 7; the inlet of the intermediate storage tank 6 is connected to the refining tower condenser 5 of the refining tower equipment, the outlet of the intermediate storage tank 6 is connected to the liquid inlet of the gasifier 7, and the gas outlet of the gasifier 7 is connected to the bottom of the synthesis tower body 8 of the synthesis tower equipment; the liquid dimethylamine E condensed by the refining tower condenser 5 is converted into gaseous dimethylamine G by the gasification equipment and transported to the bottom of the synthesis tower body 8;

[0044] like Figure 1 As shown, the synthesis tower equipment includes a synthesis tower body 8 and a synthesis tower condenser 9. The synthesis tower condenser 9 is installed on the top of the synthesis tower body 8. The synthesis tower condenser 9 is used to condense the gas phase generated at the top of the synthesis tower body 8 and reflux it into the synthesis tower body; preferably, the synthesis tower body 8 is an airlift loop reactor to ensure that the 2-chloroethylamine hydrochloride solution C and the gaseous dimethylamine G fully react to generate N,N-dimethylethylenediamine N;

[0045] like Figure 1As shown, the recovery equipment includes a static mixer 10, a recovery tower body 11, a recovery tower reboiler 12 and a recovery tower condenser 13; the feed port of the static mixer 10 is connected to the bottom of the synthesis tower body 8, the discharge port of the static mixer 10 is connected to the recovery tower body 11, the static mixer 10 is also provided with a NaOH liquid inlet, the recovery tower reboiler 12 is installed at the bottom of the recovery tower body 11, and the recovery tower condenser 13 is installed at the top of the recovery tower body 11; the static mixer 10 is used to complete the mixing reaction of the NaOH solution I and the reaction product H output by the synthesis tower body 8, the recovery tower body 11 is used to separate dimethylamine from the secondary reaction product J output by the static mixer, the dimethylamine obtained at the top of the recovery tower body 11 is condensed by the recovery tower condenser 13 and then transported to the gasification equipment for gasification, and the secondary reaction product L after the dimethylamine is separated is obtained at the bottom of the recovery tower body 11;

[0046] like Figure 1 As shown, the oil-water separation equipment is an oil-water separation tank, which is used to separate the secondary reaction product L after separating dimethylamine into oil phase and water phase, and the oil phase is the target product N,N-dimethylethylenediamine N, and the water phase is the aqueous solution M containing NaCl.

[0047] The process for continuously producing N,N-dimethylethylenediamine based on the device has the following specific steps:

[0048] The two batching tanks of the batching equipment alternately transport 2-chloroethylamine hydrochloride solution C with a mass fraction of 20-60% to the middle and upper part of the synthesis tower body; the dimethylamine solution D passes through the refining tower body 3 to complete the separation of dimethylamine and water, and the waste water F generated by the separation is recovered. The separated dimethylamine is transported to the intermediate storage tank and then enters the gasifier for gasification, and then the gaseous dimethylamine G enters the bottom of the synthesis tower body 8; the 2-chloroethylamine hydrochloride solution C reacts with the gaseous dimethylamine G inside the synthesis tower body 8 to generate N,N-dimethylethylenediamine N; the synthesis tower body 8 is used for the synthesis of dimethylamine. The reaction product of the tower body 8 enters the static mixer 10, is mixed with the NaOH solution I and reacts to form a secondary reaction product J, and then dimethylamine is recovered from the secondary reaction product J through the recovery tower body 11, and the recovered dimethylamine K is transported to the intermediate storage tank 6 for reuse. The secondary reaction product L after the dimethylamine is separated and output from the bottom of the recovery tower body 11 enters the oil-water separation tank 14 to complete the separation of the oil phase and the water phase. The separated oil phase is N,N-dimethylethylenediamine N, and the separated water phase is the aqueous solution M containing NaCl and is transported to wastewater treatment.

[0049] When dimethylamine and water are separated inside the tower body of the refining tower equipment, the operating pressure inside the tower body is normal pressure~0.35MPaG, the operating temperature at the top of the tower body is 6~55°C, and the operating temperature at the bottom of the tower body is 100~155°C. Preferably, when the operating pressure inside the tower body is less than 0.23 MPaG, the operating temperature at the top of the tower body is less than 40°C, and the operating temperature at the bottom of the tower body is less than 140°C; when the operating pressure at the top of the refining tower is 0.23~0.35 MPaG, the operating temperature at the top of the tower body is 40~55°C, and the operating temperature at the bottom of the tower body is 140~155°C.

[0050] When N,N-dimethylethylenediamine N is synthesized inside the tower body of the synthesis tower equipment, the molar ratio of 2-chloroethylamine hydrochloride A in the 2-chloroethylamine hydrochloride solution C entering the tower body to the gaseous dimethylamine G entering the tower body is 1: (3.05-6), the operating pressure inside the tower body is normal pressure-0.35 MPaG, and the operating temperature at the top of the tower body is 30-85°C. Preferably, when the operating pressure inside the tower body is less than 0.23 MPaG, the operating temperature at the top of the tower body is less than 41°C; when the operating pressure inside the tower body is 0.23-0.35 MPaG, the operating temperature at the top of the tower body is 41-85°C.

[0051] For the reaction product H and NaOH solution I entering the recovery device, the molar ratio of N,N-dimethylethylenediamine N in the reaction product H to NaOH in the NaOH solution I is 1:(2.01~2.4). The operating pressure inside the recovery tower body of the recovery equipment is normal pressure~0.35 MPaG, the tower top operating temperature is 6~55 ℃, and the tower bottom operating temperature is 102~160 ℃. Preferably, when the operating pressure inside the recovery tower body 11 is less than 0.23 MPaG, the tower top operating temperature is less than 40 ℃, and the tower bottom operating temperature is less than 142 ℃; when the operating pressure inside the recovery tower body 11 is 0.23~0.35 MPaG, the tower top operating temperature is 40~55 ℃, and the tower bottom operating temperature is 142~160 ℃.

[0052] Example 1

[0053] Taking a device with a production capacity of 50 t / a N,N-dimethylethylenediamine and an annual operating time of 7200 h as an example, the refining tower body 3 used is a packed tower with a tower diameter of 100 mm, 15 theoretical plates for the whole tower, 7 theoretical plates for the rectifying section, and 8 theoretical plates for the stripping section; the synthesis tower body 8 is a gas lift loop reactor with a tower diameter of 150 mm; the recovery tower body 11 is a packed tower with 15 theoretical plates, a tower diameter of 100 mm, 7 theoretical plates for the rectifying section, and 8 theoretical plates for the stripping section;

[0054] Under normal operating conditions: 20 ℃ 40% dimethylamine solution D is input into the refining tower body 3 at a flow rate of 8.88 kg / h, the operating pressure inside the tower body is atmospheric pressure, the tower top temperature is 6 ℃, the tower bottom temperature is 102 ℃, and the pure dimethylamine produced from the tower top enters the intermediate storage tank 6 at a flow rate of 3.55 kg / h; the 40% 2-chloroethylamine hydrochloride solution C prepared in the batching tank enters the middle and upper part of the synthesis tower body 8 at a flow rate of 36.22 kg / h, and the gaseous dimethylamine G after gasification in the vaporizer 7 enters the bottom of the synthesis tower body 8 at a flow rate of 11.19 kg / h. The molar ratio of 2-chloroethylamine hydrochloride A and dimethylamine in the two feeds is 1:3.15. The two feeds react inside the tower body to generate N,N-dimethylethylenediamine N. The operating pressure inside the tower body is atmospheric pressure, the tower top temperature is 30 ℃; the reaction product H output from the synthesis tower body 8 reacts with the NaOH solution I with a flow rate of 16.54 kg / h and a mass fraction of 40% in the static mixer 10, and the molar ratio of N,N-dimethylethylenediamine N to NaOH in the two streams is 1:2.1; the secondary reaction product J output from the static mixer 10 enters the recovery tower body 11, the operating pressure inside the tower body is normal pressure, the tower top temperature is 6 ℃, the tower bottom temperature is 108 ℃, and the pure dimethylamine produced from the tower top enters the intermediate storage tank 6 at a flow rate of 7.64 kg / h; the secondary reaction product L after the dimethylamine is separated output from the recovery tower body 11 enters the oil-water separation tank 14, and after oil-water separation, the oil phase is the target product N,N-dimethylethylenediamine N with a purity greater than 99% and a yield of 95.4%, and the water phase is an aqueous solution M containing NaCl and is transported to wastewater treatment.

[0055] Example 2

[0056] On the basis of Example 1, only the operating pressure, tower top temperature and tower bottom temperature of the refining tower body 3, the synthesis tower body 8 and the recovery tower body 11 are changed, and other conditions remain unchanged, and the target product N,N-dimethylethylenediamine N with a purity greater than 99% and a yield of 98.2% is obtained accordingly. In this embodiment, the internal operating pressure of the refining tower body 3 is 0.35 MPaG, the tower top temperature is 52°C, and the tower bottom temperature is 147°C; the internal operating pressure of the synthesis tower body 8 is 0.35 MPaG, the tower top temperature is 85°C; the internal operating pressure of the recovery tower body 11 is 0.35 MPaG, the tower top temperature is 52°C, and the tower bottom temperature is 152°C.

[0057] Example 3

[0058] Taking a device with a production capacity of 70 t / a N,N-dimethylethylenediamine and an annual operating time of 7200 h as an example, the refining tower body 3 used is a packed tower with a tower diameter of 100 mm, 19 theoretical plates for the whole tower, 9 theoretical plates for the rectifying section, and 10 theoretical plates for the stripping section; the synthesis tower body 8 is a gas lift loop reactor with a tower diameter of 200 mm; the recovery tower body 11 is a packed tower with 20 theoretical plates, with a tower diameter of 100 mm, 10 theoretical plates for the rectifying section, and 10 theoretical plates for the stripping section;

[0059] Under normal operating conditions: 20 ℃ 40% dimethylamine solution D is input into the refining tower body 3 at a flow rate of 12.43 kg / h, the operating pressure inside the tower body is atmospheric pressure, the tower top temperature is 6 ℃, the tower bottom temperature is 102 ℃, and the pure dimethylamine produced from the tower top enters the intermediate storage tank 6 at a flow rate of 4.97 kg / h; the 32% 2-chloroethylamine hydrochloride solution C prepared in the batching tank enters the middle and upper part of the synthesis tower body 8 at a flow rate of 36.22 kg / h, and the gaseous dimethylamine G after gasification by the vaporizer 7 enters the bottom of the synthesis tower body 8 at a flow rate of 19.90 kg / h. The molar ratio of 2-chloroethylamine hydrochloride A and dimethylamine in the two feeds is 1:4. The two feeds react in the tower body to generate N,N-dimethylethylenediamine N. The operating pressure inside the tower body is atmospheric pressure, and the tower top temperature is 33 ℃; the reaction product H output from the synthesis tower body 8 and the flow rate are 24.26 kg / h and a NaOH solution I with a mass fraction of 40% reacts in a static mixer 10, and the molar ratio of N,N-dimethylethylenediamine N to NaOH in the two streams is 1:2.1; the secondary reaction product J output by the static mixer 10 enters a recovery tower body 11, the operating pressure inside the tower body is normal pressure, the tower top temperature is 6 ° C, the tower bottom temperature is 108 ° C, and the pure dimethylamine produced from the tower top enters the intermediate storage tank 6 at a flow rate of 14.92 kg / h; the secondary reaction product L after the dimethylamine is separated output by the recovery tower body 11 enters an oil-water separation tank 14, and after oil-water separation, the oil phase is the target product N,N-dimethylethylenediamine N with a purity greater than 99% and a yield of 96.9%, and the water phase is an aqueous solution M containing NaCl and is transported to wastewater treatment.

[0060] Example 4

[0061] Taking a device with a production capacity of 70 t / a N,N-dimethylethylenediamine and an annual operating time of 7200 h as an example, the refining tower body 3 used is a packed tower with a tower diameter of 100 mm, 20 theoretical plates for the whole tower, 10 theoretical plates for the rectifying section, and 10 theoretical plates for the stripping section; the synthesis tower body 8 is a gas lift loop reactor with a tower diameter of 200 mm; the recovery tower body 11 is a packed tower with 30 theoretical plates, with a tower diameter of 100 mm, 14 theoretical plates for the rectifying section, and 16 theoretical plates for the stripping section;

[0062] Under normal operating conditions: 20 ℃ 40% dimethylamine solution D is input into the refining tower body 3 at a flow rate of 12.41 kg / h, the operating pressure inside the tower body is 0.35 MPaG, the tower top temperature is 52 ℃, the tower bottom temperature is 147 ℃, and the pure dimethylamine produced from the tower top enters the intermediate storage tank 6 at a flow rate of 4.97 kg / h; the 45% 2-chloroethylamine hydrochloride solution C prepared in the batching tank enters the middle and upper part of the synthesis tower body 8 at a flow rate of 28.43 kg / h, and the gaseous dimethylamine G after gasification in the vaporizer 7 enters the bottom of the synthesis tower body 8 at a flow rate of 24.43 kg / h. The molar ratio of 2-chloroethylamine hydrochloride A and dimethylamine in the two feeds is 1:5. The two feeds react inside the tower body to generate N,N-dimethylethylenediamine N. The operating pressure inside the tower body is 0.35 MPaG, the tower top temperature is 76 ℃; the reaction product H output from the synthesis tower body 8 reacts with the NaOH solution I with a flow rate of 25.37kg / h and a mass fraction of 40% in the static mixer 10, and the molar ratio of N,N-dimethylethylenediamine N to NaOH in the two streams is 1:2.3; the secondary reaction product J output from the static mixer 10 enters the recovery tower body 11, the operating pressure inside the tower body is 0.35 MPaG, the tower top temperature is 52 ℃, the tower bottom temperature is 153 ℃, and the pure dimethylamine produced from the tower top enters the intermediate storage tank 6 at a flow rate of 19.89kg / h; the secondary reaction product L after the dimethylamine is separated output from the recovery tower body 11 enters the oil-water separation tank 14, and after oil-water separation, the oil phase is the target product N,N-dimethylethylenediamine N with a purity greater than 99% and a yield of 98.7%, and the water phase is an aqueous solution M containing NaCl and is transported to wastewater treatment.

[0063] In summary, the above are only preferred embodiments of the present invention and are not intended to limit the protection scope of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A process for continuously producing N,N-dimethylethylenediamine, characterized in that: The devices used in the process include batching equipment, refining tower equipment, gasification equipment, synthesis tower equipment, recovery equipment and oil-water separation equipment; The batching equipment is used to prepare a 2-chloroethylamine hydrochloride solution of a desired concentration and transport it to the middle and upper part of the tower body of the synthesis tower equipment; The refining tower equipment is used to separate dimethylamine and water in the dimethylamine solution; The gasification equipment is used to convert the liquid dimethylamine output from the top of the tower body of the refining tower equipment into gaseous dimethylamine and transport it to the bottom of the tower body of the synthesis tower equipment; The synthesis tower equipment is used to complete the reaction of 2-chloroethylamine hydrochloride solution and gaseous dimethylamine to synthesize N,N-dimethylethylenediamine; The recovery device is used to recover dimethylamine in the reaction product output from the bottom of the tower body of the synthesis tower device, and transport the recovered dimethylamine to the gasification device for gasification and reuse; The oil-water separation equipment is used to separate the reaction product after separating dimethylamine into an oil phase and a water phase, wherein the oil phase is the target product N,N-dimethylethylenediamine, and the water phase is an aqueous solution containing NaCl; The specific steps of the process are as follows: The 2-chloroethylamine hydrochloride solution of the required concentration is transported to the middle and upper part of the tower body of the synthesis tower equipment through the batching equipment; the dimethylamine solution is separated from the dimethylamine and water through the refining tower equipment, the waste water generated by the separation is recovered, and the separated dimethylamine is transported to the gasification equipment for gasification, and the gasified dimethylamine enters the bottom of the tower body of the synthesis tower equipment in the form of gas phase; the 2-chloroethylamine hydrochloride solution and the gaseous dimethylamine react inside the tower body of the synthesis tower equipment to generate N,N-dimethylethylenediamine; the reaction product of the synthesis tower equipment enters the recovery equipment, is mixed with the NaOH solution and reacts to form a secondary reaction product, and then dimethylamine is recovered from the secondary reaction product, and the recovered dimethylamine is transported to the gasification equipment for gasification and reuse, and the secondary reaction product after the dimethylamine is separated enters the oil-water separation equipment to separate the oil phase and the water phase, the separated oil phase is N,N-dimethylethylenediamine, and the separated water phase is the aqueous solution containing NaCl and is transported to the wastewater treatment; The mass fraction of 2-chloroethylamine hydrochloride solution prepared by the batching equipment is 20~60%; When dimethylamine and water are separated inside the refining tower, the operating pressure inside the tower is normal pressure ~ 0.35 MPaG, the operating temperature at the top of the tower is 6 ~ 55 °C, and the operating temperature at the bottom of the tower is 100 ~ 155 °C; When synthesizing N,N-dimethylethylenediamine inside the tower body of the synthesis tower equipment, the molar ratio of 2-chloroethylamine hydrochloride in the 2-chloroethylamine hydrochloride solution entering the tower body to the gaseous dimethylamine entering the tower body is 1:(3.05~6), the operating pressure inside the tower body is normal pressure~0.35 MPaG, and the operating temperature at the top of the tower body is 30~85℃; For the reaction product and NaOH solution entering the recovery equipment, the molar ratio of N,N-dimethylethylenediamine in the reaction product to NaOH in the NaOH solution is 1:(2.01~2.4); when dimethylamine is recovered inside the tower body of the recovery tower equipment, the operating pressure inside the tower body is normal pressure~0.35 MPaG, the operating temperature at the top of the tower is 6~55 ℃, and the operating temperature at the bottom of the tower is 102~160 ℃.

2. A process for continuous production of N,N-dimethylethylenediamine according to claim 1, characterized in that: When dimethylamine and water are separated inside the refining tower, when the operating pressure inside the tower is less than 0.23 MPaG, the operating temperature at the top of the tower is less than 40°C, and the operating temperature at the bottom of the tower is less than 140°C; when the operating pressure at the top of the refining tower is 0.23~0.35 MPaG, the operating temperature at the top of the tower is 40~55°C, and the operating temperature at the bottom of the tower is 140~155°C; When synthesizing N,N-dimethylethylenediamine inside the tower body of the synthesis tower equipment, when the operating pressure inside the tower body is less than 0.23MPaG, the operating temperature at the top of the tower body is less than 41°C; when the operating pressure inside the tower body is 0.23~0.35MPaG, the operating temperature at the top of the tower body is 41~85°C; When dimethylamine is recovered inside the tower body of the recovery tower equipment, when the operating pressure inside the tower body is less than 0.23 MPaG, the operating temperature at the top of the tower is less than 40°C, and the operating temperature at the bottom of the tower is less than 142°C; when the operating pressure inside the tower body is 0.23~0.35MPaG, the operating temperature at the top of the tower is 40~55°C, and the operating temperature at the bottom of the tower is 142~160°C.

3. A process for continuous production of N,N-dimethylethylenediamine according to claim 1, characterized in that: The batching equipment comprises two batching tanks with stirring, the batching tanks are used to prepare 2-chloroethylamine hydrochloride solution of required concentration for standby use, and the two batching tanks alternately transport the 2-chloroethylamine hydrochloride solution to the synthesis tower equipment.

4. A process for continuous production of N,N-dimethylethylenediamine according to claim 1, characterized in that: The gasification equipment includes an intermediate storage tank and a gasifier; the inlet of the intermediate storage tank is connected to the top of the tower body of the refining tower equipment, the outlet of the intermediate storage tank is connected to the liquid inlet of the gasifier, and the gas outlet of the gasifier is connected to the bottom of the tower body of the synthesis tower equipment.

5. A process for continuous production of N,N-dimethylethylenediamine according to claim 1, characterized in that: The synthesis tower equipment comprises a synthesis tower body and a synthesis tower condenser; the synthesis tower condenser is installed on the top of the synthesis tower body.

6. A process for continuous production of N,N-dimethylethylenediamine according to claim 5, characterized in that: The synthesis tower body is an airlift loop reactor.

7. A process for continuously producing N,N-dimethylethylenediamine according to any one of claims 1 to 6, characterized in that: The refining tower equipment comprises a refining tower body, a refining tower reboiler and a refining tower condenser; the refining tower reboiler is installed at the bottom of the refining tower body, and the refining tower condenser is installed at the top of the refining tower body.

8. A process for continuous production of N,N-dimethylethylenediamine according to claim 7, characterized in that: The recovery equipment includes a static mixer, a recovery tower body, a recovery tower reboiler and a recovery tower condenser; The static mixer is provided with a NaOH liquid inlet for completing a mixing reaction between the NaOH solution and the reaction product output from the bottom of the tower body of the synthesis tower equipment; The recovery tower reboiler is installed at the bottom of the recovery tower body, and the recovery tower condenser is installed at the top of the recovery tower body; the recovery tower body is used to separate dimethylamine from the secondary reaction products output from the static mixer, and the dimethylamine obtained at the top of the recovery tower body is condensed by the recovery tower condenser and then transported to the gasification equipment for gasification, and the secondary reaction product after the dimethylamine is separated is obtained at the bottom of the recovery tower body.

9. A process for continuous production of N,N-dimethylethylenediamine according to claim 8, characterized in that: The refining tower body is a packed tower or a plate tower. The theoretical number of plates of the refining tower body is 6 to 20, while the number of plates of the rectifying section is 2 to 10, and the number of plates of the stripping section is 3 to 10. The recovery tower body is a packed tower or a plate tower. The theoretical number of plates of the recovery tower body is 6 to 31, while the number of plates in the distillation section is 3 to 15, and the number of plates in the stripping section is 3 to 16.

Images