A kind of production method and production system of hexamethylenediamine

Abstract

The invention discloses a production method and a production system of hexamethylenediamine. The production method of hexamethylenediamine comprises the following steps: mixing raw materials in a premixer and then feeding them into a reactor, introducing hydrogen into the reactor for reaction; water and ethanol in the gas phase at the top of the reactor are condensed by a gas phase condenser and then flow back into the reactor, and the hydrogen in the gas phase at the top of the reactor is compressed and then fed into the reactor again to participate in the reaction; the material containing the catalyst at the bottom of the reactor is fed into a catalyst recovery tank for treatment; the material obtained from the reactor is filtered by a filter and then fed into a dealcoholization tower preheater; the material enters the dealcoholization tower after passing through the dealcoholization tower preheater, and the material is sent into a phase separator after the ethanol is removed from the dealcoholization tower through the dealcoholization tower preheater, and in the phase separator, the material is separated from the sodium hydroxide aqueous solution, and the separated material is dehydrated and subjected to a series of heavy and light removal treatments to obtain a finished product. The method of the invention has improved reaction yield, less side reactions, and a long system operation time.

Description

Technical Field

[0001] The invention relates to the technical field of chemical industry, and in particular to a production method and a production system of hexamethylenediamine. Background Art

[0002] Hexamethylenediamine is an important raw material for chemical synthesis, mainly used in the production of nylon 66 and 610 resins. The production processes of hexamethylenediamine mainly include the caprolactam method, the butadiene method and the catalytic hydrogenation method of adiponitrile. The caprolactam method and the butadiene method are only suitable for small-scale production and are gradually being eliminated due to their high production costs. The method of preparing hexamethylenediamine by catalytic hydrogenation of adiponitrile is widely used due to its simple process, high product quality and low production cost.

[0003] The method of preparing hexamethylenediamine by catalytic hydrogenation of adiponitrile is divided into high-pressure method and low-pressure method in industry. Among them, the low-pressure method uses a nickel-based catalyst, the reaction temperature is about 70-100°C, the pressure is about 1.8-2.7MPa, and the selectivity of hexamethylenediamine reaches 99%. However, in the production process of hexamethylenediamine, some side reactions also occur. The main by-products are azepan, aminocapronitrile, 1,2-diaminocyclohexane, N-ethylhexamethylenediamine, aminomethylcyclopentane, etc. Among them, azepan, 1,2-diaminocyclohexane, N-ethylhexamethylenediamine, etc. are difficult to separate from hexamethylenediamine. There are also excess ethanol, sodium hydroxide and nickel-based catalyst components in the mixture. The presence of the above substances will affect the final product high-quality refined hexamethylenediamine and the product quality of downstream users, such as chromaticity, purity and other indicators. In addition, the return pipe of the adiponitrile hydrogenation reactor is often blocked due to poor catalyst flow, which brings great pressure to the daily operation of the adiponitrile hydrogenation reaction. The main reasons for reactor blockage are the smaller catalyst particle size, higher viscosity, poorer flow properties, and the catalyst hanging on the wall and accumulating in the decanter. Once the reactor is blocked, it will seriously affect the daily operation of the adiponitrile hydrogenation reaction if it is not handled in time. The blockage will cause an increase in the hexamethylenediamine impurity generated by the adiponitrile hydrogenation reaction. Summary of the invention

[0004] In order to overcome the deficiencies of the prior art, the object of the present invention is to provide a method and a system for producing hexamethylenediamine, which can improve the reaction yield, effectively remove impurities and solid particles in the product, and minimize the energy consumption of the system.

[0005] According to one aspect of the present invention, there is provided a method for producing hexamethylenediamine, comprising the following steps:

[0006] Add a certain amount of adiponitrile, ethanol, water, catalyst, and sodium hydroxide into a premixer to obtain a uniformly mixed reaction mixture;

[0007] The reaction mixture is fed into a reactor, and hydrogen is introduced into the reactor for reaction, and a material is obtained at the top of the reactor after the reaction, wherein the reactor also includes a gas phase material at the top and a material containing a catalyst at the bottom;

[0008] The water and ethanol in the gas phase at the top of the reactor are condensed by the gas phase condenser and then flow back into the reactor. At least a portion of the liquid flowing back into the reactor flows from the upper end to the lower end of the pipeline in the reactor. The hydrogen in the gas phase at the top of the reactor passes through the gas phase condenser and enters the hydrogen compressor, and is compressed and then sent back into the reactor to participate in the reaction.

[0009] The material containing the catalyst at the bottom of the reactor is sent to a catalyst recovery tank for treatment, and the recovered catalyst is again sent to the pre-mixer as a raw material, and the recovered material is re-introduced into the system;

[0010] The material obtained from the reactor is filtered through a filter, and the catalyst obtained by filtration is sent to the catalyst recovery tank for treatment, and the filtered material is combined with the material recovered from the catalyst recovery tank and then sent to the dealcoholization tower preheater;

[0011] The material enters the dealcoholization tower after passing through the dealcoholization tower preheater. After the ethanol is removed from the material in the dealcoholization tower, the material is heat exchanged with the non-dealcoholized material through the dealcoholization tower preheater, and then sent to a phase separator. In the phase separator, the material and the sodium hydroxide aqueous solution are separated and discharged from the bottom. The separated material is dehydrated and subjected to a series of heavy and light removal treatments to obtain a finished product.

[0012] Furthermore, the mass ratio of adiponitrile, ethanol, water, catalyst and sodium hydroxide added to the premixer is (100-200):(100-200):(10-50):(0.5-15):1, and the temperature of the premixer is controlled at 10-40°C.

[0013] Furthermore, the material obtained from the reactor is first sent to a material buffer tank before being sent to the filter, and then sent to the filter from the material buffer tank. A stirring device is provided in the material buffer tank. The temperature of the material buffer tank is controlled at 50-70°C and the pressure is normal pressure.

[0014] Furthermore, the material enters the dealcoholization tower after passing through the dealcoholization tower preheater, the temperature of the dealcoholization tower is controlled at 80-140°C, ethanol is separated from the top of the dealcoholization tower, and after condensation, it is sent to the premixer as a raw material again, and the material after removing ethanol is sent to the phase separator after heat exchange with the non-dealcoholized material through the dealcoholization tower preheater.

[0015] Furthermore, the material separated from the phase separator is sent to an intermediate tank from the top of the phase separator. After entering the intermediate tank, the material is left to stand for a certain period of time so that the residual sodium hydroxide aqueous solution is separated from the material. The separated sodium hydroxide aqueous solution is discharged from the bottom of the intermediate tank, and the material at the top of the intermediate tank is sent to a dehydration tower for dehydration.

[0016] Furthermore, the material is dehydrated in the dehydration tower, the temperature of the dehydration tower is controlled at 40-150°C, and it is a vacuum operation. The waste water condensed at the top of the tower is directly discharged, and the bottom material is sent to the first de-weighting tower; the material is separated in the first de-weighting tower, the top material is sent to the first light-removing tower, and the bottom material is sent to the third de-weighting tower, and the first de-weighting tower is controlled at 120-150°C, which is a vacuum operation; the material is separated in the first light-removing tower, the low-boiling substances after condensation of the top material are discharged, and the bottom material is sent to the second light-removing tower, and the first light-removing tower is controlled at 85-130°C, which is a vacuum operation; the material is separated in the second light-removing tower, the top material is sent to the first light-removing tower for recycling, the bottom material is sent to the finished product tower, and the second light-removing tower is controlled at 85-130°C. The temperature is controlled at 80-170°C, which is a vacuum operation; the material is separated in the finished product tower, the material on the top of the tower is condensed and sent to the second light-removing tower for recycling, the finished product is taken out from the middle of the tower, and the material in the bottom of the tower is sent to the second weight-removing tower, and the temperature of the finished product tower is controlled at 90-170°C, which is a vacuum operation; the material is separated in the second weight-removing tower, the material on the top of the tower is condensed and sent to the second light-removing tower for recycling, and the material in the bottom of the tower is sent to the third weight-removing tower, and the temperature of the second weight-removing tower is controlled at 80-170°C, which is a vacuum operation; the material is separated in the third weight-removing tower, the material on the top of the tower is condensed and sent to the first light-removing tower or the intermediate tank for recycling, the heavy components of the material in the bottom of the tower are discharged, and the temperature of the third weight-removing tower is controlled at 100-170°C, which is a vacuum operation.

[0017] According to another aspect of the present invention, a production system of hexamethylenediamine is provided, comprising a premixer, a reactor, a gas phase condenser, a hydrogen compressor, a catalyst recovery tank, a material buffer tank, a filter, a dealcoholization tower preheater, a dealcoholization tower, a phase separator, an intermediate tank, a dehydration tower, a first heavy-removal tower, a first light-removal tower, a second light-removal tower, a finished product tower, a second heavy-removal tower, and a third heavy-removal tower;

[0018] The premixer is used to mix adiponitrile, ethanol, water, catalyst and sodium hydroxide, and feed the mixed raw materials into the reactor;

[0019] The reactor is suitable for introducing hydrogen, and the hydrogen reacts with the raw materials introduced from the premixer to obtain semi-finished hexamethylenediamine;

[0020] The gas phase condenser is used to condense the gas phase material on the top of the reactor, and the condensed liquid flows back to the reactor through the reflux channel. The reflux channel allows at least a part of the condensed liquid to enter the top of the pipe in the reactor. When the condensed liquid flows downward from the top of the pipe, it is suitable for washing the inner wall of the pipe of the reactor;

[0021] The hydrogen compressor is used to compress the hydrogen discharged from the gas phase condenser and send the compressed hydrogen into the reactor;

[0022] The catalyst recovery tank is used to recover the catalyst in the material at the bottom of the reactor and the catalyst filtered by the filter;

[0023] The material buffer tank is used to temporarily store the material obtained from the reactor and to feed the material into the filter;

[0024] The filter is used to filter the material, and the filtered material is sent to the dealcoholization tower preheater;

[0025] The dealcoholization tower preheater utilizes the waste heat of the dealcoholized material discharged from the dealcoholization tower to preheat the material entering the dealcoholization tower, and the preheated material is sent to the dealcoholization tower;

[0026] The dealcoholization tower is used to remove ethanol from the material, and the material after ethanol removal is sent to the phase separation tower;

[0027] The phase separation tower is used to phase separate the dealcoholized material, separate the sodium hydroxide aqueous solution from the material, and send the separated material to the intermediate tank;

[0028] The intermediate tank is used to separate the residual sodium hydroxide aqueous solution from the material, and the separated material is sent to the dehydration tower;

[0029] The dehydration tower is used to remove moisture from the material, and the dehydrated material is sent to the first deweighting tower;

[0030] The top material of the first de-weighting tower is sent to the first de-weighting tower, and the bottom material is sent to the third de-weighting tower;

[0031] The low-boiling substances of the tower top material of the first light-removal tower are condensed and discharged, and the tower bottom material is sent to the second light-removal tower;

[0032] The top material of the second light-removal tower is sent to the first light-removal tower for recycling, and the bottom material is sent to the finished product tower;

[0033] The top material of the finished product tower is condensed and sent to the second light removal tower for recycling, the finished product is taken out from the middle of the tower, and the bottom material is sent to the second heavy removal tower;

[0034] The top material of the second de-weighting tower is condensed and sent to the second de-weighting tower for recycling, and the bottom material is sent to the third de-weighting tower;

[0035] The top material of the third de-heavy tower is condensed and sent to the first de-light tower or the intermediate tank for recycling, and the heavy components of the bottom material are discharged.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] (1) The ratio of the raw materials (adiponitrile, ethanol, water, and sodium hydroxide) for synthesizing hexamethylenediamine in the present invention is reasonable, which ensures that sodium hydroxide can play its role in inhibiting the production of by-products, and reduces the amount of sodium hydroxide used, thereby reducing the risk of system slagging caused by sodium hydroxide. By designing a reasonable ratio of raw materials, the reaction yield of generating hexamethylenediamine is improved, the side reaction is reduced, and the system operation time is long;

[0038] (2) In the system for synthesizing hexamethylenediamine of the present invention, a gas phase condenser is directly arranged on the top of the reactor, thereby eliminating the conventional hydrogen-alcohol separation tower and simplifying the process. At the same time, the condensed ethanol and water can be used to continuously wash the pipe blocked by the solution in the reactor, thereby solving the problem of the reactor solution being blocked. In addition, since the present invention does not need to add new materials to clear the pipe, the balance of the system will not be destroyed.

[0039] (3) The present invention rationally recycles and utilizes various raw materials separated from the materials in various steps, which improves the purity of the product on the one hand and reduces the waste of raw materials on the other hand. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 Schematic diagram of the first part of the hexamethylenediamine production system of the present invention (the hexamethylenediamine production system is a complete and continuous system. For the convenience of display, the first part and the second part of the hexamethylenediamine production system are divided into two parts for display);

[0041] Figure 2 Schematic diagram of the second part of the hexamethylenediamine production system of the present invention;

[0042] In the figure: 101, pre-mixer; 1011, circulating water channel; 102, reactor; 103, gas phase condenser; 104, hydrogen compressor; 105, catalyst recovery tank; 106, material buffer tank; 1061, buffer tank circulating water channel; 107, filter; 108, dealcoholization tower preheater; 109, dealcoholization tower; 110, phase separator; 111, intermediate tank; 112, dehydration tower; 113, first deweighting tower; 114 , the first light-removing tower; 115, the second light-removing tower; 116, the finished product tower; 117, the second weight-removing tower; 118, the third weight-removing tower; 201, the feed channel; 202, the mixed material channel; 203, the hydrogen channel; 204, the reflux channel; 205, the catalyst recovery channel; 206, the first catalyst channel; 207, the second material channel; 208, the first material channel; 209, the third material channel; 210, the second catalyst channel. DETAILED DESCRIPTION

[0043] The present invention is further described below in conjunction with specific implementation methods. It should be noted that, under the premise of no conflict, the various embodiments or technical features described below can be arbitrarily combined to form a new embodiment.

[0044] In the description of the present invention, it should be noted that directional words, such as the terms "center", "lateral", "longitudinal", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", etc., indicating directions and positional relationships are based on the directions or positional relationships shown in the accompanying drawings, which are only for the convenience of narrating the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and cannot be understood as limiting the specific scope of protection of the present invention.

[0045] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequential order. It should be understood that the data used in this way can be interchanged in appropriate circumstances, so that the embodiments of the present application described here. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, the process, method, system, product or equipment comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or equipment.

[0046] like Figure 1 , 2As shown, the present invention provides a production system of hexamethylenediamine, which includes a premixer 101, a reactor 102, a gas phase condenser 103, a hydrogen compressor 104, a catalyst recovery tank 105, a material buffer tank 106, a filter 107, a dealcoholization tower preheater 108, a dealcoholization tower 109, a phase separator 110, an intermediate tank 111, a dehydration tower 112, a first deheaving tower 113, a first light-removing tower 114, a second light-removing tower 115, a finished product tower 116, a second deheaving tower 117, and a third deheaving tower 118.

[0047] The premixer 101 is used to mix the reaction materials to obtain a reaction mixture. The reaction materials added to the premixer 101 include adiponitrile, ethanol, water, a catalyst and sodium hydroxide. In some preferred embodiments, the mass ratio of adiponitrile, ethanol, water, a catalyst and sodium hydroxide added to the premixer 101 is (100-200): (100-200): (10-50): (0.5-15): 1.

[0048] Furthermore, a plurality of feed channels 201 are provided on the top of the premixer 101, and each reaction raw material enters the premixer 101 through each feed channel 201. A stirring device is provided in the premixer 101, and the stirring device mixes the reaction raw materials in the premixer 101 uniformly. A circulating water channel 1011 is provided outside the premixer 101, and the circulating water channel 1011 has a water inlet and a water return port. The liquid circulating in the circulating water channel 1011 is used to preheat or keep the material in the premixer 101 warm. The temperature of the premixer 101 is controlled at 10 to 40°C.

[0049] The reactor 102 is used for hydrogenation reaction. A mixing material channel 202 is provided between the reactor 102 and the premixer 101, and the reaction mixture uniformly mixed in the premixer 101 enters the reactor 102 through the mixing material channel 202. The bottom of the reactor 102 is also connected to the hydrogen channel 203, and the hydrogen used to participate in the reaction enters the reactor 102 through the hydrogen channel 203. The hydrogen entering the reactor 102 reacts with the reaction mixture to obtain semi-finished hexamethylenediamine. Preferably, the hydrogen is introduced under the condition that the temperature of the reactor 102 is maintained at 70 to 90°C and the pressure is maintained at 1.9 to 2.5MPa.

[0050] One end of the gas phase condenser 103 is connected to the top of the reactor 102, and a reflux channel 204 is provided between the gas phase condenser 103 and the reactor 102. The gas phase components at the top of the reactor 102 enter the gas phase condenser 103, and the condensed liquid flows back into the reactor 102 through the reflux channel 204. The gas phase components at the top of the reactor 102 include hydrogen, ethanol and water, wherein the ethanol and water flow back into the reactor 102 after being condensed by the gas phase condenser 103, and the hydrogen is discharged from the top of the gas phase condenser 103 and enters the hydrogen compressor 104. The outlet temperature at the top of the gas phase condenser 103 is maintained at 25-55°C.

[0051] Furthermore, the reflux channel 204 allows at least a portion of the condensed liquid to enter the top of the internal pipe of the reactor 102. When the condensed liquid flows downward from the top of the pipe, it can flush the inner wall of the pipe in the reactor 102, thereby preventing catalyst particles from clogging the pipe.

[0052] The hydrogen compressor 104 is used to compress the hydrogen discharged from the gas phase condenser 103, and send the compressed hydrogen into the reactor 102 through the hydrogen channel 203 to continue to participate in the reaction.

[0053] The catalyst recovery tank 105 is used to recover the catalyst particles in the reactor 102. A catalyst recovery channel 205 is connected between the catalyst recovery tank 105 and the bottom of the reactor 102, and the material containing catalyst particles at the bottom of the reactor 102 is sent into the catalyst recovery tank 105 through the catalyst recovery channel 205. The catalyst recovery tank 105 separates the material containing catalyst particles into catalyst, material and waste, wherein the separated catalyst is introduced into the feed channel 201 for conveying the catalyst through the first catalyst channel 206, and the separated material is sent into the dealcohol tower preheater 108 through the second material channel 207, and the separated waste is discharged from the catalyst recovery tank 105.

[0054] The material at the top of the reactor 102 is fed into the material buffer tank 106 through the first material channel 208. A stirring device is provided in the material buffer tank 106 for stirring the material in the material buffer tank 106. The material buffer tank 106 has a buffer tank circulating water channel 1061 on the outside, and the buffer tank circulating water channel 1061 has a water inlet and a water return port. The liquid circulating in the buffer tank circulating water channel 1061 is used to heat or keep the material in the material buffer tank 106 warm. The temperature of the material buffer tank 106 is controlled at 50-70°C, and the pressure is normal pressure.

[0055] The material in the material buffer tank 106 is sent to the filter 107 through the third material channel 209 for filtration. The filter 107 separates the catalyst from the material, and the material after the catalyst is removed is sent to the dealcohol tower preheater 108, and the separated catalyst is sent to the catalyst recovery tank 105.

[0056] The material from which the catalyst is removed in the filter 107 is combined with the material in the second material channel 207 and then sent to the dealcohol tower preheater 108. A second catalyst channel 210 is provided between the bottom of the filter 107 and the catalyst recovery tank 105.

[0057] The material entering the dealcoholization tower preheater 108 is heat exchanged with the material from the bottom of the dealcoholization tower 109 and then sent to the dealcoholization tower 109. The dealcoholization tower preheater 108 can use the waste heat of the bottom material of the dealcoholization tower 109 to preheat the material before entering the dealcoholization tower 109, which can effectively reduce energy consumption.

[0058] After the material enters the dealcoholization tower 109, ethanol is separated from the top of the dealcoholization tower 109, and the separated ethanol is condensed and recovered from the top of the tower and then fed into the feed channel 201 for transporting ethanol, thereby forming a recycling of ethanol. The temperature of the dealcoholization tower 109 is controlled at 80-140° C. and the pressure is normal pressure.

[0059] The material after ethanol removal enters the phase separator 110 after heat exchange in the dealcoholization tower preheater 108. The phase separator 110 uses the density difference between the material and the sodium hydroxide aqueous solution to separate the material from the sodium hydroxide aqueous solution. The light component material after separation is sent from the top of the phase separator 110 to the intermediate tank 111, and the sodium hydroxide aqueous solution at the bottom of the phase separator 110 is discharged as waste liquid.

[0060] The material sent to the intermediate tank 111 still contains a small amount of sodium hydroxide. After the intermediate tank 111 is allowed to stand, the sodium hydroxide aqueous solution is further separated from the material. The sodium hydroxide aqueous solution is discharged from the bottom of the intermediate tank 111, and the upper material is sent to the dehydration tower 112.

[0061] The material is dehydrated in the dehydration tower 112, the waste water obtained by condensation at the top of the tower is directly discharged, and the material in the bottom of the tower is sent to the first deweighting tower 113. The temperature of the dehydration tower 112 is controlled at 40-150°C and is vacuum operated.

[0062] The heavy components are separated from the materials in the first de-weighting tower 113, the materials at the top of the tower are sent to the first de-weighting tower 114, and the materials at the bottom of the tower are sent to the third de-weighting tower 118. The temperature of the first de-weighting tower 113 is controlled at 120-150°C and is operated in vacuum.

[0063] The light components of the material are separated in the first light-removing tower 114, the low-boiling substances of the top material are discharged after condensation, and the bottom material is sent to the second light-removing tower 115. The temperature of the first light-removing tower 114 is controlled at 85-130°C and is operated in vacuum.

[0064] The light components of the materials are separated in the second light-removing tower 115, the top materials are sent to the first light-removing tower 114 for recycling, and the bottom materials are sent to the finished product tower 116. The temperature of the second light-removing tower 115 is controlled at 80-170°C and is vacuum operated.

[0065] The materials are separated again in the finished product tower 116. The materials at the top of the tower are condensed and sent to the second light-removing tower 115 for recycling. The finished product is taken out from the middle of the tower, and the materials at the bottom of the tower are sent to the second heavy-removing tower 117. The temperature of the finished product tower 116 is controlled at 90-170°C and is operated in vacuum.

[0066] The heavy components are separated from the material in the second de-weighting tower 117. The top material is condensed and sent to the second de-lightening tower 115 for recycling. The bottom material is sent to the third de-weighting tower 118. The temperature of the second de-weighting tower 117 is controlled at 80-170°C and is operated in vacuum.

[0067] The heavy components of the material are separated in the third de-weighting tower 118, and the top material is condensed and sent to the first de-lightening tower 114 or the intermediate tank 111 for recycling, and the heavy components of the bottom material are discharged. The temperature of the third de-weighting tower 118 is controlled at 100-170°C and is vacuum operated.

[0068] The present invention also provides a method for producing hexamethylenediamine, comprising the following steps:

[0069] Add a certain amount of adiponitrile, ethanol, water, catalyst, and sodium hydroxide into the premixer 101 to obtain a uniformly mixed reaction mixture;

[0070] The reaction mixture is fed into the reactor 102, and hydrogen is introduced into the reactor 102 for reaction, and a material is obtained at the top of the reactor 102 after the reaction, and the reactor 102 also includes a gas phase material at the top and a material containing a catalyst at the bottom;

[0071] The water and ethanol in the gas phase at the top of the reactor 102 are condensed by the gas phase condenser 103 and then flow back into the reactor 102. At least a portion of the liquid flowing back into the reactor 102 flows from the upper end to the lower end of the pipeline in the reactor 102. The hydrogen in the gas phase at the top of the reactor 102 passes through the gas phase condenser 103 and enters the hydrogen compressor 104. After being compressed, it is sent back into the reactor 102 to participate in the reaction.

[0072] The material containing catalyst at the bottom of the reactor 102 is sent to the catalyst recovery tank 105 for treatment, and the recovered catalyst is again sent to the pre-mixer 101 as a raw material, and the recovered material is re-introduced into the system;

[0073] The material obtained from the reactor 102 is filtered through the filter 107, and the catalyst obtained by filtration is sent to the catalyst recovery tank 105 for treatment. The filtered material is combined with the material recovered from the catalyst recovery tank 105 and then sent to the dealcohol tower preheater 108;

[0074] The material passes through the dealcoholization tower preheater 108 and enters the dealcoholization tower 109. The material after ethanol removal sent out from the dealcoholization tower 109 passes through the dealcoholization tower preheater 108 and is sent to the phase separator 110 after heat exchange with the non-dealcoholized material. In the phase separator 110, the material and the sodium hydroxide aqueous solution are separated and discharged from the bottom. The separated material is dehydrated and subjected to a series of heavy and light removal treatments to obtain a finished product.

[0075] Furthermore, the mass ratio of adiponitrile, ethanol, water, catalyst and sodium hydroxide added to the premixer 101 is (100-200):(100-200):(10-50):(0.5-15):1, and the temperature of the premixer 101 is controlled at 10-40°C.

[0076] Furthermore, the material obtained from the reactor 102 is first sent to the material buffer tank 106 before being sent to the filter 107, and then sent to the filter 107 from the material buffer tank 106. A stirring device is provided in the material buffer tank 106. The temperature of the material buffer tank 106 is controlled at 50-70°C and the pressure is normal pressure.

[0077] Furthermore, the material passes through the dealcoholization tower preheater 108 and enters the dealcoholization tower 109. The temperature of the dealcoholization tower 109 is controlled at 80-140°C. Ethanol is separated from the top of the dealcoholization tower 109 and is sent to the premixer 101 as a raw material again after condensation. The material after removing ethanol passes through the dealcoholization tower preheater 108, undergoes heat exchange with the non-dealcoholized material, and is then sent to the phase separator 110.

[0078] Furthermore, the material separated from the phase separator 110 is sent to the intermediate tank 111 from the top of the phase separator 110. After entering the intermediate tank 111, the material is left to stand for a certain period of time so that the residual sodium hydroxide aqueous solution is separated from the material. The separated sodium hydroxide aqueous solution is discharged from the bottom of the intermediate tank 111, and the material at the top of the intermediate tank 111 is sent to the dehydration tower 112 for dehydration.

[0079] Further, the material is dehydrated in the dehydration tower 112, the temperature of the dehydration tower 112 is controlled at 40-150°C, and it is a vacuum operation. The waste water condensed at the top of the tower is directly discharged, and the bottom material is sent to the first de-weighting tower 113; the material is separated in the first de-weighting tower 113, the top material is sent to the first light-removing tower 114, and the bottom material is sent to the third de-weighting tower 118. The temperature of the first de-weighting tower 113 is controlled at 120-150°C, and it is a vacuum operation; the material is separated in the first light-removing tower 114, the low-boiling substances after condensation of the top material are discharged, and the bottom material is sent to the second light-removing tower 115. The temperature of the first light-removing tower 114 is controlled at 85-130°C, and it is a vacuum operation; the material is separated in the second light-removing tower 115, the top material is sent to the first light-removing tower 114 for recycling, the bottom material is sent to the finished product tower 116, and the second light-removing tower The temperature of 115 is controlled at 80-170°C, which is a vacuum operation; the material is separated in the finished product tower 116, and the top material is condensed and sent to the second light-removing tower 115 for recycling, the finished product is taken out from the middle of the tower, and the bottom material is sent to the second weight-removing tower 117. The temperature of the finished product tower 116 is controlled at 90-170°C, which is a vacuum operation; the material is separated in the second weight-removing tower 117, and the top material is condensed and sent to the second light-removing tower 115 for recycling, and the bottom material is sent to the third weight-removing tower 118. The temperature of the second weight-removing tower 117 is controlled at 80-170°C, which is a vacuum operation; the material is separated in the third weight-removing tower 118, and the top material is condensed and sent to the first light-removing tower 114 or the intermediate tank 111 for recycling, and the heavy components of the bottom material are discharged. The temperature of the third weight-removing tower 118 is controlled at 100-170°C, which is a vacuum operation.

[0080] In one specific embodiment, using the present invention Figure 1 , Figure 2 In the production system shown, the mass ratio of adiponitrile, ethanol, water, catalyst and sodium hydroxide added to the premixer 101 is 180:140:25:4:1, the reaction temperature in the reactor 102 is 70-90°C, the pressure is 1.9-2.5 MPa, and the yield of hexamethylenediamine can reach 99.5%.

[0081] The above-mentioned embodiments are only preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and substitutions made by technicians in this field on the basis of the present invention shall fall within the scope of protection required by the present invention.

Claims

1. A method for producing hexamethylenediamine, It is characterized in that The following steps are involved: Add a certain amount of adiponitrile, ethanol, water, catalyst, and sodium hydroxide into a premixer to obtain a uniformly mixed reaction mixture; The reaction mixture is fed into a reactor, and hydrogen is introduced into the reactor for reaction, and a material is obtained at the top of the reactor after the reaction, wherein the reactor also includes a gas phase material at the top and a material containing a catalyst at the bottom; The water and ethanol in the gas phase at the top of the reactor are condensed by the gas phase condenser and then flow back into the reactor. At least a portion of the liquid flowing back into the reactor flows from the upper end to the lower end of the pipeline in the reactor. The hydrogen in the gas phase at the top of the reactor passes through the gas phase condenser and enters the hydrogen compressor, and is compressed and then sent back into the reactor to participate in the reaction. The material containing the catalyst at the bottom of the reactor is sent to a catalyst recovery tank for treatment, and the recovered catalyst is again sent to the pre-mixer as a raw material, and the recovered material is re-introduced into the system; The material obtained from the reactor is filtered through a filter, and the catalyst obtained by filtration is sent to the catalyst recovery tank for treatment, and the filtered material is combined with the material recovered from the catalyst recovery tank and then sent to the dealcoholization tower preheater; The material enters the dealcoholization tower after passing through the dealcoholization tower preheater. After the ethanol is removed from the dealcoholization tower, the material passes through the dealcoholization tower preheater for heat exchange with the non-dealcoholized material, and then is sent to a phase separator. In the phase separator, the material and the sodium hydroxide aqueous solution are separated and discharged from the bottom. The separated material is dehydrated and subjected to a series of heavy and light removal treatments to obtain a finished product, wherein the mass ratio of adiponitrile, ethanol, water, catalyst, and sodium hydroxide added to the premixer is (100-200): (100-200): (10-50): (0.5-15): 1, the premixer controls the temperature at 10-40°C, and the reactor is obtained. The obtained material is first sent to a material buffer tank before being sent to the filter, and then sent to the filter from the material buffer tank. A stirring device is provided in the material buffer tank. The temperature of the material buffer tank is controlled at 50-70° C. and the pressure is normal pressure. The material enters the dealcoholization tower after passing through the dealcoholization tower preheater. The temperature of the dealcoholization tower is controlled at 80-140° C. Ethanol is separated from the top of the dealcoholization tower and is sent to the premixer as a raw material again after condensation. The material after removing ethanol is sent to a phase separator after heat exchange with the non-dealcoholized material through the dealcoholization tower preheater. The reaction temperature in the reactor is 70-90° C. and the pressure is 1.9-2.5 MPa.

2. The method for producing hexamethylenediamine according to claim 1, It is characterized in that The material separated from the phase separator is sent to the intermediate tank from the top of the phase separator. After entering the intermediate tank, the material is left to stand for a certain period of time so that the residual sodium hydroxide aqueous solution is separated from the material. The separated sodium hydroxide aqueous solution is discharged from the bottom of the intermediate tank, and the material on the upper part of the intermediate tank is sent to the dehydration tower for dehydration.

3. The method for producing hexamethylenediamine according to claim 2, It is characterized in that The material is dehydrated in the dehydration tower, the temperature of the dehydration tower is controlled at 40-150°C, and it is a vacuum operation. The wastewater condensed at the top of the tower is directly discharged, and the bottom material is sent to the first de-weighting tower; the material is separated in the first de-weighting tower, the top material is sent to the first light-removing tower, and the bottom material is sent to the third de-weighting tower. The first de-weighting tower is controlled at 120-150°C, and it is a vacuum operation; the material is separated in the first light-removing tower, the low-boiling substances after condensation of the top material are discharged, and the bottom material is sent to the second light-removing tower. The first light-removing tower is controlled at 85-130°C, and it is a vacuum operation; the material is separated in the second light-removing tower, the top material is sent to the first light-removing tower for recycling, the bottom material is sent to the finished product tower, and the second light-removing tower is controlled at 120-150°C. The temperature of the finished product tower is controlled at 90-170°C, which is a vacuum operation; the material is separated in the finished product tower, the material on the top of the tower is condensed and sent to the second light-removing tower for recycling, the finished product is taken out from the middle of the tower, the material in the bottom of the tower is sent to the second weight-removing tower, and the temperature of the finished product tower is controlled at 90-170°C, which is a vacuum operation; the material is separated in the second weight-removing tower, the material on the top of the tower is condensed and sent to the second light-removing tower for recycling, the material in the bottom of the tower is sent to the third weight-removing tower, and the temperature of the second weight-removing tower is controlled at 80-170°C, which is a vacuum operation; the material is separated in the third weight-removing tower, the material on the top of the tower is condensed and sent to the first light-removing tower or the intermediate tank for recycling, the heavy components of the material in the bottom of the tower are discharged, and the temperature of the third weight-removing tower is controlled at 100-170°C, which is a vacuum operation.

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