High-purity tetramethyl hexamethylenediamine preparation system

Abstract

The utility model relates to the field of chemical production, and provides a high-purity tetramethyl hexamethylenediamine preparation system. Comprising a reaction unit and a rectification unit, the reaction unit comprises an autoclave, a stirring device is installed in the autoclave, a hydrogen feeding distributor is installed at the tail end of the bottom of a stirring shaft, the hydrogen feeding distributor comprises a distribution plate and a plurality of distribution pipes installed on the distribution plate, and the distribution pipes are communicated with an inner cavity of the distribution plate. And the center of the bottom of the distribution plate is communicated with the extension pipeline corresponding to the gas inlet through a rotary joint. Through the structural design of the hydrogen feeding distributor, it is ensured that hydrogen can uniformly enter the bottom of the high-pressure kettle from the inside of the hydrogen feeding distributor, so that the hydrogen can be in full contact with and react with materials in the high-pressure kettle in the rising process; the reacted mixed solution is pressed out from the bottom under the pressure of the autoclave and then sent into a rectification unit for subsequent treatment, and finally the high-purity tetramethyl hexamethylenediamine finished product is obtained after rectification of the rectification unit.

Description

Technical Field

[0001] The utility model relates to the field of chemical production, in particular to a high-purity tetramethylhexanediamine preparation system. Background Art

[0002] Tetramethylhexanediamine is synthesized from 1,6-hexanediamine and polyformaldehyde in the presence of hydrogen and a catalyst. During the reaction, the raw materials and hydrogen are fully mixed in the autoclave and undergo a synthetic reaction. After the reaction, the finished product, solvent, raw materials, etc. are distilled by the distillation unit, the solvent is recycled for secondary use, and the final finished product enters the packaging branch for filling.

[0003] Hydrogen generally contacts the raw materials from the bottom of the reactor at a certain pressure from bottom to top. Generally, stirring is used to increase the contact time and contact surface to promote the reaction. Hydrogen needs to diffuse evenly in the autoclave. Hydrogen can drive the raw materials and catalysts to disperse evenly, increase the reaction rate, and generate products with more stable properties. However, the air intake method and air intake pressure can easily lead to concentrated accumulation of hydrogen in the autoclave, causing safety hazards. Therefore, the addition of hydrogen directly affects the speed of the synthesis reaction, the degree of reaction, and the content of impurities such as raw materials in the finished product. Summary of the invention

[0004] In order to enable the raw materials to react fully and quickly and reduce the content of impurities in the finished product, the utility model provides a high-purity tetramethylhexanediamine preparation system.

[0005] The technical solution adopted by the utility model is:

[0006] A high-purity tetramethylhexanediamine preparation system comprises a reaction unit and a distillation unit, wherein the reaction unit comprises an autoclave, a heat exchange jacket is installed on the outside of the autoclave, a stirring device is installed in the autoclave, a gas inlet, a raw material inlet and a mixed liquid outlet are arranged on the upper cover of the autoclave, the gas inlet is connected to a hydrogen buffer tank through a pipeline, the raw material inlet is connected to a formaldehyde high-level tank through a pipeline, and the mixed liquid outlet is connected to the distillation unit through a pipeline; the distillation unit comprises an evaporator and a distillation tower, the mixed liquid outlet of the autoclave is connected to the mixed liquid inlet at the top of the evaporator; the gas inlet, the raw material inlet and the mixed liquid outlet are respectively extended to the bottom of the autoclave through extension pipelines, and the stirring device is arranged on the upper cover of the autoclave ... The stirring device comprises a stirring shaft, the top of which is connected to the reducer on the upper cover of the autoclave, and the stirring shaft is provided with a plurality of stirring blades distributed up and down along the length direction thereof; a hydrogen distributor is provided at the end of the bottom of the stirring shaft, and the hydrogen distributor comprises a distribution plate and a plurality of distribution pipes installed on the distribution plate, the distribution plate is a hollow circular plate, the top surface of the distribution plate is fixedly connected to the lower end of the stirring shaft, a plurality of evenly distributed distribution pipes are installed on the bottom surface of the distribution plate, the distribution pipes are tube bodies of curled and sintered multi-layer steel wire meshes, the outer walls of the distribution pipes are densely covered with ventilation holes, each of the distribution pipes is connected with the inner cavity of the distribution plate, and the bottom center of the distribution plate is connected with the extension pipe corresponding to the gas inlet through a rotary joint.

[0007] Furthermore, a filter and a sedimentation tank are installed between the mixed liquid outlet of the autoclave and the evaporator, the mixed liquid in the autoclave enters the filter through a pipeline, and the filtered mixed liquid enters the sedimentation tank through a pipeline, and the liquid outlet on one side of the sedimentation tank is connected to the material inlet at the top of the evaporator through a pipeline.

[0008] Furthermore, a steam outlet and a tower reflux port are provided at the top of the evaporator, the steam outlet is connected to the lower part of the distillation tower through a pipeline, and the bottom of the distillation tower is connected to the tower reflux port through a pipeline; the steam outlet at the top of the distillation tower is connected to a condenser through a pipeline, and the condensate outlet thereof is connected to the top of the distillation tower, the fore distillation tank and the finished product tank through a pipeline and valve control.

[0009] Furthermore, the bottom of the finished product tank is connected to a packaging branch and a recycling branch through pipelines and valves respectively, a bag filter is installed on the packaging branch, a pump is installed on the recycling branch, and the pump is connected to the reaction unit through a pipeline.

[0010] Furthermore, the formaldehyde high-level tank is connected to a formaldehyde preparation kettle, the bottom of the formaldehyde preparation kettle is connected to the top of the formaldehyde high-level tank through a magnetic pump, the top of the formaldehyde preparation kettle is connected to a methanol recycling tank through a pipeline, and the methanol recycling tank is connected to the recycling branch.

[0011] Furthermore, the top of the evaporator is connected to a crude product high-level tank, and the bottom of the evaporator is connected to the crude product high-level tank through a circulation pump.

[0012] After adopting the above technical scheme, the beneficial effects of the utility model are:

[0013] The structural design of the hydrogen distributor ensures that hydrogen can evenly enter the bottom of the autoclave from the hydrogen distributor, and the stirring shaft drives the rotation of the hydrogen distributor, and the stirring device stirs, so that the hydrogen can fully contact and react with the material in the high pressure during the rising process; the mixed liquid after the reaction is pressed out from the bottom by the pressure of the autoclave and then sent to the distillation unit for subsequent treatment, which can fully guarantee the reaction time, so that the content of the finished product entering the distillation unit is high, and finally after distillation in the distillation unit, a high-purity tetramethylhexanediamine finished product is obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is the reaction principle diagram of the utility model.

[0015] Figure 2 Schematic diagram of the structure of the hydrogen distributor.

[0016] In the figure: autoclave 1, extension pipeline 2, hydrogen buffer tank 3, formaldehyde high-level tank 4, formaldehyde preparation kettle 5, magnetic pump 6, methanol recycling tank 7, stirring device 8, hydrogen distributor 9, distribution plate 91, distribution pipe 92, filter 10, sedimentation tank 11, evaporation kettle 12, distillation tower 13, condenser 14, fore distillation tank 15, finished product tank 16, circulation pump 17, crude product high-level tank 18, packaging branch 19, recycling branch 20, bag filter 21. DETAILED DESCRIPTION

[0017] The specific implementation of the utility model is further described in detail below with reference to the accompanying drawings:

[0018] like Figure 1 As shown, a high-purity tetramethylhexanediamine preparation system consists of two parts: a reaction unit and a distillation unit, and is used for the synthesis and distillation of tetramethylhexanediamine.

[0019] The reaction unit mainly includes an autoclave 1, and a heat exchange jacket is installed on the outside of the autoclave 1 to ensure that the temperature of the synthesis reaction meets the requirements. A gas inlet, a raw material inlet and a mixed liquid outlet are provided on the upper cover of the autoclave 1, and the gas inlet, the raw material inlet and the mixed liquid outlet are respectively extended to the bottom of the autoclave 1 through an extension pipe 2. The gas inlet is connected to a hydrogen buffer tank 3 through a pipeline for participating in the reaction through hydrogen. The raw material inlet is connected to a formaldehyde high-level tank 4 through a pipeline for passing formaldehyde raw materials and reacting with 1,6-hexanediamine in the autoclave 1. The formaldehyde high-level tank 4 is connected to a formaldehyde preparation kettle 5, and the bottom of the formaldehyde prepared in the formaldehyde preparation kettle 5 is sent to the formaldehyde high-level tank 4 through a magnetic pump 6. A methanol recycling tank 7 is connected to the top of the formaldehyde preparation kettle 5 through a pipeline, and the methanol recycling tank 7 is used to recover the solvent methanol in the reaction system and send it to the formaldehyde preparation kettle 5 for repeated use.

[0020] A stirring device 8 is installed in the autoclave 1. The stirring device 8 includes a stirring shaft. The top of the stirring shaft is connected to the reducer on the upper cover of the autoclave, and is driven by the reducer to rotate at a low speed. The stirring shaft is equipped with upper and lower groups of stirring blades. The stirring device 8 can achieve full mixing of the internal raw materials and promote the occurrence of the reaction.

[0021] A hydrogen distributor 9 is installed at the end of the bottom of the stirring shaft. The hydrogen distributor 9 consists of a distribution plate 91 and a plurality of evenly distributed distribution pipes 92 installed on the distribution plate. The distribution plate 91 is a hollow circular plate. The top surface of the distribution plate 91 is fixedly connected to the lower end of the stirring shaft. The bottom surface of the distribution plate 91 is installed with a plurality of evenly distributed distribution pipes 92. The distribution pipe 92 is a tube body formed by curling and sintering multiple layers of steel wire mesh. Due to the presence of the steel wire mesh mesh, the outer wall of the sintered distribution pipe is densely covered with vents. The inner diameter of the distribution pipe 92 is 50-100mm, and the aperture of the vents on the distribution pipe 92 is 500-1000um. Each distribution pipe 92 is connected to the inner cavity of the distribution plate 92. A rotary joint is provided at the bottom center of the distribution plate 92, and the gas inlet is connected to the rotary joint through the extension pipe 2.

[0022] The hydrogen at a certain pressure in the hydrogen buffer tank 3 enters the distribution plate 91 and is then evenly dispersed to the surroundings by the distribution pipe 92. Under the rotation of the distribution plate 91 and the action of the stirring paddle, the hydrogen fully disturbs and mixes the internal catalyst and raw materials, promoting the occurrence of the forward reaction. After the reaction is completed, the excess hydrogen gathers at the top of the autoclave 1 and continues to react with the raw materials.

[0023] After the reaction is completed, the mixed liquid is output from the mixed liquid outlet through the extended pipeline under the pressure of the autoclave 1, and enters the settling tank 11 through the pipeline after being filtered by the filter 10. The filter 10 is used to filter the catalyst particles and foam in the mixed liquid. The settling tank 11 is used to further settle the small particles of the catalyst. The clear liquid on the upper layer of the settling tank 11 enters the distillation unit through the pipeline.

[0024] The distillation unit is composed of an evaporator 12, a distillation tower 13, a condenser 14, a pre-distillation tank 15, and a finished product tank 16. The mixed liquid in the autoclave 1 enters the evaporator 12 after filtration and sedimentation. The evaporator 12 is provided with two heat exchange systems, using steam and hot oil as heat exchange media respectively. The evaporator 12 evaporates the low-boiling point solvent, raw materials, etc. and the high-boiling point finished product therein respectively. The top of the evaporator 12 is connected to a crude product high-level tank, and the bottom of the evaporator 12 is connected to the crude product high-level tank 18 through a circulating pump 17.

[0025] The steam of the low-boiling-point material evaporated in the evaporator 12 enters the distillation tower 13 from the steam outlet on the top thereof, and the distillation tower 13 continues to be distilled. The low-boiling-point material enters the condenser 14 from the steam outlet on the top of the distillation tower 13 to be condensed, and the high-boiling-point finished product gathers at the bottom of the distillation tower 13 and flows back to the evaporator 12 through the pipeline; the condensate outlet of the condenser 14 is sent to the top of the distillation tower 13 for reflux, or to the front distillation tank 15 or to the finished product tank 16 through the pipeline and valve control.

[0026] The fore distillate in the fore distillation tank 16 flows back to the evaporation kettle 12 through the pipeline, and the finished product tank 16 is used to collect condensate at different temperature sections. The bottom of the finished product tank 16 is connected to the packaging branch 19 and the recycling branch 20 through pipelines and valves. During low-temperature distillation, the solvent enters the finished product tank 16 for collection, and the solvent is sent to the methanol recycling tank 7 for secondary use through the pump on the recycling branch 20. During high-temperature distillation, the finished product tank 16 is used to collect the finished product, and the finished product can be directly filled after being filtered by the bag filter 21 on the packaging branch 19.

Claims

1. A high-purity tetramethylhexanediamine preparation system, comprising a reaction unit and a distillation unit, wherein the reaction unit comprises an autoclave, a heat exchange jacket is installed on the outside of the autoclave, a stirring device is installed in the autoclave, a gas inlet, a raw material inlet and a mixed liquid outlet are arranged on the upper cover of the autoclave, the gas inlet is connected to a hydrogen buffer tank through a pipeline, the raw material inlet is connected to a formaldehyde high-level tank through a pipeline, and the mixed liquid outlet is connected to the distillation unit through a pipeline; the distillation unit comprises an evaporator and a distillation tower, and the mixed liquid outlet of the autoclave is connected to the mixed liquid inlet at the top of the evaporator; characterized in that The gas inlet, the raw material inlet and the mixed liquid outlet are respectively extended to the bottom of the autoclave through extension pipes. The stirring device includes a stirring shaft. The top of the stirring shaft is connected to the reducer on the upper cover of the autoclave. The stirring shaft is equipped with multiple groups of stirring blades distributed up and down along its length direction; a hydrogen distributor is installed at the end of the bottom of the stirring shaft. The hydrogen distributor includes a distribution plate and multiple distribution pipes installed on the distribution plate. The distribution plate is a hollow circular plate. The top surface of the distribution plate is fixedly connected to the lower end of the stirring shaft. The bottom surface of the distribution plate is equipped with multiple evenly distributed distribution pipes. The distribution pipe is a tube body made of multi-layer steel wire mesh curled and sintered. The outer wall of the distribution pipe is densely covered with ventilation holes. Each of the distribution pipes is connected to the inner cavity of the distribution plate. The bottom center of the distribution plate is connected to the extension pipe corresponding to the gas inlet through a rotating joint.

2. A high-purity tetramethylhexanediamine preparation system according to claim 1, characterized in that: A filter and a sedimentation tank are installed between the mixed liquid outlet of the autoclave and the evaporator. The mixed liquid in the autoclave enters the filter through a pipeline, and the filtered mixed liquid enters the sedimentation tank through a pipeline. The liquid outlet on one side of the sedimentation tank is connected to the material inlet at the top of the evaporator through a pipeline.

3. A high-purity tetramethylhexanediamine preparation system according to claim 1, characterized in that: A steam outlet and a tower reflux port are provided at the top of the evaporator, the steam outlet is connected to the lower part of the distillation tower through a pipeline, and the bottom of the distillation tower is connected to the tower reflux port through a pipeline; the steam outlet at the top of the distillation tower is connected to a condenser through a pipeline, and the condensate outlet thereof is respectively connected to the top of the distillation tower, the fore distillation tank and the finished product tank through a pipeline and valve control.

4. A high-purity tetramethylhexanediamine preparation system according to claim 3, characterized in that: The bottom of the finished product tank is connected to a packaging branch and a recycling branch through pipelines and valves respectively. A bag filter is installed on the packaging branch, and a pump is installed on the recycling branch. The pump is connected to the reaction unit through a pipeline.

5. A high-purity tetramethylhexanediamine preparation system according to claim 4, characterized in that: The formaldehyde high-level tank is connected to a formaldehyde preparation kettle, the bottom of the formaldehyde preparation kettle is connected to the top of the formaldehyde high-level tank through a magnetic pump, the top of the formaldehyde preparation kettle is connected to a methanol recycling tank through a pipeline, and the methanol recycling tank is connected to the recycling branch.

6. A high-purity tetramethylhexanediamine preparation system according to claim 1 or 4, characterized in that: The top of the evaporating kettle is connected with a crude product high-level tank, and the bottom of the evaporating kettle is connected with the crude product high-level tank through a circulating pump.

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