Production system for low-chlorine-content siloxane and linear body thereof

Abstract

The utility model discloses a production system of siloxane with low chlorine content and a linear body thereof, which comprises a raw material conveying pipe, the outlet end of the raw material conveying pipe is connected with a first dechlorination device, the material outlet of the first dechlorination device is communicated with the material inlet of a primary heat exchanger, and the material outlet of the primary heat exchanger is connected with a light component removal tower. A material outlet in the bottom of the light component removal tower is communicated with a material inlet of a second-stage heat exchanger, a material outlet of the second-stage heat exchanger is connected with a second dechlorination device, a material outlet of the second dechlorination device is communicated with a material inlet of a third-stage heat exchanger, and a material outlet of the third-stage heat exchanger is connected with a loop line separation tower; a top outlet of the loop separation tower is connected with a loop storage tank, a material outlet at the bottom of the loop separation tower is communicated with a material inlet of a fourth-stage heat exchanger, a material outlet of the fourth-stage heat exchanger is connected with a third dechlorination device, and a material outlet of the third dechlorination device is connected with a line storage tank. The system has the advantages of being reasonable in structure, easy to implement, thorough in dechlorination and good in product quality.

Description

Technical Field

[0001] The utility model belongs to the technical field of organic silicon production and processing, and specifically relates to a production system of low-chlorine-content siloxane and its linear body. Background Art

[0002] In the production process of silicone, the hydrolysis process of dimethyldichlorosilane occupies a core position in the production of silicone and is an indispensable part of the silicone industry chain. Its reaction product siloxane is an important intermediate monomer of silicone and a basic monomer for the preparation of silicone oil, silicone rubber, silicone resin and other materials. The principle of the hydrolysis process of dimethyldichlorosilane is that a certain amount of dimethyldichlorosilane and water react under acidic conditions to generate polydimethylsiloxane and a certain amount of hydrogen chloride. The reaction equation is as follows: (n+m)(CH 3 ) 2 SiCl 2 +(n+m+1)H 2 0→HO[(CH 3 ) 2 SiO] m H+[(CH 3 ) 2 SiO] n+2(m+n)HCl; The hydrolysis process of dimethyldichlorosilane is a dechlorination process. After hydrolysis, the chlorine content in the product polysiloxane is theoretically non-existent. However, due to the small density difference between polysiloxane and water, it is difficult to completely separate siloxane from chlorine. The chlorine content in the hydrolyzed siloxane is still greater than 10ppm. The chlorine in silicone products can be divided into combined chlorine and free chlorine. Combined chlorine refers to the chlorine element connected to siloxane by chemical bonds. Free chlorine refers to free chloride ions. Most of the chlorine in the product is free chloride ions. The chlorine content in the hydrolyzed siloxane product has always been a key indicator for measuring the quality of silicone products. The chlorine content not only reflects the degree of control of the hydrolysis reaction of the enterprise to a certain extent, but also too high a chlorine content will affect the stable operation of the subsequent process and the product quality. In addition, the chlorine content requirements of silicone products required in the field of high-tech are also extremely stringent. In order to meet the demand for materials in the field of high-tech, the chlorine content in the hydrolyzate must be reduced as much as possible. In the existing technology, the system device for removing chloride ions from hydrolyzed siloxane in the industry is mainly a water washing system. The hydrolyzate is washed by water in a multi-stage water washing method. Although the purpose of removing chlorine can be achieved, the effect of removing chlorine is not thorough. The chlorine content in the siloxane after washing is still above 10ppm, which cannot meet the current high-tech field The requirements for the chlorine content of organic silicon products, which will significantly reduce the utilization rate of siloxane intermediates and affect the marketing income of the enterprise. At the same time, due to the high chlorine content, it will seriously affect the efficiency of subsequent loop separation and affect the product quality of cyclic polysiloxane and linear polysiloxane after separation. Therefore, it is an objective need to develop a production system for low-chlorine siloxane and its linear body that has a reasonable structure, is easy to implement, has thorough dechlorination, and can improve product quality. Summary of the invention

[0003] The utility model aims to provide a production system of low-chlorine-content siloxane and its linear body which has reasonable structure, is easy to implement, can completely dechlorinate and can improve product quality.

[0004] The purpose of the utility model is achieved in this way, including a raw material conveying pipe, the outlet end of the raw material conveying pipe is connected with a first dechlorination device, the material outlet of the first dechlorination device is communicated with the material inlet of a primary heat exchanger, the material outlet of the primary heat exchanger is connected with a light component removal tower, the top of the light component removal tower is provided with a light component outlet, the material outlet at the bottom of the light component removal tower is communicated with the material inlet of a secondary heat exchanger, the material outlet of the secondary heat exchanger is connected with a second dechlorination device, the material outlet of the second dechlorination device is communicated with the material inlet of a tertiary heat exchanger, the material outlet of the tertiary heat exchanger is connected with a loop separation tower, the top outlet of the loop separation tower is connected with a loop storage tank, the material outlet at the bottom of the loop separation tower is communicated with the material inlet of a fourth heat exchanger, the material outlet of the fourth heat exchanger is connected with a third dechlorination device, and the material outlet of the third dechlorination device is connected with a loop storage tank.

[0005] Compared with the existing hydrolysis dechlorination device, the advantages of this device are: first, the system is equipped with a first dechlorination device, a first-stage heat exchanger, a light removal tower, a second-stage heat exchanger, a second dechlorination device and a third-stage heat exchanger at the front end of the loop separation tower. By combining temperature change with adsorption dechlorination, not only can the chloride ions in the hydrolyzed siloxane be efficiently removed and the chlorine content in the hydrolyzed siloxane be reduced, but also the light component impurities such as alkanes and olefins in the hydrolyzed siloxane can be more thoroughly removed, the purity of the hydrolyzed siloxane is improved, and the impurity content is reduced. First, the hydrolyzed siloxane after dechlorination and impurity removal enters the annular separation tower to separate the annular polysiloxane and the linear polysiloxane, which can achieve a better separation effect; second, this system is equipped with a four-stage heat exchanger and a third dechlorination device at the rear end of the annular separation tower. It also uses the method of changing the temperature combined with adsorption dechlorination to more thoroughly remove the chloride ions in the linear polysiloxane, and the chloride ion content in the linear polysiloxane can be reduced to below 1ppm, achieving a better dechlorination effect, thereby greatly improving the production quality of the product. In summary, this system has the advantages of reasonable structure, easy implementation, thorough dechlorination, and good product quality, and is easy to promote and use. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 It is a schematic diagram of the overall structure of the utility model;

[0007] Figure 2 It is a schematic structural diagram of the first dechlorination device 1;

[0008] In the figure: 1-first dechlorination device, 101-tank body, 102-upper head, 103-lower head, 104-heating jacket, 105-flower plate, 106-dechlorination material, 107-first liquid distribution plate, 108-second liquid distribution plate, 109-liquid distribution hole, 110-flow guide pipe, 111-glass fiber membrane, 112-observation window, 113-anti-vortex plate, 114-partition plate, 2-primary heat exchanger, 3-dehydrogenation tower, 4-secondary heat exchanger, 5-second dechlorination device, 6-third stage heat exchanger, 7-loop separation tower, 8-loop storage tank, 9-fourth stage heat exchanger, 10-third dechlorination device, 11-line storage tank. DETAILED DESCRIPTION

[0009] The present invention is further described below in conjunction with the accompanying drawings, but the present invention is not limited in any way. Any changes or improvements made based on the teachings of the present invention belong to the protection scope of the present invention.

[0010] like Figures 1-2As shown, the utility model includes a raw material conveying pipe, the outlet end of the raw material conveying pipe is connected with a first dechlorination device 1, the material outlet of the first dechlorination device 1 is communicated with the material inlet of a primary heat exchanger 2, the primary heat exchanger 2 is used for heating the hydrolyzate siloxane, the primary heat exchanger 2 adopts the shell and tube heat exchanger used in the prior art, the heating medium of the primary heat exchanger 2 adopts steam, the material outlet of the primary heat exchanger 2 is connected with a light component removal tower 3, the top of the light component removal tower 3 is provided with a light component outlet, the material outlet at the bottom of the light component removal tower 3 is communicated with the material inlet of a secondary heat exchanger 4, the light component removal tower 3 adopts the structure used in the prior art, the material outlet of the secondary heat exchanger 4 is connected with a second dechlorination device 5, the secondary heat exchanger 5 is used for cooling the hydrolyzate siloxane, the secondary heat exchanger 5 adopts the shell and tube heat exchanger structure used in the prior art, and the cooling medium in the secondary heat exchanger 5 adopts cold air for cooling, The material outlet of the second dechlorination device 5 is communicated with the material inlet of the tertiary heat exchanger 6, and the material outlet of the tertiary heat exchanger 6 is connected with a loop separation tower 7. The tertiary heat exchanger 6 is used for heating the hydrolyzed siloxane. The tertiary heat exchanger 6 adopts the shell-and-tube heat exchanger used in the prior art. The heating medium of the tertiary heat exchanger 6 adopts steam. The loop separation tower 7 adopts the packed tower structure used in the prior art. The top outlet of the loop separation tower 7 is connected with a ring body storage tank 8. The material outlet at the bottom of the loop separation tower 7 is communicated with the material inlet of the quaternary heat exchanger 9. The material outlet of the quaternary heat exchanger 9 is connected with a third dechlorination device 10. The quaternary heat exchanger 9 is used for cooling the hydrolyzed siloxane. The quaternary heat exchanger 9 adopts the shell-and-tube heat exchanger structure used in the prior art. The cooling medium in the quaternary heat exchanger 9 adopts cold air for cooling. The material outlet of the third dechlorination device 10 is connected with a wire body storage tank 11.

[0011] The production process of this system is: first, the hydrolyzed siloxane with a chlorine content greater than 10ppm from the upstream is sent to the first dechlorination device 1 for the first dechlorination treatment, and then the hydrolyzed siloxane after the first dechlorination treatment is sent to the primary heat exchanger 2 for the first heating and temperature rise. The purpose of heating and temperature rise is to enter the light-removal tower 3 to remove light component impurities such as alkanes and olefins; then the hydrolyzed siloxane after the first heating and temperature rise is sent to the light-removal tower 3 for impurity removal treatment, and the separated light component impurities such as alkanes and olefins are discharged from the top outlet of the light-removal tower 3, and the hydrolyzed siloxane after impurity removal is discharged from the bottom of the light-removal tower 3. The process technology of the light-removal tower 3 is to use the different boiling points of the components in the hydrolyzed siloxane to separate the light component impurities in the hydrolyzed siloxane; the hydrolyzed siloxane taken out from the outlet of the tower kettle of the light-removal tower 3 is sent to the secondary heat exchanger 4 for the first cooling treatment, and the hydrolyzed siloxane after the light-removal treatment is cooled. The purpose is that too high or too low temperature will reduce the performance of the dechlorination material, and the hydrolyzed siloxane is cooled for better dechlorination effect; the hydrolyzed siloxane after the first cooling treatment is sent to the second dechlorination device 5 for the second dechlorination treatment, and then the hydrolyzed siloxane after the second dechlorination treatment is cooled. The treated hydrolyzed siloxane is sent to the tertiary heat exchanger 6 for a second heating and temperature increase in order to increase the temperature of the hydrolyzed siloxane entering the loop separation tower 7. Because the principle of line-loop separation is to achieve separation through the difference in boiling points between the linear body and the ring body in the hydrolyzed siloxane, it is necessary to heat and temperature increase the hydrolyzed siloxane; finally, the hydrolyzed siloxane after the second heating and temperature increase is sent to the loop separation tower 7 for loop separation, and the separated cyclic polysiloxane is extracted from the tower top outlet of the loop separation tower 7 and loaded into the ring body storage tank 8, and the separated linear polysiloxane is extracted from the tower bottom outlet of the loop separation tower 7. The linear polysiloxane is separated from the ring body due to the different boiling points, so that the cyclic polysiloxane and the linear polysiloxane can be separated efficiently; the linear polysiloxane extracted from the tower bottom outlet of the ring separation tower 7 is sent to the four-stage heat exchanger 9 for a second cooling treatment, and the separated linear polysiloxane is cooled. The purpose is that too high or too low temperature will reduce the performance of the dechlorination material, and the linear polysiloxane is cooled to achieve a better dechlorination effect; the linear polysiloxane after the second cooling treatment is sent to the third dechlorination device 10 for a third dechlorination treatment, and the linear polysiloxane after the third dechlorination treatment is then loaded into the linear body storage tank 11. This system uses the method of changing temperature combined with adsorption dechlorination, which can not only reduce the chloride ion content in the hydrolyzed siloxane, but also can more thoroughly remove light component impurities such as alkanes and olefins in the hydrolyzed siloxane, improve the purity of the hydrolyzed siloxane, reduce the impurity content, improve the efficiency of subsequent loop separation, and further improve the product quality of linear polysiloxane.

[0012] Furthermore, the first dechlorination device 1, the second dechlorination device 5 and the third dechlorination device 10 have the same structure, and all include a tank body 101 and an upper head 102 and a lower head 103 installed at both ends of the tank body 101. The upper head 102 and the lower head 103 can be flange-connected with the tank body 101 to facilitate inspection and maintenance. A heating jacket 104 is provided at intervals on the outer side of the tank body 101. The lower part of the heating jacket 104 is provided with a medium inlet, and the upper part is provided with a medium outlet. The tank body 101 is heated by the heating jacket 104 to ensure temperature stability during the dechlorination process. A liquid distribution component is installed on the upper part of the tank body 101. The liquid distribution component can evenly distribute the hydrolyzed siloxane entering the dechlorination material 106 area to allow it to be mixed with the dechlorination material 106. The dechlorination material 106 is fully contacted. Two flower plates 105 are installed at intervals in the upper and lower parts of the tank body 101 below the liquid distribution component. The two flower plates 105 are filled with dechlorination material 106. A loading port is provided on the tank body 101 on the upper side of the dechlorination material 106, and a discharging port is provided on the tank body on the lower side of the dechlorination material 106. Control valves are provided on the loading port and the discharging port. The dechlorination material 106 can be replaced by using the loading port and the discharging port. When in use, the hydrolyzate siloxane enters from the material inlet of the upper head 102, is evenly distributed by the liquid distribution component, and enters the desulfurization material 106 area. After being adsorbed by the dechlorination material 106, the chloride ions in the hydrolyzate are adsorbed by the dechlorination material 106, and the hydrolyzate siloxane is discharged from the material outlet at the bottom of the lower head 103.

[0013] Preferably, in order to achieve a better liquid distribution effect, the liquid distribution component includes a first liquid distribution plate 107 and a second liquid distribution plate 108 spaced apart from each other, the first liquid distribution plate 107 is evenly processed with a plurality of liquid distribution holes 109, and a plurality of guide tubes 110 are evenly installed on the first liquid distribution plate 107 between the plurality of liquid distribution holes 109, the upper end of the guide tube 110 is higher than the first liquid distribution plate 107, and the lower end of the guide tube 110 is arranged through the second liquid distribution plate 108, and the material inlet on the upper head 102 extends between the first liquid distribution plate 107 and the second liquid distribution plate 108, and the hydrolyzate siloxane entering through the material inlet first enters the first liquid distribution plate 107 and the second liquid distribution plate 108. In the space between the plates 108, by means of the fluidity of the hydrolyzed siloxane, when the accumulated amount of the hydrolyzed siloxane reaches a certain level, the hydrolyzed siloxane will penetrate into the upper space of the first liquid distribution plate 107 from the liquid distribution holes 109. Since a number of liquid distribution holes 109 are evenly distributed on the first liquid distribution plate 107, it can be ensured that the hydrolyzed siloxane can be evenly distributed on the upper surface of the first liquid distribution plate 107. When the upper surface of the first liquid distribution plate 107 is covered with a certain height of hydrolyzed siloxane, hydrolyzed siloxane will enter each guide pipe 110 and flow to the lower space of the second liquid distribution plate 108, thereby achieving uniform distribution of the hydrolyzed siloxane in the dechlorination material 106. In order to better achieve the use effect of the hydrolyzed siloxane distribution, the upper end surface of the guide pipe 110 is set to an inclined surface structure, and the angle between the inclined surface and the upper surface of the first liquid distribution plate 107 is 45-55°.

[0014] Preferably, a glass fiber membrane 111 is attached to the upper surface of the flower plate 105. The glass fiber membrane 111 is used to prevent the loss of the dechlorination material 106. The glass fiber membrane 111 has good heat resistance, corrosion resistance, acid and alkali resistance, and has a good use effect.

[0015] Preferably, the upper head 102 is provided with a pressure relief valve and a pressure gauge, and the pressure gauge can monitor the working pressure in the tank body 101 in real time. When the working pressure in the tank body 101 is too high, the pressure relief valve can be used to release the pressure in time, thereby improving the safety of use. The tank body 101 is provided with a plurality of observation windows 112, through which the color change of the dechlorination material 106 can be observed in time, so as to understand whether the dechlorination material 106 is adsorbed saturated and needs to be replaced. The lower head 103 is provided with an anti-vortex plate 113 connected to the material outlet, and the anti-vortex plate 113 can slow down the scouring force of the hydrolyzate siloxane on the bottom of the lower head 103, thereby improving the use time.

[0016] Preferably, in order to ensure the dechlorination effect, a plurality of partition plates 114 are staggeredly installed up and down on the tank body 101 in the area of ​​the dechlorination material 106, and a plurality of micropores are evenly distributed on the partition plates 114. The upper surface of the partition plates 114 is arranged in an inclined surface structure. The partition plates 114 can play the role of loosening the dechlorination material 106, so that the hydrolyzed siloxane can also fully contact with the dechlorination material 106 in the middle area.

[0017] Preferably, the dechlorination material 106 in the first dechlorination device 1 and the second dechlorination device 5 is one of adsorption resin, activated carbon, dechlorination ball, and molecular sieve. The dechlorination material 106 in the third dechlorination device 10 is activated carbon. The adsorption resin and dechlorination ball in the dechlorination material 106 are preferably alkaline anion types, and the chloride ions in the hydrolyzate are removed by the ion exchange principle. The activated carbon and molecular sieve adsorb the chloride ions in the hydrolyzate by polar adsorption, thereby completing the dechlorination. The dechlorination material 106 in the first dechlorination device 1, the second dechlorination device 5 and the third dechlorination device 10 can be reasonably selected according to actual usage.

[0018] Furthermore, according to the requirements of use, the first dechlorination device 1, the second dechlorination device 5 and the third dechlorination device 10 are arranged to form at least two parallel structures. When one of the dechlorination devices needs to be repaired or the dechlorination material 106 needs to be replaced, the other dechlorination device can operate normally, and the continuous production of the system can be achieved without stopping.

Claims

1. A production system for low-chlorine siloxane and its linear form, comprising a raw material delivery pipe, characterized in that: The outlet end of the raw material conveying pipe is connected to a first dechlorination device (1), the material outlet of the first dechlorination device (1) is communicated with the material inlet of a primary heat exchanger (2), the material outlet of the primary heat exchanger (2) is connected to a light component removal tower (3), the top of the light component removal tower (3) is provided with a light component outlet, the material outlet at the bottom of the light component removal tower (3) is communicated with the material inlet of a secondary heat exchanger (4), the material outlet of the secondary heat exchanger (4) is connected to a second dechlorination device (5), and the second dechlorination device The material outlet of the third-stage heat exchanger (5) is connected to the material inlet of the third-stage heat exchanger (6), the material outlet of the third-stage heat exchanger (6) is connected to a loop separation tower (7), the top outlet of the loop separation tower (7) is connected to a loop body storage tank (8), the material outlet at the bottom of the loop separation tower (7) is connected to the material inlet of the fourth-stage heat exchanger (9), the material outlet of the fourth-stage heat exchanger (9) is connected to a third dechlorination device (10), and the material outlet of the third dechlorination device (10) is connected to a loop body storage tank (11).

2. The production system of a low-chlorine siloxane and its linear form according to claim 1, characterized in that: The first dechlorination device (1), the second dechlorination device (5) and the third dechlorination device (10) have the same structure, and all comprise a tank body (101) and an upper head (102) and a lower head (103) installed at both ends of the tank body (101); a heating jacket (104) is arranged at intervals on the outer side of the tank body (101); a medium inlet is arranged at the lower part of the heating jacket (104), and a medium outlet is arranged at the upper part; a liquid distribution assembly is arranged at the upper part of the tank body (101); two flower plates (105) are arranged at intervals at upper and lower parts of the tank body (101) below the liquid distribution assembly; the two flower plates (105) are filled with dechlorination material (106); a loading port is arranged on the tank body (101) above the dechlorination material (106); a discharging port is arranged on the tank body below the dechlorination material (106); and control valves are arranged on the loading port and the discharging port.

3. The production system of a low-chlorine siloxane and its linear form according to claim 2, characterized in that: The liquid distribution assembly comprises a first liquid distribution plate (107) and a second liquid distribution plate (108) which are arranged at an interval up and down; the first liquid distribution plate (107) is evenly processed with a plurality of liquid distribution holes (109); a plurality of guide pipes (110) are evenly installed on the first liquid distribution plate (107) between the plurality of liquid distribution holes (109); the upper ends of the guide pipes (110) are higher than the first liquid distribution plate (107); the lower ends of the guide pipes (110) are arranged to penetrate the second liquid distribution plate (108); and the material inlet on the upper head (102) extends between the first liquid distribution plate (107) and the second liquid distribution plate (108).

4. The production system of a low-chlorine siloxane and its linear form according to claim 3, characterized in that: The upper end surface of the flow guide tube (110) is arranged to be an inclined surface structure, and the angle between the inclined surface and the upper surface of the first liquid distribution plate (107) is 45-55 degrees.

5. The production system of a low-chlorine siloxane and its linear form according to claim 2, characterized in that: A glass fiber membrane (111) is pasted on the upper surface of the flower plate (105).

6. The production system of a low-chlorine siloxane and its linear form according to claim 2, characterized in that: The upper sealing head (102) is provided with a pressure relief valve and a pressure gauge, the tank body (101) is provided with a plurality of observation windows (112), and the lower sealing head (103) is provided with an anti-vortex plate (113) connected to the material outlet.

7. The production system of a low-chlorine siloxane and its linear form according to claim 2, characterized in that: A plurality of partition plates (114) are installed in an alternating manner up and down on the tank body (101) in the dechlorination material (106) area. A plurality of micropores are evenly distributed on the partition plates (114). The upper surface of the partition plates (114) is arranged in an inclined surface structure.

8. The production system of low-chlorine siloxane and its linear form according to claim 2, characterized in that: The dechlorination material (106) in the first dechlorination device (1) and the second dechlorination device (5) is one of adsorption resin, activated carbon, dechlorination balls, and molecular sieves, and the dechlorination material (106) in the third dechlorination device (10) is activated carbon.

9. The production system of low-chlorine siloxane and its linear form according to claim 1, characterized in that: The first dechlorination device (1), the second dechlorination device (5) and the third dechlorination device (10) are arranged in at least two parallel structures.

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