A recovery device for tetramethyldihydrodisiloxane

Abstract

The utility model discloses a kind of recovery devices of tetramethyldihydrodisiloxane, including packing rectification tower, first heat exchanger, first material tank, purification pipe, second heat exchanger and second material tank;The packing rectification tower top is sequentially connected with first heat exchanger and first material tank, and the product tetramethyldihydrodisiloxane of rectification is obtained;The packing rectification tower bottom side outlet is connected with purification pipe, and purification pipe is sequentially connected with second heat exchanger and second material tank, short-path distillation is carried out to low-boiling-point compound in tower bottom, and the recovery of tetramethyldihydrodisiloxane is realized.The device can efficiently recover tetramethyldihydrodisiloxane remaining in column still residual liquid in rectification, improve the total yield of tetramethyldihydrodisiloxane.

Description

Technical Field

[0001] This utility model relates to the field of organosilicon technology, specifically to a device for recovering tetramethyldihydrodisiloxane. Background Technology

[0002] In the production of tetramethyldihydrodisiloxane, the product obtained is a crude product containing many impurities, which usually requires purification through distillation. Current technology involves hydrolyzing low-boiling methylchlorosilanes (the main component of which is dimethylhydrochlorosilane) to obtain low-boiling hydrolyzed oil. This low-boiling hydrolyzed oil is then purified by distillation to obtain qualified tetramethyldihydrodisiloxane with the required purity.

[0003] CN 205516579 U discloses a multifunctional production apparatus for tetramethyldihydrodisiloxane, including a heating furnace, a distillation column, a condenser, and a spraying device. The distillation column is installed above the heating furnace and is connected to the condenser and the spraying device. The apparatus also includes a triangular iron frame, a rotary motor, a high-level tank, and a feed pump. The rotary motor is connected to the triangular iron frame, which has a rotating pin connected to a fixing ring. The fixing ring is connected to the distillation column, which is connected to a control valve. The control valve is connected to the high-level tank, which is connected to the feed pump. This invention solves the problem of uneven heating during distillation and allows for both conventional continuous distillation experiments and continuous extractive distillation and continuous reactive distillation experiments without increasing investment.

[0004] CN215049792U discloses a system for recovering and utilizing a tetramethylsiloxane mixture, comprising: a distillation unit for receiving and distilling a tetramethylsiloxane mixture; a disproportionation reaction unit connected to the distillation unit for receiving high-boiling-point residues and tetramethylsilane fractions from the distillation column, wherein the high-boiling-point residues and tetramethylsilane fractions are disproportionated in the disproportionation reaction unit; a hydrolysis distillation unit connected to the distillation unit for receiving a dimethylchlorosilane fraction and hydrolyzing the dimethylchlorosilane fraction in the hydrolysis distillation unit to obtain a hydrogen-containing dual-end product; and a polymerization de-lowering unit connected to the hydrolysis distillation unit for receiving the hydrogen-containing dual-end product and polymerizing and de-lowering the hydrogen-containing dual-end product in the polymerization de-lowering unit to generate end-hydrogen-containing silicone oil.

[0005] However, after the distillation of hydrolyzed oil, approximately 10% to 15% tetramethyldihydrodisiloxane (THD) remains in the column packing within the distillation column, forming internal reflux. This prevents it from distilling upwards, and when the steam in the column stops, the THD falls back into the column, causing excessive levels of THD in the high-boiling-point silicone oil. Since THD is an extremely flammable and volatile substance, its residue in the high-boiling-point silicone oil poses a safety hazard for its application, significantly reduces its solids content, and hinders its further use. Utility Model Content

[0006] To address the issue of residual target product in the distillation residue after hydrolysis of tetramethyldihydrodisiloxane, this invention provides a tetramethyldihydrodisiloxane recovery device. This device can efficiently recover tetramethyldihydrodisiloxane remaining in the distillation residue, thereby increasing the overall yield of tetramethyldihydrodisiloxane.

[0007] To achieve the above objectives, the technical solution adopted by this utility model is as follows: A device for recovering tetramethyldihydrodisiloxane includes a packed distillation column, a first heat exchanger, a first material tank, a purification tube, a second heat exchanger, and a second material tank. The top of the packed distillation column is connected in sequence to a first heat exchanger and a first material tank to obtain the distillation product tetramethyldihydrodisiloxane. The packing distillation column has a purification pipe connected to the bottom outlet, which is then connected to a second heat exchanger and a second material tank. This allows for short-path distillation of the low-boiling-point compounds at the bottom of the column, thereby recovering tetramethyldihydrodisiloxane.

[0008] In the purification process of tetramethyldihydrodisiloxane, hydrolysis yields low-boiling hydrolyzed oil, which is then distilled to obtain tetramethyldihydrodisiloxane with the required purity. However, approximately 10% to 15% of the target product is difficult to distill off and remains at the bottom of the distillation column, reducing yield and causing a decline in the quality of the high-boiling silicone oil byproduct at the bottom of the column. This invention introduces a purification tube at the bottom of the distillation column, using an ultra-short-path distillation method to distill, purify, and recover this 8% to 12% target product. This significantly improves the yield of tetramethyldihydrodisiloxane, reduces the tetramethyldihydrodisiloxane content in the high-boiling silicone oil, lowers the risk, and enhances the overall economic efficiency of the system.

[0009] The purification tube is a short-path distillation gas phase tube equipped with stainless steel packing.

[0010] Preferably, the straight section of the purification tube is not less than 1 meter in length, and the effective height facilitates the effective distillation of the target product, resulting in a higher purity of the recovered product.

[0011] The straight section of the purification tube is filled with metal stepped ring packing, and the upper part is filled with pressure ring fixing packing.

[0012] The purification tube is topped with a straight pipe with a slope of 5-15%, and the outlet of the straight pipe is connected to a second heat exchanger. This prevents the purified tetramethyldihydrodisiloxane from flowing back into the packed distillation column, thus improving the recovery rate.

[0013] The bottom of the first heat exchanger is equipped with a pipe that connects to a packed distillation column.

[0014] Compared with the prior art, the present invention has the following beneficial effects: In this invention, an ultra-short-path distillation purification tube is added to the bottom of the distillation column to recover tetramethyldihydrodisiloxane, which can significantly improve the yield of tetramethyldihydrodisiloxane, reduce the content of tetramethyldihydrodisiloxane in high-boiling silicone oil, reduce the risk, and improve the overall economic benefits of the system. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of a traditional tetramethyldihydrodisiloxane distillation apparatus.

[0016] Figure 2 This is a schematic diagram of the tetramethyldihydrodisiloxane distillation and recovery device of this utility model. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this utility model clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this utility model. Modifications or equivalent substitutions made by those skilled in the art based on their understanding of the technical solutions of this utility model, without departing from the spirit and scope of the technical solutions of this utility model, should all be covered within the protection scope of this utility model.

[0018] Comparative Example 1 A schematic diagram of a traditional tetramethyldihydrodisiloxane recovery device is shown below. Figure 1 As shown, it includes a packed distillation column 1, a first heat exchanger 2, and a first material tank 3. The top of the packed distillation column 1 is connected to the first heat exchanger 2 and the first material tank 3 in sequence to obtain the distillation product tetramethyldihydrodisiloxane. With an input of 532 kg, a distillation column pressure of 15 kPa, a top temperature of 75-85℃, and a bottom temperature of 135-145℃, 316 kg of tetramethyldihydrodisiloxane was obtained, with a distillation yield of 59.39%. The high-boiling-point silicone oil at the bottom of the distillation column contained 10%-15% tetramethyldihydrodisiloxane.

[0019] Example 1 A schematic diagram of a tetramethyldihydrodisiloxane recovery device according to the present invention is shown below. Figure 2 As shown, it includes a packed distillation column 1, a first heat exchanger 2, a first material tank 3, a purification tube 4, a second heat exchanger 5, and a second material tank 6; The top of the packed distillation column 1 is connected to the first heat exchanger 2 and the first material tank 3 in sequence to obtain the distillation product tetramethyldihydrodisiloxane; the bottom outlet of the packed distillation column 1 is connected to the purification pipe 4, which is connected to the second heat exchanger 5 and the second material tank 6 in sequence to perform short-path distillation of the low-boiling-point compound at the bottom of the column to realize the recovery of tetramethyldihydrodisiloxane.

[0020] Purification tube 4 is a short-path distillation vapor phase tube with stainless steel packing. It is a DN100 pipe with a straight section of 1500mm in length. The straight section is filled with stepped ring bulk packing, and the upper part is fixed with a pressure ring to secure the stainless steel packing. The outlet has a 1200mm straight pipe with a 10% slope, and the outlet of the straight pipe is connected to the second heat exchanger.

[0021] With an input of 532 kg, a distillation column pressure of 15 kPa, a top temperature of 75-85℃, and a bottom temperature of 135-145℃, 339.89 kg of tetramethyldihydrodisiloxane was obtained, with a distillation yield of 63.89%. The tetramethyldihydrodisiloxane content in the high-boiling-point silicone oil at the bottom of the distillation column was less than 2%.

[0022] By using this method, the total yield of tetramethyldihydrodisiloxane is increased by 4.5% per batch of hydrolyzed oil, resulting in improved profitability. The content of the target product tetramethyldihydrodisiloxane in the high-boiling silicone oil in the reboiler is reduced to below 2%, and the product can also be used after the tetramethyldihydrodisiloxane content in the high-boiling silicone oil is reduced.

Claims

1. A recovery apparatus of tetramethyldihydrodisiloxane, characterized by comprising: It includes a packed distillation column, a first heat exchanger, a first material tank, a purification pipe, a second heat exchanger, and a second material tank; The top of the packed distillation column is connected in sequence to a first heat exchanger and a first material tank to obtain the distillation product tetramethyldihydrodisiloxane. The packing distillation column has a purification pipe connected to the bottom outlet, which is then connected to a second heat exchanger and a second material tank. This allows for short-path distillation of the low-boiling-point compounds at the bottom of the column, thereby recovering tetramethyldihydrodisiloxane.

2. The recovery apparatus of tetramethyldisiloxane according to claim 1, characterized by The purification tube is a short-path distillation gas phase tube equipped with stainless steel packing.

3. The tetramethyldihydrodisiloxane recovery device according to claim 1, characterized in that, The straight section of the purification tube shall be no less than 1 meter in length.

4. The recovery apparatus of tetramethyldisiloxane according to claim 1, characterized by The straight section of the purification tube is filled with stepped ring bulk packing, and the upper part is filled with pressure ring fixed packing.

5. The tetramethyldihydrodisiloxane recovery device according to claim 1, characterized in that, The top of the purification tube is equipped with a straight pipe with a slope of 5 to 15%, and the outlet of the straight pipe is connected to the second heat exchanger.

6. The tetramethyldihydrodisiloxane recovery device according to claim 1, characterized in that, The bottom of the first heat exchanger is equipped with a pipe that connects to a packed distillation column.

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