Process and system for producing low-chroma high-boiling silicone oil

Abstract

This invention relates to the field of silicone oil production technology, and discloses a production process and system for producing low-color, high-boiling silicone oil. The production system includes a hydrolysis reaction system, a hydrochloric acid cascade utilization system, an alkaline washing system, a dehydration system, and a hydrogen chloride treatment system connected to the hydrolysis reaction system, arranged sequentially. A dual-loop series hydrolysis process is adopted to make the hydrolysis reaction more thorough. Water resources are fully utilized and energy consumption is reduced by using dilute hydrochloric acid for reverse cascade concentration and reuse. Impurities in the high-boiling silicone oil are effectively removed by centrifugal extraction, water washing, and circulating alkaline washing. Finally, after static parallel dehydration combined with coalescence for deep dehydration, the high-boiling-point substances are efficiently hydrolyzed and the acid is recycled to obtain a finished high-boiling silicone oil with extremely low water content.

Description

Technical Field

[0001] This invention relates to the field of silicone oil production technology, and in particular to a production process and system for low-color, high-boiling silicone oil. Background Technology

[0002] Organosilicon high-boiling-point compounds are byproducts in the synthesis of methylchlorosilanes. Their main components are methylchloropolysilanes containing Si-Si and Si-C-Si bonds. High-boiling-point silicone oils can be prepared through hydrolysis, cracking, neutralization, and refining processes. They are widely used in defoaming, demolding, lubrication, and rubber and plastic processing.

[0003] The existing high-boiling-point silicone oil production process has the following shortcomings: (1) Some hydrolysis processes (such as CN116603471A) require the use of trimethylchlorosilane as a capping agent, which results in high raw material costs and thus high overall production costs of high-boiling silicone oil; (2) Some processes (such as CN109320721A) use vacuum distillation instead of water washing to remove acid, but the water trapped in the high-boiling silicone oil is difficult to completely remove, and some of the high-boiling silicone oil will escape with the vacuum system, affecting the purity and storage stability of the product. (3) Conventional hydrolysis processes result in high-boiling silicone oils with dark color due to problems such as many impurities in raw materials, uneven reaction, and incomplete deacidification, which limits their application in high-end transparent, electronic, and coating fields. (4) Direct discharge of dilute acid wastewater results in high acid consumption, high environmental pressure, and low resource utilization.

[0004] Therefore, it is necessary to develop a production process and system that can solve the problems of high cost, incomplete water removal, and dark product color of existing technologies. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a production process and system for low-color, high-boiling silicone oil.

[0006] To achieve this technical objective, the present invention adopts the following solution: In a first aspect, the present invention provides a low-color, high-boiling-point silicone oil production system, comprising a hydrolysis reaction system, a hydrochloric acid cascade utilization system, an alkaline washing system, a dehydration system, and a hydrogen chloride treatment system connected to the hydrolysis reaction system, arranged sequentially. The hydrolysis reaction system includes a first hydrolysis loop consisting of a first separator and a first hydrolysis reaction pump, and a second hydrolysis loop consisting of a second separator and a second hydrolysis reaction pump. The inlet of the first hydrolysis reaction pump is connected to a high-boiling-point inlet and a hydrochloric acid inlet. The outlet of the first hydrolysis reaction pump is connected to the top inlet of the first separator, and the bottom outlet of the first separator is connected to the inlet of the first hydrolysis reaction pump. The upper outlet of the first separator is connected to the inlet of the second separator, and the bottom outlet of the second separator is connected to the inlet of the second hydrolysis reaction pump. The outlet of the second hydrolysis reaction pump is connected to the hydrochloric acid inlet of the first hydrolysis reaction pump. The upper outlet of the second separator is connected to an acidic high-boiling-point silicone oil tank. A hydrogen chloride outlet is located at the top of both the first and second separators, and this outlet is connected to a hydrogen chloride treatment system via a hydrogen chloride pipeline. The hydrochloric acid cascade utilization system includes a first homogenizer connected to an acidic high-boiling silica oil tank; a first phase separator connected to the outlet of the first homogenizer; a second dilute hydrochloric acid buffer tank connected to the bottom outlet of the first phase separator; the second dilute hydrochloric acid buffer tank connected to the inlet of a second hydrolysis reaction pump; a second homogenizer connected to the top outlet of the first phase separator; a second phase separator connected to the second homogenizer; a first dilute hydrochloric acid buffer tank connected to the bottom outlet of the second phase separator; and a water washing extraction tower connected to the top outlet of the second phase separator. The oil phase outlet of the water washing extraction tower is connected to the mixer, the lower water phase inlet of the water washing extraction tower is connected to hot water, and the water phase outlet of the water washing extraction tower is connected to the inlet of the second homogenizer.

[0007] Furthermore, the bottom of the first and second layerers is a conical structure, and an insert-type layering heater is installed inside the conical structure of the first layerer; a distributor is installed at the top of the first layerer, the feed inlet of which extends into the interior of the first layerer, and an annular downward nozzle is provided, with 8 to 12 nozzles evenly arranged; the first hydrolysis reaction pump is provided with an exhaust pipeline, which is connected to the hydrogen chloride pipeline.

[0008] Furthermore, the alkaline washing system includes a third phase separator, a mixer, an alkaline pump, and an alkaline preparation tank; the outlet of the alkaline preparation tank is connected to the alkaline pump, the alkaline pump is connected to the mixer, the outlet of the mixer is connected to the third phase separator, the bottom outlet of the third phase separator is connected to the alkaline preparation tank, and the top outlet of the third phase separator is connected to the dewatering system; a concentration meter is installed inside the alkaline preparation tank.

[0009] Furthermore, the dewatering system includes a separation and settling tank, a coalescer, and a finished product tank. The inlet of the separation and settling tank is connected to the alkaline washing system, the outlet of the separation and settling tank is connected to the coalescer, and the coalescer is connected to the finished product tank.

[0010] Furthermore, 3 to 5 separation and settling tanks are arranged in parallel. The feed inlet of the separation and settling tank is located in the middle of the tank body, and a feed baffle is provided at the feed inlet. A distribution plate and right-angle packing are provided on the upper part of the separation and settling tank to promote water droplet aggregation.

[0011] Furthermore, the hydrogen chloride treatment system includes a hydrochloric acid circulating pump, a hydrogen chloride purification tower, a cyclone separator, a first adsorber, and a second adsorber. The hydrogen chloride purification tower is connected to the hydrogen chloride pipeline of the hydrolysis reaction system. The bottom outlet of the hydrogen chloride purification tower is connected to the hydrochloric acid circulating pump, and the outlet of the hydrochloric acid circulating pump is connected to the top inlet of the hydrogen chloride purification tower. Hydrogen chloride circulates and is purified in the loop formed by the hydrochloric acid circulating pump and the hydrogen chloride purification tower. The top outlet of the hydrogen chloride purification tower is connected to the cyclone separator, the cyclone separator is connected to the first adsorber, the first adsorber is connected to the second adsorber, and the second adsorber is connected to the subsequent process that needs to use hydrogen chloride or the hydrogen chloride storage tank.

[0012] Secondly, the present invention provides a process for producing low-color, high-boiling-point silicone oil using the aforementioned low-color, high-boiling-point silicone oil production system, comprising the following steps: Hydrolysis reaction: High-boiling-point substances and concentrated hydrochloric acid solution are pumped to the first hydrolysis reaction pump and then to the first separator. The separator heater heats the material to 60-70°C. The high-boiling-point substances react with the water in the concentrated hydrochloric acid solution. The unreacted high-boiling-point substances at the bottom of the first separator continue to circulate and react with hydrochloric acid in the first hydrolysis loop. The hydrogen chloride produced by hydrolysis is discharged from the hydrogen chloride outlet at the top of the first separator and enters the hydrogen chloride treatment system through the hydrogen chloride pipeline. During the reaction, high-boiling-point substances and concentrated hydrochloric acid solution are continuously replenished at the feed inlet of the first hydrolysis reaction pump. The high-boiling-point silicone oil that has been hydrolyzed in the first hydrolysis loop carries unreacted high-boiling-point substances into the second separator. It is circulated by the second hydrolysis reaction pump and continues to react in the second hydrolysis loop. The hydrogen chloride produced by hydrolysis is discharged from the hydrogen chloride outlet at the top of the second separator and enters the hydrogen chloride treatment system through the hydrogen chloride pipeline. During the reaction, 10% to 20% hydrochloric acid is added at the inlet of the second hydrolysis reaction pump. High-boiling-point silicone oil washing and hydrochloric acid cascade utilization: The hydrolysate from the second separator enters the acidic high-boiling-point silicone oil tank. The dilute hydrochloric acid, which has been separated by the first homogenizer, the first phase separator, and the water washing extraction tower, is mixed in the second homogenizer and then enters the second phase separator. After separation in the second phase separator, the hydrochloric acid enters the water washing extraction tower through the oil phase inlet at the bottom. Hot water enters the water washing extraction tower through the water phase inlet at the bottom. After mixing, the materials are separated by centrifugation. The dilute hydrochloric acid enters the second homogenizer, and the high-boiling-point silicone oil enters the mixer. High-boiling-point silicone oil alkaline washing: The high-boiling-point silicone oil from the water washing extraction tower and the alkaline solution from the alkaline solution preparation tank are mixed by a mixer and then enter the third phase separator. The alkaline solution at the bottom of the third phase separator flows back to the alkaline solution preparation tank, while the high-boiling-point silicone oil at the top is sent to the separation and settling tank by a feed pump. Settling and dehydration: The high-boiling-point silicone oil washed with alkali enters the separation and settling tank, and the crude siloxane separated by settling enters the coalescer for coalescence. The hydrolysate collected from the upper part of the coalescer enters the finished product tank. Hydrogen chloride purification: Hydrogen chloride gas from the hydrogen chloride pipeline of the hydrolysis reaction system enters the hydrogen chloride purification tower. After being sprayed and washed with saturated hydrochloric acid solution, the impurities entrained in the hydrogen chloride are reduced. The hydrogen chloride is then circulated and purified inside the hydrogen chloride purification tower by a hydrochloric acid circulation pump. The impurities are discharged through the bottom discharge port. The purified hydrogen chloride enters the cyclone separator for further purification. After being purified by the first and second adsorbers, it is sent to other processes for use or stored in the hydrogen chloride storage tank.

[0013] Further, the process of hydrochloric acid utilization is as follows: hot water enters the water washing extraction tower, then enters the second homogenizer, and after being separated by the second phase separator, it enters the first dilute hydrochloric acid buffer tank, then enters the first phase separator, and then enters the second dilute hydrochloric acid buffer tank; the second hydrolysis reaction pump gradually adds it to the second hydrolysis reaction loop. When the liquid level in the first hydrolysis reaction loop shows a downward trend, the concentrated hydrochloric acid from the second hydrolysis reaction loop is added to the first hydrolysis reaction loop.

[0014] The flow path of the aqueous phase is as follows: hot water → water washing extraction tower → second homogenizer → second phase separator → first dilute hydrochloric acid buffer tank → first homogenizer → first phase separator → second dilute hydrochloric acid buffer tank → second hydrolysis reaction loop → first hydrolysis reaction loop.

[0015] Furthermore, the alkali solution in the alkali preparation tank is a solution of sodium bicarbonate or sodium carbonate with a concentration of 2% to 10%. A concentration meter is installed in the alkali preparation tank, and sodium bicarbonate or sodium carbonate is added when the concentration falls below 2%.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention employs a dual-loop series hydrolysis process to ensure a more thorough hydrolysis reaction; it utilizes dilute hydrochloric acid for reverse-phase concentration and reuse to fully leverage water resources and reduce energy consumption; it effectively removes impurities from high-boiling silicone oil through centrifugal extraction, water washing, and circulating alkaline washing; and it further achieves efficient hydrolysis of high-boiling substances and recycling of acid solution through static parallel dehydration combined with deep dehydration by coalescence, ultimately yielding a high-boiling silicone oil product with low color and low moisture content. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of a low-color, high-boiling silicone oil production system in an embodiment of the present invention.

[0018] Figure 2 This is a schematic diagram of the hydrogen chloride treatment system in an embodiment of the present invention.

[0019] The diagram is labeled as follows: 1. First separator; 101. Separator heater; 102. Hydrogen chloride pipeline; 2. Second separator; 3. First hydrolysis reaction pump; 301. Exhaust pipeline; 4. Second hydrolysis reaction pump; 5. Acidic high-boiling silicone oil tank; 6. First dilute hydrochloric acid buffer tank; 7. First homogenizer; 8. First phase separator; 9. Second dilute hydrochloric acid buffer tank; 10. Second homogenizer; 11. Second phase separator; 12. Water washing extraction tower; 13. Third phase separator; 14. Mixer; 15. Alkali pump; 16. Alkali preparation tank; 17. Separation and settling tank; 18. Coalescer; 19. Finished product tank; 21. Hydrochloric acid circulation pump; 22. Hydrogen chloride impurity removal tower; 23. Cyclone impurity remover; 24. First adsorber; 25. Second adsorber. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0021] Unless otherwise specified, the experimental methods used in the embodiments and comparative examples of this invention are conventional methods. Unless otherwise specified, the materials and reagents used are commercially available.

[0022] See Figure 1 and Figure 2 The present invention provides a low-color, high-boiling silicone oil production system, including a hydrolysis reaction system, a hydrochloric acid cascade utilization system, an alkaline washing system, a dehydration system, and a hydrogen chloride treatment system.

[0023] The hydrolysis reaction system includes a first separator 1, a second separator 2, a first hydrolysis reaction pump 3, and a second hydrolysis reaction pump 4. The inlet of the first hydrolysis reaction pump 3 is connected to a high-boiling-point inlet and a hydrochloric acid inlet. The outlet of the first hydrolysis reaction pump 3 is connected to the top inlet of the first separator 1, and the bottom outlet of the first separator 1 is connected to the inlet of the first hydrolysis reaction pump 3. The first hydrolysis reaction pump 3 and the first separator 1 form a first hydrolysis loop. The upper outlet of the first separator 1 is connected to the upper inlet of the second separator 2, and the bottom outlet of the second separator 2 is connected to the inlet of the second hydrolysis reaction pump 4. The outlet of the second hydrolysis reaction pump 4 is connected to the inlet of the second separator 2. The second hydrolysis reaction pump 4 and the second separator 2 form a second hydrolysis loop. The outlet of the second hydrolysis reaction pump 4 is connected to the hydrochloric acid inlet of the first hydrolysis reaction pump 3. The upper outlet of the second separator 2 is connected to an acidic high-boiling-point silicone oil tank 5.

[0024] The bottoms of the first separator 1 and the second separator 2 are conical structures. An insert-type separator heater 101 is installed inside the conical structure of the first separator 1. The separator heater 101 is made of Hastelloy B3 material, characterized by low corrosion rate and rapid heating. A distributor is installed at the top of the first separator 1, with its inlet extending into the interior of the first separator 1, and it is equipped with annular downward-facing nozzles, with 8 to 12 nozzles evenly distributed. A hydrogen chloride outlet is located at the top of the first separator 1 and the second separator 2, and the hydrogen chloride outlet is connected to the hydrogen chloride treatment system via a hydrogen chloride pipeline 102.

[0025] The first hydrolysis reaction pump 3 is equipped with an exhaust pipe 301, which is connected to the hydrogen chloride pipeline 102. The first hydrolysis reaction pump 3 is a high-lift magnetically driven mixed-transfer pump, characterized by its low leakage rate and large flow rate of 20-100 m³ / h. 3 The pump boasts a flow rate of [number] / h and a head of up to 20m. The first hydrolysis reaction pump 3 promotes uniform contact between high-boiling-point substances and hydrochloric acid through high-flow circulation, resulting in a more complete reaction.

[0026] The hydrochloric acid cascade utilization system includes a first dilute hydrochloric acid buffer tank 6, a first homogenizer 7, a first phase separator 8, a second dilute hydrochloric acid buffer tank 9, a second homogenizer 10, a second phase separator 11, and a water washing extraction tower 12. The inlet of the first homogenizer 7 is connected to the acidic high-boiling silicone oil tank 5, the outlet of the first homogenizer 7 is connected to the inlet of the first phase separator 8, the bottom outlet of the first phase separator 8 is connected to the second dilute hydrochloric acid buffer tank 9, and the second dilute hydrochloric acid buffer tank 9 is connected to the inlet of the second hydrolysis reaction pump 4; the top outlet of the first phase separator 8 is connected to the second homogenizer 10, the second homogenizer 10 is connected to the inlet of the second phase separator 11, the bottom outlet of the second phase separator 11 is connected to the first dilute hydrochloric acid buffer tank 6, and the first dilute hydrochloric acid buffer tank 6 is connected to the inlet of the first homogenizer 7; the top outlet of the second phase separator 11 is connected to the lower oil phase inlet of the water washing extraction tower 12, the oil phase outlet of the water washing extraction tower 12 is connected to the mixer 14, the lower water phase inlet of the water washing extraction tower 12 is connected to hot water, and the water phase outlet of the water washing extraction tower 12 is connected to the inlet of the second homogenizer 10.

[0027] The process of hydrochloric acid utilization is as follows: Hot water (hydrochloric acid concentration 0%) enters the water washing extraction tower 12, and after passing through the water washing extraction tower 12 (hydrochloric acid concentration 1%~10%), it enters the second homogenizer 10. After being separated by the second phase separator 11, it enters the first dilute hydrochloric acid buffer tank 6, passes through the first homogenizer 7, enters the first phase separator 8 (hydrochloric acid concentration 10%~20%), and then enters the second dilute hydrochloric acid buffer tank 9. Hydrochloric acid (hydrochloric acid concentration 20%~35%) is gradually added to the second hydrolysis reaction loop by the second hydrolysis reaction pump 4. The first and second hydrolysis reaction loops are equipped with interface gauges to monitor the liquid level, and the control system maintains the set liquid level. Hydrochloric acid circulates and reacts in the second hydrolysis loop, and the concentration gradually increases to 35%~45%. When the liquid level in the first hydrolysis reaction loop shows a downward trend, hydrochloric acid from the second hydrolysis reaction loop is gradually added to the first hydrolysis reaction loop (hydrochloric acid concentration 45%) to keep the liquid level in the first hydrolysis loop constant. By using water for washing, the concentration of the water for washing is gradually increased to saturated hydrochloric acid. The flow path of the aqueous phase is as follows: Hot water → Water washing extraction tower → Second homogenizer → Second phase separator → First dilute hydrochloric acid buffer tank → First homogenizer → First phase separator → Second dilute hydrochloric acid buffer tank → Second hydrolysis reaction loop → First hydrolysis reaction loop.

[0028] The entire process follows the reverse circulation principle of "low concentration in, high concentration out," gradually increasing the concentration.

[0029] The first homogenizer 7 and the second homogenizer 10 are composed of rotors and stators. The rotors can be equipped with 1 to 3 rotors and different structural forms. The speed can be adjusted according to the actual use effect.

[0030] The working process of the water washing extraction tower 12 is as follows: high-boiling silicone oil enters from the lower oil phase inlet of the water washing extraction tower 12. After centrifugation, the heavy component dilute hydrochloric acid rises along the cylinder wall due to centrifugation and enters the heavy component collection chamber at the top of the cylinder. The dilute hydrochloric acid is discharged from the chamber along the pipeline. The high-boiling silicone oil is located close to the center of the centrifugal stirring shaft. After being collected from the top of the centrifugal chamber, the high-boiling silicone oil is discharged from the top and enters the mixer 14.

[0031] The alkaline washing system includes a third phase separator 13, a mixer 14, an alkaline pump 15, and an alkaline preparation tank 16. The outlet of the alkaline preparation tank 16 is connected to the alkaline pump 15, the alkaline pump 15 is connected to the mixer 14, the outlet of the mixer 14 is connected to the third phase separator 13, the bottom outlet of the third phase separator 13 is connected to the alkaline preparation tank 16, and the top outlet of the third phase separator 13 is connected to the separation and settling tank 17.

[0032] The alkali solution in the alkali preparation tank 16 is a solution of sodium bicarbonate or sodium carbonate with a concentration of 2% to 10%. The alkali preparation tank 16 is equipped with a concentration meter, and sodium bicarbonate or sodium carbonate is added when the concentration is lower than 2%.

[0033] The dewatering system includes a separation and settling tank 17, a coalescer 18, and a finished product tank 19. The inlet of the separation and settling tank 17 is connected to the third phase separator 13, the outlet of the separation and settling tank 17 is connected to the coalescer 18, and the coalescer 18 is connected to the finished product tank 19.

[0034] There are 3 to 5 separation and settling tanks 17 connected in parallel. The feed inlet of the separation and settling tank 17 is located in the middle of the tank body. A feed baffle is provided at the feed inlet so that the material can only move downwards while sticking to the baffle. A distribution plate and right-angle packing are provided on the upper part of the separation and settling tank 17 to promote the aggregation of water droplets.

[0035] The coalescer 18 contains a coalescing filter element and a separating filter element. These two elements work collaboratively, with the core principle being coalescing first and then separating, to jointly purify the high-boiling-point silicone oil by removing water and impurities. The coalescing filter element functions to demulsify, coalesce tiny droplets, and filter solid impurities. Utilizing hydrophilic multilayer fiber materials, the coalescing filter element adsorbs, collides, and merges tiny, emulsified water droplets (typically <10μm) in the oil into larger droplets (>50μm). Most of these larger droplets settle to the bottom of the coalescer 18 due to gravity and are discharged. The separating filter element completely intercepts the remaining water droplets, achieving final oil-water separation. The separating filter element uses hydrophobic and oleophilic materials (such as a Teflon / PTFE coating), allowing only oil molecules to pass through. Small water droplets that have not settled and are carried by the oil flow are completely blocked on the outer surface of the filter element.

[0036] The hydrogen chloride treatment system includes a hydrochloric acid circulating pump 21, a hydrogen chloride purification tower 22, a cyclone separator 23, a first adsorber 24, and a second adsorber 25. The hydrogen chloride purification tower 22 is connected to the hydrogen chloride pipeline 102 of the hydrolysis reaction system. The bottom outlet of the hydrogen chloride purification tower 22 is connected to the hydrochloric acid circulating pump 21, and the outlet of the hydrochloric acid circulating pump 21 is connected to the top inlet of the hydrogen chloride purification tower 22. Hydrogen chloride circulates and is purified in the loop formed by the hydrochloric acid circulating pump 21 and the hydrogen chloride purification tower 22. The top outlet of the hydrogen chloride purification tower 22 is connected to the cyclone separator 23, which is connected to the first adsorber 24. The first adsorber 24 is connected to the second adsorber 25, and the second adsorber 25 is connected to other processes requiring hydrogen chloride or hydrogen chloride storage tanks.

[0037] The top of the hydrogen chloride removal tower 22 is equipped with a spray nozzle, and the spray liquid is a saturated hydrochloric acid solution. The upper part of the hydrogen chloride removal tower 22 is equipped with packing for hydrochloric acid removal. The lower part of the hydrogen chloride removal tower 22 is also equipped with an observation hole and a discharge port.

[0038] The cyclone separator 23 has three chambers. In chamber ①, non-volatile silicone oil is added to the mark to reduce silicone oil impurities entrained in hydrogen chloride. In chamber ②, saturated hydrochloric acid is added to the mark to remove water-soluble inorganic impurities. In chamber ③, a baffle is provided to reduce water entrainment.

[0039] The production process using the aforementioned low-color, high-boiling silicone oil production system includes the following steps: Hydrolysis reaction: High-boiling-point substances and concentrated hydrochloric acid solution (saturated or near-saturated hydrochloric acid solution; for the initial reaction, saturated hydrochloric acid solution is added directly, followed by concentrated hydrochloric acid solution from subsequent systems) are pumped by the first hydrolysis reaction pump 3 to the first separator 1. The separator heater 101 heats the material to 60-70°C. The high-boiling-point substances react with water in the concentrated hydrochloric acid solution. Unreacted high-boiling-point substances at the bottom of the first separator 1 continue to circulate and react with hydrochloric acid in the first hydrolysis loop. The hydrogen chloride produced by hydrolysis is discharged from the hydrogen chloride outlet at the top of the first separator 1 and enters the hydrogen chloride treatment system through the hydrogen chloride pipeline 102. During the reaction, high-boiling-point substances and concentrated hydrochloric acid solution are continuously replenished at the inlet of the first hydrolysis reaction pump 3.

[0040] The high-boiling-point silicone oil that has been hydrolyzed in the first hydrolysis loop carries unreacted high-boiling-point substances into the second separator 2. It is then circulated by the second hydrolysis reaction pump 4 and continues to react in the second hydrolysis loop. The hydrogen chloride produced by hydrolysis is discharged from the hydrogen chloride outlet at the top of the second separator 2 and enters the hydrogen chloride treatment system through the hydrogen chloride pipeline 102. During the reaction, about 10% to 20% hydrochloric acid is added at the inlet of the second hydrolysis reaction pump 4.

[0041] High-boiling-point silicone oil washing and hydrochloric acid cascade utilization: The hydrolysate from the second separator 2 enters the acidic high-boiling-point silicone oil tank 5. The dilute hydrochloric acid, which is separated by the first homogenizer 7, the first phase separator 8, and the water washing extraction tower 12 in sequence, is mixed in the second homogenizer 10 and then enters the second phase separator 11. After separation in the second phase separator 11, it enters the water washing extraction tower 12 through the oil phase inlet at the bottom. Hot water enters the water washing extraction tower 12 through the water phase inlet at the bottom. After the materials are mixed, they are separated by centrifugation. The heavy component dilute hydrochloric acid rises along the cylinder wall due to centrifugation and enters the heavy component collection chamber at the top of the cylinder. The dilute hydrochloric acid is discharged from the chamber along the pipeline and enters the second homogenizer 10. The high-boiling-point silicone oil is close to the center of the centrifugal stirring shaft. It is collected from the top of the centrifugal chamber and discharged from the top, and then enters the mixer 14.

[0042] The process of hydrochloric acid utilization is as follows: Hot water (hydrochloric acid concentration 0%) enters the water washing extraction tower 12, and after passing through the water washing extraction tower 12 (hydrochloric acid concentration 1%~10%), it enters the second homogenizer 10. After being separated by the second phase separator 11, it enters the first dilute hydrochloric acid buffer tank 6, passes through the first homogenizer 7, enters the first phase separator 8 (hydrochloric acid concentration 10%~20%), and then enters the second dilute hydrochloric acid buffer tank 9. Hydrochloric acid (hydrochloric acid concentration 20%~35%) is gradually added to the second hydrolysis reaction loop via the second hydrolysis reaction pump 4. Interface gauges are installed in both the first and second hydrolysis reaction loops to control the liquid level. The hydrochloric acid circulates and reacts in the second hydrolysis loop, gradually increasing its concentration to 35%~45%. When the interface gauge of the first hydrolysis reaction loop shows a downward trend, the concentrated hydrochloric acid from the second hydrolysis reaction loop is added to the first hydrolysis reaction loop (hydrochloric acid concentration approximately 45%) to maintain a constant oleic acid interface in the first hydrolysis loop. The entire process follows the reverse circulation principle of "low concentration in, high concentration out," gradually increasing the concentration of the washing water to saturated hydrochloric acid. The flow path of the aqueous phase is as follows: Hot water → Water washing extraction tower → Second homogenizer → Second phase separator → First dilute hydrochloric acid buffer tank → First homogenizer → First phase separator → Second dilute hydrochloric acid buffer tank → Second hydrolysis reaction loop → First hydrolysis reaction loop.

[0043] High-boiling-point silicone oil alkaline washing: The high-boiling-point silicone oil from the water washing extraction tower 12 and the alkaline solution from the alkaline solution preparation tank 16 are mixed by the mixer 14 and then enter the third phase separator 13. The alkaline solution at the bottom of the third phase separator 13 flows back into the alkaline solution preparation tank 16, and the high-boiling-point silicone oil at the top is sent to the separation and settling tank 17 by the feed pump.

[0044] The alkali solution in the alkali preparation tank 16 is a solution of sodium bicarbonate or sodium carbonate with a concentration of 2% to 10%. The alkali preparation tank 16 is equipped with a concentration meter, and sodium bicarbonate or sodium carbonate is added when the concentration is less than 2%.

[0045] Dehydration by settling: The high-boiling-point silicone oil, after alkali washing, enters the settling tank 17. The material moves downward through the feed baffle and passes through the upper distribution plate and right-angle packing, feeding and discharging sequentially to extend the settling time and separate moisture. The crude siloxane separated by settling enters the coalescer 18 for coalescence. Using the coalescence filter element (hydrophilic material) and the separation filter element (hydrophobic material), tiny water droplets are coalesced and settled, ultimately yielding a finished high-boiling-point silicone oil with extremely low water content. The hydrolysate collected from the upper part of the coalescer 18 enters the finished product tank 19.

[0046] Hydrogen chloride purification: Hydrogen chloride gas from the hydrogen chloride pipeline 102 of the hydrolysis reaction system enters the hydrogen chloride impurity removal tower 22. After being sprayed and washed with saturated hydrochloric acid solution, the impurities entrained in the hydrogen chloride are reduced. The hydrogen chloride is then circulated and purified inside the hydrogen chloride impurity removal tower 22 by the hydrochloric acid circulation pump 21. The impurities are discharged through the bottom discharge port. The purified hydrogen chloride enters the cyclone separator 23 for further purification. After being purified by the first adsorber 24 and the second adsorber 25, it is sent to other processes for use or stored in the hydrogen chloride storage tank.

[0047] The cyclone separator 23 has three chambers. In chamber ①, non-volatile silicone oil is added to the mark to reduce silicone oil impurities entrained in hydrogen chloride. In chamber ②, saturated hydrochloric acid is added to the mark to remove water-soluble inorganic impurities. In chamber ③, a baffle is provided to reduce water entrainment.

[0048] When the hydrogen chloride treatment system is overpressurized (0.3 MPa), the hydrogen chloride is directly sent to the hydrogen chloride safety absorption device. The hydrogen chloride gas is absorbed by a two-stage falling film absorption tower and a tail gas absorption tower before being discharged into the hydrochloric acid tank to ensure production safety.

[0049] This invention employs a dual-loop series hydrolysis process to ensure a more thorough hydrolysis reaction. By using dilute hydrochloric acid for reverse-phase concentration and reuse, water resources are fully utilized, reducing energy consumption. Centrifugal extraction, water washing, and circulating alkali washing effectively remove impurities from the high-boiling silicone oil. Further static parallel dehydration combined with coalescence and deep dehydration ultimately achieves efficient hydrolysis of the high-boiling substance and acid recycling, resulting in a high-boiling silicone oil product with low color and low moisture content (tested to be below 100 ppm).

[0050] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; if these modifications and variations fall within the scope of the claims of the present invention and their equivalents, they should all be considered to be within the protection scope of the present invention.

Claims

1. A low-color, high-boiling-point silicone oil production system, comprising, in sequence, a hydrolysis reaction system, a hydrochloric acid cascade utilization system, an alkaline washing system, a dehydration system, and a hydrogen chloride treatment system connected to the hydrolysis reaction system, characterized in that, The hydrolysis reaction system includes a first hydrolysis loop consisting of a first separator (1) and a first hydrolysis reaction pump (3), and a second hydrolysis loop consisting of a second separator (2) and a second hydrolysis reaction pump (4). The inlet of the first hydrolysis reaction pump (3) is connected to a high-boiling-point inlet and a hydrochloric acid inlet. The outlet of the first hydrolysis reaction pump (3) is connected to the top inlet of the first separator (1), and the bottom outlet of the first separator (1) is connected to the inlet of the first hydrolysis reaction pump (3). The upper outlet of the first separator (1) is connected to the inlet of the second separator (2), and the bottom outlet of the second separator (2) is connected to the inlet of the second hydrolysis reaction pump (4). The outlet of the second hydrolysis reaction pump (4) is connected to the inlet of the second separator (2). The outlet of the second hydrolysis reaction pump (4) is connected to the hydrochloric acid inlet of the first hydrolysis reaction pump (3). The upper outlet of the second separator (2) is connected to an acidic high-boiling silicone oil tank (5); the top of the first separator (1) and the second separator (2) are provided with hydrogen chloride outlets, which are connected to the hydrogen chloride treatment system through a hydrogen chloride pipeline (102). The hydrochloric acid cascade utilization system includes a first homogenizer (7) connected to an acidic high-boiling silica oil tank (5), a first phase separator (8) connected to the outlet of the first homogenizer (7), a second dilute hydrochloric acid buffer tank (9) connected to the bottom outlet of the first phase separator (8), and the second dilute hydrochloric acid buffer tank (9) connected to the inlet of a second hydrolysis reaction pump (4); a second homogenizer (10) connected to the top outlet of the first phase separator (8), and a second phase separator (1... 1) The bottom outlet of the second phase separator (11) is connected to the first dilute hydrochloric acid buffer tank (6), and the first dilute hydrochloric acid buffer tank (6) is connected to the inlet of the first homogenizer (7); the top outlet of the second phase separator (11) is connected to the water washing extraction tower (12), the oil phase outlet of the water washing extraction tower (12) is connected to the mixer (14), the lower water phase inlet of the water washing extraction tower (12) is connected to hot water, and the water phase outlet of the water washing extraction tower (12) is connected to the inlet of the second homogenizer (10).

2. The low color high-boiling silicone oil production system according to claim 1, wherein The bottom of the first layerer (1) and the second layerer (2) is a conical structure. An insert-type layerer heater (101) is installed inside the conical structure of the first layerer (1). A distributor is installed on the upper part of the first layerer (1), and its feed inlet extends into the interior of the first layerer (1). It is also equipped with annular downward nozzles, with 8 to 12 nozzles evenly arranged. The first hydrolysis reaction pump (3) is equipped with an exhaust pipe (301), which is connected to the hydrogen chloride pipeline (102).

3. The low color high-boiling silicone oil production system according to claim 1, characterized by, The alkaline washing system includes a third phase separator (13), a mixer (14), an alkaline pump (15), and an alkaline preparation tank (16). The outlet of the alkaline preparation tank (16) is connected to the alkaline pump (15), the alkaline pump (15) is connected to the mixer (14), the outlet of the mixer (14) is connected to the third phase separator (13), the bottom outlet of the third phase separator (13) is connected to the alkaline preparation tank (16), and the top outlet of the third phase separator (13) is connected to the dewatering system. A concentration meter is installed in the alkaline preparation tank (16).

4. The low color high-boiling silicone oil production system according to claim 1, wherein The dewatering system includes a separation and settling tank (17), a coalescer (18), and a finished product tank (19). The inlet of the separation and settling tank (17) is connected to the alkaline washing system, the outlet of the separation and settling tank (17) is connected to the coalescer (18), and the coalescer (18) is connected to the finished product tank (19).

5. The low color high-boiling silicone oil production system according to claim 4, wherein There are 3 to 5 separation and settling tanks (17) connected in parallel. The feed inlet of the separation and settling tank (17) is located in the middle of the tank body. A feed baffle is provided at the feed inlet. A distribution plate and right-angle packing are provided on the upper part of the separation and settling tank (17) to promote the aggregation of water droplets.

6. The low-color, high-boiling-point silicone oil production system according to claim 1, characterized in that, The hydrogen chloride treatment system includes a hydrochloric acid circulating pump (21), a hydrogen chloride purification tower (22), a cyclone separator (23), a first adsorber (24), and a second adsorber (25). The hydrogen chloride purification tower (22) is connected to the hydrogen chloride pipeline (102) of the hydrolysis reaction system. The bottom outlet of the hydrogen chloride purification tower (22) is connected to the hydrochloric acid circulating pump (21), and the outlet of the hydrochloric acid circulating pump (21) is connected to the top inlet of the hydrogen chloride purification tower (22). The hydrogen chloride is circulated and purified in the loop formed by the hydrochloric acid circulating pump (21) and the hydrogen chloride purification tower (22). The top outlet of the hydrogen chloride purification tower (22) is connected to the cyclone separator (23), the cyclone separator (23) is connected to the first adsorber (24), and the first adsorber (24) is connected to the second adsorber (25).

7. A process for producing low-color, high-boiling-point silicone oil using the low-color, high-boiling-point silicone oil production system according to any one of claims 1-6, characterized in that, Includes the following steps: Hydrolysis reaction: High-boiling-point substances and concentrated hydrochloric acid solution are transported to the first layerer (1) via the first hydrolysis reaction pump (3). The layer heater (101) heats the material to 60~70℃. The high-boiling-point substances react with the water in the concentrated hydrochloric acid solution. The unreacted high-boiling-point substances at the bottom of the first layerer (1) continue to circulate and react with hydrochloric acid in the first hydrolysis loop. The hydrogen chloride produced by hydrolysis is discharged from the hydrogen chloride outlet at the top of the first layerer (1) and enters the hydrogen chloride treatment system through the hydrogen chloride pipeline (102). During the reaction, high-boiling-point substances and concentrated hydrochloric acid solution are continuously replenished at the feed inlet of the first hydrolysis reaction pump (3). The high-boiling-point silicone oil that has been hydrolyzed in the first hydrolysis loop carries unreacted high-boiling-point substances into the second separator (2). It is circulated by the second hydrolysis reaction pump (4) and continues to react in the second hydrolysis loop. The hydrogen chloride produced by hydrolysis is discharged from the hydrogen chloride outlet at the top of the second separator (2) and enters the hydrogen chloride treatment system through the hydrogen chloride pipeline (102). During the reaction, 10%~20% hydrochloric acid is added at the feed inlet of the second hydrolysis reaction pump (4). High-boiling-point silicone oil washing and hydrochloric acid cascade utilization: The hydrolysate from the second separator (2) enters the acidic high-boiling-point silicone oil tank (5). The dilute hydrochloric acid, which is separated by the first homogenizer (7), the first phase separator (8), and the water washing extraction tower (12) in sequence, is mixed in the second homogenizer (10) and then enters the second phase separator (11). After separation by the second phase separator (11), it enters the water washing extraction tower (12) through the bottom oil phase inlet. Hot water enters the water washing extraction tower (12) through the lower water phase inlet. After the materials are mixed, they are separated by centrifugation. The dilute hydrochloric acid enters the second homogenizer (10), and the high-boiling-point silicone oil enters the mixer (14). High-boiling-point silicone oil alkaline washing: The high-boiling-point silicone oil from the water washing extraction tower (12) and the alkaline solution from the alkaline solution preparation tank (16) are mixed by the mixer (14) and then enter the third phase separator (13). The alkaline solution at the bottom of the third phase separator (13) flows back into the alkaline solution preparation tank (16), and the high-boiling-point silicone oil at the top is sent to the separation and settling tank (17) by the feed pump. Settling and dehydration: The high-boiling silicone oil washed with alkali enters the separation and settling tank (17), and the crude siloxane separated by settling enters the coalescer (18) for coalescence. The hydrolysate collected from the upper part of the coalescer (18) enters the finished product tank (19). Hydrogen chloride purification: Hydrogen chloride gas from the hydrogen chloride pipeline (102) of the hydrolysis reaction system enters the hydrogen chloride impurity removal tower (22), and is rinsed by spraying with saturated hydrochloric acid solution to reduce the impurities carried in the hydrogen chloride. It is then circulated and purified inside the hydrogen chloride impurity removal tower (22) by the hydrochloric acid circulation pump (21). The impurities are discharged through the bottom discharge port. The purified hydrogen chloride enters the cyclone separator (23) for further purification, and is then purified by the first adsorber (24) and the second adsorber (25) before being sent to other processes for use or stored in the hydrogen chloride storage tank.

8. The low-color, high-boiling-point silicone oil production process according to claim 7, characterized in that, The process of hydrochloric acid utilization: hot water enters the water washing extraction tower (12), and after passing through the water washing extraction tower (12), it enters the second homogenizer (10), and after being separated by the second phase separator (11), it enters the first dilute hydrochloric acid buffer tank (6), and after passing through the first homogenizer (7), it enters the first phase separator (8), and then enters the second dilute hydrochloric acid buffer tank (9); the second hydrolysis reaction pump (4) gradually adds it to the second hydrolysis reaction loop. When the liquid level of the first hydrolysis reaction loop shows a downward trend, the hydrochloric acid concentrated in the second hydrolysis reaction loop is added to the first hydrolysis reaction loop.

9. The low-color, high-boiling-point silicone oil production process according to claim 7, characterized in that, The alkaline solution in the alkaline solution preparation tank (16) is a solution of sodium bicarbonate or sodium carbonate with a concentration of 2% to 10%.

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