A high-efficiency recovery system of chloromethane in non-condensable gas for silicone production
Patent Information
- Application Number
- CN202522330291.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-03
- Publication Date
- 2026-10-09
- Estimated Expiration
- 2035-11-03
AI Technical Summary
[0002]有机硅单体合成过程中，利用氯甲烷与硅粉反应生产甲基氯硅烷，但由于技术的限制，氯甲烷的一次转化率只能达到45%～50%，再加上氯甲烷往往还会过量添加，反应完毕后，会有大量未反应的氯甲烷和反应过程中产生的甲烷、异丁烷、异丁烯等烷烃烯烃轻组分需通过精馏塔分离回收使用，在分离过程中，氮气、甲烷等不凝气会带走一部分氯甲烷，导致氯甲烷消耗的增高，生产成本的增加
[0011]本实用新型用于对氮气、甲烷等不凝气中的氯甲烷进行回收，运行时，将从粗单体塔采出的混合粗单体经过泵加压后，分别送入液液预冷器和气液预冷器进行预冷，然后通入深冷器，利用-35℃氟利昂R507，进一步将混合粗单体的温度降至-25℃～-30℃，然后将混合粗单体送入吸收塔的上部，同时，从吸收塔下部的进气管通入不凝气，不凝气与混合粗单体逆向接触，利用低温环境下混合粗单体的选择性吸收特性，即：氯甲烷气体在粗单体液体中具有良好的溶解度，而异丁烷、异丁烯等烷烃烯烃在粗单体液体中的溶解度较低，这样不凝气中的氯甲烷就会被混合粗单体吸收，而剩余的其余不凝气则从吸收塔顶部的排气口排出，克服了烷烃烯烃等杂质不断富集的问题，达到回收不凝气中氯甲烷的目的。在本实用新型中，相比于传统的采用膜吸收法、变压吸附法等方法回收氯甲烷来说，通过对冷凝吸收过程温度和压力的控制，洗涤回收后的氯甲烷中的烷烃烯烃等有害杂质含量大幅降低，回收的氯甲烷质量可维持在95%以上，将其返回流化床反应器后，有效提高流化床反应器的正常运行周期，提高系统产物的产量和质量；其次，在本实用新型中，液液预冷器中的冷却介质为吸收塔排出的富含氯甲烷的混合粗单体，这部分混合粗单体的温度较低，可吸收从粗单体塔中排出的混合粗单体中的热量，达到混合粗单体预冷的目的，同时，气液预冷器中的冷却介质为吸收塔排出的经过分离氯甲烷的不凝气，这部分不凝气的温度同样较低，可吸收从粗单体塔中排出的混合粗单体中的热量，达到混合粗单体预冷的目的，减少了后续深冷器的运行负荷，减少了氟利昂的使用量，具有节能降耗的作用。综上所述，本实用新型具有能克服杂质富集，回收质量高，能延长系统稳定运行周期的优点。
Smart Images
Figure CN224822113U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the technical field of equipment for recovering chloromethane from non-condensable gases, specifically to a high-efficiency system for recovering chloromethane from non-condensable gases used in organosilicon production. Background Technology
[0002] In the synthesis of organosilicon monomers, chloromethane is reacted with silicon powder to produce methylchlorosilane. However, due to technological limitations, the conversion rate of chloromethane in a single reaction can only reach 45% to 50%. In addition, chloromethane is often added in excess. After the reaction is completed, a large amount of unreacted chloromethane and light components such as methane, isobutane, and isobutene produced during the reaction need to be separated and recovered by a distillation column. During the separation process, non-condensable gases such as nitrogen and methane will carry away some of the chloromethane, leading to increased chloromethane consumption and increased production costs.
[0003] Currently, the industry generally uses methods such as membrane absorption and pressure swing adsorption to recover the chloromethane carried away with non-condensable gases. However, the recovered chloromethane contains a certain amount of hydrocarbons such as isobutane and isobutylene. When the chloromethane is returned to the fluidized bed for further reaction, these hydrocarbons decompose and form carbon deposits on the inlet distribution plate and tube bundle of the fluidized bed. This causes problems such as clogging of the distribution holes, reduced heat exchange efficiency of the tube bundle, and decreased activity of silicon powder and catalyst, leading to a decrease in system output, an increase in by-product content, and a shortened operating cycle of the fluidized bed reactor. It also necessitates shutdown, maintenance, and cleaning of the internal components of the fluidized bed reactor. In summary, in traditional chloromethane recovery processes from non-condensable gases, the alkane and olefin impurities in the chloromethane are not effectively separated and removed. This results in the continuous enrichment and increasing content of alkane and olefins such as isobutane and isobutylene during the recovery process, leading to low-quality recovered chloromethane and affecting the stable operation of the subsequent fluidized bed. Therefore, it is objectively necessary to develop a high-efficiency recovery system for chloromethane in non-condensable gases used in organosilicon production that can overcome impurity enrichment, achieve high recovery quality, and extend the stable operation cycle of the system. Utility Model Content
[0004] The purpose of this invention is to provide a highly efficient recovery system for chloromethane in non-condensable gases used in organosilicon production that can overcome impurity enrichment, achieve high recovery quality, and extend the stable operation cycle of the system.
[0005] The purpose of this utility model is achieved as follows: it includes an absorption tower and a cooler. The top of the absorption tower is provided with an exhaust port, the bottom of the absorption tower is provided with an inlet pipe, and the bottom of the absorption tower is provided with a drain port. The cooler includes a liquid-liquid precooler, a gas-liquid precooler, and a cryocooler. The drain port is connected to the shell-side inlet of the liquid-liquid precooler through a pipeline. The tube-side outlet of the liquid-liquid precooler is connected to the tube-side inlet of the cryocooler through a pipeline. The tube-side outlet of the cryocooler is connected to the upper part of the absorption tower through a pipeline. The exhaust port is connected to the shell-side inlet of the gas-liquid precooler through a pipeline. The tube-side outlet of the gas-liquid precooler is connected to the tube-side inlet of the cryocooler through a pipeline. The tube-side inlets of both the gas-liquid precooler and the liquid-liquid precooler are connected to the coarse single-unit tower.
[0006] Furthermore, the absorption tower is equipped with spray components and multiple packing layers from top to bottom.
[0007] Furthermore, an air-to-air mixer is installed on the intake pipe, and the exhaust port is connected to the air-to-air mixer through a return pipe.
[0008] Furthermore, an air-to-air precooler is installed on the outside of the absorption tower. The inlet pipe is connected to the tube-side inlet of the air-to-air precooler, the tube-side outlet of the air-to-air precooler is connected to the non-condensable gas inlet on the absorption tower, and the exhaust port is connected to the shell-side inlet of the air-to-air precooler through a split pipe.
[0009] Furthermore, the shell-side outlet of the cryogenic unit is connected to a gas-liquid separator via a pipeline, and the drain port of the gas-liquid separator is connected to the top of the shell-side of the cryogenic unit.
[0010] Furthermore, a liquid-liquid mixer is installed on the inlet line of the cryogenic tube side, and the outlet lines of both the liquid-liquid precooler and the gas-liquid precooler are connected to the liquid-liquid mixer.
[0011] This invention is used to recover chloromethane from non-condensable gases such as nitrogen and methane. During operation, the mixed crude monomers collected from the crude monomer tower are pressurized by a pump and then sent to a liquid-liquid precooler and a gas-liquid precooler for precooling. Then, they are introduced into a cryogenic chamber, where -35℃ Freon R507 is used to further reduce the temperature of the mixed crude monomers to -25℃ to -30℃. The mixed crude monomers are then sent to the upper part of the absorption tower. At the same time, non-condensable gas is introduced from the inlet pipe at the bottom of the absorption tower. The non-condensable gas comes into countercurrent contact with the mixed crude monomers. Taking advantage of the selective absorption characteristics of the mixed crude monomers under low temperature conditions, namely, chloromethane gas has good solubility in the crude monomer liquid, while isobutane, isobutene, and other alkanes and alkenes have low solubility in the crude monomer liquid, the chloromethane in the non-condensable gas is absorbed by the mixed crude monomers. The remaining non-condensable gas is discharged from the exhaust port at the top of the absorption tower, overcoming the problem of continuous enrichment of impurities such as alkanes and alkenes, and achieving the purpose of recovering chloromethane from the non-condensable gas. In this invention, compared to traditional methods such as membrane absorption and pressure swing adsorption for recovering chloromethane, the content of harmful impurities such as alkanes and olefins in the washed and recovered chloromethane is significantly reduced by controlling the temperature and pressure during the condensation absorption process. The quality of the recovered chloromethane can be maintained at over 95%, and its return to the fluidized bed reactor effectively improves the normal operating cycle of the fluidized bed reactor and increases the yield and quality of the system products. Secondly, in this invention, the cooling medium in the liquid-liquid precooler is the mixed crude monomer rich in chloromethane discharged from the absorption tower. This mixed crude monomer has a low temperature and can absorb the heat from the mixed crude monomer discharged from the crude monomer tower, achieving the purpose of precooling the mixed crude monomer. At the same time, the cooling medium in the gas-liquid precooler is the non-condensable gas discharged from the absorption tower after chloromethane separation. This non-condensable gas also has a low temperature and can absorb the heat from the mixed crude monomer discharged from the crude monomer tower, achieving the purpose of precooling the mixed crude monomer. This reduces the operating load of the subsequent cryogenic reactor and reduces the amount of Freon used, thus achieving energy saving and consumption reduction. In summary, this invention has the advantages of overcoming impurity enrichment, achieving high recovery quality, and extending the stable operation cycle of the system. Attached Figure Description
[0012] Figure 1 This is a schematic diagram of the overall structure of this utility model; In the diagram: 1-Absorption tower, 2-Exhaust port, 3-Inlet pipe, 4-Drain port, 5-Liquid-liquid precooler, 6-Gas-liquid precooler, 7-Cryogenic cooler, 8-Rough single tower, 9-Spray assembly, 10-Packing layer, 11-Gas-gas mixer, 12-Reflux pipe, 13-Gas-gas precooler, 14-Diverter pipe, 15-Gas-liquid separator, 16-Liquid-liquid mixer. Detailed Implementation
[0013] The present invention will be further described below with reference to the accompanying drawings, but this description is not intended to limit the present invention in any way. Any changes or improvements made based on the present invention shall fall within the protection scope of the present invention.
[0014] like Figure 1 As shown, this utility model includes an absorption tower 1 and a cooler. The top of the absorption tower 1 is provided with an exhaust port 2, the bottom of the absorption tower 1 is provided with an air inlet pipe 3, and the bottom of the absorption tower 1 is provided with a liquid outlet 4. The cooler includes a liquid-liquid precooler 5, a gas-liquid precooler 6, and a cryocooler 7. The liquid outlet 4 is connected to the shell-side inlet of the liquid-liquid precooler 5 through a pipeline. The tube-side outlet of the liquid-liquid precooler 5 is connected to the tube-side inlet of the cryocooler 7 through a pipeline. The tube-side outlet of the cryocooler 7 is connected to the upper part of the absorption tower 1 through a pipeline. The exhaust port 2 is connected to the shell-side inlet of the gas-liquid precooler 6 through a pipeline. The tube-side outlet of the gas-liquid precooler 6 is connected to the tube-side inlet of the cryocooler 7 through a pipeline. The tube-side inlets of both the gas-liquid precooler 6 and the liquid-liquid precooler 5 are connected to the coarse single-unit tower 8. In this invention, the absorption tower 1, liquid-liquid precooler 5, gas-liquid precooler 6, and cryotherm 7 are all existing structures. The absorption tower 1 can be a packed type or a tray type structure, used to absorb chloromethane in noncondensable gas using mixed crude monomers. The liquid-liquid precooler 5 and the gas-liquid precooler 6 can be shell-and-tube heat exchangers, both used to pre-cool the mixed crude monomers and reduce their temperature.
[0015] This invention is used to recover chloromethane from non-condensable gases such as nitrogen and methane. During operation, the mixed crude monomers collected from the crude monomer tower 8 are pressurized by a pump and then sent to the liquid-liquid precooler 5 and the gas-liquid precooler 6 for precooling. Then, they are introduced into the cryogenic cooler 7, where -35℃ Freon R507 is used to further reduce the temperature of the mixed crude monomers to -25℃ to -30℃. The mixed crude monomers are then sent to the upper part of the absorption tower 1. At the same time, non-condensable gas is introduced from the gas inlet pipe 3 at the bottom of the absorption tower 1. The non-condensable gas comes into countercurrent contact with the mixed crude monomers. Taking advantage of the selective absorption characteristics of the mixed crude monomers under low temperature conditions, namely, chloromethane gas has good solubility in the crude monomer liquid, while isobutane, isobutene and other alkanes and alkenes have low solubility in the crude monomer liquid, the chloromethane in the non-condensable gas will be absorbed by the mixed crude monomers, while the remaining non-condensable gas is discharged from the exhaust port at the top of the absorption tower 1. This overcomes the problem of continuous enrichment of impurities such as alkanes and alkenes and achieves the purpose of recovering chloromethane from the non-condensable gas.
[0016] In this invention, compared to traditional methods such as membrane absorption and pressure swing adsorption for recovering chloromethane, the content of harmful impurities such as alkanes and olefins in the washed and recovered chloromethane is significantly reduced by controlling the temperature and pressure during the condensation absorption process. The quality of the recovered chloromethane can be maintained at over 95%, and its return to the fluidized bed reactor effectively improves the normal operating cycle of the fluidized bed reactor and increases the yield and quality of the system products. Secondly, in this invention, the cooling medium in the liquid-liquid precooler 5 is the mixed crude monomer rich in chloromethane discharged from the absorption tower 1. The temperature of the mixed crude monomers is relatively low, which can absorb the heat from the mixed crude monomers discharged from the crude monomer tower 8, thus avoiding the waste of cooling capacity and achieving the purpose of precooling the mixed crude monomers. At the same time, the cooling medium in the gas-liquid precooler 6 is the non-condensable gas discharged from the absorption tower 1 after the separation of chloromethane. The temperature of this non-condensable gas is also relatively low, which can absorb the heat from the mixed crude monomers discharged from the crude monomer tower 8, thus avoiding the waste of cooling capacity and achieving the purpose of precooling the mixed crude monomers. This reduces the operating load of the subsequent cryogenic unit 7 and reduces the amount of Freon used, thus achieving the effect of energy saving and consumption reduction.
[0017] The absorption tower 1 is equipped with a spray assembly 9 and multiple packing layers 10 arranged sequentially from top to bottom. The structures of the spray assembly 9 and multiple packing layers 10 are the internal component structures of the existing chloromethane absorption tower 1. During operation, the mixed crude monomers after condensation are sprayed out from the spray assembly 9 to form a spray falling down, while the non-condensable gas flows upward from the bottom of the absorption tower 1. The two come into contact in opposite directions, and the mixed crude monomers absorb the chloromethane in the non-condensable gas, thereby achieving the recovery of chloromethane. In actual use, a tray structure can also be used, as long as it can effectively absorb the chloromethane in the non-condensable gas.
[0018] A gas-gas mixer 11 is installed on the inlet pipe 3, and the exhaust port 2 is connected to the gas-gas mixer 11 through the return pipe 12. The gas-gas mixer 11 is an existing device used for mixing two or more gases. During the operation of this system, if the absorption tower 1 does not achieve the expected absorption effect of chloromethane in the non-condensable gas due to improper operation or unexpected situations, the discharged non-condensable gas still contains a large amount of chloromethane. At this time, the discharged non-condensable gas can be returned to the gas-gas mixer 11 through the return pipe 12, and the two streams of non-condensable gas are mixed evenly. On the one hand, this can reduce the temperature of the non-condensable gas to be treated and improve the subsequent chloromethane absorption efficiency. On the other hand, it can also perform secondary treatment on the discharged non-condensable gas to further absorb the chloromethane in it.
[0019] A gas-to-gas precooler 13 is installed on the outside of the absorption tower 1. The inlet pipe 3 is connected to the tube side inlet of the gas-to-gas precooler 13, and the tube side outlet of the gas-to-gas precooler 13 is connected to the non-condensable gas inlet on the absorption tower 1. The exhaust port 2 is connected to the shell side inlet of the gas-to-gas precooler 13 through the diverter pipe 14. The gas-to-gas precooler 13 is an existing heat exchange device. In this utility model, the low-temperature non-condensable gas discharged from the absorption tower 1 is used to condense the non-condensable gas to be treated. Through pre-cooling, most of the chloromethane in the non-condensable gas can be condensed into liquid, thereby maximizing the recovery rate of chloromethane, reducing the load on the absorption tower 1, and reducing the waste of cooling capacity in the non-condensable gas discharged from the absorption tower 1.
[0020] The shell-side outlet of the cryogenic cooler 7 is connected to a gas-liquid separator 15 via a pipeline. The drain port of the gas-liquid separator 15 is connected to the top of the shell-side of the cryogenic cooler 7. During system operation, liquid Freon absorbs heat from the mixed crude monomers in the cryogenic cooler 7 and vaporizes to form gaseous Freon. However, in actual use, it was found that some liquid droplets are always entrained in the gaseous Freon. The Freon gas with entrained droplets will enter the subsequent compressor. Since liquids are incompressible, when liquid Freon enters the compressor cylinder, it will generate a huge impact force at the moment of piston compression, which may cause valve plate rupture, connecting rod bending, piston damage, or even directly penetrate the compressor housing, causing catastrophic failure. To avoid this problem, the gas-liquid separator 15 is set up. The gas-liquid separator 15 is an existing device used to separate liquids from the gas, such as a cyclone separator, and returns the separated liquid to the cryogenic cooler 7 to prevent Freon waste and solve the problem of liquid droplets entrained in the Freon gas.
[0021] A liquid-liquid mixer 16 is installed on the inlet pipe of the cryogenic cooler 7. The outlet pipes of the liquid-liquid precooler 5 and the outlet pipes of the gas-liquid precooler 6 are both connected to the liquid-liquid mixer 16. When this invention is in operation, a portion of the mixed coarse monomers are cooled by the low-temperature coarse monomers discharged from the absorption tower 1 in the liquid-liquid precooler 5, and a portion of the mixed coarse monomers are cooled by the low-temperature non-condensable gas discharged from the absorption tower 1 in the gas-liquid precooler 6. The operating conditions, thermal efficiency, and other operating parameters of the liquid-liquid precooler 5 and the gas-liquid precooler 6 are different, resulting in different temperatures of the mixed coarse monomers after precooling. If the mixture is directly introduced into the cryogenic cooler 7 for deep condensation, the unstable temperature of the mixed coarse monomers will affect the heat exchange efficiency of the cryogenic cooler 7. To solve this problem, the liquid-liquid mixer 16 is installed. The liquid-liquid mixer 16 is an existing device used to fully mix two or more liquids, thereby stabilizing the temperature of the mixed coarse monomers entering the cryogenic cooler 7 and ensuring the condensation effect of the mixed coarse monomers in the cryogenic cooler 7.
[0022] This invention utilizes a -35℃ Freon refrigerant to condense and mix crude monomers, followed by low-temperature washing and absorption of chloromethane from the non-condensable gases. This technology prevents an increase in harmful impurities such as isobutane and isobutylene in the absorbed chloromethane by controlling the temperature of the absorbent-mixed crude monomer mixture and the operating pressure of absorption tower 1, thereby improving the quality of recovered chloromethane and facilitating the long-term stable operation of the monomer synthesis fluidized bed reactor. By controlling the condensation and absorption temperature and pressure, harmful impurities such as alkanes and olefins in the washed and recovered chloromethane are reduced, maintaining the quality of recovered chloromethane above 95%, effectively increasing the fluidized bed operating time, and significantly improving both yield and quality.
[0023] This invention uses a mixed crude monomer as the solvent in the chloromethane absorption tower 1. The crude monomer, initially at 45°C, is pressurized to 1.00 MPa (G) by an absorbent delivery pump. It is then pre-cooled by the absorbent liquid and non-condensable gas in a precooler, reducing the absorbent temperature from 45°C to 3°C–5°C. The absorbent then passes through a chloromethane cryocooler 7, where -35°C Freon R507 is used to further cool it from 3°C–5°C to -25°C–-30°C. This cooled absorbent is then used as the reflux liquid in absorption tower 1 to condense and absorb the chloromethane in the non-condensable gas. Synthetic non-condensable gas from the stripping tower is fed into the absorption tower and condensed and absorbed under operating conditions of -25°C–-30°C and 0.5 MPa–0.73 MPa. The mixed crude monomer absorbent is continuously fed and discharged at a rate of 2000 kg / h–3000 kg / h. After condensation and washing in the absorption tower, the chloromethane-containing absorbent liquid is sent to the washing tower reflux tank. The un-condensed non-condensable gas is discharged to the incineration unit for combustion.
Claims
1. A high-efficiency recovery system for chloromethane in non-condensable gases used in organosilicon production, comprising an absorption tower (1) and a cooler, characterized in that: The top of the absorption tower (1) is provided with an exhaust port (2), the bottom of the absorption tower (1) is provided with an air inlet pipe (3), and the bottom of the absorption tower (1) is provided with a liquid outlet (4). The cooler includes a liquid-liquid precooler (5), a gas-liquid precooler (6), and a cryocooler (7). The liquid outlet (4) is connected to the shell-side inlet of the liquid-liquid precooler (5) through a pipeline. The tube-side outlet of the liquid-liquid precooler (5) is connected to the tube-side inlet of the cryocooler (7) through a pipeline. The tube-side outlet of the cryocooler (7) is connected to the upper part of the absorption tower (1) through a pipeline. The exhaust port (2) is connected to the shell-side inlet of the gas-liquid precooler (6) through a pipeline. The tube-side outlet of the gas-liquid precooler (6) is connected to the tube-side inlet of the cryocooler (7) through a pipeline. The tube-side inlets of the gas-liquid precooler (6) and the liquid-liquid precooler (5) are both connected to the coarse single tower (8).
2. The high-efficiency recovery system for chloromethane in non-condensable gases used in organosilicon production according to claim 1, characterized in that: The absorption tower (1) is provided with a spray assembly (9) and multiple packing layers (10) arranged from top to bottom.
3. The high-efficiency recovery system for chloromethane in non-condensable gases used in organosilicon production according to claim 1, characterized in that: An air-to-air mixer (11) is provided on the air intake pipe (3), and the exhaust port (2) is connected to the air-to-air mixer (11) through the return pipe (12).
4. The high-efficiency recovery system for chloromethane in non-condensable gases used in organosilicon production according to claim 1, characterized in that: A gas-to-gas precooler (13) is provided on the outside of the absorption tower (1). The inlet pipe (3) is connected to the tube side inlet of the gas-to-gas precooler (13). The tube side outlet of the gas-to-gas precooler (13) is connected to the non-condensable gas inlet on the absorption tower (1). The exhaust port (2) is connected to the shell side inlet of the gas-to-gas precooler (13) through the diversion pipe (14).
5. The high-efficiency recovery system for chloromethane in non-condensable gases used in organosilicon production according to claim 1, characterized in that: The shell-side outlet of the cryogenic unit (7) is connected to a gas-liquid separator (15) via a pipeline, and the drain port of the gas-liquid separator (15) is connected to the top of the shell-side of the cryogenic unit (7).
6. The high-efficiency recovery system for chloromethane in non-condensable gases used in organosilicon production according to claim 1, characterized in that: A liquid-liquid mixer (16) is installed on the inlet pipe of the cryogenic cooler (7), and the outlet pipe of the liquid-liquid precooler (5) and the outlet pipe of the gas-liquid precooler (6) are both connected to the liquid-liquid mixer (16).