A thionyl chloride production system

Abstract

This invention belongs to the field of thionyl chloride technology and discloses a thionyl chloride production system, including a synthesis system and a refining system. The synthesis system includes a synthesis kettle, a mixing preheater, and a reactor. The refining system includes a degassing tower, a degassing tower top condenser, a circulating gas condenser, a distillation tower, a distillation tower reboiler, a distillation tower top condenser, a de-heavyness tower, and a de-heavyness tower top condenser. This invention uses heat exchange between the high-temperature crude thionyl chloride and the cold material at the bottom of the distillation tower, saving energy. Preheating the feed gas in the mixing preheater with heat transfer oil not only utilizes the heat transferred to the heat transfer oil from the synthesis reaction but also prevents temperature imbalances in the reactor before the heated feed gas enters, thereby improving the reaction conversion rate.

Description

Technical Field

[0001] This utility model belongs to the field of thionyl chloride technology, and specifically relates to a thionyl chloride production system. Background Technology

[0002] Thionyl chloride, chemical formula SOCl2, also known as thionyl chloride or thionyl chloride, is a highly potent chlorinating, acyl-chlorinating, and dehydrating agent. It is an important raw material for fine chemicals and a synthetic intermediate for chemical products. The sulfur dioxide gas-phase process is the mainstream technology for producing thionyl chloride. Generally, sulfur and liquid chlorine react in a synthesis reactor to produce synthesis gas (2S + Cl2 → S2Cl2; S2Cl2 + Cl2 → 2SCl2). This synthesis gas, along with sulfur dioxide and chlorine, enters a reactor (SCl2 + SO2 + Cl2 → 2SOCl2) to generate high-temperature crude thionyl chloride gas. After condensation and distillation, the final product, thionyl chloride, is obtained. The temperature of the crude thionyl chloride gas is between 250 and 300°C. Typical refining systems do not consider utilizing this preheating, leading to increased energy consumption in the refining system. In addition, in existing processes, synthesis gas is generally introduced directly into the reactor along with sulfur dioxide and chlorine. The reactor is a tubular fixed-bed reactor. Since the synthesis reaction of thionyl chloride in the reactor (an exothermic reaction) takes place at 180~300℃, heat transfer oil is needed to heat the feed gas to reach the reaction temperature during start-up. As the reaction proceeds, the heating of the feed gas by heat transfer oil can be stopped, and the natural circulation of the heat transfer oil can be used to ensure uniform temperature inside the reactor. However, the heat of the heat transfer oil is not utilized, resulting in energy waste. Summary of the Invention

[0003] This invention addresses the technical problem of insufficient energy utilization in traditional thionyl chloride production by providing a thionyl chloride production system. The system exchanges heat between the high-temperature crude thionyl chloride and the cold material in the bottom of the distillation column, saving energy. Furthermore, by preheating the feed gas in the mixing preheater with heat transfer oil, not only can the heat transferred to the heat transfer oil from the synthesis reaction be utilized, but the preheated feed gas entering the reactor also avoids temperature imbalances within the reactor, thereby improving the reaction conversion rate.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: A thionyl chloride production system includes a synthesis system and a purification system. The synthesis system includes a synthesis kettle, a mixing preheater, and a reactor. The purification system includes a degassing tower, a degassing tower top condenser, a circulating gas condenser, a distillation tower, a distillation tower reboiler, a distillation tower top condenser, a de-heavy gas removal tower, and a de-heavy gas removal tower top condenser. The synthesis gas outlet of the synthesis kettle is connected to the reactor via the mixing preheater. The crude thionyl chloride outlet of the reactor is connected to the feed inlet of the degassing tower via the distillation tower reboiler. The top gas outlet of the degassing tower is connected to the feed inlet of the degassing tower via the degassing tower top condenser and the circulating gas condenser. The top reflux port of the degassing tower is connected to the feed inlet of the mixing preheater. The bottom liquid outlet of the degassing tower is connected to the feed inlet of the distillation tower. The bottom liquid outlet of the distillation tower is connected to the bottom liquid inlet of the distillation tower and the feed inlet of the heavy removal tower via the distillation tower reboiler. The top gas outlet of the distillation tower is connected to the top reflux port of the distillation tower via the distillation tower top condenser. The bottom sulfur monochloride outlet of the heavy removal tower is connected to the sulfur monochloride inlet of the synthesis reactor. The top gas outlet of the heavy removal tower is connected to the top reflux port of the heavy removal tower and the thionyl chloride product tank via the heavy removal tower top condenser.

[0005] In one technical solution, the reactor is a tubular fixed-bed reactor, wherein the tube side of the tubular fixed-bed reactor is filled with activated carbon catalyst and the shell is filled with heat transfer oil.

[0006] In one technical solution, the shell heat transfer oil outlet of the tubular fixed bed reactor is connected to the shell heat transfer oil inlet of the tubular fixed bed reactor via a heat transfer oil heater and a mixing preheater.

[0007] In one technical solution, the synthesis system further includes a heat transfer oil circulation pump, which is installed on the connecting pipeline between the outlet of the heat transfer oil heater and the heat transfer oil inlet of the mixing preheater.

[0008] In one technical solution, the degassing tower top condenser is located at the top of the degassing tower.

[0009] In one technical solution, the refining system further includes an ejector, which is disposed on the connecting pipeline between the circulating liquid outlet of the circulating gas condenser and the raw material inlet of the mixing preheater.

[0010] In one technical solution, the refining system further includes a degassing tower top circulation pump, which is installed on the connecting pipeline between the circulating liquid outlet of the circulating gas condenser and the top reflux port of the degassing tower.

[0011] In one technical solution, the refining system further includes a first sulfur tank, which is located at the top of the distillation column, and the top gas outlet of the distillation column is connected to the gas inlet of the top condenser of the distillation column via the first sulfur tank.

[0012] In one technical solution, the refining system further includes a second sulfur tank, which is located at the top of the deweighting tower. The gas outlet at the top of the deweighting tower is connected to the gas inlet of the condenser at the top of the deweighting tower via the second sulfur tank.

[0013] Compared with the prior art, the beneficial effects of this utility model are as follows: This invention utilizes the heat from the high-temperature crude thionyl chloride to heat the cold material in the bottom of the distillation column. After the crude thionyl chloride is cooled, it enters the degassing column, making full use of the waste heat in the thionyl chloride production system. On the one hand, it eliminates the need for a condenser to cool the crude thionyl chloride and the heating steam for the reboiler of the distillation column in the traditional process, saving energy consumption and circulating water usage.

[0014] This invention adds a mixing preheater between the synthesis kettle and the reactor. After the reaction in the reactor stabilizes, the heat transfer oil in the reactor is drawn out and used to preheat the raw material gas in the mixing preheater. This not only utilizes the heat transferred to the heat transfer oil by the synthesis reaction, but also prevents temperature imbalance in the reactor when the heated raw material gas re-enters the reactor, thereby improving the reaction conversion rate. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of a thionyl chloride production system according to the present invention.

[0016] The following labels are used in the attached diagram: 1 is the synthesis vessel, 2 is the mixing preheater, 3 is the reactor, 4 is the thermal oil heater, 5 is the thermal oil circulation pump, 6 is the auxiliary heat exchanger, 7 is the degassing tower, 8 is the degassing tower top condenser, 9 is the circulating gas condenser, 10 is the degassing tower top circulation pump, 11 is the ejector, 12 is the distillation tower, 13 is the distillation tower reboiler, 14 is the distillation tower top condenser, 15 is the first sulfur tank, 16 is the de-heavy gas tower, 17 is the second sulfur tank, and 18 is the de-heavy gas tower top condenser. Detailed Implementation

[0017] The following embodiments are used to illustrate the present invention, but are not intended to limit the scope of protection of the present invention.

[0018] like Figure 1 As shown, this utility model discloses a thionyl chloride production system, comprising a synthesis system and a purification system. The synthesis system includes a synthesis vessel 1, a mixing preheater 2, and a reactor 3. The purification system includes a degassing tower 7, a degassing tower top condenser 8, a circulating gas condenser 9, a distillation tower 12, a distillation tower reboiler 13, a distillation tower top condenser 14, a de-heavyness tower 16, and a de-heavyness tower top condenser 18.

[0019] like Figure 1As shown, the syngas outlet of synthesis reactor 1 is connected to reactor 3 via mixing preheater 2. Specifically, the syngas outlet of synthesis reactor 1 is connected to the raw material inlet of mixing preheater 2, and the raw material outlet of mixing preheater 2 is connected to the raw material inlet of reactor 3. Liquid sulfur and chlorine enter synthesis reactor 1. Syngas containing a large amount of sulfur dichloride and a small amount of sulfur monochloride enters mixing preheater 2, while sulfur dioxide gas-liquid enters mixing preheater 2. Mixing preheater 2 preheats and mixes the syngas, sulfur dioxide gas, and circulating gas before entering reactor 3 for thionyl chloride synthesis to obtain crude thionyl chloride. The crude thionyl chloride mainly consists of sulfur dichloride (boiling point 59℃), sulfone chloride (boiling point 69℃), thionyl chloride (boiling point 78.8℃), sulfur monochloride (heavy component, boiling point 138℃), Cl2, and SO2. After being processed by degassing tower 7, distillation tower 12, and heavy component removal tower 15, qualified thionyl chloride is obtained.

[0020] like Figure 1 As shown, the crude thionyl chloride outlet of reactor 3 is connected to the feed inlet of degassing tower 7 via the reboiler 13 of the distillation column. Specifically, the crude thionyl chloride outlet of reactor 3 is connected to the hot material inlet of the reboiler 13, and the hot material outlet of the reboiler 13 is connected to the feed inlet of degassing tower 7. The heat from the high-temperature crude thionyl chloride heats the cold material in the bottom of distillation column 12, and the crude thionyl chloride is cooled before entering degassing tower 7. This fully utilizes the waste heat within the thionyl chloride production system, eliminating the need for a condenser to cool the crude thionyl chloride and the heating steam for the reboiler 13 in traditional processes, thus saving energy and circulating water consumption.

[0021] like Figure 1 As shown, the gas outlet at the top of the degassing tower 7 is connected to the reflux port at the top of the degassing tower 7 and the raw material inlet of the mixing preheater 2 via the top condenser 8 and the circulating gas condenser 9, respectively. Specifically, the gas outlet at the top of the degassing tower 7 is connected to the gas inlet of the top condenser 8, the gas outlet of the top condenser 8 is connected to the circulating gas inlet of the circulating gas condenser 9, and the circulating liquid outlet of the circulating gas condenser 9 is connected to the reflux port at the top of the degassing tower 7. In other words, the circulating liquid in the circulating gas condenser 9 is divided into two streams: one stream serves as the reflux liquid for the degassing tower 7, and the other stream returns the condensed chlorine and sulfur dioxide as circulating gas to the raw material inlet of the mixing preheater 2 for reuse in the synthesis of thionyl chloride.

[0022] like Figure 1As shown, the bottom liquid outlet of the degassing column 7 is connected to the feed inlet of the distillation column 12. The bottom liquid outlet of the distillation column 12 is connected to the bottom liquid inlet of the distillation column 12 and the feed inlet of the heavy removal column 16 via the reboiler 13. That is, the bottom liquid outlet of the distillation column 12 is connected to the cold material inlet of the reboiler 13 and the feed inlet of the heavy removal column 16, and the cold material outlet of the reboiler 13 is connected to the bottom liquid inlet of the distillation column 12. The top gas outlet of the distillation column 12 is connected to the top reflux inlet of the distillation column 12 via the top condenser 14. That is, the top gas outlet of the distillation column 12 is connected to the gas inlet of the top condenser 14, and the condensate outlet of the top condenser 14 is connected to the top reflux inlet of the distillation column 12.

[0023] like Figure 1 As shown, the sulfur chloride outlet at the bottom of the de-heavy column 16 is connected to the sulfur chloride inlet of the synthesis reactor 1. The gas outlet at the top of the de-heavy column 16 is connected to the reflux inlet at the top of the de-heavy column 16 and the thionyl chloride product tank via the top condenser 18. That is, the gas outlet at the top of the de-heavy column 16 is connected to the gas inlet of the top condenser 18, and the condensate outlet of the top condenser 18 is connected to the reflux inlet at the top of the de-heavy column 16 and the thionyl chloride product tank.

[0024] In one embodiment, the reactor 3 of this invention is a tubular fixed-bed reactor, with activated carbon catalyst in the tubes and heat transfer oil in the shell. The heat transfer oil outlet of the shell of the tubular fixed-bed reactor is connected to the heat transfer oil inlet of the shell of the tubular fixed-bed reactor after passing through a heat transfer oil heater 4 and a mixing preheater 2. It should be noted that during start-up, the heat transfer oil heater 4 is turned on to heat the heat transfer oil. After the reaction temperature in the reactor 3 reaches the required temperature, the heat transfer oil heater 4 is turned off. After the reaction in the reactor 3 stabilizes, by adding a mixing preheater 2 between the synthesis vessel 1 and the reactor 2, the heat transfer oil in the reactor 3 can be drawn out. The heat transfer oil is used to preheat the feed gas in the mixing preheater 2. This not only utilizes the heat transferred to the heat transfer oil by the synthesis reaction, but also prevents temperature imbalance in the reactor 3 when the heated feed gas re-enters the reactor 3, thereby improving the reaction conversion rate. If the temperature of the heat transfer oil exiting the mixing preheater 2 is still too high, it can be cooled again by an auxiliary heat exchanger 6 before entering the reactor 2.

[0025] In order to ensure stable circulation of the heat transfer oil, the synthesis system of this utility model also includes a heat transfer oil circulation pump 5, which is installed on the connecting pipeline between the outlet of the heat transfer oil heater 4 and the heat transfer oil inlet of the mixing preheater 2.

[0026] To reduce the floor space required, the top condenser 8 of the degassing tower can be installed at the top of the degassing tower 7.

[0027] In order to maintain stable system pressure, the condensed chlorine and sulfur dioxide need to be re-vaporized. The refining system of this utility model also includes an ejector 11, which is installed on the connecting pipeline between the circulating liquid outlet of the circulating gas condenser 9 and the raw material inlet of the mixing preheater 2. After being expanded and pressurized by the ejector 11, the chlorine and sulfur dioxide are re-vaporized and enter the mixing preheater 2.

[0028] The refining system of this utility model also includes a degassing tower top circulation pump 10, which is installed on the connecting pipeline between the circulating liquid outlet of the circulating gas condenser 9 and the top reflux port of the degassing tower 7.

[0029] In order to remove sulfur dichloride and sulfone chloride from the top of the distillation column 12 and reduce the entry of low-valent sulfur chlorides into the tail gas absorption system, the purification system of this utility model also includes a first sulfur tank 15. The first sulfur tank 15 is located at the top of the distillation column 12, and the gas outlet at the top of the distillation column 12 is connected to the gas inlet of the top condenser 14 of the distillation column via the first sulfur tank 15.

[0030] In order to further remove sulfur dichloride entrained in the product gas and improve the purity of the product, the purification system of this utility model also includes a second sulfur tank 17. The second sulfur tank 17 is located at the top of the deweight removal tower 16, and the gas outlet at the top of the deweight removal tower 16 is connected to the gas inlet of the top condenser 18 of the deweight removal tower via the second sulfur tank 17.

[0031] In one embodiment, the light component removal tower 7 operates under pressure, with a pressure range of 0.2~0.3 MPa, a top temperature of 70~80°C, and a bottom temperature of 110~150°C. Light components chlorine and sulfur dioxide enter the top of the light component removal tower 7. Unvaporized sulfur dichloride, sulfone chloride, and thionyl chloride remain in the bottom of the light component removal tower 7 and are used as feed to the distillation tower 12. The distillation tower 12 operates under pressure, with a pressure range of 0.2~0.3 MPa, a top temperature of 70~80°C, and a bottom temperature of 90~100°C. Sulfur dichloride and sulfone chloride are vaporized and enter the top of the distillation tower 12. After being treated with sulfur, the sulfur dichloride and sulfone chloride are reduced to sulfur monochloride and refluxed back to the distillation tower 12. Unvaporized thionyl chloride and sulfur monochloride remain in the bottom of the distillation tower 12 and are used as feed to the heavy component removal tower 15. The heavy component removal tower 15 operates under pressure, with a pressure range of 0.1~0.2 MPa. MPa, top temperature 70~85℃, bottom temperature 130~145℃, a small amount of sulfur dichloride entrained in the product gas is further removed by sulfur treatment to improve the purity of the product thionyl chloride. The thionyl chloride is partially refluxed and partially collected after being condensed by the top condenser 18 of the deweighting tower. The heavy component monochloride at the bottom of the tower is returned to the synthesis reactor 1 for recycling.

[0032] The embodiments described above are merely preferred embodiments of this utility model and are only used to explain this utility model. They are not intended to limit the scope of implementation of this utility model. For those skilled in the art, other implementation methods can be easily made by substitution or modification based on the technical content disclosed in this specification. Therefore, all changes and improvements made on the principle of this utility model should be included within the scope of the patent application of this utility model.

Claims

1. A thionyl chloride production system, comprising a synthesis system and a purification system, characterized in that, The synthesis system includes a synthesis vessel (1), a mixing preheater (2), and a reactor (3). The refining system includes a degassing tower (7), a degassing tower top condenser (8), a circulating gas condenser (9), a distillation tower (12), a distillation tower reboiler (13), a distillation tower top condenser (14), a de-heavy tower (16), and a de-heavy tower top condenser (18). The synthesis gas outlet of the synthesis vessel (1) is connected to the reactor (3) via the mixing preheater (2). The crude thionyl chloride outlet of the reactor (3) is connected to the feed inlet of the degassing tower (7) via the distillation tower reboiler (13). The top gas outlet of the degassing tower (7) is connected to the top gas outlet of the degassing tower (7) via the degassing tower top condenser (8) and the circulating gas condenser (9), respectively. The top reflux port and the raw material inlet of the mixing preheater (2) are connected. The bottom liquid outlet of the degassing tower (7) is connected to the feed inlet of the distillation tower (12). The bottom liquid outlet of the distillation tower (12) is connected to the bottom liquid inlet of the distillation tower (12) and the feed inlet of the de-heavy tower (16) via the distillation tower reboiler (13). The top gas outlet of the distillation tower (12) is connected to the top reflux inlet of the distillation tower (12) via the distillation tower top condenser (14). The bottom sulfur monochloride outlet of the de-heavy tower (16) is connected to the sulfur monochloride inlet of the synthesis kettle (1). The top gas outlet of the de-heavy tower (16) is connected to the top reflux inlet of the de-heavy tower (16) and the thionyl chloride product tank via the de-heavy tower top condenser (18).

2. The thionyl chloride production system according to claim 1, characterized in that, The reactor (3) is a tubular fixed-bed reactor, with activated carbon catalyst in the tube side and heat transfer oil in the shell.

3. The thionyl chloride production system according to claim 2, characterized in that, The shell heat transfer oil outlet of the tubular fixed bed reactor is connected to the shell heat transfer oil inlet of the tubular fixed bed reactor via a heat transfer oil heater (4) and a mixing preheater (2).

4. A thionyl chloride production system according to claim 3, characterized in that, The synthesis system also includes a heat transfer oil circulation pump (5), which is installed on the connecting pipeline between the outlet of the heat transfer oil heater (4) and the heat transfer oil inlet of the mixing preheater (2).

5. A thionyl chloride production system according to claim 1, characterized in that, The degassing tower top condenser (8) is located at the top of the degassing tower (7).

6. A thionyl chloride production system according to claim 1, characterized in that, The refining system also includes an injector (11), which is located on the connecting pipeline between the circulating liquid outlet of the circulating gas condenser (9) and the raw material inlet of the mixing preheater (2).

7. A thionyl chloride production system according to claim 1, characterized in that, The refining system also includes a degassing tower top circulation pump (10), which is installed on the connecting pipeline between the circulating liquid outlet of the circulating gas condenser (9) and the top reflux port of the degassing tower (7).

8. A thionyl chloride production system according to claim 1, characterized in that, The refining system also includes a first sulfur tank (15), which is located at the top of the distillation column (12). The gas outlet at the top of the distillation column (12) is connected to the gas inlet of the condenser (14) at the top of the distillation column via the first sulfur tank (15).

9. A thionyl chloride production system according to claim 1, characterized in that, The refining system also includes a second sulfur tank (17), which is located at the top of the deweighting tower (16). The gas outlet at the top of the deweighting tower (16) is connected to the gas inlet of the top condenser (18) of the deweighting tower via the second sulfur tank (17).

Images