Waste heat recovery system for anhydrous hydrogen fluoride production

Abstract

This utility model discloses a waste heat recovery system for anhydrous hydrogen fluoride production, including a stripping tower, a buffer tank, and a heat exchanger. The stripping tower has a high-temperature dilute sulfuric acid inlet pipe and a gas phase outlet pipe at the top, and a liquid phase outlet pipe and a steam inlet pipe at the bottom. The liquid phase outlet pipe connects to the buffer tank, and the liquid phase delivery pipe at the bottom of the buffer tank connects to the tube side of the heat exchanger. The shell side of the heat exchanger connects to the inlet and outlet pipes of the raw material fluorosilicic acid, and has a jacket on its outer wall. The gas phase outlet pipe of the stripping tower connects to the jacket, and the jacket has a mixed gas output pipe. The buffer tank has staggered baffles forming an "S"-shaped flow channel. The liquid phase delivery pipe is equipped with a delivery pump. The buffer tank is equipped with a level gauge connected to a control module and also has a pressure safety valve. This utility model recovers the waste heat of high-temperature dilute sulfuric acid and gas phase products through the heat exchanger tube side and jacket respectively, heating the shell side raw material fluorosilicic acid. This solves the problems of incomplete waste heat recovery and high energy consumption for raw material heating in traditional methods, achieving efficient utilization of waste heat, reducing production energy consumption and costs, and ensuring stable and safe system operation.

Description

Technical Field

[0001] This utility model relates to the field of anhydrous hydrogen fluoride production technology, specifically a waste heat recovery system for anhydrous hydrogen fluoride production. Background Technology

[0002] Anhydrous hydrogen fluoride (HF) is a key inorganic chemical raw material in the fields of fluorochemicals and electronic materials. The sulfuric acid process is currently the mainstream method for its industrial production due to the readily available raw materials and mature technology. This process uses fluorite (mainly CaF2) and concentrated sulfuric acid as raw materials, reacting them at high temperatures to produce hydrogen fluoride gas and calcium sulfate. The reaction requires maintaining high temperatures and is accompanied by a large amount of exothermic reaction. After the reaction, high-temperature dilute sulfuric acid with a temperature of 120-180℃ is produced, containing abundant residual heat. Simultaneously, during the subsequent hydrogen fluoride purification process, the gaseous products (containing hydrogen fluoride, water vapor, etc.) discharged from the top of the stripping tower also carry a certain amount of heat.

[0003] In traditional processes, much of this waste heat is not effectively recovered. High-temperature dilute sulfuric acid needs to be cooled by cooling equipment before being sent for further processing, while gaseous products are either directly discharged or discharged after simple treatment. This not only wastes a lot of heat energy and increases the energy consumption and costs of enterprises, but also requires additional cooling water resources and electricity, which violates the development concepts of "energy conservation and emission reduction" and "green chemical industry".

[0004] Some companies have tried to use heat exchangers to recover the waste heat of high-temperature dilute sulfuric acid, but there are obvious shortcomings: First, high-temperature dilute sulfuric acid contains a small amount of hydrogen fluoride and solid impurities, which can easily lead to equipment corrosion and blockage if directly introduced into the heat exchanger, affecting its lifespan and heat exchange efficiency; Second, only the waste heat of dilute sulfuric acid is recovered, ignoring the heat of the gas phase products in the stripping tower, resulting in incomplete recovery and low energy utilization.

[0005] Furthermore, the pretreatment of fluorosilicic acid, the raw material in anhydrous hydrogen fluoride production, requires heating to 60-80°C, which currently relies heavily on steam or electric heating, further increasing energy consumption. Therefore, achieving efficient and comprehensive waste heat recovery and reuse in processes such as raw material pretreatment is a pressing technical challenge for anhydrous hydrogen fluoride production enterprises. Summary of the Invention

[0006] The technical problem to be solved by this utility model is to provide a waste heat recovery system for anhydrous hydrogen fluoride production, which can solve the technical problems of incomplete waste heat recovery from high-temperature dilute sulfuric acid and stripping tower gas phase products in anhydrous hydrogen fluoride production, as well as high energy consumption for heating raw material fluorosilicic acid, thereby achieving efficient and comprehensive waste heat recovery and reducing production energy consumption.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a waste heat recovery system for anhydrous hydrogen fluoride production, including a stripping tower, a buffer tank and a heat exchanger. The upper part of the stripping tower is provided with a high-temperature dilute sulfuric acid inlet pipe and a gas phase outlet pipe, and the lower part of the stripping tower is provided with a liquid phase outlet pipe and a steam inlet pipe. The liquid phase outlet pipe is connected to the buffer tank, and the bottom of the buffer tank is provided with a liquid phase conveying pipe, which is connected to the tube side of the heat exchanger. The heat exchanger is equipped with a raw material fluorosilicic acid inlet pipe and a raw material fluorosilicic acid outlet pipe connected to its shell side. The heat exchanger is provided with a jacket on its outer wall, and the gas phase outlet pipe at the top of the stripping tower is connected to the jacket. The jacket is also provided with a mixed gas outlet pipe.

[0008] In a preferred embodiment, the buffer tank is equipped with baffles, which are staggered within the buffer tank to form an "S"-shaped flow channel.

[0009] In a preferred embodiment, a liquid phase transport pump is provided on the liquid phase transport pipe.

[0010] In a preferred embodiment, the buffer tank is equipped with a level gauge, and both the level gauge and the liquid phase transfer pump are connected to the control module.

[0011] In a preferred embodiment, the buffer tank is equipped with a pressure safety valve at the top.

[0012] In a preferred embodiment, the raw material fluorosilicic acid inlet pipe is equipped with a raw material fluorosilicic acid transfer pump.

[0013] In a preferred embodiment, the mixed gas output pipe is equipped with a condenser recovery unit, and the bottom of the condenser recovery unit is equipped with a condensate discharge pipe.

[0014] The waste heat recovery system for anhydrous hydrogen fluoride production provided by this utility model, by adopting the above-described structure, has the following beneficial effects: (1) The system is connected to the liquid phase outlet pipe at the bottom of the stripping tower through the heat exchanger tube side to recover the waste heat of high-temperature dilute sulfuric acid; at the same time, the heat exchanger outer wall jacket is connected to the gas phase outlet pipe at the top of the stripping tower to recover the waste heat of the gas phase products, forming a dual recovery of the waste heat of the two high-temperature media. Compared with the traditional method of only recovering the waste heat of dilute sulfuric acid, the waste heat recovery scope of this application is more comprehensive, which can make full use of the originally wasted heat energy, greatly improve the energy utilization rate, and reduce the energy consumption of enterprises. (2) High-temperature dilute sulfuric acid first passes through a buffer tank and then enters the tube side of the heat exchanger. The baffles arranged in the buffer tank form an “S” shaped flow channel, which can slow down the flow rate of the medium and reduce the impact and wear on the subsequent heat exchanger. In addition, the buffer tank can also play a role in stabilizing the pressure, avoiding the instability of the heat exchanger operating conditions caused by the fluctuation of the medium flow rate, effectively extending the service life of the equipment and reducing maintenance costs. (3) Fluorosilicic acid, the raw material to be heated, is introduced into the shell side of the heat exchanger. The recovered waste heat is used to heat it to 60-80°C, which is required for pretreatment. This replaces the traditional steam or electric heating method and directly reduces the energy consumption of the heating process. At the same time, the temperature of high-temperature dilute sulfuric acid and gaseous products is reduced after the waste heat is recovered, which reduces the load on the subsequent cooling equipment and the consumption of cooling water and electricity, thereby reducing the overall production cost of the enterprise from multiple aspects. Attached Figure Description

[0015] The present invention will be further described below with reference to the accompanying drawings and embodiments: Figure 1 This is a schematic diagram of the overall structure of this utility model.

[0016] In the diagram: 1. Stripping tower; 2. Buffer tank; 3. Heat exchanger; 4. High-temperature dilute sulfuric acid inlet pipe; 5. Gas phase outlet pipe; 6. Liquid phase outlet pipe; 7. Baffle plate; 8. Liquid phase conveying pipe; 9. Liquid phase conveying pump; 10. Jacket; 11. Raw material fluorosilicic acid inlet pipe; 12. Raw material fluorosilicic acid conveying pump; 13. Raw material fluorosilicic acid outlet pipe; 14. Mixed gas output pipe; 15. Pressure safety valve; 16. Liquid level gauge; 17. Control module; 18. Condensate recovery unit; 19. Condensate discharge pipe. Detailed Implementation

[0017] like Figure 1 In the present invention, a waste heat recovery system for anhydrous hydrogen fluoride production includes a stripping tower 1, a buffer tank 2, and a heat exchanger 3. The upper part of the stripping tower 1 is provided with a high-temperature dilute sulfuric acid inlet pipe 4 and a gas phase outlet pipe 5, and the lower part of the stripping tower 1 is provided with a liquid phase outlet pipe 6 and a steam inlet pipe. The liquid phase outlet pipe 6 is connected to the buffer tank 2, and the bottom of the buffer tank 2 is provided with a liquid phase conveying pipe 8, which is connected to the tube side of the heat exchanger 3. The heat exchanger 3 is provided with a raw material fluorosilicic acid inlet pipe 11 and a raw material fluorosilicic acid outlet pipe 13 connected to its shell side. The heat exchanger 3 is provided with a jacket 10 on its outer wall. The gas phase outlet pipe 5 at the top of the stripping tower 1 is connected to the jacket 10. The jacket 10 is also provided with a mixed gas outlet pipe 14.

[0018] In a preferred embodiment, the buffer tank 2 is provided with baffles 7, which are staggered in the buffer tank 2 to form an "S" shaped flow channel.

[0019] In a preferred embodiment, a liquid phase transport pump 9 is provided on the liquid phase transport pipe 8.

[0020] In a preferred embodiment, the buffer tank 2 is equipped with a level gauge 16, and both the level gauge 16 and the liquid phase transfer pump 9 are connected to the control module 17.

[0021] In a preferred embodiment, the top of the buffer tank 2 is provided with a pressure safety valve 15.

[0022] In a preferred embodiment, the raw material fluorosilicic acid inlet pipe 11 is equipped with a raw material fluorosilicic acid transfer pump 12.

[0023] In a preferred embodiment, the mixed gas output pipe 14 is provided with a condenser 18, and the bottom of the condenser 18 is provided with a condensate discharge pipe 19.

[0024] The working principle of the waste heat recovery system for anhydrous hydrogen fluoride production disclosed in this utility model is as follows: High-temperature dilute sulfuric acid (120-180℃) generated during the anhydrous hydrogen fluoride production process enters the stripping tower 1 through the high-temperature dilute sulfuric acid inlet pipe 4 at the top. After gas-liquid separation in the stripping tower, the liquid phase dilute sulfuric acid containing residual heat is discharged from the liquid phase outlet pipe 6 at the bottom of the stripping tower and enters the buffer tank 2. The baffles 7 arranged in a staggered manner in the buffer tank 2 form an "S"-shaped flow channel, which slows down the medium flow rate, stabilizes the pressure, and avoids the impact or flow fluctuation on subsequent equipment. The buffered dilute sulfuric acid enters the tube side of the heat exchanger 3 through the bottom liquid phase conveying pipe 8, driven by the liquid phase conveying pump 9. It exchanges heat with the low-temperature raw material fluorosilicic acid in the shell side of the heat exchanger 3. After the dilute sulfuric acid temperature drops, it is sent to the downstream processing process, and the residual heat it carries is transferred to the fluorosilicic acid in the shell side.

[0025] Meanwhile, the gaseous products (containing hydrogen fluoride, water vapor, etc., carrying residual heat) generated by gas-liquid separation in the stripping tower 1 are transported to the jacket 10 on the outer wall of the heat exchanger 3 through the upper gas phase outlet pipe 5. The jacket 10 encloses the main body of the heat exchanger 3. When the gaseous products flow in the jacket 10, the residual heat they carry is transferred to the dilute sulfuric acid in the tube side through the shell of the heat exchanger 3, thereby indirectly heating the fluorosilicic acid in the shell side, realizing the secondary utilization of the gaseous waste heat. After the heat exchange is completed, the gaseous products form a mixed gas, which is discharged through the mixed gas outlet pipe 14 on the jacket. If further processing is required, it can enter the condenser recovery unit 18 for condensation, and the condensate is collected from the bottom condensate outlet pipe 19.

[0026] In addition, the low-temperature raw material fluorosilicic acid, which requires pretreatment, enters the shell side of the heat exchanger 3 through the raw material fluorosilicic acid inlet pipe 11 under the action of the raw material fluorosilicic acid transfer pump 12. The fluorosilicic acid in the shell side undergoes efficient heat exchange with the composite heat source formed by the high-temperature dilute sulfuric acid in the tube side and the hot gas phase products in the jacket, and the temperature gradually rises to the 60-80℃ required for pretreatment. Finally, it is transported to the subsequent production process through the raw material fluorosilicic acid outlet pipe 13 to realize the resource utilization of waste heat.

[0027] This application also includes an automatic safety control system. The level gauge 16 on the buffer tank 2 monitors the liquid level in the tank in real time and transmits the data to the control module 17. The control module 17 adjusts the operating frequency of the liquid phase transfer pump 9 according to the liquid level signal to ensure the stability of the liquid level in the buffer tank 2 (for example, when the liquid level is lower than the lower limit, the transfer pump automatically reduces the frequency and when the liquid level is higher than the upper limit, the transfer pump automatically increases the frequency to maintain the liquid level in the tank within a reasonable range). The pressure safety valve 15 on the top of the buffer tank 2 automatically opens to release pressure when the pressure in the tank exceeds the set value, preventing overpressure damage to the equipment and ensuring the safety and stability of the entire system operation.

Claims

1. A waste heat recovery system for anhydrous hydrogen fluoride production, characterized in that: It includes a stripping tower (1), a buffer tank (2) and a heat exchanger (3). The upper part of the stripping tower (1) is provided with a high-temperature dilute sulfuric acid inlet pipe (4) and a gas phase outlet pipe (5). The lower part of the stripping tower (1) is provided with a liquid phase outlet pipe (6) and a steam inlet pipe. The liquid phase outlet pipe (6) is connected to the buffer tank (2). The bottom of the buffer tank (2) is provided with a liquid phase conveying pipe (8). The liquid phase conveying pipe (8) is connected to the tube side of the heat exchanger (3). The heat exchanger (3) is provided with a raw material fluorosilicic acid inlet pipe (11) and a raw material fluorosilicic acid outlet pipe (13) connected to its shell side. The heat exchanger (3) is provided with a jacket (10) on its outer wall. The gas phase outlet pipe (5) at the top of the stripping tower (1) is connected to the jacket (10). The jacket (10) is also provided with a mixed gas outlet pipe (14).

2. The waste heat recovery system for anhydrous hydrogen fluoride production according to claim 1, characterized in that: The buffer tank (2) is equipped with baffles (7), which are staggered in the buffer tank (2) to form an "S" shaped flow channel.

3. The waste heat recovery system for anhydrous hydrogen fluoride production according to claim 1, characterized in that: A liquid phase transport pump (9) is provided on the liquid phase transport pipe (8).

4. The waste heat recovery system for anhydrous hydrogen fluoride production according to claim 3, characterized in that: The buffer tank (2) is equipped with a level gauge (16), and the level gauge (16) and the liquid phase transfer pump (9) are both connected to the control module (17).

5. The waste heat recovery system for anhydrous hydrogen fluoride production according to claim 1, characterized in that: The buffer tank (2) is equipped with a pressure safety valve (15) on top.

6. The waste heat recovery system for anhydrous hydrogen fluoride production according to claim 1, characterized in that: The raw material fluorosilicic acid inlet pipe (11) is equipped with a raw material fluorosilicic acid transfer pump (12).

7. The waste heat recovery system for anhydrous hydrogen fluoride production according to claim 1, characterized in that: The mixed gas output pipe (14) is equipped with a condenser (18), and the bottom of the condenser (18) is equipped with a condensate discharge pipe (19).

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