Sulfuric acid dechlorination system for chlor-alkali production

Abstract

The present disclosure relates to a sulfuric acid dechlorination system for chlor-alkali production, comprising a heating module, a dechlorination dilute sulfuric acid storage tank and an air blowing pipeline connected in communication, an air inlet end of the air blowing pipeline being connected with a compressed air source, an air outlet end of the air blowing pipeline being connected with a gas distributor arranged in the dechlorination dilute sulfuric acid storage tank; the heating module is used for heating at least part of the air blowing pipeline to make the compressed air in the air blowing pipeline reach a preset temperature. Through the above technical scheme, the sulfuric acid dechlorination system for chlor-alkali production can improve aeration uniformity and dechlorination efficiency.

Description

Technical Field

[0001] This disclosure relates to the field of chlor-alkali production technology, and more specifically, to a sulfuric acid dechlorination system for use in chlor-alkali production. Background Technology

[0002] During chlor-alkali production, a small amount of chlorine gas is absorbed into the dilute sulfuric acid solution from the chlorine drying process, forming chlorinated dilute sulfuric acid. Direct discharge or storage of this chlorinated dilute sulfuric acid not only causes equipment damage due to its strong corrosiveness but also renders it hazardous waste due to the toxicity of the free chlorine, requiring expensive professional treatment and wasting the resource value of the dilute sulfuric acid itself. Therefore, it is necessary to reduce the free chlorine content in the chlorinated dilute sulfuric acid to below a safe threshold, enabling its secondary utilization as a byproduct of sulfuric acid production.

[0003] Currently, air purging is commonly used to dechlorinate dilute sulfuric acid. Its core principle is to introduce compressed air into the dilute sulfuric acid, utilizing the gas-liquid contact process to strip free chlorine from the solution. However, traditional air purging technology has the following drawbacks: First, the aeration structure is too simple, often consisting of a single straight pipe directly introducing compressed air, resulting in uneven bubble distribution in the dilute sulfuric acid and limited gas-liquid contact area, severely restricting dechlorination efficiency. Second, the compressed air introduced is always at room temperature, which is insufficient for efficient dechlorination. These two drawbacks lead to low dechlorination efficiency. Utility Model Content

[0004] The purpose of this disclosure is to provide a sulfuric acid dechlorination system for chlor-alkali production that can improve aeration uniformity and dechlorination efficiency.

[0005] To achieve the above objectives, this disclosure provides a sulfuric acid dechlorination system for chlor-alkali production, comprising a heating module and a dechlorinated dilute sulfuric acid storage tank and an air purging pipeline connected in series. The air purging pipeline has an inlet connected to a compressed air source and an outlet connected to a gas distributor installed in the dechlorinated dilute sulfuric acid storage tank. The heating module is used to heat at least a portion of the air purging pipeline to bring the compressed air in the air purging pipeline to a preset temperature.

[0006] Optionally, the heating module includes a steam pipeline and a heating sleeve. The middle part of the air purging pipeline is provided with a heating section. The heating sleeve is sleeved on the heating section and forms a closed heating channel between the heating sleeve and the heating section. One end of the heating sleeve is provided with a steam inlet, which is connected to the steam pipeline. The other end of the heating sleeve is provided with a steam outlet, which is provided with a steam trap.

[0007] Optionally, the steam outlet is connected to a main discharge pipe, and the steam trap is installed at the end of the main discharge pipe away from the steam outlet. A secondary discharge pipe is also connected to the main discharge pipe, and a manual valve is installed on the secondary discharge pipe.

[0008] Optionally, the steam inlet is connected to the steam pipeline via a connecting pipe, the connecting pipe is equipped with a steam regulating valve, the heating section is equipped with a temperature detection element, the temperature detection element is electrically connected to the steam regulating valve, and both the temperature detection element and the steam regulating valve are signal-connected to the control unit to control the compressed air to be heated to the preset temperature.

[0009] Optionally, the length of the heating sleeve is 3m to 4m; the preset temperature is 60℃ to 65℃.

[0010] Optionally, the heating section and the heating sleeve are made of the same material, and their corresponding ends are sealed and welded; the part of the air purging pipeline located between the heating section and the gas distributor is made of CPVC (chlorinated polyvinyl chloride) and is equipped with a check valve.

[0011] Optionally, the gas distributor includes a main pipe and a plurality of branch pipes spaced apart along the length of the main pipe. The branch pipes are arranged at an angle to the main pipe. One end of the main pipe is connected to the air purging line, and the other end of the main pipe is closed. Both ends of the branch pipes are closed, and a plurality of air outlets are spaced apart on the branch pipes.

[0012] Optionally, the plurality of air outlets are evenly distributed, and the diameter of each air outlet is 1.5mm to 2.5mm.

[0013] Through the above technical solution, the sulfuric acid dechlorination system for chlor-alkali production disclosed herein adds a gas distributor to the traditional air blowing method. The gas distributor disperses the centrally introduced compressed air into multiple airflows, which allows the bubbles to diffuse evenly in the dilute sulfuric acid in the storage tank, thereby increasing the gas-liquid contact area and improving the dechlorination efficiency. At the same time, this disclosure adds a heating module, which heats the compressed air. The heated air can raise the local temperature of the dilute sulfuric acid and accelerate the transfer rate of free chlorine from the liquid phase to the gas phase. This works synergistically with the gas distributor to greatly improve the dechlorination efficiency and effect.

[0014] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Attached Figure Description

[0015] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic diagram of the structure of a sulfuric acid dechlorination system for chlor-alkali production provided in an embodiment of this disclosure; Figure 2 yes Figure 1 A magnified view of a section at point A in the middle; Figure 3 This is a schematic diagram of the installation of the heating sleeve provided in an embodiment of this disclosure; Figure 4 This is a schematic diagram of the structure of the gas distributor provided in an embodiment of this disclosure; Figure 5 This is a schematic diagram of the branch pipe of the gas distributor provided in an embodiment of this disclosure.

[0016] Explanation of reference numerals in the attached diagram: 1. Dechlorinated dilute sulfuric acid storage tank; 2. Air purging pipeline; 21. Air inlet; 22. Air outlet; 23. Heating section; 3. Gas distributor; 31. Main pipe; 32. Branch pipe; 321. Air outlet; 4. Steam pipeline; 41. Heating jacket; 411. Steam inlet; 412. Steam outlet; 42. Steam trap; 43. Main discharge pipe; 44. Secondary discharge pipe; 45. Manual valve; 46. Connecting pipe; 47. Steam regulating valve; 48. Main valve; 5. Check valve. Detailed Implementation

[0017] The specific embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this disclosure.

[0018] In the following description, when referring to the accompanying drawings, unless otherwise explained, the same reference numerals in different drawings denote the same or similar elements. The above definitions are for explanation and illustration only and should not be construed as limiting the present disclosure.

[0019] According to exemplary embodiments of this disclosure, reference is made to Figure 1 and Figure 2 As shown, a sulfuric acid dechlorination system for chlor-alkali production is provided, including a heating module and a dechlorinated dilute sulfuric acid storage tank 1 and an air purging pipeline 2 connected in series. The air inlet 21 of the air purging pipeline 2 is connected to a compressed air source, and the air outlet 22 of the air purging pipeline 2 is connected to a gas distributor 3 installed in the dechlorinated dilute sulfuric acid storage tank 1. The heating module is used to heat at least a portion of the air purging pipeline 2 so that the compressed air in the air purging pipeline 2 reaches a preset temperature.

[0020] Through the above technical solution, the sulfuric acid dechlorination system for chlor-alkali production disclosed herein adds a gas distributor 3 to the traditional air blowing method. The gas distributor 3 disperses the centrally introduced compressed air into multiple airflows, which allows the bubbles to diffuse evenly in the dilute sulfuric acid in the storage tank, thereby increasing the gas-liquid contact area and improving the dechlorination efficiency. At the same time, this disclosure adds a heating module, which heats the compressed air. The heated air can increase the local temperature of the dilute sulfuric acid and accelerate the transfer rate of free chlorine from the liquid phase to the gas phase. This works synergistically with the gas distributor 3 to greatly improve the dechlorination efficiency and dechlorination effect.

[0021] According to exemplary embodiments of this disclosure, referring to Figure 2 and Figure 3 As shown, the heating module includes a steam pipeline 4 and a heating sleeve 41. A heating section 23 is located in the middle of the air purging pipeline 2. The heating sleeve 41 is fitted onto the heating section 23, forming a sealed heating channel between them. One end of the heating sleeve 41 has a steam inlet 411 connected to the steam pipeline 4, and the other end has a steam outlet 412 equipped with a steam trap 42. In this technical solution, indirect heating via the heating sleeve 41 eliminates the need to modify the dechlorinated dilute sulfuric acid storage tank 1. Heating can be achieved simply by introducing steam using the existing steam pipeline 4, adapting to existing production equipment and reducing the difficulty and cost of modification.

[0022] In this disclosure, steam condenses into water after exchanging heat with compressed air in the heating channel. A steam trap 42 is provided to drain the condensate in a timely manner, ensuring that the heating channel is always filled with high-temperature steam, ensuring that the compressed air can stably absorb heat, and ensuring the steam heating efficiency.

[0023] According to exemplary embodiments of this disclosure, referring to Figure 2 As shown, steam outlet 412 is connected to a main discharge pipe 43. A steam trap 42 is installed at the end of the main discharge pipe 43 furthest from steam outlet 412. A secondary discharge pipe 44 is also connected to the main discharge pipe 43, and a manual valve 45 is installed on the secondary discharge pipe 44. With the above settings, during normal operation, the steam trap 42 is in the normally open state. When the steam trap 42 malfunctions and cannot drain water normally, or when the heating jacket 41 needs to be replaced or repaired, the manual valve 45 can be manually opened to drain the condensate, preventing condensate accumulation from affecting heating efficiency and improving system reliability.

[0024] According to exemplary embodiments of this disclosure, referring to Figure 2As shown, steam inlet 411 can be connected to steam pipeline 4 via connecting pipe 46. A steam regulating valve 47 can be installed on connecting pipe 46, and a temperature sensing element (not shown) can be installed on heating section 23. The temperature sensing element is electrically connected to the steam regulating valve 47, and both the temperature sensing element and the steam regulating valve 47 are signal-connected to the control unit to control the heating of compressed air to a preset temperature. In the above technical solution, the temperature sensing element can be a temperature sensor. The temperature sensing element collects the temperature data of the heated compressed air in real time and transmits the data to the control unit. If the temperature is lower than the preset value, the control unit sends a signal to increase the opening of the steam regulating valve 47, increasing the steam flow to raise the temperature; if the temperature is higher than the preset value, the control unit sends a signal to decrease the opening of the steam regulating valve 47 to reduce the steam flow. In this way, automatic and precise temperature control is achieved, ensuring the stability of the dechlorination process.

[0025] According to an exemplary embodiment of this disclosure, the length of the heating sleeve 41 is 3m to 4m; the preset temperature is 60℃ to 65℃. In the above technical solution, the sleeve length of 3m to 4m ensures that the compressed air has sufficient time to exchange heat with the steam in the heating section 23, and can just rise from room temperature to the preset temperature, ensuring that the compressed air is fully heated and meets the temperature requirements. For example, the length of the heating sleeve 41 can be set to 3m, 3.5m, or 4m; the dechlorination efficiency of dilute sulfuric acid at 60℃ to 65℃ can reach about 95%, which can effectively reduce the free chlorine content to the target threshold. For example, the preset temperature can be set to 60℃, 62℃, or 65℃.

[0026] According to an exemplary embodiment of this disclosure, the heating section 23 and the heating sleeve 41 can be made of the same material, and their corresponding ends are sealed and welded together. The portion of the air purging line 2 located between the heating section 23 and the gas distributor 3 is made of CPVC material and is equipped with a check valve 5. By sealing and welding the corresponding ends of the heating section 23 and the heating sleeve 41 together, the airtightness of the heating channel is ensured, steam leakage is prevented, and heating safety and efficiency are improved.

[0027] In this disclosure, the portion of the air purging pipeline 2 located between the heating section 23 and the gas distributor 3 is made of CPVC material. CPVC material has good corrosion resistance, can resist sulfuric acid erosion, and extend the service life of the pipeline. At the same time, a check valve 5 is installed on this part of the pipeline to prevent dilute sulfuric acid in the dechlorination dilute sulfuric acid storage tank 1 from flowing back into the heating section 23 of the air purging pipeline 2, thus avoiding corrosion of the heating section 23.

[0028] According to exemplary embodiments of this disclosure, referring to Figure 4 and Figure 5As shown, the gas distributor 3 includes a main pipe 31 and multiple branch pipes 32 spaced apart along the length of the main pipe 31. The branch pipes 32 are arranged at an angle to the main pipe 31. One end of the main pipe 31 is connected to the air purging line 2, and the other end of the main pipe 31 is closed. Both ends of the branch pipes 32 are closed, and multiple air outlets 321 are spaced apart on the branch pipes 32. Through the above arrangement, the gas distributor 3 forms a multi-stage flow distribution. Compressed air first enters the main pipe 31, then is evenly distributed to each branch pipe 32, and finally discharged through the air outlets 321 on the branch pipes 32. The branch pipes 32, arranged along the length of the main pipe 31, can cover the longitudinal area of ​​the storage tank, and the branch pipes 32, arranged at an angle to the main pipe 31, can cover the transverse area. Ultimately, this achieves uniform distribution of bubbles throughout the storage tank, increases the gas-liquid contact area, improves aeration uniformity, and further enhances dechlorination efficiency.

[0029] According to exemplary embodiments of this disclosure, referring to Figure 5 As shown, multiple vent holes 321 are evenly distributed, and the diameter of each vent hole 321 is 1.5mm to 2.5mm. The evenly distributed vent holes 321 can ensure that each branch pipe 32 can stably discharge bubbles and ensure that the bubbles diffuse evenly within the coverage area of ​​the branch pipe 32. The diameter of the vent holes 321 can be set to 1.5mm, 2mm or 2.5mm. They are small and not easy to clog. Furthermore, the specific surface area (surface area per unit volume) of the small bubbles is larger, resulting in a longer contact time with dilute sulfuric acid and a significantly increased probability of free chlorine stripping.

[0030] Reference Figures 1 to 5 As shown, the usage process of the sulfuric acid dechlorination system for chlor-alkali production disclosed in this invention is as follows: During dechlorination, dilute sulfuric acid containing chlorine is first injected into the dechlorination dilute sulfuric acid storage tank 1. Then, the main valve 48 of the steam pipeline 4 is opened, and the steam regulating valve 47 on the connecting pipe 46 is opened. High-temperature steam enters the sealed heating channel between the heating jacket 41 and the heating section 23 through the steam inlet 411 to preheat the flow space in the air blowing pipeline 2. The temperature detection element monitors the air temperature in the heating section 23 in real time and transmits the data to the control unit. When the temperature is below 60℃, the control unit sends a signal to automatically increase the opening of the steam regulating valve 47 to increase the steam flow and raise the temperature; when the temperature is above 65℃, the steam regulating valve 47 automatically decreases the opening to stabilize the temperature within the range of 60℃ to 65℃. During this process, the condensate generated after steam heat exchange flows into the main discharge pipe 43 through the steam outlet 412 and is automatically discharged by the steam trap 42 to ensure that the heating channel is full of steam. After the temperature in the heating section 23 stabilizes, the compressed air source is turned on and compressed air is introduced. The heated compressed air continues to flow through the CPVC pipeline section. Under the one-way protection of the check valve 5, it smoothly enters the gas distributor 3 in the dechlorinated dilute sulfuric acid storage tank 1. The compressed air first enters the main pipe 31 of the gas distributor 3, and then is evenly distributed to multiple branch pipes 32. Finally, it is dispersed into the chlorinated dilute sulfuric acid in the form of small bubbles through the air outlet 321 on the branch pipe 32. High-temperature, uniform bubbles rise slowly in dilute sulfuric acid, making full contact with the liquid and efficiently stripping free chlorine from the solution, which then escapes from the storage tank with the gas flow (it can be collected and treated through the tail gas recovery pipeline at the top of the storage tank), thus enabling the dechlorination reaction to continue.

[0031] The preferred embodiments of this disclosure have been described in detail above with reference to the accompanying drawings. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.

[0032] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0033] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. A sulfuric acid dechlorination system for chlor-alkali production, characterized in that, The device includes a heating module and a connected dechlorinated dilute sulfuric acid storage tank (1) and an air purging line (2). The air inlet (21) of the air purging line (2) is connected to a compressed air source, and the air outlet (22) of the air purging line (2) is connected to a gas distributor (3) installed in the dechlorinated dilute sulfuric acid storage tank (1). The heating module is used to heat at least a portion of the air purging line (2) so that the compressed air in the air purging line (2) reaches a preset temperature.

2. The sulfuric acid dechlorination system for chlor-alkali production according to claim 1, characterized in that, The heating module includes a steam pipeline (4) and a heating sleeve (41). The middle part of the air purging pipeline (2) is provided with a heating section (23). The heating sleeve (41) is sleeved on the heating section (23) and forms a closed heating channel with the heating section (23). One end of the heating sleeve (41) is provided with a steam inlet (411), which is connected to the steam pipeline (4). The other end of the heating sleeve (41) is provided with a steam outlet (412), which is provided with a steam trap (42).

3. The sulfuric acid dechlorination system for chlor-alkali production according to claim 2, characterized in that, The steam outlet (412) is connected to a main discharge pipe (43), and the steam trap (42) is installed at the end of the main discharge pipe (43) away from the steam outlet (412). A secondary discharge pipe (44) is also connected to the main discharge pipe (43), and a hand valve (45) is installed on the secondary discharge pipe (44).

4. The sulfuric acid dechlorination system for chlor-alkali production according to claim 3, characterized in that, The steam inlet (411) is connected to the steam pipeline (4) through the connecting pipe (46). The connecting pipe (46) is equipped with a steam regulating valve (47). The heating section (23) is equipped with a temperature detection element. The temperature detection element is electrically connected to the steam regulating valve (47). Both the temperature detection element and the steam regulating valve (47) are signal connected to the control unit to control the compressed air to be heated to the preset temperature.

5. The sulfuric acid dechlorination system for chlor-alkali production according to claim 4, characterized in that, The length of the heating sleeve (41) is 3m to 4m; the preset temperature is 60℃ to 65℃.

6. The sulfuric acid dechlorination system for chlor-alkali production according to claim 5, characterized in that, The heating section (23) and the heating sleeve (41) are made of the same material, and their corresponding ends are sealed and welded; the part of the air purging pipeline (2) between the heating section (23) and the gas distributor (3) is made of CPVC material and is equipped with a check valve (5).

7. The sulfuric acid dechlorination system for chlor-alkali production according to any one of claims 1 to 6, characterized in that, The gas distributor (3) includes a main pipe (31) and a plurality of branch pipes (32) arranged at intervals along the length of the main pipe (31). The branch pipes (32) are arranged at an angle to the main pipe (31). One end of the main pipe (31) is connected to the air purging line (2), and the other end of the main pipe (31) is closed. Both ends of the branch pipes (32) are closed, and a plurality of air outlets (321) are spaced apart on the branch pipes (32).

8. The sulfuric acid dechlorination system for chlor-alkali production according to claim 7, characterized in that, The plurality of air outlets (321) are evenly distributed, and the diameter of each air outlet (321) is 1.5mm to 2.5mm.

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