Chlorine cooling and dust removing device and method for magnesium electrolysis production

Abstract

The invention discloses a chlorine gas cooling and dust removing device and method for magnesium electrolysis production. The invention discloses a chlorine cooling and dust removing device for magnesium electrolysis production. The chlorine cooling and dust removing device comprises a desuperheater, a chlorine washing tower, a refrigerant heat exchange system, a gas-liquid separator and an acid mud treatment system, the high-temperature chlorine enters a desuperheater to be cooled to a certain temperature and then enters a chlorine washing tower to be washed, the washed chlorine mixed with refrigerant liquid enters a gas-liquid separator, the separated low-temperature chlorine is discharged, and the separated refrigerant liquid enters the chlorine washing tower again; the used refrigerant is cooled by the refrigerant heat exchange system, and the cooled refrigerant enters the chlorine washing tower and the desuperheater again; acid mud at the bottom of the washing tower is discharged after passing through an acid mud treatment system. The equipment configuration can be simplified, and meanwhile, the deep purification and resource utilization of the high-temperature dust-containing chlorine can be realized, so that the production bottleneck is broken through, and the increasingly strict environmental protection requirement is met.

Description

Technical Field

[0001] The present invention relates to a chlorine gas cooling and dust removal device and method for magnesium electrolysis production, belonging to the technical field of electrolytic magnesium. Background Art

[0002] Magnesium metal and magnesium alloys are widely used in fields such as aerospace, military, transportation, and 3C products. The lightweight manufacturing of equipment has brought significant opportunities for the large-scale use of magnesium metal and magnesium alloys. At present, domestic titanium sponge enterprises and foreign electrolytic magnesium enterprises both use multi-polar magnesium electrolytic cells in production. This process uses anhydrous magnesium chloride particles as raw materials and adds them to a multi-polar magnesium electrolytic cell to electrolyze and produce molten magnesium and chlorine gas. During the electrolysis process, the temperature of the chlorine gas generated at the anode of the electrolytic cell is about 400 - 450°C, and it usually contains electrolyte sublimates, with a dust content of about 30 g / Nm3. The chlorine gas comes out of the electrolytic cell gas collection hood, is collected through chlorine gas branch pipes and converges into the chlorine gas main pipe, then enters the chlorine gas purification system through a bag filter, and is subsequently sent to the required users.

[0003] In actual production, the temperature at the chlorine gas branch pipes and the main pipe is about 300°C, and the temperature at the bag filter is about 200°C. And the sublimates in the system need to be cleaned once a month on average. Workers can only judge whether there are over-temperature and blockage conditions based on on-site temperature measurement and experience, which poses risks of chlorine gas leakage and fire caused by temperature rise, posing great potential hazards to the operation of the entire factory. At present, the chlorine gas treatment process in the magnesium electrolysis industry can basically meet the goal of absorbing moisture and dust in chlorine gas, but it requires a lot of equipment, consumes a large amount of sulfuric acid, and has a relatively high dust content. Long-term flow of high-temperature chlorine gas through pipelines and equipment is likely to cause aging of sealing materials and cracking of welds, resulting in chlorine gas leakage and threatening personnel safety; the electrolyte sublimates entrained in the chlorine gas deposit on the inner wall of the equipment, forming acid sludge, which needs to be manually cleaned every month, with a harsh operating environment and a fire risk; and when the acid sludge is not treated thoroughly, residual chloride ions and acidic substances in the discharged wastewater are likely to cause soil and water pollution. Summary of the Invention

[0004] The purpose of the present invention is to provide a chlorine gas cooling and dust removal device and method for magnesium electrolysis production, which can achieve deep purification and resource utilization of high-temperature dust-containing chlorine gas while simplifying equipment configuration, so as to break through production bottlenecks and meet increasingly strict environmental protection requirements.

[0005] The technical solution adopted by the present invention is as follows:

[0006] A chlorine gas cooling and dust removal device for magnesium electrolysis production, comprising a temperature reducer, a chlorine gas scrubbing tower, a refrigerant heat exchange system, a gas-liquid separator, and a sludge treatment system; wherein, the chlorine gas outlet of the temperature reducer is connected to the chlorine gas inlet of the chlorine gas scrubbing tower, and the acid sludge outlet of the chlorine gas scrubbing tower is connected to the inlet of the acid sludge treatment system; the outlet of the acid sludge treatment system is discharged externally; the refrigerant outlet of the chlorine gas scrubbing tower is connected to the inlet of the refrigerant heat exchange system; the refrigerant outlet of the refrigerant heat exchange system is respectively connected to the refrigerant inlets of the temperature reducer and the chlorine gas scrubbing tower; the chlorine gas outlet of the chlorine gas scrubbing tower is connected to the gas-liquid separator; the gas outlet of the gas-liquid separator is discharged externally; the liquid outlet of the gas-liquid separator is connected to the refrigerant inlet of the chlorine gas scrubbing tower.

[0007] Optionally, a demisting filter element is adopted inside the gas-liquid separator.

[0008] Optionally, the refrigerant heat exchange system includes a scrubbing tower circulation pump and a refrigerant heat exchanger arranged in sequence, and a refrigerant supplement branch is also connected downstream of the refrigerant heat exchanger. After the downstream of the refrigerant heat exchanger and the refrigerant supplement branch converge, they flow to the refrigerant inlets of the temperature reducer and the chlorine gas scrubbing tower.

[0009] Optionally, the refrigerant heat exchanger is a spiral plate heat exchanger.

[0010] Optionally, the chlorine gas inlet, acid sludge outlet, and refrigerant outlet of the chlorine gas scrubbing tower are arranged at the bottom, and the chlorine gas outlet of the chlorine gas scrubbing tower is arranged at the top.

[0011] Optionally, the refrigerant inlet of the chlorine gas scrubbing tower is arranged at the upper part; or, the refrigerant inlet of the chlorine gas scrubbing tower includes a first inlet at the upper part and a second inlet at the middle part. The refrigerant outlet of the refrigerant heat exchange system is connected to the first inlet, and the liquid outlet of the gas-liquid separator is connected to the second inlet.

[0012] Optionally, the acid sludge treatment system includes a dust-containing refrigerant dissolution tank, a neutralization tank, and a sludge discharge pump arranged in sequence.

[0013] Optionally, nitrogen is introduced into the dust-containing refrigerant dissolution tank.

[0014] Optionally, caustic soda solution is introduced into the neutralization tank.

[0015] A chlorine gas cooling and dust removal method for magnesium electrolysis production, comprising the following processes:

[0016] S1. High-temperature chlorine gas enters the temperature reducer to reduce the temperature by a certain degree and then enters the chlorine gas scrubbing tower for scrubbing. The scrubbed chlorine gas is mixed with the refrigerant liquid and enters the gas-liquid separator. The separated low-temperature chlorine gas is discharged externally, and the separated refrigerant liquid re-enters the chlorine gas scrubbing tower.

[0017] S2. The used refrigerant is cooled through the refrigerant heat exchange system, and the cooled refrigerant re-enters the chlorine scrubbing tower and the desuperheater;

[0018] S3. The acid sludge at the bottom of the scrubbing tower is discharged externally after passing through the acid sludge treatment system.

[0019] In summary, due to the adoption of the above technical solutions, the beneficial effects of the present invention are as follows:

[0020] 1. The chlorine gas cooling and dust removal device and method for magnesium electrolysis production provided by the present invention adopt a tower-type circulating cooling and refrigerant recycling process, that is: the scrubbing tower + high-efficiency spiral plate heat exchanger process. The high-temperature dust-containing chlorine gas removes moisture and dust while being cooled in the scrubbing tower; the high-temperature refrigerant is cooled by circulating water in the spiral plate heat exchanger and is circulated back to the scrubbing tower for use, reducing production costs.

[0021] 2. The chlorine gas cooling and dust removal device and method for magnesium electrolysis production provided by the present invention are provided with a desuperheater on the high-temperature chlorine gas pipeline. The low-temperature refrigerant is used for pre-cooling to protect the scrubbing tower from being damaged by high temperature; the acid sludge neutralization treatment and recovery process for the scrubbing tower uses nitrogen gas to strip chlorine gas, and the caustic soda solution neutralizes the acid sludge to meet the external discharge requirements.

[0022] 3. The chlorine gas cooling and dust removal device and method for magnesium electrolysis production provided by the present invention achieve the functions of dust removal, dehumidification and cooling for high-temperature dust-containing chlorine gas, and at the same time treat the generated solid waste, which can significantly save fixed asset investment and utility consumption. It has strong engineering practicability. Description of the Drawings

[0023] Figure 1 is the process schematic diagram of the present invention.

[0024] Reference numerals in the figure: 1 - chlorine scrubbing tower, 2 - refrigerant heat exchanger, 3 - gas-liquid separator, 4 - desuperheater, 5 - dust-containing refrigerant dissolution tank, 6 - neutralization tank, 7 - scrubbing tower circulation pump, 8 - sludge external discharge pump. Detailed Embodiments

[0025] The following will describe the present invention in detail with reference to the drawings.

[0026] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0027] A chlorine gas cooling and dust removal device for magnesium electrolysis production, as Figure 1As shown in the figure, it includes a desuperheater 4, a chlorine scrubbing tower 1, a refrigerant heat exchange system, a gas-liquid separator 3, and an acid sludge treatment system. Among them, the chlorine outlet of the desuperheater 4 is connected to the chlorine inlet of the chlorine scrubbing tower 1, and the acid sludge outlet of the chlorine scrubbing tower 1 is connected to the inlet of the acid sludge treatment system; the outlet of the acid sludge treatment system is discharged to the outside; the refrigerant outlet of the chlorine scrubbing tower 1 is connected to the inlet of the refrigerant heat exchange system; the refrigerant outlet of the refrigerant heat exchange system is respectively connected to the refrigerant inlets of the desuperheater 4 and the chlorine scrubbing tower 1; the chlorine outlet of the chlorine scrubbing tower 1 is connected to the gas-liquid separator 3; the gas outlet of the gas-liquid separator 3 is discharged to the outside; the liquid outlet of the gas-liquid separator 3 is connected to the refrigerant inlet of the chlorine scrubbing tower 1.

[0028] In this solution, the desuperheater 4 pre-cools the chlorine before it enters the scrubbing tower, reducing the initial temperature, avoiding direct impact of high temperature on the scrubbing tower, prolonging the equipment life, and creating suitable conditions for subsequent cooling and dust removal at the same time. The chlorine scrubbing tower 1 realizes the integration of cooling, dust removal, and dehumidification through countercurrent contact between refrigerant spraying and chlorine. Among them, a spraying system and a packing layer are arranged inside the chlorine scrubbing tower 1 to optimize the gas-liquid contact efficiency; corrosion-resistant materials are used to adapt to the acidic environment. The refrigerant heat exchange system cools the refrigerant flowing out of the scrubbing tower and recirculates it back to the scrubbing tower and the desuperheater 4 for use. The gas-liquid separator 3 separates the liquid droplets and dust entrained in the treated chlorine to ensure that the purity of the outlet gas meets the standards. The acid sludge treatment system collects the acid sludge at the bottom of the scrubbing tower, realizes the resource utilization and harmless discharge of solid waste, and avoids environmental pollution. This device integrates temperature reduction, dust removal, dehumidification, and acid sludge treatment, replaces traditional multi-stage equipment, simplifies the process flow, reduces the floor area and investment cost. Concentrating the functions of multiple links in a single device reduces the equipment investment and operation and maintenance complexity, breaking through the low-efficiency bottleneck of traditional multi-stage treatment. Through the closed-loop process of pre-cooling protection, deep purification of the scrubbing tower, recycling of refrigerant, and harmless treatment of acid sludge, it solves the pain points of complex equipment, high energy consumption, and high environmental protection risks in traditional magnesium electrolysis chlorine treatment. The staged temperature reduction and dust removal and resource recycling have high efficiency, economy, and environmental protection, and are suitable for industrial purification scenarios of high-temperature and highly corrosive dust-containing gases.

[0029] As another specific implementation manner, an atomization removal filter element is adopted inside the gas-liquid separator 3. The atomization removal filter element intercepts fine liquid droplets and dust through a multi-layer fiber or metal wire mesh structure, significantly improving the gas-liquid separation efficiency and ensuring that the moisture content and dust content of the outlet chlorine meet the standards stably. The modular installation of the filter element is convenient for quick replacement or cleaning, reducing the downtime for maintenance; at the same time, the separated liquid flows back to the scrubbing tower through the bottom for recycling, reducing the refrigerant consumption and forming a closed-loop management of resources. This design takes into account the purification accuracy, equipment durability, and operation economy, ensuring the long-term stable operation of the system.

[0030] As another specific implementation, the refrigerant heat exchange system includes a washing tower circulation pump 7 and a refrigerant heat exchanger 2, which are arranged in sequence. The downstream of the refrigerant heat exchanger 2 is also connected to a refrigerant supplementary branch, and the downstream of the refrigerant heat exchanger 2 and the refrigerant supplementary branch merge to flow to the refrigerant inlet of the desuperheater 4 and the chlorine washing tower 1. The circulation pump ensures that the refrigerant continues to flow between the washing tower and the heat exchanger, thereby improving the heat exchange efficiency; the refrigerant heat exchanger 2 quickly cools the refrigerant through circulating water to reduce the refrigerant consumption; the supplementary branch can replenish the refrigerant in real time according to the refrigerant loss, maintain the system concentration and flow balance, and avoid process fluctuations caused by insufficient refrigerant. At the same time, after the refrigerant merges, it is divided into a branch to supply the desuperheater 4 and the washing tower, which not only ensures the pre-cooling effect of the desuperheater 4, but also meets the spraying requirements of the washing tower, forming a collaboratively optimized refrigerant distribution mechanism, and significantly reducing energy consumption and operation and maintenance costs.

[0031] As another specific implementation, the refrigerant heat exchanger 2 is a spiral plate heat exchanger. The spiral plate heat exchanger greatly increases the heat transfer area through the multi-layer corrugated plate design, and combines the reverse flow of the refrigerant and the circulating water to significantly improve the heat exchange efficiency and quickly cool the high-temperature refrigerant to the target temperature. With the refrigerant circulation pump and the supplementary branch, the system can dynamically balance the refrigerant flow and temperature, ensure the continuous and stable cooling process, reduce energy consumption and operating costs, and meet the efficient and reliable requirements of high-temperature chlorine treatment.

[0032] As another specific implementation, the chlorine inlet, acid sludge outlet and refrigerant outlet of the chlorine scrubber 1 are arranged at the bottom, and the chlorine outlet of the chlorine scrubber 1 is arranged at the top. After entering from the bottom, the chlorine flows upward, and forms a countercurrent contact with the refrigerant sprayed down from the top, prolonging the gas-liquid contact time and increasing the mass transfer area, significantly improving the cooling, dust removal and dehumidification efficiency; the acid sludge and refrigerant naturally settle to the bottom due to gravity and are discharged in a centralized manner, avoiding accumulation and blockage in the tower and reducing the maintenance frequency; the top chlorine outlet uses the characteristic of reduced gas density after purification to smoothly export qualified chlorine, and at the same time, in combination with the gas-liquid separator 3, further removes entrained droplets to ensure the purity of the exhaust gas.

[0033] As another specific embodiment, the refrigerant inlet of the chlorine scrubbing tower 1 is arranged at the upper part; alternatively, the refrigerant inlet of the chlorine scrubbing tower 1 includes a first inlet at the upper part and a second inlet at the middle part. The refrigerant outlet of the refrigerant heat exchange system is connected to the first inlet, and the liquid outlet of the gas-liquid separator 3 is connected to the second inlet. When the refrigerant inlet is only arranged at the upper part, the refrigerant is evenly sprayed from top to bottom and contacts the chlorine gas entering from the bottom in a countercurrent manner, maximizing the mass transfer area and enhancing the cooling and dust removal effects; after adding the second inlet in the middle part, the separated and recycled refrigerant can be supplemented from the middle part, specifically enhancing the treatment intensity of the chlorine gas in the middle section, avoiding the problem of uneven distribution caused by the gravitational settlement of the upper refrigerant, reducing the fresh refrigerant supplement amount at the same time, and reducing the operating cost. Both configurations optimize the temperature and concentration gradients in the tower by injecting the refrigerant in stages, adapt to different working conditions, and balance the treatment efficiency and resource recycling.

[0034] As another specific embodiment, the acid sludge treatment system includes a dust-containing refrigerant dissolution tank 5, a neutralization tank 6 and a sludge discharge pump 8 arranged in sequence. The dust-containing refrigerant dissolution tank 5 separates the residual chlorine in the acid sludge and recycles it to the waste gas system, reducing the emission of toxic gases; the solution in the neutralization tank 6 converts acidic substances such as sulfuric acid and magnesium chloride in the acid sludge into neutral salts to ensure that the pH value of the discharged wastewater meets the standard; the sludge discharge pump 8 stably transports the neutralized sludge to the disposal link to avoid the risk of manual cleaning.

[0035] As another specific embodiment, nitrogen is connected to the dust-containing refrigerant dissolution tank 5. The acid sludge at the bottom of the scrubbing tower enters the dust-containing refrigerant dissolution tank 5, and the residual chlorine is separated by nitrogen stripping and recycled to the waste gas treatment system to eliminate the leakage risk.

[0036] As another specific embodiment, a caustic soda solution is connected to the neutralization tank 6. The acid sludge after stripping reacts with the caustic soda solution in the neutralization tank 6 to generate neutral salts, making the pH value of the discharged waste brine and the heavy metal content of the sludge meet the standards.

[0037] A method for cooling and dedusting chlorine gas used in magnesium electrolysis production includes the following processes:

[0038] S1. High-temperature chlorine gas enters the desuperheater 4 to reduce the temperature by a certain amount and then enters the chlorine scrubbing tower 1 for scrubbing. The scrubbed chlorine gas is mixed with the refrigerant liquid and enters the gas-liquid separator 3. The separated low-temperature chlorine gas is discharged, and the separated refrigerant liquid re-enters the chlorine scrubbing tower 1; the high-temperature chlorine gas above 200 °C is first cooled by the refrigerant spray of the desuperheater 4 to about 70 °C. The purified chlorine gas removes the residual liquid droplets through the gas-liquid separator 3. The inside of the gas-liquid separator 3 adopts a demisting filter element to ensure that the moisture content, dust content and temperature of the outlet chlorine gas can be reduced to within 10 ppm, 30 mg / Nm3 and 50 °C respectively.

[0039] S2. The used refrigerant is cooled by the refrigerant heat exchange system, and the cooled refrigerant re-enters the chlorine scrubbing tower 1 and the desuperheater 4; the cooled chlorine gas enters the scrubbing tower and contacts the circulating refrigerant countercurrently to be further cooled to below 50°C, while removing dust and moisture. The refrigerant heat exchange system uses a spiral plate heat exchanger and is cooled by circulating water to reduce the refrigerant temperature to about 60°C.

[0040] S3. The acid sludge at the bottom of the scrubbing tower is discharged after being treated by the acid sludge treatment system. After the chlorine gas is recovered by air stripping from the acid sludge at the bottom of the scrubbing tower, it is neutralized and treated into harmless salts for external discharge.

[0041] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. The present invention extends to any new feature or any new combination disclosed in this specification, and any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A chlorine gas cooling and dust removal device for magnesium electrolysis production, characterized in that: It includes a desuperheater (4), a chlorine gas scrubbing tower (1), a refrigerant heat exchange system, a gas-liquid separator (3) and a sludge treatment system; wherein, the chlorine gas outlet of the desuperheater (4) is connected to the chlorine gas inlet of the chlorine gas scrubbing tower (1), and the acid sludge outlet of the chlorine gas scrubbing tower (1) is connected to the inlet of the acid sludge treatment system; the outlet of the acid sludge treatment system is discharged externally; the refrigerant outlet of the chlorine gas scrubbing tower (1) is connected to the inlet of the refrigerant heat exchange system; the refrigerant outlet of the refrigerant heat exchange system is respectively communicated with the refrigerant inlets of the desuperheater (4) and the chlorine gas scrubbing tower (1); the chlorine gas outlet of the chlorine gas scrubbing tower (1) is connected to the gas-liquid separator (3); the gas outlet of the gas-liquid separator (3) is discharged externally; the liquid outlet of the gas-liquid separator (3) is communicated with the refrigerant inlet of the chlorine gas scrubbing tower (1).

2. The chlorine gas cooling and dust removal device for magnesium electrolysis production according to claim 1, characterized in that: The inside of the gas-liquid separator (3) uses a demisting filter element.

3. The chlorine gas cooling and dust removal device for magnesium electrolysis production according to claim 1, wherein: The refrigerant heat exchange system includes a scrubbing tower circulation pump (7) and a refrigerant heat exchanger (2) arranged in sequence. A refrigerant replenishment branch is also communicated downstream of the refrigerant heat exchanger (2). After the downstream of the refrigerant heat exchanger (2) and the refrigerant replenishment branch converge, they flow to the refrigerant inlets of the desuperheater (4) and the chlorine gas scrubbing tower (1).

4. The chlorine gas cooling and dust removal device for magnesium electrolysis production according to claim 3, characterized in that: The refrigerant heat exchanger (2) is a spiral plate heat exchanger.

5. The chlorine gas cooling and dust removal device for magnesium electrolysis production according to claim 1, characterized in that: The chlorine gas inlet, acid sludge outlet and refrigerant outlet of the chlorine gas scrubbing tower (1) are arranged at the bottom, and the chlorine gas outlet of the chlorine gas scrubbing tower (1) is arranged at the top.

6. The chlorine gas cooling and dust removal device for magnesium electrolysis production according to claim 1, wherein: The refrigerant inlet of the chlorine gas scrubbing tower (1) is arranged at the upper part; or, the refrigerant inlet of the chlorine gas scrubbing tower (1) includes a first inlet at the upper part and a second inlet in the middle. The refrigerant outlet of the refrigerant heat exchange system is communicated with the first inlet, and the liquid outlet of the gas-liquid separator (3) is communicated with the second inlet.

7. The chlorine gas cooling and dust removal device for magnesium electrolysis production according to claim 1, characterized in that: The acid sludge treatment system includes a dust-containing refrigerant dissolution tank (5), a neutralization tank (6) and a sludge discharge pump (8) arranged in sequence.

8. The chlorine gas cooling and dust removal device for magnesium electrolysis production according to claim 7, characterized in that: Nitrogen is introduced into the dust-containing refrigerant dissolution tank (5).

9. The chlorine gas cooling and dust removal device for magnesium electrolysis production according to claim 7, characterized in that: Caustic soda solution is introduced into the neutralization tank (6).

10. A method for cooling and dust removal of chlorine gas for magnesium electrolysis production, including the following processes: S1. High-temperature chlorine gas enters the desuperheater (4) to reduce the temperature by a certain amount and then enters the chlorine gas scrubbing tower (1) for washing. The washed chlorine gas is mixed with the refrigerant liquid and enters the gas-liquid separator (3). The separated low-temperature chlorine gas is discharged externally, and the separated refrigerant liquid re-enters the chlorine gas scrubbing tower (1); S2. The used refrigerant is cooled through the refrigerant heat exchange system, and the cooled refrigerant re-enters the chlorine gas scrubbing tower (1) and the desuperheater (4); S3. The acid sludge at the bottom of the scrubbing tower is discharged externally after passing through the acid sludge treatment system.

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