Zero-discharge device and process for double-layer liquid seal, redundant chlorine capture, siphon pure discharge and closed-loop electrolysis of sodium metal

Abstract

The invention discloses a zero-discharge device and process for double-layer liquid sealing, redundant chlorine capturing, siphon pure discharge and closed-loop electrolysis of metal sodium, and belongs to the technical field of metal sodium preparation. The device comprises a furnace body, an oxygen-isolating anti-explosion inert liquid seal layer, a chlorine capture liquid seal layer, a liquid metal sodium layer, a molten sodium chloride electrolysis layer, a siphon type pure sodium discharge structure and an automatic feeding control system, the double-layer liquid seal is adopted to realize oxygen isolation, explosion prevention and chlorine in-situ absorption, the chlorine absorption capacity is designed to be more than two times of the maximum chlorine yield, and no leakage is ensured; liquid sodium is driven by lifting the liquid level during feeding to trigger siphon discharge, only pure metal sodium is produced, entrainment is avoided, and the purity is high; reaction byproducts are converted into raw materials to be recycled, no waste gas, no waste residues and no waste liquid exist in the whole process, and the byproduct water vapor can be condensed into purified water to be utilized. The device is simple in structure, intrinsically safe, high in automation degree, environmentally friendly and suitable for continuous production of high-purity metal sodium.

Description

Technical Field

[0001] This invention belongs to the field of molten electrolytic preparation of metallic sodium, specifically relating to a metallic sodium production device and process with double-layer liquid seal, redundant chlorine gas capture, feeding and sodium driving, siphon pure discharge, closed-loop raw material circulation, fully unmanned operation, and zero waste. Background Technology

[0002] Traditional electrolysis of molten sodium chloride to produce metallic sodium has the following drawbacks: 1. Electrolysis produces highly toxic chlorine gas as a byproduct, requiring a complex recovery and treatment system, posing extremely high safety and environmental risks; 2. Liquid sodium is easily oxidized, burned, and exploded upon contact with air, resulting in poor safety; 3. Conventional overflow discharge of sodium easily carries molten salt, leading to low product purity; 4. The equipment is complex, energy-intensive, and labor-intensive, and generates waste gas, waste residue, and waste liquid emissions; 5. There is no redundant design for chlorine absorption, posing a potential leakage hazard. Summary of the Invention

[0003] 1. Purpose of the invention: To overcome all the shortcomings of the prior art and provide an intrinsically safe, zero waste gas, zero waste residue, zero waste liquid, high sodium purity, fully automatic and continuous sodium production device and process.

[0004] 2. Equipment Structure: The furnace body is made of high-purity low-carbon steel or pure iron, resistant to sodium penetration and free from impurities and side reactions. The furnace interior forms a four-layer stable liquid phase structure from top to bottom: 1. First Layer: Oxygen-barrier and explosion-proof inert liquid seal layer. Low-density, high-temperature resistant, chemically inert molten salt, used to isolate external air, prevent explosions, and prevent sodium oxidation combustion. 2. Second Layer: Chlorine capture reaction liquid seal layer. Molten sodium hydroxide (NaOH), used to absorb chlorine in situ and convert it into sodium chloride for reflux electrolysis. Designed absorption capacity ≥ twice the maximum chlorine production rate, achieving redundant and safe chlorine capture. 3. Third Layer: Liquid metallic sodium layer. Pure liquid sodium generated by electrolysis. 4. Fourth Layer: Molten sodium chloride electrolysis layer. Main electrolysis raw material area, providing the molten sodium chloride required for electrolysis. Key Equipment: Automatic sodium chloride feeding mechanism, automatic sodium hydroxide feeding mechanism, siphon-type pure sodium discharge structure, liquid level and temperature monitoring and fully automatic control system. 3. Process Principle: 1. Electrolysis Reaction: 2NaCl electrolysis → 2Na + Cl2↑. 2. Chlorine Redundancy Capture: Cl2 + 2NaOH → NaCl + NaClO + H2O. At high temperature, NaClO further decomposes into NaCl and O2, ultimately converting entirely into sodium chloride which settles back into the electrolytic layer for recycling. 3. Sodium Feeding and Discharge: By adding sodium chloride or sodium hydroxide, the overall liquid level inside the furnace is raised, forcing liquid sodium to the siphon height. 4. Pure Sodium Siphon Discharge: Once the liquid sodium reaches the set level, a siphon is triggered, extracting only pure liquid sodium without carrying away lower molten salt, ensuring high purity of the sodium product. 5. Intelligent Feeding: Sodium hydroxide is added when the sodium hydroxide liquid seal layer is insufficient; sodium chloride is added when the liquid seal is normal, achieving continuous and stable system operation.

[0005] 4. Advantages of the Invention: 1. Double-layer liquid seal for double safety: the upper layer is oxygen-proof and explosion-proof, while the lower layer provides redundant chlorine capture, eliminating safety risks at the source; 2. Chlorine absorption capacity ≥ 2 times the chlorine production capacity, ensuring 100% absorption of chlorine with no leakage or overflow; 3. The siphon-type sodium discharge structure discharges only pure sodium, without entraining molten salt, resulting in high product purity; 4. Automatic sodium removal by raising the liquid level during feeding, requiring no pumps or mechanical power, resulting in a simple and reliable structure; 5. Closed-loop raw material circulation, with a utilization rate close to 100% and no waste residue generated; 6. Zero waste gas and zero waste liquid throughout the process; byproduct water vapor can be condensed into clean water for reuse; 7. Fully automatic unmanned operation, simple operation, low labor costs, and strong stability; 8. Excellent environmental performance, allowing for rapid approval of environmental and safety assessments. Attached Figure Description

[0006] Figure 1 The following is a schematic diagram of the device structure of the present invention: 1. Furnace body; 2. Oxygen-proof and explosion-proof inert liquid seal layer; 3. Chlorine capture liquid seal layer; 4. Liquid metallic sodium layer; 5. Molten sodium chloride electrolysis layer; 6. Siphon-type pure sodium discharge structure; 7. Sodium chloride feed port; 8. Sodium hydroxide feed port; 9. Automatic control system.

Claims

1. A zero-emission device for double-layer liquid seal, redundant chlorine capture, siphon pure discharge, and closed-loop electrolysis of metallic sodium, characterized in that, The furnace body comprises, from top to bottom: an oxygen-barrier explosion-proof inert liquid seal layer, a sodium hydroxide chlorine capture liquid seal layer, a liquid metallic sodium layer, and a molten sodium chloride electrolysis layer; the chlorine absorption capacity of the chlorine capture liquid seal layer is not less than twice the maximum electrolytic chlorine production rate; the device is equipped with a siphon-type pure sodium discharge structure.

2. The apparatus according to claim 1, characterized in that, By adding sodium chloride or sodium hydroxide into the furnace to raise the liquid level, the liquid sodium is forced to the siphon port, and the pure sodium is discharged using the siphon effect.

3. The apparatus according to claim 1, characterized in that, Chlorine gas is absorbed by sodium hydroxide and converted into sodium chloride, which then settles back into the electrolytic layer for recycling.

4. A zero-emission production process based on the device described in claim 1, characterized in that, include: Electrolysis of sodium chloride produces sodium and chlorine gas; the chlorine gas is redundantly absorbed by sodium hydroxide and converted into sodium chloride for reflux; feeding raises the liquid level and triggers a siphon to discharge pure sodium. The system only replenishes sodium chloride and sodium hydroxide, and produces no waste gas, no waste residue, and no waste liquid.

Images