Coal Mine Thermal Damage Prevention and Control

1. The air temperature in underground mining areas and electromechanical chambers must comply with the current "Coal Mine Safety Regulations." This ensures a safe and healthy working environment for miners.

2. When designing new mines or expanding existing ones, temperature forecasting methods should be applied based on geological reports from well field exploration and information provided by the construction company. This helps in planning effective cooling strategies in advance.

3. In mines where temperatures exceed acceptable limits, comprehensive cooling measures must be implemented to maintain safe conditions and prevent heat-related health issues among workers.

4. Non-artificial cooling methods should be used when appropriate, leveraging natural cooling sources such as increased airflow, local wind speed enhancement in work zones, or down ventilation. These strategies help reduce heat without relying on artificial systems. Additionally, avoiding heat sources, insulating equipment, and managing hot water are essential steps in maintaining a cooler underground environment.

5. Artificial cooling solutions should be chosen based on specific mine conditions, including geological structure, ventilation systems, cooling requirements, and available water resources. After thorough technical and economic analysis, options like mobile underground air conditioning, compressed air cooling, or centralized ground-based systems may be adopted to ensure efficient and sustainable cooling.

6. Underground air treatment systems must meet the following standards:

• (1) Air treatment equipment should be selected based on the volume of air to be treated and the cooling load, using direct evaporative coolers, water-cooled surface units, spray chillers, or spray chambers.
• (2) Air treatment can be centralized or handled at each cooling location depending on the situation.
• (3) If the air volume is large, the cooling load is high, or the temperature difference exceeds 10°C, a combined approach may be more effective and economical.
• (4) The air volume processed by the system should not exceed the supply air volume. For working faces, it should not exceed 70% of the total air volume at the site.

7. The condensing heat removal method for chillers should consider factors like cooling mode, condensation heat, water quality, and mine conditions. The following guidelines apply:

• (1) Cooling towers or natural water bodies can be used for ground-level heat dissipation.
• (2) If an underground centralized air conditioning system is used, underground water should be prioritized for condensation heat removal if suitable. Otherwise, mine return air or cooled groundwater may be used.
• (3) When using return air for heat removal, the wet bulb temperature should not exceed 29°C to ensure efficiency and safety.

8. Refrigerants must meet fire safety, non-explosive, non-toxic, and environmentally friendly standards. They should also have high condensing temperatures and low condensing pressures for optimal performance.

9. The cold load backup factor for chillers should range between 110% and 120%. At least two refrigeration units should be installed. For large cooling loads, large-scale chillers are recommended to ensure reliability and efficiency.

10. If the refrigeration station is located on the ground, its design and layout must follow the national standard GB 50019 for heating, ventilation, and air conditioning. The station should be at least 50 meters away from the air inlet and positioned downwind during summer to optimize performance.

11. For underground refrigeration stations, the location and layout should facilitate efficient cooling, heat removal, and ease of equipment handling, installation, maintenance, and operation while ensuring worker safety.

12. In mines deeper than 600 meters, a coupling device must be installed to transfer cold from the ground-based air conditioning system. The coupling method should prioritize safety, energy efficiency, and ease of maintenance. Options like shell-and-tube heat exchangers or multi-cavity heat-pressure converters may be used after technical and economic evaluation.

13. The cold transfer pipeline’s water supply line must be insulated. Whether the return pipe needs insulation depends on ambient temperature. Cold transfer systems must meet the following requirements:

• (1) Insulation materials should be fire-resistant, moisture-proof, non-toxic, and prevent “cold bridges.” The temperature rise should not exceed 0.6°C per 1000 meters.
• (2) Pipelines can be installed overhead, in trenches, or mounted on walls, but should not be placed in return air lanes.
• (3) Low-temperature refrigerants should use calcium chloride, ethylene glycol, or glycerin solutions, depending on availability, corrosion resistance, solubility, and cost. The solution concentration should be adjusted according to the refrigerant temperature.

14. The cooling system and cooling water network in the mine must be hydraulically balanced. The design should comply with national standards GB 50015 and GB 50019 for building water supply and drainage, as well as heating, ventilation, and air conditioning.

This article is a reprint from online media and represents only the author's viewpoint. It has no connection with the China Labor Insurance Network. If any news articles or comments infringe your legal rights, please contact us, and we will handle it promptly.