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 comfortable working environment for miners.

2. When designing new mines or expanding existing ones, a temperature forecasting method should be used based on geological reports and data provided by the construction company. This helps in planning for future thermal conditions and preventing overheating issues.

3. In cases where temperatures exceed acceptable limits, comprehensive cooling measures must be implemented to maintain a safe and efficient working environment.

4. Natural cooling methods should be utilized based on the mine's specific conditions. This includes using natural air flow, increasing ventilation, directing airflow appropriately, and minimizing heat sources. Measures such as insulating hot areas, managing hot water, and providing personal protective equipment are also essential.

5. Artificial cooling systems should be designed considering the mine’s geology, layout, ventilation system, depth, cooling load, and available water resources. After a thorough technical and economic evaluation, options like mobile air conditioning units, ground-based centralized systems, or combined ground-downhole systems may be selected.

6. Underground air treatment must meet specific requirements:

• (1) Air treatment equipment should be selected based on the system's capacity and cooling load, using direct evaporation, water-cooled surfaces, spray chillers, or spray chambers.
• (2) Air treatment can be centralized or handled at individual cooling sites.
• (3) For large-scale operations or high cooling loads, a comprehensive approach is recommended if single units are not effective or economical.
• (4) The air volume processed by the system should not exceed the supply air volume. At mining faces, it should not exceed 70% of the total air volume available.

7. The condensing heat removal method should be determined based on factors like cooling mode, condensation heat, water quality, temperature, return air conditions, and mining depth. Specific guidelines include:

• (1) Cooling towers or natural water bodies can be used for ground-level heat dissipation.
• (2) Underground water should be prioritized for heat removal when suitable; otherwise, return air or ground discharge may be used.
• (3) If using return air for heat removal, the wet-bulb temperature should not exceed 29°C.

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

9. The cold load backup factor for chillers should range between 110% and 120%. At least two refrigeration units should be installed, and larger systems may require more advanced equipment for high cooling demands.

10. If the refrigeration station is located on the surface, its design and layout must follow national standards like GB 50019. It should be at least 50 meters away from the air intake and positioned under the summer wind direction for optimal performance.

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

12. In deep mines (over 600 meters), a coupling device is required to transfer cold from the ground-based system. The selection of coupling methods should consider safety, energy efficiency, and ease of maintenance. Options like shell-and-tube heat exchangers, water recovery devices, and multi-cavity converters may be used after technical and economic analysis.

13. Cold transfer pipelines must be insulated, especially the supply lines. The return lines should be insulated depending on ambient conditions. Key considerations include fire resistance, moisture protection, and avoiding thermal bridging. The temperature rise should not exceed 0.6°C per 1000 meters of pipe.

14. The cooling and water supply systems must be hydraulically balanced. Design should adhere to national standards like GB 50015 and GB 50019 to ensure efficient and safe operation.

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