Waste Heat Recovery from Air Turbo-Compressors in Mining: A Comparative Study Between Cogeneration and Heat Pump Technologies

Abstract

The possibility of cogeneration and heat pump technologies implementation for waste heat recovery from mining turbo-compressors has been investigated. It has been calculated that heat pump implementation for turbo-compressor heat recovery enables a reduction of compressed air production costs by half. This decrease in costs lessens as cooling water inlet temperature increases. It has been found that instead of burning fossil fuel in coal-burned boilers to meet mines’ needs for thermal energy, it is possible to recover compressor stations’ waste heat by using heat pumps. They can produce 1.6–2.0 MW of useful heat in the form of hot water at a temperature of 50 °C from a single 1.5 MW turbo- compressor, thus reducing the fossil fuel consumption in mines considerably. Cogeneration technology implementation for compressor waste heat recovery has shown that maximum power generation (up to 75 kW) can be achieved, depending on the compressed air temperature leaving the recovery sections of the air coolers (intercooling temperature). It can reduce turbo-compressor energy consumption by up to 5 % and make it possible to save 540 000 kWh of electricity annually from a single 1.5 MW turbo-compressor.