KBA is Reducing Energy Input on High-Output Presses
Free cooling of temperature control circuit
Another energy-saving option KBA offers is free cooling of the temperature-control circuit. With this system, where the outside temperature is low enough the return circuit is coupled directly to the temperature-control circuit. The level of utilization depends on plant location and the volume of waste heat generated. Test measurements revealed that free cooling was effective for more than 1,000 hours, the equivalent of 11.5 per cent of the annual total.
Assuming 220 working days, each with two shifts, as the operating time for the dual-purpose cooling system, and an average power rating of 6kW for the temperature-control circuit, this represents a total input of 20.9MWh from the cooling circuit. If all other parameters remain unchanged, 1,000 hours of free cooling per year would cut power consumption to 6.45MWh. In the best-case scenario free cooling would be available for 3,000 operating hours, resulting in a potential cost saving of up to €850 per year.
Energy-efficient air supply
An energy-efficient air-compression cabinet should always be water-cooled. By modifying the deployment of different types of compressor energy input for the air supply can be cut by up to 24MWh per year compared to rival cabinets. This is equivalent to a saving of 28 per cent in electricity consumption.
Utilizing waste heat in the return cooling circuit
The waste heat emitted by the press and the water-cooled ancillary devices, and recovered via the return circuit, is potentially a major source of energy, eg for heating purposes. However, it is advisable to consider a number of factors prior to utilizing this energy. If the plant is heated via an economical high-temperature system, there is a problem.
The average temperature in the cooling-circuit feed flow is 40°C. The feed flow of a high-temperature heating system is generally around 70°C to 80°C and the return flow 50°C to 60°C. It is therefore inadvisable to reutilize directly the heat in the return cooling circuit, since it would cool the heating circuit. One way of circumventing this would be to install a heat pump, which would raise the temperature from 40°C to the level required for heating.