Automatic Main Cooling Water System (aMCWS)

Abstract

The parasitic load in each power generation plant is always predominated by the parasitic load from Main Cooling Water System (MCWS). In conventional power generation (e.g. coal fired, gas, and combined cycle power plants), sea-water is usually applied as the main cooling medium. Variation of sea-water temperature during the year remains relatively constant. This condition differs from conditions at geothermal power plant, where air is the main cooling medium and its conditions (wet bulb temperature and humidity) have wide variation during the year. The idea of this paper is to exploit the changes of air conditions to decrease the parasitic load in Main Cooling Water System. The principle is when the air has low temperature and low humidity, the automatic Main Cooling Water System (aMCWS) will decrease the power consumption of main cooling water pump and/or the cooling tower fan at the optimal conditions. The optimization step of the Main Cooling Water Pump and Cooling Tower Fan is performed by implementing the variable frequency drive (VFD) at the motors so that the rotation of pump and fan can be varied to the actual conditions of air measured. The conclusion of this study clarify that the application of aMCWS can reduce the power consumption of the pump and fan by up to 20% from existing power input. The economic consideration (with investment cost, operating & maintenance cost, and CDM scheme as considered parameters) in this study shows that the application of aMCWS at existing geothermal power plants is feasible.