Rehabilitation of geothermal power plant. ; Focusing on Tongonan power plant. Chinetsu hatsudensho no rehabilitaion. ; Tontonan hatsudensho wo shoten ni shite

A description based on the experiences given by Tongonan power plant in the Philippines is given on the problems and the improvement relating to the operation and repair of geothermal power plants. As causes for the shutdown of Tongonan power plant, turbine scaling occupies their 75% and the percentage lowers in the order of transmission lines and corrosion due to H2S gas. Scale attachment brought about the decrease of steam inflow to the turbine and blade breakage caused by the contact between the scale and rotor. For preventing scaling and removing scale, preventive and corrective measures have been examined. The initial effective height of flue gas exhaust was low and the concentration of landing H2S gas in the yard of the power plant was high and reached a maximum value of 2.6ppm. The effect of the improving construction on gas diffusion was significant. While steam condensate has been used as plant coolant, the situation that the chemical for adjusting the quality of water became out of stock occurred, resulting in a marked corrosion of carbon steel pipes. As measures against these, the chemical injection system was automated and the cooling pipes were replaced for stainless or FRP pipes. 3 refs., 6 figs., 3 tabs.