Benefits of Adopting High Steam Supply Pressure

Abstract

A method is outlined that permits the capital cost implications of alternative steam supply pressures to be quantified, without detailed design and price estimation being necessary. Separate savings or additional costs are evaluated for the steamfield and power plant parts of the project. The method considers the size or rating of a plant item or subsystem and determines the change in size or rating for a change in steam supply pressure. Cost changes are assessed from the estimated cost of the plant item or subsystem using normal rules for the cost of size changes. The method is applied to a comparison of existing and future units at Kamojang geothermal field, West Java, Indonesia. Appreciable cost savings are predicted for 10 bara turbine inlet pressure compared to the existing value of 6.5 bara. These apply to both the steamfield and the power plant developments. In addition, for any given electrical output, the steam withdrawal rate is expected to be about 10% less for the 10 bara case, but the value of this has not been quantified in monetary terms.