Pipe material selection for 50MWE geothermal power plant pipelines

Abstract

Paper presented at the 7th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Turkey, 19-21 July, 2010.

Piping materials for geothermal systems have been of numerous types with great variation in cost and durability. The temperature and chemical quality of the geothermal fluids, in addition to cost, usually determine the type of piping network material used. In this paper, four suitable types of piping materials according to chemical quality and temperature of the fluid were taken into consideration for Meshkinshahr 50MWe geothermal power plant pipelines. Pipelines consist of two lines that transport the mixture of brine and steam from wellhead to separators, two steam lines from separator to power house and two brine lines from separator to reinjection wellheads. The design parameters; number of expansion loops and legs, pressure drop, wall thickness, weight span. pipe weight and length of the pipe are variable with different pipe materials. Each parameter has a specific significance in each line. For example, in steam lines, pressure drop is more important than that in other lines and less pressure drop in steam lines lead to increase the inlet pressure of turbine and more output power. Also, these parameters directly affect the cost of piping, fewer expansion loops and legs lead to use less pipe length and less pressure drop, larger weight spans result in less pipe supporting costs, and different thicknesses make different pipe unit weight and different transportation costs. In this paper we tried to select pipe material for a 50 MWe geothermal power plant pipelines.