Zero Solids Condensate Corrosion in Steam Pipes at Wairakei

Abstract

Wairakei, the world's first water dominated geothermal power plant station, has been in continuous service for over 22 years. During this period the production field output has declined steadily. The field rundown has been countered in various ways, principally by the introduction of double and triple flashing and by the gradual reduction in wellhead pressure on the high pressure (HP) wells so as to maintain fluid flow, coupled with selective derating of bores to the next lower operating pressure. However, these remedies appear to have caused corrosion in the HP steam liens to the extent of seriously threatening their pressure integrity. Extensive experimentation and studies were carried out before a cure was obtained. This report details the work carried out by the Electricity Division and the Department of Scientific and Industrial Research (DSIR) on this problem.