Utilization of Chloride Bearing, Superheated Steam

Abstract

Volatile chloride (HCl) is found in geothermal fluids all over the world. When superheated geothermal steam containing HCl cools to saturation temperature, the compound dissolves in the condensate and forms hydrochloric acid. This can have tremendous consequences for equipment as hydrochloric acid aggressively attacks steel and other metals. Severe pitting corrosion can occur and if this happens in the turbine, cracks can form at the bottom of the pits, which will grow larger with fatigue corrosion and lead to a final breakdown. The Icelandic deep drilling project (IDDP) is dealing with extreme circumstances with high enthalpy, superheated geothermal steam containing HCl. Successful corrosion mitigation is essential for the feasibility of the development. There are several possible methods for removing HCl from geothermal steam, including wet scrubbing and dry scrubbing technologies. These scrubbing methods affect the temperature and exergy of the fluid they are applied on, but the resulting efficiency and power output of the plant depends on how the power cycle is configured, and how the cleaning method is incorporated. The goal of this work is to map the applicability of different combinations of scrubbing technologies and power cycles with regard to exergy conservation and cost.