Operational and Field Test Results from the 500 kW Direct Contact Pilot Plant at East Mesa

Abstract

A 500 kw geothermal power plant utilization direct contact hear exchange (DCHX) between geothermal brine and an isobutane working fluid is currently operating at the East Mesa test facility. The pilot plant program was initiated to determine the feasibility of large scale direct contact heat exchange and associated plant operations. In addition to verifying the design performance of the DCHX itself, test efforts to date have 1) quantified the effect of dissolved gases (primarily CO2) transferred from the brine to the IC4 loop on the pressure elevation in the unvented power condenser and demonstrated a viable scheme to control this pressure elevation, 2) evaluated the potential of flash extraction and recovery of dissolved IC4 from the spent brine, and 3) demonstrated control of fouling in critical components by pretreating the brine with small amounts of a chemical additive (FLOCON 247, Pfizer, Inc.)