Session 2: Review of the 500 KW Direct Contact Geothermal Plant at East Mesa
The concept of a binary power cycle utilizing direct contact heat exchangers was first proposed by Jacobs and Boehm in 1973 for use with geothermal brines. This concept was proposed primarily to overcome difficulties associated with the fouling and scaling nature of many moderate temperature brines. However, thermodynamic analyses and subsequent economic analyses clearly pointed to possible economic advantages over conventional binary cycles even with non-fouling, non-scaling brines. For a direct contact binary power plant to be economically attractive it is necessary that a small pinch point be obtainable so that a maximum amount of power can be obtained per unit mass flow of geothermal brine. Since the working fluid comes in direct contact with the brine it must be immiscible with the brine, low in cost and, if part of it goes into solution in the brine, easily recoverable. In addition, noncondensible gases from the brine must be controlled to limit their effect on condenser pressure. The 500 kWe DCHX test facility installed at East Mesa was designed to evaluate techniques to provide economical operation. The choice of the East Mesa test site as a first location to evaluate the DCHX system placed additional requirements on the system. The brine at East Mesa was at low pressure, requiring the use of downhole pumps. The selection of isobutane as a working fluid required increasing the pressure of the brine. The high amount of dissolved CO{sub 2} in the brine required that it be preflashed to prevent the carryover of CO{sub 2} gas through the turbine and into the condenser which would adversely affect the system performance. All of these problems have been met by the system designer and operator, Barber-Nichols Engineering. Further, problems with isobutane turbine design, supposed state-of-the-art, were encountered and resolved.
- Research Organization:
- Barber-Nichols Engr. Co., Arvada, CO 800002 (US)
- Sponsoring Organization:
- U.S. Department of Energy Assistant Secretary, Conservation and Renewable Energy, Division of Geothermal and Hydropower Technologies; Washington, D.C. (US)
- OSTI ID:
- 838142
- Report Number(s):
- CONF-8310177-2; TRN: US200508%%286
- Resource Relation:
- Conference: Proceedings of the Geothermal Program Review II, Washington, DC (US), 10/11/1983--10/13/1983; Other Information: Page range is 58-75; Includes tables, drawings, graphs; PBD: 1 Dec 1983
- Country of Publication:
- United States
- Language:
- English
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