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Title: Comparative analysis of alternative means for removing noncondensable gases from flashed-steam geothermal power plants

Technical Report ·
DOI:https://doi.org/10.2172/758765· OSTI ID:758765

This is a final report on a screening study to compare six methods of removing noncondensable gases from direct-use geothermal steam power plants. This report defines the study methodologies and compares the performance and economics of selected gas-removal systems. Recommendations are presented for follow-up investigations and implementation of some of the technologies discussed. The specific gas-removal methods include five vacuum system configurations using the conventional approach of evacuating gas/vapor mixtures from the power plant condenser system and a system for physical separation of steam and gases upstream of the power turbine. The study focused on flashed-steam applications, but the results apply equally well to flashed-steam and dry-steam geothermal power plant configurations. Two gas-removal options appear to offer profitable economic potential. The hybrid vacuum system configurations and the reboiler process yield positive net present value results over wide-ranging gas concentrations. The hybrid options look favorable for both low-temperature and high-temperature resource applications. The reboiler looks profitable for low-temperature resource applications for gas levels above about 20,000 parts per million by volume. A vacuum system configuration using a three-stage turbocompressor battery may be profitable for low-temperature resources, but results show that the hybrid system is more profitable. The biphase eductor alternative cannot be recommended for commercialization at this time.

Research Organization:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Organization:
US Department of Energy (US)
DOE Contract Number:
AC36-99GO10337
OSTI ID:
758765
Report Number(s):
NREL/SR-550-28329; TRN: AH200025%%3
Resource Relation:
Other Information: PBD: 20 Jun 2000
Country of Publication:
United States
Language:
English