This paper reports how evolutionary advances in pump design and materials selection have resolved most of the early problems, producing third- generation pumps which have run as long as 20,000 hours. Early experience revealed many problems with downwell pumps, resulting in a mean-time-to-failure (MTTF) in 1981 of less than 1000 hours for the best more » available technology. Initially there were many technological obstacles to exploitation of these resources, with one of the greatest being the absence of reliable high-capacity downwell brine production pumps to supply the required amounts of brine from an economically small group of wells. = C) are prime candidates for binary-cycle power generation in the United States and abroad, and constitute about 80% of the known power-capable resources in the United States. The survey found almost no development of high-temperature geothermal electric submersible pumps (ESP's) or close-coupled downwell hydraulic turbopumps, and concluded that considerable development and demonstration will be needed before these technologies are able to compete with existing high-temperature geothermal lineshaft pump technology. Based on recent advances more » which appear likely to eliminate most premature failures, the estimated near-term MTTF will be on the order of 8000 h. In the recent past, pump lives in excess of 7000 h have become common, but a high continuing rate of premature failures resulted in a mean time-to-failure (MTTF) of about 5000 h. Case histories of 72 lineshaft pumps installed at three geothermal binary plants since late 1981 are documented, including some detailed cause of failure reports. This survey traces the development of lineshaft pump technology from the late 1970s to the present (mid-1987), detailing the advances in design, materials selection, and operating practices. This survey of high-temperature geothermal downwell pump users and manufacturers updates a prior survey (AP-3572) completed in early 1983. However, steady progress has been made since 1981, and a large body of experience has been acquired by three geothermal binary plants. The successful exploitation of these resources requires reliable high-capacity downwell brine production pumps, but earlier experience showed that high-capacity, high-temperature geothermal production pumps had many problems which resulted in a mean time-to-failure (MTTF) of less than 1000 h. Geothermal resources with temperatures between 250/sup 0/ and 360/sup 0/F (121/sup 0/C and 182/sup 0/C) are prime candidates for binary-cycle power generation, and constitute about 80% of the power-capable resources in the United States.
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