Condenser And Hybrid Gas Removal System Design For A High Non-Condensible Load Plant
ABSTRACT
The amount of non-condensible gas contained in a geothermal resource affects the design considerations for an efficient and cost effective power plant. This discussion will be centered on the design considerations for the condenser and hybrid ejector/compressor gas removal system for the Central California Power Agency No. 1. (CCPA No. 1) Coldwater Creek Geothermal Power Plant. The plant design utilizes two 65 MW steam turbine generators with a net output of 116 MW. Plant non-condensible loads are estimated in the range of 1.7-2.2% of total flow.
Each turbine has a 166,000 sq. ft. condenser and each condenser is serviced by three 50% capacity non-condensible gas removal systems. Two of the systems are hybrid steam ejector/centrifugal compressor systems. The third system, for standby use, is a three stage steam ejector.
INTRODUCTION
In preparation for the procurement of equipment for the Coldwater Creek Power Plant, CCPA No. 1, through its engineers, Stone and Webster Engineering, undertook the investigation of alternate technology applications for non-condensible gas removal from steam condensers. After an extensive investigation carried out over several months it was determined that alternate technologies to conventional steam ejectors could be utilized in a cost effective manner. Specifications were prepared which allowed contractors the option of assessing and offering various combinations of technologies.
In the fall of 1984 contractors were invited by CCPA No. 1 to submit economically competitive proposals for furnishing and erecting the main condenser and supply of the gas removal system for the Coldwater Creek Geothermal Plant. The plant consists of three floors and the physical space allocated by CCPA No. 1 for the gas removal equipment is limited to a single bay within the plant 25’0” wide by 300'0" in length. CCPA No. 1 stipulated that any rotary equipment which might be proposed must be placed on the first floor with allowance made for future additional equipment should the plant experience an increase in the non-condensible load at some future date.