North Brawley Geothermal Power Plant Project

The North Brawley Geothermal Power Plant project consists of five (5) water cooled Ormat Energy Center Units (OEC)*, water system and other auxiliary systems to produce 50 MW of electricity. 

The Plant is an addition to the growing and expanding network of Geothermal Type Power Plants in the area, which make use of the high temperature fluid beneath the surface to produce steam and induce rotation in a turbine / generator configuration.

Construction and Installation of Five (5) 10MW Power Units includes:

• 5 Sets of Heat exchangers such as vaporizers & demisters, preheaters, and condenser & diffusers.
• 5 Power skids (which includes two turbines & a common generator and an oil skid).
• Process piping systems such as geothermal , motive fluid and cooling water.
• Aux. piping systems such as instrument air, motive fluid drainage and seal/lubrication oil.
• Motive fluid purge system
• 5 OEC Power shelters
• Geothermal supply/return piping
• Motive fluid drain and storage system
• Cooling water system
• Compressed air system
• Power distribution and Control systems
• H. V. sub station

The project involves 130,000 MH's of PCL direct labor and consists of approximately $7.5 Million in Civil Work, $9 Million in Mechanical Work, and $4 Million in Electrical work all to be performed in 2008 over the course of 10 months.

**Technical Interest**

The OEC (Ormat Energy Converter) is based on the Rankine power cycle. The cycle uses organic fluid as the working fluid. Working fluid is preheated and evaporated by the heat of the geothermal steam and brine, flowing through the vaporizer and pre-heaters. The working fluid vapors expand through the Turbines, which are coupled to the double shaft ends Generator, producing electrical power.  The exhaust vapors, from the Turbines, flow to water-cooled condensers, where it is condensed.

The motive fluid condensed accumulates at the condenser shell and flows to the feed pumps suction, through liquid filters.

The motor-driven cycle feed pumps; controlled by the vaporizer level control device, pump the working fluid to Pre-heater and then back to the Vaporizer.

The working fluid flows in the shell side of the heat exchangers, while the geothermal fluids flow through the tubes.  Brine from the well's flow through the OEC vaporizer's tubes and then brine utilized to heat the Pre-Heaters. The cold Brine from the OEC is re-injected in dedicated wells.

MAIN COMPONENT OF THE OEC

• Vaporizers
• Pre-Heaters
• Water Cooled Condensers
• Cycle Feed Pumps
• Turbines
• Generator
• Oil skid
• Purge systems
• Piping
• Power and control panels