The Barrick Power Plant in Colorado, also known as the Western 102, is a 115.6MW gas-fired reciprocating plant. It is located next to Sierra Pacific Clark Station substation, 24km east of Reno in Nevada.
Owned by Barrick Goldstrike Mines, the plant is currently serving the company’s mining property in north-eastern Nevada. Its property consists of an open-pit mine, two underground mines and two large milling facilities.
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Barrick is the third genset power plant in the region, the others being the 111MW Plains End plant and the 50MW Red Bluff plant.
Plant construction began in the final quarter of 2004 and was commissioned after a year in 2005.
Plant make-up
The Barrick power plant is built on 15 acres of land with the fenced operational area covering 13 acres.
The plant features 14 20V34SG gensets with a rated capacity of 8.439MW each. Fuelled by natural gas, the gensets are spark ignition machines with pre-combustion chamber technology. The lean fuel gas enables the gensets to operate at low heat and low uncontrolled emission rate.
The plant is also equipped with selective catalytic reduction system, oxidation catalyst and volatile organic compound control. The automatic general control signal allows the plant to be controlled remotely for start, stop and regulation.
The plant building is pre-fabricated with two engine halls that house seven gensets each. It is separated by a section that has a central control room, an MV switchgear area, a motor control centre, and maintenance and personnel facilities area.
The building is equipped with silencers in charge-air piping connected to the engine turbochargers to control noise levels. A large vertical silencer placed in the exhaust gas stack provides additional noise control.
The plant has a redundant buss bar system, set-up transformers and breakers. This arrangement enables it to carry out the operations even in case of transformer failure.
Development
The project engineering and design was carried out by POWER Engineers. Finland-based Wärtsilä assisted in the engine-generator design.
POWER Engineers reviewed the permitting requirement in addition to providing technical support for building and emission permits. The other services provided by the company were site review and selection assistance, transmission line routing identification, major equipment identification, and purchase and administration of survey and geotechnical subcontracts.
Technology
The Wärtsilä 34SG engine is a four-stroke, spark ignited engine that works on Otto Process. It is a medium-speed engine operating at a speed of 720-750rpm at 50-60Hz applications producing 8,700-9,000KW of mechanical power.
The technology is designed for flexible manufacturing methods and long maintenance-free operating periods.
The genset is designed based on the lean-burn principle and is equipped with ported gas admission and a pre-chamber with a spark plug for ignition.
The lean-burn method requires more air in the cylinder to facilitate combustion. With this the peak temperatures are reduced and less nitrous oxide is produced.
A spark plug situated in the pre-chamber initiates the lean-air ignition. Each cylinder is controlled individually to ensure correct air-fuel mixture and the timing of ignition. This control mechanism allows for stable combustion that passes less load on the engine components.
The 34SG engine works without water to meet the heat rate, output and emissions even at high air temperature. The only process where water is used by the engine is for washing the turbochargers and storing small quantities for closed circuit cooling loop water expansion tanks at certain set points. Each genset consumes just 7.5l of water a week.
The Wärtsilä technology provides operating flexibility even when the output drops to 7% of rated output. The spinning reserve reaches the maximum when all the gensets operate together at minimum load. The individual genset heat rate at 50% of the rated output is equal to 90% of the full-load heat rate in comparison with the heat rate of a simple cycle gas turbine.
The engine has the ability to return to full load within ten minutes of shutdown and back to shutdown conditions several times a day. In addition, the technology supplies power to the grid within two-three minutes from the AGC signal when the engine re-starts.
