Compressed Air Best Practices - February 2009 - (Page 23)

Focus Industry POWER PLANTS | 02/09 | Instrument Air for Measurement and Safety To produce electricity in the most efficient manner, the flow of steam and condensate, as well as levels in the heat exchangers must be monitored and controlled. Many of the instruments that monitor flow, level, pressures and temperatures incorporate instrument air quality compressed air (instrument air) to transfer information. Flow and level control is accomplished by the throttling operation of air-operated valves (AOVs). The AOVs require instrument air (clean, dry compressed air). Normally, the resulting load on the Instrument Air System is relatively constant. The high-quality air prevents the small ports on instruments, controls and AOVs from becoming clogged with debris, moisture or oil, which could prevent the proper operation of the equipment supporting the efficient production of electricity. As noted, nuclear energy is produced by the fission of Uranium235. The fission process, as well as fission products resulting from the fission, produces radiation. The safe and proper operation of a Nuclear Power Plant ensures the nuclear fuel and fission products will be contained in an acceptable configuration so as to not cause harm to plant operators or the general public. At some nuclear power plants, instrument air is required to assist in safely shutting down a nuclear power plant in the event of an emergency ensuring that the barriers to the release of radioactive contamination will be maintained. Yet, in most nuclear power plants, instrument air is not required to perform these functions as all the components required to perform these functions either do not use compressed air or the air controlled components fail in the position required to prevent release of radioactive contaminants (3). As at all industrial facilities, compressed air is also used for supplement uses such as operating air driven tools and pumps. This is commonly designated as service air and is separate from the Instrument Air System. The Service Air System may be used as backup for instrument air. CO2 O CANUG The Compressed Air Nuclear Users Group (CANUG) was formed in 1988 with the objective being to exchange information between Compressed Air Systems Engineers serving nuclear power plants. Eighty members share the need to improve the reliability, availability and reduction in cost of the compressed air systems that serve the valves, instruments and other components utilizing compressed air in controlling the conversion of nuclear energy to electricity. Instrument Air at the Oconee Nuclear Station Oconee Nuclear Station’s (ONS, three unit station) original Instrument Air System configuration incorporated three Worthington Reciprocating Compressors (HBB 14x13, 489 cfm each) supported by refrigerant dryers. During initial startup and operation, Oconee’s Instrument Air system normally operated with two compressors in run, one in standby, supporting the operation of the air-operated valves and instruments of Units 1 and 2 as well as tooling and sewage ejectors. ONS realized more compressed air capacity was required. In the mid 1970s, a separate Service Air System was installed, using two oil-flooded Sullair Rotary Screw compressors (150 Series), to support tooling and sewage ejectors. www.aovusersgroup.com/canug.html kW www.airbestpractices.com 23 http://www.aovusersgroup.com/canug.html http://www.airbestpractices.com

Table of Contents Feed for the Digital Edition of Compressed Air Best Practices - February 2009

Compressed Air Best Practices - February 2009 Contents From the Editor Utility-Air News Compressed Air Audit of the Month Air Standards Instrument Air in Nuclear Power Plants Seven Sustainability Projects for Industrial Energy Savings The Pneumatic Advantage Personal Productivity Resources for Energy Engineers Wall Street Watch Advertiser Index Classifieds

Compressed Air Best Practices - February 2009

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