Specifications subject to change without notice. Copyright © 2010 MISTRAS Group, Inc. All Rights Reserved. www.mistrasgroup.com
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PHYSICALACOUSTICSLIMITED
#410A-11100-01
HealtH & Safety executive (HSe) iSSueS ReviSeD GuiDaNce ON GaS tuR-BiNe SafetyHSE has launched a revised edition of its suc-cessful Guidance Note ‘Control of safety risks at gas turbines used for power generation’ (*Guidance Note PM 84).
“Once a gas turbine is in service, a regular scheme of inspection for leaks should be de-veloped and implemented”.
“All potential options for carrying out the work from outside the (acoustic) enclosure should be considered first before allowing entry. In-strumentation with remote indication should be used to avoid routine entry”.
tecHNOlOGy fOR Safety PeRfORmaNce aND OPtimiSatiON Of GaS tuRBiNeSThe Combined Cycle Gas Turbine (CCGT_ Acoustic Leak Detection System monitors criti-cal areas of the turbine for gas/air leaks and provides instantaneous feedback to the on-site distributed control system (DCS). In the event of a high pressure gas/air leak, an air-borne ultrasonic signal will be generated. This signal is detectable by sensors located around the inside of the acoustic enclosure.
The sensors are tuned to listen for high pres-sure leaks and have a significantly reduced sensitivity to the normal background noise produced by the turbine. The signal from each sensor is processed by a small unit adjacent to the sensor which has an industrial standard 4-20ma power/signal output to its safety bar-rier housed outside the enclosure. From here the signals go to the plant DCS and the high frequency acoustic noise levels (dBAE) are cal-culated, displayed over time, and correlated with plant conditions.
An alarm may be generated for any abnormal condition. Approximate source location can be obtained from the relative ultrasonic signals.
combined cycle Gas turbine leak Detection
Product Application
ccGt leak Detection Benefits • Simple to install and operate.
• Instantaneous detection of both gas and air leaks.
• Technology offers approximate source location.
• Certified as intrinsically safe: ATEX II 1 G D and EEx ia IIC T4.
• 4-20ma outputs to plant distributed control system.
• Prevents serious damage to gas tur-bine: Detection of air leaks at an early stage in development.
• Conformity to HSE guidance note PM 84: Reducing requirement for entry into turbine enclosure.
• Supplements conventional exit air sam-pling systems
Sensor locations within Acoustic Enclosure
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