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Gas Turbine Combustor Loss of Flame Detection

Introduction

The LM engine is monitored and protected for loss of flame during operation. This position paper provides the loss of flame protection systems that are used on GE Energy Aero LM gas turbine engines. Description

Standard offering LM gas turbine control systems have built in loss of flame detection, which is achieved by using special algorithms that compare engine speed, fuel flow and compressor discharge temperature -T3. This flameout detection algorithm, N25DOT, would initiate shutdown to the gas turbine within 0.600 seconds to protect the machine. For EU and Australia based applications that require additional SIL protection, GE Energy Aero standard offering provides UV flame detector sensors that fit on the engine case to detect combustion flame. The UV flame detector sensor comply with the following standards:

• ETL and ETL Canada listed for Class I, Division 2, Group A, B, C and D, normally non-arcing components. Control number 9900287.

• Conforms to UL standard 1604

• Certified to CAN/CSA standard C22.2 No. 213

• DEMKO listed Ex n V IIC T3 and Ex N IIC T3, normally non-arcing components. Control number 98Y.125086X

• GE Aircraft Engine – Specification M50TF1828 CL-B

• FAA – Federal Aviation Agency

• CE Mark: EN 61000-4-1 - EMC basic immunity test EN 61000-4-4 - EMC transient/burst immunity EN 50140 - EMC radiated immunity EN 50141 – EMC conducted immunity

Other safety features include:

• UV flame sensor is classified as normally non-arcing

• Operating temperature range of the flame sensor is –300C to 1250C

• Heat soak temperature rating 2050C, 4 hours

• Response time < 25milliseconds

GE Energy Aero Energy Division

Position Paper #60

Rev A

December 1, 2009

16415 Jacintoport Blvd

Houston, TX 77015

USA T 001-281-864-2803

F 001-281-864-2977

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• Power requirements is 12 – 30 VDC @ 100 ma The critical safety flame out time of the LM6000 PD is 3.57 seconds, where explosive LEL would be achieved. The flame sensor system total time response to detect loss of flame is 0.325 seconds. Therefore, the UV flame detector system meets protection requirements per AS 3814. - UV flame detector = 0.025 seconds - SIS system dwell time (typical) = 0.300 seconds - Gas fuel block valve response time to close = 1.0 seconds TOTAL TIME = 1.325 seconds The UV flame sensor is solid-state optical sensor designed to ATEX Directive to prevent arcing failure mode. The sensor has been demonstrated with 8gs continuous and 12g extreme vibration testing which proved the current design reliability. Sensor has operating output signal band of 4-20mA dc, which provides a continuous self-check capability where as a “no signal” (failed sensor) would indicate sensor failure. Failed sensor deadband range shall be configured for < 3.80 ma or > 21.2 ma. GE’s installation of the flame safeguard system includes redundant sensor for reliability enhancement. It is recommended that 1oo2 voting for loss of flame detection or failed sensor during lightoff and operation provides alarm only. It is recommended that 2oo2 voting for loss of flame detection or failed sensor during operation provides shutdown. It is recommended that a dwell time of 0.300 seconds be incorporated in control system for loss of flame detection to combat sensor flickering response. In consideration to Australian codes, AS 3814 clause 2.24.1 states, “A flame safeguard system shall incorporate a certified flame safeguard that complies with-

(b) AS 4620 for thermoelectric types; (c) AS 4625 for electronic types; or; (d) An approved equivalent standard. (e) Trips the GT within the flameout event safety critical time

It is GE’s position that the proposed installation of UV flame sensor would provide an equivalent level of safety as prescribed by AS 3814 clause 2.24.1. The current deployed UV flame sensor, part number FS-RS-9001, is the only device recommended by OEM manufacture - GE Energy Aero that is approved and qualified for LM gas turbine applications.

Conclusion

LM gas turbine loss of flame protection is a very important safety function in GE’s control system. Adequate protection from loss of flame is provided in the GE control system via software algorithm logic, as standard offering. Optional loss of flame protection can also be provided via UV flame protection hardware kit for combustion flame detection.

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