The United States of America As Represented by the Administrator of the

Richard L Puster

Jag J Singh

William T Davis

John M Franke

Danny R Sprinkle

An acoustic flame-out detection system that renders a large high pressure combustor 12 (FIG. 1) safe in the event of a flame-out and possible explosive reignition. A dynamic pressure transducer 22 is placed in the fuel line 16 and detects the stabilizing fuel pressure oscillations, caused by the combustion process. An electric circuit (FIG. 5) converts the signal from the combustion vortices, and transmitted to the fuel flow, to a series of pulses. A missing pulse detector 39 counts the pulses and continuously resets itself. If three consecutive pulses are missing, the circuit closes the fuel valve 20. With fuel denied, the combustor 12 is shut down or restarted under controlled conditions.

Fuel line based acoustic flame-out detection system

A sensing device 50 comprising an O.sub.2 sensor 22, a pump 37, a compressor 19, and a heater 21 is provided to quickly sense the amount of O.sub.2 in a combustion product gas. A sample of the combustion product gas is compressed to a pressure slightly above one atmosphere by compressor 19. Next, heater 21 heats the sample between 800.degree. C. and 900.degree. C. Next, pump 37 causes the sample to be flushed against electrode 32 located in O.sub.2 sensor 22 6000 to 10,000 times per second. Reference air at approximately one atmosphere is provided to electrode 31 of O.sub.2 sensor 22. Accordingly, O.sub.2 sensor 22 produces a voltage which is proportional to the amount of oxygen in the combustion product gas. This voltage may be used to control the amount of O.sub.2 entering into the combustion chamber 10 which produces the combustion product gas.

Device for quickly sensing the amount of O.sub.2 in a combustion product

A method and device 15 is provided for a quick, accurate and on-line determination of heats of combustion of gaseous hydrocarbons. First, the amount of oxygen in the carrier stream air is sensed by oxygen sensing system 20. Second, three individual volumetric flow rates of oxygen, carrier stream air, and hydrocarbon test gas are introduced into burner 19. The hydrocarbon test gas is fed into burner 19 at a volumetric flow rate n measured by flowmeter 18. Third, the amount of oxygen in the resulting combustion products is sensed by oxygen sensing system 20. Fourth, the volumetric flow rate of oxygen is adjusted until the amount of oxygen in the combustion product equals the amount of oxygen previously sensed in the carrier stream air. This equalizing volumetric flow rate is m and is measured by flowmeter 16. The heat of combustion of the hydrocarbon test gas is then determined from the ratio m/n.

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Hampton, VA, United States of America

Richard L Puster