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Periodic equivalence ratio modulation method and apparatus for controlling combustion instability

United States Patent

May 9, 2000
View the Complete Patent at the US Patent & Trademark Office
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The periodic equivalence ratio modulation (PERM) method and apparatus significantly reduces and/or eliminates unstable conditions within a combustion chamber. The method involves modulating the equivalence ratio for the combustion device, such that the combustion device periodically operates outside of an identified unstable oscillation region. The equivalence ratio is modulated between preselected reference points, according to the shape of the oscillation region and operating parameters of the system. Preferably, the equivalence ratio is modulated from a first stable condition to a second stable condition, and, alternatively, the equivalence ratio is modulated from a stable condition to an unstable condition. The method is further applicable to multi-nozzle combustor designs, whereby individual nozzles are alternately modulated from stable to unstable conditions. Periodic equivalence ratio modulation (PERM) is accomplished by active control involving periodic, low frequency fuel modulation, whereby low frequency fuel pulses are injected into the main fuel delivery. Importantly, the fuel pulses are injected at a rate so as not to affect the desired time-average equivalence ratio for the combustion device.
Richards; George A. (Morgantown, WV), Janus; Michael C. (Baltimore, MD), Griffith; Richard A. (Morgantown, WV)
The United States of America as represented by the United States (Washington, DC)
09/ 034,613
March 3, 1998
CONTRACTUAL ORIGIN OF THE INVENTION The United States Government has rights in this invention pursuant to the employer-employee relationship of the U.S. Department of Energy and the inventor(s).