US 4,477,245 AGranted

Flame monitoring safety, energy and fuel conservation system

AssigneeThe Babcock & Wilcox Company

InventorsJoseph M. Giachino, Marion A. Keyes, IV

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Abstract

A flame monitor for a burner comprises an oscillator which generates a signal at a characteristic frequency, a flame modulator connected to the oscillator and the burner for modulating the flame which produces an electromagnetic signal at the same frequency and a signal detector for detecting the electromagnetic signal. A bandpass filter is connected to the detector for passing only the signal at the characteristic frequency. Circuitry is provided for detecting the intensity of the electromagnetic signal which is proportional to the flame temperature and which can be used to control the fuel or air supplied to the burner and thus optimize the flame. A single detector can be used to detect the flame from various burners where each burner is supplied with its own characteristic frequency and the detector is multiplexed to share its operation over the various burners. A pressure wave detector is also provided to detect the intensity of a pressure wave in the flame which is divided into the electromagnetic radiation intensity to provide a calibration signal.

Claims8

Dependent claims

A flame monitor for a first burner comprising:

a first oscillator for generating a signal at a characteristic frequency between 60 and 100,000 Hz;
a flame modulator connected to the first burner and to said first oscillator for modulating the flame at the characteristic frequency;
an electromagnetic signal detector associated with the first burner for sensing electromagnetic radiation from the flame;
an electronic bandpass filter connected to the detector for filtering out all but the electromagnetic signal at the characteristic frequency, which electromagnetic signal increases with increased flame temperature wherein said bandpass filter comprises a digital filter, said first oscillator having dual outputs, one for supplying a signal at the characteristic frequency to said flame modulator and the other for supplying a signal equal to 2.sup.n .times.f wherein n is an integer and f equals the characteristic frequency to said digital filter;
a level detector connected to said digital filter for determining the level of the electromagnetic radiation and for providing a stoichiometric combustion control function for said first burner corresponding to that level.

2 more elements

Dependencies are inferred from the claim text.