Burner flame sensing system and method

Claim 2

A flame analyzer comprising: a sensor for detecting radiation produced by a flame and producing an electrical signal indicative of the radiation; means for converting the electrical signal into a spectrum comprising a plurality of component frequencies of the electrical signal, the component frequencies resulting from changes in power of the flame with time, and wherein each component frequency has an amplitude; means for determining a degree of linearity of a distribution of component frequency amplitudes throughout the spectrum; and means for determining a characteristic of the flame in response to the degree of linearity.

Claim 3

The flame analyzer as recited in claim 1 wherein said means for converting the electrical signal comprises means for performing a Fourier transformation on the electrical signal.

Claim 4

The flame analyzer as recited in claim 1 wherein said means for determining a degree of linearity comprises means for determining a difference between slopes of the distribution of component frequency amplitudes at at least two frequencies of the spectrum.

Claim 5

The flame analyzer as recited in claim 1 wherein said means for determining a degree of linearity comprises means for determining a linearity regression correlation (R) for the distribution of component frequency amplitudes as given by the expression: ##EQU4## where n is the number of component frequencies and s i is the amplitude of a component frequency f i .

Claim 6

The flame analyzer as recited in claim 1 wherein said means for determining a degree of linearity comprises: means for deriving data values for a set of the component frequencies, each data value being defined by an equation of a line tangent at a given point to the distribution of component frequency amplitudes; and means for integrating the difference between the amplitude produced by said means for converting and the data value for each member of the set of component frequencies to produce a first value indicative of the degree linearity.

Claim 7

The flame analyzer as recited in claim 5 wherein said means for determining a degree of linearity further comprises: means for determining a difference between slopes of the distribution of component frequency amplitudes at two locations, wherein the difference is a second value indicative of the linearity of the spectrum; and means for determining a linearity regression correlation for the distribution of component frequency amplitudes wherein the linearity regression correlation is a third value indicative of the linearity of the spectrum.

Claim 8

The flame analyzer as recited in claim 6 wherein said means for determining a characteristic of the flame comprises: a first means for comparing a plurality of the first values to a first threshold to determine amounts of the first values that are respectively above and below the first threshold; a second means for comparing a plurality of the second values to a second threshold to determine amounts that are respectively above and below the second threshold; a third means for comparing a plurality of the third values to a third threshold to determine amounts that are respectively above and below the third threshold; first means for averaging the amounts of the first, second and third values below their respective thresholds to produce a first average; second means for averaging the amounts of the first, second and third values above their respective thresholds to produce a second average; and means for producing an indication that the flame is extinguished when the first average exceeds a first reference value, and for producing and indication that the flame is present when the second average exceeds a second reference value.

Claim 11

The flame analyzer as recited in claim 8 wherein said means for determining a degree of linearity determines a difference between slopes at two locations along the distribution of the logarithmic values.

Claim 12

The flame analyzer as recited in claim 8 wherein said means for determining a degree of linearity determines a linearity regression correlation for the distribution of the logarithmic values.

Claim 13

The flame analyzer as recited in claim 8 wherein said means for determining a degree of linearity comprises: means for defining a line tangent to a given point along the distribution of logarithmic values; and means for integrating a series of differences between the logarithmic values and points on the defined line thereby producing a first value indicative of the linearity of the logarithmic values.

Claim 14

The flame analyzer as recited in claim 11 wherein said means for determining a degree of linearity further comprises: means for determining a difference between slopes at two locations on the distribution of logarithmic values to produce a second value indicative of the degree linearity; and means for determining a linearity regression correlation for the distribution of logarithmic values to produce a third value indicative of the degree of linearity.

Claim 15

The flame analyzer as recited in claim 12 wherein means for evaluating the degree of linearity comprises: a first means for comparing a plurality of the first values to a first threshold to determine an amount of the first values below the first threshold and an amount of the first values above the first threshold; a second means for comparing a plurality of the second values to a second threshold to determine an amount of the second values below the second threshold and an amount of the second values above the second threshold; a third means for comparing a plurality of the third values to a third threshold to determine an amount of the third values below the third threshold and an amount of the third values above the third threshold; first means for averaging the amounts of the first, second and third values below their respective thresholds to produce a first average; second means for averaging the amounts of the first, second and third values above their respective thresholds to produce a second average; and means for producing an indication that the flame is extinguished when the first average exceeds a first reference value, and for producing and indication that the flame is present when the second average exceeds a second reference value.

Claim 18

The method as recited in claim 14 wherein said step of transforming the electrical signal comprises performing a Fourier transformation of the electrical signal.

Claim 19

The method as recited in claim 14 wherein said step of determining a degree of linearity comprises deriving a logarithmic value for each amplitude value; and determining a degree of linearity of a distribution of the logarithmic values.

Claim 20

The method as recited in claim 14 wherein said step of determining a degree of linearity comprises deriving a difference between slopes at two points on the distribution of the amplitude values.

Claim 21

The method as recited in claim 14 wherein said step of determining a degree of linearity comprises means for determining a linearity regression correlation for the distribution of the amplitude values.

Claim 22

The method as recited in claim 14 wherein said step of determining a degree of linearity comprises: deriving data values for the component frequencies from an equation of a line tangent at a given point to the distribution of the amplitude values; and integrating the differences between an amplitude value and a data value for each component frequency in a given frequency band to produce a first value indicative of the degree of linearity.

Claim 23

The method as recited in claim 19 wherein said step of determining a degree of linearily further comprises: determining a difference between slopes at two points on the distribution of amplitude values to produce a second value indicative of the degree of linearity; and determining a linearity regression correlation for the distribution of the amplitude values to produce a third value indicative of the degree of linearity.

Claim 24

The method as recited in claim 14 wherein said step of determining a degree of linearity comprises: comparing a plurality of the first values to a first threshold to determine an amount of the first values that are below the first threshold and an amount of the first values that are above the first threshold; comparing a plurality of the second values to a second threshold to determine an amount of the second values that are below the second threshold and an amount of the second values that are above the second threshold; comparing a plurality of the third values to a third threshold to determine an amount of the third values that are below the third threshold and an amount of the third values that are above the third threshold; averaging the amounts of the first, second and third values that are below their respective thresholds to produce a first average; averaging the amounts of the first, second and third values that are above their respective thresholds to produce a second average; and wherein said step of employing the degree of linearity to determine a flame characteristic produces an indication that the flame is extinguished when the first average exceeds a first reference value, and produces and indication that the flame is present when the second average exceeds a second reference value.