A gas burner system has a gas burner with a conduit through which an air-gas mixture is conducted; a variable-speed forced-air device that forces air through the conduit; a control valve that controls a supply of gas for mixture with the air to thereby form the air-gas mixture; and an electrode configured to ignite the air-gas mixture so as to produce a flame. The electrode is further configured to measure a flame ionization current associated with the flame. A controller is configured to actively control the variable-speed forced-air device based on the flame ionization current measured by the electrode so as to automatically avoid a flame harmonic mode of the gas burner. Corresponding methods are provided.

Control unit for detecting a flame in operation using flame monitors suitable for burners operated using a fuel, wherein the flame monitor comprises at least one sensor as operating means for detecting the radiation emission from a flame as a visible reaction between fuel and oxidizing oxygen in a combustion region, and an evaluation circuit associated with the at least one sensor, the evaluation circuit determining whether the radiation received by the sensor corresponds to that of a burning flame and, if the result is negative, generating a fuel supply switch-off signal, wherein at least two flame detectors are connected in such a way that a basic electrical circuit is formed which processes the output signals of the at least two flame monitors via closing contacts in an OR operation or via closing contacts in an AND operation, depending on which of at least two operating states of flame detection is assigned to the output signals of the flame monitors, and a switching logic is provided for switching between the at least two operating states, which logic links an intelligent subsystem with a logic function plan.

A combustion apparatus includes a burner configured to produce flames, a first flame rod and a second flame rod, and a controller. The burner is configured to be controlled, by the controller, to be in a first output state, and a second output state in which output is smaller than in the first output state. The first flame rod makes contact with the flames produced at the burner in a normal combustion state. The second flame rod makes contact with the flames produced at the burner in the normal combustion state when the burner is being controlled to be in the first output state, and does not make contact with the flames produced at the burner in the normal combustion state when the burner is being controlled to be in the second output state.

Various embodiments include a control system comprising: an ionization electrode; a flame sensor; a first signal conditioning circuit for the ionization electrode; a second signal conditioning circuit for the flame sensor; an output unit; and a processor. The processor: receives a first and a second ionization signal indicative of ionization currents from the first signal conditioning circuit; receives a first and a second flame signal indicative of radiations originating from a flame via the second signal conditioning circuit; produces a derived ionization signal as a function of the first and the second ionization signals; produces a derived flame signal as a function of the first and the second flame signals; determines if a flame lift-off condition exists based on the derived ionization signal and the derived flame signal; and if a flame lift-off condition exists, produces a safety signal and transmits the safety signal to the output unit.

A gas burner system has a gas burner with a conduit through which an air-gas mixture is conducted; a variable-speed forced-air device that forces air through the conduit; a control valve that controls a supply of gas for mixture with the air to thereby form the air-gas mixture; and an electrode configured to ignite the air-gas mixture so as to produce a flame. The electrode is further configured to measure a flame ionization current associated with the flame. A controller is configured to actively control the variable-speed forced-air device based on the flame ionization current measured by the electrode so as to automatically avoid a flame harmonic mode of the gas burner. Corresponding methods are provided.

Various embodiments include a control system comprising: an ionization electrode; a flame sensor; a first signal conditioning circuit for the ionization electrode; a second signal conditioning circuit for the flame sensor; an output unit; and a processor. The processor: receives a first and a second ionization signal indicative of ionization currents from the first signal conditioning circuit; receives a first and a second flame signal indicative of radiations originating from a flame via the second signal conditioning circuit; produces a derived ionization signal as a function of the first and the second ionization signals; produces a derived flame signal as a function of the first and the second flame signals; determines if a flame lift-off condition exists based on the derived ionization signal and the derived flame signal; and if a flame lift-off condition exists, produces a safety signal and transmits the safety signal to the output unit.

A combustion apparatus includes a burner configured to produce flames, a first flame rod and a second flame rod, and a controller. The burner is configured to be controlled, by the controller, to be in a first output state, and a second output state in which output is smaller than in the first output state. The first flame rod makes contact with the flames produced at the burner in a normal combustion state. The second flame rod makes contact with the flames produced at the burner in the normal combustion state when the burner is being controlled to be in the first output state, and does not make contact with the flames produced at the burner in the normal combustion state when the burner is being controlled to be in the second output state.

A flame sensor apparatus includes a sensor assembly. The sensor assembly includes a photodiode for sensing characteristics of a flame. The photodiode outputs an electrical photocurrent. The sensor assembly includes an electrical assembly that is electrically remote from the sensor assembly. The sensor assembly includes an electric cable assembly extending from the sensor assembly to the electrical assembly. The electric cable assembly includes an electrical cable to electrically convey the photocurrent to the electrical assembly. At least the sensor assembly is configured and constructed to experience and continue to operate at a temperature at or greater than 200 C.

The present invention concerns a flame detector with optical sensors situated within a housing, which is coupled to a signal collector and focuser enclosure. The enclosure includes a reflective surface or reflective surfaces generally oriented outwardly and in optical communication with the sensors through a shield window exposing the sensors; the shield window is situated between the enclosure and the housing of the flame detector. The enclosure may have a conical shape, a parabolic shape, and may include convex or concave surfaces that reflect emission signals from an emission signal source to the sensors in optical communication with the reflective surfaces. The enclosure is thus adapted to collect emission signals and narrow or focus a field of view of the sensors, thereby increasing a detection range between the flame detector and an emission signal source such as a flame source.

A gas burner system has a gas burner with a conduit through which an air-gas mixture is conducted; a variable-speed forced-air device that forces air through the conduit; a control valve that controls a supply of gas for mixture with the air to thereby form the air-gas mixture; and an electrode configured to ignite the air-gas mixture so as to produce a flame. The electrode is further configured to measure a flame ionization current associated with the flame. A controller is configured to actively control the variable-speed forced-air device based on the flame ionization current measured by the electrode so as to automatically avoid a flame harmonic mode of the gas burner. Corresponding methods are provided.