US 5,899,683 AGranted

Process and device for operating a gas burner

AssigneeStiebel Eltron GmbH & Co. KG

InventorsHubert Nolte, Martin Herrs, Roland Merker, Norbert Schwedler, Eckart Bredemeier

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Abstract

In a process for operating a gas blower burner, a control circuit detects an ionization signal Ui derived from an ionization electrode, and it adjusts the gas-to-air ratio to a lambda set point >1, to which a set point Uis of the ionization signal corresponds. To guarantee low-emission combustion in different operating states, a range of control of the ionization signal Ui is set, whose upper limit value Uio is smaller than the maximum of the ionization signal Ui, and whose lower limit value Uiu is above the value that guarantees low-emission operation. A switch-off signal is generated for the burner if the ionization signal Ui leaves the permissible range of control RB for longer than a preset period of time. If the value is lower than the lower limit value Uiu of the ionization signal Ui and when the value is lower than the set point Uis at a lambda value <1, the control circuit increases the gas volume flow to an end value, and another switch-off signal is generated for the burner when this end value is reached.

Claims19

Dependent claims

A process for operating a gas burner, the process comprising the steps of:

providing an ionization electrode in an area of a flame of the gas burner, said ionization electrode generating an ionization signal Ui representing an ionization of the flame;
determining a lambda set point which is greater than one for operation of the gas burner;
determining an ionization set point of said ionization signal corresponding to said lambda set point;
adjusting a lambda of the gas burner to cause said ionization signal to be equal to said ionization set point;
determining a control range for said ionization signal, said control range having an upper limit value Uio which is smaller than a maximum Uim of said ionization signal, and having a lower limit value Uiu which is above an end value Uie of said ionization signal, said end value Uie of said ionization signal corresponding to a lambda value "le" which is less than one and at which combustion of the flame is not low emission;
switching off the gas burner when said ionization signal is outside said control range for longer than a preset period of time;
switching off the gas burner when said ionization signal drops below said lower limit value Uiu of said ionization signal Ui and when said ionization signal drops below said ionization set point Uis at a lambda value <1 as a consequence of positive feedback of said adjusting causing one of gas volume flow to be increased and air volume flow to be throttled to cause said lambda to reach an end value le and said ionization signal to reach end value Uie.

4 more elements

A device for operating a gas burner, the device comprising:

an ionization electrode in an area of a flame of the gas burner, said ionization electrode generating an ionization signal Ui representing an ionization of the flame;
control circuit means for receiving said ionization signal, said control circuit means having a predetermined lambda set point which is greater than 1 for operation of the gas burner and an ionization set point of said ionization signal corresponding to said lambda set point, said control circuit means adjusting a lambda of the gas burner to cause said ionization signal to be equal to said ionization set point, said control means having a predetermined control range for said ionization signal, said control range having an upper limit value Uio which is smaller than a maximum Uim of said ionization signal, and having a lower limit value Uiu which is above an end value Uie of said ionization signal, said end value Uie of said ionization signal corresponding to a lambda value "le" which is less than one and at which combustion of the flame is not low emission, said control circuit means switching off the gas burner when said ionization signal is outside said control range for longer than a preset period of time, said control means switching off the gas burner when said ionization signal equals said end value Uie.

Dependencies are inferred from the claim text.