Pressure feedback signal to optimise combustion air control

A combustion control system for two or more burners with a common air supply, comprising;

• a) a means for controlling air flow;
• b) a means for controlling fuel flow substantially in proportion to said air flow;
• c) a pressure transducer for sensing air pressure downstream of said means for controlling air flow and producing a pressure signal indicative thereof;
• d) an electronic pressure controller for controlling said means for controlling air flow in response to inputs from the pressure signal and a pressure set-point value;
• e) a temperature transducer for sensing process temperature and producing a temperature signal indicative thereof;
• f) an electronic temperature controller for generating a temperature controller output signal in response to input from the temperature signal and a temperature set-point value;
• g) a means for connecting the temperature controller with the pressure controller such that the temperature controller output signal is used as the pressure set-point value;
• whereby the air pressure is controlled in proportion to said temperature controller output signal such that when any number of the burners is shut off, said air flow is automatically adjusted so that air flow to the burners remaining on is kept substantially constant.