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Temperature and Burner Control in single 3504

A Temperature Control Loop driving an Air/Gas Ratio Burner Loop in a single instrument.

On behalf of the glass industry (but not restricted to) effort has been made to transfer a temperature control loop driving a gas/air burner combustion pair into a single Eurotherm 3504 controller.

Recommended is the use of single module isolated analogue inputs and outputs. In case other IO is required (eg. Valve Positioning) the control strategy can be modified accordingly.

Simplified cross limited combustion control is achieved.
Control loops maintain their control mode.

Security is in place for:
If a failure in the IO circuitry is detected the control will shut down to safe situation.
Only engineers are able to take either air or gas control in manual.

In ordinary applications the output of the temperature loop forms the heat/energy demand being the amount of gas required.
Assuming the gas loop is the slowest this demand can go “directly” to the output and the air loop being the fastest loop should take care of sufficient surplus air for combustion.
To achieve this, the air loop operates in remote following the highest of the demand or gasflow times ratio setpoint.
The gas output follows the lowest of the demand, actual air setpoint or air flow divided by the ratio setpoint.

Pdf and strategy file available on request.
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