Advantages of pneumatic gas burners

Air/gas ratio control in industrial heating equipment is of great importance for costefficient and safe operation. If the excess air is too high, gas consumption increases while an air deficiency represents a source of danger.

Pneumatic ratio control is implemented with air/gas ratio controls in accordance with EN 12067-1, whereby combination controls, which also act as shut-off valves, are used frequently. Depending on the design of the control, one can distinguish between air/gas ratio controls and variable air/gas ratio controls. Air/gas ratio controls record the static air pressure as a reference variable and regulate the static gas pressure to the same value. Flow adjustment is carried out via manual adjustment elements so that the air/gas ratio on the burner corresponds to the desired value at the same gas and air supply pressure.

Fluctuations in the air or gas supply pressure as well as in the backpressure in the combustion chamber do not have an effect on the air/gas ratio since the change in the air and gas flow rates is of the same ratio (same change in the pressure gradient for air and gas). Variable air/gas ratio controls work with differential pressure measurements instead of static pressure measurements. The advantage of these controls is that the signals are always proportional to a flow rate and the static pressure must not be considered.

The control process is therefore not influenced by the combustion chamber pressure or by damage to/dirt on the burner. Moreover, the variable air/gas ratio control can be used for hot air if the differential air pressure is measured on the “cold side”. The pneumatic air/gas ratio controls present a flexible solution which can be used for modulating and impulse control. Commissioning of burner systems with pneumatic air/gas ratio controls is simple and is confined to adjusting the air and gas flow rates at low-fire rate on the controller and at maximum capacity using manual adjustment elements on the burner. The opening characteristic of the control elements has no influence on ratio control.

Hundreds of thousands of devices which are being used in industrial applications worldwide demonstrate their operational safety and reliability.