Domestic Burner Control Fuel Burners, Gas Condensing Boilers

1 Domestic Burner Control (Fuel Burners, Gas Condensing Boilers) 

An oil burner or gas condensing boiler which does not operate at its optimum setting will not only decrease in efficiency, but the concentration of CO, HC and the content of soot in the exhaust gas will also increase. A measure for the quality of combustion is the well-known (in the automotive industry) lambda- (2-) value (see also chapter 53.2.4). 

A 2-value smaller than 1 means that there is an excess of fuel in the mixture. In this case the air/fuel mixture is called rich. If more air is in the mixture than needed for a complete fuel combustion (2 1) the term lean mixture is used. Ideally the combustion is complete at 2 = 1. Real fuel cannot be combusted without an increase in CO and soot at 2-values smaller than 1.05. Due to changing operation conditions, for example a soiled burner, wear of the nozzle or leaky flaps, change of gas quality or changes of temperature and air pressure in the ambient atmosphere, the air/fuel ratio and thus flue gas composition can change over time. In order to minimize the risk of intoxication (see also chapter 5333), explosion and pollution real (uncontrolled) fuel burners are adjusted to operate far beyond this limit in the excess (lean mixture) region. However, unfortunately effi- 

The aim of this chapter is to give an overview of commercially available gas sensing techniques with a focus put on sensors in the lower price range which are suitable for combustion control. 

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