Combustion system should be undertaken completely; if not, combustion process will remain combustibles in flue gas such as hydrogen and carbon monoxide. Determining quantity of combustibles in flue gas is necessary to evaluate combustion efficiency. Generally there are some ways to determine quantity of combustibles:
1. Use detector for catalytic combustibles
This detector is usually used for parking garages and mining area and the function is for discover combustibles gases in the air. In the case of flue gas, the detector use platinum as its catalyst element. Platinum catalyst is used to coat active element, while inert binder coat reference element.
Temperature of platinum catalyst is controlled approximately 400 F. When the detector is contacted with flue gas flow which has temperature above 400 F, will cause adding heat transfer to active element. This is occurs because the sensor had made the combustibles was burned when combustibles making contact with platinum catalyst.
Determining quantity of combustible in flue gas is taken from sample of flue gas passing through the detector. The quantity is proportional with the changes electrical resistance of two elements because of adding heat as explaining above.
2. Use wet electrochemical cells.
Wet electrochemical cells are used to determine quantity of carbon monoxide not hydrogen. Ionization will occur when carbon monoxide pass this detector through the membrane and making contact with cathode and anode. The ionization will produce difference voltage. The changes of voltage are proportional with the quantity of carbon monoxide.
3. Use no dispersive infrared absorption.
Light waves are used to determine the presence of carbon monoxide because the character of this gas can absorbs infrared energy of the specific wavelength. This energy is determined with the detector which can be called as spectrophotomer.