A modern boiler flue gas analyser is an electronic instrument designed to measure the concentration of specific pollutant gases in the waste gas from a boiler, together with the air inlet and outlet temperatures. The gases measured by the boiler flue gas analyser vary, but they usually include oxygen, carbon monoxide and nitric oxide. The oxygen is not really a pollutant, but the boiler flue gas analyser uses this as a measure of the excess air in the system. Although excess air is essential for combustion, since it is not possible to mix fuel and air completely perfectly, excess air is the main source of losses, since this heated air is simply vented to atmosphere and wasted. For this same reason, the air inlet temperature and the temperature after the last heat exchanger give a measure of just how much energy has gone unnecessarily to atmosphere. The smaller the difference between the two readings, the more energy has been extracted.
The boiler flue gas analyser calculates these effects automatically and gives a value for the thermal efficiency of the boiler. It can also use the carbon monoxide reading to correct this value for losses caused by incomplete combustion. It is almost inevitable that some carbon monoxide will remain in the gas stream, unless the value of excess air is very high.
A boiler flue gas analyser is an essential tool for making any adjustments to a boiler combustion system. It allows the operator to see the effects of changes in real-time, and not after having a sample analysed in a laboratory. These instruments are now very much lower in price than twenty years ago, and lie well within the budget of any heating company. The ability to set the combustion point of a boiler with accuracy every time will outweigh any costs that may be involved with the boiler flue gas analyser, be they purchase or maintenance.
Since many boilers and larger burners must now be regularly tested for efficiency and pollution control, it is essential to be certain that your own equipment is working within the legal limits. Failing at a control measurement may well lead to expensive fines or even more expensive time when the boiler may not be used. EPA compliance testing is naturally the field where the boiler flue gas analyser comes into its own. This is exactly what it was designed to do.
Competition has now led to an increase in the number of companies producing this equipment and it is quite possible to find a cheap flue gas analyzer these days.
The boiler flue gas analyser has been on the market for many years now, but the popularity has only recently increased due to the introduction of compulsory testing in many countries and the increase in the cost of fuel. They are known by a number of names, such as combustion gas analyser, flue gas analyser, combustion analyser or simply stack analyser.