There have been many developments in the field of combustion technology in the last few years. This is especially true for gas burners. The newest gas burners are of the condensing type, where the flue gas temperature is below the dew-point of the gases, which lies by about 57°C for flue gases from gas burners. The water in the gas condenses on a set of special heat exchangers mounted in the gas stream. This enables the evaporation energy to be extracted from the gas as well, raising the efficiency greatly at no extra cost.
Care has to be taken to use corrosion-resistant materials, since the condensate is relatively aggressive and the flue channel has to be fitted with a stainless steel liner or equivalent, otherwise it will be destroyed fairly quickly.
The traditional calculation of combustion efficiency uses the temperature of the gases at inlet and in the stack for the calculation. A separate correction must be made to take account of the specific heat of evaporation when working with condensing equipment. This correction is of interest for the owner of the equipment, but may not be accepted officially as a measure of efficiency. Regulations in most countries specify how these parameters should be calculated and may not allow a different method.
Another new and related matter is carbon monoxide detection in and around the burner. This can be done with the same basic equipment if the hardware and software is prepared for the job.
As has been discussed above, the function as an air pollution control device is just part of the job carried out by this equipment. A flue gas analyser is even more necessary with the modern equipment. The operating data often specifies the adjustment of the burner in terms of the waste gases and it is simply not possible to adjust it in any other way. The adjustment of a condensing boiler for high efficiency is very critical. Condensation should occur in as much of the range as possible, without losing the capability to reach maximum ouput when necessary.
Flow measurement to determine the exact quantity of pollutants produced is becoming more common. Many instruments are being equipped for this purpose now. Flow measurement allows the total level of pollution to be calculated. As has often been said: you can't eat a percentage, and this is just as true in reverse when talking about pollution. A cigarette lighter produces a very high level of carbon monoxide, but the total quantity is minimal. There have therefore been no serious attempts to limit the emissions from cigarette lighters! As can be seen from the linked pages, flow measurement has some aspects that make it more complicated than might appear at first sight, but the result is essential to know the amount of pollution that is produced yearly or monthly from a specific stack. Again, these methods were common for stationary equipment for a long time before being applied to portable instruments, but such additions increase the range of operation for the equipment and also provide an alternative should the CEMS be out of operation for maintenance or other reasons.