|What “Efficiency Testing” Means in Boilers|
|Written by D. R. Wulfinghoff|
|Wednesday, 09 June 2010 09:13|
Page 1 of 5
What “Efficiency Testing” Means in BoilersEfficiency is defined as the ratio of the useful output energy produced by a system to the raw energy input into the system. In principle, it is possible to test the overall efficiency of a boiler plant. You could do this by measuring the energy content of the steam or hot water that is exported by the boiler plant and the total quantity of energy that is input to the boiler plant, including fuel for the boilers and other energy for the auxiliary equipment.
In actual boiler plants, such a comprehensive test is impractical. Measuring steam or hot water energy with reasonable accuracy, say within one percent, is possible only under laboratory conditions. Field measurements of flow are vulnerable to error, even if they are done by expensive consultants. Measuring input energy is also subject to error. You would have to analyze the energy content of your fuels, make corrections for ambient conditions, and create very stable test conditions. This is not possible under realistic conditions.
Fortunately, you don’t need to measure the total efficiency of a boiler plant if your objective is to tune up the plant’s efficiency, rather than running a testing laboratory. You can use an easy procedure, called a “combustion efficiency” test, to measure the aspects of boiler efficiency that cause most losses in normal operation. The “combustion efficiency” test determines how completely the fuel is burned, and how effectively the heat of the combustion products is transferred to the steam or water.
The efficiency of the other boiler plant components, such as pumps, fans, and motors, tends to remain constant, so you don’t need to test their efficiency on a continuing basis.
Limitations of the Combustion Efficiency Test
The combustion efficiency test is your primary tool for monitoring boiler efficiency. You can achieve accuracy in the range of one percent of efficiency if you do the testing carefully and use equipment of good quality. However, be sure that you understand what the test is telling you. The combustion efficiency test does not account for: