New Intelligence in Instrumentation of Solid Fuel Power Plants

Large variations in the moisture content and heat value of the fuels (peat, bark, coal, etc.) can cause stability problems in the combustion. We have developed some computer based methods to improve the measurement and control of solid fuel boilers. A microprocessor based four-beam infrared moisture measurement system has been developed, which has advantages compared with ordinary two-beam sensors. The paper presents also a digital measuring station for estimating the fuel power of the plant. The flame monitors might give a "flame off" indication even if the fuel is still burning. The system we have developed estimates the changes of the combustion process by comparing the amount of flue gases generated in the process with the fuel and air feed. By adding this information to the signals obtained from the flame monitoring system the existence of the flame can be verified. The load level and combustion conditions in industrial power plants vary continuously, and when solid fuels are used, the optimal excess air in the flue gas does not stay constant. We have developed and tested a method for minimizing the losses of the boiler.