Improving the performance of boiler by reducing heat loss using soot blower
The main objective of this investigation is to improve the performance of the boiler. A boiler is said to be efficient, if it converts all the chemical energy in the fuel into heat energy and also transfer them fully to the incoming water. The incomplete combustion of the fuel and the incomplete transfer of heat to water, are grouped together as ‘heat losses’. It is therefore necessary that these losses should be minimized to make the boiler more efficient. Among the heat losses one of the major heat losses is due to fouling. Ash fouling on heat transfer surface has always been one of the main operation concerns in coal fired power plant utility boilers. In many power plants, high pressure and high temperature steam are always used to blow away the ash fouling and a number of soot blowers are continuously initiated according to pre-defined sequence on a fixed schedule. However, complete cleaning is not achieved by the soot blower because it is unable to access all the areas of the tubes. During the ash removal, the soot blower lance rotates and extends through a small opening in the boiler wall while blowing high pressure steam over the tubes. But the nozzle position remains same during both extension and retraction of the lance tube, so that the ash removal takes place only on the particular area not over the entire area of the tube. By making the soot blower rotate to different positions better cleaning can be achieved. By using PLC, calculated delay time is given for the lance tube to change its position from 0 to 600 then the lance tube will retract from the adjusted angle (600) in the anticlockwise direction. So that is able to clean the areas which were not cleaned during the forward motion of the lance tube. Then, during next stoke the nozzles start to rotate from 600 in the forward direction and retract at 1200 in anti-clockwise direction. Thus better cleaning can be achieved. When fly ash is removed properly better heat transfer takes place which results in increased in boiler performance.