Hydrogen damage in water wall tube boiler of coal power plant

Abstract

Boilers have an important role in steam power plants in Indonesia. In the operation of a boiler failure often occurs, especially in the area of the water wall tube. Water wall is one component where water gets warmed up from the combustion chamber and changes its phase from liquid to steam. Water wall pipe damage that occurs in the form of a leak that is brittle and without accompanied by thinning of the pipe wall. From the results, composition testing is known that this water wall pipe is carbon steel with SA 210-A1 specifications. Metallographic results show that the microstructure of this material is ferrite and pearlite with a banded structure. On the results, metallography is also shown by the presence of voids and microcrack that appears on grain boundaries. On hardness testing, it is known that the inner and middle of the tube has decreased the average hardness of 120 Hvn. On the outside of the tube, the value of hardness is still averaged 140 Hvn. From SEM analysis, it can be seen that the deposit is quite thick on the inside of the tube which reaches 200 microns. A decrease in boiler water quality is one of the causes of leakage and hydrogen damage