Abstract
The influence of firing Victorian brown coal on high temperature corrosion of boiler tubes was investigated in comparison with bituminous coal and the mix of the brown coal and the bituminous coal by combustion tests and laboratory immersion tests. The combustion tests were carried out using experimental furnace installed sample tubes with internal air cooling to simulate superheater tubes. Both the degree of corrosion of the tubes and the content of sodium sulfate and chloride in ash deposit on the tubes were highest in firing the brown coal. The immersion test revealed that sodium sulfate and chloride in synthetic ash both promoted the high temperature corrosion, indicating that sodium sulfate and chloride in deposit were the main factor of the corrosivity of brown coal. In firing the 1:1 mix of bituminous and brown coal, corrosion of the tubes was almost the same level with the bituminous coal and constituent of the ash also was nearly the same as the bituminous coal due to low ash of the brown coal. It was concluded that mixing brown coal with bituminous coal was effective in mitigating high temperature corrosion due to brown coal.
