Validation and simulation of furnace exit gas temperature and modelling of furnace slag thickness of oil fired boiler of power generating steam turbine

This paper discusses on the study of validation and simulation of the furnace exit gas temperature and modeling of furnace slag thickness of oil fired boiler of power generating steam turbine unit of 323 MWe. Furnace exit gas temperature is an important operational boiler parameter. Its continuous monitoring and controlling is crucial to get reduction in fire side corrosion and fouling of furnace. Thermodynamic heat and mass balance model was developed to validate the furnace exit gas temperature measurement of the newly installed Infrared sensors at furnace exit. Furnace exit gas Temperature validation was performed at minimum and rated loading conditions of the boiler. The difference between measured and calculated furnace exit gas temperature was in the range of ± 20°C. Fifteen variables of boiler including steam turbine were selected at different operating conditions of the boiler to perform the simulation study of furnace exit gas temperature by using Excel solver module. The temperature difference of measured and simulated temperature remained within ± 5°C at minimum and rated loading conditions of the boiler due to strong statistical co-relation among the selected variables. Modeling of furnace slag thickness was done in relation to the increase in furnace exit gas temperature. Analysis shows that 15 mm thick layer of ash deposit on furnace walls can increase furnace exit gas temperature by 149°C. Sensitivity analysis of furnace exit gas temperature at boiler rated loading condition was also performed in-order to analyse the impact of boiler crucial parameters on furnace exit gas temperature.