Calculation methods of steam boiler operation factors under varying operating conditions with the use of computational thermodynamic modeling

Paper presents the results of pulverized coal-fired steam boiler analysis under varying operating conditions. To investigate the efficiency of the analyzed steam boiler, the energy and exergy analysis was conducted, as well as the basic operating conditions of the flue gases-air and water-steam circuit were determined. To calculate boiler energy efficiency, the indirect method and individual boiler losses computation was applied. The thermodynamic model was developed to simulate boiler operation under partial boiler loads. The accuracy of the model results was verified at three different partial loads. The thermodynamic model was created using Ebsilon Professional software and a 0-dimensional thermodynamic modeling approach. The results in the form and steam temperature distributions at the outlet of all heating surfaces have been verified with available boiler measurement data. The relative error of steam temperature calculation doesn’t exceed 4.5%. The developed model allows performing calculations for variable input conditions in order to determine the basic parameters of the boiler operation and total boiler efficiency. The presented calculation methods were applied to identify the changing of boiler efficiency and basic boiler parameters during operation with under different partial loads and during the burning of different coal types. The various operating conditions have a great impact on boiler performances. Energetic and exergetic analysis carried out for boiler operating parameters were used to evaluate total boiler efficiencies. The results were presented in the form of total boiler efficiency and boiler losses as in the function of boiler load and calorific fuel value.