Dynamic modelling, experimental validation, and thermo-economic analysis of industrial fire-tube boilers with stagnation point reverse flow combustor

In the first part of the present work, a detailed dynamic model of fire-tube boilers equipped with stagnation point reverse flow (SPRF) combustor is implemented. Experimental data, obtained through a testing procedure, are then employed to validate the developed model. Several boiler configurations with different sizes are next considered and a PID controller is subsequently tuned for each boiler model. In the next step, the dynamic behaviour of the considered boilers, while addressing different steam demand profiles, is simulated and the corresponding overall efficiency is determined. A comprehensive economic analysis is then conducted in order to choose the most suitable boiler model for each profile, taking into account both the corresponding fuel consumption and the required initial investment. The obtained results demonstrate that, beyond a certain size, increasing the dimensions of the boiler leads to a negligible increment in the efficiency. Accordingly, boiler No. 2, which is a notably smaller unit compared to the other configurations, is determined to be the most economically promising choice. Furthermore, the pressure variations of the steam supplied by different configurations have also been studied. The obtained results demonstrated that utilizing larger boilers leads to an insignificant reduction in the amplitude of pressure deviations and does not have any effect on duration of these variations. Therefore, the provided results can be utilized to choose the most economically suitable size of the boiler, considering the customer's consumption profile, while guaranteeing that the specifications of the customer in terms of acceptable pressure deviation of the supplied steam are also addressed.