Implementation of a multi-setpoint strategy for fire-tube boilers utilized in food and beverage industry: Estimating the fuel saving potential

The present work aims at estimating the fuel saving potential of implementing a multi-setpoint control strategy for a fire-tube boiler that addresses a steam demand with a notable (daily) variation in the requested pressure level. The daily steam consumption profile of an Italian cheese factory is accordingly considered as the case study. Next, a dynamic PID controller is developed and tuned, aiming at enhancing the boiler's controllability at partial load conditions (in comparison with a traditional PID controller). In the next step, a multi-setpoint strategy is implemented, in which the pressure setpoint (following the desired pressure profile) is dynamically modified. The yearly fuel consumption of the boiler is then determined and is compared with the consumed fuel while employing the currently utilized constant-setpoint approach. The obtained results demonstrate that employing the proposed strategy results in reducing the yearly fuel consumption by 4.5%. The approach that is proposed in the present study can be employed by many steam end-users in the food and beverage industry, specifically in Italy, whose needed pressure level is highly variable.