Support of biomass boiler control design by modeling

Abstract

Most of small-scale combustion devices firing biomass use control algorithms designed on the basis of an empirical experience. Very often, the on-off strategy is applied for heat output control linked with repetitive starts of the burning process which may be linked with some undesirable effects especially as far as emissions and efficiency are concerned. There are more reasons why such control solutions are preferred in practice, but one of the most evident is the difficulty of modeling biomass combustion processes which are strongly dependent on the fuel properties and its variability. Appraisal of both model based and model free methods in the controller design was the object of investigations we carried out on an experimental small scale water heating boiler firing wood chips of various quality. Results from testing suitability of a model intended for both simulation and control design are reported in this paper completed with some other pieces of knowledge from ecological operation of biomass boilers. Usage of the model will be demonstrated on the model-based control algorithm.