In this article a simple model for the grate combustion of
biomass is derived from physical considerations on the basis
of a pilot scale furnace of the research centre BIOENERGY
2020þ (depicted in Section 4). An intensive literature review
(Section 2) was conducted as a basis for further model development.
It showed that experts assume two completely
different burning behaviours for grate combustion countercurrent
with ignition at the top of the bed and co-current with
ignition at the bottom of the bed (see Fig. 1).
It is obvious that the dynamic behaviour is completely
different for the counter-current and co-current case. Prior to
modelling, it is therefore important to determine the present
combustion situation at the pilot scale furnace investigated
(see Section 5.1). Based on the insight gained into the basic
combustion situation, a simple model for co-current
combustion (ignition at the bottom of the bed) is derived
(Section 3). The model is based on two mass balances for
water and dry fuel, in which results of both literature search
and experiments are considered.
Finally, the model was verified by appropriate experiments
at a pilot scale furnace with horizontally moving grate at full
and partial load (Section 5.2).