For a client looking for an economical solution, Wellons FEI builds an air cooled, fixed grate system for applications using biomass with low moisture content (less than 30%) and low ash content (less than 0.5%). The advantages of this system are low cost and ease of operation. Fuel is fed to the combustion chamber and falls onto a fixed grate.
The grates used in the Wellons FEI grate system are all made of a special high grade stainless steel casting. Most manufacturers will use cast iron grates that you have to change out every few years. Wellons FEI has standardised on stainless steel grates that will last 4 to 5 times longer than their cast iron competitors. Combined with the air cooling effect of the primary air plenum, the grate does not require any water cooling circuit; thus minimizing total system maintenance.
Primary air is forced into a plenum underneath the grate in order to promote gasification. The secondary air nozzles are high velocity jets placed on top of the grate that cut across the combustion chamber in order to complete oxidation of the gases leaving the grate.
When the size of the combustion units is transportable, Wellons FEI pours the refractory inside its combustion chambers in the shop. Field installation time can be cut back considerably by having the refractory installed in the shop as Wellons FEI does. Most vendors have the refractory installed on site were quality assurance can become an issue. Most of the time vendors will supply their systems and pass the cost of the refractory as an on site installation costs. This is not the case with Wellons FEI, all of our refractory is shop poured complete with expansion joints and anchors. Refractory service temperature is 3200 F, well above the typical 1800F seen in biomass combustion systems.