The steam generation system consists of a shell and tube boiler that is supplied with hot air from a Dutch Oven, equipped with step grate furnace. The feed rate of timber waste that is fed into the furnace to fuel the combustion process, is controlled by a variable speed drive. Inside the boiler the hot gas generated in the Dutch Oven is sucked through a series of boiler tubes by an induced draft (ID) fan. Energy is transferred from the hot gas to the water that surrounds the tubes to produce steam. The volume of hot gas flowing through the boiler is controlled by using a variable speed drive on the induced draft fan. The hot exhaust gas leaving the boiler flows through a multi cell grit arrestor and the ID fan before it is exhausted into the atmosphere through a chimney.
Furnace temperature, air outlet temperature and boiler pressure are monitored by the control system to adjust combustion conditions in the furnace. The TFD boiler control system manages the fuel and air supply to the combustion chamber ensuring optimum combustion conditions. The combustion controller is designed to keep steam pressure constant as the boiler load changes by varying the firing rate in proportion to the steam demand.
Both the TFD kilns and TFD boiler control system is PLC based and is linked to a SCADA system that runs on a computer.