II. Combustion
The combustion system (03.) is designed as an inclined grate furnace with water-cooled feed cone and grate side cooling.
Biomass is carried inside the furnace by a moving grate, where combustion is controlled by the the fuel feed rate and the supply of combustion air by three fans. The primary and secondary fans (08. & 09.) of the recirculation system placed before the chimney, recirculate flue gas in order to maintain optimal combustion parameters inside the furnace.
Precise combustion control is essential particularly when dealing with agricultural fuels which are typically characterized by aggressive chemical composition and low ash melting points. Even when the temperature inside the furnace needs to be maintained below 1000° in order to avoid ash melting and system damage, VAS moving grate system combined with precise combustion control and longer retention time of the combustion gas in the secondary and afterburning area of the furnace, deliver complete fuel combustion, high efficiency and low emissions
Several safety features are integrated in VAS' combustion system. In addition to a vertically arranged refractory-lined hot gas shaft right after the furnace, an emergency chimney (04.) placed on top of the combustion chamber will automatically release the heat from the furnace into the atmosphere if a failure in the thermal oil system is detected. The emergency chimney includes a hot gas resistant flap and opens under its own weight to safeguard against an event of loss of power.