Abstract

In a wood-pellet cogeneration unit comprising a pellet feed, a combustion chamber, an ash removal device and a stirling engine, in order to achieve an optimum efficiency, provision is made for an exhaust gas recuperator (11) to preheat combustion air (10) and for wood pellets to be gasified with a portion of this hot air (13), for this portion (13) of the hot combustion air (10) to be directed above a grate (4) into a gasification combustion chamber (3 a) and for the fuel gas (18) thus produced to be sucked downwards through the grate (4) together with the ash by a side channel blower (7), for the fuel gas (18) under the grate (4) to be displaced with a flow impulse of the rest (14) of the hot combustion air (10) in such a way that, firstly, a low lambda value close to the CO limit is maintained and, depending on the temperature of the combustion chamber (3b), the combustion at a central nozzle (19) is stabilized, or, with increasing temperature of the combustion chamber (3b), the state of flameless combustion increasingly appears, wherein a potential vortex (20) is produced in the combustion chamber (3b), said potential vortex (20) intensively mixing exhaust gas (6), fuel gas (18) and hot combustion air (14), such that fuel gas (18) and ash particles burn completely.

IPC Classes  ?

• F23B 50/06 - Combustion apparatus in which the fuel is fed into or through the combustion zone by gravity, e.g. from a fuel storage situated above the combustion zone the fuel forming a column, stack or thick layer with the combustion zone at its bottom the flue gases being removed downwards through one or more openings in the fuel-supporting surface
• F23B 50/12 - Combustion apparatus in which the fuel is fed into or through the combustion zone by gravity, e.g. from a fuel storage situated above the combustion zone the fuel being fed to the combustion zone by free fall or by sliding along inclined surfaces, e.g. from a conveyor terminating above the fuel bed
• F23G 5/027 - Methods or apparatus, e.g. incinerators, specially adapted for combustion of waste or low-grade fuels including pretreatment pyrolising or gasifying
• F23G 5/46 - Recuperation of heat
• F23G 7/10 - Methods or apparatus, e.g. incinerators, specially adapted for combustion of specific waste or low grade fuels, e.g. chemicals of field or garden waste
• F23L 15/00 - Heating of air supplied for combustion