NOVELTY - A gasification channel (3) is implemented as a series of chambers. An auxiliary burner (9) supplies external heat to this channel, during biomass gasification. A pre-pyrolysis tube precedes the gasification channel and an ash extractor follows it. Gases generated are re-gasified in the gasification channel, whilst material to be gasified is carried mechanically from a supply container to ash extraction. Both the pre-pyrolysis tube and the gasification channel are equipped with a jacket supplying external heat. This is located largely below the respective processing channel and surrounds it.    USE - A pyrolytic gas generator supplied with biomass, e.g. wood or oil seeds, to produce gas used for heat and power generation    ADVANTAGE - The new gas generator is easily operated and efficient. The gas produced is used in combined heat and power (CHP) plant. Suitable feedstocks include rape, pressed cake and other biomass. Multi-chamber construction of the gasification channel ensures optimal conditions at all stages of gasification. Heat is supplied uniformly around the processing channels. Guide vanes optimize heat transfer from the hot gases, into the material being gasified. The coke filter assures a high degree of gas cooling and purification. Its gas supply and offtake arrangements ensure free flow of gas, minimizing coke particle entrainment into the purified gas. All contaminated coke from the filter is re-used by gasification. Any incompletely-gasified material is returned to the start of the process.    DETAILED DESCRIPTION - The heat supply channel is arranged below the processing channel. At the end remote from the auxiliary burner it transitions into a channel surrounding the processing channel. Guide vanes are provided on the gasification channel and/or pre-pyrolysis tube. These project out into the heat supply channel. The pre-pyrolysis channel and/or gasification channel contain a mechanical conveyor e.g. a conveyor screw (18), for steady transport of the material being gasified. A coke container (16) is filled with coarse coke. The gas produced is passed through this, to filter and cool it. There is a single gas line in the cover of the container, above the coke packing. A number of pipes low down in the container, form the gas inlet. Equipment is included to supply contaminated coke to the gasification channel. At the end of the gasification channel there is an extractor for incompletely-gasified material. A feed unit returns such material to the start of the gasification tube. A feed unit returns extracted material to the coke vessel. A screen (19) separates-out small particles of incompletely-gasified material, before feeding the oversize material to the coke container. A unit supplies screened-out fines to the outlet of the coke container. The hot gas filter is connected to the end of the gasification channel. This removes fine residues from the fuel gas, comprising entrained ash and dust. The filter is ceramic and contains numerous channels. It is equipped with a cleaner. This is formed by gas nozzles which blast the filter intermittently with pressurized, purified fuel gas. A tube heat exchanger is used for cooling. Rotating brushes inside it, remove condensed oil, tar, water and other deposits. They are carried off to an interception unit. The brushes have a spiral shape and/or the tube arrangement is vertical. A scrubber washes the gas using an oil spray. This contains rotating oil nozzles. They are surrounded by a spinning rotor. The gas is introduced into the space between nozzles and rotor. A droplet separator removes oil spray from the fuel gas. Mutually-offset, optionally-angled impact baffles, separate the oil mist contaminated with impurities, leading them off to an oil storage tank. A filter insert is connected after the gas scrubber. The droplet separator is coaxial with the oil scrubber. The contaminated oil is fed to the auxiliary burner. A safety device prevents the danger of flashback to the gas generator. The fuel gas is passed through a water bath.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic side elevation of a gas generator.    gasification channel (3)    feed shaft (7)    auxiliary burner (9)    conveyor screw (15)    coke container (16)    conveyor screw (18)