NOVELTY - Gasification of the solid fuel with the low calorific value involves a preliminary gasification carried in a pyrolysis chamber externally heated by gas produced in the gasification process, where a gasifying medium is passed cocurrently or countercurrently through the biomass, and the reactivity and humidity of the solid fuel is assessed prior to its introduction into the pyrolysis chamber.    USE - For gasification of the solid fuel with the low calorific value, particularly of the biomass with the wide spectrum of humidity (claimed).    ADVANTAGE - The method for gasification of the solid fuel, particularly of the biomass contains large dispersion of humidity, thus gasifies the biomass in a single process and in a single gas generator, after prior fuel reactivity and humidity assessment, on the basis of which the conditions of gasification are selected, dependent on whether the fuel humidity exceeds 30%. The gas generator supplies two gasifying media on different steps of the pyrolysis process and feeding of % fuel to the top pyrolysis chamber inlet which greatly facilitates the loading of the pyrolysis chamber and prevents malfunctions. The height of the bed is controlled during the process and maintained at a level dependent on humidity and reactivity of the biomass.    DETAILED DESCRIPTION - Gasification of the solid fuel with the low calorific value, particularly of the biomass with the wide spectrum of humidity involves using a preliminary gasification in the pyrolysis chamber externally heated by gas produced in the gasification process, where gasifying medium is passed cocurrently or countercurrently through the biomass, where a prior assessment of reactivity and humidity of the solid fuel is made using the known methods then fuel is introduced through the upper inlet (2) into the pyrolysis chamber (1), located vertically centrically in the external chamber (3), where fuel is subject to drying and pyrolysis under an influence of heat supplied through the wall of the pyrolysis chamber and subsequently a residue of the pyrolysis process in the form of the solid bed collected in the lower part of the gas generator in the space above the slot grate (4), which height is maintained on a level dependent on humidity and reactivity of fuel, is gasified by gasifying medium feeded under the slot grate, when using fuel of humidity greater than 30%, if the height of the solid bed is lower than the distance between the end of the pyrolysis chamber and the lower edge of the slot grate and when using the solid fuel of humidity lower than 20%, gasifying medium is feeded through gasifying medium nozzles, located in the wall of the pyrolysis chamber on the height of the chamber, determined on the basis of fuel reactivity measurement and subsequently, an additional stream of gasifying medium is feeded through the slots of the slot grate into the residue in the form of the bed, located between the slot grate and the pyrolysis chamber outlet/burning the remaining coal element, moreover when using the solid fuel of humidity of 20-30%, gasifying medium is feeded both through gasifying medium nozzles, located on the wall of the pyrolysis chamber and under the slot grate, in the amount proportional to the fuel humidity and the controlled pyrolysis process speed. An INDEPENDENT CLAIM is included for gas generator for gasification of the solid fuel with the low calorific value, particularly of the biomass with the wide spectrum of humidity comprising a fuel feeder, the pyrolysis chamber with the slot grate, a preliminary degasser of fuel, the lower air box, where the pyrolysis chamber, preferably in the form of the vertical pipe with the upper fuel inlet is located centrically in the external chamber, preferably in the form of the vertical pipe, the lower part of which, constitutes the air box in an inside of which, below the end of the pyrolysis chamber pipe, there is axially built-in the slot grate in the form of a truncated cone of an inclination of the wall in relation to the plane under the angle of 20-80 degrees under which there is situated a chamber of ash receiving, the lower part of which, is installed in a water seal tank (6), moreover, gasifying medium nozzles are located in the pipe wall of the pyrolysis chamber located on the height from the lower edge of the slot grate, where the number of gasifying medium nozzles and the total area of the nozzle openings and the height, on which they are located, depends on the type and granulation of fuel and is established using the separate methods, preferably by experimentation.    DESCRIPTION OF DRAWING(S) - The figure shows schematic view of the gas generator for gasification of the biomass.    Pyrolysis chamber (1)    Upper inlet (2)    External chamber (3)    Slot grate (4)    Water seal tank (6)