Abstract: Method for producing hot drying gas by a burning flowable biological refuse in an incinerator which comprises a vertical cyclone furnace. Fuel together with primary combustion air is tangentially injected into the vertical cyclone furnace, and secondary combustion air and tertiary combustion air are injected into a throat. A cooled rotating ash scrapper is provided in the bottom of the vertical cyclone furnace and waste gas is conducted through the throat to a secondary combustion chamber in which an incineration of residuals takes place and from which a drying gas is removed. A combustion retarding gas is injected into the hottest area of the vertical cyclone furnace so that a sintering and the formation of slag is avoided.