Method of controlling the gasification of solid fuels in a rotary-grate gas producer

A method of controlling the gasification of solid fuels in a reactor under a pressure from 10 to 100 bars in a mixture of gasifying agents, which comprise water vapor and oxygen, wherein the fuel in the reactor constitutes a fixed bed, which slowly descends, the mixture of gasifying agents flows into the fixed bed through a rotary grate and through an ash layer provided on the rotary grate, and ash is withdrawn under the rotary grate, characterized in that a first pressure (p1) is measured in the reactor below the rotary grate, a second pressure (p2) is measured in the reactor adjacent to the top of the ash layer, the pressure difference (p1-p2) which is calculated from said pressures is compared with a setpoint, which is associated with the instantaneous ratio of water vapor to oxygen in the mixture of gasifying agents, said ratio is increased when the pressure difference is insufficient and said ratio is decreased when the pressure is excessive.