Abstract: A method is proposed for recovering high-temperature exhaust gases of high inflammability in terms of carbonaceous concentration from the partial combustion, at atmospheric pressure or near atmospheric pressure, of a mixture of pulverized bituminous or subbituminous coal and air as oxidizer gas, enriched with oxygen gas in a combustor apparatus having a cylindrical combustion chamber with a tangential injection duct, through which the fuel mixture is introduced into the combustion chamber to develop into a rapidly swirling vortex optimizing burning over a short period of time. As a result, the high-temperature, inflammable exhaust gases are generated, of which the heat is recovered to produce steam in a boiler. After losing portion of their heat to the boiler, the inflammable gases, following purification by a filter and desulfurization unit, recovery for subsequent thermal use in boilers, metallurgical or other chemical processes.

Abstract: The air flow rate of a fan driven by a motor controlled by an adjustable speed control equipment is automatically controlled by stopping the adjustable speed control equipment in response to a fault signal therefrom during operation with an inlet vane installed upstream of the fan in fully open state, simultaneously throttling the inlet vane at a preset speed to a degree of opening appropriate for the load by means of a control circuit, and, after a period for reduction of residual voltage of the motor, changing over to operation of the fan by a commercial power supply thereby to shift to control by the degree of opening of the inlet vane.