Abstract: In order to burn a fuel of low ignition properties and low contents of volatile gases in steam generators: the combustion air is introduced in three batches at three successive places into the firebox. Preferably, the primary air is introduced at a temperature of at least about 500.degree., preferably between 500.degree. and 600.degree. C. so as to effect a pregasification of the fuel. The secondary air is then introduced at a temperature of about 350.degree. to 400.degree. C. to start the combustion of the pregasified fuel and the tertiary air is finally introduced at a temperature of only about 250.degree. to 300.degree. C. in order to complete the combustion. This temperature differentiation of heat ranges then will permit to withdraw theash as a dry discharge.

Abstract: A blower-beater mill for drying and milling material with a beater body and impeller arranged on the mill shaft. The beater arms of the beater body are fastened between hub rings on the shaft and water cooling is applied along the longitudinal axis of the mill shaft. The shaft is enclosed by a casing which extends to the impeller and is spaced from the shaft. In the region of the beater body, the casing has openings for the beater arms. The mill shaft also has hub rings between the beater body and the impeller. The casing is made up of U-shaped rings which overlap one or several hub rings. The rings have vertical legs inserted into passages between the hub rings. A passage behind the beater portion may be enlarged for fitting insert pins in the direction of the hub pins and lock washers may be placed between the front faces of the insert pins and the side faces of the hub rings. A gap may be located between the deflection disk of the impeller and the last U-shaped ring.

Abstract: A blower beater mill for grinding and drying operations in which a rotor is provided with a beater portion located on the mill shaft and has also a fan impeller. Beater arms of a beater portion are fastened between hub rings of the mill shaft. The shaft is water-cooled along its longitudinal axis. Shaft crests of the hub rings are enclosed by a jacket at a spaced distance therefrom. The jacket is made of individual rings through which the beater arms pass. The width of these rings is slightly larger than the spacing between two adjacent rows of beater arms. The rings, moreover, overlap in the area of cutouts of the beater arms. The rings may have U-shaped profiles with vertical legs inserted together with the beater arms into grooves between the hub rings. The space between two adjacent U-shaped rings and two adjacent beater arms, located within one beater arm row, is covered by sheet metal connected to the rings and the beater arms.