Abstract: The bed depth in a power plant burning sulfur-containing fuel in a fluidized bed of material which constitutes a sulfur absorbent in a combustion chamber is controlled on the basis of plant power output. A plurality of sensors connected to the combustion chamber determine the existing bed depth. A bed material mill grinds material removed from the bed prior to returning it to the bed, the rate at which the mill operates being controlled by the extent to which the actual bed depth differs from the desired bed depth. The mill grinds some bed material to small enough size for it to be carried from the combustion chamber with the combustion gases.

Abstract: In a fluidized bed plant for the combustion of impure solid fuel in the presence of an absorbent material which absorbs and neutralizes the impurities, in particular sulfur, the supply of absorbent material to the fluidized bed is controlled in dependence on the impurity content in the exhaust gases leaving the fluidized bed. To achieve a rapid control, at least part of the absorbent material is supplied to the fluidized bed in a finely ground state. The bed material may consist of coarse-grained absorbent material or a chemically inactive material, or a mixture of these. Coarse-grained absorbent material which is discharged from the fluidized bed can have its particle size reduced and be passed back to the fluidized bed.

Abstract: A machine of introducing sound-insulating members of a resilient material at predetermined places in concrete beams formed by a lower concrete element, preferably coffer-shaped, and an upper concrete element in the form of a slab. The machine comprises means to raise the upper element from the lower element so as to form therebetween a gap intended to receive the sound-insulating members, means to sense the vertical dimensions of said gap, means to cut off a piece of insulating material the vertical dimensions of which agree with those of the gap, means to apply an adhesive to said member, and means to position said member in the gap in the predetermined position. The invention ensures that the total thickness of concrete beams including such a sound-insulating layer is equal for all beams thus composed irrespective of the individual thickness of the discrete concrete elements.