Abstract: A method for adjusting a supply of gaseous medium to a fluidized bed boiler performing a combustion process and including a pipe grate comprising a plurality of pipes. An active area of the pipe grate is adjusted to form at least one inactive bed area that is out of use by shutting off the supply of gaseous medium to some of the pipes of the pipe grate utilizing pipe-specific control means included in at least some of the pipes of the pipe grate. Cooling medium is conducted through cooling channels located in the pipes in the at least one inactive bed area at least during the combustion process.

Abstract: In a method in connection with a pipe grate (2) for a fluidized bed boiler, air or a corresponding gaseous medium is supplied to the fluidized bed boiler through several pipes (8). The active area of the grate, in which the supply of air or the like to the pipe grate takes place, is adjusted with pipe-specific control means (10) which are included in at least some of the pipes of the pipe grate (2).

Abstract: A method for supplying a gaseous medium to a fluidized bed boiler through several pipes of a pipe grate. An active area of the grate is adjusted with a pipe-specific control included in at least some of the pipes of the pipe grate. A supply of gaseous medium to the pipe grate takes place in the active area. The active area of the grate is reduced by forming at least one inactive bed area that is out of use.

Abstract: A grate assembly for a fluidized bed boiler is provided. A number of parallel sparge pipes extending substantially in the horizontal direction and are provided with devices for supplying fluidizing air from within sparge pipes into a combustion chamber located above the grate assembly. The discharge of coarse material is effected through an aperture system between the sparge pipes into a receiver unit fitted below the grate assembly. At least some of the sparge pipes are provided with a cool medium circulation, wherein at least a part of the cool medium circulation is placed in the sparge pipes at the upper edges thereof, to extend so that it provides a limit to the edge of the aperture system in the upper part of the sparge pipe in the longitudinal direction of the sparge pipe. Devices for supplying fluidizing air comprise a tubular supply channel that is directed from the upper surface of the sparge pipe. The supply channel is provided with air nozzle apertures at its upper part.

Abstract: Method of reducing corrosion in a power boiler of a pulp mill using biofuel and suspended matter obtained from the waste water treatment of the mill. In the method flue gases obtained from a waste heat boiler are fed into the power boiler, causing the sulfur dioxide contained in them to react with the alkali chlorides in the boiler and the chlorine to form hydrogen chloride.

Abstract: A grate assembly for a fluidized bed boiler comprises a number of parallel sparge pipes or the like extending side-by-side in a substantially horizontal plane and provided with elements for supplying fluidizing air from within the sparge pipes or the like into a combustion chamber located above the grate assembly. The discharge of some of the fluidized bed materials is effected through an aperture system formed between the adjacent sparge pipes into a receiver unit fitted below the grate assembly. The sparge pipes are provided with a cooling medium circulation by means of a duct assembly.

Abstract: A combustion unit for a circulation process comprises a reactor chamber and at least one particle separator placed inside the reactor chamber in the upper part thereof. At least the first outer casing of the particle separator is arranged to form a heat transfer surface. A flue gas inlet into the first outer casing is arranged to extend for the entire circumference of the casing.