Kvaerner Pulping Oy

Enviropower Oy

Martti Pohja

Jouni Kinni

Kari Haverinen

Kari R As Anen

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. The supply channel for at least some of the devices for supplying fluidizing air is fitted in vertical direction to extend on top of a part of the cool medium circulation in a vertical direction.

Grate assembly for a fluidized bed boiler

The invention relates to a method for cooling and cleaning gases containing tar-like or other impurities, and to a reactor. In the method, process gas is first fed into a hot fluidized bed (4), where the tar-like impurities contained in it crack into smaller fractions, whereafter the process gas is passed onward, the fluidized bed material entrained in the process gas is separated from the process gas and returned through the cooler (8) into the fluidized bed and into the process gas stream, whereby the process gas cools under the influence of the cooled fluidized bed material. The reactor comprises a cooler (8) above the fluidized bed (4) and an annular conduit (7) outside the cooler (8), through which conduit the process gas flows into the upper portion of the reactor after the fluidized bed (4). It further comprises a fluidized grate (11) below the cooler (8), to which grate the cooled fluidized bed material from the cooler (8) drops, and from where the fluidized bed material is returned into the fluidized bed (4) and into the process gas stream by feeding the process gas to be treated into it as fluidizing gas.

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Tampere, Finland

Martti Pohja