| 摘要 |
The invention relates to a grate assembly for a fluidized bed boiler, a number of parallel sparge pipes extending substantially in horizontal direction and being provided with fluidizing air supply conduits for supplying fluidizing air from within the sparge pipes into a combustion chamber (T) located above the grate assembly. Coarse combustion material is discharged through an aperture system between the sparge pipes and into a receiver unit fitted below the grate assembly. At least some of the sparge pipes are provided with a cooling medium circulation system, wherein at least one coolant conduit of the cooling medium circulation system is placed within a surface of the sparge pipes at the upper edges thereof, to extend in a manner that it provides a limit to the edge of the aperture system in the upper part of the sparge pipe and in longitudinal direction of the sparge pipe. The fluidizing air supply conduits comprise a tubular air supply conduit that is directed upwardly away from the upper surface of the sparge pipe. The air supply conduit is provided with air nozzle apertures, in particular, at its upper end. The air supply conduit for at least some of the fluidizing air supply conduits is fitted in vertical direction to extend vertically above the coolant conduit of the cooling medium circulation system. This provides for an effective fluidizing air supply at the upper end of the aperture without the use of excessive air flow and pressure, thereby controlling operating cost.
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