| Abstrakt: |
In the first section of this paper a method has been developed for converting well-known types of furnace heat-absorbing surfaces into an equivalent effective radiant heating surface. It concerns the evaluation of this effective radiant heating surface as controlled by (1) various spacings of waterwall tubes, (2) various kinds of blocks on the waterwall tubes, (3) various amounts of slag on the waterwall tubes or blocks, and (4) the emissivity of the waterwall surface exposed to the flame. The second section deals with the fraction of heat supplied to the furnace that is given up by the gases in the furnace which is solved most simply and practically by the use of the Stefan-Boltzman radiation law. Results computed in this manner have been compared with results reported in a paper entitled, “An Experimental Investigation of Heat Absorption in Boiler Furnaces”. It is found that for large pulverized coal, and oil-fired and gas-fired furnaces, the assumption of an effective furnace emissivity of unity leads to results which are in substantial agreement with experimental data. For stoker-fired furnaces in general, the effective furnace emissivity appears to be less than unity. |
