| 摘要 |
1285084 Operating shaft furnaces WESTDEUTSCHE KALK UND PORTLANDZEMENT WERKE AG 24 Nov 1969 [27 Nov 1968] 57441/69 Heading C1A In the operation of a shaft furnace for calcining carbonate-containing ores, which is heated by fuel oil injected at the periphery and in the centre by solid fuel, the level of the combustion zone in the centre is maintained at a constant level relative to the oil burners by supplying a fuel with a higher ignition temperature when it is necessary to lower the level of the combustion zone and one with a lower ignition temperature when it is necessary to raise the level of the zone. Usually the inner combustion zone and the outer (oil fired) combustion zone are maintained at the same level in order to produce even heating of the charge. In furnaces of large diameter different solid fuels may be supplied in annular zones, preferably with the ignition points of the fuels decreasing towards the centre so as to give an upright conical combustion zone. The ignition point(s) of the solid fuel(s) should preferably be such that the waste gas leaving the top of the furnace is above its dew point. |
