| 摘要 |
The aim of the invention is the advantageous change-over of oil-fired or gas-fired water-tube boilers to grate firings. In this connection, after the conversion of the boilers, their nominal steam generating capacity is to be achieved fully again. Furthermore, the existing contact heating surfaces of the boiler are also to be taken over extensively unchanged, but the maximum flue gas speed in them is to be reduced. Additional contact heating surfaces are to be installed in order to achieve adequate cooling of the flue gases at the lower combustion temperatures of the coal firing. These aims are achieved by the arrangement of ancillary blocks which are connected on the flue-gas side parallel to the existing contact heating surfaces of the boiler. On the side of the cooling media (feed water, steam) also, the ancillary heating surfaces are connected parallel in terms of flow to the existing contact heating surfaces of the boiler. In order to reduce the size of the grate necessary, combustion air is blown onto the grate via a system of cooled secondary-air ducts, as a result of which an intensification of the combustion process is achieved. <IMAGE>
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