Abstract
That it is possible to effect material savings in power plants is evident, according to the author, when it is considered that fifty or even a hundred per cent more fuel is burned in some cases than would be required by plants of the best economy. It does not follow, however, that it would pay to replace all plants of low efficiency by those having a higher efficiency. There are many factors which must be taken into consideration before deciding that a new investment is warranted, and each case must be considered individually in order to determine whether or not it will pay to replace an existing plant by one of more economical type, or to add apparatus to increase the efficiency.
The present paper accordingly deals with such questions as when it will pay to use economizers in a new plant; the most economical rating at which to operate a boiler; limitations imposed on efficiency by inability of furnace brickwork to withstand temperatures available with many classes of fuel; furnace volume and length of flame travel; where air heaters are of a special advantage; importance of employing properly trained men for boiler operation; information afforded by flue-gas analyses, etc., etc.
The author points out in closing that furnace and boiler design must be coördinated in order to secure the best results. It is impossible to separate the boiler efficiency from the efficiency of the stoker and furnace in such a way that the value obtained for the former will depend solely on the construction of the boiler and not be influenced through the construction of the stoker and furnace. The stoker and furnace efficiency is influenced by the delayed or secondary combustion between the boiler tubes and this cannot be included in any analysis, neither can the loss due to excess air be correctly divided between the boiler and furnace.