Abstract
The paper describes the chief troubles encountered in operating high-pressure La Mont forced circulation boilers with a difficult feed water consisting of 80 per cent chemically treated make-up. Attention is drawn to the thermodynamic and financial advantages gained by the use of the higher pressure system.
The reasons for the choice of the La Mont boiler are given and also a summary of information obtained on the Continent in 1939 relating to feed water treatment with La Mont boilers working under nearly similar conditions of pressure and feed water. The initial feed water treatment and after-conditioning, together with details of the feed water treatment plant for the boilers actually installed, are described. The early troubles with feed water treatment and their effect on the availability of the boiler are dealt with in detail and the precautions found to be necessary to avoid accumulation of sludge in the headers and the formation of “Analcite” scale in the generating tubes are also described. Information is given of the troubles with secondary combustion as a result of insufficient turbulence in the combustion chamber and the fouling of the air heaters and the remedies employed. The general design of the boiler and power plant and of all auxiliary plant are described, and the reduction in power costs achieved, in spite of war time increases in the cost of coal and labour, are enumerated.
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