ABSTRACT
The development of the turbo-generator was coming to a standstill. The boiler surface relative to that of the economizers and superheaters has been diminished and the present tendency is in the direction of the high-head boiler, where the vertical distance between the drum and the convection surface is longer than hitherto and this head therefore helps to overcome circulation defects. It is a high-head controlled gas flow boiler fired by low volatile pulverized fuel, to deal with which it has a Bailey hopper bottom furnace, i.e. with water-cooled walls. It will be remarked that these boiler plants comprise in themselves: pulverizers, air preheaters, superheaters and feed-water heaters. The pressure combustion boiler arose out of research carried out by Brown-Boveri & Co., of Baden, Switzerland, on super-charging of Diesel engines and the construction of the Holzwarth gas turbine.
