The Steam Injector
A theoretical and practical treatise on the design and operation of injectors and on the flow of fluids through and the design of nozzles.

EXHAUST STEAM INJECTORS. 103 CHAPTER IX. Exhaust Steam Injectors. Even before the advent of tlæ “ Giffard ” injector in 1858 engineers had endeavoured to make practical use of the heat energy represented by the exhaust or waste steani from non-condensing steam engines. Such heat energy might be utilised as a hea-ting medium, or, by conversion into work, as a propulsive force, or botli as a heating medium and a propulsive force. Exhaust or waste steam also represents a great amount of water which. might be recovered. The chief proposals of the early engineers had, however, for their object not the utilisation of the exhaust steam as a propulsive force for boiler feed purposes, but the ©mployment of such steam as a feed-water heating medium. The prirfciples upon which the construction of exhaust injectors is based were first enunciated with a degree of accuracy in 1876. The folio wing gives a summaiy thereof:— “ It is known that when steani is condensed a vacuum is created, the degree of which is dependent upon the tem- perature of the water of condensation; and when this temperature is low, and the vacuum therefore good, it is found that the velocity of steam of different pressures flow- ing into it does not differ in anything like the proportion ■)f the pressures. “ The exhaust injector differs from ordinary injectors in having the final cross-sectional area of the steani-inlet passage or nozzle much larger in proportion to that of the water passage and to that of the 1 tliroat ’ or,smallest section of the delivery nozzle than is the practice in ordinary injectors, so as to provide for the larger volume of the exhaust steam in order to pass about the same weight of exhaust as would have been used of ‘ live ’ or boiler steam; for it will be understood that, though the velocity of the particles of exhaust steam on leaving the