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.

84 THE STEAM INJECTOR. heat energy leaves the injector in three forms. In the first place, a portion, of same is converted into work (1 B.T.U. being the equivalent of 778 foot-pounds), and pro- vides the propulsive force for imparting velocity to the delivery jet; a second, and the greatest portion, serves to give the delivery jet a high temperature; and a thi id portion radiiates from the injector casing. We will consider an injector working under the following ■conditions:— St^am pressure, Ibs. per sq. inch absolute. Feed-water temperature. Height of lift. Pressure in injector, Ibs. per sq. inch absolute. Ratio of water to steam in Ibs. Delivery temperature. Delivery 1 pressure, Ibs. per sq. inch absolute. 95 Deg. F. 97 Ft. 2 5 13 to 1 Deg. F. 175 115 We can readily asoertain the quantity of heat energy requirød to produce a delivery jet of a certain pres&ure if the weight of the jet and also its temperature are known. In the present case the weight of unit mass of the jet may be taken as 1411®. (1 Ib. steam and 13 Ibs. water), the delivery pressuæ is 110 Ibs. above the pressure within the injector (which is 5 Ibs. per square inch absolute), and the- fluid head equivalent of 1 Ib. pres-sur© when tlie fluid temperature is 175 <leg. Fah. is 2'375 ft. Heat energy required to produce the delivery jet Mass in Ibs. * velocity2 Joule’s equivalent 2 g W = — x (Head equivalent of pressure of jet, ' in feet) 14 = WX (11° x 2‘375) •' = 4'7 B.T. units approximately.