GB433807A - An improved method of and means for regulating temperature of steam delivered by a steam superheating installation - Google Patents

Abstract

433,807. Steam superheaters. SUPERHEATER CO., Ltd., and WOOD, J. E., Bush House, Aldwych, London. April 19, 1934, Nos. 11866 and 35460. [Class 123 (iii)] A desuperheater 1 is so disposed in relation to the water level in the boiler drum 3 to which it is connected by a pipe 2 that the water in the desuperheater is constantly subjected to boiler pressure tending to feed it into the desuperheater against the pressure of steam from a convection type superheater, varying with the boiler load, acting on the water surface so that the water level in the desuperheater and the consequent desuperheating effect varies with alterations in the pressure drop in the superheater, the final steam temperature thus remaining constant irrespective of load variations. In the form shown a primary superheater 6 is connected to the top of the desuperheater, and the desuperheated steam with steam generated in the desuperheater passes to a secondary superheater 10. A choke or valve 11 in pipe 2 obviates the necessity for an inconveniently high desuperheater, its value being determined according to the characteristics of the particular boiler. In a modification compensation is effected for the influence of ash on the superheater elements or boiler tubes or of other factors. One such arrangement provides a bifurcated steam passage to the desuperheater one leg constituting a fixed and the other having a variable resistance manually or thermostatically controlled so as to superimpose an additional effect on the desuperheater water level, or a valved pipe may byepass the superheater. A branch pipe from the boiler feed line may supply the desuperheater and a choke in this pipe is supplemented by a choke in the pipe length between the branch and the boiler to compensate for superheat variations accompanying changes in rate of water feeding. The desuperheater may be byepassed by a valved pipe under manual or thermostatic control or both. Another modification provides means for avoiding a stagnant body of water in the desuperheater and comprises a number of pipes communicating with the desuperheater at various heights and drawing water therefrom by the action of a Venturi tube in the feed pipe between the desuperheater supply pipe and the boiler.