GB903576A - Method and apparatus for the determination of steam moisture - Google Patents

Abstract

903,576. Determining the moisture content of steam. VYZKUMNY USTAV ENERGETICKY PRAHA. July 30, 1960, No. 26622/60. Class 97 (3). Steam passing through a conduit is induced by means of an injector to enter a dete ctor 1, Fig. 2, or controlled in its entry by means of a valve, not shown, at the exit 9 of the detector 1, according as the pressure of the steam is less than or greater than atmospheric, the detector having means 2a, 6a for measuring the initial pressure, P0, and temperature t0, (not marked) a heater 8 for bringing the moist steam to a stage of superheat, means 2b, 6b for measuring the pressure P1, and temperature t1, at this lower superheat, a further heater 8 for raising the steam to a stage of higher superheat and means 2c, 6c for measuring the pressure P2 and temperature t2 at this higher superheat. The ratio Q 1 /Q 2 of the heat inputs to the two heaters 8 is measured by an instrument 12 and it is shown in the Speci- fication that #i 1 =Q 1 /Q 2 #i 2 , where #i 1 and #i 2 are the differences in enthalpy from moist steam to the lower degree of superheat, and from the latter to the higher degree of superheat, respectively. From the graph, Fig. 1, of enthalpy i against entropy s, the position C of higher degree of superheat is readily found from a knowledge of P2, t2. Similarly position B corresponding to lower degree of superheat, P1, t1 can be determined and thus the value of #i 2 read off. On calculating the value of #i 1 and knowing the value of P0, the position A is determined from which the moisture content X0 can be read off. The pressure of the steam outside of the detector may be measured by means 4 to ensure that it is the same as that P0 inside. The apparatus may be used for controlling the moisture content of steam.