Regulation of a forced flow, once-through steam generator operating with the working medium at super-critical pressures

摘要

859,189. Feedwater regulation of critical-pressure boilers. SULZER FRERES S.A. March 12, 1959 [March 13, 1958], No. 8662/59. Class 123(2) In a method of regulating a super-critical, forced-flow steam generator, the feed quantity of the working medium of which is adjusted according to the alteration in the intensity of firing, pre-correction is effected by a signal which represents the quantity of working medium flowing per unit of time and is derived from a liquidphase region of the generator where the gradients of the isobars p, shown at intervals of 20 atmospheres absolute from 220- 400 in the Figure, is small, i.e. between the values i=400-600 total heat units expressed in K. cal. per Kg. Post-correction is accomplished by a signal representing a temperature of the working medium at a steam-phase region of the tube system where isogradients JSP1/SP, each passing through points on the isobars where the incremental rate of change of the temperature t for a change of 100 heat units is constant, lie between the values of J'= 30-100‹C. per 100 units of heat. The temperature and feed quantity signals are preferably derived from an area of the tube system located as near as practicable to an irrational phase-changing region Pk occurring at the points of inflection of the isobars. A preferable area is near the point of intersecting S on the drawing, of the ordinate I=600 heat units and the isogradient JSP1/SP=30‹C. per 100 heat units. When it is desired to free, as far as possible, the temperature signal from the influence of the quantity signal it is most favourable to dispose the temperature derivation point between the isogradient J=60-70‹C. per 100 heat units.