Patent GB-893725-A (GB)
Title: Forced through-flow steam generators
IPC: F22B29/08
Filed: 1959-03-09
Abstract: 893,725. Regulating combustion. SULZER FRERES S.A. March 9, 1959 [March 10, 1958], No. 8085/59. Class 51 (1). [Also in Groups XIII and XXIX] In a forced-flow once-through high capacity steam generator which may work at subcritical, critical or supercritical pressure, the spatial distribution of the firing is adjustable so that each of two tube systems I, II absorbs a quantity of heat corresponding to the quantity of working medium flowing through it. As shown in Fig. 1, the tube system 1, comprising a regulating valve 14, an economizer 15, a vaporizer 16, and preliminary and final superheaters 17, 18 is fed by a pump 13 with preheated water branched from a feed line 12, the valve 14 being controlled by a motor 22 responsive to a temperature-sensing element 21 located between the superheaters 17, 18. The temperature of the steam emerging from the final superheater 18 is regulated by a waterinjection valve 27 which is controlled by a motor 25 supplied with signals through a line 24 leading to a temperature-sensitive element 23 on the output side of the superheater 18. The steam is taken to a turbine 19 which drives a generator 20 and steam from the tube system II, the construction of which corresponds with that of the system I, is taken to a turbine 19a and an associated generator 20a. A burner 28 is tiltable toward one tube system or the other by means of a motor 30 which is linked at 29 to the burner 28 and is controlled by signals received through a line 36 from a regulating member 33 connected by members 32, 32a to the vertically slidable sleeves of speed governors 31, 31a of the turbines 19, 19a respectively. The regulating member 33 comprises a linkage mechanism, Fig. 2, which, in accordance with the difference between the speed deviations of the turbines 19, 19a, actuates the motor 30 to tilt the burner toward the tube system of the slower turbine. The governors 31, 31a are also connected by lines 34, 34a respectively to another linkage regulating member 35 associated with the regulating member 33 and which, in accordance with the algebraic sum of the speed deviations of the turbines 19, 19a increases or decreases the fuel supply through a valve 39 to the burner 28 in accordance respectively with a corresponding overall decrease or increase in the speed of the two turbines. In the case of different dimensioning of the two tube systems a corresponding division of feedwater is effected and the leverage ratios of the linkages of the regulating members 33, 35 are correspondingly adjusted. Where furnaces have a plurality of tiltable burners the latter are movable toward, or away from, their respective tube systems. Alternatively in a fixed burner system, Fig. 4, the fuel supplied to auxiliary burners 82, 83 and 84, 85 associated with the two tube systems is controlled by motor-operated valves 86, 87 and 88, 89 respectively. Interconnected, pivotallymounted wiper arms 96, 97, Fig. 5, movable by a motor 101, corresponding to the motor 38, Fig. 1, contact resistances 94, 95 which are connected between the poles of a source of direct current and are connected to lines 91 and 93 which, with lines 90 and 92 connected respectively to the central parts of the resistances 94, 95, supply current in parallel to the motors of the valves 86, 87 and 88, 89. Restriction of one pair of valves 86, 87 or 88, 89 correspondingly opens the other pair and vice versa. In the generator, Fig. 6, a pressure difference sensing unit 124, which is connected to restrictors 119, 120 in feed-water branch lines 117, 118 respectively, regulates a motor 126 which controls a valve 127 in the branch line 118 and maintains uniform division of feedwater between the two tube systems III, IV. A valve 128 in the branch line 117 may be controlled according to the steam temperature after the vaporizer 112. The motor 148 of a tiltable burner 134 is controlled by a pressure difference sensing device 142 which is responsive to pressures downstream of restrictors 140, 140a in water injection lines 129, 129a respectively. The fuel supply to the burner 134, through a valve 136 in a line 135 is controllable in the manner described with respect to Fig. 2. In a steam generator for operation at subcritical pressure, Fig. 7, the quantities of heat carried off with the line steam and with the water from the water separators of the two tube systems are added respectively in units 177, 177a which lead through lines 181, 181a to a comparator 182 which delivers, through a line 183, a signal to the adjusting motor 184 of a tiltable burner 185 dependent upon the difference between the sums formed in the addition units 177, 177a. The conditions are made such that the burner is tilted toward the tube system from which a smaller quantity of heat is carried off. The comparator 186 may be influenced by a signal in a line 187 dependent on the load as sensed by a restrictor 186 in a common steam output line 166. The embodiments of the invention can be applied to steam generators in which more than two tube systems are associated with a common furnace. Also, portions of individual heat-exchange surfaces of the two tube systems may be combined with one another. In the ease of operation at supercritical pressure the vaporizers of course should be spoken of as conversion zones. The spatial distribution of the firing could be effected, e.g. by varying the position of the flame of a stationary burner or by modifying the direction of the supply of primary or secondary air, or both.