Patent GB-896194-A (GB)
Title: Steam power plants
IPC: F01K3/04
Filed: 1959-12-22
Abstract: 896,194. Power-generating systems. MARGUERRE, F. Dec. 22, 1959 [Dec. 22, 1958; Feb. 4, 1959; May 19, 1959], No. 43596/59. Class 122 (3). [Also in Group XIII] In a steam power plant, having means for increasing output, hot feed-water which, during low-load periods is stored in a reservoir 1, is dischargeable either to a boiler 25 for increasing the steam supply to a main turbine 2 by closing, or partially closing, a valve 9 in a preheater circuit 4-7 and maintaining a valve 19 in an additional outlet from the reservoir closed or, during short high-load peaks, by opening the valve 19 so that hot water from the reservoir can flow successively through liquid-level-controlled expanders 14-12 the nascent steam from which is led to the corresponding pressure stages of an auxiliary turbine 3. Water from the last expansion stage 12 and from a condenser 29 is returned by pumps 23, 18 to the base of the reservoir 1 the pump 18 acting through a valve 15. During normal working, with the reservoir inoperative and neither fully charged nor empty, a valve 9 in the preheater circuit is opened by an amount which ensures that the quantity of water delivered by a preceding pump 8 corresponds to that supplied by a pump 10 forcing condensate from a condenser 11 for the main turbine 2. When the reservoir 1 is to be charged it is filled with cold water and the valve 9 is opened further by an amount corresponding to the desired charging rate so that additional reservoir water is circulated by the pump 8 through the preheaters 4-7. When the generator 42 coupled to the auxiliary turbine 3 cuts out quick-action elements 24 interrupt the supply of steam to the turbine 3, the valve 19 also being closed and expander valves 20-22 opened for water to drain to the condenser 29. A low-pressure part of the turbine 3 can be shut off by closing a valve 28 and when the main turbine 2 drops out steam from the boiler 25 can be fed through a valve 27 to the turbine 3. In an alternative arrangement the expanders are replaced by evaporators, the condensate from the turbine 3 in this case being pumped back through valve-controlled lines to the various evaporators. The valve 9 may be omitted, regulation being carried out by controlling the speed of the pump 8. The feed-water for the evaporators may be preheated in between the evaporator stages. In a modification of the embodiment shown in Fig. 1 steam from the expander 14 is mixed with exhaust steam from the main turbine steam from the expander 13, or from expanders 13, 14, being superheated, e.g. by the mixed steam or by fresh steam from the boiler. Low-grade heat is also obtained by passing the water from the expander 12 through a heat-exchanger arranged in the circuit of an intermediate hot-water reservoir connected to a low-grade heat supply point in parallel with a main heat supply comprising heat extraction preheaters connected across the preheaters 4, 5. The heat exchanger and preheaters may be omitted in which case water from the pump 18 and steam from the preheaters 4, 5 may be fed directly into the top of the intermediate reservoir. When the valve 9 is fully closed so that the preheaters are inoperative during discharge of the reservoir water from the latter not only passes into the boiler but also into the preheaters 7-4 which act as evaporators passing steam into the main turbine stages. In the arrangement shown in Fig. 4 upon continued discharge from the reservoir 1 the pump 106 is operated to circulate hot feed-water in the opposite direction through a relief valve 114 to the preheaters 7-5. Simultaneously control-valves 113, 109 are opened and closed respectively and valves 110-112 in the lines interconnecting the preheaters being adjusted so that all of the water pipes are flooded. The preheaters, now acting as evaporators, supply steam to the turbine. The regenerative system may be composed of injection elements which, with suitable changeover means, are used as injection evaporators. In addition, the arrangement shown in Fig. 1 may be provided with a single pump which is associated with two three-way valves for continuous changing from one operating condition to another.