April 4, F. SALZMANN 2,345,950‘ THERMAL POWER PLANT Filed July 19, 1943 LOW PEESSLAQE EESEE l/O/B ‘ ? l/VVE/YTG/a’ F sngmw. @r am, a 2,345,950 _ Patented Apr. 4, 1944 UNITED. STATES PATENT, OFFICE THERMAL POWER PLANT . Fritz Salzmann, Zurich, Switzerland, assignor to Aktiengesellschaft fuer Technische Studien, ‘Zurich, Switzerland, a corporation of Switzer land Application July 19, 1943, Serial No. 495,345 In Switzerland May 9, 1942 I 3 Claims. This invention relates to thermal power plants iniwhich at least the greater part of a gaseous working medium, preferably air, describes a closed circuit at a pressure above atmospheric, the working medium which is heated by a supply of heat from an external source being expanded in at least one turbine giving up its output ex— (Cl. 60-—59) part-of the circuit situated between ‘turbine dis~ charge and compressor inlet. _ ' The present invention depends on this fact-in ' that it makes use of the same to maintain the speed governing of the plant as stable as pos sible, i. e. to ensure that ?uctuations of speed which set in owing to a change in output are ternally and thereafter being again brought to caused to die ‘out as quickly as possible. a higher pressure in at least one compressor. It A known measure for improving stability of has already been proposed to provide in such 10 ‘regulation is to utilize the action brought about power plants means controlled automatically in by the regulating operation for temporarily re dependency on the load on the plant and which, storing the control gear to a greater extent than when a change in load takes place, permit work the condition prevailing after completion of the ing medium being supplied to or ‘withdrawn regulating operation would require. In this con from the circuit at a point where a high pressure 15 nection one speaks of a so called “accelerated” prevails. , restoring action. According to the present in Changes in load can in such plants also be vention such an “acceleration” of the restoring brought about by altering the absolute pressure movement is brought about in that the restoring in the circuit or the weight of the working .me movement of ‘the automatically governed means dium ?owing in the circuit. Any change in the 20 for regulating the supply and withdrawal of pressure condition then ‘involves at every point working medium to and from the circuit is of the circuit, compared with the originally pre eiiected in dependency on the variation of the vailing condition, a change in pressure of the highest pressure prevailing within the circuit same ratio. ‘The pressure at every point of the and under the counter action caused by the circuit is always substantially proportional to variation of the lowest pressure occurringiwithin the output produced by the plant. the circuit. A ?xed relationship between output and speed A preferred embodiment of the invention is of the plant can be ensured, as is already known, illustrated by way of example and in a simpli?ed if the means in?uenced by the speed and serving mode of representation on the accompanying for supplying and withdrawing working medium 30 drawing. to or from the circuit are controlled by the pres sure prevailing at a given point of the circuit. Inv the thermal power plant illustrated the working medium used in carrying out the cycle In this way rapid action of the regulating oper ?ows, in a manner known per se, through a ation can be brought about if the supply and compressor l, a heat exchanger 2, a heater 3, 35 withdrawal of working medium are effected at a a turbine 41, then again through the heat ex- ‘ point ofthe circuit where a high pressure pre changer 2, and afterwards through a cooler ii, whence it passes again to the compressor I. As If this is the case, then, for example when consumer of useful output a generator 6, driven - working medium is supplied to the circuit, the by turbine 4, is provided, a centrifugal governor 40 pressure head in the plant is immediately in ‘I beingoperatively connected to the shaft of the creased so that the output of the turbine is, as latter. When changes in speed occur this cen required, quickly increased. The ratio between trifugal governor 1 initiates movements ending vails. . ' - maximum and minimum pressure in the plant is > in a supply of working medium to the circuit or consequently temporarily increased and only 45 a withdrawal of working medium from'said cir gradually returns to the normal value when the > cuit. To this end the governor ‘I is operatively plant is left to itself, 1.. e. after the supply of - working medium has been terminated. connected by a beam 8, a rod 9, and a lever l0 vto a slide valve l2 linked to the latter at point Consequently when supplying working medium II. This valve l2 controls the supply of a pres-, to the circuit the pressure‘ before the turbine‘will 60 sure medium to an auxiliary servomotor IS, the at first change to'a‘ greater extentfthan the‘back movements of which operate a .slide valve ll pressure ofthe ‘turbine,- sincefthe ;1ea¢reoes.net , I which, when ‘being displaced from its center posi commence rising until a certain- surplus-of work- 1 " tion, in: medium, compared with the volumedealt with by the compressor, has, gained access to that ' , either allows working medium to ?ow'from a high pressure storage reservoir l5 into the cir cuit at point H5, or permits working medium 2 2,845,950 2| in a clockwise direction. The upward move-_ ment of rod 9 brought about by the de?ection of the centrifugal governor ‘I is therefore again restored. This action brought about by the drop in pressure pn is again mitigated by the subse-_ quent, retarded lowering of the pressure 1m in the low pressure part of the circuit. withdrawn from the circuit at said point l6 to pass into a low pressure storage reservoir II. The point It at which working medium is sup plied to or withdrawn from the circuit and which lies between the discharge end of compressor .| and the inlet end of turbine 4 is consequently disposed at a point of the circuit where the work ing medium has a high pressure (1m). To the'left hand end l8 of beam 8 a’ rod I9 In order to ensure on the completion of a regu lating operation in a thermal power plant of the 24 are further articulated, the lower surfaces of which are subjected to the pressures pn'and'jm - smaller speed, the surfaces of pistons 23 and 24, on which the pressures 1m and m respectively act, must be .so dimensioned'and furthermore the lengths or the lever arms of beam 2| between is articulated, which is connected at its other end 10 kind herein described, such a coordination be tween speed and load that a smaller load corre 20 to a beam 2| adapted to oscillate about a sponds to a higher speed and a larger load to a point 22. To the beam 2| two pistons 23 and respectively, the pressures pa being transmitted from a point 25 of the circuit where a high pressure prevails and the pressure pp from point 26 of said circuit where a low pressure exists. At the joint 20 the beam 2| is further subject to the action of a spring 21. The regulating arrangement of the described . thermal power plant works in the following man- ' ner: . If for example the power consumption of the generator 6 increases, the result is a decrease in fulcrum 22 and the point where the rods of pis tons 23 and 24 are articulated to said beam 2|, must be so chosen that, when the pressures pa and 1m vary in the same ratio, the in?uence of the change in pa as compared with the in?uence of the change in m is always preponderant. When this condition is fulfilled, then in a state of equilibrium, that is to say when the slide valves 12‘ and H are in their midposition, a small load, speed of the set |, 4, 6, so that the lever 8 is . ' i. e. a low pressure level, is coordinated to a higher ' speed and vice versa. If the effects of the pres turned in a clockwise direction about the point l8, which for the time being is still stationary. The result of this is that the slide valve |2 moves downwards whilst the piston of the‘ auxiliary 30 servomotor l3 moves upwards and together there with also valve l4, which now allows working medium to ?ow from the high pressure storage. reservoir l5 to the point l6 of the circuit. The. sures pa and pi: on the restoring movement of the regulating mechanism just balance one another, owing to changes in the same ratio taking place, an isodromic regulation results.» ' 1 Since in a thermal power plant according to the present invention a‘ change in the pressure Du'occurs with a. certain retardation with regard ?rst result hereof is that the pressure pa in this 35 to the change in the pressure he, a temporary restoring movement is brought about, which ex part of the circuit increases. This rise in pres ' cceds the restoring movement, actually required sure is transmitted through the pipe branching for the ?nal condition, with the result that the off from the circuit at point 25 to the lower sur stability of the regulation is, as it is well known, face of piston 23 and causes the beam 2| to turn in a counter-clockwise sense and against the ac 40 favourably in?uenced. The intentionally exces sive restoring movement referred to is again com tion of spring 21. The joint I8 is now raised pro pensated by properties peculiar to the plant itself portionately to said rise in pressure, so that rod (the above mentioned retarding action), so thatv 9 is also raised and the regulating mechanism the same characteristics of the regulating ar therefore restored, with the result that the supply of working medium to the circuit at point I6 45 rangement suited to the plant always result, and this quite independently from any changes in the is again reduced. viscosity of a throttled oil current. - As soon as a corresponding portion of the sup The operative characteristics of the preferred plied working medium passes, after having given embodiment which are above stated in consider up energy in turbine 4, into the low pressure part able detail can be summarized in the following of the circuit (which part extends up to the inlet terms. With the right hand end of the lever II end of the compressor D, the pressure 1m in this part rises. This rise in pressure is transmitted , in the position shown in the drawing valve H can lap only. when valve l4 laps. If the right to piston 24 so that the latter tends to prevent _ the turning movement of beam 2| brought'about. hand end of lever Ill be raised or lowered the valve by piston 23 as a'result of the increase of pres?“ 55 l2 will vmove from its lap position and then be restored to lap position with the valve l4 open sure PH. Therestoring movement of the automatically ‘ actuated mechanism regulating the supply of _ working medium to the circuit therefore takes place in dependency on the variation of the high est pressure pn, occurring in the circuit at any time, and under the counter-action of the varia tion of the lowest pressure 1m existlng'within the circuit. ‘ a - a in one direction or the other so as to connect either the low pressure reservoir or the high pres sure reservoir with the point IS in the circuit. , The resulting changes of pressure in the circuit react ?rst through the piston 23 and then through the piston 24.‘ The ?rst reaction is aneutralizing action with respect to the‘change produced by the governor. The second partly eliminates that .If on the other hand the power consumption 65 neutralizing effect. When the system is in equi librium, that is when the load and the output are of the generator Gdecreases, the result is an in balanced, the control system will assume the posi crease in speed of the set I, 4, 6, so that opposite tion shown in the drawing. The high pressure movements of the di?erent parts of the regulat piston 23 'is the dominant‘piston as explained ing mechanism to those described above take place. The slide valve I4 is now forced down ~70 and re-zeroes. the system so that the plant runs at slightly different speeds for different loads. wards thus permitting working medium with What is claimed is: drawn from the circuit at point IE to flow into V ,1. Means for the regulation of the output of the low pressure storage reservoir IT. The re “thermal power‘ plants, in which at least ‘the sult of this is a drop in the pressure 1m so that greater partv of a gaseous working medium de spring 21 can‘ expand, thereby turning, the lever 3 ‘ 2,345,950 scribes a circuit, is heated by a supply of heat from an external source, then expanded whilst delivering power and afterwards again brought to a higher pressure, comprising in combination means responsive to load changes and serving ' according to the direction of load change to with draw or supply working medium from and to that portion of the circuit at which the pressure is h'gh, whereby a pressure change is ?rst induced in the high pressure part of the circuit and later becomes eiTective in the low pressure part of the circuit; and means subject to the pressure dif ferential between the said two parts of the circuit and serving in response to the successive pressure 'changes produced therein by action of the load responsive means to exercise a neutralizing eifect on the action of said load responsive means, said neutralizing eifect being ?rst intense and then diminishing. , v taking place, permit of working medium being withdrawn from or supplied to the circuit, and means for imparting to said automatically con trolled means a restoring movement in depend ency on the change in the highest pressure oc curring in the circuit and under the counter ac tion oi.’ the change in the lowest pressure existing within the circuit. i 3. Thermal power plant, in which at least the greater part of a gaseous working medium de scribes a closed circuit, comprising a heater in which said working medium is heated by a sup ply of heat from an external source, at least one turbine in which the heated portion of the work ing medium is expanded, at least one compressor in which the expanded portion of the working medium is again brought to a higher pressure, means controlled automatically in dependency on the load on the plant, which, on a change in load 2.» Thermal power plant, in which at least the 20 taking place, permit of working medium being greater part of a gaseous working medium de withdrawn from or supplied to the circuit at a scribes a' closed circuit, comprising a heater in point where a high pressure prevails, and means which said working medium is heated by a sup for imparting to‘ said automatically controlled ply of heat from an external source, at least one means a restoring movement in dependency ‘on engine in which the heated portion 01' the work 25 the change in the highest pressure occurring in ing medium is expanded, at least onecompressor , the circuit and under the counter action of the in which the expanded, portion oi! the working change in the lowest pressure existing within the medium is again brought to a higher pressure, circuit. means controlled automatically in dependency on the load on the plant, which, on a change in load 80 mrrz SALZMANN.
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