US2071268A - Elastic fluid power plant - Google Patents

Description

G. B. WARREN .Feb. 16, 1937.

ELASTIC FLUID POWER PLANT Filed April 25, 1955 m x 4 m e r Wmww MW w WB A I 5 n W k Patented Feb. 16, 1937 PATENT o FicE ELASTIC FLUID POWER PLANT Glenn B. Warren, Schenectady, N. Y., assignor to General Electric Company, a corporation of New York Application April 25, 1933, Serial No. 667,812

. 12 Claims.

The present invention relates to elastic fluid power plants in which elastic fluid, for instance, steam or vapor, is produced in an elastic fluid generator and consumed in a consumer. The

,. elastic fluid generator usually comprises a boiler, that is a container or containers such as drums and heating tubes in which liquid is heated and evaporated, means including a preheater for supplying and controlling the supply of make-up or feed fluid to the boiler, a furnace for heating the boiler, and means for supplying and controlling the supply of fuel and air to the furnace. The consumer may comprise an elastic fluid turbine, means for conducting and regulating the flow of elastic fluid to the turbine, and means including a condenser for receiving exhaust fluid from the turbine. The means for supplying and regulating the supply of feed fluid to the boiler and the means for supplying combustible material and air to the furnace may include pumps and a blower driven by auxiliary motors or prime movers such as elastic fluid turbines receiving drive medium from the boiler.

The object of the present invention is to provide an improved arrangement for power plants of the type specified whereby the control and regulation of the various apparatus is accomplished in a simple manner.

For a consideration of what I consider to be novel and my invention, attention is directed to the following description and the claims appended thereto, in connection with the accompanying drawing.

In the drawing, Fig. 1 represents a power plant embodying my invention, and Figs. 2, 3 and 4 show modifications of the control arrangement of a certain part of the power plant.

In Fig. 1 I have shown by way of example a power plant according to my invention adapted O to be usedin aircrafts. The elastic fluid generator comprises a furnace Ill havingawasing H, and means for supplying fuel and air to the furnace. The fuel supply means include a source of fuel, such as a tank l2 containing oil, a conduit l3 connected to the fuel tank I2, a fuel pump i4 and a conduit I5 for conducting the fuel to a burner i6 located within the furnace. The air supply means include a channel or suction conduit Ill and a blower 18 having a discharge conduit connected to the furnace. The pump it is preferably a positive displacement pump. Both the pump l4 and the blower l8 are driven by a common motor or prime mover, in the present instance shown as an auxiliary turbine i9 having a shaft connected to the-pump l4 and the blower l8 by gears 2| and 22 respectively.

In accordance with my invention I proportion the blower I8 including the suction or inlet conduit I! so that for a certain condition an amount 5 of air is supplied to the furnace which is sufiicient to maintain the combustion of the fuel such as oil supplied by the pump M to the furnace. By a certain condition is meant a certain barometric pressure and the drop in pressure in the suction conduit which depends upon the relative velocity of the airplane with respect to the current of air outside the inlet or suction conduit ll. We may assume that the speed of the motor or auxiliary turbine l9 changes in accordance with the demand for elastic fluid output in the elastic fluid generator. The means for accomplishing this will be described later. With this assumption the pump I 4 and the blower l8 serve to supply an amount of fuel and air for 20 maintaining the combustion, which amount under the above mentioned certain condition is sufficient to generate the necessary elastic fluid at varying loads. To obtain the right proportioning between the fuel and air supply at other conditions, I provide in accordance with my invention regulating means for regulating the flow of air in the inlet or suction conduit ill of the blower in response to changes in barometric pressure, changes in the flow of air in the suction conduit i1, and changes in the flow of fuel in the fuel conduit 53. The control arrangement comprises a nozzle 23 in the conduit l3, a nozzle 24 in the conduit ii, flow responsive means 25 and 26 connected .to the nozzles 23 and 24 respectively, a barometric pressure responsive device 2'! and a valve 28 shown as a butterfly valve in the air suction conduit ll. More specifically, the barometric pressure responsive device has a bellows 29 with a lower portion. fixed to a support 30 and a top portion connected to one end of a fulcrumed lever 31 which has its other end connected by means of a spring 32 to a link 33 for moving the valve 28. A spring 34 provided between the bottom and top portions of the bellows and the spring 32 prevent the bellows from collapsing.

With this arrangement a decrease in barometric pressure which occurs whenever the airplane increases its altitude causes expansion of the bellows whereby the lever 3| is turned in clockwise direction and causes downward movement of link 33, to the effect that valve 28 opens and permits an increased Volume of-air to maintain constant the amount or weight of air delivered by the blower. By amount or weight of air is meant the weight of air delivered during a certain period of time. The flow-responsive device comprises a casing having an upper half and a lower half with a diaphragm 36 therebetween. The central portion of the diaphragm is connected to a stem 3'! which has its lower end pivoted to an intermediate point of a lever 38 turning about a fulcrum 39 and being connected to the link 33. The upper casing half communicates with the conduit l3 ahead of the nozzle 23 by means of a pipe 40. The lower casing half communicatees with the conduit l3 behind. the nozzle 23 as regards the direction of flow through the conduit I 3 by means of a pipe 4|. The flow-responsive device 26 is similarly arranged. It comprises a casing 42 with a diaphragm 43 connected to the lever 38 by a stem 44 and pipes 45 and 46 for connecting the lower and upper casing halves respectively to the conduit ll ahead and behind the nozzle 24 respectively as regards the direction of flow through the conduit 11. The flow-responsive device 26 controls the flow of air through the conduit I! in response to changes in pressure drop in conduit 24 caused by changes in the velocity of air through the conduit 24, more specifically by changes of the relative speed between the conduit 24 and the current of air outside the conduit. As stated above, the blower I8 is dimensioned to supply as nearly as possible, under certain conditions, an amount of air sufficient to maintain the proper combustion of the fuel supplied by the pump M. In the case of an airplane power plant it is preferable to make the arrangement so that at normal speed of the airplane, which may be 100 miles per hour, the pump supplies suflicient air to the furnace for maintaining combustion of the fuel supplied by the fuel pump l4. The inlet of conduit l! is locat d in forward direction, so that air is forced into the conduit during flight of the airplane, the amount of air flowing into the conduit increases as the speed of the airplane increases, and vice versa. With this arrangementv an increased speedcauses an increased flow of air through the suction conduit I! which without the provision of special control means would cause an excessive amount of air being supplied to the furnace. With the arrangement of the flow-responsive device 26 an increased flow of air in the conduit ll, due to an increased relative velocity between the conduit and the current of air, causes the diaphragm 43 in casing 42 to be forced upward, owing to the increased pressure drop in the conduit ll, whereby the lever 38 turns in clockwise direction about its fulcrum and effects closing of the valve 28 in the conduit ll. Thus the amount of air conducted through the conduit I1 is maintained constant;

In the arrangement shown in the drawing, the stems 31 and 44 of the flow-responsive devices are arranged in alinement so that no spring means are needed for balancing the pressures acting on the diaphragms 36 and 43. The pressures acting on the two diaphragms balance each other. By properly dimensioning the diaphragms or using different materials for the diaphragms, any desirable characteristic of the-control arrangement is obtained.

If the flow of fuel through the conduit 23 changes, owing, for instance, to the variation of the fuel head in tank 12, the flow-responsive device 25 automatically causes positioning of the valve 28 in terms of change in flow of fuel. If, for example, the flow of fuel increases, the diaphragm 36 of the flow-responsive device is moved downward and causes through the lever 38 and the link 33 opening movement of the valve 28, resulting in an increased flow of air. If the flow of fuel through the conduit 23 decreases, a similar action takes place with the difierent parts moving in opposite direction and resulting in closing of the valve 28.

The two flow-responsive devices 25 and 26 and the barometric pressure-responsive device 21, together with the valve 28, represent in substance means for automatically controlling the supply of air to the furnace in response to changes in fuel supply, changes in relative speed between the conduit I! of the airplane and the current of air,

and in response to changes in barometric pressure.

In Fig. 2 I have shown a modification of this automatic control arrangement. Like parts are designated with like reference characters. The stem 33 of. the valve 28 is biased in this arrangement in upward direction by means of a spring 41, and carries at its upper end a roller 48 bearing against the cam surface of a cam 49 fastened to a shaft 50. Adjacent the cam is a pinion 5| fastened to the shaft 50 and meshing with a rack 52 Connected to the rack 52 is a piston 53 movable in a cylinder 54 and biased towards the left by a spring 55. The cylinder 54 has a lefthand portion connected by means of. a pipe 56 to the inlet of the nozzle 23 and a right-hand portion connected to the outlet side of said nozzle by means of a pipe 51. The left-hand end of the rack 52 is connected to a barometric pressure responsive device including a bellows 58. If. with this arrangement the flow of fuel increases, the piston 53 in cylinder 54, which in substance represents a flow-responsive device, is moved towards the right and thereby causes the cam 49 to rotate in clockwise direction, resulting in an opening movement of the valve 28 and accordingly an increased flow of air in the conduit I1. If the barometric pressure increases, the bellows 58 collapses somewhat and causes the rack 52 to move to the left, resulting in a closing movement of the valve 28. Similar operations take place with movements in opposite directions if the fiow of fuel in the fuel conduit 23, and the barometric pressure decrease. The device shown in Fig. 2 does not include any means for controlling the flow of air in response to changes in the relative speed between the conduit I1 and the current of air outside the conduit.

In both arrangements of Fig. l and Fig. 2 the control means for the valve 28 are connected together, that is, in Fig. l the two flow-responsive devices 25 and 26, as well as the barometric pressure responsive device 29 are connected to a common lever 38, and in Fig. 2 .both the flow-responsive device 53, and the barometric pressure responsive device 58 are rigidly connected to the rack 52.

In Figs. 3 and 4 I have shown arrangements in which the three control devices may act independently from each other, that is, movement of the one has no direct effect and particularly does not exert a biasing force on the other. This is accomplished in the arrangement shown in Fig. 3 by providing the air inlet conduit I! for the blower with three branches 60, GI and 52, of which each includes a-valve means 63, 64 and 65 respectively. The valve 63 in branch 66 is controlled by a barometric pressure responsive device 66. The valve 64 in branch 6| is controlled by a flow-responsive device 61 connected to the fuel supply conduit 23 corresponding to the con- Cir duit 23 in Figs. 1 and 2. The valve 65 in branch 62 is controlled by a flow-responsive device 69 including pipes 10 and H connected to the nozzle 24 in the conduit H. The flow-responsive devices 61 and 69 are similar to the flow-responsive devices 25 and 26 in Fig. 1 except that each includes a biasing spring 12 and 13 respectively.

During operation, a decrease in barometric pressure causes expansion of the bellows 66 whereby the valve 63 is opened and the flow of air through the branch 60 is increased. Similarly, an increase of flow of fuel through conduit 23 causes the diaphragm of. the flow-responsive device 61 to be forced downward to effect opening of the valve 64. An increase in the flow of air through the conduit I'I, due to a change in relative speed between the conduit H and the current of air, causes the flow-responsive device 69 to close the valve 65.

In Fig. 4 I have shown an arrangement in which the valve 28 in the suction conduit 11 of the blower is connected to a floating lever 13 The lefthand end of the floating lever is pivoted to the bellows 14 of a barometric pressure responsive device 15 and the right-hand end of the floating lever 13 is linked to an intermediate point of another floating lever 16. The rightehand end of the latter is connected to a device 11 responsive to the flow of fuel in the conduit l3, and the left-hand end of the floating lever 16 is connected to a device 18 responsive to the flow of air in the conduit ll. This is a preferable arrangement because the control of each device is independent from the positions of the other devices. During operation, an increase in barometric pressure causes the left-hand end of lever 13 to move up, the lever thereby turns about its right-hand end as a fulcrum and causes closing of the valve 28. An increase in flow of fuel in conduit I3 causes the right-hand end of the lever 16 to move down, the lever 16 thereby turns about its left-hand end as a fulcrum and due to its connection with lever I3 causes the latter to turndown about its left-hand end as a fulcrum,

resulting in opening of the valve 28. A decrease in flow of air through conduit I1 causes in a similar manner through the flow-responsive device IS an opening movement of the valve 28.

The mechanism so far described represents an arrangement for automatically controlling the supply of fuel and air to a furnace. Located in the furnace are containers or he'aders l9 and 89 connected by tubes ill for containing liquid such as water or mercury to be heated and evaporated. Heat is transmitted to the containers and the tubes by radiation and conduction. The fire gases escape through a flue 82 which has an opening in rearward direction of the aircraft. The elastic fluid produced in the boiler is supplied to a consumer shown as an airplane turbine or main turbine 83 driving a propeller 89 through the intermediary of a reduction gearing 65. A turbine of this type is more fully disclosed in my copending application Serial No. 632,932, filed September 13, 1932. The path of fluid between the boiler and the turbine is defined by a conduit 86, a chest ill and a conduit 89 between the chest and the inlet of the turbine. The turbine has an exhaust conduit 8.9 connected to a condenser 90 for condensing the exhaust elastic fluid of the turbine.

The condensate is returned to the boiler through the intermediary of a preheater which forms a part of the elastic fluid generator. In the present instance I have shown three preheaters 9|, 92 and 93. The condensate is pumped through the preheaters into the boiler. This is accomplished by the provision of two pumps 94 and 95. The suction conduit of pump 94 is connected by means of a conduit 96 to a well 91 which receives the condensate from the condenser 9D. The discharge conduit of the pump 94 is connected by a conduit 98 to the inlet or suction conduit of the pump and a discharge conduit 99 of the latter is connected to the preheater 9|. The two pumps and the three preheaters as will be readily. seen are connected in series. The preheater 93 which is the last preheater as regards the direction of flow of fluid through the preheaters discharges into the lower header 80 of the boiler through a conduit I20 including a check Valve l2l. The boiler feed liquid passing through the preheater 93 is heated by means of elastic fluid extracted from an intermediate stage of the turbine. In the present instance I have shown a conduit I09 including a check valve llll for conducting elastic fluid from an intermediate turbine stage to the preheater 93. Similarly the fluid passed through the preheater 92 is preheated by elastic fluid extracted from a lower stage of the turbine by a conduit I02 including a check valve I03. The heating fluid supplied to the preheater 93 is drained therefrom and supplied to the preheater 92 through a conduit I04 including a drip valve or an orifice I05, and the heating fluid supplied to the preheater 92 together with the condensated heating fluid received from the preheater 93 is conducted to the preheater 9| through a conduit I06 including a drip valve or an orifice I07. The heating fluid is drained from preheater 9! through a conduit- I08 including a drip valve or an orifice I09 and conducted into the suction conduit 96 of the feed pump 94. No heating fluid is directly supplied from the turbine to the preheater 9!. This preheater receives heating liquid through the drip valve I01 from the preheaters 92 and 93 and therefore may be termed a drip preheater. The drip valves or orifices are provided to allow only condensate to flow out from the preheaters.

The pumps 96 and 95 for forcing make-up or boiler feed liquid into the elastic fluid generator are driven from the shaft 29 of the auxiliary turbine l9 through gearings H9 and I! ll respectively. Preferably I provide positive displacement pumps for feeding liquid into the elastic fluid generator whereby the amount of boiler feed liquid delivered by the pumps is primarily determined by the speed of the pumps which in turn is fixed by the speed of the motor or auxiliary turbine 09. Assuming again that the speed of the turbine i9 is regulated in response to demand for elastic fluid, then the supply of boiler feed liquid is regulated in response to the demand for elastic fluid from the generator. In addition I provide a control arrangement for regulating the feed water supply in response to changes in temperature of the elastic fluid in the boiler. This is accomplished by the provvision of a bypass H2 between the discharge and the suction conduits of the pump 95 and 2.

valve H3 in the bypass which is moved in response to temperature changes of the generated elastic fluid. The valve H3 has a stem connected to a diaphragm H5 of a pressure rcsponsive device. The valve is biased towards open position by a spring H6 surrounding the valve stem and the right-hand casing half of the pressure responsive device has a conduit H1 with a sealed end H8 projecting into a chest II9 of the boiler discharge conduit 86.

If during operation the temperature of the elastic fluid increases it causes expansion of a gas such as air entrapped in the conduit I I1 and the left-hand casing half of the pressure responsive device, to the effect that the valve H3 is moved towards closed position. This decreases the amount of liquid which is bypassed between the discharge conduit 99 and the suction conduit 98 of the pump 95 and accordingly increases the amount of boiler feed liquid delivered from the discharge conduit 99 to the preheater. The bypass I I 2 together with the temperature responsive device represent a means for automatically maintaining constant the temperature of the elastic fluid in the boiler, and the pumps together with the bypass and the temperature responsive device represent means for automatically regulating the amount of feed liquid to the .boiler in response to the demand for elastic fluid. The last named means together with the arrangement for supplying and controlling the supply of fuel and air to the furnace represent in substance means for automatically controlling the amount of elastice fluid generated in the boiler in terms of demand for elastic fluid.

The demand for elastic fluid depends upon a number of factors, primarily the speed of the propeller. The flow of elastic fluid to the turbine is regulated by means of a valve I22 connected to a fulcrumed lever I23 which in turn is connected by means of a link I24 to one arm of a bell crank lever I25 having its other arm connected by a link I 26 to an intermediate point of a fulcrumed hand lever I2'I. Movement of the hand lever to the left effects downward movement of link I24 and opening movement of valve I22 which thereby admits an increased flow of elastic fluid to the turbine. The increased flow of fluidto the turbine, that is, the increased demand for elastic fluid generated in the boiler necessitates an increased supply of fuel and air to the furnace and also an increased supply of make-up liquid to the boiler. This is accomplished by increasing the speed of the motor or auxiliary turbine I9, in the present instance, by increasing the amount of elastic fluid supplied to the turbine I9. The auxiliary turbine has an inlet conduit I28 receiving elastic fluid from a lower extraction stage of the turbine through a conduit I29 which in substance forms a continuation of the conduit I02. The conduit I29 includes a check valve I30 and has its lower end connected to conduit I 28 by means of a conduit I 3I including a valve I32. When the valve I32 is "fully opened, live elastic fluid may be supplied to the auxiliary turbine through a conduit I33 having one end connected to the joint between the conduits I 28 and I3I and its other end to the chest 81. A valve I34 for regulating the amount of live elastic fluid supplied to the auxiliary turbine is provided within the chest 81. The stem I35 of the valve I34 is pivoted to the right-hand end of a floating lever I36 which has its left-hand end connected to the stem I31 of the valve I32. The valve I34 is biased towards closed position by means of a spring I38. The downward movement of the stem I31 of the valve I32 is limited by an adjustable stop I39. Connected at an intermediate point of the lever I36 is a stem I40 to which is fastened a piston I4I slidably arranged in a dashpot I42. The piston has an opening I43 which permits communication and displacement of a fluid contained in the upper portion and the lower portion of the dashpot. The dashpot is pivoted to a fulcrumed lever I 44 which in turn is connected to the fulcrumed lever I23 by. means of a link I45. Connected to the piston is a pressure responsive device I46 comprising a casing I41, a bellows I48 having a top portion fastened to the casing I41 and a bottom portion fastened to a stem I49 which in substance forms an extension of the stem I40. The bellows is biased in downward direction by a spring I50 surrounding the stem I49. The pressure responsive device is subject to the pressure of the elastic fluid in the boiler through a pipe I5I between the casing I41 and the discharge conduit 86 of the boiler.

During operation, the opening movement of the lever I27, indicated by an arrow, causes downward movement of the link I24'and, as explained above, opening of the turbine admission valve I22 whereby the flow of elastic fluid to the turbine increases. The downward movement of the link I24 causes at the same time a downward movement of the left-hand end of fulcrumed lever I44. The dashpot I4I, together with the piston I43, thereby are moved downward owing to the fact that the comparatively short period of time during which the movement of the fulcrumed lever I44 takes place does not permit a substantial I displacement of fluid, which may be oil, between the upper and lower part of the dashpot. In other words, for short or sudden movements the dashpot acts like a rigid connection between the lever I44 and the piston I43. The movement of the lever I36 causes, at first, opening movement of the valve I32 which permits an increased supply of extraction elastic fluid to the auxiliary turbine. The valve I34 is retained in closed position by the biasing spring I38 until the valve I32 is fully opened, that is, until the left-hand end of lever I36 engages the adjustable stop I39. In this position further downward movement of the stem I40 causes opening of the valve I34 against the biasing force of the spring I38 to permit live elastic fluid being supplied to the auxiliary turbine.

Thus the valves I32 and I34 represent means for controlling the auxiliary turbine or the motor IS in response to movement of the regulating means, that is the valve I22 for the main turbine. The auxiliary turbine or motor I9, together with the control means for this turbine, the pumps, and the blower driven by said turbine. represent a means for automatically regulating the generation of live elastic fluid in the elastic fluid generator in response to demand for live elastic fluid, or, from another viewpoint, in response to movement of the regulating means for the main turbine.

The pressure responsive device I46 serves to adjust the regul"ting means for the auxiliary turbine in response to pressure conditions in the boiler. If the demand for elastic fluid increases, one or both of the valves I32 and I34 are opened to increase the supply of elastic fluid to the auxiliary turbine I9. This causes an increased supply of fuel and air to the furnace and feed water to the boiler. Whereas the increased demand for elastic fluid causes, at first, a drop in pressure in the boiler, the increased supply of fuel to the furnace thereafter causes a, rise in pressure. The rise in pressure effects through the pressure responsive device I46 a repositioning of one or both of the valves I 32 and I 34 to maintain substantially constant the power supply to the auxiliary turbine I9. More specifically, the rise in pressure causes the bellows to collapse against I49, together with the piston I43 move upward and effect closing movement of one or both of the valves I32 andl34. In case the valve I34 is already closed, the valve I32 will be further closed and if valve I34 is partly opened then this valve will first be closed and as soon as it has been shut the valve I32 may be partly closed. The closing movement of the valves takes place slowly owing to the provision of the dashpot. The dashpot cylinder in this case remains stationary whereas the piston I4I moves within the I dashpot, causing displacement of fluid between the upper and lower portions thereof through the opening I43 in the piston MI.

The auxiliary turbine I9 has been shown as having an exhaust connected by means of conduits I52 and I53 to the exhaust conduit 89 of the main turbine 83. The-elastic fluid generator is provided with a blow-off valve I54 in the discharge conduit 86. If the pressure in the boiler exceeds a predetermined value, the blow-off valve opens against the biasing force of a spring I55 to permit relieving of the elastic fluid pressure. The elastic fluid discharged through the blowoff valve is conducted through a conduit I56 which forms a continuation of the conduit I53 into the exhaust conduit 89 of the turbine.

Summarizing, a few of the important features of the operation of my elastic fluid power plant: In order to decrease the output of the turbine, to lower for instance the speed of an aircraft, the lever I2! is moved towards closing position, that is, towards the right. This effects closing of the turbine valve I22 and accordingly a decreased supply of elastic fluid to the tur- Y bine, and simultaneously a closing movement of one or both of the valves I34 and I32 for the auxiliary turbine whereby the speed of the latter decreases and automatically efiects a decreased gen- .eration of elastic fluid in the boiler. The pressure in the boiler thereby decreases and eflects through the pressure responsive device I46 a repositioning of the regulating means for the motor or auxiliary turbine I9 to maintain substantially constant the output of the latter.

A change in boiler temperature through the temperature-responsive device II5-III and the bypass I 02 for the feed pumping means automatically causes a charge in the supply of boiler feed liquid to the elastic fluid generator.

If the relative speed between the power plant and the curent of air, or the supply of fuel to the furnace, or the barometric pressure, changes, then the flow of air in the suction conduit of the -blower is accordingly automatically changed under action of the flow-responsive devices 25 and 26 and the barometric pressure-responsive device .39, so that under any condition the supply of air to the furnace is proportioned to maintain proper combustion of the fuel supplied to the furnace.

The entire operation of the elastic fluid power plant is automatic. All that is necessary to change the operation is to move the lever I21 towards opening or closing position. Movement towards opening position causes an increased load output of the turbine and towards closing position a decreased load output. The complete automatic operation of the power plant is of particular significance in case the power plant is used in connection with an aircraft because it does not need the attention of a special operator but can be handled by the pilot of the aircraft. The le- 'ver I21 which is the main controlling lever for the entire power plant may be easily arranged in reach of the pilot. Movement of this lever effects a. change in the supply of elastic fluid to the main turbine. This change rapidly causes an automatic positioning of the various regulating devices in accordance with the changed demand for load output.

Having described the method of operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof, I desire to have it understood that the apparatus shown is only illustrative and that the invention may be carried out by other means.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In an elastic fluid generator, the combination of a furnace, means including a pump for supplying fuel to the furnace, means including a blower having a suction conduit for supplying air to the furnace to maintain combustion, valve means in the suction conduit, andmeans for positioning the valve means in response to the barometric air pressure, the velocity of the current of air outside the suction conduit, and the flow of fuel to the furnace.

2. In "a power plant, the combination of an elastic fluid generator comprising a furnace, a boiler, a fuel pump and a boiler feed pump, an auxiliary turbine for driving said pumps, a main turbine connected to the boiler, means for regulating the supply of elastic fluid to the main turbine, conduit means for conducting elastic fluidfrom an intermediate stage of the main turbine and from the boiler to theauxiliary turbine, and valve means in said conduit means connected to the regulating means for the main turbine.

3. In a power plant, the combination of an elastic fluid generator comprising a furnace, a boiler a fuel pump and a boiler feed pump, an auxiliary turbine for driving said pumps, a main turbine connected to the boiler, means for regulating the supply of elastic fluid to the main turfor controlling the valve means in response to changes of fluid condition in the boiler.

i. In a power plant, the combination of a boiler, means including a motor for regulating the generation of elastic fluid in the boiler, a main turbine connected to the boiler, an admission valve for the main turbine, means for controlling the admission valve, means for controlling the motor in response to movement of said admission valve and pressure changes in the boiler,

5. In a power plant, the combination of a boiler for generating elastic fluid, a main turbine connected to the boiler, valve means for controlling the supply of elastic fluid to the main turblue, and means for'automatically controlling the generation of elastic fluid in the boiler comprising an auxiliary turbine, a conduit including a valve for conducting live elastic fluid to the auxtermediate stage of the main turbine to the auxiliary turbine, a dashpot having a pistonconnected to the two last named valves and a cylinder connected to-the main turbine valve means, and

a device responsive to changes in fluid condition of the live elastic fluid in the boiler connected to the dashpot piston.

6. In a power plant for an aircraft, the conibination of a boiler, a turbine for driving a propeller receiving elastic fluid from the boiler, a condenser for the turbine, means including a preheater receiving condensate from the condenser and heating fiuid from an extraction stage of the turbine for automatically supplying condensate to the boiler in response to the demand for elastic fluid and temperature changes in the boiler, a motor for operating the last named means, and means for controlling the motor in response to the demand for elastic fiuid and the pressure of elastic fluid in the boiler.

'7. In a power plant, the combination of an elastic fluid generator comprising a boiler and auxiliaries, a main turbine connected to the boiler, said auxiliaries including an auxiliary turbine, a first conduit including a first valve between an extraction stage of the main turbine and the auxiliary turbine, a second conduit including a second valve between the boiler and the auxiliary turbine, a main valve for the main turbine, and

a mechanism for transferring movement of the main valve to said first and second valves.

8. In a power plant, the combination of an elastic fluid generator comprising a boiler and auxiliaries, a main turbine connected to to the boiler, said auxiliaries including an auxiliary turbine, a first conduit including a first valve between an extraction stage of the main turbine and the auxiliary turbine, a second conduit including a second valve between the boiler and the auxiliary turbine, a main valve for the main turbine, a mechanism for transferring movement of the main valve to said first and second valves, and means for normally biasing the second valve towards closing position and permitting opening thereof in a certain position of the first valve.

9. In a power plant, the combination of an elastic fiuid generator comprising a boiler and auxiliaries,, a main turbine connected to the boiler, said auxiliaries including an auxiliary turbine, a first conduit including a first valve between an extraction stage of the main turbine and the auxiliary turbine, a second conduit including a second valve between the boiler and the auxiliary turbine, a main valve for the main turbine, a mechanism for transferring movement of the main valve to said first and second valves, and means for positioning the first and second valves in response to changes in elastic fluid conditions in the boiler, said means being independent from the transferring mechanism.

10. In an elastic fiuid generator, the combination of a furnace, means including a first conduit for supplying fuel to the furnace, other means including a second conduit having a plurality of parallel branches for supplying air to the furnace, a valve in one of the branches, means for controlling the valve in response to fiow of fuel in the first conduit, another valve in another branch, and other means for controlling the other valve in response to changes of air condition in the second conduit.

11. In an elastic fiuid generator, the combination of a furnace, means including a pump for supplying fuel to the furnace, means including a blower having a suction conduit for supplying air to the furnace to maintain the combustion, valve means in the suction conduit, means for positioning the valve means comprising a barometric air pressure responsive device, and other devices responsive to the fiow of fuel and the flow of air, and a mechanism for connecting the devices to the valve means to permit independent control of the valve means by each of the devices.

12. In a power plant, the combination of an elastic fluid generator comprising a furnace, a boiler, a fuel pump, a boiler feed pump, an auxiliary turbine for driving said pumps, a main turbine connected to the boiler, means for regulating the supply of elastic fluid to the main turbine. conduit means for conducting elastic fluid from an intermediate stage of the main turbine to the auxiliary turbine, and other conduit means including a valve for temporarily conducting elastic fiuid from the boiler to the auxiliary turbine in response to sudden increases in demand for load output from the main turbine.

GLENN B. WARREN.

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