US1622675A - Steam plant - Google Patents

Description

March 29, 1927. J. RUTHS STEAM PLANT Filed April 13, 1925 Patented Mar. 29, 1927. v v

UNITED. STATES PATENT OFFICE.

J'OHANNES 'RUIHS, 0F DJURSHOLM, SWEDEN,ASSIGNOR TO AKTIEBOLAGET VAPOR- .ACKUMULATOR, OF STOCKHOLM, SWEDEN, A CORPORATION OF SWEDEN.

STEAM PLANT.

Application filed April 13, 1925, Serial No. 22,896, and in Germany May 21', 1924.

The present invention relates to the control of the passage of steam to a steam consumer from a vessel capable of rejecting a considerable quantity of st ,am in a short time and more specifically relates to an arrangement for limiting the amount of steam passing to a turbine from a steam accumulator, the arrangement being preferably controlled by the pressure in the accumulator. The object of the invention-is to prevent an undue supply of steam to a consumer, and thereby to prevent dangers arising from a possible oversupply of energy.

The invention is illustrated in one form in the accompanying drawing, in which reference character lddesignates the steam consumer, in the case shown a steam turbine, which receives steam from the accumulator 12 through conduits 11, 13 and 14, the flow of steam being regulated by valves 15 and 16 situated in conduits 13 and 14 respectively. Turbine 10 also receives steam from a steam generator 8 through conduit 17 controlled by valve 18. Valves 15, 16 and 18 are controlled by a speed responsive device 19 suitably connected to actuate arm 20 in response to changes of speed of rotation of the shaft of the turbine. Arm 20 controls successively ilot valves 21, 22 and 23, which control the ow of a pressure fluid through tubes 25, 26 and 27 to and from actuatingpistons 28, 30 and 32 which adjust the positions of valves 18, 15 and 16 respectively. The purpos" if this arrangement is to take steam first through the conduit 17 and then when the speed has decreased so far that valve18 is completely open, through valve 15 and upon further decrease of speed through valve 16.

The 0 eration of the above described parts is as fol ows:-

Su pose at'a' given load valves 15 and 16 are c osed and valve 18 controls the supply of steam to the turbine. I Now assume that the load increases gradually. The arm 20 'is moved in counter clockwise direction so that pilot valve 21 is raised and a greater amount of pressure is thereby produced on the lower side of piston 28 against the action of spi'in 29 and causing valve 18 to open more. Xssuming that the speed continues to decrease due to increased load, arm 20 is moved still farther in anticlockwise rotation, so that ilot valve 22 allows pressure fluid to pass into tube 26 and act upon the valves 15 and 16, which, with high upper side of piston 30 and against the action of spring 31, whereby valve 15 is opened and steam passes from the accumulator 12 to the turbine to give added power. Assuming that the load has risen to such an extent that the supply of steam'is still not enough, the arm 20 will next cause pilot valve 23 to afford communication between On further increase of speed pilot valve 22' then establishes communication between tube 26 and outlet 34, whereby valve 15 is closed and pilot valve 21, piston 28 and valve 18 then become again the controlling elements which regulate the amount of steam supplied to the turbine.

The accumulator feeding steam to the tur bine is often subject to very great changes of pressure, especially in cases where theaccumulator serves to afford an independence between the total steam consumption and steam production of a plant. In order to have suificient steam supply to the turbine, the operation of valves 15 and 16 must be based on substantially the lowest pressure existing at any time in the accumulator. Taking into consideration that the amount of energy supplied by the 'accumualtor to the turbine 18 proportional to the pressure in the accumulator, it can be seen that when the accumulator is at high pressure, it can deliver many times the amount of energy to the turbine for the same amount of opening of valves 15 and 16 than is possible at low values of pressure in the accumulator. Thus the condition may readily arise that, uponfa sudden increa e of load as, for example, if

the turbine 10 is a standby unit in a central electric station, and suddenly has to take over the whole load of the station, the speed governor 19 may cause a sudden opening of ressure in the accumulator, would sup y so much energy to the turbinemmd ro uce so much power that the turbine mig'it rupture or shafting be broken or windings burned in a generator or like accidents. I therefore propose to limit the flow through the conduits supplying steam from the accumulator to the turbine depending on the pressure in the accumulator, so that the danger of oversupply of steam on sudden increase of load will not arise.

To accomplish this I insert in conduit 11 a valve which is controlled in such a manner that it presents a small area to the flow of steam at high values of pressure in the accumulator and a greater area for flow at lower pressure in the accumulator. which is designated by reference character 35, may be of an type, but I prefer a nozzle valve of gradua ly expanding cross-section, since this type of valve changes the pressure energy of the fluid flowing through the same into velocity energy of the critical value and reconverts the velocity energy into pressure energy in a manner that avoids the losses incident to an ordinary disc type throttling valve. The valve may be controlled in a variety of ways. I prefer an automatic regulation and have shown more or less diagrammatically one form adaptable to perform the desired operation, which includes a cylinder 36, in which a piston 37 moves in response to changes of pressure in a pressure fluid such as water or oil, conducted to or from the cylinder valve by means of tube 38 and controlled by pilot valve 39. To the piston 37 is attached a piston rod 40, which in turn is attached to one end of .a flexible member such as chain 41, which passes around pulley 42, and over pulley 43 and to the opposite end of which is attached a connter-weight 44. Pilot valve 39 consists of a grooved cylinder so arranged that upon movement to the left it establishes communication between supply tube 45 for the pressure fluid and tube 38, while upon the movement to the right it establishes communication between waste conduit 46 and tube 38. The pilot valve 39 is moved by pressure acting in chamber 47 on bellows dia hragm 48, opposed to which is the force 0 spring 49 the movement of the diaphragm being transmitted through rods 51 and 52 and lever 53. Lever 53 is also arranged to be moved by piston rod 40 to provide return motion. Chamber 47 is connected to the steam space of the accumulator by means of tube 50.

In operation of the device, different pressures in the accumulator cause proportionately different positions of bellows diaphragm 48 andcorresponding different positions of valve 53. Suppose, for example, that the pressure in the accumulator rises a given number of pounds. The rise in pressure acts in chamber 47 and due to the action of spring 49 the left hand end of bellows48 will move a distance corresponding to the amount of rise of pressure. Pilot valve 39 is as a result moved to the right, thus estab- The valvelishing communication between tube 38 and left causes a'movement of .the upper part of lever 53 to the left whereby pilot valve 39 is returned to neutral position, and the motion of piston 37 is stopped and the valve 35 becomes stationary at a ditferentposition than before the operation of the regulating mechanism.

If the pressure decreases in the accumulator, spring 49 overcomes the pressure of vapor in chamber 47, and rod 52 moves to the left carrying pilot valve 39 to the left, so that communication is established between supply conduit 45 and tube 38 thus moving piston 37 to the right and increasing the opening through valve 35 until lever 53 has returned the pilot valve to neutral position.

lVhile I have shown one form of apparatus for performing the new operation of the invention, it will be obvious that varied changes may be made within the scope and spirit of the invention.

The control for the valves of the turbine is to be understood to be merely diagrammatic and any known control may be used for this purpose, and it is to be understood that the showing and description of turbine and control therefore is introduced merely to show one application of my invention.

It is obvious that the apparatus and method herein set out is applicable to other elastic fluids than steam, and other-sources than a steam accumulator.

Further the valve 35 may in certain cases be controlled by hand as when the accumulator stands fully charged for the greater part of time and only comes into operation at intervals.

Having thus described my inventionwhat I claim is:

1. In a steam plant, in combination, a steam generator, a motor, means to conduct steam from said generator to said motor, a

steam accumulator normally operating under relatively great variations of pressure, a passage for steam from said accumulator to said motor, a valve in said passage and control means for said valve operating in response to changes of pressure in the accumulator to change the area of flow through said valve in inverse proportion to the pressure in the accumulator.

2. In a steam plant, in combination a steam generator, a motor, means to conduct steam from said generator to said motor, an

accumulator normally operating under relatively great variations of pressure, a passage and means to adjust said valve to cause a small area of flow through the same when the pressure in the accumulator is high and a greater area of flow when the pressure is low in the accumulator.

3. In a steam plant, in combination, an accumulator normally operating under rela-' tively great variations of pressure, a motor, a passage for steam from said accumulator to said motor, a valve in said passage, and mechanism movable in response to changes of pressure in said accumulator and operating to change the position of said valve, and to return said mechanism to neutral position upon movement of the valve and to maintain a different given position of said valye for each diiferent value of pressure in the accumulator.

4. In a steam plant, in combination, an accumulator normally operating under relatively great variations of pressure, a motor,

a passage for steam from said accumulator -to said motor, a valve of gradually expanding cross section in said passage, and mechanism movable in response to changes of pressure in said accumulator and operating to change the position of said valve, and to return said mechanism to neutral position upon movement of the valve and to maintain a different given position of said valve for each different value of pressure in the accumulator.

5.In a steam plant, in combination, a primary source of steam supply, a secondary source of steam supply normally operating under relatively great variations of pressure, a consumer, means to supply steam from said primary source to said consumer, a passage for steam from said secondary source of steam supply to said consumer and an adjustable expanding nozzle in said passage.

6. In a steam plant, in combination, a steam generator, a motor, means to conduct steam from said generator to said motor, a steam accumulator normally operating under relatively great variations of pressure, a passage for steam from said accumulator to said motor, a valve of gradually expanding cross-section in said passage, mechanism movable in response to changes of pressure in said accumulator and operating to change the minimum cross-sectional area of flow of said valve, said mechanism including a relay member adapted to have different positions for different values of pressu e in the accumulator, a servo-motor operated by said relay member and means operatedon movement of said servo-motor to check the action of the servo-motor in changing the area of flow of the valve dependent on de cc of movement of the relay member so tiizt the valve is adjusted to' diflerent positions for diflerent positions of the relay'member, the amount of opening of the valve varying inversely with respect to values of accumulator pressure.

In testimony whereof I hereunto afiix my signature.

J OHANNES RUTHS.

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