US1856616A - Power plant - Google Patents

Description

' Patented May 3, 1932 KARL BAUMANN, OF 'U'RMSTON, ENGLAND, ASSIGNOR TO WESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA POWER PLANT Application filed July 18,1930, Serial No. 468,915, and in Great Britain August 16, 1929.

My invention relates to steam power systems in whichthe steam passesrepeatedly through a closed cycle, being generated in a boiler at relatively high temperature and pressure and after giving up heat in the sys- 'tem being condensed and returned as feed water to the boiler.

My invention has for its object to provide means for overcoming a disadvantage which is more particularly noticeable in systems in which live steam is employed for reheating purposes, as a result of which considerable quantities of water may be formed at a relatively high temperature and it is desirable to return this water to the boiler with as little reduction of the temperature or loss of pressure as possible. The disadvantage in question arises from the use of a pump to return this water to the boiler, there being consider- "2 0 able difficulty in preventing leakage at the glands of the pump with consequent loss of water and heat energy, whilst it the glands are liquid sealed a cooling effect is produced thereby which results in loss or degradation of heat.

According to the present-invention, however, means are provided for returning to the boiler water condensed from the motive steam, comprising a closed receptacle which is adapted to be cooled for example by feed water before its entry to the boiler and which has a connection with the steam space of the boiler, a valve whereby said connection may be opened or closed, a drainage connection with the boiler or with the high pressure side of the feed water system, a non-return valve in said drainage connection, and a pipe through which the said condensed water may be conducted to the receptacle, said pipe being also provided with a non-return valve. By this means the use of a pump for the purpose referred to may be avoided, it being only necessary to open and close from time to time the valve which controls'the connection between the receptacle and the steam space of the boiler. Upon opening saidvalve, steam at the temperature and pressure prevailing in the boiler is permitted to enter the said receptacle and with the equalization of the pressure. the water in said receptacle may drain into the boiler. Upon closing said valve the steam shut in the receptacle is cooled and may partially condense, thereby causing a reduction in pressure in the receptacle whereby the water condensed from the steam in the reheating apparatus or the like may be drawn into the said receptacle. The heat taken up in cooling the steam in the receptacle is conserved in the feed water which effects this cooling and is eventually returned to the boiler.

A steam power system is shown diagrammatically in Fig. 1 of the accompanying drawings which illustrates by way of example a preferred arrangement of apparatus embodying the invention.

Fig. 2 shows a float control mechanism for the apparatus illustrated in Fig. 1.

he power system in this example includes a steam turbine or a turbine assembly comprising a high and low pressure turbine 1 and 2 respectively in which the motive steam is passed through a reheater 3 at the intermediate stage of its expansion. This reheater 3 is supplied with superheated steam tapped off the main supply 4 from the superheater 21 leading to the high pressure turbine portion 1, and condensation of the steam takes place in thereheater. The condensed steam is drained oil into a drainage vessel 5 which is preferably of approximately equal capacity to a receptacle 6 which is disposed some what above the normal water level inthe drum 7 of the boiler 20 to which drum it is connected by a drainage connection 8. The said drainage vessel 5 and receptacle 6 are connected by a pipe 9 in which is disposed a non-return valve 10 adapted to permit the passage of fluid from the drainage vessel 5 to the receptacle 6, but not in the reverse direction. A non-return valve 11 is also provided in the drainage connection 8 which is adapted to prevent the flow of fluid therethrough from the boiler 7 to the receptacle 6.

The receptacle 6 is provided with a cooling coil 12 or the like through which the feed water flows in its path in the connection 19 from the condenser 13 to the boiler 7. The feed water may be heated progressively by passage through feed heaters 14, 15, 16 supplied with steam preferably tapped from the low pressure turbine portion 2, before being utilized for cooling the receptacle 6. The

latter is connected at the top. with the steam space of the boiler drum by a pipe 17 in whicl is provided a control valve 18.

The system is operated as prevlously stated.

When the control valve 18 is opened the receptacle is filled with steam, any watertherein draining into the boiler/T. Upon will consequently drop and water from the reheater' 3 accumulating in the drainage vessel 5 will be forced into the'receptacle 6. Upon again opening the' control valve 18 steam enters theireceptacle 6 from the boiler 7 while the water in the receptacle drains into the boiler through the connection 8 and the non-return valve 11.

The alternate filling and draining of the receptacle 6 maybe carried on indefinitely, the control valve 18 'beingoperated manual.- ly or automatically asmay be preferred. In the case of automatic operation, this may take place at predetermined intervals or at intervalsdependent upon the quantity of water to be disposed of, for example by the aid; of float mechanism or other water level responsive apparatus associated with the receptacle. Thefloat mechanismor other water level responsive apparatus opens the valve 18 when the level of the condensed steam in the re- 1 ceptacle6 rises to-a'pr-edetermined upper level, and closes the valve when the condensate 1 level falls to .a' predetermined lower level. A constructional example of float control mechanism which may be used is shown in- Fig.2. The control valve 18 is connected to a piston 22 disposed in a cylinder 23. The piston 22 is biased in valve closing direction by a spring 24 and it'is adapted to .be moved in valve openingdirection by fluid pressure conveyed through a conduit 25 and controlled by a three-way valve 26. The-latter is adapted to place the conduit 25 in communication withsomesuitable source of fluid pressure, such asthe boiler 7, through a conduit 27, or to place the conduit 25 in communication with a discharge opening 28through which the fluid pressure maybe exhausted to the atmosphere. Thethree-way valve 26. is 'actuatedby a lever 29, to which there is connected a'rod 31fwhich extends into the re- .ceptacle-6. A float 32 is slidably mounted on the rod 31 between two collars 33-and3 l which are fixed to the rod 31 adjacent the upper andlower ends, respectively, of the receptacle 6.- V 7 1 The float 32 floats on the surface of the liquidin the receptacle 6. When the liquid rection to place the conduits 27 and25 in communication. Fluidpressure is applied to the piston 22 in valve opening direction, and the control valve 18'admits steam to the receptacle 6 to permit the liquid to drain to the boiler 7. the levelpfthesliquid descends, the valve 26 remains inthe position to which it has been moved until the level of the liquid approaches the bottomof the receptacle 6 when the float 32 abuts the collar 3 l'to move the rod 31 downwardly. The valve 26 is then moved in clockwise direction to place the conduit 25 in communication with the atmosphere through the discharge opening 28. Fluid pressure is discharged from the cylinder 23 and the spring 24 moves the piston 22 in valve closing direction. The supply of steam through the control valve 18 is shut off and steam in the receptacle 6 is condensed toidraw. in the condensate from the vessel 5 as alreadydescribed. The float control mechanism shown in Fig. 2 comprises conventional and well known control apparatus. The specific construction thereof forms no part of the present invention, which contemplates the float control mechanism merely as one element of the invention.

It may not be necessary to pass all the boiler feed waterthrough the cooling coil 12 or apparatus ofthe receptacle 16, but only a portion" of the available feed water may suffice in some cases, either before or after its passage through feed water heaters 1d, 15, 16, economizers, or other apparatus. The supply of feed waterfor cooling the receptacle 6 5 may flow intermittently, for example only when the. control valve18 is shut, but being by-passed when the'control valve is open.

Theireceptacle 6 and the cooling coil 12' or apparatus thereof may be designed as a feed I water heater proper, working intermittently in accordance with the cycle described.

It will-be evidentthat by means such as above set forth the disadvantages above referred to and inherent in the use of'a pump for the purpose in question may be avoided, the loss of heat and the loss of power incurred in operating the control valve being exceedingly small.

- While the invention has been more particularly described above in connection with reheaters, it will be apparent that it may be readily applied to other portions of a steam powersystem for the purpose of returning to the boiler steam condensed and collected at drain valves or other parts of the system, and where the employment ofa mechanical pump is attended with disadvantages.

VihileI have shown my invention in but one form, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various changes and modifications, without departing from the spirit thereof, and I desire, therefore, that only such limitations'shall be placed thereupon as are imposed by the prior art or as are specifically set forth in the appended claims.

What I claim is: 1.' In a high pressure elastic fluid power system arranged for returning the condensate from a motive fluid reheater to the boiler without. a mechanical pump, the combination 7 of a boiler, a turbine comprising a high pressure portion and a low pressure portion,

I 10 means for conveying elastic fluid from the boiler to the high pressure turbine portion, a reheater for the motive fluid flowing from the high pressure portion to the low pressure portion, means for conveying elastic fluid from the boiler to the reheater as heating medium and condensing the same therein, a closed receptacle, a conduit for conveying condensate from the heater to the receptacle and including a check valve permitting flow toward the closed receptacle only, a drainage connection between the bottom of the receptacle and the boiler and containing a check valve permitting flow toward the boiler only, a pipe between the elastic fluid space of the boiler and the closed vessel, a valve in said pipe, a cooling pipe in the closed vessel, a condenser for the low pressure turbine portion, means for conveying the condensate from said condenser through said cooling pipe and then to the boiler, whereby when the last-mentioned valve is closed, the lastmentioned condensate condenses the steam in the closed vessel, causing the latter to draw in condensate from the reheater, and absorbs the heat of condensation from said steam and returns it to the boiler.

2. A steam power system, according to claim 1, further including water level responsive apparatus associated with said receptacle and in which the valve provided in the pipe connecting the said receptacle to the steam space of the boiler is operated automatically by said water level responsive apparatus, the valve being closed when the level of the condensed steam in the receptacle falls to a predetermined level and being opened when a predetermined upper level in the receptacle is reached.

In testimony whereof, I have hereunto sub- 59 scribed my name this 1st day of July, 1930.

KARL BAUMANN.

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