US1629028A - Steam-condensing and boiler-water-supply apparatus of steam-power plants - Google Patents

Description

May H. FOTHERGILL ET AL v STEAM CONDENSING AND BOILER WATER SUPPLY APPARATUS OF STEAM POWER PLANTS Fi'led Oct. 9, 1926 e Sheets-Sheet 1 A IG.. 0 R

L F C /NVENT0Q S I v 1,629 028 May 1927' F1. FOTHERGILL ET 'AL I swam CONDENSING AND BOILER WATER SUPPLY APPARATUS OF STEAM POWER PLANTS Filed Oct. 9, 192 2 Sheets-Sheet 2 INVENT02 HARQY Fo'rHEQbILL HAQOLD HH- ER 1 Mm! mmd Patented May 17, 1927.

UNITED STATES HARRY FOTHERGILL AND HAROLD HILLIER, OF WESTMINSTER, LONDON, ENGLAND.

STEAM-CONDENSING ANDLOILER-WATER-SUPPLY APPA ATUS or STEAM-POWER PLANTS.

Applicationfiled October 9, 1926, Serial No..140,626, and in Great Britain December 16, 1925.

In order to prevent corrosion in boilers and economizers it is now common practice to design steam power plants so that the feed water is delivered to the boilers practically free from air. The elimination-of air may be eliected by introducing into the feed system a deaerator through which the water required for boilerfeeding pur poses isdelivered on its way to the boiler. However, in plants where the condenser is designed to provide a very low partial air pressure at'the condensate outlet, the quantity of air contained in the condensate is very small, and provided it is convenient to deliver the condensate from the condenser to the boilers through a closed circuit corrosion troubles may be overcome.

Such an arrangement precludes the use of a free connection between the feed or surge tank and the feed line, and the ab sence of such a connection means that a special automatic device must be provided to admit water into, or from, 'thesystem in accordance with the requirements of the feed pump, which may at times demand quantities of water Widely different from the quantities of water condensed in the main condenser. p

These conditions involve sudden demands on the feed pump which are usually of short duration, and correspond to the pe riods during which sudden variations in the steaming rate of the boiler increase'or decrease ebullition which lifts or lowers the boiler water level irrespective of variations in thefeed water supply.

In a closed feed system, it is usual to discharge the surplus water from the feed system through a valve into the feed tank, and to supply any makeup or "additional water intothe feed system through another alve into the main condenser, so that such water will be deaerated before entering the feed system.

Hitherto, in arrangements of this kind it has been usual to operate the valves by connecting them mechanically with a float, and when hydraulic means have been adopted for operating the valves it has been necessary to provide two floats, arranged to operate at different Water levels, so that one float will control the admission of water to the system at a low level, while the other float will control the discharge of water form the system at a high level. Such proved arrangements, besides being complicated, are liable to derangement, which is a very serious defect in power'plants carrying heavy loads. a I

The present invention consists of animconstruction and arrangement whereby the valve or valves controlling the admission or discharge of water from the system are operated by pressure under control of a single float. A further feature of the invention is theprovision, when reuired of means for movin the valve or vsets of ports or openings, one set for the admission of water and the other set for 'thedischarge'of water, such ports being opened or closed by a piston or pistons or the like which move across the ports under the action of the float.

Whichever arrangement is adopted, we provide a piston or the equivalent which may be separate from or form part of the valve or valves, and the space on one side of the piston is connected to a water pressure supply, while the other side of the piston is subjected to a'lower pressure, but high enough to move the piston when the water pressure on the other side is released.

The higher water pressure may-be applied to the piston either by controlling the admission of water to the piston cylinder or the escape of water therefrom, such control being actuated by the float depending on the water level on the suction side of the condensate pump. I

The accompanying drawings illustrate diagrammatically by way of example convenient forms, of our invention, the same letters of reference being used to denote similar parts. Figure 1. shows in section one particular form of the automatic valve for'controlling the admission to and discharge of water from a closed feed system, and Figure 2 illustrates the application to a closed feed system of the valve shown in Figure 1.

Figure 3 illustrates a modification of the automatic control valve shown in Figure 1.

With reference to Figures 1 and 2, the main condenser M is of the regenerative type, and is so designed that water admitted to the condenser from the pipe T will be deaerated on its passage through the condenser to the condensate extraction pump W Which discharges into a closed system N to the boiler feed pump K. Air is removed from the condenser M through the outlet Y by any convenient type of air ejector.

The float F is operated by the Water level in the chamber H, which corresponds with the water level in the base of the main condenser M.

' The flow of water to and from the system is controlled by a simple piston P (see Figure 1). which moves across the ports A and B, and controls the delivery to or discharge of water from the feed tank as will hereinafter be described. The movement of the piston P is effected by the rise or fall of water pressure in the cylinder C below the piston, such pressure being controlled by the pointed spindle or needle valve D which opens or closes the water outlet L in the piston P. The water pressure may be obtained from any convenient source, prefen ably from the discharge of the condensate extraction pump V, to which the cylinder C can be connected by the small pipe P.

With such arrangement, it will be seen that the piston P will float up or down in accordance with the movement of the float F depending on the rise or fall of the water level in the base of the main condenser M. For example, if the float F rises, the spindle D will close the outlet L from the cylinder C, and the pressure of water will lift the piston P until an opening is again provided past the end of the spindle D. Similarly, when the float F falls, the spindle D will be withdrawn from the piston P. thus permit-- ting the water to flow away from the cylinder C, through the outlet L and the piston P will be forced down by atmospheric pres sure until the outlet L is again closed by the needle valve D. It will thus be seen that the piston P will follow the in-oven'ient of the valve D without any mechanical connection, and by being hydraulically operated in this manner a positive movement is obtained without the use of a large and cumbersome float such as is necessary when the piston is directly connected to the float lever. With the arrangement described there is no chattering and the piston moves freely up or down corresponding, to the water level in the condenser. Vhen the piston P is in its upper position, the branch R is placed in communication with the branch S. and water flows from the feed system N into the feed tank X. When the piston P is in its lower position, the branch T is placed in communication with the branch 5 and water flows from the feed tank X into the condenser M; while when the piston P is in its midposition (as shown in Figure l) the ports A and B are closed, and there is no flow of water through the valve.

A removable cover U'is provided so that the piston P may be quickly withdrawn for inspection or cleaning without breaking any pipe connections.

This cover U may also have attached to it a hand operating gear Gr consisting of a screw lift spindle Q, which tern'iinates in a shoulder O. A space is provided in the piston P above and below the shoulder O so that in its normal position the spindle Q, does not interfere with the action of the piston, but when the spindle is screwed up or down the shoulder O can be used for holding the piston at either end of its stroke. It will thus be seen that in the event of the derangementof any part of the plant the piston P can be lifted and held in its upper position by means of the hand gear Ur. WllOl' the branch R will remain in free communi- "ation with the branch S. This is specially advantageous because in the event of derangement the feed system N can be inn-nediately opened to the feed tank X by means of the hand gear G, so that the feed pump K can draw water direct from the feed tank X until the fault is remedied.

A handle J. which normally does not engage with the float lever, is also provided, so that the float F may be lifted or depressed in order to ascertain whether the float and piston are free and functioning properly.

The object of the arrangen'ient is always to supply the feed system N with deaerated water, and aut-on'iatically to balance the requirements of the feed pump K.

The first effect is obtained by passing through the main condenser M all water required for boiler feeding, purposes. No water can enter the feed system N from the feed tank X except by passingthrough the branch T into the main condenser M, wherein it is deaerated. The second effect is 01 tained in the following: manner.

Suppose that on starting the main turbine, the increased ebullition in the boiler lifts the water level and causes the feed regulator to close the check valve and cut oil the supply of water to theboiler, then the steam condensed in the condenser M is greater than that required by the boiler feed pump ii. Under such conditions the water level in the base of the condenser rises. and the float F causes the piston P to pass the surplus water from the feed system N through the branches R and S into the feed tank X.

Under normal conditions the water in the base of the condenser settles down toa level at which the float F causes the piston P to open slightly to the main condenser, sothat the necessary quantity of make-up water will be drawn from the feed tank X through the branches T and S into the condenser M. This make-up water is deaerated in the con denser, in accordance with well-known principles, and passes with the main condensate through the condensate extraction pump V, which 'maintains a pressure on the suction side of the feed pump K.

When the steam condensed in the main condenser M is insufficient for the require ments of the boiler feed pump K, as may happen with a sudden reduction of load on the main turbine, the water level in the base of the condenser falls, and the float F causes the piston P to pass water from the feed tank X through the branches S and T into the condenser until the water level therein is restored, and the requirements of the feed pump are satisfied.

In Figure 3, which is a modification of Figure 1, the flow of water through the branch R is controlled by a simple nonretnrn valve V which is lifted by the spindle of the piston P during the upper portion of its stroke. The distance travelled by the piston P after closing the ports B and before it opens the valve V, represents the lost motion period during which both valves are closed, and this period can be increased by leaving a space Z between the two valves. In Figure 3 the leak-off from the cylinder C takes place through an extension of the piston which passes downwardly into the float chamber H and is provided with outlets Lvvhich are closed or opened by the spindle D as described with reference to F igure' 1.

With either of the arrangements described in Figures 1 and 3 the valves are operated entirely by hydraulic pressure as distinguished from the action of springs, which are not only complicated but are frequently unreliable. Further by making the piston P of sufficient diameter any desired force can be obtained for operating the valves.

lVhat weclaim and desire to secure by Letters Patent is:

1. A closed boiler feed system comprising a condenser, a condensate extraction pump connected on its suction side to the condenser, a float chamber arranged on the suc the float falls, or in to the system on the (le livery side of the condensate extraction pump when the float rises. V I

2. A closed boiler feed water system com-. prising acondenser, a condensate extraction pump connected on its suction side to the condenser, a float chamber arranged on the suction side of the condensate extraction pump and having a water level corresponding to the level 011 said suction side, a float in said chamber, a valve casing adjacent the float chamber, branches on said cas ing, a boiler feed pump, a feed tank,- a pipe connection from a branch on said valve casing to the closed pipe circuit on the suction side of the feed pump, a connection from a branch on said casing to the feed tank, :1 connection from a branch on said casing to the condenser, apressure operated valve in said casing operating to control the flow of water through said branches to establish sclectively alternative connection between certain of said branches, and a connection between said valve and said float whereby the operations of the valve are controlled in accordance with the'n'iovei'nents of said float.

3. A closed boiler feed system comprising a condenser, a condensate extractionpump connected on its suction side to the condenser, a float chamber arranged on the suction side of the condensate extraction pump and having a water lelvel corresponding to the level on said suction side, a float in said chamber, a piston valve arranged-in saidclosedsystem between the feed pump and the condensate extraction pump, said valve being associated with the float and adapted to be operated by pressure in accordance with the movements of the float to. cause water to be delivered through said valve, alternatively, to the condenser whcn the float talls. or to the system on the delivery side of the condensate extraction pump, when the float rises. i

i. A closed boiler feed water system comprising a condenser, a condensate extraction pump connected on its suction side tothe condenser, a float chamber arranged on the suction side of the condensate extraction pump and having a water level correspond.- ing to the level on said suction side, a. float in said chamber, a valve casing adjacent the float chamber, ports in said casing, a boiler feed pump, a feed tank, a pipe connection i'roin a port in said valve casing to the closed pipe circuit o'n'the suction side of the feed pump, a connection from a port'in said casing-to the feed tank, a connection from a port in said casingto the condenser, apiston valve in said casing open to by dranlic pressure on one side and co-operating with said ports, to establish selectively alternative connection between certain of said ports, and a connection between said valve and said'float whereby the operations of'the' valve are controlled in accordance with the movements of said float.

5. A closed boiler feed water system comprising a condenser, a. condensate extraction pump connected on its suction side to the condenser, a float chamber arranged on the suction side 01 the condensate extraction pump and having a water level correspcnding to the level on said suction side, a float in said chamber, valve casing adjacent the float chamber, ports in said casing, a boiler feed pump, a feed tank, a pipe connection from a. port in said valve casing to the closed pipe circuit on the suction side of the Feed pump, a connection "from a port in said casing to the feed tank, a connection from a port in said casing to the condensen a piston valve in said casing co-operating with said ports to establish selectively alternative connection betweencertain of said ports, a pipe connection leading from the delivery side oi" the condensate pump to one side of said niston whereby hydraulic pressure is applied to said piston and a connection between said valve and said float whereby the hydraulic pressure applied to said piston controlled and the operations of the valve are caused to correspond with the movcments of said float.

6.. A closed'boiler feed system comprising a condenser, a condensate extracting pump connected on its suction side to the condenser, a floatchamber arranged on the suc tion side of the condensate extraction pump and having a water level corresponding to the level on said suction side. a float in said chamber, a pressure operated valve connected in said closed circuit between the teed pump and the condensate extraction pump, means for admitting hydraulic pressure to one side of said valve. a leak o'li device for controllingthe hydraulic pressure and means associated with the float and adapted to be operated in accordance with the movement of the float to control the leak oft device and cause water to be delivered through said pressure operated valve. alternatively. to the condenser when the float falls, or to the system on the delivery side of the condensate extraction pump. when the float rises.

7. A closed boiler feed water system comprising a condenser, a condensate extraction pump connected on its suction side to the condenser. a float chamber arranged on the suction side of the condensate extraction pump and having a water level correspondin to the level on said suction side, a float in said chamber, a valve casing adjacent the float chamber, ports in said casing, a boiler feed pump, a feed tank, a pipe connection from a port in said valve casing to the closed pipe circuit on the suction side of the feed pump, a connection from a port in said casing to the feed tank, a connection from a port in said casing to the condenser, a pisnezaeza ton opera-tin said valve in said casing cooperating with said ports to establish selectively alternative connection bet-ween certain oil said ports, a hydraulicpressure supply leadingto one side of said piston operating valve, a leak oli port in said pistonfa leak oil valve co-oporating' with said leak ofl portand a connection between said float and said leak valve whereby the movements of the piston operated valve are controlled in accordance with the movements of said float.

8. A clor 'cd boiler feed system comprising a condenser, a condensate extraction pump connected on its suction side to the condenser. a float chamber arranged on the suction side ot the condensate extraction pump and having a water level corresponding to the level on said suction side, a float in said ,rhaniber, a pressure operated valve connect ed in said closed circuit between the feed pump and the. condensate extraction pump, said valve being associated with the float and adapted to be operated in accordance with the movements of the float, to cause water to be delivered through said valve, alternatively, to the system on the suction side of the condensate pump when the float "falls, or to a feed tank on the delivery side of the condensate extraction pump when the float rises- 9. A closed boiler feed water systen'i comprising a condenser, a condensate extraction pump connected on its suction side to the condenser, a float chamber arranged on the suction side of the condensate-extraction pump and having a water level corre sponding to the level on said suction side, a float in said chamber, a valve casing adjacent the float chamber, ports in said casing, a boiler feed pump, a teed tank, a pipe connection from a port in said valve casing to the closed pipe system on the suction side of the feed pump, a connection from a port in said casing to the feed tank, a connection from a port in said casing to the condenser, a pressure operated valve in said casing cooperating with said ports to establish selectively alternative connection between certain of said ports, and a connection. betweensaid valve and said float whereby the operations You and the condensate extraction pump, said valve being associated with the float and adapted to be operated by pressure in accordance with the movements of the float to cause water to be delivered through said valve, alternatively, to the condenser when the float falls, or to the system on the deliv ery side of the condensate extraction pump when the float rises, and hand operable means for actuating the valve at will irrespective of the water level in the float chamber.

11. A closed boiler feed system comprising a condenser, a condensate extraction pump connected on its suction side to the condenser, a float chamber arranged on the suction side of the condensate extraction pump and having a water level corresponding to the level on said suction side, a float in said chamber, a pressure operated valve connected in said closed system between the feed pump and the condensate extraction pump, means for admitting hydraulic pressure to one side of said valve, a leak off device for controlling the hydraulic pressure and means associated with the float and adapted to be operated normally in accordance with the movement of the float to control the leak oflf device and cause water to be delivered throu h said pressure operated valve, alternatively, to the system on'the suction side of the condensate pump when the float falls, or to the system on the delivery side of the condensate extraction pump, when the float rises, and

hand operable means for eflecting at will abnormal operations of the valve to eflect abnormal operations of the leak off device.

12. A closed boiler feed system comprising a condenser, a condensate extraction pump connected on its suction side to the condenser, a float arranged on the suction side of the condensate extraction. pump and having a water level corresponding to the level on said suction side, a float in said chamber, a pressure operated valve device connected in said closed circuit between the feed pump and the condensate extraction pump, said valve being associated with'the float and adapted to be operated in accordance with the movements of the float, to cause water to be delivered through said "alve, alternatively, to the system on the suction side of the condensate pump when the float falls, or to the system on the delivery side of the condensate extraction pump when the float rises, and hand operable means for actuating said valve device irrespective o the movements of the float. I

13. A closedboiler feed water system comprising a condenser, a condensate extraction pump connected on its suction side to the condenser, a float chamber arranged on the suction side of the condensate extraction pump and having a water level corresponding to the level of condensate on said suction side, afloat in said chamber, a valve casing adjacent the float chamber, ports in said casing, a boiler feed pump, a feed tank, a pipe connection from a port in said valve casing to the closed pipe circuit on the suction side of the feed pump, a connection from a port in said casing to the feed tank, a connection from a port in said casing to the condenser, a pressure operated valve in said casing cooperating with said ports to establish selectively alternative connection between certain of said ports, and a connection between said valve and said float whereby the operations of the valve are cont-rolled in accordance with the movements of said float hand operable means for actuating said float at will irrespective of the level in the float chamber and further hand operable means for actuating said valve irrespective of the movements of said float.

ll. A closed boiler feed system comprising' a condenser, a condensate extraction pump connected on its suction side to the condenser, a float chamber arranged on the suction side of the condensate extraction pump and having a water level corresponding to the level on said suction side, a float in said chamber, a piston valve connected in said closed system between the feed pump and the condensate extraction pump, said valve being associated With the float and adapted to be operated by pressure in ac cordance with the movements of the float to cause water to be delivered through said valve, alternatively, to the condenser when the float falls, or to the system on the delivery side of the condensate extraction pump, when the float rises, hand operable means for actuating the float at will irrespective of the water level in the float chamber and hand operable means for actuating the valve irrespective of the movement of the float.

In testimony whereof, we aflix our signatures.

HARRY FOTHERGILL. HAROLD HILLIER.

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