US2151125A - Boiler feeding apparatus - Google Patents

Description

D. LEWIS March 21, 1939..

BOILER FEEDING APPARATUS Filed May 17, 1937 5 Sheets-Sheet l i In wanton Dartre I A tlfqs.

March 21, 1939.

D. LEWIS 2,151,125 BOILER FEEDING APPARATUS Filed May 17, 1937 5 Sheets-Sheet 2 Invezz tor;

flarcre Lewis, y @c@q l /*5;

D. LEWIS March 21, 1939.

} BOILER FEEDING APPARATUS Filed May 1'7, 1957 5 Sheets-Sheet 3 I72 06% 607; $4 rtrey Lewis March 21, 1939.

D. LEWIS BOILER FEEDING APPARATUS Filed May 17, 1937 5 Sheets-Sheet 4 .Lv mllikl I] II II A a M a Y 4 a Q 5 1 wfi d 4 J w M i 5 w .V J w M 5 a w v 4 x 3 UGO M Jewels;

D. LEWIS 2,151,125

BOILER FEEDING APPARATUS March 21, 1939.

Filed May 17, 1937 5 Sheets-Sheet 5 i Z a a Z3 23 20 2f .A tfys.

Patented Mar. 21, 1939 UNITED STATES PATENT OFF-16E BOILER FEEDING APPARATUS of New Jersey Application May 17, 1937, Serial No. 143,131

6 Claims.

This invention pertains to steam engineering, more especially to improved apparatus for delivering heated feed water to a steam boiler and relates more particularly to automatically actuating valve means operative to determine the admission of live or exhaust steam alternatively to the feed water heater. While in the specific application of the invention, herein chosen for convenience in illustration and description, it is shown as applied to a steam locomotive, it is to be understood that the invention is not in any Way necessarily limited to such specific application but is of broad utility wherever it is desired to deliver water to a steam boiler. However, in order that the functional utility of the novel valve means herein specifically described and claimed may be more fully comprehended it is deemed necessary to describe a complete feed water system of a desirable type in which the novel valve.

means is included and forms an essential part. 7 While it is customary to deliver feed water to steam boilers by means of jet pumps of the kind known as injectors or inspirators, there are certain situations wherein pumps of mechanical type are required, either as auxiliary to or in substitution for such jet pumps, and in particular where it is requisite to preheat the feed water to a high temperature and to deliver the hot Water against a high boiler pressure.

In the patents to Williston et al. No. 1,828,633, dated October 20, 1931, and Allen No. 1,849,900, dated May 15, 1932, desirable forms of apparatus are described, designed economically to preheat feed water to any desired temperature, and to deliver the heated water into the boiler against any desired pressure, the patented apparatus including a multi-stage high-speed turbine-driven centrifugal pump and a water heater of the jet condenser type having nozzles through which the water passes on its Way from the first to the second stage of the pump, and in which it intimately contacts with and condenses exhaust steam from the engine. The heated water is then delivered to the second stage of the pump and by the latter is forced into the boiler.

The apparatus disclosed in the aforesaid patents is highly advantageous as compared with the early types of feed water pump and heater, being compact and relatively light in weight, capable of application wherever it is most convenient to place it,effective to raise the temperature of the feed water through such range as maybe desired and to deliver it against the high boiler pressures of present-day practice, and

1 operating with a high thermal efficiency.

The present invention represents an improvement upon the apparatus disclosed in the aforesaid patents and has for its general object the provision of water heating and feeding means which is dependable under all conditions of engine operation and which will automatically adapt itself to changes in operating conditions, to pro vide apparatus in which exhaust or live steam may be used alternatively for heating the feed water; and to provide automatic valve means of extremely simple and reliable construction operative to control the admission of live or exhaust steam alternatively to the water heater in ac cordance with varying working conditions.

Other objects and advantages of the invention will be made manifest in the following more detailed description and by reference to the accomr panying drawings, wherein Fig. 1 is a fragmentary, diagrammatic side elevation of a locomotive equipped with feed water apparatus embodying the present invention;

Fig. 2 is a vertical transverse section, to larger scale, illustrating a by-pass valve of a desirable type for use as an element of the water heating and feeding mechanism of the present invention;

Fig. 3 is a fragmentary transverse section, to smaller scale than Fig. 2, showing a control valve and feed water heater of improved type desirable for use in the boiler feed mechanism of the present application;

Fig. 4 is an end elevation, partly in vertical section, illustrating the control valve in association with the novel automatic heating valve to which the appended claims are particularly directed;

Fig. 5 is a transverse section, to larger scale, showing the novel heating valve of Fig. 4, but with the parts in a different position;

Fig. 6 is a transverse section showing the control valve of Fig. 3, but to larger scale; and

Fig. '7 is a transverse vertical section illustrating a desirable form of operating and regulating valve useful in the mechanism of the present invention.

Referring to Fig. 1, wherein the invention is shown by way of example as applied to a locomotive, the numeral 1 designates the cab of the locomotive, 2 the tender, 3 the boiler, 4 the turre't valve, 5 one of the steam chests, 6 the correspending cylinder, and l the locomotive stack. From the turret valve 4, which receives live steam from the boiler, a pipe 8 leads to the operating valve 8. The operating valve here il1ustrated is of a type generally resembling the operating valve described in the patent to Walch No. 2,056,698, dated October 6, 1936.

The valve 9 (Fig. 7) comprises a casing l0 having an inlet chamber ii to which live steam is supplied by the pipe 8. The casing has outlet nipples l2 and I 3 to which are connected pipes l4 and I5 leading respectively to the pump actuating turbine and to an automatic water heating valve hereinafter to be described. The flow of steam from the inlet chamber H to the outlet nipples E2 and i3 is primarily controlled by a manually actuable balanced valve member having a main head 16 and a. relatively movable pilot member ll, said pilot member and the valve head being moved one after the other in succession by the manipulation of a lever l8 having a handle which is disposed within the cab.

Preferably the fiow of steam to the respective nipples l2 and I3 is further controlled by a regulating valve comprising spaced heads l9 and 20 which cooperate respectively with annular seats at and 22. The heads I9 and 29 are fixed to a stem 23 which is provided with an actuating handle 23 also located within the cab. Preferably the regulating valve is so devised, as by the provision of a suitable limiting stop, or by properly dimensioning the valve heads relatively to their seats, that, even when closed as much as possible, sufficient steam will be permitted to pass (assuming that the operating valve 56 is 'open) to drive the turbine and pump at a rate at which the pump will still deliver a minimum quantity of Water tothe boiler and also to provide sufiicient live steam, if necessary, to heat the feed Water.

Assuming that'the valve head it is unseated, live steam from the boiler will pass through the pipe l 4 and enter the casing 24 of the pump operating turbine. An exhaust pipe 25 conveys the exhaust steam from the turbine to some convenient point of discharge; for example, as here shown, to the locomotive stack l.

The turbine, which may be of. any desired type, is direct connected to a multi-stage centrifugal pump, preferably provided with four sets of impeller blades mounted on the same shaft and thus always turning at the same speed, such an arrangement, together with the direct connection of the pump to the turbine, saving space and weight and ensuring proper driving without the use of complicated gearing or other inefficient or uncertain connections. A direct connected turbine and multi-stage pump of this general type is more fully illustrated in the patent to Allen No. 1,849,900 above referred to, but whereas in said patented device the pump comprises but two sets of impellers, it is preferred, in accordance with the present invention, toprovide four sets of impellers. However, as in the device of the Allen patent, the first set of impellers constitutes the first distinct stage and, in effect, a separate pump, and this first pump stage delivers feed water to a heater of the jet-condenser type which, in turn, delivers heated water to the first set of impellers of the second stage of. the pump. For convenience in further description, the second, third and fourth sets of impellers are regarded as collectively constituting a second pump stage, although in actual fact the second stage is a three-stage pump in which the pressure of the hot. water is successively boosted up to a point such that it may be delivered directly to the boiler against boiler pressure. Since the details of the pump form no essential part of the present invention, and since its general character is clearly disclosed in the Allen patent, no further specific description is here necessary.

The locomotive tender 2 is provided with the usual Water supply tank from, which the hose connection 25 leads to a strainer 2? from which the cold water sup-ply pipe 28 leads to the intake of the first stage of the pump. The'cold water from the first pump stage is delivered through pipe 2 to the feed water heater 3%.

This feed water heater, which also acts as a con dense-r for exhaust steam, may be located at any desired and convenient point, but is here shown as arranged near the forward end of. the boiler.

The casing of the feed water heater fill may be or any desired external shape, but is here shown as of drum-like form. The interior of this casing (Fig. 3) is divided by septums 3i and 32 into an inlet chamber 33 into which the water is delivered by the pipe 25, an intermediate chamber 34 which receives the steam for heating the water, and a delivery chamber 35. One or more Water delivery nozzles 36, mounted in openings in the septum 3i, deliver the water received from the first pump stage, in the form of powerful jets, into corresponding convergent-divergent ejector tubes 3'! which are mounted in openings in the septum 32 with their receiving ends in the chamber 34 and their delivery ends in the chamber 35. From'the chamber 35 a pipe 35 leads to the inlet eye of the second stage or the pump, and from the delivery orifice of the second stage of the pump a pipe 35 conveys: the hot feed water to the boiler check valve 58 through which it passes into the boiler.

For maximum heating of the feed water, it has been found that certain definite dimensional relations between the nozzles and ejector tubes are requisite. Thus, experimentally, it has been dis covered that by making the diameter of the nozzle throat in a ratio of from one-third to onefifth of the tube throat diameter and by placing the nozzle so that the distance from its throat to that of the tube is from four to five times the tube throat diameter, it is possible to heat. the water to within ten degrees of the theoretical maximum (that'is to say, within ten degrees of the temperature of the saturated steam used in heating it) when the pressure at the discharge of the condenser is kept substantially equal to that of the steam used for heating.

The feed water heater St is designed to raise the feed water delivered to it by the first pump stage to the desired temperature whether the engine is consuming steam or not (in other words, Whether or not exhaust steam is available for heating the water), and to this end the present invention contemplates the provision of automatic means designed to deliver exhaust steam to the heater, so long as such steam is available or, if exhaust steam is not-available, then to supply live steam to the heater but to cut off both exhaust and live steam from the heater when the pumpis not operating, thereby to avoid any possibility of blowing steam back into the tank. The delivery of exhaust or live steam or the cutting off of both is determined by the action of a control valve 38 (Figs. 3 and 6) and a heater valve 39 (Fi s. 4 and 5). I These valves 38 and 39 are conveniently located just forward of the heater 353 (Fig. l), the heater valve 39 receiving live steam from the operating valve 9 through the pipe l5, while valve 33 receives exhaust steam-fromthe exhaust cavities of the valve chest through the pipe 4|.

The control valve 38 (Fig. 6) has a casing 42 divided by a septum 43 into an inlet chamber 44 and a dis-charge chamber 45. Preferably the casing 42 is bolted directly to the casing of the heater 36 so that the discharge chamber 45 is in direct communication with the intermediate chamber 34 of the heater.

The septum 43 has a large opening in which two coaxial valve seat rings 46 and 41 are seated. A valve head 48, cooperates with the seat 46, being mounted on a stem 49 which slides in a fixed guide boss 50 forming a part of the lower head of the casing. The lower end of the stem 49 is furnished with a piston head 5| which slides in a cylinder 52 formed in. a downward extension of the lower head of the casing. One or more compression springs 53 tends to raise the piston and thus to hold the valve disk 48 against its seat 46. The space 54 above the piston head 5| communicates by means of a passage 55 (Fig. 4) with one of the chambers of the heater valve 39 (hereinafter more fully described). Through this passage 55 live steam is at times supplied to the space 54, thereby to drive the piston 5| downward-1y in opposition to the spring'53 and thus to move the valve disk 48 away from its seat.

A check valve disk 56 cooperates with the seat 41, said disk having a tubular stem which slides on a fixed guide boss 51 projecting downwardly from the upper head of the casing. This check valve 56 tends to seat in response to the action of gravity or by fluid pressure applied to its upper side but lifts in response to pressure below it in excess of the pressure above it. When seated, the valve disks 48 and 56 are spaced apart, thereby providing between them a chamber 58 into which leads a passage 59 which communicates with a chamber of the heating valve 39.

The casing 66 of the heating valve 39 (Figs. 4 and 5) may be integral with the casing 42 of the control valve, or separate from and bolted thereto as may be preferred. The casing 60 has a central portion 6| provided with a cylindrical bore in which slides a differential piston valve comprising a stem having a head 63 (Fig. 5) at its lower end and a duplex head of larger diameter adjacent to its upper end, said duplex head comprising the spaced members 64 and 65. The several heads of this piston may be provided with packing rings if desired. As shown, the lower head 63 is of substantially smaller diameter than the upper head members 64, 65,-the cylindrical bore being smaller at its lower end to cooperate with this head 63.

Any suitable ratio of areas between the large and'small ends of this differential piston valve may be employed. For example, if L equals the area of the large head and S equals the area of the small head, and P equals the pressure which acts beneath the large head and P equals the pressure which acts beneath the small head of this differential piston valve, then the forces on this valve are balanced when The casing 66 has an inlet chamber 66 which 75. receives live steam from the operating valve through pipe I5, and the wall of the cylinder 6| has ports at 6'! through which steam from the chamber 66 may enter the space 68 below the valve head 65. The casing also has a chamber 69 which at times communicates by means of a small port 10 with the chamber 68 and which is connected by passage 55 (Fig. 4) with the space 54 above the head of piston 5| of the control valve (Fig. 6) as above described.

The casing 60 also has another chamber 1| which, at times, communicates by means of ports l2 with the space 68 below the piston head 65. Preferably, an orifice ring 13 of predetermined capacity restricts the flow of steam from the outlet chamber II to a predetermined maximum amount. Steam which passes through the ori- (ice I3 flows through the passage 59 (Figs. 4 and 6) in the casing of control valve 36 and thus enters the space 56 between the control valve disks 48 and 56.

A pipe 14 conducts live steam from the steam chest 5 to the space within the cylinder 6| above the valve head 64, so that the latter is always subjected to high steam pressure, so long as the throttle valve is open. The cylinder 6| is provided with stops l5 and 16 at its upper and lower ends, respectively, to limit movement of the differential piston valve. Preferably a drain opening I! is provided beneath the piston head 63 to prevent an accumulation of pressure fluid beneath such head.

Operation When the engine is running and exhausting steam in an amount sufi'icient to heat the feed water, and assuming that the operating valve has been opened to admit live steam through pipes i4 and I5 to the turbine andheater valve respectively, and further assuming that the pressure of live steam from the steam chest, acting on the valve head 64, has pushed the differential valve downwardly until its lower head engages the stop 16, as shown in Fig. 5, live steam is admitted through the ports 61 to the chamber 68 and thence through the port 10 to the space 69 from which it flows through the passage 55 into the space 54 above the piston 5| of the control valve, thus pushing said piston downwardly and moving the control valve disk 48 away from its seat. At this time the head 65 of the heater valve piston cuts off communication between the chambers 68 and "H so that no live steam can enter the latter chamber. However, chamber 44 of the control valve is now supplied with exhaust steam from the exhaust cavities of the steam chest, and this steam passes between the lowered valve disk 48 and its seat and enters the space 58 and lifts the check valve disk 56 from its seat. The exhaust steam then passes through the chamber 45 and into the intermediate chamber 540i the heater device.

At the same time, live steam admitted through the pipe l4 starts the turbine and thus drives the pump, the speed of the turbine and pump being determined by the amount of steam admitted, which is regulated by the setting of the regulating valve comprising the heads l9 and 26. Upon admission of exhaust steam to the chamber 34 of the heater, its first eiiect is to tend to clear the chamber of water by forcing it through the pipe 35 into the second pump stage. By this time thepump has picked up speed sufficient to draw water from the tank and to deliver it at substantially tank temperature and at a pressure of the order of fifty pounds per square inch, for

-it acts as a relief or safty valve for heating the water.

examplato the nozzles 36 of the water heater; From these nozzles the water is delivered in high velocity jets into the convergent combining sections of the ejector nozzles 37. These jets of relatively cold Water entrain the exhaust steam by anejector' action, condensing the steam, and thereby very efiectively heating the water, some of the heat energy of the steam being converted into pressure as the water and condensate pass out through the divergent delivery ends of the tubes into the chamber 35. From this chamber the water, now heated, for example to a temperature nearly approximating'the temperature of the saturated steam admitted to' chamber 34, enters the intake eye of the second pump stage. In passing through this second pump stage, the pressure of the hot water is raised sufficiently to'force it through the check valve 40 into the boiler.

So long as the engine continues to supply exhaust steam and'so long as the exhaust valve remains open to supply steam for actuating the pump, the above operation continues.

If, when the engine is running and delivering exhaust steam, the operating valve be closed so as to stop the pump, the supply of steam through both pipes I4 and i5 is simultaneously cut off. Since live steam is now no longer available to act on the piston 54 of the control valve, the spring 53 raises the piston 54 and closes the valve disk 48 against its seat, thus cutting off communication between the condenser and the exhaust cavities of the engine. However, since valve disk 48 is held to its seat by spring pressure, in response to any accidental excess pressure which might develop in chamber 58. It is to be noted that at this time steam from the steam chest is still available to act on the upper head 64 of the heater'valve, thus holding the differential piston valve down in the position of Fig. 5. As soon as the valve disk 48 is seated, the check valve 56 returns to its seat and so prevents feed water from flowing into the control valve chamber 58 and thence into the passage 59. The parts thus remain until the pump is restarted or the engine ceases to deliver exhaust steam.

It is frequently necessary to feed water to the boiler when the engine is not running or at least is not consuming steam (as, for example, when a locomotive is drifting) but, as above pointed out, it is highly undesirable to deliver cold water to a hot boiler, although under the conditions just referred to, no exhaust steam is available However, in accordance with the present invention, and by the'automatic operation of the appliances above described, the failure of the exhaust steam supply, While the operating valve is open, immediately results in the delivery of live steam to the water heater in sufiicient quantity to heat the feed water. Thus, let it be assumed, that the operating valve is open so that live steam is being delivered to the turbine, and is also free to pass through the pipe I 5 to the chamber 66. However, at this time live steam is no longer supplied by the pipe 74 to act on the upper head 64 of the differential valve as the throttle is now closed. Thus unbalanced steam pressure in the space 68 reacts against the lower side of the head 65 of the difierential valve and raises this valve to the position shown in Fig. 4. In this position the lower. head 63 closes the port 10, while at the same time the space 68 is put into communication with means of ports 12 the chamber H by water in accordance Live steam now flows through the pipe I 5, chamber 68, and the ports l2 into the chamber 1l,'and through passage 59 into the space betweenthe'valve disks 48 and 56 of the control valve. The valve 48 is now closed by the spring 53 (since steam is cut oif from the chamber 54 by the valve head 63), but the check valve 56 is lifted by the live steam in the chamber 58- which is now free to flow into the chamber 34 of the heater where it is entrained by the water jets and heats the water in the same way as the exhaust steam as above described. 7

By suitably designing the heads l9 and 26 of the regulating valve, it is possible to provide suitable amounts of live steam for heating the with the amount of water being pumped. For instance; with the pump operating at capacity, sufiicient live steam may be provided to raise the water temperature through at 50% capacity, suflioient steam may be provided to raise the water through 80; and at 25% capacity, sufiicient steam may be admitted to raise the water through 60, etc. Obviously other proportions may be provided for. by suitably relating the i9 and 20 and the orifices with which they cooperate. As already noted, it is preferred to make the valve heads l9 and 20 of such size relatively to the passages through the valve seats as to ensure turbine driving steam sufficient to create a delivery pressure such as to force some water into the boiler so long as the operating valve is open.

As soon as the throttle is opened to admit steamto the steam chest and cylinder to start the engine, pressure is applied to the upper end of the difierential valve 64, thus forcing the latter valve down and reopening port 76 while cutting off the passage of live steam to the chamber 1!, and at the same time readmitting exhaust steam to the chamber 4| of the control valve.

While the apparatus as above described is operative for the intended purpose and without adjunctive'features, it is preferred to provide an automatic pressure equalizer for the delivery chamber 35 of the'heater'in order to ensure optimum conditions of operation at all capacities of the pump.

If the pump be considered separate pumps, zles of the heater and the second of which delivas consisting of two ers to the boiler, it will be clear that the second pump delivers against a substantially constant head; that is to say, the boiler pressure, but receives its supply from a source of pressurewhich may vary in accordance with the speed of the first pump. On the other hand, the first receives its supply at a substantially constant head but delivers into a heater in which the pressure may vary substantially in accordance with the speed of the second pump.

Moreover, since the pump is of the centrifugal type, there is a definite minimum speed at which amount withdrawn from the heater by the second,

stage of the pump for delivery to the boiler.

However, since the impellers of both the first.

sizes of the valve heads one of which delivers to the nozis merely churned by the impeller blades and re-- combined with the and second stages of the pump are mounted on the same shaft and necessarily turn at the same speed, any reduction in the speed of the second stage, for cutting down the supply to the boiler, results in a similar reduction in speed of the first stage.

To obtain a clear conception of what happens when the speed of the pump is reduced, it is convenient to consider that extreme condition which exists when the speed is reduced just to the point at which the second stage of the pump will no longer deliver any water to the boiler. Manifestly, when this condition obtains, the first pump stage continues to discharge water into the heater, although at a lesser rate, and since no water is now withdrawnfro-m the heater by the second pump stage, pressure rapidly builds up in the delivery chamber 35 of the heater. As one result of this condition, the entire heater and the passages leading to it soon fill with water so that no-further condensation can take place.

As a matter of fact, the amount of boiler pressure against which a jet-condensing heater of the type above described will operate is very strictly limited. Moreover, within the range of pressures ,within which such a jet-condensing heater will actually operate without choking, the amount of steam condensed rapidly grows less as the back pressure in the delivery chamber in the heater increases, and although in theory the building up of a high back pressure at the inlet eye of the second pump stage (at low speeds) will tend eventually to equalize the output of the first and second stages of the pump, the choking of the condenser constitutes the real limit which determines the minimum practical speed of operation.

On the other hand, while excessive back pressure at the intake eye of the second pump stage is not permissible, insufficient back pressure at this point is also undesirable since at the high temperature of the feed water, low pressure results in foaming and cavitation, with loss of pump capacity and efiiciency. Preferably the back pressure at the inlet of the second pump stage should be in excess of the boiling pressure corresponding to the water temperature, and when using a jet-condenser heater designed as above described, this temperature is approximately within ten degrees of the temperature of saturated steam at the pressure supplied to the heater for heating the water.

Accordingly, it is highly desirable to provide automatic means for maintaining a predetermined pressure in the delivery chamber 35 of the heater. To this end, the present invention contemplates the provision of an automatic bypass valve operating to relieve the pressure in the delivery chamber 35 whenever, during the operation of the pump, it tends to rise excessively.

One desirable form of by-pass valve is shown at" in Figs. 1 and 2. This valve is conveniently located adjacent to the pump and is here illustrated as mounted directly upon the pump casing, although this is not necessary. This by-pass valve comprises a. casing 19, the interior of which is divided by a septum 80 into an inlet chamber 8| and an outlet chamber 82. The inlet chamber BI is always in communication by means of pipe .35 with the delivery chamber 35 of the heater, preferably communicating with pipe 38 just where the latter enters the inlet of the second stage of the pump. The outlet chamber 82' is connected by means of a pipe 83 and a hose connection 84 to the water tank in the tender. The septum 80 of'valve casing 19 has an opening for the reception of a cylindrical guide 85 whose upper edge constitutes an annular valve seat with which .cooperates a by-pass check valve 86. This check valve has guide wings which slide in the guide 85, and the valve also preferably has an upstanding central boss 8? for engagement by the lower end of a loading piston 88 which slides in a bore in a hollow plug 39 forming the top of the casing l9. Above the piston 88 is a space 92: which communicates by means of a pipe ill with the chamber 58 between the Valve disks t3 and 56 of the control valve 38, the pipe entering said chamber at Ql Normally, the valve 85 is held to its seat by the Weight of piston 88, assisted by the fiuid pressure in the space 99, but

in response to excess pressure at the intake of the second pump stage, the valve 86 rises and. allow; water to escape from the chamber 35 through the pipe 35 and thence through the chambers 8i and 82 and the pipe 83 to the tank in the tender.

By drawing the steam which applies pressure to the piston 88 from the chamber 53 of the control valve, it is assured that the pressure in the chamber Q8 will never exceed that of the steam supplied for heating. At times, due to improper operation of the heater, the pressure in the intermediate chamber 35 of the heater may be higher than that of the heating steam, but the check valve disk 56, which is interposed between the chamber 3 and the inlet 9H to the pipe 9!, efiectively prevents any higher pressure than that of the heating steam from acting on the piston 89. Normally the heating steam has a pressure which may vary from zero to twenty-five pounds per square inch, it being noted that even when live steam is being used for water heating, such steam is so throttled in passing through the various pipes and valves and through the orifice 73 that when it reaches the chamber 58, its pressure is not substantially higher than that of the exhaust steam which is used under other conditions.

If the piston 88 and the valve 86 be of the same eifective diameter, the check valve 86 would, in theory, open as soon as the pressure in chamber 8! even slightly exceeds the pressure of the heating steam. Since there is some drop in pressure between the chamber 35 of the heater and the chamber 8! of the Icy-pass valve, it may be desirable, in order to maintain the pressure in the heating chamber 35 equal to that of the heating steam used, to provide a spring 32 to react with a predetermined upward pressure on the valve 85 so as to compensate for the pressure drop between the chambers 38 and 85. This spring may, for example, be so arranged as to exert a pressure corresponding to a pressure of from one to five pounds per square inch acting over the effective area of the valve 86.

While the check valve disk 56 of the control valve device forms a convenient check to prevent excessive pressure from entering the chamber 9!], any other check valve appropriately arranged may be employed in so far as maintenance of uniform pressure in the by-pass valve chamber 90 is concerned.

While, as shown, the spring 92 is a compression spring disposed beneath the valve disk 86, it may, as well, be a tension spring arranged to act upwardly on the piston 88. In fact, this latter arrangement has certain advantages; for example, it leaves the valve 86 always free to seat in response to any tendency whatever of fluid to flow in reverse direction from the chamber 82 to the chamber 8|.

Preferably a pressure gauge 94 and a thermometer device 95 are disposed within the cab and connected to the delivery pipe 35* of the heater so as to inform the engineer, at all times, of the pressure and temperature conditions of the feed Water when the pump is in operation.

While a certain desirable embodiment of the invention has herein been shown and described by Way of example it is to be understood that the invention is not necessarily limited to the precise arrangement herein illustrated but is to be regarded as of broad scope and as inclusive of any and all equivalents.

I claim:

1. Automatic valve means for determining the alternative admission of live or exhaust steam to a water heater forming part of a locomotive boiler feed system which includes a steam driven pump having a steam supply conduit and which also includes an exhaust steam conduit having therein a motor actuated control-valve, characterized in having a casing provided with a chamber and a differential piston-valve sliding in said chamber, said valve including a stem and spaced heads of relatively difierent diameters fixedly secured to opposite ends of the stem, the casing having an inlet for pump-actuating steam always communicating with the space between said heads and also having two spaced delivery orifices 50 related to the heads of the piston valve that when one orifice is open the other is closed, said orifices, when open, being operative respectively to admit steam from the casing to the heater and to the exhaust control-valve motor respectively, and means operative to admit engine operating steam to act upon the outer face of the larger head of the differential piston only when the engine is running, thereby to move the piston valve into one end of said chamber.

2. Automatic valve means for determining alternative admission of live or exhaust steam to a water heater forming part of a locomotive boiler feed system which includes a steam driven pump having a steam supply conduit and which also includes an exhaust steam conduit having therein a motor actuated control-valve, characterized in that said valve means includes an elongate casing having therein a chamber including cylindrical portions of different diameters, a differential piston including relatively fixed spaced heads arranged to slide respectively in said cylindrical portions of the chamber, the chamber having an admission port in its wall through which steam from the pump supply is admitted, the chamber also having delivery orifices in its wall leading to the heater and to the exhaust control-valve motor respectively and having a steam inlet at that end which is of larger diameter operative to admit engine operating steam only so long as the engine is running, the relative areas of the heads of the piston valve being such that, when engine operating steam is available, the piston valve occupies one end of the chamber and opens the orifice leading to the exhaust valve motor, and when engine operating steam is not available it occupies the other end of the chamber and opens the orifice leading to the heater.

3. Automatic valve means for determining alternative admission of live or exhaust steam to a water heater forming part of a locomotive boiler feed system which includes a steam driven pump having a steam supply conduit and which also includes an exhaust steam conduit having therein a motor actuatedcontrol-valve, said valve means comprising a casing having a steam inlet chamber communicating at all times with the a supply conduit, outlet orifices which, when open, are operative respectively to admit steam from the casing to the heater and to the control-valve motor respectively, and having an inlet supplied with steam only so long as the engine is running,

characterized in having a single movable valve device so constructed and arranged as to be differentially responsive to the pressure of steam from the pump-supply conduit and to thepressure of steam used for running the engine, respectively,

said valve comprising orifice closing elements operative, in accordance with the position of said valve in the casing, to close one of said orifices and concomitantly to open the other respectively.

4. Automatic valve means for determining alternative admission of live or exhaust steam to a Water heater forming part of a locomotive boiler feed system which includes a steam driven pump having a steam supply conduit and which also includes an exhaust steam conduit having therein a motor actuated control-valve, said valve means comprising a casing having a steam inlet chamber communicating at all times with the pump supply conduit, outlet orificeswhich, when open,

are operative respectively to admit steam from the casing to the heater and to the control-valve motor respectively, and having an inlet which is supplied with steam under pressure only so long as the engine is running, characterized in having a unitary piston valve slidable within the casing and comprising spaced relatively fixed heads of difierent diameters respectively, said heads being so spaced that in one position of the valveone head closes one of the outlet orifices and in another position of the valve the other head closes the other orifice, the space between the heads communicating with the pump supply conduit and the outer surface of the larger head being exposed to engine operating steam when the engine is running.

5. Automatic valve means for determining alternative admission of live or exhaust steam to a water heater forming part of a locomotive boiler feed system which includes a steam driven pump having asteam-supply conduit and which also includes an exhaust-steam conduit having therein a motor actuated control-valve, said valve means comprising a casing having a steam inlet chamber communicating at all times with the pump supply conduit, outlet orifices which, when open, are

operative respectively to admit steam to the heater and to the control-valve means respectively, and having an inlet supplied with steam under pressure only so long as the engine is running,

characterized in having a unitary piston-valve" slidable within the casing and comprising relatively fixed spaced heads of different diameters respectively, the space between said heads communicating with the pump-supply conduit and the outer surface of thelarger head being exposed to engine operating steam only so long as the engine is running, the areas L and S of the large and small heads respectively being such that havinga steam supply conduit and which ,alsolincludes an exhaust steam conduit having therein a motor actuated control valve, characterized in having a casing including a cylindrical portion closed at its opposite ends and defining an elongate chamber, said chamber being of smaller diameter at one end than elsewhere, a differential piston-valve arranged within said chamber, the piston-valve having a large head within the larger part of the chamber and a small head arranged to slide in the smaller part of the chamber, the casing comprising an inlet cavity designed to receive pump actuating steam and an inlet port leading from said inlet cavity into the space between the large and small heads of the piston- 5 valve, the casing also having an outlet cavity provided with a port leading from the part of the chamber in which the larger piston head slides, the casing having a second outlet port leading from the part of said chamber in which the smaller head of the piston-valve slides, and the casing also having an inlet port leading into the end of the chamber in which the larger piston head slides, said latter port being designed to admit engine operating steam so long as the engine is running, and the outlet ports providing communication between the chamber in the casing and the heater and the exhaust valve motor respectively, in accordance with the position of the piston-valve in the chamber.

DAR'I'REY LEWIS.

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