US2264753A - Pump control valve - Google Patents

Description

Dec. 2, 1941. E. HENKEL PUMP CONTROL VALVE Filed Feb. 26. 1941 FROM Pl/MP DEL/VERY PUMP [XII/W57 INVENTOR. Elem/1 HEM/(EL F190! PUM DEL/VERY Patented Dec. 2, 1941 PUMP CONTROL VALVE Erich,Henkel, Calumet City, 111., assignor to The Superheatcr Company, New York, N. Y.

Application February 26, 1941, Serial No. 3801355 4 Claims.

The present invention relates to pump control devices and particularly to improvements in control valves for preventing overspeeding of a centrifugal pump.

Centrifugal pumps such as are employed for feeding water to locomotive boilers are provided with mechanical governors arranged to shut off steam to the turbine drivin the pump in the event that conditions arise which cause it to overspeed. However, in the operation of feed Water pumps on locomotives, conditions may arise causing the governor to trip frequently, thus causing repeated operation and wear of the tripping mechanism. For the purpose of avoiding undue wear of tripping mechanisms of pumps of this type in order that they may be in good condition to become effective should dangerous overspeeding occur, various types of control valves automatically responsive to conditions, other than speed, which serve to indicate the state of operation of the pump have been devised. Improved valves of this type are disclosed in the copending application filed in the name of Joseph F. Grifiin on February 23, 1940, under serial No. 320,329. The present invention contemplates a further improvement in control valves of this type. The improvement is particularly designed to prevent overspeeding of the pump as a result of supplying steam in excessive amounts or at excessively high pressures at times when there is no load on the pump, as for example when both the suction and delivery lines of the pump are dry.

The invention will be best understood upon consideration of the following detailed description of an illustrative embodiment thereof when read in conjunction with the accompanying drawing in which: I

Figure 1 is a diagrammatic view of parts of a pump system embodying the control valve of the present invention; and

Figure 2 is an enlarged view partly in section to show the detailed construction oi the control valves that prevent over-speeding of the pump.

In Figure 1 the numeral l designates a turbine driven centrifugal pump drawing water as from a locomotive tender through a suction line H and supplying it to the boiler through a pipe l2 leading to the boiler check valve. The pump II) is operated by steam supplied through a pipe I! subject to the control of a throttle valve l5 and a hydraulic responsive control valve which is designated as a whole by the numeral I6.

The control valve l6 comprises a housing 20 having therein a valve member 2| provided with a pair of valve disks 22 connected to a stem 23 that projects through the bottom 24 of the housing. Mounted on the underside of the Valve casing 20 concentric with valve stem 23 is a piston cylinder 3|! formed with a chamber 3|. In cylinder 30 is a piston 80 subjected at its upper end to the pressure of steam reaching the chamber 3| from the valve inlet 26 through a passage 33 of a relatively small area. The piston is also subjected on its under side to the delivery pressure of pump ||l conveyed to the chamber 35 through a pipe connected to the water delivery line I2, as shown in Fig. 1. A vent 63 in the wall of the upper chamber Si is so located that when valve 2| is closed, steam is bled from the chamber 3| and its pressure cannot act to prevent the opening of the valve by pump delivery pressure acting on the under side of piston Ell. As piston 60" ascends to open valve 2|, it obscures the vent port 63 so that the steam pressure is built up in the chamber at the upper face of the piston and acts if delivery pressure iails to automatically close valve 2|. A by-pass 25 is connected to the steam line l4 adjacent the inlet 26 and outlet 21 of valve l6. Chokes in the by-pass permit only a limited amount of steam for starting the pump slowly to flow to the turbine of pump ||l whenever the throttle valve I5 is opened although the control valve 2| may still be closed.

The hydraulic control valve described above is identical with one of the forms described in the Griflln application in all respects except that herein the pipe 25 by-pass'es the valve IB whereas in the application a small orifice is formed in the wall that separates the inlet'26 and outlet 21 of the valve. The reference numorals used above correspond to those employed in the patent.

In accordance with the present invention a pressure relief valve designated as a whole by the numeral 10 is connected into the by-pass' 25, as for example between the chokes 1| and 12. This relief valve prevents the pressure of steam flowing through the b-y-pass to the pump exceeding a predetermined value upon the opening of throttle valve l5, regardless of the degree of opening of the latter. The relief valve 1|) comprises a valve disk 13 held against its seat by a spring 14 to close olf the vent line 15 from the by-pass 25, the spring being selected and arranged to hold the valve 13 closed until a predetermined steam pressure is reached in the bypass 25. When valve 10 opens, steam is vented off through a line 16 so as to relieve the pressure in the by-pass. The valve 13 is operatively connected to a piston 11 subjected to the pump delivery pressure through a conduit 18. A spring 80 is arranged to oppose delivery pressure acting on piston 11 so that the valve 13 does not close, if it has opened, until a predetermined pump delivery pressure is attained.

When the throttle valve I is opened steam flows through the byrpass 25 and the chokes H and 12 tend to limit the pressure and amount of steam to value suitable for starting of the pump and operating it slowly. However, if the pump happened to be without load as a result, for example, of both its suction and delivery lines being dry, even a relatively small quantity of steam passing through the by-pass might cause it to overspeed. To avoid this, the relief valve acts whenever the pressure in the by-pass 25 exceeds a predetermined selected safe value to vent part of the steam from the by-pass through the line 16 so that under all conditions a safe pressure is maintained at the inlet of the turbine that drives the pump. If, however, the pump is operating under normal conditions it slowly builds up water delivery pressure. When a predetermined delivery pressure is reached it acts on piston 11 to move it downwardly so as to close the valve 13, or hold it to its seat if it has not opened. Closing of the relief valve permits the steam pressure reaching the pump through the by-pass to increase, thus speeding up the pump. When the pump operates at a predetermined water delivery pressure, which need not necessarily be the same as that controlling the valve 13, the delivery pressure communicated to the under side of piston 60 acts to raise the latter. This results in opening the control valve 2| so that the pump may speed up and further increase the delivery pressure to the value required to feed the boiler. As valve 2| opens piston 60 obscures the vent 63 so that steam pressure corresponding to that at the inlet 26 of the valve 2| is built up in the chamber 3|. Thereafter if the water delivery pressure should fall below said predetermined value, the pressure of steam in the chamber 3| acts on the upper face of piston 60 to close the valve 2|, thus slowing down the pump to the rate of operation permitted by the amount of steam flowing through the Icy-pass 25.

What I claim is:

1. In a pump control system having a conduit for supplying steam to the pump, a control valve in said conduit arranged to open when the pump delivery pressure reaches a predetermined value and to close when said pressure falls below said value, and a by-pass around said control valve for permitting a limited amount of steam to flow to said pump for operating the latter slowly when said control valve is closed; a relief valve associated with said by-pass for preventing the pressure of steam flowing through said by-pass to said pump exceeding a predetermined value; and means responsive to a predetermined pump delivery pressure operatively connected to said relief valve so as to render it ineffective when said last delivery pressure is attained.

2. In a pump control system having first a throttle valve and then a control valve in series in a conduit supplying steam to the pump, a restricted by-pass around said control valve for passing a limited amount of steam to the pump when said throttle valve is open though said control valve is closed, means responsive to a predetermined pump delivery pressure operative to open said control valve, and means for closing said control valve when the pump delivery pressure falls below said predetermined value; a relief valve associated with said by-pass for preventing the pressure of steam flowing therethrough to the pump exceeding a predetermined value on opening of said throttle valve to start the pump; and means operatively connected to said relief valve and responsive to a predetermined delivery pressure for rendering said relief valve ineffective when said last pressure is attained.

3. In a pump control system having a control valve in a conduit supplying steam to the pump, a by-pass around said control valve for passing a limited amount of steam to the pump when said throttle valve is open though said control valve is closed, means responsive to a predetermined pump delivery pressure operative to open said control valve, and means for closing said control valve when the pump delivery pressure falls below said predetermined value; a relief valve associated with said by-pass for preventing the pressure of steam flowing therethrough exceeding a predetermined value on opening of said throttle valve to start the pump; and means operatively connected to said relief valve and responsive to a predetermined delivery pressure for rendering said relief valve inefiective when said pressure is attained.

4. In a pump control system having first a throttle valve and then a control valve in series in a conduit supplying steam to the pump; a bypass comprising a pipe connected to said conduit at both sides of said control valve; means in said by-pass for restricting the amount of steam flowing through the latter to said pump so as to permit only a relatively small amount of fluid to flow to said pump when said control valve is closed; means responsive to a predetermined pump delivery pressure operative to open said control valve; and means for closing said control valve when the pump delivery pressure falls below said predetermined value; a pressure relief valve connected to said by-pass for maintaining steam pressure therein below a predetermined value; and means responsive to a predetermined delivery pressure of the pump operativ'ely connected to said relief valve so as to render it ineffective when said delivery pressure is attained for permitting increase of the pressure of actuating fluid flowing through said by-pass to said pump.

ERICH HENKEL.

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