US2661014A - Automatic blow-down valve - Google Patents

Description

AUTOMATIC BLOW-DOWN VALVE Filed May 25, 1950 Patented Dec. 1, 1953 AUTOMATIC BLOW-DOWN VALVE William Brankley Limited Hollingbery, England, assignor to Houseman Whitley Bay & Thompson Application May 23, 1950, Serial No. 163,627

2 Claims. (CL 137-244) This invention consists in an improved automatic blow-down valve for use on steam engines, and more particularly steam locomotives, the blow-down valve being of the kind wherein means are provided whereby on the operation of the steam. control valve the blow-down valve is operated by means of the steam pressure of the boiler on a piston connected with the valve proper, so that when the engine is in operation, the blow-down valve is open and there is a discharge of sludge-laden water and/or water containing dissolved solids in concentration from a sludge inlet in the valve chamber, while when the engine is not in operation the valve is closed and such discharge ceases, a clearing needle being formed on the valve proper so that when the latter closes the said needle passes into the valve discharge orifice to clear the latter of sludge.

The object of the invention is to provide an automatic blow-down valve of the kind referred to wherein means are provided for creating the optimum conditions for discouraging the lodgement of' particles of sludge. Another object is to combine with such a valve means for preventing wastage of the steam which effects the opening and closing of the valve.

The blow-down valve according to the invention comprises a casing, a fiuid operated valve in a bore in said casing, said valve being adapted to control a valve discharge orifice in said casing, a steam cylinder above said valve casing, the lower portion of said cylinder being adapted to be connected to the engine throttle, a piston in said cylinder, a sludge inlet in said casing, said sludge inlet being arranged at an acute angle to and communicating with the casing bore so as to be inclined in the direction of fiow of the sludge-laden water said valve comprising a valve rod whose upper end is connected to said piston, a valve head at the lower end of said valve rod, a valve seating in said valve casing with which said valve head is adapted to seat, a spring adapted normally to maintain said valve against said seating, said seating being separate :from said valve discharge orifice, a tapering clearing needle projecting axially from said valve 'head, a constriction member having formed therein a central converging constriction orifice, said clearing needle being adapted to project through said converging constriction orifice when said valve is closed, the distance of said valve seating from said sludge inlet port being such that said port is not fully uncovered until said valve is fully opened.

The invention will now be described by way of example with reference to the accompanying drawing which shows in sectional elevation a locomotive blow-down valve.

Referring more particularly to the drawing the 2 chamber body I provided with a sludge inlet 2 which may be fitted with any suitable form'of coupling 3 for connecting it to the selected take ofi point on the boiler (not shown), either through a header serving as collector to several internal pipes, or otherwise in any convenient manner. The sludge inlet 2 is arranged at an acute angle to the valve chamber i so as to ofl'er the minimum resistance to the passage of the sludge into the valve chamber.

A valve insert 4 of monel metal or other suitable material is provided to give a close fit in and co-axial with the bore of the valve chamber I, the bore of the sludge inlet 2 passing through the said insert to join the continuation of the valve chamber bore at a port 401.. At the lower end of the insert there is a. constriction disc 5 alsoof monel metal which has a funnel shaped orifice 5a which converges in the direction of flow of the sludge-laden water with a view to promoting the free passage of sludge particles, and whose size is calibrated to give the required flow. 'I'he'constriction disc 5 is removable so that it can be readily exchanged for one having an orifice of greater or less diam-'- eter, so that a greater or less flow of water may be obtained as desired. At a distance above the constriction disc 5 there is formed in the insert 4 a valve seating 4b.

A valve rod 6 of monel metal passes through an ordinary stuffing box 1 on the valve body 3, and has a beveled valve head 6a and a tapered needle 6b formed at its lower end, the former being adapted to seat on the valve seating 4b, and the latter to project through the orifice 5a when the valve 6a isin its lowermost position, so that each time the valve closes, the needle 6b clears the orifice 5a from possible scale or sludge lodgements.

At the upper end of the piston rod 6 there is fitted a smooth piston 8 working in a steam cylinder 9 rigidly secured to the valve body I.

' A connecting pipe l0 leads from a .small steam a paratus comprises a lon itudinal y bored valve space 9a provided at the underside of the piston, to the steam chest of the locomotive. Hence, when the steam pressure rises in the locomotive steam chest, a similar pressure is built up under the piston 8, tending to force it upwards, and thus opening the valve.

Normally the valve 6a is held in the closed position by a spring I l in the upper portion of the steam cylinder 9 exerting a downward pressure upon the upper side of the piston 8, the said spring at its upper end abutting against the inner face of a flanged disc or-cover plate l2 se-' cured to the upper end of the cylinder 9. The

strength of this spring is calibrated to provide the requisite closing pressureaccording to the particular conditions, boiler pressure and so forth. Hence, when steam is admitted to-the small steam space 9a, the piston' 8 is forced upwards against the pressure of the spring I I, which at once closes the valve 6a immediately the steam pressure 'is released.

In order to prevent air locking in the upper part of the steam cylinder 9 an air vent I3 is provided in the cover plate l2. The said air vent leads to a bore I2a in a downwardly extending central boss 12b the lower extremity of which bore terminates in a valve seat 120. The upper portion of the piston rod 6 slightly projects beyond the piston 8, and terminates in a valve head 60 which, when the piston'8 is atthe'upper limit of its stroke, registers with the seat 120 formed in the boss 12b, thus closing the vent valve.

:Should a'pressure tend to build up on the upper side of the piston 8 due to leaka e past the rings or other packing thereon, the vent valve 60 will be eased from its seat 120 just sufficiently to vent that pressure, an equilibrium position being established by the steam pressure acting upwards, the spring .II and leaking pressure acting downwards.

' It is necessary to provide for the closing of the vent as above described, for the reason that owing to the wear and tear on the piston rings there could be steam passing from the under to the upper side of the piston. Hence, if the air vent we're not closed there would be a blow of steam to atmosphere which could detract from the operating pressure of the steam on the under side of the piston.

In operation, the action is as follows:

Assume the locomotive is standing with steam up prior to commencing a run. The regulator is closed, therefore no steam is admitted to the steam chest. Consequently no steam can enter the small steam space 9a which is connected to the steam chest. The valve to is therefore closed and held so by the pressure of the spring I I.

When the driver opens the regulator, admitting steam to the steam chest a pressure on the underside of the piston 8 forces the piston upwards against the pressure of the spring H thus lifting the valve Go away from its seat '41), any air entrapped in the upper portion of the steam cylinder being forced out through the vent l3.

In a preferred form of the invention the travel of the valve to is about one and a quarter inches, but the distance from the seat 4b to the lowest edge of the sludge inlet port 4a in the valve insert is about three quarters of one inch, so that the sludge cannot commence to flow, until the valve has passed this point. This means that the valve is well away from its seat before the sludge can commence to flow, so that all wire drawing across the face of the valve is eliminated.

When the steam is shut off from the locomotive as described, the valve 6a closes by the pressure of the spring I l, with considerable force, and the clearing needle 6b is pushed through the outlet orifice 5a.

With the blow-down apparatus according to the invention complete control is obtained both of sludge and dissolved solids content even if the sludge particles be relatively large. Again, the valve is self clearing and non-chokeable.

1 Yet again, the forces necessary to operate the valve are provided by the steam pressure in the locomotive steam chest, and need only be sufficient to overcome the combined downward force of the spring 1 I, plus the friction force set up by the side thrust of the blow-down pressure against the spindle. No direct closing pressure is exerted.

by the pressure in the boiler. Further, the intermittent opening and closing of the valve brought about by the operation .of the. locomotive regulator sets up suflicient turbulence inthe boiler water adjacent to the sludge inlet 2 to the valve ib, to keep the sludge stirred up, thus preventing packing in the narrow water spaces.

The invention, by suitable adaptation, may be applied to stationary boilers in addition to locomotive boilers.

I claim:

1. A. blow-down valve of the kind referred to comprising a casing, a fluid operated valve in a bore in said casing, said valve being adapted to control a valve discharge orifice in said casing, a steam cylinder above said valve casing, the lower portion of said cylinder having a pressure fluid port therein, a piston in said cylinder, a sludge inlet in said casing, said sludge inlet being arranged at an acute angle to and communi eating with the casing bore so as to be inclined in the direction of flow of sludge-laden water, said valve comprising a valve rod whose upper end is connected to said piston, a valve face at the lower end of said valve rod, a valve seating in said valve casing bore on which said valve face is adapted to seat, a spring adapted normally to maintain said valve face against said seating, said seating being separate from said valve discharge crifice, a tapering clearing needle projecting axially from said valve face, a constriction member having formed therein a central converging constriction orifice in coaxial alinement with said seating, said clearing needle being adapted to project through said converging constriction orifice when said valve is closed, the distance of said valve 'seating'from said sludge inlet port being such that said port is not fully uncovered until said valve is fully opened, said valve casing being coaxially recessed at its lower and said seating comprising a coaxially bored and ported insert having a close'fit in said. recess to form a continuation of the bore of said casing, the port of said insert forming a coaxial continuation of said sludge inlet port, said constriction member consisting of a removable disc positioned at the lower end of the insert, the orifice of said disc being calibrated to give the required flow, a cover plate at the head of said cylinder, an axially bored boss on said cover plate comprising an air vent communicating with said steam cylinder, a valve seating at the lower of the bore of .said boss and a valve member 1' id with said piston, saidvalve member being adapted to seat against said vent valve seating when said piston is at the upper limit of its stroke.

2. A blow-down valve according to claim 1. wherein the valve rod projects above the piston, and said vent valve member is formed on the projecting end of said valve rod, said vent valve member being adapted to seat against said vent valve seating when said piston is at the upper limit of its stroke.

WILLIAM BRANKLEY HOLLINGBERY.

References Cited in the file of this patent UNITED STATES PATENTS Number

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