Valve Systems

Abstract

A valve system for a liquid-containing vessel such as a boiler in which a valve chamber between connections leading to the vessel, to a control device and to exhaust contains a valve head which can close the connections to the vessel and to exhaust but can not close the connections to the control device.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to equipment comprising, in combination, a vessel for containing a liquid, a pipe connecting said vessel to a device for controlling the supply of liquid to said vessel to maintain the liquid in the vessel at a substantially constant level and a valve located in the pipe between the vessel and the control device, which valve is arranged to control the flow of liquid between the control device and the vessel and between both the control device and the vessel and exhaust.

The present invention has particular application to equipment of the above kind in which the vessel is a steam boiler and the valve in the pipe between the boiler and the control device is operable for the removal of sediment or other solid impurities from the pipe.

2. Description of the Prior Art

In a known arrangement in which there is a connection between the top of the boiler and the top of the control device whereby the pressure in the control device is the same as that in the boiler, the valve is arranged so that, during normal operating conditions, the control device and the boiler are in communication with each other whereas, when it is desired to remove the sediment or other impurities, the valve is operated so as to connect the control device to exhaust whereby impurities in the pipe between the valve and the control device are blown out of the pipe and the valve is also operated to connect the interior of the boiler to exhaust to blow out any impurities in the pipe between the boiler and the valve.

With an arrangement as described above the control device controls not only the supply of water to the boiler but also controls operation of a burner that supplies heat to the boiler, the arrangement being that water is supplied to the boiler when the level of water in the control device falls below a predetermined value and also that heat is supplied to the boiler so long as the level of water in the control device is above a predetermined level.

There is a possibility that, with the previous forms of equipment, the valve can be left in a condition in which the control device is cut off both from the interior of the boiler and from exhaust. This means that, regardless of the level of the water in the boiler, there will be a substantially fixed level of water in the control device so that no further water will be pumped into the boiler but the burner will continue to operate with the danger that the boiler will boil dry. The control device may consist of a chamber containing a float valve or it may include electronic or other level sensing devices.

It is an object of the present invention to provide a new or improved form of equipment of the above kind, more particularly to provide a boiler in which the valve in the pipe connecting the interior of the boiler to the control device is such that the control device cannot be blanked off.

SUMMARY OF THE INVENTION

The present invention provides equipment of the kind referred to above in which the valve between the vessel and the control device comprises a valve body containing a chamber, a pair of valve seats within the valve chamber, which valve seats are located between connections to the vessel and to exhaust, a connection to the control device leading from the valve chamber between the valve seats, and a valve-operating member comprising a stem and a head, the head of the valve-operating member being movable between a pair of limiting positions in each of which it is in engagement with one of the valve seats to close either the connection to the vessel or the connection to exhaust and the valve head being arranged so that, in each limiting position and in any intermediate position, it does not close the connection to the control device.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is an end view of part of a boiler and a valve system connected thereto;

FIG. 2 is a sectional view of one of the valves;

FIG. 3 is a sectional view of another of the valves; and

FIG. 4 is a sectional view of an alternative form of valve to that shown in FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the arrangement shown in FIGS. 1 to 3, there is provided a generally conventional steam boiler 10 which includes a cylindrical shell 11 arranged with its axis horizontal, the shell containing means (not shown) for heating water inside it. On each side of the shell 11 and externally thereof there is provided a float chamber, 12, only one such chamber 12 being shown in FIG. 1, each chamber 12 containing a float valve (shown in outline in FIG. 1) which, when the level of the water in the chamber is above a predetermined level, cause a burner (not shown) for supplying heat to the boiler to be operative and the float valve also controls operation of a pump (not shown) for feeding water into the boiler when the level of water in the float chamber falls below a predetermined level. Other forms of level control devices e.g. electronic sensing devices (shown in outline in FIG. 1), may be provided.

A pipe 13 connects each float chamber 12 to the interior of the boiler, the two pipes 13 leading to the two chambers 12 being diametrically opposite to each other and at the same horizontal level. Each pipe 13 includes a horizontally extending portion 14 leading to a valve body 15 and a vertically extending portion 16 leading from the valve body 15, the valve body 15 being provided with flanges 17 for connection to said two portions 14 and 16 of the pipe.

The valve body 15 contains a generally elongated chamber 18 and at each end of the chamber 18 there is a valve seat 19 constituted by a stainless steel or plastics ring. The connection 20 to the boiler leads from the chamber 18 from one end thereof and, beyond the other valve seat 19 there is fitted an extension piece 21 which has an outlet 9 extending at right angles to the axis of the chamber 18. Between the two valve seats 19 there is a connection 22 extending from the chamber, said connection 22 being vertically disposed and arranged in communication with the float chamber 12. There is a valve-operating member 23 which comprises a stem 24 and a head 25, the head being of generally circular cross section and having a projecting lug 26 which is arranged to engage in a keyway 27 in a wall of the chamber 18 whereby the head 25 is prevented from rotating within the chamber and the diameter of the head 25 is the same as the diameter of the valve chamber 18. The stem 24 of the valve-operating member 23 is of less diameter than the head 25 and the head 25 has generally inclined end portions 28 which are arranged to engage the stainless steel or plastics sealing members 19. The length of the head 25 is less than the diameter of the connection 22 to the float chamber 12.

The stem 24 and the head 25 of the valve-operating member 23 are provided with a blind bore 29 which is threaded over a major portion of its length and the thread of the operating member cooperates with a mating screw thread formation formed on an operating spindle 30 received in the bore 29 whereby, on rotation, of the spindle 30 the valve-operating member 23, because it is prevented from rotating, by virtue of the engagement of the lug 26 in the keyway 27, is caused to move longitudinally within the chamber 18. Rotation of the spindle 30 is obtained by means of a manually operable handle 31 at the free end of the spindle 30 the spindle 30 passing through an aperture formed in a wall 32 of the extension piece 21 connected to the valve chamber 18 and sealing means 33 being provided between the spindle 30 and said wall 32 to prevent the escape of water or steam between the spindle 30 and said wall 32.

In use the valve-operating member 13 is in one limiting position as shown in chain-dotted lines in FIG. 2 so that one inclined end portion 28 of the head 25 of the operating member is in engagement with the valve seat 19 associated with the outlet 9 leading to exhaust whereby the boiler 10 and the float chamber 12 are in communication with each other. When it is desired to remove solid impurities from the pipe 13 between the boiler and the float chamber 12 the handle 31 at the end of the stem 30 is rotated to move the valve-operating member 23 axially within the chamber 18 out of engagement with said valve seat 19 into engagement with the valve seat 19 associated with the boiler as shown in full lines in FIG. 2. When the valve head 25 is in an intermediate position between the two valve seats 19 the connections to the boiler 10, the float chamber 12 and exhaust are all open so that impurities are blown out through the outlet 9. When the valve-operating member 23 is in its other limiting position, i.e. in engagement with the valve seat 19 associated with the boiler 10, the float chamber 12 is in communication with the exhaust whereby the float chamber 12 is emptied and the supply of heat to the boiler is thereby cut off. This arrangement ensures that the float chamber 12 is either in communication with the boiler 10 or in communication with the exhaust so that there is no possibility of the level of water in the float chamber 12 being higher than the level of the water in the boiler 10.

As mentioned above, there is a line 35 connecting the top of the boiler 10 to the top of each float chamber 12 for the supply of steam from the boiler to each float chamber 12, whereby, in use, the pressure in each float chamber 12 will be the same as that within the boiler, 10.

There is a single pipe 36 extending from the top of the boiler 10 to a T-junction 37 to which pipes 38 leading to the two float chambers are connected and there is a valve 39 located between the boiler 10 and the T- junction 37. Said valve 39 is in the form of a cock and, as shown in FIG. 3, includes a shutoff member 40 movable either into or out of engagement with a valve seat 41 constituted by the surrounds of an aperture 42 formed in a web 43 dividing the interior of the valve chamber 44 into two compartments. In use, the shutoff member 40 is normally out of engagement with said seat 41 to allow the flow of steam from the boiler 10 to the T-junction 37, the shutoff member 40 being in engagement with a further seat 45 located at the inner end of a subsidiary chamber 46 through the end wall 47 of which projects a spindle 48 for operating the valve. There is a bleed 49 leading from said subsidiary chamber 46 and the arrangement is that, when the valve member 40 is moved to the position shown in FIG. 3 to shutoff the connection between the boiler 10 and the T-junction 37 bleed 49 is in communication with the subsidiary chamber 46 of said valve and thus in communication with the atmosphere through the bleed 49. The bleed 49 contains a whistle so that, when the valve is operated to shut off the connection between the boiler 10 and the T-junction 37, steam from the float chamber 12 and the pipe between the T-junction 37 and the float chamber 12 issues through said bleed 49 to indicate to the operator that the valve is closed. The bleed 49 may alternatively contain a pressure or temperature control for sounding a remote alarm. This arrangement also ensures that should the steam in the line 35 between the T-junction 37 and each float chamber 12 condense, the pressure inside the float chambers 12 will not fall below atmospheric pressure as might cause water to flow from the inside of the boiler 10 into the float chambers 12 and therefore give a false reading of the level of water inside the boiler 10.

The valve shown in FIG. 4 may, in some circumstances, be used instead of the valve shown in FIG. 2 and includes a flange 50 for connection to the pipe 14 leading from the boiler and a flange 51 for connection to the pipe 16 leading to the float chamber 12. The flanges 50 and 51 are at the outer ends of cylindrical tubes 52 and 53 respectively and, at the junction of the two tubes 52 and 53 there is a generally cylindrical chamber in which the head 54 of a valve-operating member is located. The valve-operating member also includes a stem 55 and a handle (not shown) such as 31 shown in FIG. 2 provided for rotating the stem whereby the head 54 can be moved between the position shown in full lines in FIG. 4 and the position shown chain-dotted in FIG. 4. The valve of FIG. 4 also includes a tube 56 leading to an outlet 57.

The inner ends of the tubes 52, 53 and 56 can be considered as constituting valve seats and the head 54 of the valve-operating member is formed with a peripheral recess 58 which extends through an angle of 180.degree.. A projecting member (not shown) fixed to the stem 55 is arranged to engage stops carried by the valve housing whereby the operating member is prevented from being rotated anticlockwise beyond the position shown in full lines in FIG. 4 and prevented from being rotated clockwise beyond the position shown chain-dotted in FIG. 4.

In normal operation of the boiler the head 54 is in the position shown in FIG. 4 whereby the interior of the boiler communicates with the float chamber 12 through the recess 58 in the periphery of the head 54. When it is required to clean the pipe 13 extending between the float chamber 12 and the interior of boiler, the valve-operating member is rotated in the clockwise direction viewed in FIG. 4 whereby the recess 58 is moved into the position shown in chain-dotted lines and the connection to the interior of the boiler is shut off and communication between the float chamber 12 and exhaust is established. It is to be noted that, regardless of the position of the head 54, the float chamber 12 is at all times in communication with either the interior of the boiler or exhaust and that, when the head 54 is not in one of its limiting positions, the interior of the boiler can communicate directly with exhaust through the recess 58.

The valve shown in FIG. 4 thus operates in substantially the same way as the valve shown in FIG. 2.

Each float chamber 12 may include a level-indicating device such as a sight glass (not shown). Alternatively there may be a separate level-indicating device which is connected to the interior of the boiler through a valve the construction of which is either as shown in FIG. 2 or as shown in FIG. 4.

A preferred embodiment of the invention having been described, which is set forth by way of example only and not intended to limit the invention to which modifications evidencing a reasonable range of equivalents will become apparent to those skilled in the art.

Claims

I claim:

1. In equipment comprising a vessel for containing a liquid, a pipe connecting said vessel to a control device for controlling the supply of liquid to said vessel to maintain the liquid in the vessel at a substantially constant level, an exhaust outlet and a valve located in the pipe between the vessel and the control device, which valve is arranged to control the flow of liquid between the control device and the vessel and between both the control device and the vessel and exhaust, the improvement wherein the valve comprises a valve body containing a chamber, a pair of valve seats within the chamber, which valve seats are located between the interior of the chamber and connections to the vessel and to exhaust, a connection to the control device leading from the valve chamber between the valve seats, and a valve-operating member comprising a stem and a head, the head being movable between a pair of limiting positions in each of which it is in engagement with one of the valve seats to close either the connection to the vessel or the connection to exhaust and the valve head being arranged so that, in each limiting position and in any intermediate position, it does not close the connection to the control device.

2. Equipment according to claim 1 wherein the valve chamber is of elongated form with the valve seats located one at each end of the chamber and the valve-operating member is movable axially of the chamber.

3. Equipment according to claim 1 wherein the valve chamber is of generally cylindrical form with the valve seats located diametrically opposite each other, the head of the valve-operating member being rotatable between its limiting positions and stop means being provided for preventing movement of the operating member beyond its limiting positions.

4. Equipment according to claim 1 wherein the vessel is a steam boiler and there are a pair of control devices and a pipe between each control device and the boiler with said valve located in each pipe between the boiler and the control device.

5. Equipment according to claim 4 wherein the control devices include chambers containing float valves.

6. Equipment according to claim 4 wherein the control devices include electronic sensing devices.

7. Equipment according to claim 5 in which there is a line extending from the top of the boiler to the top of each float chamber, said line comprising a first pipe extending from the boiler and a T-junction to which pipes extending to the two float chambers are connected.

8. Equipment according to claim 7 wherein there is a manually operable valve located in the pipe between the boiler and the T-junction, said manually operable valve including an operating member movable from an open position in which the boiler communicates with the two pipes leading from the T-junction and a closed position in which the connection from the boiler is shut off but an exhaust outlet is opened whereby the two pipes leading to the T-junction are in communication with the atmosphere.