GB2323428A

GB2323428A - Valve arrangement to control flow to burners

Info

Publication number: GB2323428A
Application number: GB9805507A
Authority: GB
Inventors: Anthony Giovanni Salsi
Original assignee: Vosper Thornycroft Controls Ltd
Current assignee: Rolls Royce Marine Electrical Systems Ltd
Priority date: 1997-03-18
Filing date: 1998-03-17
Publication date: 1998-09-23
Also published as: AU6412998A; GB9805507D0; WO1998041796A1; GB9705528D0

Abstract

A valve arrangement for the control of flow of fluid to burners comprises a first, control valve (501) through which the fluid is supplied to a second valve (502, 1). The second valve (502, 1) having a plurality of outlets (503, 01 to 07), each outlet supplying the fluid directly to a dedicated burner (504) or group of burners (504). Each outlet (503, 01 to 07) is openable in an individual predetermined manner whereby each dedicated burner (504) or group of burners (504) can receive a uniquely programmed supply of fuel.

Description

VALVE This invention relates to a valve and in particular to a valve for controlling a supply of fluid, e.g. a gaseous or liquid fuel. The fuel may be supplied e.g. to the burners of a gas turbine engine.

Although the valve of the invention, therefore, is particularly useful in the supply of fuel to the burners of a gas turbine engine and the invention will, for convenience, be more specifically described below with reference to gas turbine engines, it will be appreciated that its uses are not so limited.

It is desirable to reduce the undesirable exhaust emission of burners and to achieve such a reduction it is necessary to increase burning efficiency by more accurate proportioning of the fuel to the burners and by more effective atomising of the fuel particles and better mixing of the fuel and oxygen.

It has been proposed to reduce the undesirable exhaust emissions from gas turbine burners by use of multiple valves to supply the fuel to the burners. Such multiple valves require extremely accurate fuel metering controls if they are to be successful.

It is an object of the present invention to provide an improved valve arrangement that can reduce undesirable exhaust emissions without the need for such a high degree of complexity of metering control and that can replace the aforesaid multiplicity of high precision valves with an arrangement of a multiplicity of valves comprising essentially a single high precision valve feeding a plurality of valve outlets, wherein the plurality of valve outlets is not required to be of such high precision.

Accordingly, the invention provides a valve arrangement for the control of flow of fluid to burners, the arrangement comprising a first, control valve through which the fluid is supplied to a second valve, the second valve having a plurality of outlets, each outlet supplying the fluid directly to a dedicated burner or group of burners, each outlet being openable in an individual predetermined manner whereby each dedicated burner or group of burners can receive a uniquely programmed supply of fuel.

In a first embodiment all the second valve outlets may be housed in a single second valve body, wherein each outlet is opened in a desired predetermined sequence by being brought into registration with an associated port of the valve, drive means being provided to bring each port sequentially into registration with its associated outlet, whereby the amount of fluid passing through each outlet and the sequence of opening of the outlets can be controlled.

In a second embodiment, the plurality of second valve outlets comprises a plurality of separate second valves with drive means to open the valve outlets in the desired sequence.

Thus the valve arrangement may have a single fluid supply to its control valve and the rate of flow of fluid may be steady at a predetermined rate, which steady rate may be changed as required, and may be apportioned between the various outlets.

By this means only the first, control valve need be manufactured to the requisite degree of high precision necessary and the second valve(s) can be manufactured to lower tolerances. Hence the advantages of use of multiple valves to supply fuel to burners can be achieved in a less expensive and more reliable manner.

In the above mentioned first embodiment the valve outlets may be integral with or attached to a first member of the second valve and the valve ports may be formed in a second member of the valve, the second member being connected to the inlet to receive the supply of fluid which then passes through the ports, the second member being movable relative to the first member by the drive means to bring each port sequentially into registration with its associated outlet.

Control means including associated software may be used as is conventional in the art to control the drive means.

Where the valve arrangement is to feed fuel to the burners of a gas turbine, each outlet may be connected to a single burner or to a group of burners. Each burner or group of burners can, therefore, be supplied with a predetermined amount of fuel in a predetermined sequence from a single control valve and a multi-outlet valve or valves.

One or more of the outlets may be permanently open, e.g. in the above-mentioned first embodiment one or more outlets may be permanently in registration with the corresponding port(s), e.g. to provide fuel to one or more pilot burners.

The ports in the second valves may be variously shaped holes or slots. Such holes or slots may be of constant or varying shape or width.

Thus the size of the hole or length of slot and its width will determine respectively the period of time for which fluid may flow through the associated outlet and the amount of fluid flowing through the outlet in that time. Hence the amount of fluid passing through the outlet in a given time period is controlled.

There are various mechanical configurations which may encompass the principles of the invention. Thus, for example the second valves may take a variety of physical forms, e.g. cylindrical housings, plates or poppet valves.

In one particular construction of the above-mentioned first embodiment, i.e. the second valve outlets being in a single second valve body, the second valve comprises a valve body having an interior cavity of circular cross-section and a plurality of outlets connecting the cavity to the exterior of the body, a hollow rotatable valve member of circular cross section having an outside diameter slightly less than the internal diameter of the interior cavity of the body retained coaxially within the cavity, the member having an inlet, a wall capable of covering at least some of the outlets and a plurality of ports, each one of said ports being associated with one of said outlets and alignable therewith to uncover the associated outlet, drive means to cause the valve member to rotate within the cavity and allow fluid to flow through the inlet into the hollow member and out through each associated port when it is aligned with one of said outlets, a predetermined amount of fluid thus flowing through each outlet in a required sequence.

Preferably in this embodiment the valve body comprises a cylindrical tubular wall sealingly secured to two end plates, the valve member comprises a cylindrical wall and two circular ends, the valve member being arranged coaxially within the interior cavity of the valve body, and the drive means comprises a drive shaft located in a bearing in one of the end plates of the valve body and being connected to one of the ends of the valve member.

The inlet may comprise a tube connected to the other of the two end plates of the valve body and passes through the other of the two ends of the valve member. The tube may be located on the rotational axis of the valve member and pass through a seal in said other end thereof.

The outlets may be positioned on the wall of the valve body, a plurality of connectors being attachable one to each outlet. Each outlet may be provided with an orifice of predetermined size to provide control for the amount of fluid passing through each individual outlet.

As indicated above, each port may comprise a hole or slot formed in the wall of the valve member, the length of each slot extending in a circumferential direction with respect to the axis of rotation of the valve member. The circumferential length of each port thus determines the period of time for which fluid may flow to the associated outlet, depending on the speed of rotation of the member. Depending on the size of the orifice, the amount of fluid passing through the outlet in the time period is controlled.

The drive shaft may be rotatably driven by means of a motor through an appropriate drive train.

Valves of the invention can be used with advantage to supply fuel to any design of gas turbines having multiple burners. Thus the invention is equally applicable, for example, to a gas turbine whose combuster has a series of spaced burners along its length and where fuel is injected sequentially at each burner or group of burners, and to a gas turbine whose combuster has a series of ring burners from the centre of the combuster to its outer limits where fuel may be injected sequentially starting, say, from the centre and working outwardly, or in any suitable pattern which provides for low exhaust emissions.

Embodiments of the invention will now be described by way of example only, with reference to the accompanying drawings in which: Figure 1 shows a longitudinal cross-section through a second valve in accordance with a first embodiment of the invention, parts being omitted for clarity; Figure 2 shows a side view of the valve shown in Figure 1; Figure 3 shows an end view on arrow Ill of the valve shown in Figure 2; Figure 4 shows a cross-section on line IV-IV of Figure 2; Figure 5 shows a section on line V-V of Figure 2; Figure 6 shows the valve ports on a developed cylinder; Figure 7 is a diagrammatic illustration in perspective view of a second embodiment of the invention; Figure 8 is a similar view to Figure 7 of a third embodiment of the invention; and Figure 9 is a diagrammatic representation showing a general layout of the invention.

As shown in Figures 1 and 2 the second valve of the present invention, which is to be fed from a high precision control valve (not shown but see Figure 9), comprises an outer valve body 1 having a plurality of outlets 01, 02, 03, 04, 05, 06 and 07, an inner valve member 2 and two end plates 3, 4. In use fuel is fed into the valve member from a control valve and passes out through the outlets in a controlled sequence and in controlled amounts and from thence into the burners of a gas turbine engine.

The valve body 1 comprises a cylindrical tube 6. Adjacent each end is a portion 7 of reduced external diameter and at each end is a bevelled surface 8. The valve body 1 also comprises two square end plates 3, 4 each having a circular recess 5 on one side to receive the reduced diameter end portion 7 of the tube 6. O-rings 9 are provided at the periphery of the bases of the recesses, which sealingly engage the bevelled surfaces 8 of tube 6. The tube 6 and two end plates 3, 4, are held together by means of four rods 10, both ends 11 of each rod passing through holes 12 formed in the corners of each end plate 3, 4. The ends 11 of the rods are screwthreaded and receive nuts 13, which on tightening pull the end plates 3, 4 towards one another and compress the rings 9 against the bevelled surfaces 8 to seal the tube 6 in the recesses 5.

Both end plates 3, 4 are formed with further circular recesses 14 on the outer surfaces thereof i.e. on the opposite sides to the recesses 5 for receiving the ends of the tube 6. The further recesses 14 are each of a smaller diameter than the recesses 5. A central bore 15 passes through each plate connecting the two recesses.

In one end plate 4 (shown at the left-hand side of Figure 1) the further recess 14 is provided with an internal screw thread at 16 for receiving a connector (not shown) attached to a pipe (not shown) through which fuel may be fed to the valve. The central bore 15 extends through a short tube 17 secured to e.g. by welding, or integrally formed with the end plate at the centre of the recess 5.

In the other end plate 3 (at the right-hand side of Figure 1) a further recess 14 contains a bearing 18 held in position by a circular cover plate 19 attached to the outer surface ofthe end plate by screws 20.

A plurality of outlets 01, 02, 03, 04, 05, 06 and 07 is welded to the outer surface of the cylindrical tube 6. The outlets are arranged in two rows extending longitudinally of the tube, one row being diametrically opposite the other row, as shown in Figure 2. The outlets are connected to burners (not shown).

Housed coaxially within the valve body 1 is a cylindrical valve member 2 comprising a tube 25 having an external diameter slightly less than the internal diameter of the tube 6 of the valve body 1 and a length slightly shorter than the distance between the bases of the recesses 5 of the two end plates 3 and 4. One end (at the right-hand side of Figure 1) of the tube 25 of the valve member 2 is sealed by a disc 27 welded to the interior surface thereof. At the centre of the disc 27 is welded a shaft 28 which passes through and is capable or rotating in the bearing 18 housed in end plate 3. The shaft 28 has an enlarged portion 29 immediately adjacent the disc and this is provided with a seal 30 which engages the interior of the bore 15 in the end plate 3. A circlip 1 8A prevents the shaft from moving within the bearing 18.

The other end of the tube 25 is provided with a further disc 32 welded to the interior thereof. The further disc 32 has a hole at its centre lined with a sleeve 60 which acts as a bearing against the external surface ofthe short tube 17.

The tube 25 is provided with a plurality of ports 27A each associated with one of outlets 01, 02, 03, 04, 05, 06 and 07. The ports 27A are either circular holes or elongated slots and as the valve member 2 rotates the ports 27A uncover the respective outlets to allow fuel to pass from the interior of the member through the port and through the outlet. A typical arrangement of ports 27A is shown in Figure 6 which shows the cylindrical tube 25 developed as a rectangle.

The outlets are of two constructions: one construction is shown in Figure 4 and the other is shown in Figure 5. Outlets 01 and 07 are as shown in Figure 4, outlets 02, 03, 04, 05 and 06 are as shown in Figure 5.

As shown in Figure 4, the outlet 07 comprises a tubular bush 130 welded to the exterior surface 131 of the valve body 6 to surround an aperture 132 therein. The bush has an enlarged internally screw-threaded mouth 133 within which is located an internally and externally screwthreaded tubular connecting member 134. The connecting member has a hexagonal head 136 which may be engaged by a spanner to tighten or loosen it. The connecting member has a conical end surface 137 against which an O-ring seal 138 provided at the base of the mouth portion of the bush 130 may be compressed on tightening the connecting member, The connecting member has an interior flange 139 which holds an orifice disc 140 and a spacing washer 141 against the base of the mouth portion. The disc 140 has an orifice 142 formed therein to define the flow rate of fuel through the outlet, through a pipe (not shown) connected by means of the connecting member to the outlet to a burner (not shown).

As can be seen in Figure 4 there is a gap 144 between the outer surface of the tube 25 of the valve member 2 and the inner surface of the tube 6 of the valve body 1. This means that fuel can flow continuously from the interior of the valve member through any or all of the ports 27A in the member into the gap 144 and out through the outlets O1 and 07.

As shown in Figure 5 the outlet OS comprises a tubular bush 150 welded to the outer surface 131 of the valve body and a connecting member 152. The bush 150 and connecting member 152 are the same as the bush 130 and the connecting member 134 shown in Figure 4. The connecting member 152 is provided with an internal flange 154 which holds a spring 155 against the end of a tube 156 which fits tightly in the bore of the bush and an aperture 157 formed in the tube 6. The tube 156 extends through the bush, through the aperture 157 in the body to sealingly engage the outer surface 158 of the tube 25 of the valve member. As shown in Figure 5 the end of the tube 156 is covered by the wall of the tube 25 so no fuel can flow from the interior of the valve member, or from the gap 144 into the outlet O5. However, as the member rotates and a port 27A aligns with the end of the tube 156, fuel can flow from the interior of the member 2 through the aligned port 27A, through the tube 156, and thence out through the outlet via a pipe (not shown) connected to the connecting member 152 and thence to a burner (not shown). The rate of flow of fluid is defined by the diameter of the bore of the tube 156 but a disc with an orifice may be provided if required lying alongside the spring 155.

In use, fuel is fed into the valve of the invention through the central bore 15 of the end plate 4 (shown at the left-hand side of Figure 1) through the short tube 17 and into the interior of the valve member 2. The valve member is rotated by means of a motor (not shown) drivably attached to the drive shaft 28 (at the right-hand side of Figure 1). As the valve member rotates fuel passes out of the ports 27A into the gap between the inner tube 25 of the valve member and out through the outer tube 6 of the valve body and out through the outlets Ol and 07 continuously. In addition, as the apertures 27A associated with the outlets 06, 02, 03, 04 and O5 move into alignment therewith, measured amounts of fuel flow out of each outlet, the amount depending on the size of the apertures and the sizes of the orifices in each outlet. The sequence of flow through each outlet depends on the relative positions and shapes e.g. circular, elongated, or tapered etc., of the apertures.

One such sequence is indicated by way of example in Figure 6 and is such that 07 and Ol are fully variable types.

It will be appreciated that this sequence and the arrangement of slots are purely for illustration and that the skilled man will readily be able to formulate different arrangements of slots/ports and different sequences to suit his particular fluid supply requirements.

Figure 7 shows a plurality of separate second valves only three of which are shown, 010, 020, 030, connected at their inlets 201, 202, 203, to a common fuel manifold supplied by a control valve (not shown). Each valve output 204, 205, 206, is connected to the burner or burners of a gas turbine 207. As above, the ports in each valve may be shaped to suit the fluid flow requirements of the particular application. All valve operating shafts are coupled together with slipping couplings 208, 209, so that the opening and closing sequence between valves may be controlled.

An alternative arrangement of a plurality of second valves is shown in Figure 8. Here the second valves 001, 002, 003, etc. are again connected at their inlets 301, 302, 303 to a common fuel manifold and control valve (not shown). However, each second valve is driven by a separate motor 401, 402, 403. Thus the sequence and rates of fluid flow change may be independently controlled by software means.

In Figure 9, is shown a general valve layout for the invention. Fuel is supplied via an outlet 500 to a first, control valve 501. Valve 501 supplies the fuel to a second valve 502 having a plurality of outlets 503 leading to burners 504.

Claims

1. A valve arrangement for the control of flow of fluid to burners, the arrangement comprising a first, control valve (501) through which the fluid is supplied to a second valve (502, 1), the second valve (502, 1) having a plurality of outlets (503, Ol to 07), each outlet supplying the fluid directly to a dedicated burner (504) or group of burners (504), each outlet (503, Ol to 07) being openable in an individual predetermined manner whereby each dedicated burner (504) or group of burners (504) can receive a uniquely programmed supply of fuel.

2. A valve arrangement according to Claim 1, in which there is a single fluid supply (500) to the control valve (501) and the rate of flow of fluid may be maintained at a steady but changeable predetermined rate.

3. A valve arrangement according to Claim 1 or 2, in which the second valve or valves (502, 1) is/are made to lower precision tolerances than the control valve (501).

4. A valve arrangement according to Claim 1, 2 or 3; including software to control the sequential opening of the valve outlets (503, O1 to 07).

5. A valve arrangement according to any preceding claim, in which each valve outlet (503, Ol to 07) is connected to a single burner (504) or a group of burners (504) of a gas turbine.

6. A valve arrangement according to any preceding claim, in which one or more of the valve outlets (01, 07) is permanently open.

7. A valve arrangement according to any preceding claim in which the second valve outlets (01 to 07) are housed in a single second valve body (1) wherein each outlet is opened in the predetermined sequence by being brought into registration with an associated port (27A) of the valve, drive means being provided to bring each port (27A) sequentially into registration with its associated outlet (01 to 07), whereby the amount of fluid passing through each outlet (01 to 07) and the sequence of opening of the outlets can be controlled.

8. A valve arrangement according to Claim 7, in which the ports (27A) in the second valve (502, 1) include circular holes and slots of different length and width.

9. A valve arrangement according to Claim 7 or 8, in which the valve outlets (01 to 07) are attached to or integral with a first member (6) of the second valve (502, 1), a second member (2) being connectable to the inlet to receive the supply of fluid which can then pass to the ports (27A), the second member (2) being movable relative to the first member (6) by the drive means to bring each port (27A) sequentially into registration with its associated outlet (01 to 07).

10. A valve arrangement according to Claim 7, 8 or 9, in which the second valve (502, 1) comprises a valve body (1) having an interior cavity of circular cross-section and a plurality of outlets (01 to 07) connecting the cavity to the exterior of the body, a hollow rotatable valve member (2, 25) of circular cross-section housing an outside diameter slightly less than the internal diameter of the interior cavity of the body (1) retained coaxially within the cavity, the member (2, 25) having an inlet (17), a wall capable of covering at least some of the outlets (01 to 07) and a plurality of ports (27A), each one of said ports (27A) being associated with one of said outlets and alignable therewith to uncover the associated outlet, drive means to cause the valve member (25) to rotate within the cavity and allow fluid to flow through the inlet into the hollow member and out through each associated port (27A) when it is aligned with one of said outlets (01 to 07), a predetermined amount of fluid thus flowing through each outlet in a required sequence.

11. A valve arrangement according to Claim 10, in which the valve body (1) comprises a cylindrical tubular wall sealingly secured to two end plates (3, 4), the valve member (25) comprises a cylindrical wall and two circular ends, the valve member being arranged coaxially within the interior cavity of the valve body (1), and the drive means comprises a drive shaft (28) located in a bearing (18) in one of the end plates (3) of the valve body and being connected to one of the ends of the valve member.

12. A valve arrangement according to Claim 11, in which the inlet comprises a tube (17) connected to the other of the two ends of the valve member.

13. A valve arrangement according to Claim 12, in which the tube (17) is located on the rotational axis of the valve member and passes through a seal in the other end thereof.

14. A valve arrangement according to Claim 11, 12 or 13, in which one or more of the ports (27A) comprises a slot in the wall of the valve member (25), the slot extending longitudinally in a circumferential direction with respect to the axis of rotation of the valve member.

15. A valve arrangement according to any one of Claims 1 to 6, in which the second valve outlets (204, 205, 206) comprise a plurality of separate second valves (010, 020, 030) with drive means to open the valve outlets in the desired sequence.

16. A valve arrangement according to Claim 15, in which the plurality of second valves (010, 020, 030) are connected to a common fuel manifold supplied by the control valve (501).

17. A valve arrangement according to Claim 16, in which each second valve (010, 020, 030) has a drive shaft coupled to the adjacent second valves with slipping couplings (208, 209).

18. A valve arrangement according to Claim 15, in which each second valve (001, 002, 003) is driven by a separate motor (401, 402, 403).

19. A valve arrangement according to Claim 1, substantially as hereinbefore described with reference to and as shown in Figures 1 to 6 and 9 of the accompanying drawings.

20. A valve arrangement according to Claim 1, substantially as hereinbefore described with reference to and as shown in Figure 7 or Figure 8 of the accompanying drawings.