US2987885A - Regenerative heat exchangers - Google Patents

Description

June 13, 1961 J. HODGE REGENERATIVE HEAT EXCHANGERS 3 Sheets-Sheet 1 Filed July 2l, 1958 June 13, 1961 J. HODGE 2,987,885

REGENERATIVE HEAT EXCHANGERS Filed July 21, 195e s shexs-sheet 2 In ve nl or .fmes Hodge June 13, 1961 J. HODGE 2,987,885

REGENERATIVE HEAT EXCHANGERS Filed July 2l, 1958 5 Sheets-Sheet 5 y @Bmw/Shaw@ VMM@ United States Patent C 2,987,885 REGENERATIVE HEAT EXCIMNGERS James Hodge, Farnborough, England, assignor to Power Jets (Research & Development) Limited, London, England, a British company Filed July 21, 1958, Ser. No. 749,735 Claims priority, application Great 'Britain July 26, 1957 Claims. (Cl. 60-39.51)

The invention relates to a fuel control arrangement for plant incorporating a regenerative heat exchanger.

The heat transfer process in regenerative heat exchangers is of a cyclic nature, a heat storing matrix being alternately heated by heat transferred from a hotter fluid ow and cooled by transferring heat to a colder fluid flow. On changeover from the hotter uid ow to the colder fluid ow, the heated matrix is gradually cooled. Thus the rate of heat transfer to the colder fluid ow tends to decrease as the matrix becomes cooler. When such a regenerative heat exchanger is incorporated in a gas turbine plant for example, and in the absence of any correcting control, the turbine speed will tend to increase as the heat exchanger is changed over and decrease again thereafter.

The invention provides a fuel control arrangement in plant incorporating a regenerative heat exchanger matrix comprising a fuel control valve, a mechanism for changing the matrix from a position in a hot fluidpath to a position in a cooler uid path and an operative connection between the mechanism and the valve to control the fuel input to the plant in accordance with changes in the rate of heat transfer to the fluid owing through the matriX.

The invention further provides a fuel control arrangement including delay means allowing 'the fuel control valve to return to a predetermined position as the rate of heat transfer to the cooler fluid decreases.

The valve is preferably operable mechanically, or alternatively, pneumatically or hydraulically by the changeover mechanism.

The invention further provides a fuel supply control arrangement in a gas turbine plant including a heat exchanger matrix in two portions, each portion being alternately positioned in the path of hot exhaust gases from the turbine and in the path of cooler compressed air and simultaneously in a different path from the other, comprising a fuel supply valve tothe combustion system, a mechanism for changing over thematrix positions and a controlling interconnection between the mechanism and the valve so arranged that changeover is followed first .by a decrease of fuel supply and secondly by a restoration thereof. l

Some embodiments of the invention will now be described by way of example only with reference to FIG- URES 1-4 of the accompanying diagrammatic drawings, in which:

FIGURE l shows a heat exchanger of the piston type incorporated in a gas turbine plant with a lever system for operating a fuel valve (the fuel valve not being shown in detail);

FIGURE 2 shows a more detailed arrangement of the fuel valve and lever system and means intermediate the fuel valve and the lever system to control the position of the fuel valve;

FIGURE 3 shows an arrangement in which the fuel valve is fluid controlled;

FIGURE 4 shows an alternative arrangement for fluid control of the fuel valve.

FIGURE l shows an arrangement of a piston type heat exchanger incorporated in a gas turbine plant including a compressor 33, a turbine 34 and a combustion chamber 35. A heat exchanger matrix is shown in two parts A s ICC and B. Both parts A and B of the matrix are mounted on a movable ported sleeve 32. A ported cylindrical casing 30 surrounds a hollow shaft 38 which supports the sleeve. Attached to the sleeve 32 is a rod 36 which is joined to an arm 3 pivotable about a point 3A. Connected to each end of the arm 3 are linkages 1 and 2, which are shown in part only in FIGURE 1. Hydraulic plungers 37 and 37A are connected to the sleeve 32. Ducting to lead uid to operate these plungers is shown in part at 39 and 40. The ported cylindrical casing 30 has flanges which project radially inwardly towards the periphery of the heat exchanger matrix and towards flanges which extend radially outwardly from the ported sleeve 32. The flanges from the casing 30 define with the matrix and the flanges from the ported sleeve 32 four annular chambers 30A, B, C and D. The chambers 30B and 30C communicate with ducting 34A which is connected to the combustion chamber 35 and from the combustion chamber to the inlet of the gas turbine 34. Ducting 34B conveys the exhaust gases from the turbine 34 to a port 42 situated between the chambers 30B and 30C. The chambers 36A and 30D are ported to allow exhaust gases leaving part A and part B of the matrix to discharge. The compressor 33 has its delivery connected by ducting 33A to a port 41 in the left hand side of the cylindrical casing 30. A fuel line 17 is connected to the combustion chamber 35 and in the fuel line is positioned a main fuel valve 9A and a fuel valve 9 which is controlled by the arrangements shown in FIGURES 2-4 of the drawings, and hereinafter more fully described.

The fuel valve 9 can alternatively be positioned in a fuel line by-passing the main fuel line and this is shown by the broken line connection to the combustion charnber 35.

The operation of the heat exchanger will now be described with reference to FIGURE 1. In FIGURE l the position of the sleeve 32 together with parts A and B of the matrix relative to the chambers 30A, B, C and D and port 42 is such that compressed air from the compressor 33 passes through the port 41, is prevented from flowing into the chamber 30D by the co-operating tlanges of the sleeve 32 and casing 30, but llows as indicated by the full line arrows through part A of the matrix and out into the duct 34A. The compressed air is thus heated by passage through part A of the matrix. This part of the matrix has previously been heated in a manner to be' subsequently described. Part B of the matrix receives exhaust gases from the turbine via duct 34B which pass out through the port in the chamber 30D as shown by the full line arrow. When parts A and B of the matrix are moved to the right by the plunger 37, the compressed air will flow through the hollow shaft 3S as shown by the broken line arrows and will flow through part B of the matrix and after being heated by the part B of the matrix passes into duct 34A into the combustion chamber. Part A of the matrix in this position receives heat from the ow of exhaust passing through it from right to left as shown in broken line arrows. Thus part A of the matrix is first heated and then cooled while at the same time the part B of the matrix is being cooled and then heated. Any lateral movement of the matrices causes lateral movement of the rod 36. When the matrices are moved towards the left hand side of the casing 30, in which position part A of the matrix commences to receive the cooler uid from the compressor 33, the linkage 2 moves in a `direction away from the casing 30 and effects control of the fuel valve 9 as will be subsequently de.- scri-bed. When the matrices are moved towards the right hand side of the casing 30 part B of the matrix commences to receive the cooler uid from the conipressor 33. In thisv case linkage 1 moves vin a direction 3 away from the casing 30 and effects control of the fuel valve 9.

FIGURE 2 of the drawings shows the two linkages 1 and 2 rconnected to the radially outer ends. of levers 4 and 5. Mounted coaxially with the. levers 4V and 5 is a cam 6 which carries four lobes 6A, 6B, 6C and 6D, each 90 from one another. Ratchets 7 and 8 are positioned on a single shaft and are mounted coaxially with the levers 4 and 5 together with the cam 6. In FIGURE 2 the ratchet 8 is shown to the left of ratchet 7y for purposes of clarity. Ratchet 7 provides driving engagement between the lever 4, and the cam 6 in the anticlockwise direction, while ratchet 8 provides drivingV engagement between the lever and the cam 6 in a clockwisedirection. The fuel throttle 9 has a stem 10V which carries a piston 11. The tip of the valve stem 10` is positioned to be moved vertically downwards by Contact with any one of the cam lobes 6A, B., C or D. The piston 11 is slidably housed in a valve housing 12 and is biased to its uppermost position by a spring 13 situated in the housing l2 between the base thereof and the undersurface of the piston 11. A conduit 13A joins the housing 12 and a receiver 14. In the conduit 13A is a one way valve 15 and a restriction 16. The fuel throttle valve 9 extends into the fuelfpipe 17.

The operation of the fuel control arrangementV will now be described with reference to FIGURE 2 ofthe drawings: Y

Linkage 2 is concerned with affecting. fuel control fo part A of the heat exchanger matrix. The linkage 2 is moved in the direction of the arrow X by the mechanism which changes over theheat exchanger fluid flows. The valve stem 1G is in the position 10A shown by the broken line outline. The movementof the linkage 2 turns each of the lobes through 90 by means of the ratchet 8. Thus lobe 6D is brought into the position which was previously occupied by lobe 6A. As the curved leading edge of lobe 6D contacts the valve stem 10 it depresses it and places the throttle valve 9 into a reducedV ow position. Oil` contained in the housing 12 isl displaced by the downward movement of piston 11 and flows into the receiver 14 by way of the conduit 13A and one way valve 1S. When the lobe 6D has completed its movement the back edge thereof allows the valve stem- 10 to be returned gradually to its initial position by the spring 13 and by oil returning slowly from the housing 12 from the receiver 14 by way of restrictor 16. Movement of the linkage 2 in the direction shown by arrow X causes the pivot arm 3A to pivot in the clockwise direction. Linkage 1 is thus moved in the direction shown by arrow Y and lever 4 is moved into the position 4A. The lever 4 does not engage the ratchet 7 when it is moved into the position 4A. vWhen linkage 1 is moved by the changeover mechanism in the direc tion shown by arrow Z, the lever 4 is movedV from its position 4A to engage with the ratchet 7 which consequently displaces each of the cam lobes 6A-D in the same direction as occurs when lever 5 was movedY into the position 5A. Thus during the changeover movement forV one part of the heat exchanger, lever 5 drives the cam 6 and for the other part of the heat exchanger matrix, lever 4 drives thecarn 6.

FIGURE 3 of thedrawings shows an arrangement which is suitable for heat exchangers in which the f orce for operating the changeover mechanism, which, may be hydraulic or pneumatic, is maintained duringV the Vchange.-V over period only. Many of the elements of the arrangement of FIGURE 3 also appear in FIGURE 2 and suchY elements have the same Vreference numerals. Above the piston 11, theV valve housing 12 is connected by a., conduit 18to conduits 19 and 20 which convey fluid tooperaV ating uid from the ducts 39 and 40 the 'remainderA of' Vconnection with FIGURE 3.

4 the heat exchanger mechanism, being the,- saine` as that shown in FIGURE 1. In the conduit 18 is a leak valve 29 and a restriction 21 is placed adjacent thereto. In supply conduits 19 and 20 respectively non-return valves 19A and 20A are positioned.

At the commencement of the changeover for part A of the heat exchanger matrix the operating duid passes into the conduit 19 and passes via the one way valve 19A into the conduit 18 to depress the piston 11/ and restrict the fuel supply. The restrictor 21 provides a predetermined delay in operation. When the changeover is complete, the operating pressure ceases and the operating uid escapes via the leak valve 29', allowing the throttle valve 9 to return to its initial positon under the influence of the spring 13. At the commencement of the changeover part B of the heat exchanger matrix, the operating fluid passes through conduit 20, non-return valve 20A and depresses the valve to reduce the fuel input through conduit 14 in the same way as before.

FIGURE 4 of the drawings shows an arrangement which is suitable Vfor heatexchangers in which the force for operating the changeover mechanism is maintained from one changeover to the following changeover. For changeover mechanisms of this type it is necessary to incorporate a cyclic shut-off valve since otherwise the fuel supply valve will not return gradually to its initial position. This arrangement is similar to that shown in YFIGURE 3 except that a cyclic shut-off valve shown generally at 22 is provided bettween the conduits 19- and 2%.

and their respective non-return valves 19A and 20A. The cyclic shut-off valve 22 comprises a piston 24 on either side of which are springs 25 and 26,. The piston 24 carries on either side a valve stem terminating in valve members 27 and 2S. These valves operate to permit operating fluid either through the non-return valve 19A or alternatively through non-return valve 20A.

When the operating uid is supplied through conduit 19 the fuel throttle valve 9 is operated as described in I Y When the pressureV of the operating fluid has built up to a certain value determined by the strength ofv the springs 25 and 26, the piston will be displaced to the right and the valve member 27 will shut-olf the supply of operating uid through conduit 19. The throttle valve 9 will then return to its upper position, the operating uid passing out through leak valve 29 as before. The operation when operating fluid is passed through conduit 20 is the reverse tov `that when operating Huid isy passed through conduit 19.l

What I claim is: Y

1. A fuel control arrangement in plant incorporating a regenerative heat exchanger comprising aV heatl exchanger matrix, ducting to convey heated uid andvv relatively cooler fluid to the matrix, ducting to convey these fluids away from the matrix after an interchange of heat content between them, structure locating said-ducting, Vdriving means between, the structure andthe matrix to provide cyclic relative motion between the ductingy and the matrix to interchange said matrix betweena position in the path of the heated fluid and a position inz the path of the relatively cooler fluid, a fuel control valve for the plant and a connection between said driving means and said fuel valve, the fuel valve being phased bythe Y relative motion viasaid connection, between a reduced fuel flow position and an increased fuel flow position respectively over the period from ythe commencement to the termination of a cycle of heat interchange between the matrix and the relatively cooler fluid.

' 2. A fuel control arrangement in plant'incorporating a regenerative heat exchanger comprising al heat exchanger matrix, ducting to convey heated iuid and relativelyvcooler fluid to the rnatiix,r ductingy `to convey these liuids away from the matrix after an interchangeof heat content between them, structure locating Asaid ducting,4 driving meansv between the structure andthe matrix to` provide cyclic relative motion. between the. ducting and. Vthe matrix to interchange Asaid matrix between a position in the heated fluid path and the relatively cooler fluid path, a fuel control valve for the plant, said fuel valve incorporating delay means and a connection between said driving means and said fuel valve, the relative motion displacing the fuel valve via the connection into a position of reduced fuel ow when the matrix first communicates with the cooler fluid flow and after a delay determined by the delay means placing the fuel valve to a normal increased fuel flow position.

3. A fuel control arrangement in gas turbine plant incorporating a regenerative heat exchanger comprising a heat exchanger matrix, said matrix being in two parts, each part being alternately positioned in a path of hot exhaust gases from the turbine and in the path of cooler compressed fluid and simultaneously in a different path from the other, comprising a fuel supply valve to the combustion system, driving means to change the position of the matrix between the paths, a lever and cam system between the driving means and said fuel valve, the cams displacing the fuel valve to a reduced fuel flow position following a change of position of either part of the matrix to the path of cooler compressed fluid, and a delay device associated with said fuel valve, the cams allowing the fuel control valve to return to a normal increased fuel ow position after an interval of time determined by the delay device.

4. A fuel control arrangement in plant incorporating a regenerative heat exchanger comprising a heat exchanger comprising a heat exchanger matrix, ducting to convey heated fluid and relatively cooler fluid to the matrix, ducting to convey these uids away from the matrix after an interchange of heat content between them, structure locating said ducting, pressure uid motor means, uid conduit means to convey iluid to operate pressure fluid motor means, which pressure fluid motor means provide cyclic relative motion between the locating structure and the matrix to interchange said matrix between a position in the heated path and a position in the relatively cooler iluid path, a fuel control valve for the plant, fluid actuating means to operate the fuel control valve, a duct connection between the fuel control valve and the fluid conduit means to convey fluid to operate the iluid actuating means, a restriction located in the duct connection between the fuel control valve and a valve means which valve means, when in an operating position, causes the fuel control valve to move to a reduced fuel flow position when either part of the matrix commences to receive the cooler uid ilow after a delay determined by the flow restriction.

5. A fuel control arrangement as claimed in claim 4 in which the valve means comprises a cyclic shut-olf valve in the duct connection.

References Cited in the file of this patent FOREIGN PATENTS 690,800 Great Britain Apr. 29, 1953

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