US2923575A - Fuel feeding mechanism for a gas turbine - Google Patents

Description

Feb. 2, 1960 R. C. ALLEN FUEL FEEDING MECHANISM FOR A GAS TURBINE Filed March 19, 1956 mommy FUEL FEEDING MECHANISM FOR A GAS TURBINE Robert C. Allen, Wauwatosa, Wis., assiguor to Allis-Chalmers Manufacturing Company, Milwaukee, Wis.

Application March 19, 1956, Serial No. 572,419

4 Claims. (Cl. 302-55) This invention relates generally to gas turbines. More particularly this invention relates to a structure for feeding fuel into the combustion chamber of a gas turbine especially the coal burning type.

One of the problems facing the gas turbine industry is providing an efficient means for feeding fuel from its source, for example, a hopper, at atmospheric pressure into the combustion chamber of the gas turbine power plant which is at the cycle pressure of the plant. The cycle pressure of gas turbine power plants is considerably higher than atmospheric pressure and there is a tendency to force air from the turbine into'the source of fuel which renders the feeding process inoperative.

This phenomenon is known as a blowback. Variouswell known valve structures have been applied to fuel feeding devices in an attempt to seal the source of fuel from the high pressure zone of the turbines while a predetermined charge of fuel is being injected into the combustion chamof a gas turbine and valve means positioned at either end of the member to collapse and thereby seal the member at appropriate times during the feeding cycle, to effectively seal the source of fuel from the high pressure air in the turbine during the fuel feeding cycle.

The flexible member is made of a material having good resistance to the abrasive wear of the powdered coal, such as rubber, in order to preserve the sealing qualities of the flexible member. The flexible member has a separate relief tube vented to atmosphere which has sealing means which. operate in coordination with the sealing means of the flexible member.

A vibrator is mounted on the member to aid the gravitation feed of fuel through the member into the combustion chamber.

Therefore it is the object of this invention to provide a new and novel device for feeding fuel from a source at atmospheric pressure into the high pressure zone of a gas turbine power plant. 1

Another object of this invention is to provide a new and novel device for feeding fuel into a gas turbinethat will seal the source of fuel fromthe high pressui'e zone of the turbine power plant during the feeding operation and thereby prevent a blowback into the source of fuel.

Another object of this invention is to provide a new and novel fuel feeding device for a gas turbine having a seal which has good abrasive wear characteristics.

Another object of this invention is to provide a new and novel gravitational fuel feeding device for a gas turbine.

Qbjects and advantagesotherthan those set above "ing outwardly from one side.

2,923,575 Patented Feb. 2, 1960 2 will be apparent from the following description when read in conjunction with accompanying drawings in which:

Fig. 1 is a schematic view, partly in section, of a gas turbine power plant embodying the feeding device of this invention;

Fig. 2 is a cross section view taken along the line IIII of Fig. 1 showing the flexible member and a valve in the open position; and I Fig. 3 is a cross section view taken along the line HI-III of Fig. 1 showing the flexible member and a valve in the closed position.

A gas turbine power plant 10 is illustrated in Fig. 1 and comprises a compressor 11, a combustion chamber 12, and a gas turbine 13 operably connected together by suitable ducts 15. Air enters the compressor 11 where it is compressed and then flows into a duct 15 where it mixes with the fuel. The air-fuel mixture then enters the combustion chamber 12 where it isburned and converted to a hot gas which exhausts through the turbine 13 imparting rotary motion thereto. The fuel may be any of the suitable fuels adapted for use with gas turbines, however, powdered coal 16 stored in a bin 17has been illustrated for use in this gas turbine. A feeding mechanism 18 is provided between the source of fuel in the bin 17 and the combustion chamber 12 which is positioned in a duct 15 between the compressor 11 and the gas turbine 13.

The feeding mechanism 18 is mounted on a frame 19 and includes means for measuring and depositing a predetermined amount of fuel, herein illustrated as a star metering wheel 20 positioned immediately below the bin 17 in which the 'powdered coal 16 is stored. Although a star metering wheel is illustrated, any device for repeatedly feeding a predetermined charge of fuel may be used in the feeding mechanism of this invention. A

flexible tubular member 22 is connected to the star metering wheel 20 immediately beneath the wheel, and extends to the duct 15 in which the combustion chamber 12 is positioned. Preferably as shown the member 22 extends vertically downward to aid the flow of coal therethrough. This member 22 is provided with a relief tube 23 which exhausts to atmosphere. The relief tube 23 is preferably a flexible tube and positioned intermediate the vertically spaced extremities of the member 22. Although the relief tube 23 is illustrated and described as a flexible tube, any suitable tube having cooperating valve means may be used as the relief tube.

Valve means 26, 27, 28 are provided for collapsing and thereby sealing the member 22 and the tube 23. Valve means 26 and 27 are for controlling the flow of fuel through the member 22 and for sealing the member 22 to prevent a blowback of high pressure air from the ducts 15 into the powdered coal 16 in the bin 17. These valve means 26 and 27 arepositioned adjacent the vertically spaced extremities of the member 22. One of the valves 26 or 27 is closed at all times during the feeding cycle to seal the powdered coal 16 in the bin 17 from air in the power plant at cycle pressure. Valve means 28 acts as a pressure relief valve and is positioned adjacent the end of the relief tube 23 that exhausts to atmosphere.

The valve means comprise sliding cam rods 32,33, 34, guides 36, and means for actuating the cam rods. As shown in Figs. 2 and 3, the guides 36 are substantially rectangular in cross section and have a stem 37 'project- The stem 37 of each guide 36 has a longitudinally extending bore38 'andis positioned to extend toward one of the cam rods 32, 33, 34. The side of the guide 36 opposite the stem 37 acts as a backing plate 39 for the member 22 and the tube 23. The guides 36 are mounted on the frame 19. in an'yof the well known ways such as by mounting screws 40' a d thebores 38- ofthe-stems37 of their respective'guide's 36 so that they can be actuated in a manner hereinafter described to engage and collapse the flexible member 22 andtube 23iagainst' the backing plates 39 with sufficient force to form a seal against leakage of highpressure air in the ducts 15.

Figure 2 illustrates a section of the-flexible member 22 and the valve 26 in an openpos ti'onto permit a charge of fuel to drop from the star metering wheel into'the member 22; Fig. 3 illustrates a section of the flexible member 22 -and valve 27 in a closed position. In the closed position the member 22 is collapsed against the backing plate 39 to form a seal within the member.

The'flex'iblemember 22 and the tube 23- are preferably constructed of a rubber base material which will resist the abrasive wear caused by'the powdered coal suspended in air and which passe's'through the member 22 and the tube 23. However, any flexible material having a good abrasive-wear resistant characteristic may be used for the tube 23 and member 22 with good results; The tube 23 and member 22 are collapsed by'the rods acting against the backing plates to form a seal. This type of. seal is effective in preventing leakage of. air under the high pressures'generated by the compressor in the gas turbine power plant. A small amount of wear on the inner sides of the tube or member due to the abrasive action of the coal suspended in air passing through will not materially decrease the effectiveness of the seal because the tube and member can be compressed a little more to compensate for. the wear:

The entire feeding mechanism 18 is driven by an independently operated source-of power such as the electric motor42' illustrated in Fig. 1. The motor 42 is operably connected to the star metering wheel 20 and a cam shaft 43 by beveled gears 44. The cam shaft 43 is rotatably mounted on the frame 19 in a position substantially parallel to and spaced apart from the flexible member 22. Mounted on the cam shaft. 43 are suitable cams 45, 46, 47 positioned to operable engaging the sliding rods32, 33, 34, respectively. Resilient means, illustrated as coil springs 49, are providedfor keeping the cam rods 32, 33, 34 in constant working engagement with their respective cams 45,. 46, 47. One of the coil springs 49 surrounds each cam rod 32, 33, 34, respectively, between the end of the rod engaging its correspondng cam and the stem 37 of corresponding guides 36. These springs 49 coopcrate with the ends of the cam rods 32, 33, 34,. and the stems 37 to bias the cam rods into constant working agreement with their respective cams 45, 46, 47. The

.the valves 26, 27, 28 according to a predetermined sequence; The cam shaft 43 and the star meterng' wheel 20 are'cooperatively arranged with the beveled gears 44 to drive the feeding mechanism 18 repeatedly through the-same cycle.

The feeding mechanism. 18 ofthis invention operates in the following way. The star metering wheel 20 is continually rotating and depositing a predetermined charge of' fuel from the bin 17 into the'u'pper portion of the tubular member'22. The cam shaft 43andcams 45, 46, 47 are also continually rotating andthereby actuating the cam rods 32, 33, 34 according to the" following predetermined sequence; When the cycle begins all the valves 26, 27, 28 are closedthereby collapsing the tubular member 22 and the relief tube 23 at three separate points and forming a cavity 51 therein. The valve 26 is. then opened permitting the predetermined charge of powdered coal. supplied by thewheel 20. to. drop by gravity into the cavity 51. Valve 26 is. then closed. When valve- 26 closes valve 27 opens:permittingcthercyclepressure: of. the turbine power plant to force air under pressure into the tubular mcmber22. When thepressure inthe tubular member 22 is equal to the cycle pressure the powdered coal 16 falls down through the tubular member 22 into the combustion chamber 12 by means of gravity. A vibrator 54, such as the electrical vibrating device disclosed in US. Patent 1,005,612, may be attached to the tubular member 22 for vibrating the member 22 and I thereby aid the powdered coal 1 61 ind'ropping. through the tubular member 22' and prevent the powdered coal 16 from stickingto the sides of the tubular member 22. After the powdered coal 16 has dropped into the combustion chamber 12, valve 27 is closed and valve 28 which operates the relief tube 23'o'pens. The rel ef tube 23 opens to atmosphere and-permits the high pressure air in the cavity 51 to escape until the pressure in the cavity 51 is reduced to atmospheric pressure. When the air in the cavity 51 is back to atmospheric pressure the valve 28 again seals the relief tube 23. Valve 26 then opens and the cycle is repeated.

The described apparatus has provided for gravitational feed of powdered coal into the combustion chamber 12 and insures that blowback into the storage bin will be prevented.-

Although but one embodiment has been illustrated and described, it will be apparent tothose skilled in the art that'v'ari'ous changes and modificat ons may be made therein without departing frorn the spirit of theinvention or from the scope of the/"appended claims.

It isclaimed and desired" to secureby Letters Patent:

1''; A device for feeding fuel. into a high pressure zone of a" ga's'turbine power plant comprising a vertically disposed flexible tubular member having its lower end adaptable to be connected to said high pressure combustion zone, a source of fuel, a star metering wheel connected to the other end of said member and to said source of fuel for supplying apredetermined charge of fuel to said member; first and second cam rods positioned adjacent the vertical extremities of said member near said star meteringwheel' and said high pressure zone respectively, a flexible relief tube connected to said member intermediate saidcam rodsfor exhausting to atmosphere, a third cam rod positioned adjacent the end of said relieftube open to atmosphere, said cam rods engaging said member and said tube in alternate sealing and unsealing relation, guide means cooperating with said cam rods in sealing said tube and said member, a rotatably mounted cam shaft, cams mounted on said cam shaft and positioned to' operatively engage corresponding said camrods, said cams being formed so that corresponding said cam rods are actuated'during,a-portion-of each revolution of said cams according to a predetermined sequence, saidcams at all times maintaining at least one of said control valves in a scaling position and opening said relief valvevaftersaid second cam rod seals said member and before said'first cam rod unseals saidmembenand means for rotatingrsaid wheel and said cams repeatedly through the same cycle" whereby fuel. is fed. by gravity through said. member into said combustion zone and said source of fuel is at all times sealed from the high pressure. air in the plant;

2'. Av device'for feeding, fuel into a high pressure zone of a gas turbine power plant comprising a" vertically disposed flexible tubular member. having its lower end adaptable'to. be connectedto said high pressure-combustionzone; a source of fuel, a star metering wheel connested-to the other endof said member and to said source of fuel. for supplyinga predetermined charge of fuel. to said'member, first and second cam rods. positioncdadjacent the vertical extremities of: said member near said star metering wheel and said high pressurezonerespectively, a flexible relief tube'connected to said: member intermediate said cam rods for exhaustingto atmosphere, a: third cam rodpositioned adjacent theend of. said relief tube open to atmosphere, said cam rods engaging, said member: and said. tube-in alternate sealing and unsealing relation, means for guiding said cam rods, said" guide means having back up plates positioned adjacent said member and said tube and spaced from said cam rods for cooperating with said rods in sealing and unsealing said member and said tube, a rotatably mounted cam shaft, cams mounted on said cam shaft and positioned to operatively engage corresponding said cam rods, said cams being formed so that corresponding said cam rods are actuated during a portion of each revolution of said cams according to a predetermined sequence, said cams at all times maintaining at least one of said control valves in a sealing position and opening said relief valve after said second cam rod seals said member and before said first cam rod unseals said member, and means for rotating said wheel and said cams repeatedly through the same cycle whereby fuel is fed by gravity through said member into said combustion zone and said source of fuel is at all times sealed from the high pressure air in the plant.

3. A device for feeding fuel into a high pressure zone of a gas turbine power plant comprising a frame, vertically disposed flexible tubular member having its lower end adaptable to be connected to said high pressure combustion zone, a source of fuel, a star metering wheel connected to the other end of said member and to said source of fuel for supplying a predetermined charge of fuel to said member, first and second cam rods positioned adjacent the vertical extremities of said member near said start metering wheel and said high pressure zone respec-- tively, a flexible relief tube connected to said member intermediate said cam rods for exhausting to atmosphere, a third cam rod positioned adjacent the end of said relief tube open to atmosphere, guide means mounted on said frame, said cams being slidably mounted in said guide means, said guide means having back up plates positioned adjacent said member and said tube and spaced from said cam rods for cooperating with said rods in sealing and unsealing said member and said tube, a rotatably mounted cam shaft, cams mounted on said cam shaft and positioned to operatively engage corresponding said cam rods, said cams being formed so that corresponding said cam rods are actuated during a portion of each revolution of said cams according to a predetermined sequence, said cams at all times maintaining at least one of said control valves in a sealing position and opening said relief valve after said second cam rod seals said member and before said first cam rod unseals said member, and means for rotating said wheel and said cams repeatedly through the same cycle whereby fuel is fed by gravity through said member into said combustion zone and said source of fuel is at all times sealed from the high pressure air in the plant.

4. A device for feeding fuel into a high pressure zone of a gas turbine power plant comprising a vertically disposed flexible tubular member having its lower end adaptable to be connected to said high pressure combustion zone, a source of fuel, a star metering wheel connected to the other end of said member and to said. source of fuel for supplying a predetermined charge of fuel to said member, first and second cam rods positioned adjacent the vertical extremities of said member near said start metering wheel and said high pressure zone respectively,

a flexible relief tube connected to said member intermediate said cam rods for exhausting to atmosphere, a third cam rod positioned adjacent the end of said relief tube open to atmosphere, guides mounted on said frame and positioned to surround said member and said tube, said guides having an outwardly extending stem having a bore therein, said cam rods being slidably mounted in the bores of said stems for engaging said member and said tube in alternate sealing and unsealing relation, a cam shaft rotatably mounted on said frame, cams mounted on said cam shaft and positioned to operatively engage corresponding said cam rods, said cams being formed so that corresponding said cam rods are actuated during a portion of each revolution of said cams according to a predetermined sequence, said cams at all times ,maintaining at least one of said control valves in a sealing position and opening said relief valve after said second cam rod seals said member and before said first cam rod unseals said member, and means for rotating said wheel and said cams repeatedly through the same cycle whereby fuel is fed by gravity through said memher into said combustion zone and said source of fuel is at all times sealed from the high pressure air in the plant.

References Cited in the file of this patent UNITED STATES PATENTS 955,606 Moreau Apr. 19, 1910 1,943,589 Domina Jan. 16, 1934 2,387,923 McBrien Oct. 30, 1945 2,590,458 Prickett Mar. 25, 1952 FOREIGN PATENTS 360,943 Great Britain Nov. 9, 1931 689,486 Great Britain Mar. 25, 1953

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