Patent GB-781427-A (GB)
Title: Improvements in or relating to gas turbine engines
Inventor: THORN JAMES DOUGLAS
IPC: F02C3/20
Filed: 1954-04-24
Abstract: 781,427. Gas turbine plant. RUSTON & HORNSBY, Ltd. April 25, 1955 [April 24, 1954], No. 11883/54. Class 110 (3). A gas turbine engine in which powdered fuel is fed to a combustion chamber by being fluidized in an atmospheric fluidizing column and a pressurized fluidizing column in series and in which the supply of fuel is regulated by the engine speed has the supply of fuel from the atmospheric to the pressurized fluidizing column regulated by a valve actuated by a piston in a cylinder, the cylinder being permanently connected at its top end to an oil pressure line and having at three different heights drain connections. Peat from a de-watering press (not shown) is fed to a disintegrator 11, Fig. 1, and then passed to a rotary louvre drier 12 where it is dried by the gas turbine engine exhaust fed through a conduit 13. The peat leaving the drier 12 falls on to a rotary table 15 where it is divided into two parts, one part being led to the mix back conveyer 16 and returned to the de-watering press and the other to the conduit 17 leading to the air-swept grinding machine 19. The relative sizes of the two parts is controlled by the position of the adjustable blades 18. On leaving the grinding machine the pulverized fuel is separated from the carrying air in a cyclone 21 arranged on top of an atmospheric fluidizing column 22 which acts as a storage vessel. From the column 22, the fuel is pumped by means of a peat pump 23 and a high-pressure air supply 24 through a conduit 25 to a small cyclone 26, arranged on top of a pressurized fluidizing column 27, which separates the high-pressure air from the peat. From the column 27 the peat is delivered from a valve 28 and conduit 29 to the combustion chamber 30 of the gas turbine plant. The high-pressure air from the cyclone 26 is led through the conduit 32 to the combustion chamber. The fluidizing air for the column 27 is taken from the gas turbine compressor 34 through a booster fan 35. Air from the same source is used to convey the fluidized peat from the control valve 28 into the combustion chamber 30. The control valve 28 is controlled by an engine speed responsive governor 38 through an oil pressure line 39. The level of fluidized fuel in the pressurized column 27 is maintained between lower and upper limits determined by probes 40, 41. These probes are connected to a double-acting relay 42 operating a solenoidactuated valve 61. When the level of the fuel reaches the upper probe 41 the relay 42 is actuated to open its contacts and thus open the valve 61. These contacts remain open until the level falls below the lower probe 40. The flow of fuel from the atmospheric column 22 to the pressurized column is controlled by a threeposition valve 43, Fig. 2, consisting of a valve member 45 connected to an operating piston 44 subject permanently to the oil pressure in a line 48. At three different heights in the cylinder wall are drain connections 49, 50, 51. If the solenoid valve 52 controlling the drain connection 49 is open the piston 44 will be in its uppermost position and the fuel supply cut off. If the valve 52 is closed and the valve 61 controlled by the probes 40, 41 open, the piston 44 will be stopped at an intermediate position in which a small aperture 54 in the valve member 45 permit a restricted flow of fuel. If both valves 52 and 61 are closed the piston moves to its lowermost position and a large aperture 55 permits a full flow of fuel. The supply of fuel to the atmospheric column 22 is controlled by the height of the fluidized bed in that column as measured by the static pressure difference between the space above and the bottom of the bed. This pressure difference actuates a diaphragm controlling a servomotor which actuates the adjustable blades 18. To avoid velocity variations in the supply of fluidizing ir to the pressurized column 27 a self-regulating throttle valve 62 is arranged in the conduit 61<SP>1</SP> upstream of a venturi 63. The pressures at the throat and downstream of the venturi actuate a diaphragm 66 controlling through a valve 67 the throttle valve 62. The valve member 45 may be operated in accordance with the pressure drop of the fluidizing air through the bed of the pressurized column. Specifications 781,428, 781,429, 781,430 and 781,431 are referred to.