Patent GB-650537-A (GB)
Title: Improvements in or relating to coal-fired engines
IPC: F02C3/26
Filed: 1947-08-06
Abstract: 650,537. Gas turbine plant. BITUMINOUS COAL RESEARCH, Inc. Aug. 6, 1947, No. 21368. Convention date, Aug. 17, 1946. [Class 110(iii)] [Also in Groups II, XII, XIII, XXX and XXXI] In a gas turbine plant using powdered coal, comminuted coal is entrained by compressed air. The pressure is substantially reduced by passing the mixure through an expansion nozzle and the reduction in pressure causes the coal particles to burst. The resulting fine powder is carried by the entraining air to the combustion chamber. In a plant as arranged for a locomotive, Fig. 12, coal stored in a bunker 100 is fed by a screw conveyer to a grinder 140. The coal is carried pneumatically through a pipe 142 to one or a pair of pressure hoppers 200. From the hoppers, the coal is fed by conveyer screws 252 and delivered into a highpressure air and fuel pipe 224. At 230 the air is expanded to the low pressure of the combustion chamber and the coal is pulverized. The air and fuel pass to the burner 334 of a combustion chamber 300. The main air supply for this chamber is supplied by a compressor 500. A compressor 520 drawing from the delivery of the compressor 500 delivers high-pressure air through pipe 524 to the air and fuel pipe 224. The combustion products pass through a bank 370 of cylone separators to a turbine 400. The turbine drives the compressors and an electric generator 600. The turbine exhaust passes through a heatexchanger 700 by which the combustion air is heated. A steam boiler may be combined with the heat-exchanger and provide steam for train heating. Coal bunkers. The. bunkers are substantially sealed by the doors 106, Fig. 6, and may have one or two converging portions 114, 116 from which the coal is taken by conveyer screws 126. The screws are driven by air motors 528 taking air from the high-pressure pipe 524 and discharging into a pipe 532 by which turbine exhaust gas is led to the bunkers for heating and drying the coal. The cavities 120 may be used for storing water. Pressure hoppers. Hoppers 230A, 230B. Fig. 14, operate alternately. As shown, comminuted coal from hopper 230A is being delivered by screw 252 through valve 264 into the box 260 and the high-pressure air pipe 224. The interior of the hopper is connected to the box 260 by pipe 270 and valve 274 and is sealed at valves 233 and 284. Hopper 230B is being filled with coal through valve 235 and is sealed from the high pressure in box 260 by the closed valves 266 and 276. Comminuted coal from the grinder 140 is carried by air stream to pipe 242 and is delivered to a cyclone seperator 240. The cleaned air goes out by the central pipe 246 and is drawn off by a centrifugal pump which acts as a further separator. In place of the cyclone 240, a cyclone may be embodied in the upper part of each hopper. Pneumatic pulverizer. In the form shown in Fig. 20, comminuted coal is fed by a screw 255 into the high-pressure air pipe 250. The air and coal expand in a nozzle 262 with a pressure drop of, say, 80 lbs. per sq. inch and the coal is pulverized in the expansion. The nozzle is revoluble and is inverted when it becomes choked. This may be done automatically by a motor 270 brought into action by the equalizing of the pressures in the lugs of the manometer 272 when the air flow ceases. The nozzle may have equal converging and diverging portions. The expansion nozzle may be situated anywhere in the high-pressure air pipe, as at 230 in Fig. 12, or at the entry into the combustion chamber. Combustion chamber. Air from the main compressor 500 is divided at the end of duct 350, Fig. 15, by a flange 332. Air passing above the flange enters the flame tube 330 between swirl vanes 353 and supports the combustion of the pulverized coal delivered tangentially by a pipe 250 into a burner 334. A sparking plug 336 is provided. The air passing below the flange 332 passes between swirl vanes 353, descends around the flame tube and mixes in space 324 with the combustion products. The gases are cleaned in a bank 374 of cyclone separators and pass by a duct 375 to the turbine. The wall 300 has a lining 318 of heat resisting steel, an insulating layer 316 and an outer shell 314. The burner may have a pilot fuel jet. In an alternative form, Fig. 18, the expansion nozzle 255 is placed at the entry to the combustion chamber. The pulverized fuel and air are delivered to the chamber 366 through a tangentially arranged injector 368 and residual large particles are broken up by impact with the chamber wall. The mixture is heated by hot gas drawn by the injector from the discharge duct 317 of the combustion chamber through a pipe 315 and a jacket chamber 361. The heated fuel passes down a central tube 367 and is burnt in the chamber 345. Air from the main compression enters the chamber between swirl vanes 346. The swirling motion of the gases separates cut the solid particles, which are removed at 331, and the cleaned gases pass under a baffle 323 to the outlet pipe 317. Steam generators. A tubular boiler with upper and lower drums 720, 730, Fig. 25, may be built in or associated with the exhaust heat-exhanger 700. The lower drum 730 may be provided with a flame tube 732 or a ring of electric heaters 734 which are brought into action automatically by a device 736 when the steam pressure falls unduly. Plant control. Power is regulated by controlling the fuel supply. This may be done directly by controlling the speed of the motor 254, Fig. 12, which drives the feed screws 252, or, by means of a byepassing arrangement in the high-pressure air pipe 224. In this case, regulation is effected by a throttle valve 290 which, with a constant flow of coal laden air in the pipe 224, determines the amount that goes through the valve and the amount that is diverted to a cyclone separator 292. That which goes to the cyclone is separated; the coal dust being returned to the hopper by a pipe 294 and the air to the pipe 224 by a pipe 291. Automatic weighing devices 296 may be built into the hoppers and a fuel meter 225 put in the pipe 224 with indicating instruments in the locomotive cabin. Locomotive lay-out. Two separate plants may be placed in line with coal bunkers between them. A single plant or two placed side by side may have the coal bunkers at one end or bunkers at each end. Specification 591,921, [Group II], is referred to.