GB1299213A - Improvements in and relating to generators for generating working fluids for external combustion engines and methods of generating such working fluids - Google Patents

Abstract

1299213 Gas turbine plant and combustion chambers; external combustion engine plant GINTER CORP 17 March 1970 [18 March 1969] 12791/70 Headings F1G F1L and F1S [Also in Division F4] In a combustion chamber for generating combustion products to drive an external combustion engine the supply of fuel to the chamber is controlled in response to working fluid pressure in or adjacent the chamber and a vaporizable non- combustible liquid is injected into the combustion products remote from the point of fuel injection, the liquid injection being controlled by means sensing the temperature of the working fluid. In Fig.1 the combustion chamber 30 is defined by a tube 34 having a fire tube 31 at one end into which fuel is injected by a nozzle 36. A thermally lagged casing 3 surrounds the combustion chamber 30 and also contains the cylinders 20, 21 of a reciprocating engine driven by the combustion products and connected via a crank-shaft 10 to a reciprocating air compressor 22. The latter draws its intake air from atmosphere via pipe 67 and non-return valve 68 and after compressing the air substantially adiabatically delivers via non-return valve 26 and passage 27 to an air reservoir 28 separated from combustion chamber 30 by a wall 29. Holes 32, 35 in wall 29 and holes 33 in fire tube 31 permit compressed air to flow into and around the combustion chamber and fire tube. Water spray nozzles 40 are directed towards the outlet end of combustion chamber 30. The plant is started by an electric starting motor which rotates crank-shaft 10 until the compressed air in chamber 30 exceeds the self ignition temperature of the fuel, whereupon the starter is automatically cut-out and a crank-shaft driven pump 48 delivers fuel past a throttle valve 38 to injector 36 for substantially stoichiometric combustion with the air. Valve 38 is controlled by a solenoid 65 in response to combustion chamber temperature as sensed by thermostat 62 in such manner that fuel injection is prevented unless the temperature exceeds that for self ignition. Valve 38 is also controlled in response to combustion chamber pressure so that fuel injection only takes place when the pressure has fallen below a predetermined minimum. Control of the fuel supply is described below in greater detail with reference to Fig.11. Should the temperature of the combustion products leaving chamber 30 exceed a predetermined maximum as sensed by a thermostat 61 then the latter causes solenoid 63 to open valve 42 so that pump 44 forces water from tank 47 through nozzles 40 into the combustion products which are thus cooled. The water is converted into steam and increases the mass of working fluid occupying casing 3. Admission of working fluid to engine cylinders 20, 21 is controlled by a slide valve 51 formed as a ported tube dimensioned to cover one or other of cylinder head ports 23, 24 in accordance with the position of crank-shaft 10 which is linked to slide valve 51 by a bell-crank 52, push rod 53 and cam 55. Admission of working fluid to the interior of slide valve 51 is controlled by a further slide valve 60 fitting around ports in slide 51. The position of slide 60 is controlled by a bellows type pressure sensor 57 which moves the slide 60 to admit working fluid to slide 51 and cylinders 20, 21 whenever the pressure in casing 3 falls below a predetermined minimum to thus drive compressor 22 to restore the pressure. Sensor 57 can be over-ridden by a manual lever 58<SP>1</SP>. Power is taken off from the crank-shaft 10 at 71. In a modification the engine can have more than two expansion cylinders 20, 21, there being twice as many expansion cylinders as there are compressor cylinders 22. The pistons may be double acting and the compressor may be geared to the crank-shaft 10. In a further modification the combustion chamber may be formed as one of the cylinders of a multi-cylinder engine block by eliminating the piston therefrom and providing air and fuel inlets at one end and water injection at the other end. In this case an auxiliary compressed air storage chamber may be provided. In a further arrangement the reciprocating engine of Fig.1 is replaced by a turbine. Fig.2 shows a modified combustion chamber 75 having a cylindrical metallic body 76 surrounded by lagging 80. The fire tube 31 is surrounded by tube 34, as in Fig.1 and by an intermediate tube 31<SP>1</SP>, the air-flow from chamber 28 to the concentric passages defined by the tubes being in specified proportions. Fuel is controlled as described below with reference to Fig.11. Thermostat 61<SP>1</SP> controls water injection through nozzles 87. A safety valve 113 and rupture disc 114 are provided together with a manually settable valve 91 controlling the flow of working fluid to the expansion engine, the valve 91 having an over-riding control linked to a pressure sensor 115 so that a drop in pressure in combustion chamber 75 causes an increased opening of valve 91 to increase the flow to the engine. The fuel supply system shown in Fig.11 comprises a pump P supplying fuel through line 82 to an injector 79 directed into fire tube 31, control of fuel by-passed back through line 82<SP>1</SP> to the fuel tank being effected by a needle valve 98 co-operating with seating 97<SP>1</SP> and forming part of a control unit 100. The latter includes a chamber 96 connected to air reservoir 28 via lines 84, 94 and a further chamber 93 which can be communicated by 3-way valve 85 either to line 108 leading to atmosphere or to air reservoir 28 via pressure reducing valve 91<SP>1</SP>. Prior to the air temperature as sensed by thermostat 62 being sufficient for self ignition of the fuel, actuator 65<SP>1</SP> sets valve 85 to the position in which chamber 93 is vented to atmosphere so that the pressure in chamber 96 holds needle 98 away from seat 97<SP>1</SP> against the force of spring 104<SP>1</SP> to permit all the fuel supplied by pump P to be by-passed back to the tank. When the self ignition temperature is reached, actuator 651 turns valve 85 to communicate chamber 93 with the pressure downstream of reducing valve 91<SP>1</SP> thus causing an increase in fuel pressure in line 82 as needle 98 moves towards seat 971 and the by-pass is reduced. When the fuel pressure exceeds a minimum determined by the setting of spring 104 needle valve 99 of injector 79 is forced to the right permitting the fuel to flow to fire tube 31. Any subsequent variation in air-pressure within reservoir 28 causes movement of needle valve 98 and consequent variation in the fuel injected.