Patent GB-917507-A (GB)
Title: Magnetohydrodynamic power generation apparatus
IPC: H02K44/08
Filed: 1960-11-03
Abstract: 917,507. Pumps and generators operating by electromagnetic interaction with fluids. AVCO CORPORATION. Nov, 3, 1960 [Feb. 15, 1960], No. 37799/60. Class 35. [Also in Group XXVI] In an electrical power generation apparatus which operates by forcing hot, gaseous, combustion products through a magnetic field, the conductivity of this gas is made as high as possible by making the combination very hot by using an oxygen-rich air supply to the combustion chamber. As shown in Fig. 3, the generator comprises a divergent duct 11 of square cross-section; coils 14, 14a to produce the magnetic field and electrodes 19, 20 to carry off the generated current. Members 17, rigidly attached to foundations 18, support the duct. Suitable electrode materials are copper, stainless steel, tungsten and carbon. Since the conductivity of a gas increases rapidly with its temperature (Figs. 4, 5, not shown), greater generator efficiency is achieved by using the gas at a very high temperature. Generator efficiency can be further increased by using very strong magnetic fields in which case, the length of the duct can be reduced to a reasonable value (Fig. 6, not shown). In a typical power generating system, Fig. 7, fuel 31 with an easily-ionizable impurity is fed into a combustion chamber 30 where it is burned with air which has been drawn from the atmosphere by a turbo-compressor 33, heated, and fed into the combustion chamber at 34. The hot conductive plasma passes from the combustion chamber to the generator 35 and, after expansion, to a preheater 32, where it transfers some of its heat to the compressed air, then flows to a steam plant 36 in which heat-exchangers use the energy of the plasma to drive steam turbines, and eventually exhausts to the atmosphere. Power from the steam turbines may be used to drive the turbo-compressor 33. In a modification, an air separator provides almost pure oxygen which is mixed with air to form oxygen-rich air which is supplied to the combustion chamber (Fig. 8, not shown). In a further modification, the plasma for the generator circulates in a closed cycle and is not expelled to the atmosphere so that an expensive, inert gas, e.g. helium and argon, may be used as the plasma (Fig. 9, not shown). A large power generating system incorporating the basic features of Fig. 7 is shown in Fig. 10. Air, drawn from the atmosphere at 98, passes to main air compressor 107, is cooled in aftercooler 108 and passes to an oxygen separator 97. Part of the air stream from cooler 108 is compressed to a very high pressure by compressors 111 and 111a, is cooled in cooler 113 and is forced back to the separator. Here this air is expanded and used to refrigerate and separate fractionally nitrogen and oxygen from the main body of air in the separator. Nitrogen is withdrawn at 115 as a valuable by-product, and the oxygen, flowing along pipe 116, is mixed with air by means of valve V to form an oxygen-rich air supply in pipe 117 (87% oxygen, 13% nitrogen). This supply is further compressed by compressors 118, 120, passes through heat-exchanger 122 situated in the exhaust flow of the generator where it is heated to a substantial temperature, and then enters the combustion chamber 94 where it burns with fuel 95. The extremely hot plasma formed in the combustion chamber is forced into the generator 90 and thence through an exhaust channel 91 where it loses heat to various heat-exchangers and eventually passes to exhaust compressor 93 which sucks the plasma from the channel and then forces it up stack 92 to the atmosphere. Water is fed to the system from pump 123 and is used in various coolers connected between points a, b, c, d &c., where heat is transferred from the air system to the water system. The heated water is recombined, flows through economizer 127, where it is superheated, flows along conduit 128 to cooling jackets 129, 130 where it is converted to steam. This steam, along with steam generated in evaporator 133, flows through a superheater 132 and then into a high-pressure turbine 99. From here it flows to reheater 136, then to reheat turbine 100, to the low-pressure turbine 101 and eventually, through condenser 139 to the atmosphere. Both turbines 99 and 101 drive A.C. generator 103 which delivers its power to conductor 104. The gas flow interaction generator delivers its power to inverter 105 and thence to conductor 106. The reheat turbine generates sufficient power to drive all of the supplementary compressors. Suitable fuels for combustion are coal, natural gas or oil and a slag trap 142 is included in the duct.- Peak power demands are handled by storing excess oxygen, produced during periods of low demand, to relieve the air separator during periods of high demand. The overall efficiency of this power plant is 47.5%.