| 摘要 |
1,248,817. Alumina. F. E. CONTI. 29 May, 1969 [3 June, 1968], No. 27247/69. Heading ClA. [Also in Division F4] An installation for production of electric power with double heat recovery and comprising a partial recovery electric power station combined with a Bayer process alumina plant includes (1) a first heat-exchanger in which feedwater for a steam generator of a turbo-alternator is heated by thermal exchange with a fluid, e.g. water, after the fluid has been passed in heatexchanging relationship with the mass obtained on completion of a hot caustic alkali/bauxite reaction; (2) a second heat-exchanger in which generator feed water is heated by hot water discharged by an evaporating assembly which concentrates the caustic alkali solution. In one embodiment (Fig. 1), bauxite is treated in reactor 10 with NaOH (at least 30‹ BaumÚ) at 180-230‹ C. using steam fed in at 13 from the medium pressure stage 22 of the turbo-alternator. Exhausted lye, after separation from red mud, enters evaporator 14 at 15 and issues in concentrated form at 16 for recycling, via line 12, to reactor 10. Condensed steam from evaporator 14 heats feed water to generator 20 by exchange at 29, and then returns to condenser 24 via line 37. A second stream of generator feed water in line 26 is heated in exchanger 28 by fluid circulating in line 35 and coil 34 located in reactor 10. The temperature of the reaction mass is reduced to less than 100‹ C. by the heat-exchange fluid. The streams of heated feed-water in lines 30, 31 are combined at 32 before entry to generator 20. In a further embodiment (not shown) water reservoirs are provided upstream and downstream of heat exchanger 28, further heat-exchangers in series with exchanger 28 are provided to further preheat the generator feed water by steam drawn from the medium and low pressure stages of the turbo-alternator, and a de-gassing appliance inserted in the generator feed duct feeds steam to a set of heat-exchangers fed by steam drawn from the high and medium pressure stages of the turbo-alternator. Instead of the generator feed stream (from condenser 24) being divided, as in Fig. 1, heat exchangers 28, 29 may be arranged in series so that the feed stream passes through them successively. |
