| 摘要 |
1,029,490. Boiler feedwater heating and supply systems; heating air for combustion. G. & T. WEIR Ltd. Dec. 31, 1963 [Jan. 3, 1963; Feb. 26, 1963], No. 51331/63. Headings F4A and F4B. Waste gases from a high-pressure boiler flow through a duet 1 in which is disposed a coil 2 through which water is pumped by a pump 4 drawing water from a flash evaporator 6, the heated water returning to the evaporator 6 through a line 5 to flash into steam which passes through a pressure control valve 20 and a line 7 to a condensing heat exchanger 8 wherein it heats combustion air for the boiler or, in a modification, feedwater, flowing through the lines 9, 10. Non-condensible gases are vented at 21 whilst condensate is extracted by a pump 12 and returned to the evaporator 6. Part of the condensate may be extracted through a line 13 and demineralization plant 15 for use as make-up water for the boiler, this part being replaced in the circuit by water fed to the evaporator through a line 16 and demineralization plant 18 under the control of a valve 19 actuable to maintain a constant level in the evaporator. The pressure in the evaporator and hence the temperature of the water entering the coil 2 is controlled by the valve 20 so that condensation of corrosive vapour on the coil 2 is avoided. In a modification, two heat exchanger coils are arranged successively in the waste gas stream and are temperature controlled to give the optimum heat regeneration whilst avoiding surface corrosion. |
