GB974863A - Improvements relating to industrial furnaces - Google Patents

Abstract

974,863. Heating air; heating steam boilers by waste gases. WAAGNER-BIRO A.G. Dec. 1, 1960 [Dec. 1, 1959; Dec. 4, 1959; Nov. 18, 1960], No. 41306/60. Headings F4A and F4S. An industrial furnace of the regenerative type, for example a Siemens-Martin furnace or a glass-melting furnace, is provided with a separate waste heat recovery unit through which waste gases from the regenerators are passed and wherein heat recovered from the waste gas is applied to preheat combustion air to be supplied to the regenerators, to preheat feedwater and to generate steam therefrom. In the apparatus shown in Fig. 1, waste gases from a Siemens- Martin furnace 11 flow alternately through regenerators 13 and thence to a heat-recovery unit containing boiler tubes 4 in an up-pass and air-heating surfaces 2 in an adjoining down-pass. Combustion air flows through the heater 2 and is conveyed by a duct 5 to the appropriate regenerator 13. Steam is superheated at 15. In Fig. 4 the air-heating surfaces 2 and boiler surfaces 4, 15 are located side-by-side in a single vessel 1, the waste gas flow being controlled by a damper 16. In Fig. 3 (not shown), the unit consists of a waste gas main spaced along which are chambers containing the airheating and boiler surfaces, gas being diverted through the chambers by dampers disposed in the main. Fig. 6 shows a furnace 11 heated partly by burners 12 and partly by the combustion of low calorific value gas which is preheated in the outer regenerators 13. Waste gases from these regenerators and the inner air preheating regenerators 13 flows through an upright vessel containing a large superheater 15 and boiler surfaces 2. Air is heated in an adjoining vessel by indirect contact with steam superheated at 15. In a final modification, Figs. 7-10 (not shown). the waste heat unit consists of an upright vessel located beside the furnace stack and containing a bank of airheating tubes above a bank of steam generating tubes. A stack damper diverts gases through the vessel which is surmounted by an exhaust fan delivering cooled gases into the stack. Large doors providing access to the tube banks are disposed on one side of the vessel.