GB1506725A - Oven systems - Google Patents

Abstract

1506725 Drying oven; burning waste gases ROPER CORP 22 April 1975 [25 April 1974 6 Nov 1974] 16679/75 Headings F4G and F4B An oven system, Fig. 1, e.g. for the primer and finish coat ovens for painting steel sheet, comprises an elongate housing 14 having a heating zone and inlet and outlet for the steel 12, means for maintaining the air leakage inwardly through the inlet and outlet at a predetermined level, hot air supply means 16 communicating with the heating zone, an exhaust 18 for removing gases from the zone, an incinerator 20, see Fig. 7 (not shown), for burning the gases, and means, including a heat exchanger 28, for supplying the heat produced to the means 16. Oven heating and exhaust system (Fig. 2a).- The hot air is supplied from a header 34 and ducts 36 to slots 40 in transverse ducts 38, and the hot air is recirculated by blowers 52 to ducts (64), see Fig. 3 (not shown), which communicate via headers 57, 59 with apertured cross pieces 60, 62. The air is removed by blower 48, and air leakage at the inlet is controlled by air jets 70, 72, 74, 76, Fig. 5, formed by recirculating air from the seal chamber, Fig. 2. At the exit of the oven, Fig. 2b (not shown), control air is delivered to the exhaust chamber from a supply (110). Automatic controls.-The system incorporates several temperature-responsive and pressureresponsive controls. Thermocouples 42 in the heating zone actuate dampers 44 in the ducts 36, Fig. 2, and thermocouples 100 in a chamber 98 between the seal chamber and the exhaust vestibule actuate dampers 94, 96 in lines 82 to the jets 72, 76, Fig. 5. The incinerator 20 has an automatic feed supply control (126, 124), Fig. 7 (not shown), and in a preferred embodiment, see Fig. 10 (not shown), the heat-exchanger 28 comprises two pebble bed regenerators used alternately, the temperature being regulated by the pressure in the hot gas line (134). In a modified system, the fuel supply to the incinerator is automatically controlled in response to the mass flow rate of the exhaust gases using a mass flow calculator (164), see Fig. 8 (not shown), connected to the duct 50, Fig. 2a, and a thermocouple (166) in the incinerator controls the concentration of combustible vapours in the oven, see Fig. 9 (not shown), by regulating the hot and cold air supply to the oven (dampers 44b, 160).