GB1419903A - Paint line oven assemblies - Google Patents

Abstract

1419903 Drying painted metal strip HUNTER ENG CO Inc 22 Jan 1974 02973/74 Heading F4G A closed loop, inert atmosphere, paint line oven assembly for evaporating paint solvent from painted metal strip 16 comprises an enclosed oven 10 through which, in use, the painted strip 16 passes, a heat source 12 comprising an enclosure 60 having means, e.g. burners 64 or electric arc, therein for generating heat, an intake conduit 40 connected into the enclosure 60 downstream of the heat generating means and a blower 28 having an intake duct 32 and an outlet duct 26, the outlet duct 26 discharging into the oven 10 and the intake duct including a first branch 34 connected to the oven 10 and a second branch connected to the intake conduit 40. A discharge duct 70 is connected at one end to the blower outlet 26 and at the other end to the enclosure 60 upstream of the heat generating means. A valve 72 is provided for deflecting a portion of the blower output into the discharge duct 70 whereby a portion of the oven atmosphere laden with solvent vapour is exhausted through the discharge duct into the enclosure. Means are associated with the enclosure for introducing a quantity of fresh air into the interior thereof, which quantity, in use of the oven assembly, is just sufficient to combine with the solvent vapour and cause combustion thereof. Heat exchange means 38, 50 are mounted in the intake conduit for removing heat, if required, from the hot gas drawn from the enclosure 60. As shown the heat exchange means comprises a coil of pipe 50 containing flowing water, the flow being under the control of a valve 56 which is in turn controlled by the output of a thermocouple 58 in the intake conduit downstream of the heat exchange means. The heat exchange means may comprise an air cooled radiator. A valve 42 in the intake conduit is controlled by the output of a thermocouple 46 in the oven. More air then as required for combustion of the burners 64 is passed therethrough so as to allow the solvent in the circulating gas to completely burn. In a modification (Fig. 2, not shown) a separate burner for burning the solvent vapour is mounted in the enclosure upstream of the heat generating means. The output of the heat generating means is controlled by the output of a thermocouple placed in the enclosure downstream of the heat generating means. Since the gas leaving the enclosure is at a constant temperature a fixed amount of heat has to be taken therefrom by the heat exchange means and thus the valve controlling the flow through the heat exchange means is manually controlled as the setting thereof during a run of the oven assembly is fixed depending upon the temperature of the cooling fluid. A valve in the discharge duct is controlled by the output of a thermocouple placed between the solvent burner and the heat generating means.