GB1192007A - Improvements relating to the Heat Treatment of Sheet and Web Materials - Google Patents

Abstract

1,192,007. Automatic moisture content control. MICROWAVE INSTRUMENTS Ltd. and J. BILBROUGH. Sept. 8, 1967 [Sept. 13, 1966], No.40799/66. Heading G3R. A desired moisture content is produced across the width of a travelling web by passing the web through a wave-guide which detects moisture content at a number of positions across the width and automatically controls the heating at corresponding positions across the width. In Fig. 4, a wet paper web W, moving to the right, passes a slot in a wave-guide 44 which is reciprocated continuously or step-by-step across the width of the web. A switch 36, operated by movement of the waveguide, connects the output of a microwave detector, associated with the waveguide and responsive to the moisture content of the web, in succession to a number of controllers C 1 -C 5 associated with heaters H 1 -H 5 across the width of the web so that each heater is controlled in turn to maintain a desired moisture content at its position. The heaters may be energized by gas, steam, or highfrequency alternating current. Control of the heaters is assisted by a further reciprocated wave-guide 42 detecting the moisture content of the incoming web. Further controlled heating may be provided downstream of wave-guide 44 by heaters HB which may utilize the microwave power of the wave-guide. Reciprocation of the wave-guide is by an electric or fluid-pressure motor. In a modification, the wave-guide is stationary and a number of slots, provided at different positions across the wave-guide, are associated with detectors separately connected to the controllers for simulataneous operation.