Microcomputer-based control of tobacco curing

A low-cost computer system for process control and data acquisition in curing bright leaf tobacco was designed, constructed, and evaluated. The system provides programmed control of curing environment, records process data, and allows remote inquiry and control. It was developed and tested on a six-unit experimental curing system which is part of the curing research facilities of the Oxford Tobacco Research Station, Oxford, North Carolina. Up to six alternative curing schedules, each prescribing a different desired air temperature and humidity schedule for curing, may be defined. These schedules can be modified interactively when the conditions of the incoming tobacco charge warrant changes. Automatic control of the heaters and dampers is provided based on the measurement of dry-bulb and wet-bulb air temperatures within the curing environment and making adjustments to conform to the prescribed schedule. Process data is averaged over 30-min periods and stored for later review. The system base materials cost was approximately $2000 plus about $400 per curing unit for up to 8 units per system.