During the design of an expansion to the fermentation facilities at Pabst's Neward Plant, the author found that for new installations of fifty tanks or more, computer control would be less expensive than a minimum system of local pneumatic temperature controllers. The main functions of the system were to sense the temperature of each tank, permit operator interaction with the system, provide a printed record of system operations and operate coolant valves to implement the temperature control strategy. Furthermore, it was found that considerable savings could be made if the elements of the system were purchased direct from the manufacturers and if a local software company wrote the program. The paper describes the hardware constituents of the system in detail. The system has nine control routines the most interesting of which are the FV control one, the FV operating one and the Automatic cool down routine. In the temperature control routine each hour is subdivided into twelve six minute periods. Based on a proportional temperature controller the computer calculates for how many minutes in the period should the coolant valves be open and nominates which tanks should be cooled so as to keep the cooling load constant. In directing fermentation operations, the operator responds to a series of questions posed by the computer concerning the present state of the tank and what is to be changed. The main choice in this routine is whether to bring a tank on line or to take it off. The automatic cool down system has the capability of changing the temperature set point of a tank according to a pre set schedule. The times and temperatures are loaded as soon as the operator tells the system what brand is in the tank. In conclusion, the author outlines other areas of potential computer application and illustrates some of the control routines mentioned with photographs of the video terminal for the FV control system.
Keywords: brewing computer fermentation process control