UNIVERSITY OF CALIFORNIA
Department of Viticulture and Enology
WINE TECHNOLOGY AND WINERY SYSTEMS
22. WINERY PROCESS CONTROL AND INFORMATION MANAGEMENT
In the general field of process control and information management, there are
really three types of systems that are in use in industry.
These are process control
systems, data acquisition systems, and data management systems.
For systems that are
commercially available, there may be some functional overlap that blurs this distinction
(i.e. some process control systems may also acquire and save data).
However, for the
purpose of this discussion, these three types of systems will be discussed separately.
PROCESS CONTROL SYSTEMS
A process control system is a system used to control the action of equipment
within some predetermined guidelines or setpoints.
Examples of this control would be
temperature control on a fermentor, flow rate control on a pumping system, or fill level
control on a bottling machine.
In general, for any control system (or individual “loop”),
there must be a signal coming from a sensor, a setpoint with which to compare it, a
manipulated variable that can be used to return the value to the set point, and a controller
to compare the actual value with the setpoint and manipulate the manipulated value.
Using the temperature control example, the sensor would be some sort of temperature
sensor (e.g. a thermocouple or RTD), the setpoint would be the desired tank temperature,
and the manipulated variable with the position of a flow control valve that allows coolant
into the jacket of the tank.
There are four types of “signals” in a control system.
These are analog input,
analog output, digital input, and digital output.
means that the signal is a
continuous value (e.g. temperature, pressure, pH, flow rate, etc.).