Process control of milk pasteurization using Geothermal brine under Geothermal brine temperature and flow rate disturbance

Abstract

Geothermal brine can be used as a heating liquid for pasteurization unit either by directly use the brine to heat up the raw milk, or by heating secondary fresh water. The geothermal brine can be obtained directly from geothermal well or from geothermal power plant separator. Unlike conventional pasteurization, the flow rate and temperature of geothermal brine might fluctuate due to many factors such as rain, well decline, and well shut down. Inherently the geothermal reservoir tends to decline in pressure and temperature. If the geothermal brine is obtained from geothermal power plant, then the flow rate and temperature of geothermal brine itself is susceptible to many changes in plant’s operation. A control system is needed for such utilization of geothermal brine. Simulation has been carried out to study the effect of PID feedback controller under geothermal brine temperature and flow rate disturbance. The result shows that PID controller could be used to compensate such disturbance. The PID controller controls milk inlet flow rate to balance the effect of both disturbances.