One of the many pilot plant processes currently under development by
chemical company, Nalco, uses a continuous reactor that is loaded from
multiple feed-points via pumps. Hitherto, the reactant flow rates were
checked by placing them on precision balances and then manually recording
the rate of change of weight. Plant operators were constantly making flow
calculations and manually adjusting the pumps to maintain the required
rates - a tedious and error-prone method. Nalco decided to streamline the
process by integrating a SCADA system, and National Instruments' Alliance
Programme member, Vista Technology was asked to design and supply the
system, based on NI's Lookout HMI/SCADA software and FieldPoint
distributed I/O.
The entire process is now viewed via customised 3D graphics. The balance
weight readings are fed into Lookout using the Lookout ASCII object,
while the feed pumps are controlled via PID functions within the
software. Each pump has a PID control panel, allowing choice of manual or
automatic modes, as well as set point adjustment and P, I and D parameter
selection. A utility screen is provided for setting alarm levels,
starting and stopping the automatic data logger and setting the frequency
of data logging. Nalco reports a significant increase in the speed and
efficiency of this project since the SCADA installation.