When running a paper mill, one of the biggest problems that can occur is a paper break. In a mill the size of Austell Boxboard Mill #2, it can shut down production in the entire facility for up to an hour. The long production line has speed adjustment stations located at various strategic places which allow operators to adjust the speed of the line as the paper is dried. The operators were using the ‘feel’ of the paper only as a guide for how much speed to apply or reduce at each station. This method lent itself to higher than average breakage rates, especially during shift change.
Engineered Systems was able to offer them a more scientific method of speed adjustment. We did this using 9 different PLC’s monitoring 10 different zones. The PLC’s each received 1 or 2 signals from an incremental encoder. One Master PLC communicated with 9 slaves to get the speed data, and the master PLC then, in turn, was polled over Modbus by the plant’s Matricon OPC server system which could be viewed at the main monitoring station and stored the information as historical data. In addition to the plant monitoring, each PLC control panel had three displays for the speed of the section on either side of it and the draw between the two. These local displays allowed the operators to adjust speed with hard data to accompany the ‘feel’ of the paper. Since the system lacked a true digital operator interface, we also included a web server into the master PLC to allow them to adjust settings if the rollers are ever changed to a different diameter.
Some unique challenges had to be overcome to make this system work. One of the main issues was that some of the control boxes had to be close to the mill line and would be exposed to temperatures upwards of 70° C. This meant all the components had to be able to withstand these temps. After much research, we were able to find displays that could withstand the high heat, and still be legible. Another challenge was integrating the system into the existing plant DCS. Engineered Systems engineers worked together with the Austell engineers to integrate their Matricon OPC server with the individual controllers. Engineered Systems engineers tested the entire system with Matricon before it ever left their facility ensuring that the commissioning effort on the part of the customer would be minimal.
- Client Austell Boxboard Mill #2
- Date September 7, 2013
- Tags Programming & Communications, Pulp & Paper