Case: Development of pH control
by Vipetec Analysis™ and Optimization
Challenge in the production process
pH fluctuations in pulp and wet end caused problems with the paper machine. With the machine there had been efforts to build pH control without success for years. pH adjustment is challenging due to e.g. its non-linearity. The chemical properties of the pulp affect how the paper web can be formed on the machine. Therefore, pH control is important.
The pH of the pulp is adjusted at the beginning of the production line, where the aim is to standardize the chemical properties of the raw material. In a wet end of the paper machine, the raw materials are combined for the actual formation of the paper (paper web). The wet end pH adjustment ensures that the chemical state of the process is correct for paper production.
The project focused on two goals:
- Improving the pH management of pulp through planning, implementation and tuning of new control solution
- Construction and tuning of wet end pH control to improve pH management
We first collected data and analyzed the operation of the process with Vipetec’s analysis tools. We then selected a control strategy, implemented it, and tuned the control loops using our optimization expertise. These were first made for the pH of the pulp and after a successful result we switched to the pH of the wet end. The control target could not be achieved with basic methods, but more advanced control methods had to be used. Previously the customer had attempted to implement control many times with no success.
We were able to build and implement a functional pH control that improved pH management significantly.