IQChargeMD - A control application for optimizing the white water charge demand

Wet end chemistry plays an important role in drainage, retention and formation - thereby affecting paper quality properties and paper machine runnability. A core factor in the interaction between fibers, fines, fillers and trash is the charge neutralization demand. The control and stabilization of the charge is an important factor in modern, efficient paper machine process management.



Description

IQChargeMD is a dynamic model-based control for managing whitewater charge level. It uses charge measurement to adjust the fixative flow. The control algorithm calculates three predictor series based on previous control actions, observed process changes and consequent model uncertainty. This triple predictor technique provides superior control performance compared with conventional dead time compensated model-based algorithms.

IQChargeMD can be used in conjunction with white-water consistency (retention) control to improve wet end stability even further.



Benefits to the Papermaker

• Improved runnability
  • Stable white-water charge level
  • Charge reversal can be avoided

• Optimal retention
  • Stable charge level creates optimal conditions for the retention chemical

• Reduced need for machine wash up
  • Stable and right level in charge means cleaner machine operation

• Easier start-ups
  • Stable adhesion to press center roll
• Chemical savings
• With steadier charge in the wet end, the dosing of chemicals can be optimized

Technical Features

• The model-based control algorithm produces three variant predictions which describe the expected range of future charge values, based on a history of control actions, responses and process uncertainties.
• Based on the model’s predictions, the control calculates the maximum control action that can be taken with certainty. This results in smooth responses to setpoint changes and process disturbances while preventing any control-induced cycling.
• Charge control can also be implemented in broke recycle and furnish supply systems.

Specifications

• IQChargeMD includes:
  • Charge control loop
  • Control picture
  • Fixative flow control application (Note! No hardware is included)
• Prerequisites:
  • Charge measurement and the status signals of the analyser connected to metsoDNA
• Applications:
  • Wood-free grades; coated or uncoated fine papers
  • Wood containing grades; newsprint, SC and LWC papers
  • Tissue
  • Paperboard