The Autonomous Mill: Utilizing Digital Twins to Optimize the Pulp & Paper Mill of the Future

EasyChair Preprint 14520

Abstract

This paper describes the Autonomous Mill of the future as a mill that benefits from the use of a Digital Twin utilizing a process model coupled with a control model of the real-time control system to allow the mill to run itself  with little or no human intervention.
This paper gives an overview of the equipment common to a pulp & paper mill & examples of specific opportunities where control systems optimization, Advanced Process Control (APC), and Model-Based Predictive Control (MPC) increases production; reduces costs, & autonomously operates the mill of the future. 
A pulp and paper mill can be divided into six islands of automation: raw material receiving & preparation (woodyard), pulp mill, powerhouse, paper mill, converting & finishing, & effluent treatment. Each of these islands presents their own, unique set of unit operations; and you can see similar unit operations in other industries. For example, the powerhouse equipment, besides the main difference being that the fuel is “black liquor”, the same equipment can be found in any industrial power plant. In the paper machine “island”, the use of cascaded variable-speed drives to control the paper sheet tension is also seen in the draw line of a steel, textile, or fiber mill. And, as a final example, the effluent treatment facility of a paper mill has the same equipment you will find in a municipal water/wastewater plant. 
Several examples of specific control systems optimization included for each of these “islands” include chemical savings in the lime kiln and causticizing, pulping, screening and refining, washing, and bleaching processes of the pulp mill; energy savings in recovery boiler sootblowing and the lime kiln, pulp stock preparation including cleaning and refining and the paper pressing and drying sections of the paper mill; and the environmental savings involved in effluent treatment and recycling water.

Keyphrases: Advanced Process Control (APC), Automation, Autonomous Mill, Digester, Digital Twin, Dilution Factor, Freeness, Headbox, Kappa Number, Model-Based Predictive Control (MPC), P&ID, Refiner, Screening, Sootblower, basis weight, black liquor, bleach plant, causticizer, consistency, control loops, evaporators, green liquor, lime kiln, modelling, optimize, paper, pulp, recovery boiler, virtual plant, washing, white liquor, woodyard

@booklet{EasyChair:14520,
  author    = {Brad Carlberg},
  title     = {The Autonomous Mill: Utilizing Digital Twins to Optimize the Pulp & Paper Mill of the Future},
  howpublished = {EasyChair Preprint 14520},
  year      = {EasyChair, 2024}}