Improvements on Model Predictive Control for a Pulp Mill Process

A nonlinear optimal control approach for the pulping process of paper mills

“…The significance of the aforementioned state variables and control inputs is as follows [1–5]:…”

“…The multi‐stage mechanical pulping process comprises the following stages [1–5]: (i) wood chip pre‐treatment, (ii) wood chip refining, and (iii) pulp refining. In the wood chip pre‐treatment stage, wood chips are screened to remove over and under‐sized particles and next they are heated and steamed at a temperature of about 100°C.…”

“…Another quality indicator is the pulp consistency which stands for the ratio of the mass of dry fibres over the sum of the total mass of dry fibres and of the water suspension. When this ratio is between 20% and 50% the pulp is considered to be of high consistency, while when it ranges between 3% and 5% the pulp is considered to be low consistency [1–5].…”

“…The mechanical pulping process is among the most energy intensive processes in industry [1–5]. Paper is an important commodity, and the demand for paper of various types and quantity grows steadily [6–10].…”

An Approach for Feedforward Model Predictive Control of Continuous Pulp Digesters

“…According to the simulation results, MPCs based on both linear-and nonlinear-fundamental models provided a better closed-loop response in comparison to the linear-empirical model, while all of them were proficient at rejecting the stochastic composition disturbances. A relatively recent work by Luppi et al [35] compared a centralized MPC strategy against a decentralized PID control strategy to evaluate the global dynamic and economic performance of a Kraft pulping mill. The authors reported remarkable economic improvements compared with decentralized control by employing an MPC for the digester and limekiln zone.…”