Planning, scheduling, and real time operation of a pulp mill using grey-box modeling

Name: Wipawadee Nuengwang

LCSH: Kasetsart University -- Dissertations. Ph.D. (Chemical Engineering) 2020

Classification :.LCCS: TS1176

LCSH: Kasetsart University. Department of Chemical Engineering -- Dissertations

LCSH: Pulping

LCSH: Paper mills

LCSH: Production scheduling

LCSH: Production planning

LCSH: Mathematical optimization

Abstract: The pulp and paper industry is one of the largest industrial sectors for which water and energy management is essential. In this thesis an empirical model of the Kraft pulping process is developed and used in minimization of water and energy consumption of a representative pulp mill. The pulping process was simulated by using the IDEAS software package (ANDRITZ Inc.). The optimal operation conditions will be adjusted due to variations that occur in a seasonal, weekly and daily pattern and in real-time using the Real-time optimization (RTO) technique. These different times scale represent variations in wood moisture content and electricity prices that could impact the profitability of the pulp mill. In daily operation, the variation in the price of electricity from off-peak to onpeak periods is a significant factor for the optimization. The ability to vary the rate of wood chipping to consume less electricity during peak periods and more during offpeak periods is exploited, "storing" electricity in the form of chip inventory. The moisture content of wood varies with the season and high moisture content lowers pulp throughput, and increases cost, per tonne wood processed. The production rate in each month is optimized for yearly operation to minimize annual operating cost. This uses final product inventory to buffer the moisture variation. Finally, the actual moisture content of wood is unknown at any time, and it cannot be measured and instead must be inferred from other measured variables in the plant, specifically white liquor flow. An iterative procedure to estimate the moisture content and update plant set points is used to perform real time optimization to respond to variations in wood moisture content. The pulp and paper industry is one of the largest industrial sectors for which water and energy management is essential. In this thesis an empirical model of the Kraft pulping process is developed and used in minimization of water and energy consumption of a representative pulp mill. The pulping process was simulated by using the IDEAS software package (ANDRITZ Inc.). The optimal operation conditions will be adjusted due to variations that occur in a seasonal, weekly and daily pattern and in real-time using the Real-time optimization (RTO) technique. These different times scale represent variations in wood moisture content and electricity prices that could impact the profitability of the pulp mill. In daily operation, the variation in the price of electricity from off-peak to on-peak periods is a significant factor for the optimization. The ability to vary the rate of wood chipping to consume less electricity during peak periods and more during off-peak periods is exploited, "storing" electricity in the form of chip inventory. The moisture content of wood varies with the season and high moisture content lowers pulp throughput, and increases cost, per tonne wood processed. The production rate in each month is optimized for yearly operation to minimize annual operating cost. This uses final product inventory to buffer the moisture variation. Finally, the actual moisture content of wood is unknown at any time, and it cannot be measured and instead must be inferred from other measured variables in the plant, specifically white liquor flow. An iterative procedure to estimate the moisture content and update plant set points is used to perform real time optimization to respond to variations in wood moisture content.

Kasetsart University. Office of the University Library

Address: Bangkok

Email: tdckulib@ku.ac.th

Name: Thongchai Rohitatisha Srinophakun

Role: Thesis Advisor

Name: Paweena Prapainainar

Role: Thesis CO-Advisor

Created: 2020

Modified: 2025-06-30

Issued: 2025-06-30

วิทยานิพนธ์/Thesis

application/pdf

URL: https://www.lib.ku.ac.th/KUthesis/2563/wipawadee-nue-all.pdf

CallNumber: TS1176 .W57

eng

DegreeName: Doctor of Philosophy

Level: Doctoral Degraee

Descipline: Chemical Engineering

Grantor: Kasetsart University

©copyrights Kasetsart University

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