Retrofit design methodology based on process and product modeling

The Canadian pulp and paper industry currently faces many challenges. Competition from mills in countries with low production costs and advantageous economies-of-scale, the increasing price of energy, increased fibre costs and currency exchange rates, amongst others, are making it increasingly difficult for Canadian pulp and paper companies to survive in the global market place. Moreover, due to its energy-intensive nature, the industry has a large environmental footprint that needs to be dealt with. This requires the industry to rethink its strategic goals and consider sustainability in order to survive and prosper into the future.; The implementation of data and information management systems at pulp and paper mills have made available massive amounts of process, cost and environmental data. The effective use and availability of these data have increased insight into the production and business processes at pulp and paper mills. It has also been established that these data have not been fully exploited and as such, there is room for improvement. Retrofit process design is one of the fields that may reap the benefits of improving the use of the available data.; The objective of this thesis is to develop a methodology for retrofit design decision making that uses process, cost and environmental data available from information management systems and extracts information and knowledge from them through the application of process systems engineering tools. The methodology is applied in a case study that considers the increase of de-inked pulp production and implementation of cogeneration at an integrated newsprint mill.; The methodology uses a new, bottom-up approach whereby process and cost data are first used at the process level in order to characterize the existing mill as well as the retrofit design alternatives. This is done by applying an operations-driven cost modeling approach that was developed as part of this work. The resulting cost model is able to synchronize the process and cost flows along the process.; The results show that the cost model is a versatile tool for evaluating the manufacturing operations of the design alternatives by means of marginal cost analysis and analysis of operational strategies. Next, the process and cost information obtained from the cost model is used at the supply chain level using supply chain and life cycle assessment models in order to determine both economic and environmental consequences. By expanding the system boundaries beyond the mill fence, more sustainable alternatives may be identified. The results show that the best performing alternative at the process level is not necessarily the same at the supply chain level. Furthermore, scenario analyses give further insight with regards to the economic and environmental performance of the alternatives under different market conditions. Finally, a multi-criteria decision making panel is carried out in order to systematically evaluate the design alternatives, establishing the preferred one based on selected process- and supply chain-level criteria. Specifically; the panel members were asked to weight the criteria using a trade-off method. The result of this panel indicates that the use of both process- and supply chain level criteria leads to a different decision than would be expected by only using a single economic criterion such as profitability, as is usually done in conventional techno-economic studies. The complete methodology thus transforms process-level data into process- and supply-chain level information and knowledge for retrofit design decision making.; Future work includes the establishment of sensitivity- or risk-based process- and supply chain-level metrics, so as to capture the variation in design parameters and market conditions. Furthermore, social considerations need to be included in the analysis to enable the decision makers to make sustainable decisions.