Multi-Objective-Decision-Support for process integration in recycling cascades
(Themenfeld B.2)

– Resource-efficient production within the paper- and wood pulp industry by means of a sophisticated linkage of material and energy flows between single production processes –

A main component within the process of papermaking is wood pulp, which mainly consists of cellulose and is mostly obtained from wood. The process of creating paper from wood is very costly and requires many resources. For a resource-efficient production of wood pulp and paper, it is important that every single production process works efficiently. In addition to the efforts of the past much research has taken place in recent decades to discover further opportunities for sparing resources. These opportunities were found by consideration of the whole production process as one unit and allowing synergies. The single production processes are analyzed for identifying useful interconnections of material and energy flows between the processes. Such interconnections allow the partial reuse of outputs of certain processes as input for other processes. Thus, the cascade utilization of materials and energy within the production is possible. For example, the waste heat of a process can be used for heating up other material flows or the wastewater of a process can be used for other processes after recycling or after mixing with freshwater. This method is called process integration and is applied regularly in production planning for many chemical and procedural processes these days.
The pinch-analysis is one of the best known methods of process integration which is used for various objectives, mainly for heat recovery, fresh water minimization or recovery of organic solvents. Depending on the objective, the pinch-analysis includes an appropriate systematic procedure for showing possible resource savings. After this, the results are considered in the context of production planning.
The objective of the research work includes a first step of analyzing the material and energy flows within the paper- and wood pulp production by means of a pinch-analysis. For this, existing methods of the pinch-analysis are examined regarding their applicability and are possibly modified and developed further. Afterwards, various alternatives for resource savings are determined which are evaluated with reference to certain criteria. For this, different procedures of Multi-Criteria-Decision-Support are examined regarding their suitability.