In English

Tillämpning av energieffektiv svartlutsindunstning

Anna Wilhelmsson
Göteborg : Chalmers tekniska högskola, 2002.
[Examensarbete på avancerad nivå]

A pulp and paper mill has a large energy demand and the evaporation plant is one of the most energy demanding plants in a mill. In the event of a major rebuilding of the chemical recovery cycle there are several possibilities to make it more energy efficient and this ought to be considered when rebuilding the plant. Process integration of the evaporation plant decreases the operating cost or makes it possible to evaporate more liquor and/or purify more condensate. In this work the possibilities to integrate the evaporation plant including strippers has been studied. The study is a part of a PhD-project at the Department of Heat and Power Technology at Chalmers University of Technology. The PhD-project is an investigation of the energy saving potential at Skoghall mill, Sweden. Several different designs of the plant have been analysed in a simulation model in Excel that was developed at the Department of Heat and Power Technology. The existing model has been modified for different evaporation plants combined with strippers. An economic analysis where both operating cost and investment cost have been considered is also included. The possibilities to purify effluent from the CTMP-process (Chemi Thermo Mechanical Pulp) and to recover purified condensates are also investigated. An extra effect and an integrated stripper lower the energy demand of the plant by 13 % compared to a nonintegrated plant. The investment has also been shown to be profitable with the economic conditions set in this study. Purification of the CTMP-effluent by evaporating the effluent together with the black liquor is a profitable solution. The operating cost is approximately equal to when only black liquor is evaporated but the investment cost is slightly higher. Recovery of purified condensates is advisable due to unchanged operating cost.



Publikationen registrerades 2007-12-21. Den ändrades senast 2013-04-04

CPL ID: 63791

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