In English

Energy study of tissue machines

Charlotte Lundin
Göteborg : Chalmers tekniska högskola, 2011. 88 s.
[Examensarbete på avancerad nivå]

In a world where global warming and environmental issues are becoming more relevant questions regarding the use of energy are becoming more important. Metso Paper Karlstad and Metsä Tissue are among many companies striving towards increasing the energy efficiency of their tissue paper machines. This was the objective of this Master’s Thesis; to perform an energy study with the tool named pinch analysis to investigate potential energy efficiency improvements of tissue paper machines. Pinch analysis indentifies potential reduction in external hot and cold utilities and also the potential in increased energy efficiency through process integration. The study was performed on an existing mill; Katrinefors mill, a computer simulated machine including only the Yankee hood and also the same computer simulated Yankee hood in a scaled model of the Katrinefors mill. A separate pinch analysis was performed on the three machines. The results showed potential reduction in utilities for all three machines; 17% for the Katrinefors mill, 21,5% for the computer simulated Yankee hood and 21% for the computer simulated Yankee hood in a scaled model of the Katrinefors mill. In this work retrofits are also proposed which presents alternatives on how to reduce the utility demand. Other indications, not originating directly from the pinch analysis were also taken into consideration in the retrofit that can contribute to a reduced utility demand. These were mainly potential process integration possibilities which implied integrations that would increase the energy efficiency of the machine. Two possibilities were visible and the most important one, which was present for all three machines, implied that parts of the steam used inside the Yankee cylinder could be generated with the moist air extracted from the Yankee hood. Further cooling and condensing the moist air contributed to the increased energy efficiency since the heat available was utilised to a greater extent. For the suggested retrofits the amount of energy saved for the Katrinefors mill is 182 kWh per tonne tissue paper, 270 for the Yankee hood and the same number for the computer simulated Yankee hood in a scaled model of the Katrinefors mill. There are two main benefits for the suggested retrofit; first and foremost the system would become more energy efficient since the energy available would be utilized more effectively through further condensation and cooling of the moist air. Secondly the demand for hot utilities would be decreased as part of the steam could potentially be generated by the moist air stream.

Nyckelord: Paper machine model, Katrinefors mill, Pinch analysis, Energy efficiency



Publikationen registrerades 2011-11-23. Den ändrades senast 2013-04-04

CPL ID: 148877

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