CTMP process optimization Part I: Internal and external variables impact on refiner conditions
Anders Karlström and Jan Hill
In this paper, internal variables (e.g. temperature, consistency and fiber residence time) are introduced and defined as physical states obtained in different parts of the refining zones. In short, they differ from the traditional external variables (e.g. dilution water feed rate and specific energy), which are not available as distributed variables from refining zone measurements.
The internal variables can be seen as the backbone of physical models and we illustrate that based on a model for a CD-82 refiner in a CTMP production line. Such a model can be used for on-line implementation of soft sensors for advanced process control and it is shown that the refining segment pattern affects the temperature profile. It is particularly interesting to study how the segment parameters in terms of the distributed width of the bars and grooves together with the segment taper affect the back-flowing steam, the cross-sectional area and thereby the fiber residence time.
To illustrate the capability to use a modeling strategy it is shown how to reach a 40% reduction in specific energy without violating the required pulp properties.
CTMP, Energy efficiency, Fiber residence time, Fiber-to-bar interaction, Modeling, Motor load distribution, Pulp consistency, Temperature profile
Nordic Pulp & Paper Research Journal (NPPRJ) is an international scientific magazine covering science and technology for the areas of wood or bio-mass constituents, pulp and paper and including new fiber-based materials, recovery and by-products from pulping processes, bio-refining and energy issues. Articles meeting required scientific standards are accepted from any continent. Open Access: Articles not available through Gold Open Access may be purchased by credit card as a pdf file, to be downloaded within 24 h after ordering, at a price of 22 EUR per article. (Value added tax may apply depending on your location, which you enter at payment logout.) Such articles have Green Open Access, i.e. authors may share articles on their personal non-commerical homepage immediately after publication on the website and download them to non-commercial hosting platforms one year after publication in a full issue of NPPRJ. ISSN: 0283-2631