'What Goes Around Comes Around' (A look at the Kraft Liquor Cycle using FT-NIR Technology)

摘要

"What goes around comes around" is a common phrase associated with cycles. The Kraft liquor cycle essentially deals with 1/2 of the log that comes into a mill along with the necessary chemicals used to transform the wood into pulp in the digester. It is an important cycle that in many cases can decide if a mill is profitable or not. Species changes in the digester and the manner in which the digester operates can greatly impact the black liquor that is sent to the recovery boiler. The manner in which the black liquor is handled at the recovery boiler can in turn determine the operations of the recausticizing and digester departments. The lignin content, the inorganic/organic content, and the REA (residual effective alkali) of weak black liquor can, and has, been tested for on a regular basis using an on line FT-NIR developed by Paprican (now FPInnovations) and Fitnir Analyzers Inc.(a licensee to FPInnovations). The first online determination of REA in black liquor using FT-NIR was commissioned in 1996. The first online inorganic /organic determinations that were performed with FT-NIR technology was implemented in 2007 and, using the same system, the first online lignin determination of weak black liquor data was achieved in 2008. This paper will show how changes in these important liquor parameters influences the nature of black liquor sent to the recovery boiler and the operational changes that can occur in the boiler as a result of a "changing" liquor.