A Review of Gas Flows in Fiber Suspensions, 2003 Spring Technical Conference Proceedings

Gas flows in fiber suspensions are found in all aspects of the pulp and paper industry, from paper recycling to pulping and bleaching to papermaking. Sometimes gas is added intentionally for a specific purpose, like in flotation deinking or bleaching with gaseous chemicals, or gas is entrained unintentionally with undesirable results, like in washing and paper forming. Various gas flow characteristics are important to quantify gas flow in fiber suspensions; these include the local and average volumetric gas fraction (termed gas holdup or void fraction), gas flow regime and bubble size.

Gas in fiber suspensions, introduced either intentionally or unintentionally, can cause several problems in pulp and paper processing, from reduced equipment capacity to poor paper machine performance. Various researchers have attempted to quantify selected gas flow characteristics in fiber suspensions and their relationship to pulp and paper mill performance. Some success has been achieved, but much more must be done to describe the complete picture.