A novel rotation generator of hydrodynamic cavitation for the fibrillation of long conifer fibers in paper production.

Janez Kosel,Matevž Dular,Andrej Šinkovec

doi:10.1016/j.ultsonch.2019.104721

Abstract

Refining of cellulose pulp is a critical step in obtaining high quality paper characteristics, however, this process is slow and costly especially for refining longer conifer fibers which are the preferred source for high quality paper production and give the paper its strength. In this study, we have applied a novel rotation generator of hydrodynamic cavitation for refining conifer rich pulp samples. Our results show that the device is capable of generating intense shear forces and multiple zones of developed cavitation and is successful in increasing the drainage rate of high consistency pulp (3%). The paper produced by means of the obtained pulp has higher quality because of its higher tensile index (50.5 kN m kg-1) and burst index (3 kPa m2 g-1). These physical parameters were sufficient for newsprint paper and other paper/board quality manufacture. In addition, this laboratory scale rotation generator proved to be economically efficient in comparison to the routinely employed laboratory beaters. To our knowledge, this is the first example of using hydrodynamic cavitation for the refinement of softwood fiber pulp of standard industrial consistencies (3%).

Highlights

Because of market competition and high energy costs associated with pulp processing, paper industry is continuously searching for environmentally friendly strategies
At a rotation frequency of 1000 rpm and at flow rate of 7.5 L/min (PL of 153 kPa; head of rotation generator of hydrodynamic cavitation (RGHC) device was 7.0 m) the σ value was 43.6, which is high enough to ensure that the RGHC was operating in noncavitating conditions
10 m) the σ value was 0.7 which indicates an even greater cavitation intensity. This was reflected in the higher shear rates which were generated inside the treatment chamber

Summary

Introduction

Because of market competition and high energy costs associated with pulp processing, paper industry is continuously searching for environmentally friendly strategies. The main efforts of paper industry are focussed in how to produce high quality pulp from commonly found plant material in a production process that consumes low amounts of water and energy [1]. To raw material selection, refining (beating) has the greatest influence on the final paper quality by improving fiber flexibility, smoothness and bonding ability [2]. Refining causes breakage of hydrogen bonds among the microfibrils, which subsequently increases the surface of microfibrils and the ability of fibers to establish links between them and the fibrillation of fibers [7,8]

Methods

Results

Discussion

Conclusion