Modeling energy consumption for the generation of microfibres from bleached kraft pulp fibres in a PFI mill

Abstract

The objective of this paper is to model the energy consumed in generating cellulose microfibres, 1 μm in diameter, as reinforcing agents, by refining bleached softwood kraft pulp in a PFI mill. An average initial fibre diameter of 13 μm was assumed. 125,000 revolutions in a PFI mill was found to produce a high yield of fibres 1.3 μm in diameter, and the minimum refining energy needed to reduce the fibre diameter to 1.3 μm was estimated as 1875 kJ for each 24 g charge in the PFI mill. Since elastic deformation of the fibres was found to be negligible, the size reduction was assumed to follow Rittinger’s Law. This gave a Rittinger’s constant of 28 J.m/kg for the given system. Using this value of Rittinger’s constant, the energy required to generate microfibres 1 μm in diameter was predicted as 2480 kJ for each 24 g charge in the PFI mill. It was deduced that microfibres generated in this way would cost a minimum of $2.37 per kilogram. Hence even this relatively inefficient method of grinding would not be prohibitively expensive, provided the resulting microfibres can be used as high quality reinforcements.

Improving Sugar Yields and Reducing Enzyme Loadings in the Deacetylation and Mechanical Refining (DMR) Process through Multistage Disk and Szego Refining and Corresponding Techno-Economic Analysis

“…PFI milling on predisk refined corn stover (disk refined at ∼128 kWh/ODMT) decreased the mean particle size to approximately 190 μm. Calculating the refining energy imparted by a PFI mill has many measurement difficulties, , and according to Kerekes, unbleached softwood pulp in a PFI mill can consume about 0.19–0.20 kWh/ton-rev. If we assume similar amounts of energy are needed, then the energy in PFI milling of our DRDCS substrate at 4000 rev is ∼760–800 kWh/ODMT, leading to a total refining energy consumption of approximately 890–930 kWh/ODMT including the energy from the disk refining step.…”

Production of Nanocellulose and Its Applications in Drug Delivery: A Critical Review

“…These result in internal and external fibrillation and, consequently, fiber size reduction. 139 Importantly, produced nanofibers through processes that include a PFI mill (or a Valley beater) contain a considerable amount of water. Consequently, it causes troubles during storage and handling because of the bulk volume and contamination concerns.…”

“…Also, rotating bars subject fibers to impact. These result in internal and external fibrillation and, consequently, fiber size reduction …”