Evaluation of fines separation from unbleached softwood kraft pulp using microperforated hole screens

Abstract The application of a bench scale and an industrial scale pressure screen to separate cellulosic fines from an unbleached softwood kraft pulp containing 5 % (w/w) primary fines was investigated and the results were compared. In the bench scale trials different microperforated screens with hole diameters of 150 µm, 250 µm, 400 µm and 600 µm were used. Based on these results a screen hole diameter of 400 µm was selected for the industrial scale trials. In all cases, a high accept flow rate proved to be the crucial parameter for high removal efficiency of the fines material and a removal efficiency of well above 50 % could be achieved. Further of interest were the limiting factors regarding increased accept flow rates with a focus on the interrelations between pressure difference, slot velocity and reject consistency. As expected, investigation of electric energy demand showed a correlation between removal efficiency and specific energy consumption, which did not exceed 35 kWh/t(od) feed.

Download Full-text

Simultaneous bench scale production of dissolving grade pulp and valuable hemicelluloses from softwood kraft pulp by ionic liquid extraction

Carbohydrate Polymers ◽

10.1016/j.carbpol.2015.09.039 ◽

2016 ◽

Vol 136 ◽

pp. 402-408 ◽

Cited By ~ 13

Author(s):

Christiane Laine ◽

Sari Asikainen ◽

Riku Talja ◽

Agnes Stépán ◽

Herbert Sixta ◽

...

Keyword(s):

Ionic Liquid ◽

Kraft Pulp ◽

Liquid Extraction ◽

Scale Production ◽

Bench Scale ◽

Softwood Kraft Pulp

Download Full-text

Application of pure, thermostable, alkali-tolerant xylanase in bleaching of oxygen-delignified pine kraft pulp

TAPPI Journal ◽

10.32964/tj14.11.689 ◽

2015 ◽

Vol 14 (11) ◽

pp. 689-694

Author(s):

QINGZHI MA ◽

QI WANG ◽

CHU WANG ◽

NIANJIE FENG ◽

HUAMIN ZHAI

Keyword(s):

Intrinsic Viscosity ◽

Chlorine Dioxide ◽

High Purity ◽

Kraft Pulp ◽

Alkaline Media ◽

Industrial Scale ◽

Elemental Chlorine ◽

Effect Of Oxygen ◽

Alkaline Tolerant ◽

Ecf Bleaching

The effect of oxygen (O2)-delignified pine kraft pulp pretreatment by high-purity, thermostable, and alkaline-tolerant xylanases on elemental chlorine free (ECF) bleaching of O2-delignification kraft pulp was studied. The study found that xylanase pretreatment preserved the intrinsic viscosity and yield of O2-delignified pulp while causing about 7% of delignification with high delignification selectivity. The xylanases with high purity, higher thermostability (75°C~80°C) in highly alkaline media (pH 8.0~9.5) could be applied on an industrial scale. Pulp pretreatment by the high-purity, thermostable, and alkaline tolerant xylanases could improve pulp brightness or reduce the chlorine dioxide (ClO2) consumption. In a D0ED1D2 bleaching sequence using the same amount of ClO2, the xylanase-pretreated pulp obtained a higher brightness (88.2% vs. 89.7% ISO) at the enzyme dose of 2 U/g pulp; or for the same brightness as control (88.2% ISO), the ClO2 dosage in the D0 stage was reduced by 27%, which represents a 16% savings in total ClO2 used for bleaching.

Download Full-text

Optimization of elemental chlorine-free bleaching for a softwood kraft pulp • part 2: economic analysis of chemical and steam consumption

TAPPI Journal ◽

10.32964/tj9.9.47 ◽

2010 ◽

Vol 9 (9) ◽

pp. 47-53 ◽

Cited By ~ 2

Author(s):

BRIAN N. BROGDON

Keyword(s):

Chlorine Dioxide ◽

Previous Investigation ◽

Kraft Pulp ◽

Energy Costs ◽

Alkaline Extraction ◽

Stage Versus ◽

Kraft Pulps ◽

Steam Consumption ◽

Elemental Chlorine ◽

Softwood Kraft Pulp

Our previous investigation [1] re-analyzed the data from Basta and co-workers (1992 TAPPI Pulping Conference) to demonstrate how oxidative alkaline extraction can be augmented and how these changes affect chlorine dioxide consumption with elemental chlorine-free (ECF) sequences. The current study manipulates extraction delignification variables to curtail bleaching costs with a conventional U.S. Southern softwood kraft pulp. The economic advantages of ~0.35% to 0.65% H2O2 peroxide reinforcement in a 70°C (EOP)-stage versus 90°C (EO)-stage are predisposed to the brightness targets, to short or long bleach sequences, and to mill energy costs. Minimized bleaching costs are generally realized when a 90°C (EO) is employed in D0(EO)D1 bleaching, whereas a 70°C (EOP) is economically advantageous for D0(EOP)D1E2D2 bleaching. The findings we disclose here help to clarify previous ECF optimization studies of conventional softwood kraft pulps.

Download Full-text

An effective method for determining the retention and distribution of cellulose nanofibrils in paper handsheets by dye labeling

TAPPI Journal ◽

10.32964/tj17.03.157 ◽

2018 ◽

Vol 17 (03) ◽

pp. 157-164 ◽

Cited By ~ 3

Author(s):

Shengdan Wang ◽

Wenhua Gao ◽

Kefu Chen ◽

Jinsong Zeng ◽

Jun Xu ◽

...

Keyword(s):

Correlation Coefficient ◽

Congo Red ◽

Kraft Pulp ◽

Cellulose Nanofibrils ◽

Standard Curve ◽

Congo Red Dye ◽

Mechanical Disintegration ◽

Softwood Kraft Pulp ◽

White Water ◽

Red Dye

Cellulose nanofibrils (CNF) were prepared by cellulase in conjunction with mechanical disintegration from the bleached softwood kraft pulp and labelled by Congo red dye. The labelled CNF were used to investigate the retention and distribution of CNF in paper handsheets. The retention of the labelled CNF was obtained by measuring the absorbance of white water using an ultraviolet-visible spectrophotometer. The results showed that this method for measuring the retention was rapid, feasible, and sensitive, owing to the high correlation coefficient R2 (0.9993) of the standard curve. The labelled CNF showed even distribution in paper handsheets. The colorimetric values of paper handsheets were explored with a residual ink analyzer.

Download Full-text