Woodchip impregnation with weak white liquor and its effect in mitigating operational costs and environmental impacts in Kraft pulp mills

2021 ◽  
Author(s):  
Jonas K. Johakimu ◽  
Bruce B. Sithole
Keyword(s):  
Environmental Impacts ◽  
Kraft Pulp ◽  
Pulp Mills ◽  
White Liquor ◽  
Operational Costs ◽  
Kraft Pulp Mills

Cleavage of acetyl groups from northeast hardwood for acetic acid production in kraft pulp mills

TAPPI Journal ◽  
2013 ◽  
pp. 57-67 ◽  
Author(s):  
RAVIKANT PATIL ◽  
JOSEPH M. GENCO ◽  
HEMAND PENDSE ◽  
ADRIAAN VAN HEININGEN
Keyword(s):  
Acetic Acid ◽  
Kraft Pulp ◽  
Ion Concentration ◽  
Alkali Concentration ◽  
Extraction Temperature ◽  
Pulp Mills ◽  
Hydroxide Ion ◽  
Green Liquor ◽  
White Liquor ◽  
Kraft Pulp Mills

This study identified the optimum conditions for cleavage of acetyl groups from wood hemicelluloses for possible conversion to salts of acetate or to acetic acid in kraft pulp mills. Acetyl groups in wood hemicelluloses can be hydrolyzed by either OH- (hydroxide) or H+ (hydronium) ions. Experimental data are presented for the extraction of industrial northeast hardwood chips using alkali streams that are available in the kraft pulp mills: caustic, green liquor, and white liquor. The effects of extraction time, chip soaking temperature, alkali concentration, and extraction temperature on cleavage of acetyl groups were investigated. Soaking at elevated temperature was found to be more effective than no soaking or soaking at room temperature. The rate of cleavage of acetyl groups from wood hemicelluloses was proportional to the initial hydroxide ion concentration in the liquor. Both white liquor and 0.5 N sodium hydroxide had higher rates of hydrolysis of acetyl groups compared to green liquor, which contained fewer hydroxide ions. The initial hydroxide ion concentration in the liquor also determined the mechanism by which acetyl groups were hydrolyzed from the hemicellulose backbone. If the extraction liquor contained excess hydroxide ions, then most acetyl groups were directly hydrolyzed from the xylan polymer to form sodium acetate, and the xylan remained in the wood, provided the temperature was low. The extraction temperature had a negligible effect on rate of cleavage of acetyl groups if the liquor contained excess hydroxide ions.

Effects of added materials on black liquor combustion

TAPPI Journal ◽  
2016 ◽  
Vol 15 (7) ◽  
pp. 479-486
Author(s):  
LIMING ZHAO ◽  
DANIELLY CORTES ◽  
HONGHI TRAN
Keyword(s):  
Systematic Study ◽  
Sodium Sulfate ◽  
Kraft Pulp ◽  
Black Liquor ◽  
The Other ◽  
Pulp Mills ◽  
Combustion Behavior ◽  
White Liquor ◽  
Other Hand ◽  
Kraft Pulp Mills

Black liquor is often mixed with various types of materials before being burned in a recovery boiler to meet specific needs of kraft pulp mills. A systematic study was conducted using a thermogravimetric combustor to examine how added materials might affect the combustion behavior of black liquors obtained from several pulp mills. The results show that adding soap, caustic, white liquor, and sawdust significantly reduces the liquor swelling tendency, thereby requiring a longer time for the liquor to burn completely. Adding makeup saltcake, precipitator ash, sodium sulfate, and biosludge, on the other hand, has little or no effect on the liquor combustion behavior.

The solubility of calcium carbonate  in green liquor handling systems

TAPPI Journal ◽  
2019 ◽  
Vol 18 (10) ◽  
pp. 595-602
Author(s):  
ALISHA GIGLIO ◽  
VLADIMIROS G. PAPANGELAKIS ◽  
HONGHI TRAN
Keyword(s):  
Calcium Carbonate ◽  
Systematic Study ◽  
Kraft Pulp ◽  
Thermodynamic Simulation ◽  
Solubility Data ◽  
Pulp Mills ◽  
Persistent Problem ◽  
Green Liquor ◽  
Kraft Pulp Mills ◽  
Salt Systems

The formation of hard calcite (CaCO3) scale in green liquor handling systems is a persistent problem in many kraft pulp mills. CaCO3 precipitates when its concentration in the green liquor exceeds its solubility. While the solubility of CaCO3 in water is well known, it is not so in the highly alkaline green liquor environment. A systematic study was conducted to determine the solubility of CaCO3 in green liquor as a function of temperature, total titratable alkali (TTA), causticity, and sulfidity. The results show that the solubility increases with increased temperature, increased TTA, decreased causticity, and decreased sulfidity. The new solubility data was incorporated into OLI (a thermodynamic simulation program for aqueous salt systems) to generate a series of CaCO3 solubility curves for various green liquor conditions. The results help explain how calcite scale forms in green liquor handling systems.

Toward Production of Bioethanol Using Pulp Rejects from Kraft Pulp Mills as Raw Materials

2013 ◽  
Vol 67 (11) ◽  
pp. 1248-1251
Author(s):  
Masanori Kishino ◽  
Ken Orihashi ◽  
Akira Harada
Keyword(s):  
Kraft Pulp ◽  
Raw Materials ◽  
Pulp Mills ◽  
Kraft Pulp Mills

SOLID WASTE GENERATION IN KRAFT PULP MILLS

2004 ◽  
Vol 3 (3) ◽  
pp. 399-404 ◽  
Author(s):  
Dan Gavrilescu
Keyword(s):  
Solid Waste ◽  
Kraft Pulp ◽  
Waste Generation ◽  
Pulp Mills ◽  
Kraft Pulp Mills ◽  
Solid Waste Generation

Activated Sludge Treatment of Kraft Mill Effluents from Conventional and Oxygen Bleaching

1991 ◽  
Vol 24 (3-4) ◽  
pp. 427-430 ◽  
Author(s):  
J. Nevalainen ◽  
P.-R. Rantala ◽  
J. Junna ◽  
R. Lammi
Keyword(s):  
Activated Sludge ◽  
Kraft Pulp ◽  
Activated Sludge Process ◽  
Chlorinated Phenols ◽  
Pulp Mills ◽  
Main Interest ◽  
Sludge Treatment ◽  
Kraft Pulp Mills ◽  
Activated Sludge Processes ◽  
Oxygen Bleaching

Conventional and oxygen bleaching effluents from hardwood kraft pulp mills were treated in laboratory-scale activated sludge processes. The main interest was the fate of organochlorine compounds in the activated sludge process. In the treatment of conventional bleaching wastewaters the BOD7-reduction was 80-91 % and in oxygen bleaching wastewaters 86-93 %. The respective CODCr removals were about 40 % and about 50 %. The AOX reductions were on average 22 % and 40 % in the treatment of conventional and oxygen bleaching effluents, respectively. The reductions of chlorinated phenols, guajacols and catecols were usually more than 50 % in both reactors. Very little accumulation of AOX into the sludge was observed. The stripping of AOX from aeration unit was insignificant.

scholarly journals Decarbonization of industry: Implementation of energy performance indicators for successful energy management practices in kraft pulp mills

2021 ◽  
Vol 7 ◽  
pp. 1808-1817
Author(s):  
Elias Andersson ◽  
Henric Dernegård ◽  
Magnus Wallén ◽  
Patrik Thollander
Keyword(s):  
Energy Management ◽  
Performance Indicators ◽  
Kraft Pulp ◽  
Management Practices ◽  
Energy Performance ◽  
Pulp Mills ◽  
Kraft Pulp Mills

State of the art methods for combined water and energy systems optimisation in Kraft pulp mills

2021 ◽  
Author(s):  
Elvis Ahmetović ◽  
Zdravko Kravanja ◽  
Nidret Ibrić ◽  
Ignacio E. Grossmann ◽  
Luciana E. Savulescu
Keyword(s):  
Kraft Pulp ◽  
State Of The Art ◽  
Energy Systems ◽  
Pulp Mills ◽  
Art Methods ◽  
Kraft Pulp Mills

Fate of phosphorus in the recovery cycle of the kraft pulping process

TAPPI Journal ◽  
2020 ◽  
Vol 19 (3) ◽  
pp. 139-148
Author(s):  
MARYAM SADEGH MOUSAVI ◽  
NIKOLAI DEMARTINI
Keyword(s):  
Kraft Pulp ◽  
Pulp Mill ◽  
Field Studies ◽  
Kraft Pulping ◽  
Pulp Mills ◽  
Recovery Cycle ◽  
Green Liquor ◽  
Green Liquor Dregs ◽  
Kraft Pulp Mills ◽  
Negative Effect

The accumulation of nonprocess elements in the recovery cycle is a common problem for kraft pulp mills trying to reduce their water closure or to utilize biofuels in their lime kiln. Nonprocess elements such as magne-sium (Mg), manganese (Mn), silicon (Si), aluminum (Al), and phosphorus (P) enter the recovery cycle via wood, make-up chemicals, lime rock, biofuels, and process water. The main purge point for these elements is green liquor dregs and lime mud. If not purged, these elements can cause operational problems for the mill. Phosphorus reacts with calcium oxide (CaO) in the lime during slaking; as a result, part of the lime is unavailable for slaking reactions. The first part of this project, through laboratory work, identified rhenanite (NaCa(PO4)) as the form of P in the lime cycle and showed the negative effect of P on the availability of the lime. The second part of this project involved field studies and performing a mass balance for P at a Canadian kraft pulp mill.

Excess heat from kraft pulp mills: Trade-offs between internal and external use in the case of Sweden—Part 1: Methodology

Energy Policy ◽  
2008 ◽  
Vol 36 (11) ◽  
pp. 4178-4185 ◽  
Author(s):  
Inger-Lise Svensson ◽  
Johanna Jönsson ◽  
Thore Berntsson ◽  
Bahram Moshfegh
Keyword(s):  
Kraft Pulp ◽  
Pulp Mills ◽  
Excess Heat ◽  
Trade Offs ◽  
Kraft Pulp Mills
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