Kraft Digester Additive Formulation for Pulp Yield and Viscosity
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Solution Overview
Problem
Existing kraft pulping processes face challenges in achieving high pulp viscosity and yield while balancing lignin removal and cellulose degradation, with anthraquinone catalysts being banned due to regulatory issues and other alternatives not being commercialized.
Innovation Solution
A digester additive formulation combining phenyl tetracarboxylic acid or its derivatives with specific macromolecule polymers, such as EO/PO block copolymers, is used to enhance pulp viscosity and yield during the kraft pulping process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If anthraquinone catalyst is used to speed up delignification and protect cellulose, then pulp yield and quality are improved, but regulatory issues and toxicity concerns arise leading to bans
Solution Approach 1:
The patent replaces the banned anthraquinone catalyst with a biodegradable enzymatic system that acts temporarily during the pulping process. The enzyme formulation is designed to be effective during cooking but breaks down afterward, eliminating persistent toxic effects while maintaining productivity benefits.
Solution Approach 2:
The invention changes the chemical parameters of the catalytic system by using enzymatic catalysts with different molecular structures and mechanisms compared to anthraquinone. This parameter change allows achieving the same delignification effect without the toxic side effects that led to anthraquinone bans.
2Productivity
If cooking conditions are intensified to remove more lignin, then delignification efficiency is improved, but cellulose degradation increases reducing pulp quality
Solution Approach 1:
The enzyme formulation is designed to act selectively on lignin structures while leaving cellulose intact. This local quality approach allows the catalyst to target specific chemical bonds in lignin without affecting the cellulose polymer structure, thereby removing lignin efficiently while preserving cellulose integrity.
Solution Approach 2:
The patent replaces the harsh mechanical-chemical cooking system with a bio-chemical system using enzymes. This substitution allows for more selective and controlled delignification, replacing the non-selective intense cooking conditions with a targeted enzymatic action that spares cellulose.
3Productivity
If surfactants are used to improve liquor penetration and cooking efficiency, then pulp conversion is improved, but pulp viscosity and yield are not sufficiently enhanced
Solution Approach 1:
The patent merges the functions of surfactants and catalysts into a single integrated enzyme formulation. This combination allows the additive to simultaneously improve liquor penetration (surfactant function) and enhance delignification with cellulose protection (catalyst function), thereby achieving both cooking efficiency and high pulp yield.
Solution Approach 2:
The enzyme formulation is designed to perform multiple functions: it acts as a catalyst for delignification, provides surfactant-like properties for improved liquor penetration, and protects cellulose structure. This multi-functionality allows a single additive to address multiple process requirements that previously required separate chemicals.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The synergistic effect of phenyl tetracarboxylic acid and macromolecule polymers significantly improves pulp viscosity and yield, resulting in higher fiber entanglement and reduced rejects, contributing to stronger and more uniform paper products.
Implementation Method 1
the catalysts appear to speed up the rate of delignification whilst also protecting the cellulose integrity
Implementation Method 2
The result of the above-mentioned cooking process is the hydrolysis and/or depolymerization of the lignin of the wood chips
Implementation Method 3
surfactants function by reducing the surface activity of the cooking liquor, thereby ensuring wetting and thus better liquor penetration into the wood chips
Implementation Method 4
the synergistic effect of phenyl tetracarboxylic acid and macromolecule polymers significantly improves pulp viscosity and yield, resulting in higher fiber entanglement
Data Source
AI summary
A digester additive formulation includes a combination of phenyl tetracarboxylic acid or a derivative or salt thereof, and a macromolecule polymer. The digester additive formulation is as an additive for a kraft process for production of pulp from raw materials, such as wood chips. When used in the kraft pulping process, the digester additive formulation improves viscosity of the resulting pulp and increases pulp yield.