Cross-linked glycerol polymer additives for pulping
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Solution Overview
Problem
The existing wood chip digestion processes in paper pulping, particularly in Kraft pulping, face challenges due to high pH levels causing surfactants to precipitate out of solution, reducing their effectiveness and leading to increased rejects and quality control issues.
Innovation Solution
Incorporating a cross-linked glycerol-based polymer additive with a branched structure into the cooking liquor, which enhances the penetration of pulping chemicals into wood chips, reducing lignin content and improving pulp quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If surfactants are added to white liquor to enhance penetration into wood chips, then digestion effectiveness is improved, but high pH causes surfactants to precipitate and lose effectiveness
Solution Approach 1:
The invention changes the chemical structure parameters of the surfactant by introducing a sulfonate group instead of traditional sulfate or carboxylate groups. This structural modification allows the surfactant to remain stable and soluble in high pH white liquor environments while maintaining its surface-active properties for enhancing penetration into wood chips.
Solution Approach 2:
The invention creates a composite surfactant molecule combining a hydrophobic alkyl chain for penetrating wood chips with a hydrophilic sulfonate head group that remains stable in alkaline conditions. This composite structure enables the surfactant to function effectively in the harsh white liquor environment without precipitating.
2Productivity
If surfactant concentration is increased to overcome precipitation, then penetration is improved, but cost increases and little additional improvement is achieved
Solution Approach 1:
By modifying the surfactant's chemical structure to include a sulfonate group, the invention achieves superior stability in high pH environments. This allows effective concentrations to be maintained without precipitation losses, reducing the total surfactant quantity needed compared to traditional surfactants that precipitate and require supersaturation to maintain effectiveness.
3Reliability
If temperature or pressure is reduced to maintain surfactant solubility, then surfactant stability is improved, but digestion efficiency decreases and rejects increase
Solution Approach 1:
The invention changes the chemical parameters of the surfactant by introducing a sulfonate group, which provides exceptional stability across a wide range of temperatures and pressures. This allows the surfactant to maintain solubility and effectiveness even at the high temperatures and pressures required for efficient wood chip digestion, eliminating the need to compromise digestion conditions.
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 cross-linked glycerol-based polymer additive significantly reduces lignin in the pulp, resulting in a lower kappa number and fewer rejects, while maintaining stability in high-temperature and alkaline environments, thus enhancing the pulping process efficiency.
Implementation Method 1
The surfactants reduce the surface tension at the interface between the white liquor and the wood chips
Implementation Method 2
This reduced surface tension allows the chemicals in the white liquor to penetrate more deeply into the wood chips
Data Source
AI summary
The invention provides a method of improving the digestion of wood chips into pulp. The method involves: adding a cross-linked glycerol-based polymer additive to a solution used in the digestion process. This additive is unexpectedly effective at facilitating digestion. The branched and ether structure of the additive allows it to withstand the harsh nature of a high stress environment. In addition, it is more soluble in the harsh condition than other surfactants. The structure, resistance, and particular balance between hydrophobic and hydrophilic regions, causes the additive to increases the interaction between the wood chips and the digestion chemicals. This in turn reduces the costs, the amount of additive needed, and the amount of reject wood chunks that result from the digestion process.