Microcellulose Production via High-Consistency Acid Hydrolysis
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Solution Overview
Problem
Existing microcellulose manufacturing processes are inefficient and economically unviable due to high chemical usage and energy consumption, particularly in kraft pulp mills, which face challenges in balancing sodium-sulfur ratios and managing sulfur removal.
Innovation Solution
A process integrating acid hydrolysis of fibrous cellulosic material at high consistency and elevated temperature, utilizing the pulp mill's chemical recovery system to produce microcellulose, with optional acidification and washing steps to control particle size distribution, reducing the need for external acids and energy input.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If acid hydrolysis is performed with high acid dosage and low consistency, then microcellulose can be produced, but chemical consumption increases and heating demand increases
Solution Approach 1:
The invention changes the consistency parameter from low (5% in prior art) to high (15-50%), and adjusts acid dosage accordingly (0.5-5% vs 1-10%). This parameter change reduces both heating demand and acid consumption while maintaining microcellulose production efficiency
Solution Approach 2:
The process integrates with pulp mill chemical recovery systems to produce and reuse acids and chemicals in-situ, reducing external chemical inputs. The high consistency process generates concentrated hydrolysate that can be directly utilized in pulp mill operations
2Manufacturing precision
If mechanical disintegration is applied after acid hydrolysis, then particle size is reduced to micron range, but energy consumption increases significantly
Solution Approach 1:
The invention replaces mechanical disintegration systems (refiners requiring 5-100 kWh/ton) with a chemical process approach. Acid hydrolysis at high consistency directly produces microcellulose with controlled particle sizes through chemical breakdown rather than mechanical shearing
Solution Approach 2:
By changing the consistency parameter to high levels (15-50%) and adjusting acid dosage and temperature, the process achieves particle size reduction through chemical hydrolysis kinetics rather than mechanical force, eliminating the need for energy-intensive refining equipment
3Ease of manufacture
If extruder is used for acid hydrolysis, then intimate contact between cellulose and acid is achieved, but equipment cost and maintenance cost increase
Solution Approach 1:
The invention extracts the essential function of intimate contact from complex extruder equipment. High consistency mixing in simple reactors achieves sufficient contact between cellulose and acid without requiring expensive extrusion machinery with compression ratios of 1.5:1 to 3:1
Solution Approach 2:
The process uses simple, inexpensive reaction vessels instead of costly extruders. The high consistency approach allows effective hydrolysis in basic reactors that are cheaper to purchase, operate, and maintain, sacrificing neither contact efficiency nor hydrolysis effectiveness
4Use of energy by stationary object
If acid hydrolysis is performed at low consistency, then heating demand increases, but process simplicity is maintained
Solution Approach 1:
The invention changes the consistency parameter from low (5%) to high (15-50%), which directly reduces heating demand. The concentrated system requires less energy to heat and process, while the integrated chemical recovery system manages the increased complexity of chemical balancing
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
This approach enables efficient production of microcellulose with controlled particle sizes and high purity, while improving the sodium-sulfur balance in kraft pulp mills, reducing chemical and energy costs, and enhancing the overall economic viability of microcellulose production.
Implementation Method 1
hydrolyzing fibrous cellulosic material with an acid at an elevated temperature of at least 80°C
Data Source
Figure 1
Figure 2
Figure 3~5
AI summary
The present invention relates to a process for producing microcellulose comprising hydrolyzing fibrous cellulosic material with an acid at an elevated temperature or acidifying fibrous cellulosic material followed by washing and hydrolyzing the washed cellulosic material at an elevated temperature to produce a microcellulose - hydrolysate mixture followed by separation of the microcellulose from the hydrolysate, wherein the mixture or separated hydrolysate or microcellulose is optionally neutralized, and wherein the microcellulose production is integrated to production of a pulp mill such that at least part of chemicals used in the acidification, acid hydrolysis and/or neutralization is produced by an integrated chemical recovery process of the pulp mill.