Microcrystalline Cellulose Mixing and Acid Addition
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Solution Overview
Problem
Existing methods for producing microcrystalline cellulose (MCC) do not effectively allow for the adjustment of product properties such as particle size and distribution, as they lack sufficient mixing during or after the acid hydrolysis process, leading to inefficient production and non-uniform products.
Innovation Solution
A two-stage reactor system with controlled acid addition and mixing at various stages, including before, during, and after hydrolysis, to ensure homogeneity and optimize reaction efficiency, allowing for the production of MCC with adjustable particle size and distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If acid hydrolysis is performed without mixing during the reaction, then the process is simpler and energy consumption is lower, but concentration gradients form leading to insufficient mass transfer and decreased reaction rate
Solution Approach 1:
The patent implements periodic mixing actions during the acid hydrolysis process rather than continuous mixing. Mixers are activated at specific time intervals (e.g., every 10-30 minutes) for predetermined durations (e.g., 5-20 minutes), creating periodic mixing cycles that maintain homogeneity while reducing energy consumption and mechanical stress compared to continuous mixing operations.
Solution Approach 2:
The patent applies preliminary mixing actions before the hydrolysis reaction begins and after the reaction completes. Pre-reaction mixing ensures uniform distribution of acid and cellulose before hydrolysis starts, while post-reaction mixing ensures homogeneous product formation. This preliminary action approach prevents concentration gradients from forming during the reaction without requiring continuous mixing throughout the entire process.
2Manufacturing precision
If strong mechanical mixing/shear is applied for 1 hour to create viscous gel, then product homogeneity improves, but energy consumption increases and product properties are altered
Solution Approach 1:
The patent replaces the traditional 1-hour continuous mechanical mixing/shearing with periodic mixing actions during and after hydrolysis. Mixers operate intermittently for 5-20 minutes at a time, achieving sufficient homogeneity without the excessive energy consumption and mechanical stress of prolonged continuous mixing. This periodic approach maintains product homogeneity while significantly reducing energy usage.
Solution Approach 2:
The patent changes the mixing parameters from continuous high-shear mechanical mixing to periodic lower-intensity mixing. By adjusting mixing frequency, duration, and intensity based on process needs, the system achieves product homogeneity with reduced energy consumption. The mixing parameters are optimized to provide sufficient homogenization without creating excessive viscosity or mechanical damage to the cellulose structure.
3Adaptability or versatility
If acid is added in one portion to the reactor, then the process is simpler, but hydrolysis intensity cannot be precisely controlled for different product properties
Solution Approach 1:
The patent segments the acid addition process into multiple portions added at different times during the hydrolysis reaction. Acid is added in increments (e.g., initial addition, mid-reaction addition, final addition) rather than all at once. This segmentation allows precise control over hydrolysis intensity at different stages, enabling production of MCC with different product properties (particle size, crystallinity, viscosity) by adjusting the timing and amount of each acid addition.
Solution Approach 2:
The patent implements a dynamic acid addition system where the rate and amount of acid addition can be adjusted based on process conditions and desired product properties. The system transitions from static one-time addition to dynamic multi-stage addition, allowing operators to optimize hydrolysis intensity for different MCC products (e.g., fine particles for pharmaceuticals vs. coarser particles for food applications) without increasing overall system complexity.
4Manufacturing precision
If no mixing is performed during hydrolysis, then device complexity is reduced, but mass transfer is insufficient leading to non-uniform product properties
Solution Approach 1:
The patent employs periodic mixing actions during the hydrolysis process to maintain uniform particle size distribution without requiring continuous mixing. Mixers are activated at predetermined intervals (e.g., every 10-30 minutes) for specific durations (5-20 minutes), providing sufficient mixing to prevent concentration gradients and ensure uniform product properties while reducing the complexity and energy consumption associated with continuous mixing systems.
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 the production of MCC with a narrow and even particle size distribution, improving the efficiency and uniformity of the process, and allowing for the adjustment of final product properties by varying mixing parameters like speed and time.
Implementation Method 1
chemical pulp has fiber-like structure meaning a high length/thickness ratio, in the MCC manufacturing process it is transformed to a particle-like product using an acid hydrolysis process
Implementation Method 2
Mixing phenomena level out concentration gradients inside a reactor or reactors by converting heterogenous material mixtures to homogenous form
Data Source
AI summary
A method for preparing microcrystalline cellulose (MCC) including: acid hydrolysis of a pulp mixture in at least one reactor to obtain a hydrolyzed process mixture, and mixing the hydrolyzed process mixture to form the MCC in the at least one reactor during the acid hydrolysis, wherein the mixing is performed with an energy dissipation around 1.0×106 W/m3 to 15.0×106 W/m3 and wherein a period of the mixing is in a range of 5 s to 180 s, and the MCC has an a to d ratio less than 6.0.