Continuous Flow Extraction Reactor for Cellulosic Solvent Recovery
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Solution Overview
Problem
Current solvent recovery processes for regenerated cellulosic molded bodies, such as lyocell fibers, are inefficient and water-intensive, requiring multiple leaching cycles and large amounts of water, leading to increased environmental impact and high chemical oxygen demand in wastewater treatment.
Innovation Solution
A continuous flow extraction process using a liquid extraction medium in a reactor with a top-to-bottom flow configuration, maximizing solvent concentration gradients for efficient solvent extraction from cellulosic particles, reducing water consumption and extraction time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If batch-type leaching process with multiple cycles is used to recover solvent from cellulosic particles, then low residual solvent concentrations can be achieved, but the process becomes very slow and requires large amounts of water
Solution Approach 1:
The patent applies continuous flow extraction where the extraction medium continuously flows through the cellulosic particles in a column, replacing the batch-type cyclic leaching process. This continuous action maintains constant concentration gradients and enables simultaneous extraction across all particle contacts, dramatically reducing both water consumption and extraction time while achieving low residual solvent concentrations
2Quantity of substance
If batch-type soaking process is used for solvent extraction, then solvent can be recovered from production wastes, but the extraction efficiency is low due to equilibration effects and slow diffusion
Solution Approach 1:
The patent transforms the static batch soaking process into a dynamic continuous flow system where the extraction medium constantly moves through the particle bed. This dynamic flow prevents equilibration between the extraction medium and particles, maintaining driving concentration gradients throughout the process and enabling rapid, efficient solvent removal without long extraction times
Solution Approach 2:
The patent transitions from one-dimensional batch soaking (particles immersed in stationary liquid) to three-dimensional continuous flow through a column (liquid moving vertically through packed particles). This dimensional change creates continuous fresh contact between extraction medium and particles, eliminating the equilibration limitation of batch processes and enabling rapid solvent recovery
3Manufacturing precision
If large amounts of leaching liquid are used to reach low residual solvent contents, then solvent recovery is achieved, but the process becomes water-intensive and increases wastewater treatment load
Solution Approach 1:
The continuous flow extraction maintains constant concentration gradients by continuously replenishing fresh extraction medium at the column inlet and removing solvent-enriched medium at the outlet. This continuous action achieves low residual solvent concentrations in particles using significantly less total extraction medium volume compared to batch processes that require multiple cycles with fresh liquid
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 process significantly reduces water usage and extraction time while achieving low residual solvent concentrations in cellulosic particles, enhancing the efficiency and environmental sustainability of solvent recovery.
Implementation Method 1
the transport of solvent from the cellulosic particles to the extraction medium is dominated by an equilibration effect, thus the concentrations of solvent inside the cellulosic particles and in the extraction medium tend to equalize with time, as the solvent—driven by a concentration gradient—slowly diffuses from the core to the outer shell of the cellulosic particles
Implementation Method 2
due to the continuous flow of extraction medium through the extraction reactor, a constant supply of fresh extraction medium to the cellulosic particles may be provided. This ensures, that the difference between concentrations of solvent in the extraction medium and in the cellulosic particles is maximized at all times, leading to a steep concentration gradient from the cellulosic particles to the extraction medium
Data Source
AI summary
A process (100) for the recovery of solvent (1) from solvent-containing cellulosic particles (2) is shown, the process comprising the steps: a) extracting the solvent (1) from the cellulosic particles (2) by means of a liquid extraction medium (3), thereby obtaining a solvent-enriched extraction medium (5), and b) obtaining the recovered solvent (6) from the solvent-enriched extraction medium (5). In order to improve the efficiency of the process, it is proposed that in step a) the solvent (1) is extracted from the cellulosic particles (2) in a continuous flow extraction reactor (4), wherein the extraction medium (3) continuously flows through the extraction reactor (4) to extract the solvent (1) from the cellulosic particles (2).