Gas Loop Reactor for Uniform Wood Acetylation and Low Corrosion
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Solution Overview
Problem
Existing acetylation processes for solid wood face challenges such as equipment corrosion, high energy consumption for chemical recovery, and inefficiency in processing large wood pieces due to hazardous conditions and non-uniform heat and mass transfer.
Innovation Solution
A reactor system with a gas flow loop connected to a heat exchanger and fan outside the reactor, allowing gas circulation over the diameter of the vessel, and a process involving gas circulation for acetylation and chemical recovery, using a portion of the gas for condensation to minimize energy input.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If standard equipment is used for acetylation of solid wood in liquid phase, then acetylation can be achieved, but equipment corrosion occurs due to corrosive acetylation liquid under elevated temperature and pressure
Solution Approach 1:
The fan is extracted from the reaction vessel and placed in the gas flow loop outside the vessel. This separation removes the fan from direct contact with the corrosive acetylation liquid while maintaining its function of circulating gas through the vessel for heat transfer and mass transfer during acetylation.
Solution Approach 2:
A gas flow loop acts as an intermediary medium between the heating source and the wood material. The gas circulates through the heat exchanger and then through the reaction vessel, transferring heat without requiring direct contact between heating elements and the corrosive liquid environment.
2Loss of substance
If stripping gas is used to remove acetylation medium from wood, then chemical recovery is achieved, but high energy input is required
Solution Approach 1:
The circulating gas in the gas flow loop serves dual purposes: it provides heat transfer during acetylation and subsequently acts as the stripping gas for chemical recovery. The gas that has already been heated and circulated through the system is reused for stripping, eliminating the need for separate high-energy stripping operations.
Solution Approach 2:
The gas circulation continues throughout the process without interruption. The same gas flow that facilitates heat and mass transfer during acetylation transitions into the stripping phase, maintaining continuous useful action and avoiding energy-intensive intermediate steps.
3Manufacturing precision
If liquid acetylation medium is used for solid wood, then effective acetylation is achieved, but non-uniform heat and mass transfer occurs in large wood pieces
Solution Approach 1:
Gas circulation is used instead of liquid circulation for heat transfer. The gas flow loop with fan creates uniform gas distribution throughout the reaction vessel, enabling more uniform heat and mass transfer to large wood pieces compared to liquid phase methods.
Solution Approach 2:
The system transitions from static liquid immersion to dynamic gas circulation. The moving gas flow actively penetrates the wood material, creating more uniform heat and mass transfer conditions that adapt to the geometry of large wood pieces.
4Ease of operation
If fans are placed inside the reaction vessel for gas circulation, then fluid circulation is achieved, but fan service life is reduced due to exposure to corrosive acetylation liquid
Solution Approach 1:
The fan is extracted from the reaction vessel and positioned in the gas flow loop outside the vessel. This spatial separation maintains the fan's ability to circulate gas through the vessel while protecting it from exposure to corrosive acetylation liquid, thereby extending its service life.
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
Enhances uniform heat and mass transfer, reduces equipment corrosion, and optimizes chemical recovery, making the process more efficient and safer for acetylation of large wood pieces.
Implementation Method 1
said gas flow line connected to a heat exchanger
Implementation Method 2
at least one fan, the use being for an acetylation process wherein solid wood is submerged into a liquid acetylation medium
Implementation Method 3
a process for the acetylation of lignocellulosic material
Data Source
AI summary
A reactor system for the modification of lignocellulosic materials comprises a reaction vessel, a vacuum connection and an inlet and/or outlet connected to a gas flow loop connected to a heat exchanger and at least one fluid circulation device. Particularly, gas flow loop is arranged so as to allow gas circulation over the diameter of the reaction vessel. The gas flow loop preferably includes a gas distribution device, such as a distribution plate.