Continuous Supercritical Drying of Aerogel Particles Without Valves
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Solution Overview
Problem
Existing processes for the continuous supercritical drying of gel particles, particularly for producing aerogels, face challenges such as high apparatus expense, high material consumption, and slow decompression rates, especially when using carbon dioxide as the supercritical fluid, which are not suitable for temperature-sensitive materials.
Innovation Solution
A process involving the introduction of a gel suspension into a column where carbon dioxide flows in countercurrent, allowing for continuous, valve-free decompression of aerogel particles by setting the pressure and temperature to be supercritical or virtually supercritical, using a capillary system to facilitate sedimentation and removal of particles without the need for valves, and employing staged decompression with temperature adjustments to manage the Joule-Thomson effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If continuous decompression via valves is used, then decompression speed is improved, but valve abrasion and blocking occur
Solution Approach 1:
The invention extracts the decompression function from the valve system and relocates it to the outlet flow regulation device. By controlling the outlet flow rate to be less than the feed flow rate, continuous decompression is achieved without requiring valves to be in direct contact with the particle-fluid stream, thereby eliminating valve abrasion and blocking while maintaining fast decompression speed.
Solution Approach 2:
The outlet flow regulation device acts as an intermediary mechanism between the pressurized reactor and the ambient environment. It mediates the decompression process by controlling the outlet flow rate, enabling gradual pressure reduction without the mechanical wear and blocking issues associated with traditional valve systems.
2Productivity
If high pressure and temperature are used for supercritical drying, then drying efficiency is improved, but energy consumption increases
Solution Approach 1:
The invention implements continuous supercritical drying where gel particles are continuously fed into the reactor and dried aerogel particles are continuously discharged. This continuous operation eliminates the heating and cooling cycles associated with batch processing, maintaining steady-state supercritical conditions and significantly reducing energy consumption while improving drying efficiency.
Solution Approach 2:
The invention replaces the traditional batch drying mechanism with a continuous flow system driven by fluid dynamics rather than mechanical heating/cooling cycles. The continuous countercurrent flow of supercritical fluid through the gel particles enables efficient mass and heat transfer without the energy-intensive thermal cycling of batch processes.
3Device complexity
If batch decompression is used, then equipment complexity is reduced, but production time increases
Solution Approach 1:
The invention transforms the batch decompression process into a continuous operation. Gel particles are continuously fed into the supercritical reactor, dried in place, and discharged continuously as aerogel particles. This eliminates the repeated heating and cooling cycles of batch processing, dramatically reducing production time while maintaining relatively simple equipment through continuous countercurrent flow.
4Ease of manufacture
If conventional drying is used, then process simplicity is improved, but particle shrinkage and loss of porous structure occur
Solution Approach 1:
The invention changes the physical parameters of the drying fluid to supercritical conditions (temperature and pressure above critical point). In this state, the fluid exhibits properties that eliminate surface tension and interfacial forces, allowing solvent removal without capillary pressure that would cause particle shrinkage. This maintains the porous structure while keeping the process relatively simple and continuous.
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 enables rapid, gentle drying of gel particles, including temperature-sensitive materials, with reduced energy consumption and apparatus costs, producing high-porosity aerogel particles suitable for various applications.
Implementation Method 1
introducing the suspension into a column through which carbon dioxide flows in countercurrent
Implementation Method 2
the pressure and temperature in the column are set such that the mixture of carbon dioxide and solvent is virtually supercritical or is supercritical
Implementation Method 3
the interfacial tension of the fluid present in the mesoporous particles is completely or largely eliminated with the aim of largely preventing shrinking of the mesoporous and macroporous particles on drying
Implementation Method 4
using a capillary system to facilitate sedimentation and removal of particles without the need for valves
Implementation Method 5
employing staged decompression with temperature adjustments to manage the Joule-Thomson effect
Data Source
AI summary
Processes for drying gel particles, in particular for producing aerogels, involve providing a suspension containing gel particles and a solvent, introducing the suspension into a column where carbon dioxide flows in countercurrent, and removing dried aerogel particles from the column. The suspension is introduced in the top region of the column and dried aerogel particles are removed in the lower region. Pressure and temperature in the column are set such that the mixture of carbon dioxide and solvent is virtually supercritical or is supercritical. The aerogel particles can be discharged via discharge vessels or continuous decompression. Aerogel particles can be obtained by such a process and the aerogel particles can be used for medical and pharmaceutical applications, as additive or carrier material for additives for foods, as catalyst support, for cosmetic, hygiene, washing and cleaning applications, for production of sensors, for thermal insulation, or as a core material for VIPs.