Supercritical CO2 Extraction for Low Volatile Carbonaceous Material
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Solution Overview
Problem
Current methods for devolatilizing carbonaceous materials, such as coal, require high energy and do not effectively recover volatile compounds, which are valuable resources, often venting them to the atmosphere or using hazardous solvents for extraction.
Innovation Solution
The use of supercritical CO2 to extract volatile compounds from treated carbonaceous materials, producing a clean devolatilized coal and recovering valuable volatile compounds like coal tar, which can be distilled into carbon pitch for carbon fiber production, while also generating high-quality activated carbon.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If thermal processes (coking or calcining) are used to remove volatile compounds, then volatility is reduced, but energy consumption increases and volatile compounds are lost
Solution Approach 1:
The patent changes the physical state parameter of CO2 from gaseous to supercritical state by increasing pressure above its critical point (73 atm). This parameter change enables CO2 to act as an effective extraction solvent at relatively low temperatures, avoiding the high energy consumption of thermal coking (500°C) and calcining (1,300°C) processes while still achieving effective removal of volatile compounds from coal
Solution Approach 2:
The patent introduces supercritical CO2 as an intermediary substance to facilitate the removal of volatile compounds from coal. Instead of directly heating coal to high temperatures, supercritical CO2 acts as a mediator that extracts volatile compounds through solvation, thereby reducing the energy input required while achieving the desired devolatilization effect
2Stability of the object's composition
If thermal processes are used to remove volatile compounds, then volatility is reduced, but volatile compounds are vented to atmosphere or gas scrubber
Solution Approach 1:
The patent implements a recovery system where volatile compounds extracted by supercritical CO2 are not discarded but recovered through separation processes. The CO2 is depressurized to return to gaseous state, allowing the volatile compounds to be collected and reused, thereby preventing loss of valuable substances while achieving devolatilization
Solution Approach 2:
The patent establishes a feedback loop where the extracted volatile compounds are separated from the CO2 and the CO2 is recycled back into the extraction system. This feedback mechanism ensures continuous operation while preventing loss of volatile compounds, as they are captured and can be fed back into the process or utilized elsewhere
3Loss of substance
If organic solvents are used to extract volatile compounds, then volatile compounds are removed, but hazardous materials and safety expenses increase
Solution Approach 1:
The patent replaces expensive and hazardous organic solvents with CO2, which is inexpensive, non-toxic, and environmentally benign. Although CO2 must be continuously pressurized and depressurized, its safety profile eliminates the need for expensive safety infrastructure required for handling hazardous organic solvents, reducing overall operational costs and safety expenses
Solution Approach 2:
The patent uses CO2 to create an inert extraction environment that is non-flammable and non-toxic, eliminating the fire and health hazards associated with organic solvents. This inert atmosphere approach allows for safe extraction operations without requiring extensive safety devices and measures that would be necessary when using hazardous organic solvents
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 method efficiently devolatilizes carbonaceous materials with lower energy consumption, recovers valuable volatile compounds, and produces clean, high-quality coal products, reducing environmental impact and operational costs.
Implementation Method 1
The use of supercritical CO2 to extract volatile compounds from treated carbonaceous materials
Implementation Method 2
supercritical CO2 that extracts volatile compounds from the treated coal
Implementation Method 3
Recovery and removal of the solvent and the tar or pitch phase occurs upon reduction of the pressure
Data Source
AI summary
A system for making low volatile carbonaceous material including a digestion vessel in communication with a carbonaceous material feedstock unit for producing a digested carbonaceous material; an extraction vessel in communication with the digestion vessel, the extraction vessel containing supercritical carbon dioxide fluid for extracting hydrocarbons from the digested carbonaceous material to produce an extract solvent and the low volatile carbonaceous material; and at least one separation vessel in communication with the extraction vessel for separating the extract solvent to a carbon dioxide gas and a stream of extracted hydrocarbons.