High Density Carbon from Coal via Controlled Pressure Heating
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Solution Overview
Problem
Current methods for producing high-density carbon materials are costly and inefficient, as they require multiple processing steps and result in low-density, porous carbons, with commercially available three-dimensional self-supporting carbons being either prohibitively expensive or lacking in graphitic character.
Innovation Solution
A direct method of producing high-density, self-supporting carbon from coal by heating comminuted bituminous coal under controlled pressure and temperature conditions, eliminating swelling and achieving a continuous carbon matrix with graphitic character, which can be further graphitized to enhance properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If traditional methods are used to produce high-density carbon materials through multiple processing steps including pulverizing, mixing with binder, forming, and repeated pitch impregnation, then the carbon material achieves higher density, but the manufacturing complexity and cost increase significantly
Solution Approach 1:
The coal is comminuted and prepared in advance under high pressure (greater than 400 psig) before heating, creating a dense particulate structure that eliminates the need for subsequent binder mixing and forming steps. This preliminary densification action prevents the need for repeated impregnation cycles required in traditional methods.
Solution Approach 2:
The invention extracts and eliminates the binder (pitch) component from the traditional manufacturing process. By using high pressure to densify comminuted coal directly, the process removes the need for adding external binders and performing repeated impregnation steps, simplifying the overall manufacturing complexity while achieving high density.
2Productivity
If coal is heated rapidly to high temperatures, then the carbonization process is faster and more efficient, but the coal particles swell and form porous structures with lower density
Solution Approach 1:
High pressure (greater than 400 psig) is applied to the comminuted coal before and during the heating process to counteract the swelling tendency of coal particles. This preliminary anti-action prevents the formation of porous structures that would otherwise occur during rapid heating, allowing fast carbonization while maintaining high density.
Solution Approach 2:
The invention changes the pressure parameter from atmospheric or low pressure to high pressure (greater than 400 psig) during the carbonization process. This parameter change fundamentally alters the coal's response to heating, preventing swelling and pore formation while allowing rapid heating to achieve high carbonization speed and density simultaneously.
3Quantity of substance
If multiple pitch impregnation and re-heating cycles are performed to increase carbon density, then the density improves, but the manufacturing time and energy consumption increase
Solution Approach 1:
The invention removes the pitch impregnation step entirely from the manufacturing process. By using high pressure to densify comminuted coal directly, the process achieves high density in a single step without requiring repeated impregnation and re-heating cycles, dramatically reducing manufacturing time.
Solution Approach 2:
The invention combines the densification and carbonization functions into a single integrated process step. High pressure densification of comminuted coal is performed simultaneously with carbonization heating, eliminating the separate, repeated impregnation cycles required in traditional methods and reducing total manufacturing time.
4Strength
If commercial glassy carbons are used to achieve three-dimensional self-supporting structures, then the structural integrity is achieved, but the cost becomes prohibitive for most applications
Solution Approach 1:
The invention uses comminuted coal, a cheap and abundant material, as the feedstock instead of expensive graphitizable coes or glassy carbon precursors. The high pressure densification process transforms this low-cost material into a dense, structurally intact carbon product that is economically viable for most applications.
Solution Approach 2:
The invention applies high pressure (greater than 400 psig) during carbonization to achieve structural integrity without requiring expensive glassy carbon materials. This parameter change enables the production of dense, self-supporting carbon structures from inexpensive comminuted coal, dramatically reducing manufacturing cost while maintaining structural properties.
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 yields carbon materials with densities above 1.0 g/cc, high crush strength, and improved thermal conductivity, offering a cost-effective and efficient route to producing graphitic carbons suitable for various applications, including structural and thermal management uses.
Implementation Method 1
heating a comminuted bituminous coal to a first temperature which is generally below the initial plastic temperature for the coal
Implementation Method 2
The coal is then slowly heated to a second temperature, at a rate sufficiently slow as to substantially prevent swelling of the coal. The heating of the coal is carried out under an environmental pressure significantly greater than atmospheric pressure.
Implementation Method 3
Following preparation, the solidified product may be heated to temperatures as high as about 3000° C. to further carbonize, calcine, or graphitize the carbon material.
Implementation Method 4
Heating the solidified product to temperatures of about 1800° C. or greater produces a graphitized product in which at least a portion of the grains display graphitic character.
Data Source
AI summary
A high density carbon material produced from coal is described. The carbon material may have a density ranging from about 1.0 g/cc to about 1.6 g/cc and may have a crush strength of up to about 20,000 psi. The high density carbon material is produced by slowly heating comminuted swelling bituminous coal particles under pressures of 400 psi to about 500 psi to a first temperature at about the initial plastic temperature of the coal. The material is held at this temperature for a period of time sufficient to provide for a uniform temperature throughout the coal. The material is then heated to a second temperature for a period of time sufficient to provide for the coal achieving an essentially uniform temperature. The resulting product is a three-dimensional, self-supporting carbon that has a substantially continuous carbon matrix defining grain boundaries within the carbon matrix. The characteristics of the carbon material may be altered by further heating to carbonize or graphitize the high density carbon material.