Revolving-Drum Wet Concrete Conditioning With Nitrogen Cooling
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Solution Overview
Problem
Existing methods for cooling and carbonating wet concrete are inefficient, cause temperature fluctuations, and introduce logistical delays, particularly when used in large construction processes, and do not effectively manage carbon dioxide emissions.
Innovation Solution
A method involving the simultaneous use of liquid nitrogen and solid or liquid carbon dioxide in a revolving-drum concrete mixer to cool and partially carbonate wet concrete, controlling the carbonation and temperature through regulated ratios and dispersion of carbon dioxide in nitrogen, allowing for rapid conditioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If carbon dioxide is used to cool wet concrete, then cooling effect is achieved, but exothermic carbonation reaction causes temperature increase and chemical changes in concrete
Solution Approach 1:
Liquid nitrogen is used as an intermediary cooling medium between the concrete and carbon dioxide. The nitrogen absorbs heat from the concrete during evaporation, preventing direct exothermic carbonation while achieving cooling. This mediator allows thermal energy transfer without chemical reaction.
Solution Approach 2:
The harmful exothermic carbonation reaction is extracted and separated from the cooling process. Instead of using carbon dioxide in direct contact with concrete, only liquid nitrogen is applied to the concrete surface for cooling, while carbon dioxide is excluded from the immediate cooling zone to prevent unwanted chemical reactions.
2Object-generated harmful factors
If liquid nitrogen is used to cool wet concrete, then cooling effect is achieved without chemical reaction, but additional cooling time is required after carbonation
Solution Approach 1:
The carbonation process and cooling process are merged into a single simultaneous operation. Carbon dioxide is introduced to promote carbonation while liquid nitrogen is introduced concurrently to provide cooling, eliminating the need for sequential processing and reducing total time.
Solution Approach 2:
The cooling action continues throughout the carbonation process rather than being a separate subsequent step. Liquid nitrogen is applied continuously during concrete mixing and carbonation, maintaining cooling throughout the entire process to prevent temperature rise without requiring additional post-carbonation cooling time.
3Loss of substance
If carbon dioxide is introduced to wet concrete, then carbonation occurs to capture emissions, but flowability and workability of concrete are affected
Solution Approach 1:
Carbon dioxide introduction is localized and controlled to specific zones within the concrete mixture rather than uniform distribution. This allows carbonation to occur in targeted areas while preserving workability in other regions, enabling selective carbonation without compromising overall concrete handling properties.
Solution Approach 2:
Partial carbonation is applied rather than complete carbonation of the entire concrete volume. By introducing carbon dioxide at controlled levels and durations, sufficient carbonation is achieved for emission capture purposes while maintaining adequate workability and flowability for construction operations.
4Temperature
If cooling fluid is injected into rotating mixer drum, then cooling is achieved during transport, but dilution of concrete occurs with additional water
Solution Approach 1:
The cooling medium changes phase from liquid to gas (nitrogen evaporation) upon contact with concrete, eliminating liquid dilution. This parameter change allows heat transfer through phase transition without adding liquid volume that would dilute the concrete concentration.
Solution Approach 2:
Liquid nitrogen is used as a disposable cooling agent that evaporates completely after providing cooling. The nitrogen gas disperses and leaves no residual liquid in the concrete, unlike water-based cooling systems that leave behind diluting liquid and require drainage or pumping operations.
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
The method achieves controlled cooling and carbonation with reduced temperature fluctuations, minimizing logistical delays and carbon dioxide emissions, while ensuring homogeneous concrete properties and efficient processing.
Implementation Method 1
liquid nitrogen which contacts the wet concrete at its free surface and thereby cools the wet concrete
Implementation Method 2
carbon dioxide which has thus chemically reacted with the wet concrete, remains in the concrete during and after setting
Implementation Method 3
wet concrete is agitated in a revolving-drum concrete mixer. Such agitation causes changing portions of the wet concrete to be brought to the free surface
Data Source
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AI summary
Method and equipment for conditioning wet concrete (703), the wet concrete (703) being agitated in a revolving-drum concrete mixer (702), thereby bringing changing portions of the wet concrete (703) to a free surface (706) of the wet concrete (703) inside the mixer (702), the agitated wet concrete (703) being cooled and partially carbonated in that liquid and/or solid carbon dioxide is supplied to the concrete mixer (702) simultaneously with liquid nitrogen so that both the supplied nitrogen and the supplied carbon dioxide contact the free surface (706) of the wet concrete (703).