Ca(OH)2 Air Contactor Layout for Low-Energy CO2 Carbonation
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Solution Overview
Problem
Existing Direct Air Capture (DAC) systems using calcium hydroxide (Ca(OH)2) for CO2 capture face challenges such as high energy consumption, inefficient carbonation rates, and non-homogeneous carbonation conversions leading to increased costs and reduced mechanical properties of carbonated materials, which hinder their use in construction applications.
Innovation Solution
A method involving the use of dry porous Ca(OH)2 solid forms, such as bricks or bags, stacked to create aligned air channels, displaced countercurrently at low velocities (0.005-0.05 m/h) in an air contactor device, with controlled humidity to achieve homogeneous carbonation and reduce energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high air velocities are used in the air contactor device, then CO2 capture efficiency is improved, but pressure drop increases leading to higher energy consumption
Solution Approach 1:
The air contactor device is divided into multiple stages or zones with different air velocity conditions. The device segments the carbonation process into regions where air velocity is optimized for different purposes: higher velocities in regions needing rapid CO2 capture, and lower velocities in regions where pressure drop control is critical. This segmentation allows the system to achieve high overall CO2 capture efficiency while maintaining acceptable energy consumption levels.
2Productivity
If air channel geometry is optimized for high CO2 capture, then capture efficiency improves, but device complexity increases
Solution Approach 1:
The air contactor device employs local quality optimization where different sections of the device have differently optimized air channel geometries tailored to local requirements. Entrance regions may have geometries optimized for high CO2 capture efficiency, while other regions have simpler geometries. This allows the system to achieve high overall capture efficiency without requiring complex geometries throughout the entire device, thereby reducing overall device complexity while maintaining performance.
3Loss of time
If non-homogeneous carbonation occurs, then processing time is reduced, but mechanical properties of carbonated materials deteriorate
Solution Approach 1:
The air contactor device implements dynamic control of air flow and carbonation conditions to achieve homogeneous carbonation throughout the material. The system dynamically adjusts air velocity, flow distribution, and contact time to ensure uniform CO2 penetration and reaction progress across all regions of the carbonated material. This dynamic optimization allows the system to maintain acceptable processing times while achieving the homogeneous carbonation distribution required for good mechanical properties.
4Strength
If additional processing steps are added to improve carbonation quality, then mechanical properties improve, but device complexity and energy consumption increase
Solution Approach 1:
The air contactor device is designed to achieve homogeneous carbonation and good mechanical properties through its inherent design and operation, without requiring additional post-processing steps. The device self-regulates air flow distribution, contact time, and reaction conditions to produce uniformly carbonated material with acceptable mechanical properties directly from the carbonation process. This self-service approach eliminates the need for additional processing steps, thereby avoiding increases in device complexity and energy consumption while still achieving the desired mechanical quality.
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 approach enhances carbonation efficiency, reduces energy costs, and produces carbonated solid forms with consistent mechanical properties suitable for construction use, minimizing the need for additional processing and resource extraction.
Implementation Method 1
a method of capturing CO2 from the atmosphere using solid forms of calcium hydroxide, preferably dry Ca(OH)2 to form CaCO3
Implementation Method 2
using solid forms of calcium hydroxide, preferably dry Ca(OH)2 to form CaCO3
Implementation Method 3
the air is forced to flow through the air channels created when aligning the solid forms with the direction of the airflow
Implementation Method 4
with controlled humidity to achieve homogeneous carbonation
Data Source
AI summary
This invention discloses a method of capturing CO2 from air using solid forms of calcium hydroxide, preferably dry Ca(OH)2 to form CaCO3. The method is characterized by the use of Ca(OH)2 solid forms stacked in an air contactor device so that the air is forced to flow through the air channels created when aligning the holes of the solid forms with the direction of the airflow. The solids are displaced at an average velocity of 0.005 to 0.05 m/hour. The invention also relates to a method of removing CO2 from the atmosphere and air contactor device configured to carry out the method of capturing CO2.