Rotary Moving Bed for Isothermal CO2 Separation
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Solution Overview
Problem
Current CO2 capture technologies from combustion flue gases are inefficient due to low CO2 concentrations and pressures, leading to high energy consumption and costs, particularly in post-combustion CO2 capture, where CO2 is present at low pressures and concentrations, necessitating significant energy for separation and compression.
Innovation Solution
A rotary moving bed system employing a sorbent with an alkalized substrate, such as alkalized alumina, that uses a combination of concentration swing and desorptive displacement with steam for CO2 adsorption and desorption, maintaining essentially isothermal conditions and constant pressure, thereby reducing energy requirements and costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional absorption process is used for CO2 capture from flue gas, then CO2 separation can be achieved, but energy consumption and cost increase significantly due to low CO2 pressure and concentration
Solution Approach 1:
The invention changes the operating parameters from conventional isobaric or temperature-swing processes to an isothermal process operating at constant pressure. This eliminates the energy-intensive compression steps required in conventional processes while maintaining effective CO2 separation through controlled sorbent regeneration at constant temperature and pressure
Solution Approach 2:
The invention employs a dynamic rotary moving bed system where the sorbent continuously moves between adsorption and desorption zones. This dynamic approach allows continuous CO2 capture and regeneration without the intermittent cycling required in conventional processes, maintaining steady-state operation that reduces energy consumption
2Reliability
If aqueous amines are used for CO2 capture in PC power plants, then CO2 capture can be achieved, but the cost of electricity increases from 64 cents/kWh to 118.8 cents/kWh
Solution Approach 1:
The invention extracts the CO2 separation function from the costly aqueous amine absorption process by using a solid sorbent material that selectively captures CO2 through adsorption. This eliminates the need for energy-intensive thermal regeneration of liquid amines, dramatically reducing the cost of electricity while maintaining CO2 capture capability
Solution Approach 2:
The invention replaces the chemical absorption mechanism of aqueous amines with a physical adsorption mechanism using solid sorbent materials. This substitution eliminates the need for high-temperature thermal regeneration processes, reducing energy consumption and electricity cost from 64 cents/kWh to 118.8 cents/kWh
3Reliability
If pressure swing adsorption is used for CO2 regeneration, then CO2 desorption can be achieved, but high energy consumption is required due to vacuum requirements
Solution Approach 1:
Instead of using pressure reduction (vacuum) to drive CO2 desorption as in conventional PSA, the invention inverts the approach by maintaining constant pressure and using a moving bed configuration where fresh sorbent continuously replaces regenerated sorbent. This eliminates the need for energy-intensive vacuum systems while achieving complete CO2 desorption
4Reliability
If temperature swing adsorption is used for CO2 separation, then CO2 capture can be achieved, but significant thermal energy is required for heating and cooling cycles
Solution Approach 1:
The invention uses periodic movement of the sorbent bed through adsorption and desorption zones rather than periodic thermal cycling. The sorbent is continuously regenerated in a desorption zone and then moved to the adsorption zone, creating a periodic but isothermal process that eliminates the thermal energy losses associated with heating and cooling cycles
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 system effectively captures and recovers CO2 with reduced energy consumption and costs, achieving high CO2 recovery rates while maintaining process efficiency and minimizing the need for external thermal management.
Implementation Method 1
passing a CO2 feed stream into a CO2 feed stream inlet of a rotary moving bed and collecting a CO2-depleted feed stream at a CO2 feed stream outlet
Implementation Method 2
passing a regeneration stream into a regeneration stream inlet of the rotary moving bed and collecting a CO2-enriched stream at a regeneration stream outlet
Data Source
AI summary
A rotary moving bed and process for separating a carbon dioxide from a gas stream is disclosed. The rotary moving bed can have a rotational assembly rotating on a vertical axis, and a plurality of sorbent cells positioned horizontally to the axis of rotation that fills a vertical space in the moving bed, where the sorbent cells adsorb the carbon dioxide by concentration swing adsorption and adsorptive displacement. The sorbent can be regenerated and the carbon dioxide recaptured by desorbing the carbon dioxide from the sorbent using concentration swing adsorption and desorptive displacement with steam. The gas flows in the system flow in a direction horizontal to the axis of rotation and in a direction opposite the rotational movement of the sorbent cells.