CO2 Purification by Membrane-Distillation Recovery Loop
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Solution Overview
Problem
Current processes for carbon dioxide recovery and purification from gas mixtures, such as boiler flue gas and lime kiln gas, are energy-intensive and inefficient, particularly in achieving high purity and recovery rates without the use of solvents like amines.
Innovation Solution
A process integrating membrane technology and carbon dioxide distillation, where a gas mixture is pretreated, fractionated, and then passed through a membrane selective to carbon dioxide, with the carbon dioxide permeate recycled back into the system, and utilizing carbon dioxide as a self-refrigerant to enhance efficiency and purity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If solvent scrubbing is used to recover carbon dioxide from low carbon dioxide content streams, then carbon dioxide recovery is achieved, but energy consumption increases and the process becomes expensive
Solution Approach 1:
The process segments carbon dioxide recovery into multiple stages: pretreatment to remove contaminants, fractional condensation to separate carbon dioxide from light gases, and selective adsorption on molecular sieves. This segmentation allows each stage to target specific components, improving overall recovery efficiency while reducing the energy intensity compared to single-stage solvent scrubbing
Solution Approach 2:
The process utilizes phase transitions of carbon dioxide and other gases during fractional condensation. By controlling temperature and pressure, carbon dioxide is condensed while lighter gases remain in vapor phase, enabling separation without requiring energy-intensive solvent circulation and regeneration
2Manufacturing precision
If conventional distillation and condensation processes are used to purify carbon dioxide, then high purity carbon dioxide is achieved, but energy consumption increases significantly
Solution Approach 1:
Molecular sieve adsorbents with specific pore sizes are used to selectively adsorb carbon dioxide from the gas mixture. The porous structure of the molecular sieves provides high surface area for selective uptake of carbon dioxide molecules while excluding lighter gases, achieving high purity recovery at lower energy consumption than conventional distillation
Solution Approach 2:
The process changes physical parameters (temperature, pressure) to optimize separation at each stage. By operating at conditions where carbon dioxide exhibits different physical properties compared to light gases, the process achieves high purity separation with reduced energy input compared to maintaining constant high-energy conditions throughout
3Productivity
If carbon dioxide flooding operations are conducted, then enhanced oil recovery is achieved, but carbon dioxide breakthrough requires expensive purification to meet product specifications
Solution Approach 1:
The process performs preliminary removal of contaminants (water vapor, hydrocarbons, nitrogen, carbon monoxide) before the main carbon dioxide recovery stage. This preliminary action ensures that the recovered carbon dioxide meets product specifications for reinjection without requiring additional expensive purification steps
Solution Approach 2:
The process incorporates a recycle stream where gas that does not meet specification is returned to the pretreatment stage for further processing. This feedback mechanism ensures continuous production of high-purity carbon dioxide while minimizing waste, maintaining the purity required for reinjection into oil reservoirs
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 process achieves high purity carbon dioxide recovery rates of over 90% from low carbon dioxide content streams, reducing energy consumption and eliminating the need for solvents, while also enabling heat recovery and desiccant regeneration.
Implementation Method 1
passing the overheads fraction over a membrane selective to carbon dioxide to separate a carbon dioxide permeate from a residue gas comprising the light gases
Implementation Method 2
The carbon dioxide can then be compressed, dried, cooled and further purified by partial condensation or distillation
Implementation Method 3
The carbon dioxide can then be compressed, dried, cooled and further purified by partial condensation or distillation
Data Source
AI summary
A process for the recovery of carbon dioxide from a gas mixture that includes pretreating a gas mixture comprising carbon dioxide, water vapor, and one or more light gases in a pretreating system to form a cooled gas mixture, fractionating the cooled gas mixture to recover a bottoms fraction comprising carbon dioxide and an overheads fraction comprising carbon dioxide and the light gases, passing the overheads fraction over a membrane selective to carbon dioxide to separate a carbon dioxide permeate from a residue gas comprising the light gases, recycling the carbon dioxide permeate to the pretreating system, and recovering at least a portion of the bottoms fraction as a purified carbon dioxide product stream is described.