CO2 Purification Column With Internal Refrigeration at High Pressure
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Solution Overview
Problem
Current carbon dioxide purification processes from oxyfuel combustion and hydrogen PSA processes face challenges in achieving high carbon dioxide recovery and purity, particularly in reducing oxygen and other contaminant levels, while being energy-efficient and cost-effective.
Innovation Solution
A method involving a mass transfer separation column system that uses internal refrigeration through indirect heat exchange between process streams to separate and purify carbon dioxide, reducing oxygen and other contaminants to below 100 ppm, and producing a high-purity carbon dioxide product as a liquid at pressures below its critical pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If contaminant gases are removed from compressed carbon dioxide by cooling to near freezing point, then carbon dioxide purity is improved, but energy consumption increases and carbon dioxide recovery is limited to about 90%
Solution Approach 1:
The invention changes the operating parameters by conducting separation at elevated pressures (73-300 bar) rather than at atmospheric pressure. This pressure change fundamentally alters the phase behavior and equilibrium conditions, enabling high-purity separation with superior energy efficiency and recovery rates compared to conventional low-temperature methods.
Solution Approach 2:
The invention utilizes phase transitions of carbon dioxide in a controlled manner at elevated pressures. By operating above the critical pressure of CO2 and controlling temperature variations, the process exploits gas-liquid equilibrium and phase separation to achieve contaminant removal while maintaining high recovery rates, avoiding the energy-intensive near-freezing conditions of conventional methods.
2Device complexity
If single-stage purification at about 30 bar is used, then process simplicity is maintained, but carbon dioxide recovery is limited to about 90% and purity specifications are not fully met
Solution Approach 1:
The invention segments the purification process into distinct operational stages within a continuous flow system. The process divides contaminant removal into sequential steps (water condensation, CO2 separation, further purification) that occur at different conditions, achieving high recovery and purity while maintaining operational simplicity through integrated design.
Solution Approach 2:
The invention adds the pressure dimension to the purification process by operating at elevated pressures (73-300 bar) rather than at atmospheric pressure. This dimensional change enables new separation mechanisms and equilibrium conditions that simultaneously improve recovery rates and purity while maintaining process simplicity.
3Use of energy by moving object
If oxygen and nitrogen are not removed to below 100 ppm, then energy consumption is reduced, but carbon dioxide purity specification of at least 97 mol% is not met
Solution Approach 1:
The invention maintains continuous operation at elevated pressures throughout the purification process, eliminating the need for energy-intensive cooling and reheating cycles. The continuous flow system with integrated separation stages achieves sustained high-purity output (≥97 mol% CO2) with minimal energy input by keeping the process in a steady-state high-pressure regime.
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 achieves carbon dioxide recovery of over 97% with a purity of at least 97 mol%, minimizing energy consumption and enabling efficient transportation and storage of carbon dioxide as a liquid or supercritical fluid.
Implementation Method 1
separating impure liquid carbon dioxide in a mass transfer separation column system to produce first contaminant-enriched overhead vapor and carbon dioxide-enriched bottoms liquid
Implementation Method 2
cooling at least a portion of the cooled crude carbon dioxide fluid by indirect heat exchange to produce partially condensed crude carbon dioxide fluid
Implementation Method 3
phase separating at least a portion of the partially condensed crude carbon dioxide fluid to produce the impure liquid carbon dioxide and carbon dioxide-depleted vapor
Implementation Method 4
compressing the carbon dioxide gases to form compressed carbon dioxide gas
Data Source
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AI summary
A first contaminant selected from oxygen and carbon monoxide is removed from impure liquid carbon dioxide using a mass transfer separation column system C104 which is reboiled by indirect heat exchange against crude carbon dioxide fluid, the impure liquid carbon dioxide having a greater concentration of carbon dioxide than the crude carbon dioxide fluid. The invention has particular application in the recovery of carbon dioxide from flue gas generated in an oxyfuel combustion process or waste gas from a hydrogen PSA process. Advantages include reducing the level of the first contaminant to not more than 1000 ppm.