CO2 Purification Heat Pump Cycle for Light and Heavy Impurity Removal
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Solution Overview
Problem
Conventional processes for purifying crude carbon dioxide are inefficient in removing both 'light' and 'heavy' impurities, often requiring external refrigerant systems and consuming excessive energy, while also compromising the overall recovery of carbon dioxide.
Innovation Solution
A process involving indirect heat exchange to cool crude carbon dioxide, followed by mass transfer separation in multiple column systems using a heat pump cycle with carbon dioxide as the working fluid, allowing for simultaneous removal of 'light' and 'heavy' impurities without external refrigeration, reducing energy consumption, and improving carbon dioxide recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If conventional distillation processes are used to remove heavy impurities from carbon dioxide, then hydrogen sulfide removal is achieved, but external refrigerant systems are required and energy consumption is excessive
Solution Approach 1:
The patent combines the refrigeration cycle and distillation process into a single integrated system where the refrigerant serves dual purposes: cooling the feed gas and providing reboil duty for the distillation column through heat exchange, thereby eliminating the need for separate external refrigerant systems and reducing overall energy consumption
Solution Approach 2:
The refrigerant in the patent performs multiple functions simultaneously: it acts as a cooling medium for the crude carbon dioxide feed, serves as a heating medium for the reboiler through heat exchange, and maintains the temperature gradient necessary for distillation, making the system more efficient by eliminating redundant equipment
2Object-generated harmful factors
If conventional distillation processes are used to purify carbon dioxide, then impurity removal is achieved, but external refrigerant systems are required, increasing device complexity
Solution Approach 1:
The patent merges the refrigeration system and distillation column into a single integrated unit where heat exchange between the refrigerant and process streams occurs within the distillation system itself, eliminating the need for separate external refrigerant equipment and simplifying the overall device configuration
Solution Approach 2:
The distillation system serves its own refrigeration needs by using the refrigerant cycle integrated within the column to provide both cooling for the feed and heating for the reboiler, making the system self-sufficient and eliminating dependence on external refrigerant systems
3Object-generated harmful factors
If conventional distillation processes are used for carbon dioxide purification, then impurity removal is achieved, but overall recovery of carbon dioxide is compromised
Solution Approach 1:
The patent operates the distillation column at elevated pressures (e.g., 73-100 atm) which changes the phase behavior and volatility relationships of carbon dioxide and impurities, allowing for more efficient separation that maximizes carbon dioxide recovery while effectively removing impurities, thereby reducing loss of the valuable carbon dioxide substance
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 process significantly reduces energy consumption, enhances carbon dioxide recovery, and simplifies the purification process by eliminating the need for external refrigerant systems while maintaining or improving purity, thereby achieving more efficient impurity removal.
Implementation Method 1
The re-boiling is effected by a heat pump cycle which uses purified carbon dioxide as the working fluid. The working fluid is passed through a compressor, a heat exchanger and a re-boiler immersed in the bottoms liquid, where it is condensed before being fed back to the top of the column as reflux.
Implementation Method 2
The carbon dioxide overhead vapor is condensed using an external closed cycle of ammonia refrigerant
Implementation Method 3
The gaseous mixture is compressed, cooled and condensed and fed to a distillation column where it is separated into a high purity (at least 99.95%) carbon dioxide overhead vapor and a bottoms liquid containing condensed sulfur-containing gases.
Data Source
AI summary
In a process for separating at least one “heavy” impurity such as hydrogen sulfide from crude carbon dioxide comprising significant quantities of at least one “light” impurity such as non-condensable gases, involving at least one heat pump cycle using carbon dioxide-containing fluid from the process as the working fluid, the “light” impurity is removed from the crude carbon dioxide and carbon dioxide is subsequently recovered from the removed “light” impurity, thereby improving overall carbon dioxide recovery and efficiency in terms of energy consumption.