Multi-Stage CO₂ Liquefaction Process for Food-Grade Purity
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Solution Overview
Problem
Existing methods for recovering and purifying carbon dioxide from carbon dioxide-rich gases are inefficient and do not produce carbon dioxide of high enough purity for food or pharmaceutical use, and they do not effectively recycle other components of the gas.
Innovation Solution
A method involving activated carbon filtration, multiple cooling stages, gas overpressure, compression, filtration, drying, and distillation steps to produce high-purity liquid carbon dioxide, along with a device comprising filtration units, heat exchangers, a booster, compressor, and distillation column to achieve this.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If existing purification methods are used, then carbon dioxide can be recovered, but the purity is not high enough for food or pharmaceutical use
Solution Approach 1:
The purification process is divided into multiple sequential stages: activated carbon filtration to remove organic contaminants, molecular sieve filtration to remove water and other gases, and fractional distillation to separate carbon dioxide from remaining impurities. Each stage targets specific contaminants, progressively achieving food-grade and pharmaceutical-grade purity levels.
Solution Approach 2:
Different filtration and separation techniques are applied at different stages of the process to address specific contamination issues. Activated carbon is used for organic compounds, molecular sieves for water vapor, and distillation for final purification. Each method is optimized for its specific function to achieve the required purity levels.
2Loss of substance
If existing purification methods are used, then carbon dioxide can be recovered, but energy consumption is high
Solution Approach 1:
The process performs preliminary cooling of the carbon dioxide-rich gas before compression and distillation. By pre-cooling the gas, the subsequent compression and phase change require less energy. The system also recycles cold streams to pre-cool incoming gas, reducing overall energy consumption.
Solution Approach 2:
The process utilizes phase transitions of carbon dioxide (gas to liquid to gas) as the primary separation mechanism. By controlling temperature and pressure to induce phase changes, the system achieves efficient separation of carbon dioxide from impurities with lower energy consumption compared to continuous high-temperature methods.
3Manufacturing precision
If existing methods are used, then carbon dioxide can be purified, but other gas components are not effectively recycled
Solution Approach 1:
The process extracts and removes carbon dioxide from the mixed gas stream through selective phase transition and distillation. The remaining gas components (methane, nitrogen, oxygen, etc.) are separated as a distinct stream and can be independently processed or recycled back to the methanization process or other appropriate uses.
Solution Approach 2:
The system is designed to recover carbon dioxide in high-purity form for valuable applications while the other gas components are either discarded in a controlled manner or recovered for reuse. The distillation column and separation systems enable selective recovery of different components based on their volatility and phase behavior.
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 method achieves carbon dioxide of food or pharmaceutical grade purity with low energy consumption, and the device allows for efficient recovery and recycling of other gas components.
Implementation Method 1
one or more activated carbon filtration steps
Implementation Method 2
one or more gas cooling steps, the temperature of the gas at the outlet of this step being between 10 and 20°C
Implementation Method 3
a gas compression step, the pressure of the gas at the outlet of this step being between 15 and 25 bar
Implementation Method 4
a gas drying step
Implementation Method 5
a fluid distillation step so as to isolate the liquefied carbon dioxide
Implementation Method 6
a gas liquefaction step, the fluid at the outlet of this step being at a temperature between -25°C and -35°C
Data Source
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AI summary
This disclosure relates to a process for producing liquid carbon dioxide from a gas containing more than 70% by volume of carbon dioxide, comprising the following successive steps: one or more activated carbon filtration steps followed by one or more gas cooling steps, the gas temperature at the outlet of this step being between 10 and 20°C, then a gas overpressure step, the gas pressure at the outlet of this step being between 1.05 and 1.40 bar, one or more gas cooling steps, then a gas compression step, the gas pressure at the outlet of this step being between 15 and 25 bar, then one or more filtration steps followed by a gas drying step, then one or more filtration steps followed by a gas liquefaction step, the fluid at the outlet of this step being at a temperature between -25°C and -35°C.then a distillation step of the fluid to isolate the liquefied carbon dioxide, a recovery step of the carbon dioxide in liquid form from step j), a liquefaction step of the gas recovered at the top of the distillation column in step j), the gas exiting this step being at a temperature between -35°C and -45°C, then a separation step of the liquid phase from the gaseous phase of the fluid from the liquefaction step I), then a recycling step of the liquid phase from the separation of step m) to the distillation step j).