CO₂ Stream Antifreeze Scrubbing for Low-Cost Compression and Drying
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Solution Overview
Problem
The compression and drying of CO2-rich streams require expensive stainless steel or high-nickel materials to prevent corrosion, and existing methods are inefficient in reducing water content before compression, leading to high costs and energy penalties.
Innovation Solution
Incorporating an antifreeze agent like methanol to lower the freezing point of water, allowing for partial condensation and recycling, which enables the use of carbon or low-alloy steel compressors and reduces the need for expensive drying units by maintaining the dew point below freezing temperatures during compression and cooling stages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If stainless steel or high-nickel materials are used in compressors to prevent corrosion from carbonic acid and other acids, then corrosion resistance is improved, but material cost and device complexity increase significantly
Solution Approach 1:
The invention applies preliminary drying action before compression by using molecular sieve beds to remove water from the CO2-rich stream upstream of the compressor. This pre-drying prevents the formation of corrosive carbonic acid and other acids during compression, thereby eliminating the need for expensive corrosion-resistant materials like stainless steel or high-nickel alloys in the compressor construction.
Solution Approach 2:
The invention extracts and removes water from the CO2-rich stream using molecular sieve adsorption before the compression stage. By taking out the water component that causes corrosion through acid formation, the harmful corrosive environment is eliminated, allowing the use of simpler and less expensive materials in the compressor.
2Quantity of substance
If adsorption drying units are used to remove water from CO2-rich streams before compression, then water content is reduced, but device complexity and capital cost increase
Solution Approach 1:
The invention changes the operational parameters of the molecular sieve drying system by operating at elevated pressures (up to 300 bar) and utilizing temperature swing or pressure swing regeneration cycles. This allows efficient water removal at the required levels while optimizing the size and cost of the drying units through parameter optimization rather than simply adding more drying capacity.
Solution Approach 2:
The invention implements a continuous drying operation using multiple molecular sieve beds operating in sequence - one bed drying the gas while another bed is being regenerated. This continuous operation maintains constant water removal capability without requiring large standby capacities, reducing overall device complexity and capital cost.
3Device complexity
If water is not sufficiently removed before compression, then device complexity is reduced, but corrosion occurs during compression and cooling phases
Solution Approach 1:
The invention applies preliminary drying action before compression by using molecular sieve beds to remove water from the CO2-rich stream upstream of the compressor. This pre-drying prevents the formation of corrosive carbonic acid and other acids during compression, thereby eliminating the need for expensive corrosion-resistant materials like stainless steel or high-nickel alloys in the compressor.
Solution Approach 2:
The invention applies preliminary anti-action by removing water before compression to prevent the harmful corrosive effect from occurring in the first place. By eliminating the water that would form corrosive acids under compression and cooling conditions, the harmful corrosion effect is prevented before it can affect the compressor materials.
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 approach significantly reduces the cost of compression and purification units, stabilizes compressor suction temperatures, and eliminates the need for expensive adsorption drying equipment, while maintaining the efficiency and purity of the CO2 production process.
Implementation Method 1
Incorporating an antifreeze agent like methanol to lower the freezing point of water
Implementation Method 2
allowing for partial condensation and recycling
Implementation Method 3
The essential purpose of this unit is to remove sufficient water from the CO2-rich stream to prevent this water from freezing during cooling in unit 9
Data Source
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AI summary
In a process for compressing a CO2-rich fluid containing water: the CO2-rich fluid is compressed in a compressor (61); upstream of the compression step, an antifreeze is mixed with the CO2-rich fluid containing water; the CO2-rich fluid containing antifreeze is cooled; water is separated from the cooled fluid; and the water-depleted cooled fluid; is compressed in the compressor, characterized in that: the CO2-rich fluid containing water is sent to a scrubbing column (3) fed, preferably at the top, with a water/antifreeze mixture (53), where it cools and is separated from the water, the water-depleted cooled fluid being extracted from the top of the column; a water/antifreeze mixture in the column is extracted at a level below the top; the mixture is cooled using the refrigeration from an apparatus for cooling and/or purifying the cooled fluid (55) compressed in the compressor (61); and the fluid is returned to the top of the column.