Liquefied CO2 Terminal Vent Gas Injection for Impurity Handling
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Solution Overview
Problem
Existing liquefied CO2 terminals designed for food-grade CO2 struggle to handle impurities such as hydrogen, nitrogen, methane, and carbon monoxide, as traditional reliquefaction methods are infeasible due to low temperatures and high impurity concentrations, leading to CO2 venting and environmental damage.
Innovation Solution
A method involving the compression of gaseous components from a liquefied CO2 storage tank and injection into a high-pressure CO2 pipeline connected to a subterranean storage reservoir, allowing for the dissolution of volatile impurities without venting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional reliquefaction is used to handle boil-off gas from impure liquefied CO2, then CO2 can be recovered, but the process becomes infeasible due to high impurity concentrations causing temperatures to fall below the freezing point of CO2 or requiring venting
Solution Approach 1:
The patent changes the pressure parameter of the system by injecting boil-off gas into a high-pressure pipeline (typically 73-300 bar) connected to the storage reservoir. This pressure increase allows the gas to remain in supercritical or dense phase without freezing, enabling handling of impure CO2 that would otherwise be incompatible with traditional reliquefaction processes
Solution Approach 2:
The high-pressure pipeline acts as an intermediary medium between the boil-off gas and the storage reservoir. By introducing the gas into this high-pressure environment, the system avoids direct contact between impure CO2 and low-temperature equipment, preventing freezing issues while still achieving storage
2Manufacturing precision
If distillation is used to remove impurities before reliquefaction, then CO2 purity is improved, but the process becomes energy-intensive and requires additional equipment
Solution Approach 1:
Instead of using complex distillation equipment to remove impurities, the patent extracts only the necessary action: injecting the boil-off gas directly into the high-pressure pipeline. The impurities are effectively separated from the liquid CO2 phase through the phase separation in the pipeline, eliminating the need for additional purification equipment
Solution Approach 2:
The system uses the existing high-pressure pipeline and storage reservoir conditions to automatically separate and handle impurities. The high-pressure environment causes volatile impurities to remain in gas phase while CO2 transitions to liquid or supercritical phase, achieving purification without external intervention or additional equipment
3Loss of substance
If pressure swing adsorption is used to prevent CO2 venting, then CO2 retention is improved, but impurities are still vented which causes environmental damage
Solution Approach 1:
The high-pressure pipeline serves multiple functions simultaneously: it transports liquid CO2 to the storage reservoir, provides a high-pressure environment for boil-off gas injection, and acts as a separation medium that retains both CO2 and impurities in the subsurface reservoir. This eliminates the need for separate CO2 retention and impurity handling systems
Solution Approach 2:
The presence of impurities in the boil-off gas, which would normally be harmful, is converted into a benefit. The high-pressure injection method allows these impurities to be co-injected with the CO2 into the storage reservoir, where they are trapped together. The impurities effectively act as a barrier to CO2 migration, enhancing storage security while eliminating environmental damage from separate impurity venting
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
Enables the storage and handling of impure liquefied CO2 without venting, maintaining a single-phase fluid flow in the pipeline and reducing environmental impact.
Implementation Method 1
compressing the withdrawn gaseous components
Implementation Method 2
the high-pressure fluid flow having the capacity for dissolving, or redissolving, therein gaseous components
Data Source
AI summary
A liquefied CO2 terminal arrangement is described rendering a liquefied CO2 terminal for carbon capture and storage (CCS) purposes connected via a high-pressure pipeline to a long-term subterranean storage reservoir capable of receiving liquefied CO2 containing impurities, especially incondensibles. Also disclosed is a CO2 terminal incorporating the arrangement, and a method of treating impurities contained in liquefied CO2 in a liquefied CO2 terminal, wherein vapour generated in a liquefied CO2 intermediate storage tank is withdrawn and injected into a high-pressure pipeline connected to a long-term subterranean storage reservoir.