CO₂ Separation with Phase Separator to Reduce Boil-Off Gas Losses
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Solution Overview
Problem
Current CO2 separation plants face inefficiencies in handling boil-off gases (BOG) generated during storage and loading operations, leading to CO2 losses as these gases are often vented instead of being recycled or liquefied, particularly in small-scale plants where they are used for adsorbent regeneration and released into the atmosphere.
Innovation Solution
A method and apparatus that recycle evaporated gases from storage and loading systems through a combination of distillation and phase separation, utilizing a heat exchanger and distillation column to separate CO2 from lighter impurities, with a phase separator to optimize fluid circulation and reduce coolant demand, allowing for the purification and reuse of CO2.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If boil-off gases are vented to atmosphere or used for adsorbent regeneration, then CO2 losses occur, but the system operates with simpler handling procedures
Solution Approach 1:
The patent converts the harmful waste stream (boil-off gas containing CO2 losses) into a beneficial resource by recycling it through distillation and phase separation processes. The CO2-rich gas is liquefied and returned to storage, transforming what was previously a loss into a recovery opportunity that reduces CO2 emissions and improves overall system efficiency.
Solution Approach 2:
Instead of discarding the boil-off gas to atmosphere or using it solely for adsorbent regeneration, the system recovers the CO2 by implementing a distillation column and phase separator. The process separates CO2 from lighter impurities, liquefies the purified CO2, and returns it to storage, thereby recovering valuable CO2 that would otherwise be lost.
2Productivity
If evaporated gases are recycled to separation unit, then CO2 purification efficiency increases, but coolant demand increases
Solution Approach 1:
The patent utilizes phase transitions (vaporization and condensation) in the distillation column and phase separator to separate CO2 from lighter impurities. By controlling temperature and pressure during these phase changes, the system achieves efficient CO2 purification while managing coolant requirements through the inherent thermal dynamics of the phase transition process.
Solution Approach 2:
The system changes physical parameters (temperature, pressure) throughout the process to optimize both purification efficiency and energy consumption. The distillation column operates at specific temperature gradients to achieve separation, while the phase separator uses pressure differential to facilitate phase separation, thereby balancing productivity with coolant demand.
3Manufacturing precision
If distillation column with heat and mass transfer means is used, then separation efficiency improves, but device complexity increases
Solution Approach 1:
The separation system is segmented into distinct functional units: a distillation column for primary separation, a phase separator for phase division, and associated heat exchangers. This segmentation allows each component to perform its specific function efficiently while maintaining overall system manageability and modular complexity.
Solution Approach 2:
The phase separator acts as an intermediary device between the distillation column and the storage system. It receives the two-phase output from distillation, separates the phases, and directs them to appropriate destinations, thereby simplifying the overall flow and reducing the complexity burden of the distillation column itself.
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 effectively recycles and purifies CO2-rich gases, reducing losses and increasing the efficiency of CO2 separation processes by optimizing fluid circulation and coolant usage, enabling the production of high-purity CO2 for storage and reuse.
Implementation Method 1
a second gas mixture containing carbon dioxide and at least one impurity lighter than carbon dioxide is separated in a separation system comprising a heat exchanger and at least one distillation column
Implementation Method 2
the second gas mixture and a first gas mixture containing carbon dioxide and at least one impurity lighter than carbon dioxide are separated in a separation system comprising a heat exchanger and at least one distillation column to form a liquid stream purer in carbon dioxide than the second gas mixture and a gas less pure in carbon dioxide than the first gas mixture
Implementation Method 3
a second part of the liquid flow is partially vaporized to form a two-phase flow and the two-phase flow is separated to form a gas and a liquid in the phase separator
Implementation Method 4
a gas is formed by mixing the vaporized liquid and the reheated gas and is compressed in a compressor with at least a part of the second mixture
Data Source
Figure 1
AI summary
In a process for separating a first gaseous mixture (05) containing carbon dioxide and at least one impurity lighter than carbon dioxide, the first gaseous mixture originates from a liquid carbon dioxide storage (70), a second gaseous mixture (11, 12) containing carbon dioxide and at least one impurity lighter than carbon dioxide is separated in a separation system comprising a heat exchanger (20) and a distillation column (40) to form a liquid flow purer in carbon dioxide than the second gaseous mixture, the second gaseous mixture is cooled in the heat exchanger upstream of the separation, the liquid flow is withdrawn from a distillation column of the separation system, a first part (33) of the liquid flow is sent to a liquid carbon dioxide storage (70), a second part (03) of the liquid flow is sent to a phase separator (50) with the first gaseous mixture,Fluids from the phase separator are heated, compressed (10) and sent to distillation.