Ethane-CO2 Flash Separation Using Solid CO2 Formation
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Solution Overview
Problem
Current methods for separating carbon dioxide (CO2) and ethane from mixed streams are inefficient, as they either contaminate ethane, require large amounts of energy, or result in incomplete recovery due to the formation of azeotropes, which hinder separation by conventional fractionation techniques.
Innovation Solution
A method involving the generation of a liquid stream of CO2 and ethane, which is then flashed through a valve into an accumulation vessel, allowing solid CO2 to form and be accumulated while enriching the vapor stream in ethane, enabling subsequent distillation for partial ethane recovery and subsequent recycling to achieve complete separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional fractionation is used to separate CO2 from ethane, then separation is attempted, but the azeotropic mixture prevents complete separation
Solution Approach 1:
The patent changes the physical state parameter of CO2 from liquid/gas phase to solid phase by controlling temperature and pressure conditions. This phase change allows separation of CO2 from ethane by forming solid CO2 that can be mechanically removed, bypassing the azeotropic limitation of conventional fractionation
Solution Approach 2:
The invention utilizes the phase transition of CO2 to solid form through controlled cooling and pressure conditions. The solid CO2 is then separated from the liquid ethane phase, achieving complete separation that conventional vapor-liquid fractionation cannot accomplish due to the azeotropic mixture
2Manufacturing precision
If extractive distillation with heavy component is used, then ethane absorption is improved, but process complexity and energy consumption increase
Solution Approach 1:
The patent extracts CO2 from the mixture by forming solid CO2 that can be physically removed from the liquid ethane phase. This direct extraction method eliminates the need for complex extractive distillation systems with heavy components, reducing process complexity while achieving complete ethane recovery
Solution Approach 2:
The invention uses temperature and pressure control as intermediaries to induce solid CO2 formation. This intermediary approach allows separation without requiring additional chemical agents or complex extraction systems, simplifying the overall process
3Manufacturing precision
If two-pressure fractionation is used, then CO2 and ethane separation is attempted, but large recycle streams and energy consumption are required
Solution Approach 1:
The patent changes the separation mechanism from pressure-based fractionation to temperature-based phase transition. By controlling temperature to form solid CO2, the process achieves separation without requiring large recycle streams or high energy consumption associated with two-pressure fractionation systems
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 allows for the substantial separation of CO2 and ethane with minimal residual contamination and hydrocarbon loss, producing a pressurized liquid CO2 stream for disposal and a clean vapor ethane stream for sale, while integrating heat demands and cooling sources to reduce external refrigeration needs.
Implementation Method 1
passing the liquid stream through a flash valve into an accumulation vessel, forming a gas that is enhanced in ethane, and forming solid CO2
Implementation Method 2
a flash valve configured to isoenthalpically flash the mixed stream forming solid CO2 and a vapor stream enhanced in ethane
Data Source
AI summary
Embodiments described herein provide methods and systems for separating a mixed ethane and CO2. A method described includes generating a liquid stream including ethane and CO2. The liquid stream is flashed to form an ethane vapor stream and solid CO2. The solid CO2 is accumulated in an accumulation vessel and the gas is removed from the top of the accumulation vessel.