Installation for separation and liquefaction of methane and co2 comprising a vapour condenser placed in an intermediate stage of the distillation column
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Solution Overview
Problem
Current biogas purification processes are inefficient in separating and liquefying methane and carbon dioxide with minimal methane loss and operational complexity, particularly due to high CO2 content and the need for additional modules for liquefaction.
Innovation Solution
A combined installation and process incorporating a distillation column with a recycle gas system, exchangers for cooling and liquefaction, and thermal integration to recover cold energy, allowing for simultaneous separation and liquefaction of methane and carbon dioxide with reduced energy usage and methane loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If absorption, permeation, or adsorption techniques are used for biogas purification, then methane can be obtained, but additional modules are required for liquefaction and CO2 content remains too high
Solution Approach 1:
The patent combines the purification and liquefaction functions into a single integrated cryogenic distillation system. The distillation column simultaneously separates methane from CO2 and enables liquefaction of purified methane, eliminating the need for separate purification and liquefaction modules that would be required with absorption or adsorption techniques.
Solution Approach 2:
The cryogenic distillation system performs multiple functions within a single apparatus: it purifies biogas by separating CO2 from methane, condenses methane to liquid form, and manages CO2 removal. This multi-functional approach reduces the number of required modules compared to sequential purification techniques.
2Quantity of substance
If cryo-trapping system is used for CO2 solidification, then separation is achieved, but cold energy cannot be recovered and multiple exchangers are needed
Solution Approach 1:
The patent recovers the cold energy that would otherwise be discarded in cryo-trapping systems. The distillation column operates at cryogenic temperatures, and the cold energy is utilized for methane condensation and overall process cooling, transforming a energy loss into a useful resource.
Solution Approach 2:
The patent merges the CO2 separation function with the methane condensation function in a single distillation column. The cold energy from CO2 solidification is integrated into the methane liquefaction process, eliminating the need for separate exchangers and improving energy efficiency.
3Ease of operation
If distillation column operates without intermediate condensation, then simple operation is maintained, but methane loss increases and energy efficiency decreases
Solution Approach 1:
The distillation column is segmented into multiple stages with an intermediate condenser positioned at a specific tray. This segmentation allows for controlled partial condensation of methane vapor, improving separation efficiency and reducing methane loss while maintaining manageable operational complexity through structured zone differentiation.
Solution Approach 2:
The intermediate condenser performs preliminary condensation of methane vapor before the final condensation stage. This preliminary action allows for better control of methane recovery and reduces losses by condensing methane at an intermediate point where temperature and pressure conditions are optimized for efficient separation.
4Quantity of substance
If separate purification and liquefaction systems are used, then each process can be optimized, but operational complexity and cost increase
Solution Approach 1:
The patent merges purification and liquefaction operations into a single cryogenic distillation column. The column simultaneously achieves CO2 removal, methane purification, and methane condensation, reducing operational complexity and infrastructure requirements compared to separate systems while maintaining high purification efficiency.
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 efficient separation and liquefaction of biogas components in a single operation, minimizing methane loss and operational complexity while recovering energy used in the liquefaction process, thus enhancing the economic viability of biogas utilization.
Implementation Method 1
A distillation column K01 fed by the cooled mixture and for producing methane at the top of the column and a liquid enriched in CO2 at the bottom of the column
Implementation Method 2
An exchanger E01 for cooling the compressed mixture
Implementation Method 3
An exchanger E02 for liquefying the methane produced at the top of the column
Implementation Method 4
A means M3 for expanding and heating the liquid enriched in CO2 recovered at the bottom of the column and recovering the cold from the liquid enriched in CO2
Data Source
Figure 1
AI summary
Combined cryogenic separation and liquefaction installation for methane and carbon dioxide contained in a biogas stream, comprising: - A means M1 for mixing biogas 1 with a recycled gas R, - A compressor for compressing the mixture to distillation pressure, - A heat exchanger E01 for cooling the compressed mixture, - A distillation column K01 fed by the cooled mixture and producing methane at the top of the column and a CO2-enriched liquid at the bottom of the column, - A vaporizer/condenser located in an intermediate stage of the distillation column K01, - A heat exchanger E02 for liquefying the methane produced at the top of the column, - A means M2 for separating the liquefied methane into two parts: a "reflux" part 3 and a "product" part 2, - A means M3 for expanding and heating the CO2-enriched liquid recovered at the bottom of the column and for recovering the cold from the CO2-enriched liquid.and - A separator pot V01 allowing the CO2-enriched stream from the medium M3 to be received and the overhead vapor recovered from liquid CO2 4, With - the medium M1 such that the recycled gas R corresponds to the overhead vapor recovered at the outlet of the separator pot V01, and - the exchanger E01 and the medium M3 being considered as one.