Cryogenic CO/CH4 Separation Using a Single CO Pressure Cycle
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Solution Overview
Problem
Existing methods for separating carbon monoxide and nitrogen from a mixture of carbon monoxide, methane, and hydrogen face challenges due to close bubble points, leading to difficulties in achieving the required purity of carbon monoxide and efficiency in cryogenic distillation processes, particularly in maintaining optimal vaporization temperatures and pressures to prevent methane freezing.
Innovation Solution
A method utilizing a single pressure cycle for carbon monoxide vaporization, ranging from 2.6 to 35 bar, to provide refrigeration and reboiling needs across various columns, including direct injection of pure CO gas into denitrogenation columns, optimizing energy efficiency and simplifying compressor design by maintaining consistent pressures and allowing for multiple control levers for reboiling adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If CO is vaporized at atmospheric pressure to supply refrigerant to the condenser, then the CO can be vaporized at low pressure, but the vaporization temperature is too low to cool the feed gas without freezing methane
Solution Approach 1:
The patent changes the pressure parameter of CO vaporization from atmospheric pressure to a higher pressure (around 2.6 bar abs) to raise the vaporization temperature to a level that can effectively cool the feed gas without causing methane to freeze. This parameter change resolves the contradiction between achieving sufficient cooling temperature and preventing methane freezing.
2Manufacturing precision
If a denitrogenation column is installed to reduce nitrogen content in CO, then the required purity of CO can be achieved, but the process complexity and investment costs increase
Solution Approach 1:
The patent merges the denitrogenation function with the existing CO/CH4 separation column by optimizing the distillation conditions and pressure parameters. The CO-rich stream from the CO/CH4 separation column is directly used as feed to the denitrogenation column, and the nitrogen-rich overhead stream is removed. This integrated approach achieves the required CO purity while minimizing additional equipment and process complexity.
3Adaptability or versatility
If multiple pressure levels are used for CO vaporization to meet different process needs, then the refrigeration and reboiling requirements can be satisfied, but the compressor design and exchange line complexity increase
Solution Approach 1:
The patent employs a single CO compression system that operates at an optimized pressure level (around 2.6 bar abs) to fulfill multiple process functions simultaneously. The CO at this pressure level is used for vaporization in the condenser, cooling of the feed gas, and maintaining operational conditions in the separation columns. This universal pressure level eliminates the need for complex multi-pressure compressor designs and simplifies the exchange line configuration.
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 enables efficient separation by minimizing energy consumption, reducing investment costs in heat exchangers, and achieving the required purity of carbon monoxide while preventing methane freezing, thereby enhancing the overall efficiency of the separation process.
Implementation Method 1
using a single pressure for vaporization of the CO, in order to satisfy the following needs: refrigerant supply to the condenser(s) and/or cooling of the feed gas up to the inlet of the methane scrubbing column
Implementation Method 2
The invention relates to a method for separating a mixture of carbon monoxide, methane, hydrogen and optionally nitrogen by cryogenic distillation
Implementation Method 3
method for separating a mixture of carbon monoxide, methane, hydrogen and optionally nitrogen by cryogenic distillation
Implementation Method 4
This phenomenon is linked to the difficulty in separating the two components CO and N2, their bubble points being very close
Implementation Method 5
The invention furthermore consists in using a single CO cycle pressure in order to provide the needs of the reboilers of the flash column and of the CO/CH4 column
Data Source
AI summary
The invention relates to a method for separating a mixture comprising at least carbon monoxide, hydrogen, and methane. According to said method, the mixture is separated by a first separating means, at least one liquid fraction of the chamber of the separating means is sent to a product stripper, and at least part of the liquid fraction is sent from the product stripper to a CO/CH4 separating column in order to produce a methane-enriched liquid flow and a gaseous flow enriched with carbon monoxide. The process is carried out under cold conditions at least partially as a result of a carbon monoxide cycle, said cycle at least partially ensuring the condensation at the top of the CO/CH4 separating column and/or the reboiling in the chamber of the product stripper and/or the reboiling in the chamber of the CO/CH4 separating column and/or the cooling of the mixture for the first separating means.