Method and installation for cryogenic separation of a gaseous mixture by methane scrubbing
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Solution Overview
Problem
Current processes for producing hydrogen and carbon monoxide through cryogenic distillation and scrubbing require high pressure cycles, leading to inefficient energy use and the need for piston compressors due to low flow rates, which limits availability and increases energy consumption.
Innovation Solution
A process that involves cooling a gaseous mixture containing hydrogen, carbon monoxide, and methane, using a methane-rich liquid for scrubbing, and employing a centrifugal compressor with a carbon monoxide cycle that operates at reduced pressure, allowing for increased volumetric flow and reducing the energy required for separation, thereby enabling the use of centrifugal technology instead of piston technology.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a piston compressor is used to maintain low flow rate operation, then the separation process can operate at required pressure levels, but the availability decreases and energy consumption increases due to maintenance requirements
Solution Approach 1:
The patent changes the operating parameters by reducing the maximum cycle pressure from 28 bar to 22 bar and optimizing the CO cycle pressure to 6.8 bar. This parameter optimization enables the use of centrifugal compressors instead of piston compressors, improving availability while maintaining energy efficiency. The pressure parameters are carefully selected to ensure methane remains in liquid phase for scrubbing while enabling centrifugal compression technology.
2Use of energy by moving object
If the maximum cycle pressure is reduced from 28 bar to 22 bar, then energy efficiency improves and centrifugal compressor technology becomes viable, but the pressure margin for methane scrubbing becomes tighter
Solution Approach 1:
The patent optimizes multiple pressure parameters simultaneously: reducing maximum cycle pressure to 22 bar for energy efficiency, setting CO cycle pressure to 6.8 bar for centrifugal compressor operation, and maintaining scrubbing column pressure at 2.6 bar to ensure adequate pressure margin for methane liquid phase stability. This multi-parameter optimization resolves the contradiction between energy efficiency and pressure margin.
Solution Approach 2:
The patent introduces an intermediate pressure level of 6.8 bar for the CO cycle, which serves as a mediator between the high pressure required for efficient compression and the low pressure required for methane scrubbing stability. This intermediate pressure level enables centrifugal compressor operation while maintaining adequate pressure margins for the scrubbing process.
3Device complexity
If a single low pressure cycle level at 2.6 bar is used for cooling, then the CO compressor can be simplified, but a high pressure cycle of 28 bar is required to condense CO at the reboiler
Solution Approach 1:
The patent changes the pressure parameters by reducing the maximum cycle pressure from 28 bar to 22 bar and optimizing the CO cycle pressure to 6.8 bar. This enables the use of centrifugal compressors with lower complexity while maintaining the single low pressure cycle level of 2.6 bar for cooling, eliminating the need for high pressure cycles at the reboiler.
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 reduces the maximum cycle pressure from 28 bar to 22 bar, enhancing energy efficiency and allowing for the use of centrifugal compressors, which increases availability and reduces energy consumption while maintaining the necessary pressure for methane scrubbing.
Implementation Method 1
a gaseous mixture containing at least hydrogen, carbon monoxide and methane and optionally nitrogen is cooled in a heat exchanger
Implementation Method 2
a methane-rich liquid is introduced into the scrubbing column as scrubbing liquid
Implementation Method 3
employing a centrifugal compressor with a carbon monoxide cycle that operates at reduced pressure, allowing for increased volumetric flow
Data Source
AI summary
In a process for the combined production of a) a hydrogen-enriched gas and a carbon monoxide-enriched gas and/or b) a mixture of hydrogen and carbon monoxide by cryogenic distillation and scrubbing, a still liquor is extracted from a scrubbing column and sent to a stripping column, a still liquor is extracted from the stripping column and sent to a separating column for carbon monoxide and methane and a cooling fluid is used at a pressure greater than that of the head of the separating column for cooling at least one fluid extracted at an intermediate level from the scrubbing column.