Method and apparatus for separating a mixture of hydrogen and carbon dioxide
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for separating hydrogen and carbon dioxide from mixtures, particularly those derived from hydrogen production processes, face inefficiencies and instability due to reliance on turbines and complex control loops, leading to reduced performance and reliability.
Innovation Solution
A method involving partial condensation and membrane separation, combined with turbine expansion of residues, where the residue is expanded without reheating, and the gas is cooled indirectly, stabilizing the system by regulating temperature variations and reducing the need for external heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a turbine is used to expand residue and recover pressure energy, then energy efficiency is improved, but system complexity and control loop requirements increase
Solution Approach 1:
The patent extracts the turbine component from the system entirely, replacing it with a direct compression approach where the residue stream is compressed without passing through a turbine expansion stage. This eliminates the complex control loops required for turbine operation while maintaining energy efficiency through direct compression of the permeate stream.
Solution Approach 2:
The system uses the cold residue stream from the membrane unit to directly cool the feed gas in the heat exchanger, creating a self-sustaining thermal balance. This self-service cooling approach eliminates the need for external cooling systems and complex control mechanisms, while the compression work directly provides the necessary pressure energy.
2Temperature
If external heating is applied to maintain temperature in the heat exchanger, then temperature stability is improved, but energy consumption and system complexity increase
Solution Approach 1:
The system uses the cold residue stream from the membrane separation unit to directly cool the feed gas in the heat exchanger, creating a self-sustaining thermal balance. The temperature stability is maintained through this internal heat exchange mechanism without requiring external heating or cooling systems, thereby reducing energy consumption and system complexity.
Solution Approach 2:
The patent changes the temperature parameter of the residue stream by using it in its cold state directly from the membrane unit, rather than heating it before heat exchange. This parameter change allows the residue to function as an effective cooling medium, maintaining temperature stability through the natural temperature differential between the cold residue and the feed gas.
3Temperature
If the residue is reheated before being sent to the turbine, then temperature stability is improved, but energy consumption increases
Solution Approach 1:
The patent removes the reheating step from the process flow. The residue stream is taken directly from the membrane unit at its cold temperature and sent to the heat exchanger without any intermediate heating, thereby eliminating the energy loss associated with reheating while maintaining sufficient temperature stability for the cooling function.
Solution Approach 2:
The patent converts the previously harmful cold residue stream (which required energy-intensive reheating) into a beneficial cooling resource. By using the cold residue directly to cool the feed gas in the heat exchanger, the system transforms what was previously a waste stream requiring energy input into a free cooling source, thereby reducing overall energy consumption.
4Productivity
If multiple separation stages with intermediate heating are used, then separation efficiency is improved, but device complexity and energy consumption increase
Solution Approach 1:
The patent merges the separation and cooling functions into a single integrated process. The membrane separation unit operates continuously with the residue stream directly feeding the heat exchanger, eliminating the need for multiple discrete separation stages with intermediate heating steps. This integration maintains high separation efficiency while reducing device complexity and energy consumption.
Solution Approach 2:
The system maintains continuous operation of the membrane separation unit with the residue stream continuously flowing to the heat exchanger. This continuous action eliminates the need for intermittent heating and multiple staging, thereby maintaining high separation efficiency with simpler equipment and lower energy consumption through uninterrupted process flow.
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 enhances separation efficiency and stability by eliminating the need for external heating, reducing exchanger surface area, and improving system robustness, while maintaining performance and reliability.
Implementation Method 1
Cooling the mixture from a first temperature in a heat exchanger by sending the mixture to the heat exchanger, resulting in the partial condensation of the mixture into a liquid phase enriched in carbon dioxide and a gaseous phase depleted in carbon dioxide
Implementation Method 2
partial condensation of the mixture into a liquid phase enriched in carbon dioxide
Implementation Method 3
membrane separation unit generating one or more permeates enriched in hydrogen and/or carbon dioxide and depleted in at least one compound lighter than carbon dioxide
Implementation Method 4
expanding the at least one residue from a first pressure in one or more turbines producing an expanded fluid to a second pressure lower than the first pressure and to a third temperature lower than the first temperature
Implementation Method 5
the fluid at the second pressure produced during step e) constituting the gaseous fluid of step a) which heats up in the heat exchanger by indirect heat exchange with the mixture
Data Source
Figure 1
AI summary
In a process for separating a mixture containing hydrogen and carbon dioxide, the following steps are present: a) Cooling the mixture (1) in a heat exchanger (7) by sending the mixture to the heat exchanger, resulting in partial condensation of the mixture into a liquid phase enriched in carbon dioxide (3) and a gaseous phase depleted in carbon dioxide (5); b) Separation of the liquid phase (3) from the gaseous phase (5) in a separator pot (S); c) Heating of the gaseous phase (5) from at least one of the separator pots in the heat exchanger; d) Sending at least one heated portion (9) from step c) to a membrane separation unit (M), generating a residue (11) depleted in hydrogen and carbon dioxide; e) Expansion of at least one residue in a turbine (T) producing an expanded fluid (13); f) Heating of the expanded fluid in the heat exchanger. by indirect heat exchange.