Thermal Compression of Oxygen Using Mixed Conducting Ceramic Membranes
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Solution Overview
Problem
Existing methods for generating compressed oxygen from air require mechanical or electromechanical compression, which are costly and pose safety risks, and using steam as a purge gas leads to equilibrium and reduced oxygen partial pressure, making it difficult to achieve superatmospheric pressure without mechanical compression.
Innovation Solution
The method involves passing water in various states through a circuit to generate high oxygen pressure separately from the membrane module, using steam as a purge gas without mechanical compression, and employing a nonreturn valve to prevent oxygen return, allowing thermal compression of oxygen to pressures above ambient using a mixed-conduction ceramic membrane with steam, and utilizing a BSCF membrane tube and introduction tube configuration to achieve efficient oxygen separation and compression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If steam is used as purge gas in MIEC membrane plants, then oxygen separation is achieved, but oxygen partial pressure equilibrium is reached and driving force is reduced
Solution Approach 1:
The patent changes the temperature parameter of the steam to maintain a temperature gradient across the membrane. By heating the steam to high temperatures (e.g., 800-1000°C) before it contacts the membrane, the oxygen partial pressure difference is maintained despite using steam as purge gas, thus preserving the driving force for oxygen transport.
Solution Approach 2:
The patent divides the system into distinct temperature zones: a hot zone where steam is generated and contacts the membrane, and a cooler zone where the permeate is collected. This segmentation prevents equilibrium by maintaining different temperatures and thus different oxygen partial pressures in different regions of the system.
2Stress or pressure
If mechanical compression is used to achieve superatmospheric oxygen pressure, then oxygen is available for downstream processes, but capital costs and safety risks increase
Solution Approach 1:
The patent replaces mechanical compression systems with a thermal process. By using high-temperature steam as the purge gas and maintaining a temperature gradient across the membrane, the system achieves both oxygen separation and pressure increase without mechanical compressors, thereby eliminating the associated safety risks and capital costs.
Solution Approach 2:
The patent utilizes the phase transition of water to steam and back to generate the necessary pressure differential. Water is evaporated to high-temperature steam on the feed side, creating high pressure, and then condensed on the permeate side, maintaining low pressure. This phase transition cycle drives oxygen transport and achieves superatmospheric pressure without mechanical compression.
3Productivity
If air compression is used before membrane separation, then oxygen generation is efficient, but additional energy consumption and equipment complexity arise
Solution Approach 1:
The patent merges the compression function with the thermal field by using high-temperature steam as both the heating medium and the pressure-generating purge gas. This eliminates the need for separate compression equipment and integrates multiple functions (heating, pressurizing, and purging) into a single thermal process.
Solution Approach 2:
The steam serves multiple functions simultaneously: it acts as the purge gas for oxygen separation, provides the thermal energy for driving oxygen transport through the membrane, and generates the pressure differential needed for superatmospheric oxygen output. This multi-functionality reduces equipment complexity while maintaining productivity.
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 the generation of pure, compressed oxygen at superatmospheric pressures without mechanical compression, allowing for electrical energy generation through steam turbines and efficient thermal compression, overcoming the limitations of previous methods by maintaining a driving force for oxygen transport and preventing equilibrium.
Implementation Method 1
Oxygen transport is based on the transport of oxide ions through the gastight ceramic material
Implementation Method 2
on the parallel transport of electronic charge carriers (electrons or defect electrons)
Implementation Method 3
The permeation of oxygen through an MIEC membrane can be described by the Wagner equation and is determined in particular by the ambipolar conductivity of the material at service temperature
Implementation Method 4
passing water in various aggregate states through a circuit
Implementation Method 5
The water is passed in the circuit
Data Source
AI summary
The invention relates to a method and an arrangement for the continuous production of compressed oxygen from air using mixed conducting ceramic membranes. The aim of the invention is to provide a way of isolating pure oxygen from the air and compressing said oxygen to pressures above the ambient pressure, without using mechanical or electromechanical compression of air or oxygen. To achieve this aim, according to the invention water in various aggregate states is conducted in a circuit and the configuration of the equipment is designed such that the desired high oxygen pressure is produced in a separate area from the membrane module and the oxygen produced is prevented from mixing with the freshly produced water vapour.