MIEC Membrane Oxygen Plant Vacuum Heat Recovery
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Solution Overview
Problem
Conventional oxygen production methods, such as pressure swing adsorption and cryogenic air separation, have high specific energy consumption, making decentralized oxygen generation economically unviable, especially for small-scale applications, and existing membrane separation processes using mixed conductive ceramic membranes are inefficient due to high thermal and compression energy requirements.
Innovation Solution
A membrane system with a housing containing MIEC membranes, a vacuum pump, and regenerative heat exchangers, where the housing is not pressure-tight, allowing for air flow reversal and utilizing waste heat for heating, with oxygen extraction by vacuum operation, optimizing energy efficiency by minimizing compression energy and utilizing waste heat for heating fresh air.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If MIEC membrane separation process is used for oxygen production, then oxygen separation selectivity is improved, but specific energy consumption increases due to high thermal and compression energy requirements
Solution Approach 1:
The patent changes the operational parameters by using vacuum operation instead of compression, and implements regenerative heating to preheat feed air using waste heat from the permeate stream. This transforms the energy input method while maintaining the high-temperature operation necessary for MIEC membrane function, thereby reducing compression energy requirements and improving overall energy efficiency
Solution Approach 2:
The patent converts the waste heat from the hot permeate stream into a useful resource by using it to preheat the feed air through a heat exchanger. This regenerative approach transforms what would otherwise be wasted thermal energy into a beneficial preheating function, reducing the additional energy required to maintain membrane operating temperature
2Productivity
If air compression is used to generate driving force for oxygen transport, then oxygen flux through membrane is improved, but compression energy requirement increases
Solution Approach 1:
Instead of compressing the feed air to create the driving force for oxygen transport, the patent inverts the approach by using vacuum operation on the permeate side. This creates a pressure differential that drives oxygen through the membrane without requiring energy-intensive compression of the feed stream, thereby maintaining productivity while reducing compression energy requirements
3Productivity
If high temperature operation (800-900°C) is maintained for MIEC membrane function, then oxygen permeation is improved, but thermal energy requirement increases
Solution Approach 1:
The patent implements preliminary heating of the feed air using waste heat from the permeate stream before the air enters the membrane module. This regenerative preheating action reduces the additional thermal energy required to bring the feed air up to the membrane's optimal operating temperature range, thereby reducing overall thermal energy requirements while maintaining high oxygen permeation
4Adaptability or versatility
If decentralized oxygen generation is implemented, then local oxygen supply is improved, but economic viability deteriorates due to high energy consumption
Solution Approach 1:
The patent changes the energy input parameters by replacing compression with vacuum operation and implementing regenerative heating. These parameter changes significantly reduce the specific energy consumption of decentralized MIEC membrane systems, making them economically viable for local oxygen generation applications while maintaining the advantage of distributed, on-demand oxygen supply
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
The system achieves a significant reduction in specific energy consumption, with a total energy requirement comparable to or lower than decentralized PSA systems, and allows for efficient operation across a wide range of oxygen separation degrees, reducing investment costs and energy losses.
Implementation Method 1
The transport of oxygen is based on the transport of oxide ions through the gas-tight ceramic material and the parallel transport of electronic charge carriers (electrons or defect electrons)
Implementation Method 2
The transport of oxygen is based on the transport of oxide ions through the gas-tight ceramic material and the parallel transport of electronic charge carriers (electrons or defect electrons)
Implementation Method 3
at least 85% of the thermal energy required to heat the fresh air is used by using the waste heat from the exhaust air and/or the oxygen obtained
Implementation Method 4
the oxygen can be obtained by suction with a vacuum. The vacuum process requires less compression energy
Data Source
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AI summary
The invention relates to a membrane separation process and to a membrane plant for energy-efficient oxygen production using ceramic membranes of mixed conductivity. The problem addressed by the invention is that of specifying a method wherein the disadvantages of the prior art are avoided and the energy efficiency of the MIEC membrane process for oxygen production, especially with autonomous MIEC membrane plants, is significantly enhanced. According to the invention, the problem is solved by a membrane separation process for energy-efficient recovery of oxygen from heated fresh air using membranes of mixed conductivity in vacuum operation, the fresh air being discharged as waste air after removal of the oxygen, in that at least 85% of the thermal energy required to heat the fresh air is effected by utilizing the waste heat in the waste air and/or in the oxygen recovered, in that the residual heating of the fresh air is achieved by external energy supply, and in that the ratio of fresh air to oxygen produced in normal operation is set within the ranges of 6:1 and 25:1.