Cryogenic Air Separation Without Inter-Cooling for Oxy-Fuel Power
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Solution Overview
Problem
Current cryogenic air separation systems for producing high-pressure oxygen are energy-intensive due to the need for large amounts of shaft power to drive compressors and refrigeration, and they often require additional cooling to prevent freezing of minor air components, which increases operational costs and complexity.
Innovation Solution
A cryogenic air separation system that operates without inter-cooling between compressor stages, using adiabatic compression to achieve high pressures and transfer the adiabatic heat of compression to a working fluid, such as a CO2 stream, which can be used in power production processes, thereby reducing energy consumption and integrating efficiently with oxy-fuel combustion systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If inter-cooling is used between compressor stages, then the air temperature is reduced and compression stability is improved, but energy consumption increases due to additional cooling requirements
Solution Approach 1:
The patent extracts the inter-cooling step from the compression process, eliminating the cooling equipment and associated energy consumption while maintaining compression stability through adiabatic compression design
Solution Approach 2:
The patent converts the harmful effect of heat generation during compression into a beneficial resource by utilizing the adiabatic heat for pre-heating the oxygen product and for driving the refrigeration cycle, thereby reducing external energy requirements
2Manufacturing precision
If additional cooling systems are implemented to prevent freezing of minor air components, then product purity is improved, but device complexity and operational costs increase
Solution Approach 1:
The patent merges the freezing prevention function with the existing heat exchanger and refrigeration cycle, using the adiabatic heat to preheat oxygen which then provides cooling capacity to prevent freezing of minor components, eliminating the need for separate cooling systems
Solution Approach 2:
The system uses its own adiabatic compression heat to provide the cooling necessary to prevent freezing of minor air components, making the system self-sufficient and reducing external equipment requirements
3Manufacturing precision
If traditional cryogenic distillation is used with refrigeration cycles, then high purity oxygen is produced, but large amounts of shaft power are required for compressors and refrigeration
Solution Approach 1:
The patent converts the waste heat from adiabatic compression into a useful resource that drives the refrigeration cycle and pre-heats the oxygen product, thereby reducing the shaft power required for compression and refrigeration
Solution Approach 2:
The patent changes the compression process from isothermal (with inter-cooling) to adiabatic (without inter-cooling), fundamentally altering the thermal parameters and enabling heat recovery that reduces overall power consumption
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 production of high-pressure oxygen with 90% to 99.5% molar purity at pressures up to 500 bar while minimizing energy usage and integrating seamlessly with power production processes, enhancing overall efficiency and reducing the need for secondary cooling systems.
Implementation Method 1
using adiabatic compression to achieve high pressures and transfer the adiabatic heat of compression to a working fluid, such as a CO2 stream
Implementation Method 2
transfer the adiabatic heat of compression to a working fluid, such as a CO2 stream
Implementation Method 3
separating air to provide a purified stream of one or more individual components thereof
Implementation Method 4
The formation of liquid air in the cryogenic equipment typically requires some refrigeration. Such liquid may be formed by Joule Thomson expansion of air across a valve or through an expander
Data Source
AI summary
The present invention relates to a cryogenic air separation process that provides high pressure oxygen for an oxy-fired combustion of a fuel (e.g., a carbonaceous fuel). The air separation process can be directly integrated into a closed cycle power production process utilizing a working fluid, such as CO2. Beneficially, the air separation process can eliminate the need for inter-cooling between air compression stages and rather provide for recycling the adiabatic heat of compression into a process step in a further methods wherein an additional heat supply is beneficial.