Method for operating a reliquefaction system
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Solution Overview
Problem
Existing cryogenic fluid reliquefaction systems face challenges in reliability and availability due to inefficiencies in thermal exchange processes and pressure control, leading to nitrogen vapor loss and energy waste.
Innovation Solution
A reliquefaction system with multiple sub-coolers, variable speed systems, and pressure controllers is implemented, allowing for efficient thermal exchange and pressure management through lead-lag arrangements and shared variable speed systems across motors and compressors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single motor and compressor are used in the reliquefaction system, then the device complexity is reduced, but the reliability decreases due to single point of failure
Solution Approach 1:
The reliquefaction system is divided into multiple independent sub-coolers (at least two), each with its own motor and compressor. This segmentation allows the system to continue operating with reduced capacity if one sub-cooler fails, thereby improving reliability without requiring a complete system redesign.
Solution Approach 2:
Multiple sub-coolers are merged into a single integrated reliquefaction system that shares common infrastructure such as the cryogenic tank, recirculation loop, and control systems. This merging approach improves reliability through redundancy while limiting the increase in overall system complexity by reusing existing components.
2Ease of operation
If variable speed systems are dedicated to each motor and compressor, then the ease of operation is improved, but the device complexity increases
Solution Approach 1:
The variable speed control system is designed as a universal, shareable resource that can be dynamically allocated to different motors and compressors as needed. This multi-functional approach allows a single variable speed system to serve multiple sub-coolers, improving ease of operation while avoiding the complexity of having dedicated variable speed systems for each component.
Solution Approach 2:
The system implements dynamic allocation of the variable speed system among multiple sub-coolers based on operational requirements. This dynamic approach allows the control system to adapt to changing conditions and maintain ease of operation without requiring static, dedicated control systems for each component, thereby limiting complexity increase.
3Loss of energy
If indirect thermal exchange is used for enthalpy extraction, then the manufacturing precision is improved, but the loss of energy increases due to multiple compression and cooling steps
Solution Approach 1:
The system converts the waste heat from sub-cooled liquid cryogenic fluid into a useful resource by using it for indirect thermal exchange to recondense vapor. This approach transforms what would otherwise be wasted energy into a beneficial cooling source, reducing overall energy loss while maintaining effective thermal exchange through controlled heat transfer processes.
Solution Approach 2:
The system utilizes phase transitions of the cryogenic fluid (liquid to vapor and back to liquid) as the core mechanism for thermal exchange. By leveraging the latent heat of vaporization and condensation, the system achieves efficient heat transfer that reduces energy loss while maintaining the precision needed for reliable reliquefaction operation.
4Reliability
If multiple main cryogenic tanks are used, then the reliability is improved, but the device complexity increases due to additional pressure controllers and valves
Solution Approach 1:
The cryogenic storage system is segmented into multiple independent tanks, each capable of operating autonomously. This segmentation improves reliability by providing redundancy - if one tank becomes unavailable, the system can continue operating with the remaining tanks. The complexity increase is managed by using standardized, modular pressure control components for each tank.
Solution Approach 2:
The system manages the complexity of multiple tanks by standardizing key parameters such as pressure control ranges, valve specifications, and controller settings across all tanks. This parameter standardization allows for easier operation and maintenance despite the increased number of components, effectively limiting the practical impact of the complexity increase while maintaining reliability benefits.
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
Enhances the reliability and availability of cryogenic fluid reliquefaction by optimizing thermal exchange and pressure control, reducing nitrogen vapor loss and energy waste.
Implementation Method 1
mix the gaseous stream with a subcooled liquid so that the direct thermal exchange between the gas and subcooled liquid will condense the gaseous stream
Implementation Method 2
the direct thermal exchange between the gas and subcooled liquid will condense the gaseous stream
Implementation Method 3
at least one variable speed system to control the speed of at least one motor
Implementation Method 4
the pressure in the two different main cryogenic tanks are controlled with pressure controllers acting on two different subcooled liquid cryogenic fluid valves
Data Source
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AI summary
A method for increasing the reliability and availability of a cryogenic fluid reliquefaction system is provided. It may comprise at least N sub-coolers comprising a motor and a compressor and at least one variable speed. It may comprise N-1 variable speed systems to be shared between the motors and compressors if N equals 2, or N-2 variable speed systems to be shared between the motors and compressors if N is greater than 2. If may comprise two different liquid cryogenic fluid users are provided liquid cryogenic fluid, utilizing two different main cryogenic tanks, with a common sub-cooler and recirculation loop, wherein the pressure in the two different main cryogenic tanks are controlled with pressure controllers acting on two different subcooled liquid cryogenic fluid valves. And or, it may comprise at least one liquid cryogenic fluid user is provided refrigeration from two or more sub-cooling systems in a lead-lag arrangement.