Cold Vapor Separator Layout for Lower-Power Mixed Refrigeration
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Solution Overview
Problem
Current mixed refrigerant systems for cooling and liquefying natural gas are complex, inefficient, and consume excessive power due to difficulties in finding a single refrigerant composition that approximates the natural gas cooling curve and the need to cool all components to the lowest temperature, leading to thermodynamic inefficiencies and increased mechanical complexity.
Innovation Solution
A multi-stream heat exchanger system that separates high-pressure mixed refrigerant streams into vapor and liquid streams, uses a cold vapor separator to form a cold temperature refrigerant stream, and combines it with a middle temperature refrigerant stream to efficiently cool the gas, reducing power consumption by optimizing the refrigeration process and minimizing thermodynamic losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single mixed refrigerant composition is used to cool natural gas, then the system complexity is reduced, but it is difficult to find a composition that closely approximates the natural gas cooling curve
Solution Approach 1:
The refrigerant system is segmented into multiple streams with different temperature ranges. A first mixed refrigerant stream handles the warmer temperature range while a second mixed refrigerant stream handles the colder temperature range, allowing each stream to be optimized for its specific temperature range and collectively approximate the natural gas cooling curve more accurately
Solution Approach 2:
Different refrigerant compositions are used in different parts of the system. The first mixed refrigerant has a composition optimized for warmer temperatures while the second mixed refrigerant has a composition optimized for colder temperatures, allowing each region to have the appropriate refrigerant properties for its operating conditions
2Stability of the object's composition
If all refrigerant components are cooled to the lowest temperature, then complete liquefaction is achieved, but thermodynamic efficiency decreases and power consumption increases
Solution Approach 1:
The refrigerant streams are segmented by temperature range, with the first mixed refrigerant stream operating in the warmer temperature range and the second mixed refrigerant stream operating in the colder temperature range. This segmentation allows lighter components to be recovered at higher temperatures before the final cooling stage, reducing the energy required to cool all components to the lowest temperature
Solution Approach 2:
The system performs preliminary separation and recovery of lighter refrigerant components at intermediate temperature stages before the final cooling to lowest temperature. This preliminary action removes components that would otherwise require excessive energy to cool to the lowest temperature, thereby reducing overall power consumption while maintaining complete liquefaction
3Loss of energy
If multiple refrigeration levels are used to approximate the cooling curve, then cooling efficiency improves, but mechanical complexity increases due to additional compressor trains
Solution Approach 1:
Multiple refrigerant streams at different temperature ranges are merged into a unified system that operates with fewer compressor trains. The first and second mixed refrigerant streams are integrated to work together, achieving the benefits of multiple refrigeration levels while reducing mechanical complexity through consolidated compression infrastructure
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 significantly reduces power consumption and mechanical complexity by efficiently cooling natural gas, achieving closer approximation of the natural gas cooling curve and improving thermodynamic efficiency through optimized refrigerant stream management and separation.
Implementation Method 1
a feed fluid cooling passage having an inlet configured to receive a feed fluid stream and an outlet through which a cooled fluid stream exits the feed fluid cooling passage
Implementation Method 2
A cold vapor separator is configured to receive fluid from the high pressure vapor passage of the heat exchanger
Implementation Method 3
A cold vapor expansion device is configured to receive fluid from the cold separator vapor passage of the heat exchanger
Data Source
AI summary
Provided are mixed refrigerant systems and methods and, more particularly, to a mixed refrigerant system and methods that provides greater efficiency and reduced power consumption via control of a liquid level in a cold vapor separator device.