Three-Stage Feed Recycle Compressor for Industrial Gas Liquefaction
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Solution Overview
Problem
Low-medium pressure liquefiers underutilize warm turbines compared to high and medium pressure liquefiers, leading to inefficient liquefaction of low boiling point gases like oxygen and nitrogen, and result in higher construction costs due to the complexity of multiple turbines and liquid expanders.
Innovation Solution
A three-stage feed recycle compressor system with a warm and cold booster, warm and cold turbines, and a heat exchanger for countercurrent indirect heat exchange, allowing for efficient compression, expansion, and heat transfer to liquefy industrial gases with reduced installation costs and full expansion without high-speed requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple turbines and liquid expanders are used in a gas liquefaction system, then liquefaction performance is improved, but device complexity and construction costs increase
Solution Approach 1:
The compression process is segmented into three distinct stages with different pressure ratios, where each stage handles a specific portion of the total compression work. This segmentation allows the system to achieve high liquefaction performance while avoiding the need for multiple complex turbine-expander units by distributing the compression function across simpler, modular compressor stages.
Solution Approach 2:
The three-stage compressor system performs multiple functions: it provides the primary compression work, enables efficient heat exchange between gas streams at different temperatures, and facilitates the liquefaction process without requiring separate dedicated turbines and liquid expanders. This multi-functionality reduces overall device complexity while maintaining productivity.
2Use of energy by moving object
If a three-stage feed recycle compressor system with warm and cold boosters is used, then compression efficiency is improved, but device complexity increases
Solution Approach 1:
Different sections of the compression system are optimized for different temperature ranges: the warm booster handles compression at higher temperatures while the cold booster operates at lower temperatures. This local optimization of compression efficiency in different thermal zones allows the system to achieve high overall efficiency without requiring an excessive number of components, as each booster is tailored to its specific operating conditions.
Solution Approach 2:
The system dynamically adjusts the operation of warm and cold boosters based on the varying temperature and pressure conditions throughout the liquefaction process. This dynamic operation allows efficient energy use across different stages of compression and expansion, achieving high compression efficiency while managing device complexity through adaptive control rather than static over-engineering.
3Use of energy by moving object
If heat exchange is performed by countercurrent flow indirect heat exchange, then heat transfer efficiency is improved, but device complexity increases
Solution Approach 1:
The heat exchange process utilizes countercurrent flow arrangement where hot and cold gas streams flow in opposite directions through the heat exchanger. This dimensional arrangement of flow paths maximizes the temperature gradient along the entire length of the heat exchanger, achieving superior heat transfer efficiency compared to parallel or cross-flow configurations, while the heat exchanger itself remains a single integrated component rather than multiple separate units.
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 improved liquefaction efficiency and reduced costs by optimizing the use of warm and cold turbines, maintaining total head pressure while rejecting more heat in the warm section, and simplifying the compressor design with fewer stages.
Implementation Method 1
The first turbo-expanded gas portion is warmed, forming a first return stream, at a heat exchanger, by countercurrent flow indirect heat exchange with the first part and the second part
Implementation Method 2
The first part and the second part are cooled in the heat exchanger
Implementation Method 3
The turbo-expanded first part is warmed, at the heat exchanger, to form a second return stream, by indirect heat exchange with the second part, assisting in liquefying the second part
Data Source
AI summary
A method and a system are provided for liquefying an industrial gas. Industrial gas is compressed, at a three-stage feed recycle compressor, to produce a first compressed gas portion and a second compressed gas portion. The second compressed gas portion is further compressed and divided into a first part and a second part. The first compressed gas portion is turbo-expanded to form a first turbo-expanded gas portion. The first turbo-expanded gas portion is warmed, at a heat exchanger, to form a first return stream. The first return stream is fed back to the three-stage feed recycle compressor, between a first compression stage and a second compression stage. A cooled first part is turbo-expanded to form a turbo-expanded first part. The turbo-expanded first part is warmed at the heat exchanger to form a second return stream. The cooled and liquefied second part is recovered as liquefied industrial gas.