Multi-Compressor Cryogenic Air Separation Using Asynchronous Motors
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Solution Overview
Problem
Existing air separation technologies face challenges in scalability, energy efficiency, and reliability, particularly beyond standard capacities, where high-pressure compressors become complex and costly, and synchronous motors are limited beyond 25 MW, necessitating a more flexible and cost-effective solution for cryogenic distillation.
Innovation Solution
The use of multiple small high-pressure compressors driven by asynchronous motors, each connected to a single purification unit and cold box, eliminating the need for air boosters driven by motors or steam turbines, allowing for flexible throughput and pressure adjustments while reducing equipment costs and increasing reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single large high-pressure air compressor is used to compress all air, then investment costs are reduced through standardization, but the compressor becomes difficult to implement at very high powers and requires complex and expensive starting equipment
Solution Approach 1:
The patent divides the single large compressor function into multiple smaller compressors (typically 2-6 compressors). Each compressor handles a portion of the total air flow, allowing them to operate at manageable power levels without requiring complex starting equipment, while collectively achieving the required throughput for large-scale air separation.
2Power
If synchronous motors are used for high-power compressors beyond 25 MW, then power requirements are met, but the technology becomes limited and requires very great industrial risk
Solution Approach 1:
By segmenting the total power requirement into multiple smaller compressors, each driven by an asynchronous motor below 25 MW, the system avoids the reliability issues and technological limitations of synchronous motors while still meeting the total power requirements for large-scale operation.
3Ease of manufacture
If a single high-pressure compressor is used, then equipment cost breakdown shows 45-50% for compression function, but reducing costs and increasing reliability of compressors and motors is a priority
Solution Approach 1:
Multiple smaller compressors with asynchronous motors eliminate the need for expensive starting equipment and regulators required by single large compressors, thereby reducing the 45-50% compression function cost while simultaneously improving reliability through simpler, more robust motor technology.
4Ease of manufacture
If standardised ranges of air separation apparatus are used up to 700-1000 Mt/day, then engineering costs are limited and purchasing savings are achieved, but these standardised productions do not exactly correspond to customer requirements
Solution Approach 1:
The modular approach of using multiple compressors allows flexible configuration to match various customer requirements. By adjusting the number and capacity of individual compressors within the standardized platform, the system can be adapted to different throughput and pressure requirements while maintaining the cost benefits of standardization.
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 efficient air separation with reduced equipment costs and enhanced reliability by using asynchronous motors, allowing for flexible power distribution and pressure management, thus meeting customer requirements while avoiding the limitations of traditional high-pressure compressor technologies.
Implementation Method 1
each of the N compressors compresses the air at a first pressure above 12 bar absolute and below 30 bar absolute
Implementation Method 2
the air is sent at the first pressure of the N compressors to a single purification unit in order to eliminate the water and carbon dioxide
Implementation Method 3
the purified air is cooled in the purification unit before sending it to a single system of columns in a single cold box where the air is separated by cryogenic distillation
Implementation Method 4
separated into a first flow of enriched oxygen, a second flow of enriched nitrogen and a third flow of enriched argon
Data Source
AI summary
An apparatus for separating air by cryogenic distillation comprises N air compressors (C1, C2, C3) connected so as to receive air at ambient pressure and designed to produce air at a first pressure above 12 bar absolute, N being at least 3, each of the compressors being driven by a single asynchronous motor (M1, M2, M3), the total power of the compressors being at least 10 MW.