Cryogenic Air Separation Pump Layout for Stable Oxygen Recovery
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Solution Overview
Problem
Existing air separation unit configurations face challenges in maintaining plant reliability and efficiency due to difficulties in manufacturing pumps that can handle high operating ranges, leading to potential pressure drops and oxygen molecule loss when recycling liquid from storage tanks.
Innovation Solution
A process and apparatus for air separation by cryogenic distillation that uses a single pump or multiple pumps in parallel, where a liquid is withdrawn, pressurized, and either vaporized or recycled back to the column system without passing through the storage tank, ensuring flexibility and stability by utilizing a heat exchanger, cryogenic distillation columns, and a phase separator to manage flow and pressure effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple pumps are installed in parallel to ensure plant reliability and quick takeover capability, then production stability is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The pump system is designed to handle multiple functions: during normal operation it pressurizes liquid for product withdrawal, during turndown it recycles liquid to the column, and during failure it provides quick takeover capability. This multi-functionality resolves the contradiction by making the same pump configuration adaptable to different operational scenarios without requiring additional specialized equipment.
Solution Approach 2:
The system dynamically adjusts pump operation based on production load requirements. During full operation, pumps operate at high capacity for product withdrawal. During turndown, the system switches to recycling mode to maintain column feed. This dynamic adaptability allows reliable quick takeover capability while avoiding the need for permanently complex multi-pump configurations.
2Adaptability or versatility
If pumps are sized to handle high operating ranges for flexibility, then adaptability is improved, but manufacturing precision and operational reliability worsen due to difficulty in manufacturing such pumps
Solution Approach 1:
The pump system is segmented into multiple parallel units, each sized for a specific operating range. During full load, one or two pumps operate at optimal capacity. During turndown, the system uses a different configuration. This segmentation allows each pump to be manufactured with standard precision while the system as a whole achieves high adaptability through flexible configuration.
3Reliability
If liquid is recycled to build up pump load during turndown, then pump operational stability is improved, but oxygen loss increases due to flash in the storage tank
Solution Approach 1:
A flash drum is introduced as an intermediary device between the storage tank and the column. The flash drum allows controlled vaporization of excess liquid to generate column feed without requiring recycling through the storage tank. This eliminates the harmful flash loss while maintaining pump operational stability during turndown conditions.
Solution Approach 2:
The harmful flash loss is extracted and separated from the main liquid flow path. Instead of recycling liquid through the storage tank where flash occurs, the system takes out the vaporization function and places it in a dedicated flash drum, allowing controlled vapor-liquid separation without oxygen loss to the atmosphere.
4Device complexity
If a single pump is used to simplify the system, then device complexity is reduced, but reliability and quick takeover capability worsen
Solution Approach 1:
The system maintains preliminary readiness for failure scenarios by pre-configuring multiple pumps in parallel. While a single pump may suffice for normal operation, the additional pumps remain standby-ready to provide immediate takeover capability upon failure, achieving reliability without significantly increasing operational complexity.
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 configuration ensures quick takeover of production at any load without impacting oxygen recovery, maintaining competitiveness in efficiency and production stability, with improved responsiveness and oxygen recovery rates compared to classical systems.
Implementation Method 1
a) compressed and purified air is cooled in a heat exchanger and then sent to a column of a column system to be distilled
Implementation Method 2
a) compressed and purified air is cooled in a heat exchanger and then sent to a column of a column system to be distilled
Implementation Method 3
Process and apparatus for the separation of air by cryogenic distillation
Implementation Method 4
c) a stored liquid is removed from the storage tank and pressurized using at least one pump
Implementation Method 5
d) a first stream of pressurized liquid from at least one pump is sent to the heat exchanger and vaporized to form a gaseous product
Implementation Method 6
e) a second stream of pressurized liquid from the at least one pump or a fluid derived from the second stream is sent to a column of the column system
Data Source
AI summary
An apparatus and process for separating air by cryogenic distillation includes a heat exchanger, a column system having at least one cryogenic distillation column, a conduit for supplying the column system with cooled air from the heat exchanger, a storage tank, a conduit for removing a liquid from the column system and sending it to the storage tank, at least one pump, at least one conduit for sending pumped liquid from the outlet of the or each pump to the heat exchanger, at least one conduit connected to the outlet of the pump or at least one outlet of at least one pump and to a column of the column system, said conduit passing directly to the column without passing via the storage tank.