Cryogenic Neon Recovery With Xenon-Krypton Co-Production
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Solution Overview
Problem
Current rare gas recovery systems from cryogenic air separation units suffer from low neon recovery efficiency and significant liquid nitrogen consumption, impacting the production of other air separation unit products, and lack efficient co-production of xenon and krypton.
Innovation Solution
A system comprising a non-condensable stripping column and a xenon-krypton column, thermally linked via an auxiliary condenser-reboiler, with a reflux condenser, to produce a crude neon vapor stream with greater than 50% neon mole fraction and co-produce xenon and krypton, minimizing liquid nitrogen consumption and impact on argon recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a stand-alone neon purification train with non-condensable stripping column is used, then neon recovery is achieved, but liquid nitrogen consumption is high and impacts other product production
Solution Approach 1:
The patent combines the neon stripping column with the argon purification train by using the same liquid nitrogen source and integrating the overhead streams. The neon stripping column overhead is merged with the argon purification train overhead, allowing simultaneous neon and argon recovery while sharing liquid nitrogen consumption, thereby reducing the overall impact on other products.
Solution Approach 2:
The liquid nitrogen stream from the air separation unit serves multiple functions: it provides refrigeration for the neon stripping column, acts as a stripping medium for neon recovery, and is integrated with the argon purification process. This multi-functional use maximizes the utility of the liquid nitrogen while minimizing waste and impact on other products.
2Quantity of substance
If a large flow of nitrogen is taken from the air separation unit for neon recovery, then neon concentration in crude product is improved, but liquid nitrogen reflux to lower pressure column is reduced, adversely impacting separation of other products
Solution Approach 1:
The patent merges the neon recovery process with the argon purification train by combining their overhead streams and using a shared liquid nitrogen source. This integration allows the system to achieve adequate neon concentration while reducing the total liquid nitrogen withdrawal from the air separation unit, as the argon train also benefits from the same refrigeration source.
Solution Approach 2:
The system optimizes operating parameters such as the flow rate of liquid nitrogen to the stripping column, the pressure differential across the column, and the temperature profile to maximize neon concentration in the crude product while minimizing liquid nitrogen consumption. By carefully controlling these parameters, the system achieves high neon concentration without excessively reducing liquid nitrogen reflux to other columns.
3Ease of manufacture
If crude neon vapor stream with high neon concentration is produced, then downstream processing cost is reduced, but liquid nitrogen usage and compression power requirements increase
Solution Approach 1:
The system optimizes the operating parameters of the neon stripping column, including temperature, pressure, and liquid nitrogen flow rate, to achieve an optimal balance between crude neon concentration and energy consumption. By adjusting these parameters, the system produces a crude neon stream with sufficient concentration for cost-effective downstream processing while minimizing the energy required for compression and liquid nitrogen usage.
Solution Approach 2:
The integrated system maintains continuous operation of the neon stripping column with steady liquid nitrogen flow, ensuring consistent crude neon product quality. This continuous operation avoids the energy penalties associated with start-stop operations and maintains optimal thermodynamic conditions for efficient neon recovery with minimized energy consumption.
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
Achieves overall neon recovery of greater than 95% with minimal liquid nitrogen consumption and minimal impact on argon recovery, while efficiently co-producing commercial quantities of xenon and krypton.
Implementation Method 1
thermally linked via an auxiliary condenser-reboiler
Implementation Method 2
reflux condenser configured to receive the non-condensable containing vent stream and a condensing medium, the reflux condenser further configured to produce a condensate
Implementation Method 3
non-condensable stripping column configured to receive a portion of a liquid nitrogen condensate stream and a stream of nitrogen rich shelf vapor to produce a liquid nitrogen column bottoms and a rare gas containing overhead
Implementation Method 4
xenon-krypton column configured to receive a first stream of liquid oxygen pumped from the lower pressure column and a first boil-off stream of oxygen rich vapor to produce a xenon and krypton containing column bottoms and an oxygen-rich overhead
Data Source
AI summary
A system and method for recovery of rare gases such as neon, helium, xenon, and krypton in an air separation unit is provided. The rare gas recovery system comprises a non-condensable stripping column linked in a heat transfer relationship with a xenon-krypton column via an auxiliary condenser-reboiler. The non-condensable stripping column produces a rare gas containing overhead that is directed to the auxiliary condenser-reboiler where most of the neon is captured in a non-condensable vent stream that is further processed to produce a crude neon vapor stream that contains greater than about 50% mole fraction of neon with the overall neon recovery exceeding 95%. The xenon-krypton column further receives two streams of liquid oxygen from the lower pressure column and the rare gas containing overhead from the non-condensable stripping column and produces a crude xenon and krypton liquid stream and an oxygen-rich overhead.