Integrated Nitrogen Liquefier for Flexible Liquid Nitrogen Output
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Solution Overview
Problem
Current cryogenic air separation units are limited in their ability to produce variable amounts of liquid nitrogen while maintaining high nitrogen and argon recoveries, particularly in applications requiring significant liquid nitrogen production or variable production rates.
Innovation Solution
An integrated nitrogen liquefier system that operates in three modes: nil liquid nitrogen, low liquid nitrogen, and high liquid nitrogen modes, utilizing a nitrogen feed compressor, recycle compressor, warm and cold booster compressors, and turbines, with an oxygen-enriched stream used as a condensing medium in the argon condenser to enhance recovery efficiencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a cryogenic air separation unit is designed for gas-only argon and nitrogen production, then argon and nitrogen recoveries are improved, but the unit cannot produce liquid nitrogen when required
Solution Approach 1:
The nitrogen liquefier is designed to operate in multiple modes (high liquid nitrogen mode, low liquid nitrogen mode, and no liquid nitrogen mode) to provide universal functionality. The system can produce liquid nitrogen when needed while also operating efficiently in gas-only mode, making the air separation unit adaptable to various customer requirements without requiring separate dedicated systems
2Quantity of substance
If liquid nitrogen production is increased to meet customer demands, then liquid nitrogen availability is improved, but nitrogen recovery from the distillation column system deteriorates
Solution Approach 1:
The nitrogen liquefier receives its feed from the gaseous nitrogen product stream after it has been produced by the distillation column system. By positioning the liquefier downstream and using a portion of the already-separated nitrogen gas as feed, the system can produce liquid nitrogen without interfering with the distillation column's nitrogen recovery efficiency. The liquefier operates independently on a diverted portion of the nitrogen stream
3Adaptability or versatility
If the air separation unit is configured for moderate pressure argon and nitrogen production, then argon and nitrogen recoveries are improved, but the unit lacks flexibility for variable liquid nitrogen production
Solution Approach 1:
The nitrogen liquefier is designed with variable operating modes that allow dynamic adjustment of liquid nitrogen production rates. The system can operate in high liquid nitrogen mode for maximum production, low liquid nitrogen mode for reduced production, or no liquid nitrogen mode for gas-only operation. This dynamic capability enables the moderate pressure air separation unit to maintain flexibility while preserving argon and nitrogen recovery efficiencies
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 high recovery of nitrogen and argon with flexible liquid nitrogen production capabilities, maintaining performance across different operating modes without compromising argon or nitrogen recovery in the distillation column system.
Implementation Method 1
a nitrogen feed compressor configured to receive a gaseous nitrogen feed stream and compress the gaseous nitrogen feed stream; a nitrogen recycle compressor configured to receive the compressed gaseous nitrogen feed stream and further compress the compressed gaseous nitrogen feed stream
Implementation Method 2
a warm booster compressor configured to still further compress a first portion of the further compressed warm nitrogen stream to produce a cold nitrogen stream; a cold booster compressor configured to further compress the cold nitrogen stream to produce a primary nitrogen liquefaction stream
Implementation Method 3
a warm booster compressor configured to still further compress a first portion of the further compressed warm nitrogen stream to produce a cold nitrogen stream; a cold booster compressor configured to further compress the cold nitrogen stream to produce a primary nitrogen liquefaction stream
Implementation Method 4
a heat exchanger configured to cool the primary nitrogen liquefaction stream via indirect heat exchange with the warm recycle stream and cold recycle stream to produce a liquid nitrogen product stream
Implementation Method 5
a distillation column system configured for receiving the cooled, compressed and purified air stream and produce at least two or more oxygen enriched streams from the lower pressure column; an argon product stream, a gaseous nitrogen product stream
Implementation Method 6
an argon column arrangement operatively coupled with the lower pressure column, the argon column arrangement having at least one argon column and an argon condenser
Implementation Method 7
an adsorption based pre-purifier unit configured for removing water vapor, carbon dioxide, nitrous oxide, and hydrocarbons from the compressed air stream
Data Source
AI summary
A nitrogen liquefier configured to be integrated with an argon and nitrogen producing cryogenic air separation unit and method of nitrogen liquefaction are provided. The integrated nitrogen liquefier and associated methods may be operated in at least three distinct modes including: (i) a nil liquid nitrogen mode; (ii) a low liquid nitrogen mode; and (iii) a high liquid nitrogen mode. The present systems and methods are further characterized in an oxygen enriched stream from the lower pressure column of the air separation unit is an oxygen enriched condensing medium used in the argon condenser.