Integrated method and unit for air separation by cryogenic distillation and gas cooling
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Solution Overview
Problem
Existing air separation units produce excess nitrogen, which is not utilized efficiently, and existing cooling methods for stored liquids at subambient temperatures are energy-intensive and prone to heat ingress issues, leading to gas formation and increased electric power consumption.
Innovation Solution
Utilizing excess nitrogen from air separation units for direct-contact cooling of water in a tower, which is then used to cool or condense gases from stored liquids, reducing electric power consumption and addressing heat ingress problems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If excess nitrogen from air separation units is discharged to atmosphere, then the air separation unit can operate continuously, but nitrogen resource is wasted and environmental harm is caused
Solution Approach 1:
The patent converts the harmful excess nitrogen emission into a beneficial cooling resource. The nitrogen gas, which would otherwise be wasted and cause environmental harm, is redirected to cooling towers to provide cooling water to the air separation unit and other equipment, transforming a waste stream into a useful coolant that reduces overall energy consumption.
Solution Approach 2:
The patent creates a multi-functional system where the cooling tower serves multiple purposes: it cools the air separation unit, cools other process equipment, and simultaneously utilizes the excess nitrogen as a cooling medium. This multi-functionality allows the system to address both the nitrogen waste problem and the cooling demand of various units within a single integrated approach.
2Reliability
If electric refrigerator is used to cool water to condense gas from stored liquid, then gas condensation can be achieved, but electric power consumption is high
Solution Approach 1:
The patent implements a self-service cooling system where the air separation unit's own excess nitrogen is used to cool water that then cools and condenses gases from stored liquids. This eliminates the need for external electric refrigeration, as the system uses its own waste nitrogen stream to provide the cooling function, significantly reducing electric power consumption while maintaining reliable gas condensation.
Solution Approach 2:
The patent introduces cooled water as an intermediary medium between the excess nitrogen and the gas that needs condensation. The nitrogen first cools the water in a cooling tower, and then this cooled water is used to condense the gas from the stored liquid. This two-stage indirect cooling process is more energy-efficient than direct electric refrigeration while achieving the same condensation result.
3Stability of the object's composition
If insulation of liquid store is improved to prevent heat ingress, then liquid storage stability is improved, but equipment complexity and cost increase
Solution Approach 1:
Instead of solely relying on improved insulation to prevent heat ingress, the patent converts the inevitable heat ingress into a beneficial effect. The heat entering the liquid store causes gas formation, and this gas is then condensed by the cooled water system, with the condensation process actually helping to maintain storage stability by removing evaporated components and preventing pressure buildup.
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 effectively reduces electric power consumption by using excess nitrogen to cool and condense gases from stored liquids, while minimizing heat ingress and providing a sustainable method for managing excess nitrogen production.
Implementation Method 1
cooling water in a direct-contact tower fed at the bottom with cold nitrogen gas and at the top by the water to be cooled
Implementation Method 2
cooling a gas originating from a store which contains a liquid... in a heat exchanger via indirect exchange
Implementation Method 3
The cooled water is then used to cool, or even to condense a gas originating from a store of a liquid at a subambient temperature
Data Source
AI summary
According to an embodiment of the invention, nitrogen gas of an air separation unit is used to cool the gas formed in a reservoir of liquid from an MEOH unit that is supplied with oxygen by said air separation unit.