Argon Reflux Condensation with Proportional LOX Flow Control
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Solution Overview
Problem
The existing method of using once-through heat exchangers to condense argon-rich vapor in air separation units faces challenges with dry out and flammability hazards due to high boiling temperature hydrocarbons freezing and concentrating, leading to control issues with crude liquid oxygen flow rates.
Innovation Solution
Implementing a system with multiple once-through heat exchangers connected to an argon column, where crude liquid oxygen flow transducers and controllers ensure proportional flow rates based on vaporization surface areas, and temperature sensors adjust flow to prevent dry out and maintain equal temperatures, thereby controlling the reflux and product flow rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If once-through heat exchangers are used to condense argon-rich vapor, then device complexity is reduced and cost is lowered, but dry out occurs and flammability hazards arise due to hydrocarbon concentration
Solution Approach 1:
The patent implements flow transducers to measure crude liquid oxygen flow rates and controllers to adjust flow distribution to multiple heat exchangers. This feedback control system prevents dry out conditions by ensuring adequate liquid flow, thereby eliminating the flammability hazard while maintaining the simplified once-through heat exchanger structure.
Solution Approach 2:
The patent introduces flow transducers and controllers as intermediary devices between the crude liquid oxygen source and the heat exchangers. These intermediaries monitor and regulate the liquid flow, preventing hydrocarbon concentration and flammability while preserving the cost-effective once-through heat exchanger design.
2Object-affected harmful factors
If crude liquid oxygen flow rate is increased to prevent dry out, then flammability hazard is reduced, but control difficulty increases due to head loss and flashing
Solution Approach 1:
The patent divides the crude liquid oxygen flow into multiple separate streams, each fed to individual heat exchangers through dedicated conduits with individual flow control. This segmentation allows precise control of each stream's flow rate, preventing flashing and control difficulties while ensuring adequate flow to prevent dry out and flammability.
Solution Approach 2:
The patent introduces flow transducers and controllers as intermediary devices to measure and regulate crude liquid oxygen flow rates. These intermediaries provide precise control capability, enabling the system to maintain adequate flow rates to prevent dry out and flammability without suffering from control difficulties or flashing issues.
3Reliability
If multiple heat exchangers are used with proportional flow control, then dry out is prevented and operation is stabilized, but device complexity increases
Solution Approach 1:
The patent divides the condensation system into multiple independent heat exchanger units, each receiving a controlled portion of the crude liquid oxygen flow. This segmentation provides redundancy and stability - if one unit experiences issues, others continue operating - while the proportional flow control ensures each unit receives adequate liquid to prevent dry out.
Solution Approach 2:
The patent implements proportional flow control that adjusts the distribution of crude liquid oxygen to multiple heat exchangers based on their vaporization surface areas. By changing the flow rate parameter proportionally to match heat exchange capacity, the system achieves stable operation and prevents dry out without requiring excessive complexity in the control system.
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 solution effectively controls the flow rates of crude liquid oxygen and argon-rich vapor, preventing dry out and flammability hazards, ensuring efficient condensation and reflux production while maintaining stable operation in air separation units.
Implementation Method 1
argon-rich vapor streams are condensed in once-through heat exchangers connected to an argon column
Implementation Method 2
argon-rich vapor streams composed of argon-rich vapor column overhead are condensed within condensation passages of the once-through heat exchangers
Implementation Method 3
crude liquid oxygen streams composed of a crude liquid oxygen column bottoms of the higher pressure column are partially vaporized in the vaporization passages of the once-through heat exchangers through indirect heat exchange
Data Source
AI summary
An argon reflux condensation system and method in which a plurality of once-through heat exchangers are connected to an argon column of an air separation plant to condense argon-rich vapor streams for production of reflux to the argon column. Condensation of the argon-rich vapor streams is brought about through indirect heat exchange with crude liquid oxygen streams that partially vaporize and are introduced into a lower pressure column of the plant for further refinement. The flow rate of the crude liquid oxygen streams are sensed and controlled at locations in the plant where the crude liquid oxygen is in a liquid state and in proportion to the size of the once-through heat exchangers. Feed stream flow rate to the argon column is controlled in response to air flow rate to the plant and product flow rate is controlled in response to the feed stream flow rate to the argon column.