Cryogenic Nitrogen Column Flooding Control via Rich Liquid Vaporization
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Solution Overview
Problem
In self-refrigerated cryogenic nitrogen gas generators, excess refrigeration produced by the cryogenic expansion turbine cannot be effectively removed when the liquid nitrogen storage tank is full, leading to potential process disruptions due to column flooding.
Innovation Solution
A method involving the sensing of a rising rich liquid level, transferring it to a vaporizer outside the cold box, converting it to gas, and returning the gas to the distillation column to absorb excess refrigeration, thereby stabilizing the column and preventing flooding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the liquid nitrogen storage tank is filled to capacity to maximize product storage, then the storage capacity is improved, but the ability to remove excess refrigeration is lost causing column flooding
Solution Approach 1:
A level-controlled valve is introduced as an intermediary mechanism between the liquid nitrogen storage tank and the distillation column. When the tank reaches capacity, the valve automatically opens to allow excess rich liquid to bypass into the condenser, preventing column flooding while maintaining full storage capacity. This intermediary device resolves the contradiction by providing an automatic relief path that activates only when needed.
2Power
If the cryogenic expansion turbine operates at full capacity to maximize refrigeration production, then the refrigeration capacity is improved, but excess refrigeration accumulates causing harmful effects when the storage tank is full
Solution Approach 1:
The system implements a feedback mechanism where the liquid level in the storage tank is continuously monitored. When the tank reaches capacity, the level signal triggers the control valve to open, creating a bypass path for excess rich liquid to the condenser. This feedback loop allows the turbine to maintain full refrigeration capacity while automatically diverting excess refrigeration effects when storage is full, preventing harmful accumulation.
3Stability of the object's composition
If the rich liquid level is maintained at normal levels to prevent column flooding, then the process stability is improved, but the ability to store liquid nitrogen product is reduced
Solution Approach 1:
The system segments the rich liquid flow path into two separate channels: a primary path through the distillation column for normal operation, and a secondary bypass path through the condenser for excess removal. The level-controlled valve acts as a switch between these segments, allowing the column to maintain stable normal levels for process stability while the bypass segment handles excess storage capacity needs, resolving the contradiction between stability and storage capacity.
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 method efficiently removes excess refrigeration, preventing column flooding and maintaining process stability by utilizing the heat from the returned gas to manage excess refrigeration, allowing continued operation without the need for liquid nitrogen product removal.
Implementation Method 1
adding heat to the removed rich liquid and converting the removed rich liquid into gas, in said vaporizer apparatus
Implementation Method 2
utilizing heat from the returned gas in the column to remove excess refrigeration from the rich liquid remaining in the column
Implementation Method 3
Many of them use a cryogenic expansion turbine to extract work and produce refrigeration
Data Source
AI summary
The method of adding heat to refrigerated rich liquid that accumulates in a reservoir in a distillation column, to prevent the column from flooding, that includes the steps sensing a rise in rich liquid level to predetermined level in the reservoir, removing rich liquid from the reservoir in response to said sensing, to flow to vaporizer apparatus outside a cold box containing said column, adding heat to the removed rich liquid and converting the removed rich liquid into gas, in said vaporizer apparatus, returning said gas to the distillation column, and utilizing heat from the returned gas in the column to remove excess refrigeration from the rich liquid remaining in the column, thereby stabilizing the column against flooding.