Partitioned Cryogenic Storage Tank Ullage Management
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Solution Overview
Problem
Existing cryogenic storage tanks face challenges in minimizing heat leak and efficiently managing the ullage space during filling and re-filling, leading to reduced storage times and potential blockages due to restricted fluid passages and pressure differentials.
Innovation Solution
A cryogenic storage tank design with a partitioned cryogen space featuring two fluid passages through the partition, where the first passage allows for bidirectional flow and is sized to prevent back-pressure increase during filling, and the second passage has a constricted area to maintain pressure differential and prevent vapor escape, utilizing a valve mechanism actuated by fluid forces to regulate flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a single restricted fluid passage is used to prevent ullage space filling during filling, then the vapor space is preserved, but the flow rate of cryogenic fluid delivery is reduced and blockages may occur
Solution Approach 1:
The single fluid passage is divided into two separate passages: a first fluid passage with a larger cross-sectional area for maintaining vapor space and preventing blockages, and a second fluid passage with a smaller cross-sectional area for flow restriction during filling. This segmentation allows each passage to serve its specific function optimally without compromising the other.
2Quantity of substance
If the flow area of the fluid passage is made smaller to restrict liquid flow into ullage space, then vapor space is maintained, but the passage becomes more prone to blockages
Solution Approach 1:
The fluid passage system is segmented into two passages with different cross-sectional areas. The first passage has a larger area that is less prone to blockages, while the second passage has a smaller area that provides flow restriction. This segmentation allows the system to maintain vapor space while reducing blockage risk through the larger first passage.
3Productivity
If the fluid passage is positioned near the bottom of the partition to assist with draining liquefied gas, then drainage efficiency is improved, but more liquefied gas flows into the ullage space during filling
Solution Approach 1:
The fluid passage is divided into two separate passages: the first passage is positioned near the bottom for efficient drainage of liquefied gas, while the second passage provides flow restriction. This segmentation allows the first passage to perform drainage effectively without allowing excessive liquefied gas to enter the ullage space, as the second passage controls the overall flow.
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 design effectively drains liquefied gas from the auxiliary space to maintain a vapor-filled ullage space, reducing the need for vapor venting and ensuring efficient delivery of cryogenic fluid by preventing blockages and prolonging storage times.
Implementation Method 1
a valve that regulates the flow of cryogenic fluid between the two storage spaces
Implementation Method 2
the second passage has a constricted area to maintain pressure differential and prevent vapor escape
Implementation Method 3
cryogenic fluids can be stored in thermally insulated storage tanks that consist of an inner storage vessel mounted within an outer shell, with thermal insulation provided by insulating materials and a vacuum disposed in the space between the inner vessel and the outer shell
Implementation Method 4
Heat leak warms the cryogenic fluid which lowers the density of the liquefied gas and increases the bulk temperature and pressure of the cryogenic fluid
Implementation Method 5
the first passage allows for bidirectional flow and is sized to prevent back-pressure increase during filling
Data Source
Figure 1A~1B
Figure 1C
Figure 1D
AI summary
A cryogenic storage tank comprises a partition that divides a cryogen space into a main storage space and an auxiliary space. A valve disposed inside the cryogen space is associated with a first fluid passage through the partition. The valve comprises a valve member that is actuatable by fluid forces within the cryogen space. A second fluid passage through the partition comprises a restricted flow area that is dimensioned to have a cross-sectional flow area that is smaller than that of a fill conduit such that there is a detectable increase in back-pressure when the main storage space is filled with liquefied gas. A preferred method comprises establishing a vapor-filled ullage space when the main storage space is being vented and re-filled with cryogenic fluid, by draining liquefied gas from the auxiliary space through the first fluid passage under the influence of a vapor pressure differential permitted by the partition. If the vapor pressure differential reverses during re-filling, the valve can close to preserve the vapor-filled ullage volume. Re-filling is stopped when an increase in back pressure is detected during re-filling.