Cryogenic Liquid Metering with Stabilizing Column
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Solution Overview
Problem
Existing cryogenic liquid metering systems face challenges in accurately determining the density of LNG due to the unknown composition and dynamic nature of the fluid, leading to issues with temperature-based compensation and noise in pressure sensors.
Innovation Solution
A system with a metering element submerged in the cryogenic liquid, featuring multiple pressure sensors and a stabilizing column to minimize noise and accurately determine density, combined with a recirculation line and spray orifices to collapse vapor, and a temperature probe to calculate the percentage of components based on temperature and pressure data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If temperature-based density compensation is used, then density determination is simplified, but accuracy deteriorates due to unknown LNG composition
Solution Approach 1:
The patent replaces temperature-based density compensation with a differential pressure-based measurement system. Instead of using temperature sensors and lookup tables, the system uses differential pressure sensors to directly measure density through the relationship between pressure differential and fluid density in a known geometry, providing accurate composition-independent density determination.
Solution Approach 2:
The patent changes the measurement parameter from temperature to differential pressure. By measuring the pressure differential across a known vertical height in the stabilizing column, the system directly determines density without relying on temperature-compensation models that are invalid for unknown LNG compositions.
2Productivity
If pressure sensors are used to determine density in dynamic flow, then real-time measurement is achieved, but noise increases due to dynamic nature of cryogenic liquid flow
Solution Approach 1:
The patent extracts the pressure measurement function from the dynamic flow environment by introducing a stabilizing column. The differential pressure sensors measure pressure in the stabilizing column where flow is minimized, separating the measurement function from the dynamic dispensing flow to eliminate noise while maintaining real-time capability.
Solution Approach 2:
The stabilizing column acts as an intermediary between the dynamic dispensing flow and the pressure sensors. It provides a quiescent measurement zone where the cryogenic liquid stabilizes, allowing accurate pressure differential measurement without the noise of dynamic flow, while still reflecting the overall fluid density.
3Ease of manufacture
If vapor is present in the metering chamber, then filling is simplified, but measurement accuracy deteriorates due to two-phase flow effects
Solution Approach 1:
The patent utilizes phase transition (vapor collapse) as a beneficial mechanism. The spray orifices intentionally collapse vapor in the headspace, creating a liquid-filled environment that eliminates two-phase flow effects and ensures accurate single-phase metering, while the vapor phase initially simplifies filling operations.
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 provides accurate and robust metering of cryogenic liquids by minimizing noise and accurately determining density, ensuring precise measurement of LNG and other cryogenic fluids, with no moving parts and the ability to calibrate for various densities.
Implementation Method 1
a stabilizing column to minimize noise and accurately determine density
Implementation Method 2
a fill line including a plurality of spray orifices positioned within a head space of the metering chamber so that cryogenic liquid passing through the spray orifices collapses vapor in the head space
Implementation Method 3
first and second pressure sensors in communication with an interior of the stabilizing column wherein the first pressure sensor is configured to detect a first pressure within the interior of the stabilizing column and the second pressure sensor is configured to detect a second pressure within the interior of the stabilizing column
Implementation Method 4
a temperature probe to calculate the percentage of components based on temperature and pressure data
Data Source
Figure 1
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AI summary
A system for dispensing a cryogenic liquid includes a storage tank containing a supply of the cryogenic liquid and a metering chamber. A liquid inlet line is in communication with the storage tank and the metering chamber so that the metering chamber receives cryogenic liquid from the storage tank. A meter run is in communication with the metering chamber and includes a metering element, a dispensing line and a dispensing valve. A stabilizing column is positioned within the metering chamber and includes vertically spaced openings. Vertically spaced first and second pressure sensors are in communication with the interior of the stabilizing column. A controller is in communication with the metering element, the first and second pressure sensors and the dispensing valve.