Internal Differential Pressure Sensor for Cryogenic Level Measurement
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Solution Overview
Problem
Traditional differential pressure transmitters face accuracy deviations when measuring fluid levels in extreme temperatures due to temperature differences between the fluid in the vessel and the transmitter, especially in cryogenic conditions where fluid density varies significantly with temperature.
Innovation Solution
The impulse tube of the differential pressure sensor is placed inside the vessel, ensuring the fluid temperature in the tube remains substantially the same as the vessel fluid, with options for a retractable cover, hinged area, and reference fluid of matching density to maintain isothermal conditions and consistent pressure measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the differential pressure transmitter is placed outside the vessel, then the device complexity is reduced and ease of operation is improved, but measurement precision deteriorates due to temperature differences between the vessel fluid and transmitter
Solution Approach 1:
The differential pressure transmitter is nested inside the vessel cavity, with the impulse tube extending through the fluid to the measurement point. This internal placement ensures the transmitter experiences the same temperature conditions as the vessel fluid, eliminating thermal drift errors while maintaining measurement functionality.
Solution Approach 2:
The impulse tube serves as an intermediary component that transmits the process fluid from the vessel to the differential pressure transmitter. This mediator allows the transmitter to be positioned inside the vessel while still accessing the fluid at the required measurement point, resolving the conflict between placement location and measurement accuracy.
2Measurement precision
If the impulse tube is filled with process fluid for accurate measurement, then measurement precision is improved, but in cryogenic conditions the fluid density varies with temperature causing measurement errors
Solution Approach 1:
The system changes the physical state parameters of the reference fluid to match the process fluid conditions. By filling both the impulse tube and reference tube with fluids at the same temperature and density, the system compensates for cryogenic temperature effects and maintains reliable measurements across varying thermal conditions.
3Measurement precision
If the impulse tube extends through the cavity to the fluid inlet, then measurement precision is improved by maintaining isothermal conditions, but device complexity increases
Solution Approach 1:
The impulse tube is configured to extend through the vertical dimension of the vessel cavity, reaching from the transmitter location down to the fluid inlet at the bottom. This dimensional arrangement ensures the tube is fully immersed in the process fluid, maintaining thermal equilibrium and isothermal conditions for accurate measurements.
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 configuration enhances measurement accuracy by minimizing temperature deviations, maintaining consistent static pressure, and effectively determining fluid levels even in cryogenic conditions, with optional wireless communication and temperature sensing for precise data transmission.
Implementation Method 1
differential pressure sensor having a first port and a second port, a reference tube that connects the first port of the differential pressure sensor to a bottom portion of the cavity, and an impulse tube that connects the second port of the differential pressure sensor
Implementation Method 2
A portion of the process fluid fills a fluid inlet of an impulse tube of a differential pressure sensor. The pressure difference created by the portion of the process fluid that passes into the fluid inlet compared to a pressure of the reference tube is measured.
Data Source
AI summary
A vessel with a cavity for measuring level is disclosed. The vessel includes a differential pressure sensor having a first port and a second port, a reference tube that connects the first port of the differential pressure sensor to a bottom portion of the cavity, and an impulse tube that connects the second port of the differential pressure sensor to an impulse tube ending. At least a portion of the impulse tube extends through the cavity and ends at a fluid inlet. The fluid inlet is located at a level above the reference tube.