Process Transmitter Density Measurement via Dual Pressure Couplings
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Solution Overview
Problem
Existing industrial process control systems face challenges in accurately measuring mass flow and level of process fluids due to the need for complex calculations and additional sensors, which are cumbersome, expensive, and prone to errors, especially when determining fluid density for flow rate calculations.
Innovation Solution
A process transmitter that directly measures fluid density using first and second pressure couplings and a secondary sensor, eliminating the need for additional static pressure sensors and equation of state knowledge, and simplifying computational requirements for mass flow calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If additional static pressure sensors are added to measure density accurately, then measurement precision improves, but device complexity and cost increase
Solution Approach 1:
The patent makes the differential pressure sensor perform multiple functions: it measures both the differential pressure for flow rate calculation and the static pressure for density determination. By utilizing the same sensor for both purposes through strategic placement of pressure tap locations, the system eliminates the need for separate static pressure sensors while maintaining measurement accuracy.
Solution Approach 2:
The system uses the measurement data from the differential pressure sensor to derive both flow rate and density information. The processor calculates density by combining the differential pressure measurement with temperature compensation data, allowing the system to self-determine density without requiring additional dedicated sensors.
2Measurement precision
If complex equations with multiple terms are used to calculate flow rate, then measurement precision improves, but computational complexity increases
Solution Approach 1:
The patent pre-calculates and stores flow coefficient values in lookup tables during the design phase, covering a wide range of operating conditions. During actual operation, the processor simply retrieves the appropriate pre-calculated values based on measured parameters and performs straightforward interpolation, avoiding complex real-time calculations while maintaining high accuracy.
Solution Approach 2:
The patent replaces complex analytical calculations with empirical lookup tables and simplified interpolation algorithms. Instead of solving complex differential equations in real-time, the system uses pre-computed data structures that provide accurate results through simple computational operations, significantly reducing processing requirements.
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 improves the accuracy of level and mass flow measurements, reduces computational complexity, and allows for scalable and cost-effective mass flow metering without requiring knowledge of the equation of state, enhancing industrial process monitoring and control.
Implementation Method 1
first and second pressure couplings arranged to receive a first pressure and a second pressure of process fluid in the vessel. These pressures are related to density of the process fluid.
Implementation Method 2
measure the pressure drop across a fixed restriction in the pipe, often referred to as a differential producer or primary element
Data Source
AI summary
A process variable transmitter for measuring a process variable of a process fluid in a vessel includes first and second pressure couplings arranged to receive a first pressure and a second pressure of process fluid in the vessel. These pressures are related to the density of the process fluid. A sensor provides a sensor output related to the process fluid in the vessel. Measurement circuitry is configured to calculate a calculated process variable of the process fluid in the vessel based upon the first and second pressures and the sensed process variable.