Why do gas vortex flowmeters come with temperature and pressure compensation?

Project Overview

In order to ensure the accuracy of the measurement results, temperature and pressure compensation is required when measuring gas vortex flowmeters. That is, the measurement results are corrected for temperature and pressure data, and the measurement results under working conditions are converted into the measurement results under corresponding standard conditions.

1. Principle of temperature and pressure compensation

The core of temperature and pressure compensation is to establish the corresponding relationship between fluid flow, temperature and pressure through mathematical models or experimental data, and based on this Make corrections to the original reading of the flow meter. Generally speaking, the compensation process can be divided into the following steps:

• Data collection: The temperature and pressure data of the fluid are collected in real time. These data are the basis for subsequent compensation calculations.

• Model establishment: Based on the physical properties of the fluid, establish a mathematical model between flow, temperature, and pressure. This model is usually based on fluid mechanics principles, thermodynamic laws and experimental data fitting.

• Compensation calculation: Substitute the collected temperature and pressure data into the compensation model, calculate the flow deviation caused by temperature and pressure changes, and deduct it from the original reading of the flow meter This deviation results in a compensated accurate flow value.

• Result display: Display the compensated flow value for user reference or use.

2. Choose different temperature and pressure compensation methods according to the measurement medium

• When measuring gas, temperature and pressure need to be compensated at the same time. Due to the compressibility of dry gas, its flow measurement is more complicated than that of liquid. In addition to the input signal, the output signal of the gas flow meter is also related to the gas density, and the density of the gas is a function of temperature and pressure. Gases are generally settled based on standard volume flow rates. When the volume, temperature or pressure of the gas changes, the flow rate will change accordingly. Without temperature and pressure compensation, the measured gas flow rate will certainly not be accurate. Therefore, the temperature and pressure of the gas to be measured are introduced into the flow measurement system during measurement, and the accuracy of the measurement results is ensured through conversion compensation.

  

• When measuring saturated steam, single temperature compensation or single pressure compensation is required. The density of saturated steam has a fixed corresponding relationship with temperature or pressure (saturated steam density table). If you know any of them, you can determine the density of saturated steam.

• When measuring superheated steam, temperature and pressure need to be compensated at the same time. Because either temperature or pressure changes, the density of the steam changes and the mass flow rate changes accordingly.

• When measuring liquids, pressure compensation is generally not required. Below 5MPa, only the influence of temperature is generally considered. Temperature compensation is required for accurate measurement. In general measurements, you do not need to use any compensation; when measuring some hydrocarbons (such as crude oil), simultaneous compensation of temperature and pressure is generally required.

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