There are two types of Coriolis mass flowmeters: direct and indirect. In the actual application process, different mass flowmeters will be selected according to different needs.
What is a Coriolis mass flowmeter?
Coriolis mass flowmeters have revolutionized the way industries measure flow rates. These highly accurate devices provide real-time data, making them essential in various industries such as oil and gas, chemical, and food processing. In this comprehensive guide, we will delve into the working principles behind Coriolis mass flowmeters, explore the key differences between them and other flow measurement technologies, and highlight why they are crucial for accurate and reliable flow measurements.
How Does a Coriolis Mass Flowmeter Work?
At the heart of a Coriolis mass flowmeter lies a vibrating tube. When fluid flows through this tube, it is subjected to Coriolis forces, resulting in a phase shift. By measuring this phase shift, the flowmeter can accurately determine the mass flow rate of the fluid. The vibrating tube is typically made of a durable material such as stainless steel to withstand the harsh conditions often encountered in industrial environments.
The working principle of a Coriolis mass flowmeter can be explained as follows: as fluid flows through the vibrating tube, it causes the tube to twist and vibrate. Sensors integrated into the tube measure the phase shift caused by the Coriolis forces. This phase shift is directly proportional to the mass flow rate of the fluid. By analyzing the phase shift, the flowmeter calculates the mass flow rate, providing accurate and reliable measurements.
Coriolis mass flowmeters also have the advantage of being able to measure density and temperature in addition to mass flow rate. This makes them versatile instruments that can provide a wealth of information about the fluid being measured.
Factors to consider when choosing a Coriolis mass flowmeter
1. When choosing a mass flowmeter, you should first consider whether to use a direct type or an indirect type, which can be considered according to the performance characteristics, scope of application, accuracy requirements and cost of the two mass flowmeters.
2. If a high-precision volumetric flow meter (such as (0.2%-0.5%) R volumetric flowmeter) is used in the first-class combined mass flowmeter, its accuracy can reach (0.5%-1%)R between, usually lower. The second type of combination method (dual flow meter method) is between (1%-2.5%) FS.
3. When used for liquid flow measurement, density-volume flow method, temperature-volume flow method or dual flowmeter method can be used. Generally, no pressure correction is needed, because the influence on the liquid density is negligible in the normal range of pressure variation (for example, heavy oil is compressed by 0.45% when the pressure increases from 0.5MP. to 6MP.)c
4. When using the density-volume flow method, the adaptability of the selected density meter to the fluid to be measured should be considered. There are two connection methods for the density of the fluid in the pipeline on the side of the density meter: one is to insert the density meter directly into the pipeline; the other is to connect the density meter directly into the pipeline. Connect the density meter to the branch pipe of the main pipe.
5. Due to the small range of the differential pressure flowmeter in the double flowmeter method, the range of use is affected, but the double flowmeter method can solve the problem of not having a suitable density meter when measuring gas.
6. When measuring gas, the pressure/temperature-volume flow method is the most common.
At present, there are many varieties of such flowmeters, such as flow computers, flow display totalizers with calculation functions, and intelligent flow totalizers, etc. The functions are very different, and detailed information should be obtained from the manufacturer when selecting them. Some models are only suitable for the measurement of near-ideal gases such as air, while others can be used for the measurement of natural gas and steam.
Installation of Coriolis mass flowmeter
Coriolis mass flowmeter is an instrument with low installation requirements for medium flow detection in existing industrial production. Because it can directly detect the quality, density and temperature of the medium flowing through the internal measuring tube of the instrument, there is no strict layer on the flow state of the medium. Therefore, during the installation process, there is no requirement for the straight pipe section of the pipeline before and after the flowmeter. It can be installed arbitrarily like a regulating valve, which greatly facilitates the construction and installation on site.
Coriolis mass flowmeters have various shapes, but their internal structures are almost the same. Basically, they are composed of two U-shaped measuring tubes. Three coils are installed at the bottom and on the left and right sides between the two measuring tubes. The coil at the bottom is the excitation There are two coils on the left and right, one for detecting mass and one for density. In addition, a thermal resistance is buried inside the measuring tube to detect the temperature of the medium. Since the mass flowmeter can detect the density of the medium in real time without the need to manually set a constant density of the medium, the detection value of the mass flowmeter is accurate and reliable, and the construction and installation are simple and convenient.
Although the Coriolis mass flowmeter has no requirements for the front and rear pipelines of the flowmeter during the construction and installation, some details should be paid attention to during the installation process, such as ensuring that the process flanges before and after the flowmeter installation are concentrically welded, which can eliminate the need for the installation process. The additional torque caused by the misalignment of the flange reduces the use error of the mass flowmeter. At the same time, pay attention to some supporting construction processes, especially the influence of eccentric torsion and additional stress on the operation of the flowmeter during the accompanying laying process.
Although the measuring tube of the Coriolis mass flowmeter is inside the casing, the external stress can still cause unmeasurable additional errors in the detection. Stress superposition.
The laying of the companion should also have a certain distance from the mass flowmeter to prevent the influence of the asymmetric stress and excessive conduction heat generated by the accompanying thermal expansion on the temperature detection of the mass flowmeter medium.
The daily maintenance of the Coriolis mass flowmeter is to calibrate the zero point and reset the totalizer.
Affected by the temperature during use and installation, the electronic components and detection sensors of the mass flowmeter in use will have a little temperature drift, and the thermal expansion of the installation flange of the process pipeline will cause some asymmetric stress. Therefore, if you suspect the mass flowmeter If the zero point is inaccurate, zero point calibration can be performed.
When calibrating, the front and rear hand valves of the flowmeter are closed. Generally, to ensure that the medium is full of the mass flowmeter, the rear hand valve of the flowmeter should be closed first, and then the front hand valve should be closed. When putting into use, the front and rear valves should be put into use first, and then the rear valve should be opened.
What is the Difference Between a Coriolis Mass Flowmeter and a Magnetic Flowmeter?
While both Coriolis mass flowmeters and magnetic flowmeters are used to measure flow rates, they operate on different principles. A magnetic flowmeter, also known as an electromagnetic flowmeter, relies on Faraday’s law of electromagnetic induction to measure flow rates. It consists of a pipe with a magnetic field applied across it and electrodes placed at specific points along the pipe. When a conductive fluid flows through the pipe, it generates a voltage, which is proportional to the flow rate.
In contrast, a Coriolis mass flowmeter directly measures the mass flow rate of a fluid. It does not rely on the conductivity of the fluid or the presence of any magnetic fields. This makes Coriolis mass flowmeters suitable for a wide range of fluid types, including non-conductive fluids and those with low conductivity.
What is the Difference Between Coriolis and Turbine Flow Meter?
Turbine flow meters and Coriolis mass flowmeters are two commonly used flow measurement technologies. While both can provide accurate flow rate measurements, they operate on different principles and have distinct applications.
A turbine flow meter consists of a rotor with blades placed in the path of the fluid flow. As the fluid moves through the meter, it causes the rotor to spin. The rotational speed of the rotor is directly proportional to the flow rate. This speed is then converted into an electrical signal, which is used to calculate the flow rate.
In comparison, a Coriolis mass flowmeter measures the mass flow rate of a fluid by analyzing the phase shift caused by Coriolis forces. It does not rely on moving parts like a turbine flow meter, making it more suitable for applications where minimal maintenance and high accuracy are required.
What is the Difference Between Coriolis Flow Meter and Orifice Meter?
Orifice meters and Coriolis flow meters are both widely used in the field of flow measurement. However, they differ in terms of their working principles, accuracy, and suitability for different applications.
An orifice meter consists of a plate with a small hole (orifice) placed in a pipe. As fluid flows through the orifice, the pressure difference across the hole is measured. This pressure difference is then used to calculate the flow rate. Orifice meters are cost-effective and relatively simple to install, but they are less accurate compared to Coriolis flow meters.
Coriolis flow meters, on the other hand, directly measure the mass flow rate of a fluid by analyzing the phase shift caused by Coriolis forces. They are highly accurate and can handle a wide range of fluid types, making them suitable for applications where precise measurements are critical.
Conclusion: Why Coriolis Mass Flowmeters are Essential in Various Industries
Coriolis mass flowmeters have become essential instruments in various industries due to their accuracy, versatility, and reliability. Their ability to provide real-time data on mass flow rate, density, and temperature makes them invaluable in applications such as custody transfer of fluids, batching processes, and quality control.
The unique working principle of Coriolis mass flowmeters, which directly measures the mass flow rate of a fluid, sets them apart from other flow measurement technologies such as magnetic flowmeters, turbine flow meters, and orifice meters. This makes Coriolis mass flowmeters suitable for a wide range of fluid types and applications, ensuring accurate and reliable flow measurements.
In conclusion, if you are looking for precise, real-time flow measurements, Coriolis mass flowmeters are the go-to solution. Their accuracy, versatility, and ability to provide additional information about the fluid being measured make them essential tools in industries where precise flow measurements are crucial. Invest in a Coriolis mass flowmeter and experience the benefits it brings to your flow measurement processes.
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