Coriolis effect
The basis of the Kryulis flowmeter is Newton’s second law of motion in which
Force = mass * acceleration
A common way to measure the mass of an object is to weigh it. In weight measurement, the force is calculated at a known acceleration. The basis of this type of measurement for fluids in motion, especially inside the tube, is not simple or impossible.
However, it is possible to change the above formula and apply a known force and instead measure its acceleration to determine the mass.
The effect of cryolysis when the discharge moves outwards in the rotating part of the tube causes the opposite force and vice versa causes a forward force in the part of the tube for the discharge that moves towards the axis of rotation.
When the axial full section of the tube moves oscillating, the outlet section of the tube is obstructed and the return section is advanced, causing twisting in the tube.
Performance basis:
It has been proven that in the Coriolis mass thermometer, it is possible to record the total mass flow rate with an accuracy of better than 0.1%. Each Coriolis has its own calibration factor, which depends on the geometric information and specifications of the materials used. Therefore, the separate calibration factor is a process fluid. The basis of the operation of this equipment is based on the Coriolis force , which manifests itself as a rotating or oscillating system. The duct is stimulated by an external force. The excitation frequency is kept separate from the normal frequency to minimize the energy required for oscillation. When there is no flow inside the measuring tube, the Coriolis force is zero. When the fluid begins to move, the Coriolis force is no longer zero. In the power input sectionCoriolist tends to slow down the oscillating duct and instead tends to accelerate at the output of the Coriolis force. In the middle of the Coriolis duct, the force is always zero because in this case the vector is zero for the direct duct and is equal to the curved duct, resulting in a value equal to zero. As soon as the fluid begins to flow, the Coriolis force shifts the metal along the duct. This phase shift is proportional to the mass flow. Mass flow can be determined by measuring the phase shift between the two positions of the sensor. Since the oscillation frequency is kept at the normal frequency of the system, this frequency also changes by changing the density inside the duct. The natural frequency increases with decreasing density. Therefore, knowing the natural frequency of the system, the density of the fluid can be calculated directly. Another direct measurement made by the device is the temperature of the fluid.
Balanced measurement system:
The balanced measurement system includes the following two types:
-Two measuring ducts
-Single measuring tube
Two measurement ducts:
The operation of this equipment is based on the production of Coriolis forces . These forces exist when transient motion and rotational motion occur simultaneously.
The straight-line tubular type is an advanced type of cryolysis loop measurement that has the advantage of reducing pressure drop.
Rotational motion in this type of measurement is provided by the vibration of the tubes and the Coriolis force propagates inside the tubes. The tubes begin to vibrate as they intensify, and sensors are used to detect the movement of the tubes. In the common model, similar to the two branches of the tuning fork, the two cryolysis ducts oscillate normally and without discharge. Dubai-induced cryolysis forces cause phase shifts in duct oscillations. When the fluid flow rate is zero, in a state where the fluid is constant, both ducts oscillate in parallel. When there is a mass flow, the oscillation of the duct at the inlet of the hive at the outlet becomes faster. This is because the fluid accelerates at the input and decreases at the output.
As the mass flow rate increases, so does the phase difference.
Measurement duct oscillations are detected at the input and output by electrodynamic sensors. The basis of measurement in this method is independent of the temperature of the pressurizers on the conductivity or shape of the fluid flow.
Single duct measuring:
In this method, like two measuring pipes, the basis of the work is the same as the oscillation of the pipe. The Coriolis forces created by the measuring duct cause the phase shift to oscillate.
When the flow rate is zero, the fluids are constant. The oscillations recorded at the points are in phase and there is no difference between them.
The mass flow slows down the oscillation at input 2 and increases at output 3.
Compared to two-channel systems in this method is a system and solution for duct balance.
Installation according to 2002 standard:
Although Coriolis flowmeters are designed to withstand pipe vibrations, vibrations at frequencies close to the sensor can have a serious impact on measurement accuracy. The sensor should be kept away from vibration sources such as pumps, compressors and motors as much as possible.
Elastic interference from several flowmeters: Sensors of the same size and model usually operate at the same frequencies and can interfere with each other. Therefore, if there is a need to install two Cryolis flowmeters in series or in close proximity, the manufacturer of the device should be inquired about the interference.
Impact flow: Hydraulic vibrations close to the operating frequency of the sensor can also affect the accuracy of the measurement. If such a situation exists, it can be useful as a pacemaker.
Rotational and heterogeneous motion of speed: Experiments on several different designs of flowmeters show that the shape of heterogeneous velocity has no effect on the performance of flowmeters or its effect is small. However, it is recommended to operate according to the manufacturers’ recommendations.
Interference of radio and electromagnetic waves: A strong magnetic field can affect the electromagnetic signals of the sensor. The flowmeter sensor should not be located near sources of electromagnetic and radio interference, such as variable frequency motors, high voltage transformers, or radio transmitters.
Two-phase discharges: These discharges can have a negative effect on the flow meter. If necessary, air or steam extinguishing equipment should be used to install the Cryolis flow meter.
Tube filling: Cryolysis flow meter should be installed in a place that ensures complete filling of the measuring pipe.
Installation of a filter: You can prevent foreign objects from entering the instrument by installing a filter above it.
The material of the duct is mentioned in the standard, if it is not specified, it must be 316 stainless steel.
Advantages
– Independent of temperature, pressure, density, conductivity and high cost;
-Send information of mass flow rate, density and temperature as a sensor;
– Ability to work at high densities;
Conductivity-independent;
Suitable for measuring hydrocarbons;
Suitable for density measurement.
Disadvantages
-expensive;
– The effect of vibration on it;
High installation price;
No need to set a zero point.
Functional limitations:
-high-temperature;
-Vibration;
The amount of gas during the fluid period;
-Limited to low flow rates;
– Limited to use in pipes with a maximum diameter of 150 mm
Summary
Coriolis flowmeters measure mass flow directly and accurately in the path and are independent of temperature, pressure, cost and density. Mass flow, density and temperature can be measured with just one sensor. Calibrated cryolite flow meters can be used for almost any application.
For critical controls, the use of this measurement method is preferred, and due to their high accuracy, the use of this method is very common in controls that are very strict.
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