Mass flow meters

Mass flow meters

Mass flowmeters Mass flow
meters more accurately calculate the flow rate and, unlike the volume type, do not affect density, pressure and temperature.
Although most flowmeters can infer mass flow from volumetric flow, there are ways to directly measure mass flow, including:

Coriolis meter
flow rate Them Mass Flowmeter
The following methods will explain the above methods.

Coriolis Meter Flowmeters

The effect of cryolysis

The basis of the Kryulis flowmeter is Newton’s second law of motion, in which:
acceleration * mass = force
is a common way of measuring an object by weighing it. In weight measurement, the force becomes a known acceleration (9.81 m / sec2). 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 mass.
The effect of carbulis when the discharge moves outwards, in the rotating part of the tube causes a reciprocal 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 tube part oscillates around its axis, the outlet section of the tube is blocked and the return section is advanced, causing the tube to twist.
Manufacturers of this equipment include Rosemount, Krohne, ABB, Siemens, E&H.

Basic Of Operation

It has been proven that the Kryulis mass flow meter can record the total mass flow rate at an accuracy of better than 0.1%. Each cryolysis has its own calibration factor, which depends on the geometric information and specifications of the materials used. Therefore, a separate and independent calibration factor is a process fluid. The basis of the operation of this equipment is based on the force of carbolis, which manifests itself as a rotating or oscillating system. Such an oscillating system is shown in the figure for a straight duct. The external FE duct is stimulated. The excitation frequency is kept at the normal frequency of the conduit to minimize the energy required for oscillation. The general expression of the creole force Fc = 2m (w * v) where q = mv is the mass flow rate and w is the rotation vector. When there is no flow inside the measuring tube, the cryolysis force is zero (Fc = 0). When the fluid starts to move, the cryolysis force is no longer zero.

In the middle of the conduit, the cryolysis force is always zero because in this case both the vector w for the straight conduit is zero and the vector q or w for the curved conductor are parallel, so q * w is zero. As soon as the fluid starts to move, the cryolysis force causes a phase shift along the duct. This phase shift is proportional to the mass flow. The mass flow can be determined by measuring the phase shift between the sensor positions S1 and s2. Since the oscillation frequency is kept at the normal frequency of the system. As the fluid density inside the duct changes, so does this frequency. The natural frequency increases with decreasing density. Therefore, knowing the natural frequency of the system, the fluid density can be calculated directly. Another direct measurement made by the device is the temperature of the fluid.

Balanced Measuring System

The balanced measuring system includes the following two types:
Two Measurement Tube
(Single Measurement Tube)

Here are two explanations:

The basis of the operation of this equipment is based on the production of controlled crew forces. These forces exist when both transitional motion (straight line) and rotational motion occur simultaneously.
FC = 2. M (W * V)
where:
FC: Cryolite force
M Movable body mass
W: Angular velocity
V: Radial velocity in a rotating or oscillating system
The amount of cryolysis force depends on the mass mass of M, W velocity in the V system and so on Dubai is a crime.
The all-straight tube type is an advanced type of cryolysis loop gauge that has the advantage of reducing pressure drop.

Rotational motion in this type of gauge is provided by the vibration of the tubes and the cryolysis force is transmitted inside the tubes. The tubes begin to vibrate at their resonant frequency, and sensors are used to detect the movement of the tubes. In similar similar models, the two tuning forks oscillate normally in the cryolysis duct without discharge. Flow-induced cryolysis forces cause phase shifts in duct oscillations. When the fluid flow is zero, that is, when the fluid is constant, both ducts oscillate in phase. When there is a mass flow, the oscillation of the duct at the inlet is slow and at the outlet it is faster. This is because the fluid accelerates at the inlet and decreases at the outlet.

As the mass flow rate increases, so does the phase difference (AB). The moving oscillations of the measurement are detected at the input and output with the help of electrodynamic sensors. The basis of measurement in this method is independent of temperature, pressure, viscosity, conductivity or the shape of the fluid jar.

Single Measurement Turbe

In this method, as in the two-way measurement method, the basis of the work is the same oscillation of the duct. The cryolysis forces created in the measuring tube cause the phase shift to oscillate.
When the flow rate is zero, ie the fluid is constant, the oscillations recorded at points A and B are in phase and there is no difference between them.
Mass flow slows down the oscillation at the input and increases it at the output.
Compared to duct systems, this method requires a system and solution for duct balance.
Installation according to API MPMS 5: 2002 Section 6, page 12
Although cryolite flowmeters are designed to withstand tube vibrations, vibrations at frequencies close to the sensor can have a serious impact on measurement accuracy. The sensor should be kept as far away from vibrating sources as possible, such as pumps, compressors and motors.

Vibration interference from multiple flowmeters: Sensors of the same size and model usually operate at the same frequencies and can cause crossstalk. 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 this is the case, using a pulsation dampener may be helpful.
Rotational and non-uniform motion velocity: Experimented in several ways

Different from flowmeters, it shows that the shape of the heterogeneous velocity has no effect on the performance of the flowmeter or its effect is small. However, it is suggested to act according to the suggestions of the equipment manufacturers. Interference of radio and electromagnetic waves: Strong magnetic field can affect the electromagnetic signals of the sensor. The flow meter sensor should not be located near sources of electromagnetic and radio interference such as variable frequency motors, transformers, high voltage radio transmitters.

Two-phase flows: These flows (liquid / gas) can have a negative effect on the flow meter. If necessary, use air or steam destroying equipment to install Karbulis flow meter.

Tube filling: The cryolysis flow meter should be installed in a place that ensures that the measuring tube is completely filled.
Installation of a filter: By installing a filter above the instrument, it is possible to prevent foreign objects from entering it.
The material of the duct components in the IPS-M-IN-130 standard, section 13, if not specified, must be 316 stainless steel.

Advantages

Independent of temperature, pressure, density, conductivity and high
cost Sending mass flow, density and temperature information by sensor
Ability to work at high densities
Independent of conductivity
Suitable for hydrocarbon measurement
Suitable for density measurement

Disadvantages

High price
The effect of vibration on it
High installation price
Need to set a zero point

Application Limitations

High temperatures
Vibration The
amount of gas in the fluid is
limited to low flow rates

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