Principles Calculation of Mass-Flow-Meter

8/13/2019 Principles Calculation of Mass-Flow-Meter

1/32


2/32

Mass flow meter Direct measurement of true value of

mass flow rate

Principle- an additional movement isimparted to a flowing fluid where by an

intermediate measuring parameter

derived in system


3/32

Turbo flow meter ( massflow) Principleconservation of angular

momentum

Moment of momentum law inturbodynamics


4/32

Turbo flow meter


5/32

Turbo flow meter -construction 2 impellers mounted on coaxial distance

Channels are provided on impellers

Impeller at up stream rotated at const.Speed -by syn. motorgear mechanism

2 impeller driven element- connected to a

spring Stationary discto reduce viscous

coupling b/w impellers


6/32

working Fluid enters the channel of impeller- exert

inertial moment causing a torsion.

Liquid now in II impeller- exert apressure. Rotates driven wheel

Balanced by spring to equilibrium

To which a rotational pickup is attached


7/32


8/32

Mass flow meter Coriolisflow meter Used to find mass flow rates of foams,

slurries, mixtures

Used for sticky, thick viscous fluids likeoils, sand mix, peanut butter


9/32

Principle- coriolisflowmeter Any body moving with a const velocity on

a rotating surface with an angular velocity

will acquire an acceleration F F perpendicular to V &


10/32

Construction workingA U tube flow line is used- suspended on a

cantilever with its two ends supported on

a mounting. -A fluid passed with constant velocity V , -

made to vibrate with angular velocity

-Will produce a torsion deflectionproportional to V


11/32

Bridge Type flow meter


12/32

Bridge type flow meter Pressure drop across pump proportional

to mass flow

w = K P


13/32


14/32

E = - B.d. v X 10 -8V

Where

B- magnetic flux density

D- diameter of tube

V- velocity of liquid low


15/32


16/32

application Corrosive acids, acid slurries, paper pulp,

detergents etc


17/32

advantages Does not obstruct flow

No moving part

Good accuracy

Reliable

Fast response

Independent of other fluid properties

except conductivity


18/32

Disadvantages Pipe should be full

Expensive for small pipes

o/p in micro volts so needs amplification


19/32

Ultra sonic transducer Sound travels in material medium

Propagation of sound is modulated by

characteristics of medium High freq >20 K Hzcan be beamed is

used


20/32

Ultra sonic flow meter methods

Doppler

shift

Transit

timeeffect


21/32

Doppler shift Particles in fluid impart a freq. Shift

proportional to particle velocity


22/32

Transit time type


23/32

Phase shift = 2 w v b / c2


24/32

Doppler method


25/32

Doppler method


26/32

Laser anemometer Employed where txn of coherent laser

light through fluid is possible

Provide scattering also Doppler phenomena


27/32

Laser anemometer Freq of scattering beam from a moving

object differ from incident beam by a

value proportional to velocity of body Ie, fd propotional to flow velocity


28/32


29/32

Block schematic


30/32


31/32

Disadvantage Less sensitive


32/32

Thank U

Documents

Principles Calculation of Mass-Flow-Meter