As we know the accuracy of thermal mass flow meter is easy be infused when medium measured contain vapor. So vortex flowmeter is more often used to saturated steam and superheated steam measuring, besides vortex flowmeter are better than thermal mass flow meter in range ration. Comate vortex flowmeter range ration can be 1:35.
How to choose the dimension is right for your working condition?
Steam is a compressible fluid and volume varies with the temperature and pressure changes that make steam measurement by mass flow. Besides, mass flow is the first step to calculate the steam energy in custody transfer.
Vortex meter based on Karmen vortex street theory is widely used in the fluids measurement system, especially it’s a perfect skill act in steam, gas, and the clean, non-conductive liquid flow process measurement system.
Steam mass flow Equation:
M; steam mass flow, unit is kg/hr or T/hr;
ρ : density of steam, unit is kg/m3;
V: velocity of flow meter, unit is m/s;
D: pipe inner size, unit is mm;
Conditions: under given pipe size: DN50, working condition at 7barG, T= 170℃
Calculation of saturated steam
Temperature and pressure are dependent variables, density can be calculated by measuring one single factor
according to steam table:
density= 4.218 kg/m3;
V: 2~70m/s of VFM60MV;
M=59.6 ~ 2085.2kg/hr;
Calculation of superheated steam
Temperature and pressure are independent variables. Needed to measure both factors to calculate the density to know mass flow then. For example, P=7barG, T=225℃
Calculation of velocity
Take above case, mass flow around 1200kg/hr in DN50 pipe, pressure at 7barG, T= 170℃;
density = 4.218kg/m3, to get F = 284.5m3/hr;
So velocity is 40.2m/s