The effect of steam on Rosemount vortex flowmeters

Thread Content

Both the surrounding environment and the conditions present during operation can have an impact on the equipment; a typical example is the Rosemount vortex flow meter! What can affect the measurement of Rosemount vortex flowmeters? For Rosemount vortex flowmeters, the meter coefficient decreases successively in air, water, and steam flow conditions. In air and steam media, the meter coefficient at various points increases as the flow rate increases, which is consistent with theoretical calculations and analyses. Based on the accumulated experimental data, the K value measured when air is used as the fluid medium is 0.2% to 1.0% higher than that measured when water is used as the fluid medium, and it is 1.5% to 3.0% higher when steam is used as the fluid medium. When measuring with high-temperature steam, it is necessary to take into account the effects caused by linear expansion due to temperature; otherwise, the instrument coefficient will be too high. The measurement error resulting therefrom can be temperature-compensated using the formula derived in the article. (2) The effect of the compressibility of gases on the meter coefficient of Rosemount vortex flowmeters is influenced by parameters such as the fluid velocity u, pressure p, density ρ, and the isentropic exponent κ. It is proportional to the velocity u and inversely proportional to the change in p/ρ; the isentropic exponent κ of the gas does not cause a one-way change in the meter coefficient. (3) The compressibility of different media affects the meter factor of Rosemount vortex flowmeters. The meter factor is highest in air, followed by water, and lowest in steam. At the same flow rate, the impact of steam on the meter factor is less than that of air; the specific degree of difference can be determined through analysis and calculation under the given operating conditions. (4) Based on the experimental data, the instrument coefficients of the Rosemount vortex flowmeter measured in different media are consistent with the theoretical calculations, but there is still a certain deviation between the two sets of results. This deviation may be caused by other physical properties of the medium affecting the instrument coefficients; further theoretical analysis is required. In practical applications, it is advisable to use actual flow calibration to determine the instrument coefficients.