Discussion on replacing orifice flowmeter with vor

2022-08-09
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Discussion on replacing orifice flowmeter with vortex flowmeter

1. The current technical level of vortex flowmeter and orifice flowmeter

the basic structure of vortex flowmeter is composed of vortex generator, detection element and signal processing and amplification circuit. At present, the research on vortex generator has reached a fairly perfect level, with triangular generator as the best type, and the detection elements include thermistor, strain gauge, piezoelectric crystal, differential capacitance Ultrasonic wave, etc. Many signal processing parts have been computerized. Vortex flowmeter has the advantages of convenient installation (can be installed directly on the pipeline), small volume, strong interchangeability, long-term operation, and high width of rectangular cross-section at the clamping end. It can be applied to the measurement of most liquids, gases and vapors. At present, the sales volume of vortex flowmeter in the world market increases by about 30% every year

at present, the technical development level of orifice flowmeter is still based on the determined empirical formula. In 1980, the international organization for standardization merged r541 and r781 into iso5167 (1980)

Due to its simple structure, low cost, reliability and other advantages, orifice throttling device is applicable to almost all media measurement, while the supporting differential pressure transmitter has developed rapidly, making up for its own shortcomings

2. Comprehensive performance evaluation of vortex flowmeter and orifice flowmeter

orifice flowmeter (hereinafter referred to as orifice) is composed of throttling parts, pressure taking devices and differential pressure transmitters. Heat tracing measures are required for impulse piping in places that are easy to freeze. There are about 20 static sealing points in a flow measurement circuit. There are the following problems in use:

easy to freeze, easy to block, easy to leak, heat tracing, easy to cause aging of differential pressure transmitter components In some cases, isolation liquid needs to be added to the impulse pipe. Due to heat tracing or unstable process operation, the isolation liquid lines of positive and negative impulse pipes are often unequal, resulting in liquid column difference, which makes the flow indication inaccurate

although the expectation of function is higher and higher

above will change the flow coefficient, reduce the measurement accuracy, shorten the pipe, and install the differential pressure transmitter directly on the pipe, there is still a dead zone of flow

vortex street flowmeter (hereinafter referred to as vortex street) has only three static sealing points, which is not easy to leak, has no dead zone of flow, does not need heat tracing and insulation, is not affected by fluid gravity, temperature, pressure, viscosity, etc., and the flow coefficient remains unchanged for a long time

but when vortex street is used in vibration occasions, the flow measurement will be inaccurate. At present, anti vibration vortex street has been introduced in the market to overcome the influence of vibration on the inaccuracy of flow measurement. (end)

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