Steam flow meter

In recent years, China's natural gas metering technology has made new progress. The steam throttling device and its secondary instrument double-corrugated pipe differential pressure gauge are widely used in China due to their inherent defects, such as the continuous wear and corrosion of steam during use. The combination of on-site resistance components is far more than the standard. 7 kinds of situations; the factors affecting the vortex flow and the pulsating flow are complicated; the adaptability is poor for the gas fluctuation and the high frequency; the pressure guiding tube is easy to cause the signal lag, etc., and the measurement accuracy cannot be guaranteed, which brings the flow worker A new research topic has come.

    The steam we send to the hot users is superheated steam, but after long-distance transportation, as the working conditions (generally temperature and pressure) change, the superheated steam will change from overheating to saturation due to the heat loss temperature. Or supersaturated state (pressure 0.58MPa temperature 164 °C for superheated steam, Dongyue pressure 0.6MP temperature 245 °C, and green beauty food pressure 0.58MP temperature 162 °C), that is to say, the steam received by the remote heat user may change Saturated steam. We usually use dryness X (how much water content in saturated steam) to measure the quality of saturated steam, the best is dry saturated steam, generally called superheated saturated steam, referred to as superheated steam, its water content is negligible (X=1); the wet-saturated steam with poor dryness has a water content of up to 30%, which has the problem of “two-phase flow” of saturated steam.
   The basic principle of the steam flow meter is the Karman vortex principle, that is, "the vortex vortex separation frequency is proportional to the flow rate". The diameter of the flow body of the transmitter is basically the same as the nominal diameter of the meter. A cylinder with an isosceles triangle is inserted into the flow body. The axis of the cylinder is perpendicular to the flow direction of the measured medium, and the bottom surface greets the fluid.
   The steam flowmeter vortex is alternately separated, and pulsating pressure is generated in the wakes on both sides of the cylinder and behind the cylinder. The detection probe disposed inside (or behind) the cylinder is subjected to such a small pulsating pressure to be buried in the The piezoelectric crystal element within the probe is subjected to alternating stress to produce an alternating charge signal. The signal is subjected to charge conversion, amplification, filtering, and trigger shaping processing on the amplifier, and outputs a square wave voltage pulse signal having the same frequency as the vortex separation frequency. The signal is sent to the local display, and each pulse output by the sensor will represent a volume of the fluid being measured. The total number of pulses output over a period of time will represent the total volume of fluid flowing through the sensor during this time.
   The voltage pulse signal output by the steam flowmeter is sent to the integrated local display instrument. The new micro-power CPU is used to measure the frequency signal output by the vortex sensor, and the flow rate is calculated according to the set density and the vortex flow coefficient. The LCD displays instantaneous flow and cumulative flow. The steam flow meter is not affected by temperature and pressure, and is not easy to block, difficult to card, not easy to scale, high temperature, high pressure, safe and explosion proof, suitable for harsh environments. The steam flowmeter has no movable parts and no void design. The product has no wear and dirt, no mechanical maintenance, long service life, and adopts micro-power high-tech, battery-powered field display flowmeter, which can continuously run two electric machines. More than a year, the integrated design of voltage regulation compensation.
   The current output of the steam flowmeter is electrically isolated, has good common mode interference suppression capability, and displays the flow value and the accumulated flow value. It does not need to be switched in turn. The anti-vibration probe is used to effectively eliminate the influence of external vibration. The circuit adopts the surface mount process. Compact structure and high reliability, using split-type signal converter, the cable length is 10 meters, and the range ratio is 20:1. The overall structure design of the steam flowmeter is reasonable, the dynamic measurement range is wide, and the pressure loss is small. The split vortex flowmeter is made of stainless steel, which can be used for the measurement of corrosive media, on-site liquid crystal display, pulse, 4-20mA output or 485 communication. Can be connected to industrial automation systems.


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