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Abstract: This paper discusses the progress of flow measurement instruments in a multi-parameter measurement, such as the popularity of low-cost development trends as well as several flow meter applications.
Keywords: Flow Meter Application Development Trends Progress
First, the development trend
1, the flow sensor (trancduccer) multi-parameter measurement
Flow rate detection element or flow sensing element (sensor) in addition to experience flow, but also may experience other variables, and thus give rise to other functions, simplify the process detection system, reducing the number of instruments and the connecting line, to reduce costs. Reducing the flow conduit openings reduces potential leak failures.
a. Rivoli mass flowmeter
b. Electromagnetic Flowmeter
Non-full pipe electromagnetic flowmeter to measure the average velocity in the same time must also measure the height of liquid in the tube. Use both forward and reverse field winding in series, respectively, to produce a flow rate signal potential of two different magnetic field strength and the magnetic field distribution was measured, and the ratio between the level of the two potential function of a certain height.
c. Vortex Flowmeter
Vortex vortex shedder vortex separation frequency f is proportional to the velocity v (f = k1 v, k1 is a coefficient), while feelings and ρv2 proportional lift F (F = k2ρv2, ρ is the fluid density, k2 is a coefficient) . To f divided by F, multiply the flow in the area A, series can be obtained by mass flow qm, namely
qm = (F / f) A = (k2ρv2 / k1v) A = kρvA
Where k-- meter factor k = k2 / k2.
d. ultrasonic flowmeter
Mass flowmeter ultrasonic transit time method on the basis of trying to ultrasonic volumetric flowmeter on the use of ultrasound in the second parameter measured liquid acoustic impedance and density, mass flow rate obtained after calculation.
2, equipped with the second parameter sensing element (or an independent second parameter sensor) or other combinations of measuring mass flow parameter
a. Coriolis mass flowmeters equipped with differential pressure transmitter measuring the viscosity
b. Vortex is equipped with differential pressure transmitter measuring mass flow
c. the gas volumetric flow meter integral pressure / temperature sensing element measuring mass flow
d. Electromagnetic Flowmeter interior temperature sensing element temperature corrected volume
Japan's recent push Yamatake electromagnetic flowmeter market, there is a resistance temperature detector electrodes built pt pieces to solve such problems.
3, the pressure differential pressure instrument shedder and differential pressure transmitter integrated transformer
The differential pressure transmitter directly with nozzles or the average rate throttling device fitted together, is omitted in the field of cloth impulse piping project to improve the dynamic characteristics, reduce maintenance and failure rates, lower home early and operating costs. According to Japan from 1996 to 1997 between the new survey of four plants, the use of nearly 400 differential pressure flow meter, integrated direct-mount instrument accounted for one-third.
4, the development of universal instrument
Moderately reduce the measurement accuracy of performance, general-purpose function to cancel the original selection function to simplify instrumentation components, designed to narrow the scope of application of the instrument, thereby reducing the price to expand the user plane.
a. Coriolis mass flowmeter universal design
Coriolis mass flow decrease accuracy (scale error is reduced from about ± 0.2% to ± 0.5%), reduced functionality, the actual popular instrument.
b. Electromagnetic flowmeters process industry shift from residential civilian areas
Reduce electromagnetic flowmeter measurement accuracy and other properties, such as position in the basic error ± 2%, is designed to have a water meter electromagnetic water meter features. In Japan, this type of electromagnetic water meter water meter has been incorporated into the Japanese standard.
c. Ultrasonic domestic gas meter
Low natural gas prices to foreign civilian measurement ultrasonic flowmeter scale production. The average price is about the process of industrial ultrasonic flowmeter average price of 1/30.
Second, the application progress
Mature instrumentation certain restricted areas after a breakthrough technology, the development of improved instrumentation adapted so that there is rapid development in the field to discuss the progress of several flow meter applications below.
An ultrasonic flowmeter
In recent years, ultrasonic flowmeters used in gas (including steam), storage transfer (custody transfer, often referred to as CT) and finance and trade accounts, residential natural gas consumption metering great progress in three areas.
a. Gas Applications
The current foreign energy development, rapid development of natural gas than oil, and promote the development of the past slow development of gas ultrasonic flowmeter. It is estimated that industrial ultrasonic flowmeter, currently nearly 15% for gas.
In recent years also saw at least three factories abroad to market used in steam ultrasonic flowmeter, stick with a transfer speed of sound signals to bounce away from the steam transducer can measure up to 480 ℃ of superheated steam.
b. into the storage and transfer of finance and trade accounting applications
Multi-channel ultrasonic flowmeter measurement (4 to 8 channels) technology and a short tube flow sensor design, and real-calibration, significantly improved measurement accuracy, precision instrument grade liquids up to 0.15, the universal gas meter to 0.5. There are inevitable in the future will gradually replace the meter moving parts.
1999 Beijing pipelines already tops in Beijing with a high-pressure natural gas ultrasonic flowmeter, some with the original orifice differential pressure flowmeter contrast, demonstrating its superior performance, get all the recognition.
c. enter domestic consumption of natural gas metering applications
90 In mid foreign domestic gas meter ultrasonic applications has reached more than 150 years to replace diaphragm gas meter scale. It is estimated that worldwide sales in recent years has been close to 40 million units / year.
2, electromagnetic flowmeter
a. non-full pipe electromagnetic flowmeter
Conventional electromagnetic flowmeter can measure the full pipe liquid flow, non-filled pipes electromagnetic flowmeter is applied to a surface water discharge areas of the natural flow freely, and to improve the measurement accuracy in the field. The traditional non-full pipe flow or open channel flow flow error is reduced from ± (3 ~ 5)% FS to ± (1 ~ 2)% FS.
b. Measuring more low liquid permeability
2 ~ 3 orders of magnitude lower than conventional liquid now measurable electromagnetic flowmeter conductivity threshold, can not be measured as previously glycerin, ethylene glycol and the like. In addition, this class of instrument noise is almost non-existent raw slurry and flow noise, it does not produce noise effect electrode formed on the surface. Surface covering oil and other non-conductive layer or junction thin insulating layer lining the scale does not affect the measurement.
c. Low power consumption and wire magnetic flowmeter rapid development
Wire circuit without additional external excitation, only 4mADC current power required to provide instrumentation, usually only tens of milliwatts. Low-power electromagnetic flowmeter makes it possible to employ batteries or solar cells, more convenient place for the electromagnetic flowmeter installed without mains supply.
d. D (direction) electromagnetic flow meter and multi-point measurement insertion electromagnetic flowmeter
Placed on the outside of the ship hull speed electromagnetic instrument is the prototype of the plug-in electromagnetic flowmeter. Later, there is a greater insertion electromagnetic flowmeter in medium and large development pipeline, there are open channels, known as electromagnetic flow meter (electromagnetic current meter). But in a stream or river water conservancy test model not only to measure the flow rate but also know the direction of the flow rate. Dimensional electromagnetic flow meter flow shorthand known as vectors, the electromagnetic flow meter race can enter the hydrologic test applications.
Also insertion electromagnetic flowmeter reference design ideas uniform tube inserted rod set multiple sets of electromagnetic flow measurement unit, to improve measurement accuracy, the insertion electromagnetic flow meter in the bassoon is in a good position by the application.
3, the thermal mass flowmeter
Thermal mass flow meter in the past mainly distributed heat, used in low flow measurement of gas, more used in the semiconductor industry, heat treatment furnace, analytical instruments, such as hydrogen, oxygen, ammonia and other flow measurement and control, and valve leakage rate measured during the manufacturing process and so on. In recent years, the heat dissipation effects of foreign invasion and plug-in thermal flow meter application and environmental protection and process industries and medium-sized pipeline is developing rapidly. Radial segment arrangement consisting of multiple sets of detector elements detecting lever, insert more ways to apply to HVAC (heating ventilation and air conditioning) and medium-sized pipeline project; also used in boilers and large pipes into the wind monitoring SO2 and NOX exhaust flue emissions.
Tiny liquid thermal mass flowmeter, although more than 20 years of history, but in the industrial application until recent years that it has developed rapidly, and now has several factories producing a variety of models of heat distributed thermal flowmeter market. Currently mainly used in chemical, petrochemical, food and other process industries experimental devices. For example: liquid ratio constant flow ratio control system, gas injection process flow measurement and control.
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