Cai Wu chang (Shanghai Guanghua Yi Biaochang Shanghai 200233)

Abstract: This article discusses flow measurement instruments in the multi-parameter measurements, such as the popularization of low-cost development trends and the flow meter several applications in progress.

Key words: flow instrumentation development trend of progress

First, the development trend

1, flow sensors (trancduccer) of multi-parameter measurement
Detection of components or traffic flow sensor (sensor) in addition to feelings of traffic, may also be feelings of other variables, and thus derived from other functions, which simplifies the process of detection systems, and reduce the number of instruments and connecting pipelines, and reduce costs. Opening the pipeline flow to reduce leakage to reduce the potential failure.
a. Rivoli mass flowmeter



b. electromagnetic flowmeter

Non-filled pipes in the electromagnetic flowmeter measurement of the average velocity of the measurement must also be highly liquid. Use two field winding forward and reverse series connection, respectively, have two different magnetic field intensity and distribution of the magnetic field measured the velocity signal potential, both the ratio between potential and high level have a certain function.


c. Vortex Flowmeter

Vortex Flowmeter vortex in the vortex of separation frequency f proportional to the velocityvf= k1 vk1 for the coefficientAt the same time feeling and v2 directly proportional to lift F (F = k2 v2, for the fluid density, k2 for the coefficient). To f divided by F, by circulation in the area A, can be obtained for mass flow qm, that is,
qm=F/fA=k2v2/k1vA=kvA
k - Instrumentation coefficient k = k2/k2.

d. Ultrasonic Flowmeter

Ultrasonic Flowmeter the quality of time trying to spread ultrasonic flowmeter on the basis of volume, measured in the use of ultrasound parameters of the second liquid acoustic impedance and density of calculus after a mass flow.

2, allocated by the second parameter detection devices (or independent of the second parameter sensors) measuring the quality of portfolio flows or other parameters
a. Coriolis mass flow meter used with differential pressure transmitter measurement viscosity
b. vortex flowmeter with differential pressure transmitter by measuring mass flow
c. volume of gas flow meter interior pressure / temperature sensor measuring mass flow
d. electromagnetic flowmeter interior temperature detection devices that volume temperature
Japan-Hill recently to market the electromagnetic flowmeter, there is built-pt electrode temperature detection of resistance to solve such problems.

3, the pressure differential in the instrument of integration and differential pressure transmitter PSA
Pressure transmitter will be directly with the nozzle, and other devices or cutting expenditure are loaded with speed control, omitted the cloth at the scene with pressure pipeline project to improve the dynamic characteristics, reduce maintenance and failure rate, lower costs and home early running costs. According to Japan from 1996 to 1997, four new factories survey, used by nearly 400 Pressure-flow meters, the integration of instruments installed directly accounts for one-third.

4, the development of universal-type instrument

Moderately lower performance such as precision measurement, for the abolition of the common functions to select features to simplify the instrumentation components, designed to narrow the scope of application of the instrument, thus lowering prices to expand users face.

a. Coriolis mass flow meter design universal type
Coriolis mass flow decreased accuracy (error range from 0.2% down to around 0.5%), reduced function, the actual popular type instrument.

b. electromagnetic flowmeter from the process industries to civilian residential areas
Reduce electromagnetic flowmeter performance such as precision measurement, such as basic error in the positioning 2%, designed to have the characteristics of the electromagnetic meter of water meters. In Japan such electromagnetic meter of water meters have been included in the Japanese standard.

c. ultrasound domestic gas meter
Foreign civilian low prices of natural gas measurement ultrasonic flowmeter to form the scale of production. The average price of about processes for industrial use ultrasonic flowmeter average price of 1 / 30.


Second, application of

Instruments on the maturity of a restricted area, the technical breakthrough, developed a line of modified instruments, in the field have made rapid development, discussed below several Flowmeters progress in the area of application.
1, ultrasonic flowmeter
In recent years, ultrasonic flowmeter for gas (including steam), storage transfer (custody transfer, often referred to CT) and the Finance and Trade accounting, civilian residential natural gas consumption measurement greater progress in three areas.

a. gas application
At present foreign energy development, the rapid development of natural gas than oil, and promote the slow development of gas over the past ultrasonic flowmeter development. Some people estimate for industrial use ultrasonic flowmeter, the current nearly 15 percent for gas.
In recent years, also saw at least three foreign factories to market the application of ultrasonic flowmeter steam, with a transmission speed of sound signals to the rods away from the steam of the ultrasound transducer, can be measured as high as 480 the superheated steam.

b. into the storage and transfer of Finance and Trade accounting applications
Ultrasonic Flowmeter a multi-channel measurement (4 to 8-channel) short of technical and structural design flow sensors and real-calibration, measurement accuracy of the sharp increase, the liquid used precision instrument rating is as high as 0.15, gas use Instrumentation is generally 0.5. The future will inevitably be gradually replaced with moving parts of the instrument.
1999 in Beijing, Beijing has high-pressure gas pipeline tops ultrasonic flowmeter, and some original orifice Pressure Meter contrast, has demonstrated its superior performance, the recognition from all parties.

c. enter domestic consumption of natural gas measurement applications
90 medium-term foreign ultrasound household gas meter has reached more than 150 applications to replace the membrane gas meter on a larger scale. It was estimated worldwide sales in recent years has been close to 40 million / year.

2, electromagnetic flowmeter

a. Non-filled pipes electromagnetic flowmeter
Only the traditional electromagnetic flowmeter for measuring the flow of liquid-filled pipes electromagnetic flowmeter for a free flow of natural surface water discharge areas, and enhance the areas of measurement accuracy. Non-traditional channel for the flow or traffic flow from the error of (3 ~ 5)% FS reduced to (1 ~ 2)% FS.

b. measuring more low conductivity of liquid
Now measurable than traditional electromagnetic flowmeter conductivity threshold of two to three low-volume liquid, such as before can not be measured glycerin, ethylene glycol, and so on. In addition, this instrument is almost non-existent health and mobility serous Noise Noise, would not have formed the electrode surface effect of noise. Lining the inner surface covering oil, and other non-conductive thin insulating layer or end of the scale would not affect measurements.

c. low power consumption and second-tier system is faster development of electromagnetic flowmeter
Two-do not need another external excitation circuit, only 4 mADC current instruments provide the necessary power, usually only tens of milliwatts. Low-power electromagnetic flowmeter so that may have batteries or solar cells, will be more convenient to electromagnetic flowmeter with no electricity supply to the premises.

d. Two-dimensional (direction) of the electromagnetic flow measurement points and more plug-in electromagnetic flowmeter
Placed in the external hull of the ship speed electromagnetic instrument is inserted into the embryonic form of electromagnetic flowmeter. Later, plug-in large and medium-sized electromagnetic flowmeter in the pipeline have greater development, but also for the channel, known as the velocity of electromagnetic (electromagnetic current meter). But in the river or stream water test model not only to measure velocity would also like to know the direction of flow. 2-D vector Electromagnetic also known as the flow velocity of shorthand, so that electromagnetic flow meters hydrologic people can enter the pilot applications.
In addition electromagnetic flowmeter also plug-in the light of the uniform of the design, insert the rod in the home several sets of electromagnetic flow measurement unit, improve the measurement accuracy, insert the electromagnetic flow is the application of the Daguan in a good position.
3, thermal mass flowmeters

hermal mass flowmeter of the past is distributed, used in small gas flow measurement, and more for the semiconductor industry, heat treatment furnace, analytical instruments, such as hydrogen, oxygen, ammonia, and other flow measurement and control, and manufacturing process of valve leakage Volume, and so on. In recent years, foreign heat dissipation of the effect of invasive and plug-in application of heat flow meter industrial processes and environmental protection and the rapid development of large and medium-sized channels. Radial with multiple sub-components of the test-testing, more used to insert the way HVAC (heating ventilation and air conditioning) large and medium-sized project pipeline and also used in the boiler pipes into the wind and stack emissions monitoring of SO2 and NOX Total emissions.
Quality of tiny liquid flowmeter although there more than 20 years of history, but in the industrial application only until the rapid development in recent years, now has several factories producing various types of distributed heat flow meter into the market. At present mainly used in chemical, petrochemical, food and other industrial processes experimental device. For example: liquid ratio system will flow ratio control, liquefied petroleum gas injected into the process of flow measurement and control.