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Flow meter application main area introduction

Flow measurement is the science of changing the quality of materials. The law of quality mutual change is the basic law of the development of the relationship between things. Therefore, the measurement object is not limited to the pipeline fluid in the traditional sense. The flow measurement problem is wherever there is a quantitative change. Flow, pressure and temperature are listed as three major test parameters. For a certain fluid, as long as you know these three parameters, you can calculate the energy it has. These three parameters must be detected in the energy conversion measurement. Energy conversion is the basis of all production processes and scientific experiments, so flow is the most widely used for pressure and temperature instruments.
The application of flow measurement technology and instrumentation generally has the following fields.
1. Industrial production process
Flow meter is one of the major types of instruments in process automation instruments and devices. It is widely used in metallurgy, electric power, coal, chemical, petroleum, transportation, construction, textile, food, medicine, agriculture, environmental protection and people's daily life. Such as the national economy, it is an important tool for developing industrial and agricultural production, saving energy, improving product quality, improving economic efficiency and management level, and occupies an important position in the national economy. In process automation instruments and devices, flow meters have two functions: as a test instrument for the process automation control system and a total meter for measuring the quantity of materials. According to statistics, the output value of flow meters accounts for about the total output value of all process automation instruments and devices.
2. Bear source meter
Energy is divided into primary energy (coal, crude oil, coalbed methane, petroleum gas and natural gas), secondary energy (electricity, coke, artificial gas, refined oil, liquefied petroleum gas, steam) and energy-carrying refrigerant (compressed air, oxygen, Nitrogen, hydrogen, water, etc. Energy metering is an important means of scientifically managing energy, achieving energy conservation and reducing consumption, and improving economic efficiency. Flow meters are an important part of energy metering. Water, artificial gas, natural gas, steam and oil use a very large number of flow meters, which are indispensable tools for energy management and economic accounting.
3. Environmental protection engineering
The emissions of flue gas, waste liquid, sewage, etc. are seriously polluted by the atmosphere and water resources, and seriously threaten the human living environment. The country regards sustainable development as a national policy, and environmental protection will be the biggest issue in the 21st century. Air and water pollution must be controlled + management must be strengthened, and management is based on quantitative control of pollution.
China is a country with coal as its main energy source. There are millions of chimneys in the country that continuously emit smoke into the atmosphere. Flue gas emission control is an important project to cure pollution. Each chimney must be equipped with a flue gas analyzer and a flow meter to form a continuous emission monitoring system (cmvrs). The flow measurement of flue gas is very difficult. The difficulty is that the chimney is large in size and irregular in shape, the gas composition is variable, the flow rate range is large (from very low flow rate to high speed), dirt, dust, corrosion, high temperature, no Straight pipe sections and so on.
Waste water and sewage are discharged into rivers and lakes, causing water resources to be destroyed. The already tight water resources are even worse, and emission control management is an urgent task. The flow measurement of waste liquid and sewage is also a difficult measurement. It has the characteristics of dirty media, large caliber, special shape, low pressure head and non-full pipe flow.
With the in-depth development of environmental protection projects, various flowmeters such as electromagnetic flowmeters and vortex flowmeters will continue to be put forward, such as large-scale wastewater recycling equipment, municipal waste treatment equipment, and industrial and mining enterprises. A wide variety of flow meters are required for recycling systems and the like.
4. Transportation
There are five ways of transportation: railway, road, air, water and pipeline transportation. Pipeline transportation has long existed in five ways, but the application is not common. With the outstanding environmental problems, the characteristics of pipeline transportation have attracted people's attention. For example, coal has been transported by rail and water. The pollution environment of loading and unloading and open transportation cannot be ignored. The use of pipeline hydraulic transportation is not only rapid and efficient, but also has a large closed and sanitary environment. advantage. Pipeline materials are: crude oil, natural gas, artificial gas, water, compressed air, coal, grain, cement, minerals, etc. The world's pipeline transportation trunk line has reached 2.3 million kilometers, and China was only 19,000 kilometers in 1996, which is in a backward state. Pipeline transport must be equipped with a flow meter, which is the eye for control, distribution and dispatch, and an essential tool for safety monitoring (monitoring logistics blockages, leaks) and economic accounting.
5. Biotechnology
The 21st century will usher in the century of life sciences, and industries characterized by biotechnology will develop rapidly. There are many substances that need to be monitored and measured in biotechnology, such as blood, urine, liquid medicine, nutrient solution and various gases. The measurement objects are mostly mixed phase flow, pulsating flow, non-Newtonian fluid and micro flow. The development of the instrument is extremely difficult. ,a variety of.
6. science experiment
The flowmeters required for scientific experiments are not only numerous, but also extremely versatile. According to statistics, a large part of the flowmeter 100 is suitable for scientific research. They are not mass-produced and sold in the market. Many scientific research institutions and large enterprises have set up special teams to develop special flowmeters, especially the defense department is more common. . For example, chemical intermediate test, which is an intermediate link in chemical production. A chemical product must be tested by intermediate test from laboratory development to mass production. This test plant is nicknamed the factory that produces experimental data. The accuracy and reliability of the data is the first. One. Various flowmeters such as electromagnetic flowmeters and vortex flowmeters in the test plant are essential instruments. Due to their small size, they are mostly small and microflow measurements. As with the efficiency test of the engine, it needs to detect three parameters: pressure, temperature and flow. It is generally considered that the flow measurement is difficult because the use conditions are special, the flow block in front of the test piece is complicated and there is no straight pipe section arrangement, the fluid composition changes, and the flow is a pulsating flow.
7. Marine meteorology, rivers and lakes
These areas are open flow paths, which are typically measured and then the flow is estimated. The physical principles and hydrodynamics of the flowmeter and flowmeter are common, ‘but the principle and structure of the instrument and the conditions of use vary widely. The International Organization for Standardization (ISO) has a technical committee to develop international standards for such flow meters, and it has been one of the main contents of previous international traffic conferences.
The expansion of flow measurement objects has made it difficult to measure problems.
1) The measured medium is in a flowing state, usually an unsteady flow;
2) There are many kinds of measured media, and the physical and chemical properties are extremely complicated;
3) The measured medium state (pressure, temperature) varies widely;
4) The physical and chemical properties of the measured medium have a great influence on the performance of the instrument;
5) fluid flow characteristics have a great impact on instrument performance;
6) Meter verification equipment is large and complex and expensive.
The difficulty of flow measurement can be divided into two aspects: fluid characteristics and measurement characteristics.
The effects of fluid properties on measurements are grouped into the following categories.
• Dirty fluids are contaminated, deposited, and clogged, such as artificial gas, smoke, sewage, and the like.
· Corrosion flow pipelines are seriously corroded and thus cause dirty flow, and the instrument has high corrosion resistance requirements.
· High parameter flow High temperature, high pressure, vacuum and low temperature extreme conditions - F flow measurement.
• Pulsating flow such as engine, compressor, pump outlet fluid pulsation, oil and gas well jet pulsation, etc.
· Large flow pipe diameter is several meters, liquid flow rate is up to 10AKg/h, and gas flow rate is up to 106kg/h.
• The lower limit of the micro flow rate is extremely low, the liquid is 10 - zks / h, and the gas is 10 - 4kg / h. .
· High viscous flow fluids are extremely high in enthalpy, Reynolds number is very low, and the viscosity can reach several hundred sec.
· Mixed phase flow such as gas-liquid, liquid-solid, gas-solid and gas-liquid solid multiphase flow.
·The flow rate of the measured medium changes greatly when the measured medium is working. The volume measurement method cannot be accurately measured.
· The flow rate of the peristaltic flow is extremely slow, the Raynaud is extremely low, and there are both large and small calibers, such as asphalt and slurry.
The above is only for a certain aspect, and the actual measurement object often has several difficult problems, such as the measurement of the micro-flow rate from the high-temperature and high-corrosion gas, and the measurement of the large-flow of the gas containing the solid dust. With the advancement of technology,

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