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Application characteristics of gas mass flowmeter in flue gas measurement system

The wide applicability of gas mass flow meters has made it well received by customers and has its own unique applications in many fields. Today, we talk about the specific application of gas mass flow meters in flue gas measurement systems.
Application background of gas mass flowmeter in flue gas measurement system
Applied to most flue gas measurement systems (CEMS systems) in thermal plants and power plants, the difficulties and problems in measuring flow process analysis are: high temperature, high dust, high moisture, negative pressure and corrosive.
The working conditions are usually: the temperature of the flue gas medium is about 150 °C, and the primary or secondary wind of the thermal power plant is generally 200 ° C, but the individual is also around 400 ° C, the flow rate is generally around 30 m / s; the accuracy is generally required to be 1 About %; dust particles 0~1000mg/m3; pressure measurement range: -70~70mbar.
Under such conditions, the necessary detection accuracy, faster reaction speed, easy installation, easy calibration, and protection against dust, splash, and corrosion are required; there should be a high degree of automation and less maintenance. The amount of work. For these problems, we usually have two instruments to choose from: pitot tube or thermal gas mass flow meter. Let us talk about the application characteristics of the thermal gas mass flow meter.
The gas mass flow meter is a meter that uses the principle of heat conduction to detect the flow rate, that is, the flow rate is measured by the heat exchange relationship between the fluid in the flow and the heat source: the expression is:
P / ΔT = A + B (Q) m, where: A, B is a constant related to the physical properties of the gas.
It can be seen from the formula that the ratio of the heating power to the temperature difference of the heat source can be used to derive the mass flow rate Q. In practical applications, we fix any one of the heating power or temperature difference to measure the mass of the fluid. The former is the constant power method; the latter is the constant temperature difference method.
The gas mass flowmeter uses computer-aided manufacturing techniques, wide range ratio, large diameter, low flow rate, and low pressure loss. Mass flow measurement does not require temperature and pressure compensation, and low flow rate measurement is very sensitive.
In the CEMS system, thermal gas mass flow meters are generally used in foreign countries. Because of its high precision, convenient installation, convenient operation and strong corrosion resistance, it is one of the preferred instruments in the industry.
In China, due to the lack of understanding of the thermal mass flowmeter and the price factor, the application of the thermal mass flowmeter in the CEMS system is not popular. Among many system integrators, due to the poor composition of the medium in the CEMS system, there are often particles, dust, moisture and corrosive components, which are easy to be in the sensing part (the probe part of the thermal flowmeter, the pitot tube is in static pressure, moving The pressed part forms a blockage, causing inaccuracies in the measurement, or even measurement.
Our recommended gas mass flow meters overcome these shortcomings.
For the hot gas mass flowmeter, the probe is extended when the measurement is normal, and the measurement method is the same as that of the normal thermal flowmeter; when the sweep is performed, the probe is extended/retracted, and the probe surface is realized by the wiper block. Clean the dirt. Features: Does not affect the measurement results.
The meter regularly controls the solenoid valve, the solenoid valve controls the air source with a certain pressure, the air source controls the pneumatic device, and moves up and down (or left and right) to drive the scraping block, thereby cleaning the sensing component-probe of the thermal mass flow meter. purpose.
For the hot gas mass flowmeter, during normal measurement, the gas source does not supply gas and does not purify; when purging, the gas is directly blown to the probe through the nozzle, and no measurement is performed at this time. Features: Light weight; easy to maintain; the impact on the measurement results can be ignored.
The hot gas mass flow meter not only has all the characteristics of the thermal flow meter, but also realizes the functions of measuring, sweeping and anti-corrosion, which is deeply loved and trusted by customers.

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