Smoke dust concentration direct-reading monitoring system and method

Abstract

The present invention provides a smoke dust concentration direct-reading monitoring system and method, the monitoring system comprises a speed measuring device, a dilution device and a measuring device, and further comprises a gas supply means, a switching unit and a second flow meter, the gas supply means comprises a pipe, a heating unit, a first flow meter and a valve, the heating unit, the first flow meter and the valve are successively disposed on the pipe, the output end of the valve is connected with the dilution device, the switching unit is used for selectively communicating a smoke inlet of the measuring device with the dilution device or a pipe between the valve the first flow meter, and the second flow meter is disposed on a downstream pipe of the measuring device. The smoke dust concentration direct-reading monitoring system has high reliability, precise monitoring and other advantages.

Description

technical field [0001] The invention relates to flue gas monitoring, in particular to a smoke and dust concentration direct-reading monitoring system and method. Background technique [0002] At present, the domestic atmospheric environment situation is very severe. As the largest coal-consuming household, the contribution of air pollutants emitted by the thermal power industry to fine particles has become a hot spot of public concern. How to accurately measure the concentration of fine particles has become a difficulty in this field. [0003] At present, the commonly used detection methods include light scattering method, β-ray absorption method, light transmission method and so on. [0004] The principle of the light scattering method is: the light beam from the light source is irradiated into a certain space (measurement area) containing the particles to be measured, so that scattering occurs, and the scattered light is converted into an electrical signal by a photoelectr...

AI Technical Summary

Problems solved by technology

[0008] 1. When the temperature of the flue gas is low and there are many liquid droplets in the flue gas, it is difficult to effectively vaporize the liquid droplets only through the whole process of heating. At this time, the liquid droplets will enter the dust measurement unit and affect the dust measurement.

[0009] 2. The whole process of heat tracing is adopted, which requires high heat preservation and heat tracing of the gas circuit. Once there is a cold spot, it is easy to generate condensed water. The condensed water will not only affect the measurement, but also cause corrosion of the pipeline. If it is too long, it will cause airway blockage

[0010] 3. Whole-process heat tracing has high requirements on flow path components, especially globe valves, flow meters, air pumps, etc., which may face the risk of frequent maintenance in field use

[0011] At present, some people also propose to solve the humidity problem in the sampling process of particulate matter by dilution method, such as patent CN104181087A, because the transmission of particulate matter has extremely high requirements on the sampling pipeline, so when designing the dilution system, it is impossible to directly measure the flow rate of flue gas sampling, and The flue gas sampling flow rate is calculated indirectly through the diluted sample gas flow rate and the dilution gas flow rate. Taking a dilution system with a dilution ratio of 1:10 as an example, assuming that the flue gas sampling flow rate is 10L / min, the dilution gas flow rate is 90L / min, and the dilution gas flow rate is 90L / min. The sample gas flow rate is 100L / min, the diluted flow rate and the diluted sample gas flow rate are both measured by a ±1% F.S. The flow error is ±20%, and the corresponding dilution ratio error is ±20%. Therefore, the biggest problem facing the dilution method is the accuracy of the dilution ratio. However, the precise control of the dilution ratio is not mentioned in the above patents.

At the same time, in the patent CN104181087A, the dilution chamber is located outside the flue, and the biggest problem with the dilution chamber being located outside the flue is that when the humidity in the flue gas is high, the adsorption loss of particles is easily generated when condensed water is generated.

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