Quasi constant weight weighing apparatus and method for monitoring mass concentration of atmospheric particulates by utilizing oscillation balance method

Abstract

The invention discloses a quasi constant weight weighing apparatus and method for monitoring the mass concentration of atmospheric particulates by utilizing an oscillation balance method. The method comprises the steps of: joining a three-way pipe, an electric ball valve and a particulate filter between a measured sample transporting pipe and a measured sample heating pipe of the traditional apparatus for monitoring particulate concentration by utilizing the oscillation balance method; changing the original process of inputting the measured samples to a filter membrane weighing part continuously into a process of intercepting the measured sample particulates by a filter membrane and a process of keeping a constant weight of the filter membrane respectively and intermittently, according to a specified period. According to the invention, the particulate concentration measurement with the constant weight weighing process of the filter membrane can be realized by the apparatus for monitoring the concentration of particulates by utilizing the oscillation balance method, the comparability with the standard gravimetric method is effectively solved, and the monitoring result equivalent to the standard gravimetric method requiring a constant weight of the filter membrane is obtained, and the quasi constant weight weighing apparatus and the method are particularly suitable for the rainy and misty days, the sizzard and the like with relative higher humidity.

Description

Technical field [0001] The invention relates to the technical field of testing and analysis, in particular to a quasi-constant weight weighing device and method that adopts an oscillatory balance method in monitoring the mass concentration of atmospheric particles. Background technique [0002] At present, in order to cope with and solve the environmental pollution problems caused by industrial production and human lifestyles, especially the serious haze problem, it is necessary to continuously, accurately and extensively monitor the mass concentration of atmospheric particulate matter; The large number of automatic ambient air monitoring stations with complex systems all regard atmospheric particulate matter concentration as the main monitoring item. [0003] Different from gas composition analysis, the mass concentration of atmospheric particulate matter is equal to the ratio of the total mass of all non-gaseous and non-liquid substances in the collected sample to the standard st...

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Problems solved by technology

[0015] However, compared with the standard gravimetric method for monitoring the mass concentration of atmospheric particulate matter, the above-mentioned automatic monitoring instrument for the mass concentration of atmospheric particulate matter by the oscillating balance method lacks the operation process of "weighing after being placed in a constant temperature (dry) balance room to reach a constant weight".

The evaporable substances that are intercepted on the filter membrane during the sampling process, such as the moisture attached to the particles, will be "baked" by the temperature of the filter membrane weighing mechanism (set to prevent the frequency drift of the quartz oscillator element) higher than the air temperature. Gradual evaporation will cause interference to the measurement of its cumulative load mass, resulting in errors in the particle concentration monitoring data; especially in the case of high atmospheric relative humidity levels such as rain, fog, and hot flashes, the particle concentration will often be lower than 0 (negative value) abnormal data

[0016] The existing vibrating balance method particle concentration monitoring instrument cannot measure the filter membrane after constant weight (drying) in its structure.

Sampling must be stopped because of constant weight, and if there is no flow rate of the sample to be measured, the load mass of the vibrating balance will change due to changes in dynamic indicators such as the disappearance of airflow resistance, and its working temperature will also change due to the disappearance of convection, resulting in serious shocks The frequency drift of the balance makes it impossible to detect the particle concentration normally

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