Method and equipment for calibrating dust-measuring instrument

Abstract

The invention relates to a method and equipment for calibrating a dust-measuring instrument. Weighed test dust is dispersed and then fed into a self-circulation system with stable gas flow, so that flowing standard dust-containing gas with stable concentration is prepared; and standard dust-containing gas with different concentrations can be prepared just by changing the quantity of the fed dust, and the dust-measuring instrument to be calibrated can be rapidly and correctly calibrated. The equipment comprises the dust-measuring instrument (1), a self-circulation pipeline (2), a dust generating device (3), a flow measuring device (4), a flow velocity and pressure adjusting valve (5), a circulating fan (6), an air filter (7), an air heater (8), a switch valve, a dust collector (12), an exhaust fan (13), connecting pipelines between all devices, and the like. Compared with the prior art, the method and the equipment can rapidly and correctly calibrate the dust-measuring instrument, thereby greatly reducing the error of the dust-measuring instrument and enabling the measurement data of the dust-measuring instrument to be more real and reliable.

Description

technical field [0001] The invention relates to the fields of instrument manufacturing and environmental protection, in particular to a calibration method and equipment for a dust measuring instrument. Background technique [0002] The gas dust concentration is the dust mass in unit gas volume. There are currently two methods for measuring the dust concentration in various indoor air, outdoor atmosphere and flue gas: first, the direct method is the weighing method. Filter the dusty gas, then weigh the filter cartridge or filter paper, and finally calculate the dust concentration of the gas based on the measured gas flow. Second, the indirect method, light scattering method and electrostatic induction method are commonly used at present. The light scattering method is to emit laser light into the dust-containing gas, and determine the dust concentration of the gas according to the change of the received light intensity; the electrostatic induction method is to generate an i...

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Problems solved by technology

[0003] The sampling time of the direct method varies according to the level of dust concentration in the gas, and generally takes 15 to 20 minutes, that is, the dust concentration of the gas measured by the direct method is the average value of the sampling time. Although the data is accurate and reliable, continuous measurement cannot be achieved

The indirect method can realize the continuous measurement of gas dust concentration, but the measurement error is greatly increased because it relies on the direct method for calibration and arithmetic mean processing data, according to the environmental protection industry standard of the People's Republic of China with the standard number HJ / T75-2007 "Technical Specifications for Continuous Monitoring of Flue Gas Emissions from Stationary Pollution Sources (Trial)" stipulates that the acceptance of the continuous monitoring system of flue gas emissions from fixed pollution sources adopts the above-mentioned direct method, and its assessment index is that the relative error does not exceed ±30%. Obviously, this error is too large, but Restricted by existing technical methods, it can only be stipulated in this way

[0004] It can be seen from the above situation that although the existing dust measuring instrument can realize continuous measurement, due to the limitation of the calibration method, the allowable error of the dust measuring instrument is too large, which seriously affects its measurement accuracy

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