Real-time detection device for ammonia concentration distribution in automobile exhaust based on flat-top laser beams

Abstract

The invention discloses a real-time detection device for ammonia concentration distribution in automobile exhaust based on flat-top laser beams. The device is sequentially provided with a laser emitter, a collimating lens, a flat-top beam shaper, a beam expanding system, a quartz glass tube, a narrow-band optical filter, an imaging lens, a CCD camera and a computer connected with the CCD camera from front to back. The laser emits laser with a specific wavelength, the laser passes through the collimating lens and then enters the flat-top beam shaper, an obtained flat-top laser beam is expandedby the beam expanding system and then traverses the whole quartz glass tube, the narrow-band optical filter and the imaging lens are arranged between the rear end of the quartz glass tube and the CCDcamera, and a tail gas inlet and a tail gas outlet are respectively formed in the tube walls of the two end side surfaces of the quartz glass tube. According to the invention, real-time detection andsingle-point ammonia concentration value detection can be carried out on relative ammonia concentration distribution on the cross section of an automobile exhaust pipeline, and the device can work invarious background noise and high-temperature environments and has a high signal-to-noise ratio.

Description

technical field [0001] The invention relates to an automobile exhaust detection device, in particular to a real-time detection device for ammonia concentration distribution in automobile exhaust based on a flat-top laser beam, which is applicable to the fields of laser technology and automobile engineering. Background technique [0002] Since the 21st century, engine emissions have become the focus of air quality research. NO in engine exhaust gases X The problem of harmful emissions is more serious. Engine emission standards are clearly stipulated at home and abroad. In order to reduce emissions such as nitrogen oxides, due to the technical limitations of the purification system, a common method in China is to use the SCR system to reduce NO X For emissions, urea aqueous solution is selected as the reducing agent. Excessive urea will cause ammonia gas to overflow into the atmosphere. Ammonia is a colorless and irritating gas that can stimulate and corrode human breathing ...

AI Technical Summary

Problems solved by technology

Using the single-point measurement method, when the mixed gas in the pipeline flows through the small hole, the spectrometer is used to analyze and measure the absorption intensity of the target gas and other characteristics. The detected ammonia concentration is only the value of a single point in the pipeline. The ammonia gas in different areas on the cross-section The concentration distribution is uneven, and single-point detection cannot reflect the ammonia distribution of the entire cross-section in real time

Using multiple single-point sampling in the grid format for fitting to realize the detection of ammonia gas distribution in the entire cross-section. Different sampling points will also cause deviations in the measurement data. The distribution of ammonia gas concentration

The technology for measuring the concentration distribution of ammonia gas across the entire cross-section is relatively scarce. If the emission of ammonia gas cannot be accurately measured and prevented when the exhaust gas is discharged from the pipeline, there will be huge hidden dangers to the impact on air quality and human health.

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