High-speed low-temperature gas analyzer for pulsed emissions of liquefied natural gas into the atmosphere based on immersion diode optocouplers

Abstract

A low-temperature infrared optical gas analyzer based on immersion diode optocouplers with a speed of less than 0.03 s has been developed to detect pulsed emissions into the atmosphere of explosive mixtures of liquefied natural gas and alkanes with air at a temperature of more than 150 K with the transfer of digitized data to a remote server. The design is described and its characteristics are given in the process of analyzing mixtures of air with pure methane, ethane, propane and LNG of various compositions. It is shown that the speed and operating temperature range of the gas analyzer exceed the parameters of foreign and domestic analogues for monitoring man-made LNG emissions into the atmosphere. Keywords: alkanes, speed, infrared optical gas analyzer, pulse emissions, immersion diode optocouplers, liquefied natural gas.

The high-speed two-channel analyzer of optically dense aerosol emissions based on diode optocouplers with a wavelength of 0.65 and 3.4 microns

“…Express analysis of optically dense aerosol emissions into the atmosphere and the development of explosivetype generators for the rapid creation of large-scale barriers of fine droplets on the path of the spread of toxic and combustible clouds is of interest for industrial safety systems of objects, production and storage of fuel liquids (kerosene, gasoline, fuel oil, diesel fuel (DF), oil, heptyl, alcohol, etc.). During technogenic fuel emissions in the form of jets and spills on the ground there is a high probability of the formation of explosive and flammable fuel-air mixtures (FAM) with a volume of more than 10 4 m 3 [1][2][3][4][5].…”

“…The analysis of FAM emissions is quite complicated, since it is necessary to measure the fluctuating characteristics of particles with data transfer to a remote server, and devices for their scanning must have a response τ ≤ 0.1 s, operate at gas-droplet flow rates up to hundreds of meters per second, and be resistant to impulse action of excessive gas pressure (> 10 5 Pa) [1][2][3][4][5][6][7][8][9][10].…”

“…It is known that single-channel and two-channel laser analyzers of aerosol flows (optocouplers) with an inertial droplet separator with a diameter of d > 15−20 µm and a radiation wavelength of λ = 0.6−0.7 µm were designed [3,4]. These devices make it possible to measure with τ ≤ 0.05 s the dynamic values of the optical density D = lg(I 0 /I) ≤ 3.5 and the specific surface concentration of droplets S = π d 2 N (m 2 /m 3 ), as well as the value of their root-mean-square deviation at a volume concentration of droplets less than 0.1% vol.…”

“…Here I 0 and Iradiation intensities without and in the presence of FAMs, respectively, in the optical channel of the optocoupler; d 2 0.5root-mean-square diameter of droplet with differential size distribution f (d); count concentration N [1][2][3][4][5]. In the case of common lognormal distribution of droplets by diameters, the value d 2 = d 2 exp(ln 2 σ ), where darithmetic mean droplet diameter and σstandard geometrical deviation [5].…”

“…In the case of a monodisperse particles flow K = Nβ(m)πd 2 /4, where β(m) is the attenuation coefficient of radiation by droplet from the value of the Mie scattering parameter m = πd/λ [5][6][7][8]. A generalization for polydisperse droplets in the approximation that the contribution from each of the droplet groups to K is additive has the form [3][4][5]7]:…”