Gaseous pollutants absorption

In most processes involving the absorption of a gaseous pollutant from an effluent gas stream, the gas stream is the processed fluid hence, its inlet condition (flow rate, composition, and temperature) are usually known. The temperature and composition of the inlet liq-... 

Of the three categories, the packed column is by far the most commonly used for the absorption of gaseous pollutants. Miscellaneous gas-absorption equipment could include acid gas scrubbers that are commonly classified as either wet or diy. In wet scrubber systems, the absorption tower uses a hme-based sorbent liquor that reacts with the acid gases to form a wet/solid by-product. Diy scrubbers can be grouped into three catagories (1) spray diyers (2) circulating spray diyers and (3) dry injection. Each of these systems yields a diy product that can be captured with a fabric filter baghouse downstream and... 

The removal of one or more components from a gas mixture by absorption is probably the most important and familiar operation in the control of gaseous pollutant emissions. Though most often used for the control of inorganic gases, absorption can also be used for recovery of organic compounds. Absorption in-... 

One way to control gaseous pollutants like SO2 and SO3 is to remove the gases from fuel exhaust systems by absorption into a liquid solution or by adsorption onto a solid material. Absorption involves dissolving the gas in a liquid while adsorption is a surface phenomenon. In each case, a subsequent chemical reaction can occur to further trap the pollutant. Lime and limestone are two solid materials that effectively attract sulfur dioxide gas to their surfaces. The ensuing chemical reaction converts the gaseous pollutant to a solid nontoxic substance that can be collected and disposed or used in another industry. 

Werle, P., R. Muecke, and F. Slemr, Development of a Prototype IR-FM Absorption Spectrometer Design Criteria and System Performance, in Monitoring of Gaseous Pollutants by Tunable Diode Lasers (R. Grisar, H. Boettner, M. Tacke and G. Restelli, Eds.), pp. 169-182, Kluwer Academic, Dordrecht, The Netherlands, 1992. 

Light absorption at specific wavelengths is another principle often employed for the online measurement of gaseous pollutants. For example, the absorption of 03 in the ultraviolet at 254 nm can be used, though this experiences cross sensitivity to S02 and PAHs, and C02 in the infrared at 4.26 pm (2,350 cm-1), which has little cross sensitivity to other gases. The most common C-H absorption bands are in the range of 3.33-3.57 pm (2,800-3,000 cm-1). 

On the other hand, gaseous pollutant control can be carried out by contacting the gaseous stream with a component (either solid, liquid, or gaseous) that is capable of selectively removing one or more pollutants. One of the most common techniques used for the removal of gaseous pollutants is absorption, mainly for removal of... 

NOXIOUS GAS REMOVAL. Gaseous pollutants can be removed from air streams either by absorption, adsorption, condensation, or incineration. A list of typical gaseous pollutants that can be treated with these four methods is given in Table 9. Generally, condensation is not utilized as a method for removing a solvent vapor from air or other carrier gas unless the concentration of the solvent in the gas is high and the solvent is worth recovery. Since condensation cannot remove all of the solvent, it can only be used to reduce the solvent concentration in the carrier gas. 

Solvent selection for use in an absorption column for gaseous pollutant removal should be based upon the following criteria ... 

The absorption or fixation of solid pollutants and aerosols is generally accomplished on paper, membrane (nitrocellulose), polystyrene or glass-fibre filters. It should be noted that aerosols may also be sampled directly into absorption solutions (similarly as when sampling gaseous pollutants) and with the help of electrostatic precipitators however, these methods are infrequently used in practice. Particular types of filters are selected depending on the type of the pollutants to be determined. The filter quality is considered from the standpoint of the pore size, efficiency of capture. 

An extensive literature exists on the measurement of primary gaseous pollutants via their intrinsic absorption using optical Hbers [28]. Typical examples include methane [29], NO2 [30], SO2 [31], propane [32], and fluorinated compounds [33]. The whole wavelength range that is compatible with standard flbers has been covered. Table 18-1 lists the species that have been studied so far, together with the wavelengths of operation. 

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