tailieunhanh - AIR POLLUTION CONTROL EQUIPMENT SELECTION GUIDE - CHAPTER 2

Sự hấp phụ các thiết bị thiết bị loại Sự hấp phụ các thiết bị bao gồm các phương tiện truyền thông adsorptive, hoặc tĩnh hoặc di động, một tàu chứa khí và các chất gây ô nhiễm của nó được thông qua. Các chất gây ô nhiễm được hấp phụ lên và vào lỗ chân lông trong các phương tiện truyền thông hấp phụ. | chapter 2 Adsorption devices Device type Adsorption devices consist of adsorptive media either static or mobile in a containing vessel through which the gas and its contaminants are passed. The contaminants are adsorbed onto and into pores in the adsorbing media. Typical applications and uses Adsorbers are most commonly used for solvent recovery control of hydrocarbon emissions from storage tanks transfer facilities printing operations and similar processes where volatile hydrocarbons are present. Activated carbon types are also used to control sulfurous odor such as that from sewage treatment plants. Special impregnated carbons are used to chemically react with the contaminant once it is adsorbed thereby extending the carbon life. Where the hydrocarbon has recovery value adsorbers are often used after process vents evaporators or distillation columns to polish the emission down to regulatory limits. They are also used on process vents in lieu of thermal oxidizers. Regenerative adsorbers are generally not used where the contaminant is not economically recoverable or the desorption process has a low yield. For example cases where adding steam to desorb the carbon results in an unusable water mixture tends to make adsorption less attractive. Drum type units are often attached to process tanks to control hydrocarbon breathing or fill venting losses. The gas flow rates are typically low and these drum type units can be applied very economically. Filter type units are used in ventilation systems for hospitals clean rooms auditoriums bus stations loading docks and other environments where adsorbable hydrocarbons may be present. 2002 by CRC Press LLC Operating principles Gas adsorption is the physical capturing of contaminant gas molecules onto or into the surface of a suitable solid adsorbent such as activate carbon zeolite diatomaceous earth clays or other porous media. The gas molecule is physically trapped by the pore openings in the media and accumulates over time .