Carbon dioxide continued transport

Although the continuous-countercurrent type of operation has found limited application in the removal of gaseous pollutants from process streams (Tor example, the removal of carbon dioxide and sulfur compounds such as hydrogen sulfide and carbonyl sulfide), by far the most common type of operation presently in use is the fixed-bed adsorber. The relatively high cost of continuously transporting solid particles as required in steady-state operations makes fixed-bed adsorption an attractive, economical alternative. If intermittent or batch operation is practical, a simple one-bed system, cycling alternately between the adsorption and regeneration phases, 1 suffice. 

The major contributors to radiation are soot, carbon dioxide, water vapor, inorganic particulates and other intermediate products whose concentrations depend upon the particular fuel. The presence of solid particles such as ash and carbonaceous material affects the radiation heat transport as they are continuous emitters, absorbers, and scatterers of radiation. Carbonaceous particles tend to be large relative to the wavelength of radiation and have surfaces with high absorptivity. 

The amount of an evolved gas can be determined by a continuous titration method. A carrier gas removes the evolved gas from the furnace chamber and transports it to an aqueous-absorbing solution where it is continuously titrated. The titrant used will depend on the type of evolved gas to be determined. For example, ammonia is titrated with dilute hydrochloric acid, whereas water is determined by the Karl Fischer method. Compounds that can be determined include water, hydrogen chloride, ammonia, sulfur dioxide, carbon dioxide, and chlorine (80). 

Aaron and Tsouris [66] rank membrane separation processes as one of the most promising options. They anticipate advances in ceramic and metallic membrane technology will eventually lead to membrane processes that are more efficient than absorption - the best current option. Favre [67] argues that polymeric membrane technology is competitive today despite its dismissal in most studies. A techno-economic analysis suggests membranes are competitive when carbon dioxide concentration reaches -20% (as found in the effluent from cement and steel factories) and vacuum is used to drive carbon dioxide transport. Although the subject of debate, the potential for membrane technology will continue to attract interest and research effort. 

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