Elimination Of Siloxanes By Adsorption ProcessAs A Way Of Upgrading Biogas
Biogas is increasingly being investigated as a source of renewable energy, however its utilisation requires an improvement of its quality. Certain biogases contain compounds called siloxanes; these compounds are the origin of some problems when using biogas. At high temperatures siloxanes are transformed to silicate oxides which can damage equipment (i.e. engines corrosion, the clogging of fuel cell membranes.). This paper provides details of the research done in the treatment of siloxane by adsorption process of adsorption. Different porous materials were studied in order to evaluate adsorption capacities. Influences of humidity and temperature on the mass transfer were evaluated. Moreover, reactors were filled with a mixture of methane and carbon dioxide (principal compounds on the biogas) in order to evaluate the impact of the gas composition in the adsorption capacities. Finally the capacity of adsorption is also evaluated in the presence of an organic volatile compound (VOC). Activated carbon cloth was chosen to continue with the experiences realised for the adsorption – desorption process. This porous material has shown good adsorption capacities. Furthermore, desorption process can be performed in situ and their implementation in industrial process is more easy. Adsorption-desorption cycles were performed and the possibilities of the material regeneration evaluated. Joule effect was employed in the desorption process in order to reduce the duration of regeneration. First cycles have been accomplished. Results are promising, even if the operational conditions of the process must be optimised.
Adsorption of organic compounds onto activated carbon
Abstract Adsorption isotherms of acetone, propionaldehyde, methylisobutylketone and sucrose from aqueous solutions onto granular activated carbon have been determined. Multi-solute data have been compared with the theoretical prediction obtained from ideal adsorbed solution model. The agreement between calculated and observed results is satisfactory. Only the system sucrosemethylisobutylketone shows significant deviation between experimental and predicted values. Therefore the model can be successfully utilized in design of activated carbon units.
Control of phenol in biological reactors by addition of powdered activated carbon
Abstract A biological reactor containing a pure culture of E. coli was subjected to a variety of feed upsets involving phenol with powdered activated carbon applied as a control mechanism. The amount and rate of addition of the carbon was varied to evaluate the effectiveness of this strategy for maintaining the effluent quality. It was found that the carbon addition greatly reduced the magnitude of concentration transients and permitted operation with an input phenol concentration above 1000 mg 1−1.