Sensor locations and noise reduction in high-purity batch distillation control loops

The influence of the sensor locations on the composition control of high-purity batch distillation columns has been investigated. Using concepts of the nonlinear control theory, an input-output linearizing controller was implemented to keep the distillate composition constant at a desired value by varying the reflux ratio. An Extended Kalman Filter was developed to estimate the compositions required in the control algorithm using temperature measurements. In the presence of measurement noise, the control performance depended greatly on the sensor locations. Placing the sensors further from the top stages reduced the detrimental effects of noise but increased the inference error. To achieve accurate composition control, both noise reduction and composition estimate accuracy should be considered in the selection of the sensor locations.671684Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

Sensor locations and noise reduction in high-purity batch distillation control loops

The influence of the sensor locations on the composition control of high-purity batch distillation columns has been investigated. Using concepts of the nonlinear control theory, an input-output linearizing controller was implemented to keep the distillate composition constant at a desired value by varying the reflux ratio. An Extended Kalman Filter was developed to estimate the compositions required in the control algorithm using temperature measurements. In the presence of measurement noise, the control performance depended greatly on the sensor locations. Placing the sensors further from the top stages reduced the detrimental effects of noise but increased the inference error. To achieve accurate composition control, both noise reduction and composition estimate accuracy should be considered in the selection of the sensor locations

Biosorption Of Chromium(vi) Using A Sargassum Sp. Packed-bed Column

Chromium(VI) is present in several industrial wastewaters and it can cause health and environmental hazards above certain concentrations. Equilibrium studies have shown the feasibility of using Sargassum sp. algae for chromium removal from aqueous solutions by biosorption. However, for the design and operation of chromium biosorption processes, dynamic flow studies are required. The objective of the study was to examine chromium(VI) removal from an aqueous solution using a packed-bed column with Sargassum sp. algae as a biosorbent. The dynamic behavior of the biosorption column was investigated through experiments and the influence of operating conditions, such as initial chromium concentration, flow rate and amount of biosorbent, on the column removal capacity have been analyzed using the factorial design methodology. The capacity of removal obtained at optimum conditions was 19.06 mg of metal/g biosorbent. © 2007 Elsevier Ltd. All rights reserved.99830943099Boney, A.D., (1966) A Biology of Marine Algae, , Hutchinson Educational Ltd., New York p. 216Cossich, E.S., Tavares, C.R.G., Ravagnani, T.M.K., Biosorption of chromium(III) by Sargassum sp. biomass (2002) Electronic Journal of Biotechnology, 5 (2), pp. 133-140Davis, T.A., Volesky, B., Mucci, A., A review of the biochemistry of heavy metal biosorption by brown algae (2003) Water Research, 37, pp. 4311-4330Kartal, S.N., Imamura, Y., Removal of copper, chromium, and arsenic from CCA-treated wood onto chitin and chitosan (2005) Bioresource Technology, 96, pp. 389-392Kratochvil, D., Pimentel, P., Volesky, B., Removal of trivalent and hexavalent chromium by seaweed biosorbent (1998) Environmental Science and Technology, 32, pp. 2693-2698Lalvani, S.B., Wiltowski, T., Hubner, A., Weston, A., Mandich, N., Removal of hexavalent chromium and metal cations by a selective and novel carbon adsorbent (1998) Carbon, 36, pp. 1219-1226Melo, J.S., D'Souza, S.F., Removal of chromium by mucilaginous seeds of Ocimum basilicum (2004) Bioresource Technology, 92, pp. 151-155Nasernejad, B., Zadeh, T.E., Pour, B.B., Bygi, M.E., Zamani, A., Comparison for biosorption modeling of heavy metals (Cr(III), Cu(II), Zn(II)) adsorption from wastewater by carrot residues (2005) Process Biochemistry, 40, pp. 1319-1322Romero-González, J., Peralta-Videa, J.R., Rodríguez, E., Ramirez, S.L., Gardea-Torresdey, J.L., Determination of thermodynamic parameters of Cr(VI) adsorption from aqueous solution onto Agave lechuguilla biomass (2005) Journal of Chemical Thermodynamics, 37, pp. 347-351Volesky, B., Detoxification of metal-bearing effluents: biosorption for the next century (2001) Hydrometallurgy, 59, pp. 203-216Volesky, B., Weber, J., Park, J.M., Continuous-flow metal biosorption in a regenerable Sargassum column (2003) Water Research., 37, pp. 297-30