NOPR Collection:

ANN controller trained with steady state input-output data for a heat exchanger

Tue, 01 May 2001 00:00:00 GMT

Title: ANN controller trained with steady state input-output data for a heat exchanger Authors: Dasgupta, M S; Menon, G B; Gupta, R K Abstract: This paper discusses the design and implementation of an Artificial Neural Network (ANN) based adaptive controller for a heat exchanger. The control strategy chosen is that of explicit nonlinear model predictive control. The nonlinear inverse model of the plant is identified from steady state input-output data by off-line training of a multilayered neural network through error back propagation. For performance enhancement, manipulation of training data and on-line parameter updating are tried. Single pass of derivative of error measure across the plant, on-line gave an excellent performance for regulatory as well as servo problem. The proposed cont roller is found to be successful over a wide operating range. The results are compared with that of an optimized PID controller. Page(s): 227-234

Acid cleaning operation for a natural circulation high pressure drum boiler unit of a thermal power station

Tue, 01 May 2001 00:00:00 GMT

Title: Acid cleaning operation for a natural circulation high pressure drum boiler unit of a thermal power station Authors: Sohail, M Azad; Mustafa, A Ismail Abstract: Two-stage acid cleaning (TSAC) operation has been employed and investigated to clean up undesired impurities (deposit) in boiler water wall tubes (BWWT), boiler drum, super heater, economizer, feed water lines, live steam lines, hot reheat lines, cold reheat lines, dearator, collectors, headers for a natural circulation high pressure drum boiler unit. TGME - 206-COB, Russia (158 kG_f cm^-2, capacity steam generation 670 ton h^-1, 210 MW unit) of a thermal power station in Bangladesh. The deposit and loose impurities consist of Fe₂O₃, CaO, MgO and SiO₂. On area basis the maximum quantity(98g ^-2) of deposit was measured at boiler WWTs. During c leaning operation the loose impurities were withdrawn at first by flashing of the water. TSAC operation was carried out at two stages by re-circulation of hot 105 (±5°C) cleaning solution H₂SO₄+N₂H₄.H₂O (250±25 mg L^-1) at pH 2.0 (±0.5) for 24 h. The TSAC operation revealed that not less than 95% of impurities were removed . The cleaning mechanism and passivation on clean surface of tubes by circulation of 500 mg L^-1 N₂H₄ and 0.4% NH₄OH with pH 10.8 (±2) at 60° C were found to be satisfactory. Page(s): 223-226

Vehicular pollution control- removal of carbon monoxide through catalytic converters

Tue, 01 May 2001 00:00:00 GMT

Title: Vehicular pollution control- removal of carbon monoxide through catalytic converters Authors: Garg, Anurag; Chand, Shri Abstract: In an attempt to find a substitute to noble-metal based catalysts in the catalytic converters for the removal of CO from automotive exhaust, non-noble metal based catalysts of perovskite based oxides were tested. Perovskites of the structure ABO₃, where A cation had La, Ba or Ca and B cation had Co or Fe were used for the reaction. Substituted perovskite of the form A_1-xA'_xBO₃, where A' was Ce metal, was also used. The perovskite catalyst were tested in unsupported as well as supported forms. The supports used were zirconia, ceria or a mixture of the two in different proportions. The results indicate that among the unsupported catalysts, LaCoO₃ is the best. Among the substituted catalysts, La_0.3Ce_0.7CoO₃ gave the best performance showing 100% CO conversion at 200°C. The support, zirconia (20%) and ceria (80%) mixture was found to be the best combination. The durability runs up to 6 h show the activity pattern in the order: La_0.3Ce_0.7CoO₃ > La_0.6Ce_0.4CoO₃ >LaCoO₃. Page(s): 219-222

Flotation-separation of the pollutant species of chromium, cadmium and lead from aqueous solutions and natural waters

Tue, 01 May 2001 00:00:00 GMT

Title: Flotation-separation of the pollutant species of chromium, cadmium and lead from aqueous solutions and natural waters Authors: Ghazy, S E; Kabil, M A; Shallaby, A M; Ammar, N S Abstract: Simple, rapid and accurate procedures have been presented for removing the pollutant species of chromium, cadmium and lead from different aqueous media. To achieve this goal, precipitate flotation was the method of choice for this investigation using oleic acid (HOL) as a surfactant.Cr(III) as its hydroxide and Cr(VI) as Ag₂CrO₄ or Ag₂Cr₂O₇ are removed in the pH ranges 6.2-6.8 and 6.0-7.5, respectively. 2,4,6-Tri(2-pyridyl)-1,3,5-triazine (TPTA), in the presence of KI, and chloranilic acid (CAA) are found to be the most effective complexing agents for the flotation of trace amounts of Cd(II) and Pb(II) over the pH ranges 6-7.5 and 4-7, respectively. The effects of surfactant and analyte concentrations, foreign ions and temperature have been examined. The application of these procedures to recover the analytes added to natural water samples has been investigated. Since the system Cr(VI)/Cr(III) is toxic, it occurs in industrial effluents and some natural waters, a procedure for the selective separation of Cr(VI) from Cr(III) is suggested as a useful tool for speciation studies. Moreover, the flotation mechanism is proposed. Page(s): 211-218