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Simulation of circulating fluidized bed gasification for characteristic study of pakistani coal

Ramzan N., Athar M., Begum S., Ahmad S. W., Naveed S.

Polish Journal of Chemical Technology

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2015

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Vol. 17, nr 1

66--78

EN

A process model for turbulent pressurized circulating fluidized-bed coal gasifier is created using ASPEN PLUS software. Both hydrodynamic and reaction kinetics parameter are taken into account, whose expressions for fluidized bed are adopted from the literature. Various reactor models available in ASPEN PLUS with calculator as External Block are nested to solve hydrodynamics and kinetics. Multiple operational parameters for a pilot-plant circulating fluidized-bed coal gasifier are used to demonstrate the effects on coal gasification characteristics. This paper presents detailed information regarding the simulation model, including robust analysis of the effect of stoichiometric ratio, steam to coal ratio, gasification temperature and gasification agent temperature. It is observed that, with the increase in the flow rate of air, the components hydrogen, carbon monoxide, carbon dioxide and methane reduce, which causes the Lower Heating Value (LHV) of synthesis gas (Syn. Gas) to decrease by about 29.3%, while increment in the steam flow rate shows a minute increase in heating value of only 0.8%. Stoichiometric ratio has a direct relationship to carbon conversion efficiency and carbon dioxide production. Increasing the steam to coal ratio boosts the production of hydrogen and carbon monoxide, and causes a drop in both carbon dioxide concentration and the conversion efficiency of carbon. High gasifying agent temperature is desired because of high concentration of CO and H2 &ensp, increasing carbon conversion and LHV. A high gasifying agent temperature is the major factor that affects the coal gasification to enhance H2 &enspand CO production rapidly along with other gasification characteristics.

2

Corrosion inhibition of mild steel in HCl solution by Tinidazole

Reza I., Saleemi A.R., Naveed S.

Polish Journal of Chemical Technology

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2011

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Vol. 13, nr 1

67-71

EN

Tinidazole, a pharmaceutical compound has been investigated with reference to the inhibition of mild steel acidic corrosion in 1 molar HCl by means of weight loss and electrochemical measurements. The outcomes attained at 30°C revealed that the Tinidazole had obtained 90% inhibition efficiency at 400 ppm concentration. These results explain that the inhibition process occurs by means of adsorption. The inhibitor molecules adsorb on the surface of the metal, following Langmuir's adsorption isotherm. Potentiodynamic polarization measurements established that Tinidazole is an inhibitor of a mixed type. An appropriate equivalent electric circuit for modeling and the analysis of impedance data to give a better explanation of the process of corrosion inhibition have been proposed.

3

An RP-HPLC method for simultaneous analysis of, and interaction studies on, enalapril maleate and H 2 -receptor antagonists

Sultana N., Arayne M. S., Naveed S., Shamshad H

Acta Chromatographica

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2009

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Vol. 21, no. 4

547--558

EN

A simple, sensitive, and rapid RP-HPLC method for analysis of enalapril in the presence of H 2 -receptor antagonists has been developed and validated. Enalapril maleate was separated from H 2 -receptor antagonists by use of a 250 mm × 4.6 mm, 5-µm particle, C 18 column with 86:14 ( υ / υ ) methanol-water, pH adjusted to 3.5, as mobile phase, at a flow rate of 1.5 mL min -1. UV detection was performed at 227 nm. The retention times of enalapril maleate, ranitidine, cimetidine, and famotidine were 3, 5, 7, and 7.5 min, respectively. The detection limit for enalapril was 10 ng mL -1 and the calibration plot was linear in the range 2.5–50 µg mL -1. In-vitro interaction of enalapril with the commonly administered H 2 -receptor antagonists cimetidine, ranitidine, and famotidine in simulated gastric juice at different pH and 37°C was also studied by use of this method. These studies clearly indicated that most of these H 2 -receptor antagonists bind to enalapril causing drastic changes in the availability of the drug. The HPLC method is accurate, selective, sensitive, and reproducible.