Search Results

1 - 10 of 192 items :

Clear All
Spatial temporal variability of maximum flow in Slănic, Teleajen and Prahova River Basins

concernant le changement climatique global , În vol. Leş risques liés au temps et au climat. XIX-e Colloque Internaţionale de Climatologie, Université Denis Diderot (PRODIG) de Paris : 282-287 Hristova, Nelly (2015) Seasonal river flow variability of the Middle and Lower Danube and its tributaries Milly, Paul CD, Kathryn A. Dunne, Aldo V. Vecchia (2005) Global pattern of trends în streamflow and water availability în a changing climate Nature438.7066:347-350 Nedelcu A., (2010), Valea Prahovei și sistemul său fluviatili – Studiu de geografie fizică

Open access
Design and simulation of a multienergy gamma ray absorptiometry system for multiphase flow metering with accurate void fraction and water-liquid ratio approximation

References 1. Scheers, A. M. (2000). An oil/water/gas composition meter based on multiple energy gamma ray absorption (MEGRA) measurement . ETDEWEB ID:20061564. 2. Holstad, M. B. (2004). Gamma-ray scatter methods applied to industrial measurement systems . Unpublished Ph.D. thesis, Department of Physics and Technology, University of Bergen, Norway. 3. Scheers, A., & Letton, W. (1996). An oil/water/gas composition meter based on multiple energy gamma ray absorption (MEGRA) measurement. In Proceedings of 14th North Sea Flow Measurement Workshop

Open access
Reaction Kinetics of Carbon Dioxide in Aqueous Diethanolamine Solutions Using the Stopped-Flow Technique

aqueous ethylenediamine, ethyl ethanolamine, and diethyl monoethanolamine solutions in the temperature range of 298-313 K, using the stopped-flow technique". Ind Eng Chem Res. 2008;47:991-992. DOI 10.1021/ie0715613. SFM-20 User's Manual v. 2.1 - August 2008. MCS-200 User's Manual v. 1.1 - June 2007. Benamor A, Ali BS, Aroua MK. Kinetic of CO 2 absorption and carbamate formation in aqueous solutions of diethanolamine. Korean J Chem Eng. 2008;25:451-460. DOI 10.1007/s11814

Open access
Water flow model for the Harrier Basin, Kurdistan of Iraq

Abstract

Sharif A.J., Elias Z.R., Omar M.F.: Water flow model for the Harrier basin, Kurdistan of Iraq. Ekologia (Bratislava), Vol. 32, No. 2, p. 242-247, 2013.

The study includes computer topographic and morphologic simulation of water flow produced using a watershed modelling system that uses hydrologic and physical data from the study area. The DEM module, TIN module, Map module and Hydrologic module were used in this study. A land use data, a soil data and rainfall data were used to produce a curve that illustrates quantity of water flow versus time of water flow across the Harrier basin. The calculated water loss rate can be attributed to a number of factors such as joints, faults, bedding and land use (agriculture and forest). Land use and soil characteristics are both important factors affecting water flow rates. The climate in the Harrier basin is semi-arid. Simulated flow data indicate that the top flow rate is 32 m3/s and that water can reach to the basin outlet in 3 hours and 10 minutes.

Open access
Flow dynamics study of catalyst powder in catalytic cracking unit for troubleshooting

Abstract

Gamma scanning and radiotracer applications are very effective and inexpensive tools to understand and optimize the process as well as troubleshoot the various types of problems in many chemical, petrochemical industries and refineries. These techniques are non-invasive; hence, the problems can be pinpointed online, which leads to reduce the downtime, schedule the shutdown and maintenance of the plant equipment, rendering huge economic benefits. In a leading refinery of India, the catalytic cracking unit (CCU) was malfunctioning. It was suspected by the refinery engineers that the catalyst powder was being carried over to the fractionator, which could have led to erosion of the fractionator column internals resulting in their rupture, and consequentially, to the fire hazard. To understand the flow behaviour of the catalyst powder and to ensure the mechanical integrity, catalyst accumulation and choking, both radiotracer study and gamma scanning of the CCU reactor was carried out. The reactor consists of a riser, three primary cyclones and three secondary cyclones. Gamma scanning of the reactor was carried out with the help of an automatic gamma scanner using 1.8 GBq of Co-60 sealed source. Results showed that the catalyst powder was accumulated in one of the secondary cyclones and uneven density distribution was observed in another secondary cyclone. The radiotracer study was carried out using the irradiated catalyst powder as a radiotracer, which contains 0.9 GBq of Na-24. The radiotracer was injected in the reactor through the specially fabricated injection system. Radiation measurement was done using the thermally insulated and collimated NaI(Tl) scintillation detectors located at various strategic locations coupled to a multi-detector data acquisition system. The data were mathematically analysed. It was confirmed that the catalyst powder was accumulated in one of the secondary cyclones with no flow downwards. This resulted in excess powder available to travel along with hydrocarbon towards fractionator. Since the quantity of powder released through the hydrocarbon outlet of CCU was higher than the designed value, the catalyst powder was observed in various zones of the fractionator. Mathematical modelling of the radiotracer data obtained at various locations corroborated the scanning results; also, the flow pattern was obtained. Partially blocked secondary cyclone showed plug flow with recirculation; normal working cyclone had plug flow behaviour and the vortex breaker showed parallel flow.

Open access
Preparation of needle-like aragonite particles from calcium nitrate solution in batch and flow reactors

Preparation of needle-like aragonite particles from calcium nitrate solution in batch and flow reactors

Needle-like aragonite particles for application in paper industry were synthesised from calcium nitrate solution. Calcium nitrate was prepared from waste lime. Samples of precipitated aragonite were prepared both in batch and flow reactors, respectively. Conditions (concentration of calcium nitrate, temperature, and flow rate of CO2) were optimized for achieving high yield of aragonite in the product.

Open access
Determination of Ammonium Concentration in Post-Process Waters from Underground Coal Gasification

Abstract

A flow injection analysis method for spectrophotometric determination of ammonium in waters produced during underground coal gasification (UCG) of lignite and hard coal was described. The analysis of UCG water samples is very difficult because of their very complicated matrix and colour. Due to a huge content of organic and inorganic substances and intensive colour of samples (sometimes yellow, quite often dark brown or even black), most analytical methods are not suitable for practical application. Flow injection analysis (FIA) is based on diffusion of ammonia through a hydrophobic gas permeable membrane from an alkaline solution stream into an acid-base indicator solution stream. Diffused ammonia causes a colour change of indicator solution, and ammonia is subsequently quantified spectrophotometrically at 590 nm wavelength. The reliability of the results provided by applied method was evaluated by checking validation parameters like accuracy and precision. Accuracy was evaluated by recovery studies using multiple standard addition method. Precision as repeatability was expressed as a coefficient of variation (CV).

Open access
Utility of N-Bromosuccinimide as a Green Chemical Reagent for Determination of H2-Receptor Antagonists in their Pharmaceutical Dosage Forms

monolithic column. J. Pharm. Biomed. Anal. 2005 , 39 , 677–680. 7. Luo, J.W.; Chen, H.H.Q. Determination of cimetidine in human plasma by use of coupled-flow injection, solid-phase extraction, and capillary zone electrophoresis. Chromatographia 2001 , 53 , 295–300. 8. Badair, M.M.; Korany, M.A.; Elsayed, M.A.; Fahmy, O.T. Spectrofluorimetric determination of three pharmaceutical thiocompounds and allopurinol using mercurochrome. Spectrosc. Lett. 1990 , 23 , 161–173. 9. El-Bayomi, A.; El-Shanawany, A.; El-Sadek, A.; Abd El-Sattar, A

Open access
Axial profiles of heat transfer coefficients in a liquid film evaporator

. Portalsky S (1963) Studies of falling liquid film flow, Chem. Eng. Sci. 18: 787-804.

Open access
The dynamic simulation of the natural gas transportation

References [1]. I. Creţu and Al. Stan, Fluid Transport through Pipelines. Applications and Problems (in Romanian) Technical Publishing House, Bucuresti, 1984 [2]. C. Eparu, S. Neacsu, M. Albulescu and R. Radulescu, Considerations on the Simulation of Gas Flow Dynamics in Transport Systems (in Romanian) Termotehnica Revue, Supplement no. 1/ 2011 [3]. C. Trifan, M. Albulescu and S. Neacsu, Fluid Mechanics and Technical Thermodynamics (in Romanian) Petroleum-Gas University Publishing House, 2005, Ploiesti

Open access