CATALYTIC HYDROTREATMENT OF PETROLEUM RESIDUE

Iraqi reduced crude (350°C+) with a sulfur content of 4.3 wt% and a total metal content (Ni+V) of 141 WPPM was n-heptane deasphalted at specified conditions. The deasphalted oil (97.2 wt% of original residue) contains 4.1 wt% of sulfur and 103 ppm of metal. The original reduced crude and deasphalted oil were hydrotreated on a commercial Ni-Mo-alumina catalyst presulfided at specified conditions in a laboratory trickle-bed reactor. The reaction temperatures varied from 300 to 420°C with the liquid hourly space velocity (LHSV) ranging from 0.37 to 2.6 h^-1. Hydrogen pressure was kept constant throughout the experiments at 6.1 MPa, with a hydrogen/oil ratio of about 300 NLL^-1 (normal liters of hydrogen per liter of feedstock). Analysis for sulfur, nickel, vanadium and n-pentane asphaltenes were carried out for hydrotreated products from both the original residue and the deasphalted oil. The comparison of the results obtained for the hydrotreatment of deasphalted oil and original reduced crude indicates that the removal of sulfur, nickel and vanadium was higher for the deasphalted oil than those obtained for the non-deasphalted residue over the entire range of conversion. The exclusion of extremely high molecular weight asphaltenes by n-heptane deasphalting seems to improve the access of oil into catalyst pores resulting in higher desulfurization and conversion of the lower molecular weight asphaltenes. The sulfur content of n-pentane precipitated asphaltenes remained unchaneed with LHSV for various temperature for hydrotreated products produced from both deasphalted oil and original reduced crude.     

Release of furosemide from sustained release microcapsules prepared by phase separation technique

Furosemide Eudragit RL-100 sustained release microcapsules were prepared using phase separation technique. The results of the release studies, in sorensen phosphate buffer at PH 7.4, indicated good sustained release of the prepared microcapsules. Increasing drug to polymer ratio resulted in a decrease in the release, while increased release obtained by increasing the PH of the dissolution medium. Dosing of healthy human volunteers with sustained release microcapsules resulted in a reduced and sustained urine volume compared to the profuse diuresis obtained with the conventional furosemide capsules.     

A new video compression algorithm for different videoconferencing standards

In this paper, a new and simple predictive coding algorithm for video compression and multimedia communication for different network applications is investigated. This algorithm is called semi‐hexagonal absolute moment block truncation coding (SH‐AMBTC). It enjoys better objective and subjective qualities over the standard square shaped AMBTC. This technique based on the prediction of the bit‐map of the middle frames in a sequence from the bit‐map of the end frames (the first and the last frames in the group). It is of very low complexity comparing to the standard algorithm MPEG. The new algorithm adds no complexity to the existing AMBTC algorithm. Copyright © 2002 John Wiley & Sons, Ltd.     

Investigation of heat and mass transfer in a gauze‐type structured packing liquid desiccant dehumidifier

In this experimental investigation, a packed bed column suitable for 5‐ton hybrid cooling system has been designed to study the absorption of water vapour from moist air by contact with aqueous solutions of calcium chloride. The packing material used in the study was two elements of the BXPEP structured packing and the height of the each element was 17 cm. This packed bed dehumidifier handles desiccant flow rates from 10 to 32 l/min. This paper presents results from a detailed experimental investigation of the heat and mass transfer between a liquid desiccant (calcium chloride) and air in a gauze‐type structured packing dehumidifier. The effects of different independent variables such as air inlet absolute humidity, desiccant inlet temperature, flow rate and its concentration on the performance of the dehumidifier have been investigated. Copyright © 2002 John Wiley & Sons, Ltd.     

Volumetric Mass Transfer Coefficient in non‐Newtonian Fluids in Spout Fluid Beds

The volumetric liquid‐phase mass transfer coefficient, k_La, was determined by absorption of oxygen in air using six different carboxy‐methyl cellulose (CMC) solutions with different rheological values in three phase spout‐fluid beds operated continuously with respect to both gas and liquid. Three cylindrical columns of 7.4 cm, 11.4 cm, and 14.4 cm diameters were used. Gas velocity was varied between 0.00154–0.00563 m/s, liquid velocity between 0.0116–0.0387 m/s, surface tension between 0.00416–0.0189 N/m, static bed height between 6.0–10.8 cm, and spherical glass particles of 1.75 mm diameter were used as packing material. A single nozzle sparger of 1.0 cm diameter was used in the spouting line. The volumetric mass transfer coefficient was found to increase with gas velocity, liquid velocity, and static bed height and to decrease with the increase of the effective liquid viscosity of the CMC solution. A dimensionless correlation was developed and compared with those listed in the literature.     

Investigation of the specific interfacial area of a palm oil–water system

Oil–water dispersions have many important applications in the chemical and oleochemical industries. A measure of the specific interfacial area of the dispersed phase provides a direct indication of the quality of the dispersion. In this study, the specific interfacial area for the palm oil–water system was determined using a microscopic technique. The effects of oil volume fraction, agitation speed and temperature on the specific interfacial area have been determined experimentally and an empirical correlation to predict the total specific interfacial area under different operating conditions is proposed. This correlation can be used in the design of reaction and non‐reaction systems using palm oil–water dispersions. Copyright © 2004 Society of Chemical Industry     

Measurement of large gasndashliquid interfacial areas

The light attenuation technique has been modified to expand the range of its applicability up to AL values of 460. This has been accomplished through the use of a laser as the source of monochromatic collimated light, and a very sensitive low-bias picoammeter. The data obtained using the photographic technique were found to agree reasonably well with those from light attenuation.     

Evaluation of dams as a recharge method

Dams are used for recharge purposes in many parts of Saudi Arabia. In spite of the importance of such a method, no detailed study exists on its performance. As a part of a comprehensive research project dealing with all aspects of dams as a recharge tool in the central region of the country, data on reservoirs’ water levels, meteorological parameters and observation wells were collected at two recharge dam sites. These data were used in a water budget approach to estimate efficiency. Contrary to the established belief that this method of recharge is poor, results show that between 82% and 94.5% of water stored in the two reservoirs was taken into the soil.