THE IMPACT OF ASPHALTENES REMOVAL ON THE KINETICS OF RESIDUUM HYDROTREATING

Iraqi reduced crude (above 350°C) prepared in a laboratory distillation unit containing 15 trays was solvent deasphaltened at specified conditions using n-heptane as the precipitant Both the original and deasphaltened reduced crude was hydrotreated on a commercial Ni-Mo- alumina catalyst in a laboratory trickle bed reactor. This investigation was undertaken to understand the role of asphaltenes removal in the kinetics of the desulphurization, demetallization and deasphaltening processes. Kinetic analysis showed that the hydrotreating reactions of the deasphaltened reduced crude followed a first order kinetics. Rate constants calculated for the above reactions are higher than those obtained in the HDS process for the original full residuum.     

A preliminary comparison of polybrominated diphenyl ether concentrations relative to lipid content and to levels of dioxins and dioxin-like polychlorinated biphenyls in Norwegian farmed Atlantic salmon (Salmo salar)

Polybrominated diphenyl ethers (PBDEs) are environmental contaminants structurally similar to polychlorinated biphenyls (PCBs), and correlations between PBDE concentrations and concentrations of lipid, PCBs, dioxins and furans in feed and farmed Atlantic salmon filet indicate PBDEs may be derived from similar sources. PBDE concentrations (3.9 ± 0.6 ng g^?1 wet wt) in farmed Atlantic salmon correlated well with lipid content and these other halogenated contaminants, however, lower concentrations of PBDEs (1.6 ± 0.3 ng g^?1 wet wt) showed no correlation. Possible explanations for the non‐linear behaviour of PBDE concentrations in Atlantic salmon are discussed.     

Effects of housing, management, and health of dairy heifers on first-lactation udder health in southwest Sweden

Data on health, management, and housing from birth to first calving were collected for 2,126 heifers on semi-monthly visits made by project veterinarians to 107 dairy herds from southwest Sweden. Additional data were obtained from the official milk- and health-recording program. Factors associated with incidence of veterinarian-treated clinical mastitis (VTCM) in the period 7 d before (d −7) to 30 d after first calving and of elevated cow composite somatic cell count (SCC, ≥200,000 cells/mL) at first test milking after first calving, respectively, were investigated using a 2-level (animal and herd) logistic regression analysis after initial screening by univariate analyses. The incidence risk of VTCM during the complete first lactation (305 d) was 10.8%. Ten percent of the diseased animals had more than 1 case of VTCM and 51% of total cases occurred from −7 to 30 d postcalving. The incidence rate of VTCM during the complete first 305-d lactation was 1.13 cases per 100 cow-mo. In total, 18.1% of the animals had elevated SCC at first test milking (mean 21 d) after calving. Veterinarian-treated clinical mastitis at −7 to 30 d postcalving was associated with higher overall incidence of mastitis in the herd and with reproductive disorders (i.e., retained placenta, endometritis, pyometra, dystocia, or twin birth). The risk of elevated SCC increased with increasing percentage of cows in the herd that, some time during the year, had had an increased udder disease score (chronically increased SCC). Other factors associated with increased risk of elevated SCC were increasing amounts of concentrates fed to 11- to 16-mo-old heifers, moving to confined housing the day of calving instead of earlier, and use of restraint measures at milking. In addition, growth rate from birth to weaning, and several feed-related variables (e.g., amount of concentrates and type of roughage given) were associated with VTCM at −7 to 30 d post-calving or elevated SCC at first test milking in the univariate analyses.     

THE EFFECT OF ANTIOXIDANT ADDITIVE ON THE THERMOXIDATION STABILITY OF DISTILLATES FROM MEDIUM CRUDE OIL

ABSTRACT

Fractions 100-150, 150-200, 200-250°C were distilled from medium Iraqi crude oil. The thermo-oxidation stability experiments were carried out on original and inhibited (with Topanol 0) distillate fractions using the Alcor Jet Fuel Thermal Tester, over a temperature range 516-573 k. It was found that the antioxidant (Topanol 0) efficiency depends on the fractions composition and the oxidation temperature. Only 30 PPM of Topanol 0 stabilizes fraction 100-150°C to a considerable extent. Also, an inhibition effect is obtained in fraction 150-200°C but at a higher antioxidant concentration (90 PPM). Only, slight inhibition effect was observed in fraction 200-250°C at low oxidation temperature (below 551 K), while effect will be of no value at higher oxidation temperatures.     

THE IMPACT OF ASPHALTENES REMOVAL ON THE KINETICS OF RESIDUUM HYDROTREATING

ABSTRACT

Iraqi reduced crude (above 350°C) prepared in a laboratory distillation unit containing 15 trays was solvent deasphaltened at specified conditions using n-heptane as the precipitant Both the original and deasphaltened reduced crude was hydrotreated on a commercial Ni-Mo- alumina catalyst in a laboratory trickle bed reactor. This investigation was undertaken to understand the role of asphaltenes removal in the kinetics of the desulphurization, demetallization and deasphaltening processes. Kinetic analysis showed that the hydrotreating reactions of the deasphaltened reduced crude followed a first order kinetics. Rate constants calculated for the above reactions are higher than those obtained in the HDS process for the original full residuum.     

DELAYED COKING OF HYDROTREATED REDUCED CRUDE

ABSTRACT

A laboratory coking unit was designed and constructed for an experimental study of the delayed coking process of hydrotreated Kirkuk reduced crude. The yield and analysis of coke, gases and liquid products were obtained for each experiment. The gas < C₄. and gasoline yield decrease by increasing Liquid hourly space velocity (LHSV) while the yields of kerosene and gas oil increase and no effect of LHSV on petroleum coke yield was observed, The specific gravity of gasoline, kerosene and gas oil decreases by increasing LHSV. The increase in LHSV (decrease in residence time) decreases the olefinic hydrocarbons of produced gas oil and fraction 350-450^°C. Sulfur content of produced coke and coking residue increases by increasing residence time while it changes slightly for kerosene and gas oil. By increasing the recycle ratio (RR), the yield of gas decreases while the coke yield increases. Sulfur content of gas oil and coking residue increases with an increase in the recycle ratio while it decreases for coke. Metals content of coke decreases with an increase in the recycle ratio and coke with accepted properties for aluminum anode manufacture could be produced when a recycle ratio of 1.4 was used.     

Arsenolipids in marine oils and fats: A review of occurrence,chemistry and future research needs

Numerous studies have focused on arsenic in marine organisms, and relatively high natural levels of the element have been reported in marine samples. Despite their seemingly consistent presence in marine oils and fats, there is currently only limited knowledge available on arsenic compounds that exhibit lipid soluble characteristics, the arsenolipids, in contrast to the water-soluble arsenic species. The development of analytical techniques has, however, renewed the interest in these arsenic species and significant novel findings have been published in the last couple of years. The aim of this review is to present current knowledge on the occurrence and chemistry of arsenolipids in marine oils, and to identify future research needs. The occurrence of arsenolipids and their relevance in marine organisms will be discussed, in addition to their relevance for consumers and industry, with respect to feed and food safety and legislative issues. Analytical techniques, including techniques in the early work on arsenolipids in addition to methods employed today, and relevant sample preparation will be discussed.     

Impact of milking frequencies on the level of free fatty acids in milk, fat globule size, and fatty acid composition

The aim of the present study was to study the effect of milking cows 4 times daily on free fatty acids (FFA) in the milk compared with milking twice daily. An experiment was performed during 2 wk in which half udders in 11 cows were milked 2 or 4 times daily. Milk yield was measured, and milk was analyzed for fat content, FFA, fatty acid composition, fat globule size, and activity of γ-glutamyl transpeptidase. Concentration of FFA was greater (1.49 mEq/100 g of fat) in milk from half udders milked 4 times daily than in milk from the half udders milked twice daily (1.14 mEq/100 g of fat). Further, it was noted that milk from the half udder milked 4 times daily contained milk fat globules with larger average diameters. Increased milking frequency increased milk yield by 9% compared with the udder half milked twice daily, but fat content and fat yield were not affected. The results are of importance for further understanding the mechanisms behind the increased content of FFA that is frequently observed in automatic milking systems.     

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.     

Influence of agronomic and climatic factors on Fusarium infestation and mycotoxin contamination of cereals in Norway

A total of 602 samples of organically and conventionally grown barley, oats and wheat was collected at grain harvest during 2002-2004 in Norway. Organic and conventional samples were comparable pairs regarding cereal species, growing site and harvest time, and were analysed for Fusarium mould and mycotoxins. Agronomic and climatic factors explained 10-30% of the variation in Fusarium species and mycotoxins. Significantly lower Fusarium infestation and concentrations of important mycotoxins were found in the organic cereals. The mycotoxins deoxynivalenol (DON) and HT-2 toxin (HT-2) constitute the main risk for human and animal health in Norwegian cereals. The impacts of various agronomic and climatic factors on DON and HT-2 as well as on their main producers F. graminearum and F. langsethiae and on total Fusarium were tested by multivariate statistics. Crop rotation with non-cereals was found to reduce all investigated characteristics significantly--mycotoxin concentrations as well as various Fusarium infestations. No use of mineral fertilisers and herbicides was also found to decrease F. graminearum, whereas lodged fields increased the occurrence of this species. No use of herbicides was also found to decrease F. langsethiae, but for this species the occurrence was lower in lodged fields. Total Fusarium infestation was decreased with no use of fungicides or mineral fertilisers, and with crop rotation, as well as by using herbicides and increased by lodged fields. Clay and to some extent silty soils seemed to reduce F. graminearum in comparison with sandy soils. Concerning climate factors, low temperature before grain harvest was found to increase DON; and high air humidity before harvest to increase HT-2. F. graminearum was negatively correlated with precipitation in July but correlated with air humidity before harvest. F. langsethiae was correlated with temperature in July. Total Fusarium increased with increasing precipitation in July. Organic cereal farmers have fewer cereal intense rotations than conventional farmers. Further, organic farmers do not apply mineral fertiliser or pesticides (fungicides, herbicides or insecticides), and have less problem with lodged fields. The study showed that these agronomic factors were related to the infestation of Fusarium species and the concentration of mycotoxins. Hence, it is reasonable to conclude that farming system (organic versus conventional) impacts Fusarium infestation, and that organic management tends to reduce Fusarium and mycotoxins. However, Fusarium infestation and mycotoxin concentrations may be influenced by a range of factors not studied here, such as local topography and more local climate, as well as cereal species and variety.