Amal Elkilani

Retardation of asphaltene precipitation by addition of toluene, resins, deasphalted oil and surfactants

Abstract The aim of this work is to test the possibility of using deasphalted oil (DO) or resin (R) obtained from Kuwaiti crude to inhibit the asphaltene precipitation from such crude when n -heptane is added. The inhibition effect of toluene (T) and selected surfactants is also tested. Surfactants used are nonyl phenol (NP), dodecyl benzene sulfonic acid (DBSA), and dodecyl resorcinol (DR). The retardation of asphaltene precipitation with addition of inhibitor is found to be in the order: DR>DBSA>NP>R>T>DO. These results show that toluene and DO are not effective inhibitors. Their effect on the onset point becomes appreciable only when their mass fraction in the oil exceeds 60%. The resins have modest inhibition effect. The strong inhibition effect of the surfactants is due to the interaction between the acidic head of these molecules and the asphaltene. The mechanism of inhibition is explained in terms of the micellization model of Victorov and Firoozabadi. Onset point for asphaltene precipitation with n -heptane addition is calculated in the presence of different amounts of inhibitor. Calculated results agree well with experiment. It is possible by using the micellization model to predict the amount of inhibitor required for reaching a certain onset point.

Sorption of volatile organic compounds on typical carpet fibers

Measurements of adsorption isotherms for three volatile organic compounds (VOCs) (toluene, 1,2-dichlorobenzene and 1,1,1-trichloroethane) on polyacrylonitrile carpet fibers over the temperature range 25-45 degrees C were carried out in a thermogravimetric analyzer (TGA). Linear isotherms were observed in all cases with values of the Henry coefficient ranging from 0.063 to 0.941 mm. The results of additional experiments carried out in a simple test chamber containing a single source of VOC showed that the carpet fibers acted as a significant sink causing a prolonged elevation of VOC concentration in the air within the chamber. An unsteady-state model is presented, which adequately described the adsorption and desorption phenomena occurring in the test chamber and yielded realistic values of the adsorption and desorption rate constants. There was good agreement between the equilibrium and kinetic constants obtained in the TGA and test chamber experiments.

Estimation of optimum requirements for indoor air quality and energy consumption in some residences in Kuwait

Contrasting effects of the dilution of indoor generated pollutants and the energy efficiency of heating and ventilating air conditioning systems (HVAC) for indoor air quality (IAQ) and thermal comfort were studied for 10 Kuwaiti residences. The levels of volatile organic compounds (VOCs) and the calculated cooling load of the HVAC systems were used as indicators for the IAQ and for the energy consumption, respectively. Air exchange rates and VOCs levels (both indoor and outdoor) were measured. It was found that the outdoor VOC concentrations were always less than the indoor values. Therefore reduction of indoor VOC levels can be accomplished either by increasing the ratio of the makeup air to the recirculation air of the HVAC system or by increasing the infiltration airflow rate through openings. A single compartment IAQ model, modified by the authors, was used to test for the variation in the above two dilution modes and to test the performance sensitivity. Hence, the optimum parameters in terms of IAQ and energy consumption were determined. The results indicated that it was necessary to increase the ratio of the makeup air to the recirculation air from its typical design value of 0.5 to a range of 0.7-1.3 in order to reduce indoor VOC to acceptable levels.

Emissions inventory, ISCST, and neural network modelling of air pollution in Kuwait

This paper focuses on modelling of emission inventory, pollutant dispersion by the industrial source complex short term model (ISCST), and neural network analysis of air pollution in Kuwait. A novel neural network‐based scheme is suggested and applied to site‐specific short‐ and medium‐term forecasting of ozone concentrations. Two feed forward artificial neural networks (ANN) are used to improve the performance of time series predictions. Results show that this forecasting technique represents a significant improvement over the conventional ANN approach.

Analysis of indoor concentrations of benzene using an air-quality model.

Abstract We performed measurements to determine indoor benzene levels in 26 residential houses in Kuwait, located in zones of different activity levels. Pumped (or active) sampling was conducted via use of 12 sampling tubes over a period of 24 hr for both indoor and outdoor concentrations simultaneously. Time-average indoor concentration varied linearly with time-average outdoor concentration in accordance with a mass-balance-based indoor air-quality model in which source and sink terms were incorporated. We used regression analysis to determine benzene adsorption rates, which appear in the removal and source terms of the model. The removal rate parameter varied between 0.12/hr and 2.16/hr, whereas source term parameter varied between 0.60 mg/hr and 76.07 mg/hr. Houses were then divided into three groups according to their benzene source strengths (i.e., < 1.0 mg/hr, 1–10 mg/hr, and 10–50 mg/hr). Qualitatively, these levels depended on the characteristics of occupants (e.g., smoking and gas cooker use, number of cars, and parking area) and location of the building.

Refinery Feedstocks and Products

This chapter describes petroleum refinerys feedstocks and different products produced by several refinery processes. A petroleum refining study starts with describing its feedstock, the crude oil and the range of products that are produced by the various processes. Crude oil comes from different parts of the world and has different physical and chemical characteristics. On the other hand, the products that are produced have to meet market requirements and as such, should comply with certain specifications. Crude oil is a complex liquid mixture made up of a vast number of hydrocarbon compounds that consist mainly of carbon and hydrogen in differing proportions. In addition, small amounts of organic compounds containing sulfur, oxygen, nitrogen, and metals such as vanadium, nickel, iron, and copper are also present. Hydrogen to carbon ratios affects the physical properties of crude oil. As the hydrogen to carbon ratio decreases, the gravity and boiling point of the hydrocarbon compounds increases. Moreover, the higher the hydrogen to carbon ratio of the feedstock, the higher its value is to a refinery because less hydrogen is required. There are specifications for over 2000 individual refinery products. Intermediate feedstocks can be routed to various units to produce different blend products depending on market demand. This chapter also explores typical refinery products with their carbon atom contents and boiling ranges, and discusses the specifications of each product.

Environmental Aspects in Refining

The safe processing of crude oil into flammable gases and liquids at high temperatures and pressures using vessels, equipment and piping requires considerable control technologies to avoid damage to the environment. Certain procedures should be established to assure compliance with applicable regulations and standards such as hazard communications, emission rates regulations, waste management and waste minimization. The refinery industry has demanding environmental management challenges to protect water, soil and the atmosphere from refinery pollution. This chapter describes the environmental aspects of refining, including air, water and soil pollution from different units in refinery processes. In each refinery unit, the effluent gas, solid and liquid wastes are pointed out. It also discusses waste treatment and waste minimization. Pollution associated with petroleum refining includes volatile organic compounds (VOCs), carbon monoxide (CO), sulfur oxides (SOx), nitrogen oxides (NOx), particulates, ammonia (NH3), hydrogen sulphide (H 2 S), metals, spent acids and numerous toxic organic compounds. These pollutants may be discharged as air emissions, wastewater or solid waste. All of these wastes are treated. However, air emissions are more difficult to capture than wastewater or solid waste. Thus, air emissions are the largest source of untreated wastes released to the environment.

Chapter 12 – Clean Fuels

Publisher Summary Environment Protection Agencies worldwide set regulations to forbid or control the pollution of the environment. Petroleum fuels are considered one of the main pollution problems. This chapter explores clear fuels, which are fuels that contain very few of components that may harm the environment, like sulfur, nitrogen, and organometallic compounds. Benzene can also be included along with polycyclic aromatic hydrocarbons. Clean fuels are free of impurities (sulfur and benzene), but sometimes work is needed to improve their properties if possible. The main ways of producing clean fuels are: deep desulfurization of fossil fuels (produced from crude oil); natural gas (NG) and gasification of coal; biofuel from available biological sources like wood, vegetable oil and seeds; and alkylation. NG is a major source of clean fuels. It can be used directly as a gaseous clean fuel or processed to produce liquid clean fuel with low aromatic and zero sulfur content. The technology that is used to convert natural gas into liquid hydrocarbon fuels is called gas-to-liquid technology. The conversion of natural gas to hydrocarbons is currently one of the most promising topics in the energy industry. Besides, coal or heavy residues can be used on sites where these are available at low costs. Coal and natural gas can be converted into synthesis gas, a mixture of predominantly CO and H2, by either partial oxidation or steam reforming processes.

Acid Gas Processing and Mercaptans Removal

This chapter discusses acid gas processing. Acid gases in a refinery are carbon dioxide (CO 2 ) and hydrogen sulphide (H 2 S). Sour gas is the gas containing sulfur compounds, such as mercaptans and carbonyl sulphide (COS). Gas with only CO 2 is called sweet gas. Although the main gas treatment processes emit CO 2 and H 2 O, CO 2 is now considered an undesired product due to its role in global warming. CO 2 is a corrosive material, non-combustible and captures solar radiation if released into the atmosphere therefore, warming the earths atmosphere. H 2 S is a highly toxic, flammable gas with an auto-ignition temperature of 292 o C (500 o F). H 2 S is 1.18 times heavier than air. Therefore, it may accumulate in dangerous concentrations in drains, valve pits, vessels and tanks. A hydrogen sulphide concentration must be less than 6 mg/m3 (43 ppm) to prevent the effect of corrosion in process equipment. Most industrial personnel gas detectors are set to 20 ppm of H 2 S in air as a limit for the escapemode from an area. This chapter also discusses and mercaptans removal in refineries. The predominant sulfur compounds in refinery products that usually have an unpleasant smell are mercaptans. They are corrosive and disturb the fuel stability due to gum formation. The principle of mercaptans removal is oxidation. The mercaptan oxidation is called MEROX process.

Chapter 9 – Product Blending

Publisher Summary Product blending is an important process in petroleum refining as refining processes do not generally produce commercially usable products directly, but rather semi-finished products which must be blended to meet the specifications of the demanded products. This chapter discusses product blending, the main purpose of which is to find the best way of mixing different intermediate products available from the refinery and some additives to adjust the product specifications. The final quality of the finished products is always checked by laboratory tests before market distribution. Gasolines are tested for octane number, Reid vapor pressure (RVP) and volatility. Kerosenes are tested for flash point and volatility. Gas oils are tested for diesel index, flash point, pour point and viscosity. Product qualities are predicted through correlations that depend on the quantities and the properties of the blended components. In the discussion, various mixing rules along with correlations are used to estimate the blend properties such as specific gravity, RVP, viscosity, flash point, pour point, cloud point and aniline point. The octane number for gasoline is correlated with corrections based on aromatic and olefin content.