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Downstream Processing of Heavier Petroleum Fractions
Published in Prasenjit Mondal, Ajay K. Dalai, Sustainable Utilization of Natural Resources, 2017
Shubham Saroha, Prasenjit Mondal, Deepak Tandon
Heavy crude oil is thicker with an American Petroleum Institute (API) gravity of less than 20°, more resistant to flow, and usually contains higher levels of sulfur and other contaminants than light crude oil. It gives more residues after the processing of crude oil from the vacuum distillation unit than light crude oil. According to the density, heavy crudes can be classified as heavy oils (API within 10°–20°) and extra heavy oils (API < 10°) (Manning and Thompson 1995). The in situ viscosity makes the distinction between extra heavy oils and bitumen. It is reported that during the past 15 years (2001–2015), the demand for petroleum products has grown with a rate of ~1.7% per annum, which is also expected to continue over the next 15 years (Hedrick and Seibert 2006)(Web 1). Further, the supplies of light crudes have diminished in recent years, whereas global heavy oil consumption is increasing gradually, and it is predicted to continue until 2030 (World Energy Outlook 2008). Therefore, both the heavy crude oil containing 40%–64% residues and the nondistillable heavy residues produced from it attract strong interest from the refiners to produce valuable products (Speight 2000; Marafi et al. 2010).
Crude Oil and Asphaltene Characterization
Published in Francisco M. Vargas, Mohammad Tavakkoli, Asphaltene Deposition, 2018
R. Doherty *, S. Rezaee *, S. Enayat, M. Tavakkoli, F. M. Vargas
Oil viscosity is a strong function of many thermodynamic and physical properties such as oil composition, gas-to-oil ratio (GOR), temperature, and pressure and saturation pressure. As expected, viscosity increases with decreases in crude oil API gravity and decreases with temperature. Also, the gas dissolved decreases the viscosity. Above saturation pressure, viscosity increases almost linearly with pressure. Viscosity is usually determined by experimental methods at the temperature of the reservoir; however, many correlations have been developed to predict the viscosity of crude oil at the reservoir conditions of temperature and pressure (Alomair et al. 2016; Riazi and Al-Otaibi 2001; Al-Rawahi et al. 2012).
Instability and Incompatibility
Published in James G. Speight, Refinery Feedstocks, 2020
The viscosity of a feedstock varies with the origin and type of the crude oil and also with the character of the chemical constituents, particularly the polar functions where intermolecular interactions can occur. For example, there is a gradation of viscosity between conventional crude oil, heavy oil, and bitumen (Speight, 2014a, 2015). Viscosity is a measure of fluidity properties and consistency at specific temperatures. Heavier crude oil, i.e., crude oil having lower API gravity, typically has higher viscosity. Increases of viscosity during storage indicate either an evaporation of volatile components or formation of degradation products dissolving in the crude oil.
Remediation of oil spill polluted water from Niger Delta Nigeria by sorption onto ammonium sulfate modified Dialium guineense seed husk
Published in Petroleum Science and Technology, 2019
Samson I. Eze, Kovo G. Akpomie, Chidinma C. Ezeofor, Nkiru V. Mmadubuike, Francis K. Ojo
The physical analysis of the crude oil determined showed viscosity of 4.8 cSt, density of 0.89 g/cm3 and API gravity of 35.6°. The API gravity which is an important property in the classification of crude oil as heavy, medium, light and very light showed the used crude fell within the range of light crude oil (34–390C) (Akpomie et al. 2019). The FTIR spectra of the sorbents before and after ammonium sulfate modification are presented in Figure 1. The spectra showed the existence of several functional groups which could interact with crude oil. On DGSH surface, bands at 3385.2 and 3331.2 cm−1 can be attributed to the O-H or N-H stretching vibrations, while bands at 2920.3 and 2852.8 cm−1 are due to the –C-H groups. Absorptions at 2345.5 and 2065.4 cm−1 are related to the CH3- stretching vibrations of aliphatic compounds, while bands at 1518.0 – 1735.9 cm−1 are attributed to the –C = O group. Bands observed at 1039.2–1440.8 cm-1 indicated the presence of the C = C and C-O functionalities (Chukwuemeka-Okorie et al. 2018). The spectrum for the modified sorbent AS-DGSH (Figure 1b) showed shifts in the broad band obtained at 3385.2 and 3331.2 cm−1 to more intense band at 3404.4 cm−1. This is a clear indication of the fictionalization of the N-H group on the surface of the modified sorbent. Also, significant shifts in absorption were observed at almost every region of the spectrum with more intense peaks suggesting efficient alteration of the surface of the sorbent after ammonium sulfate treatment. The BET surface area (SBET) showed values of 379.0 m2/g for DGSH with increase in SBET of 624.857 m2/g recorded for AS-DGSH. Also a total pore volume of 0.130 and 0.275 cm3/g was obtained for DGSH and AS-DGSH respectively. The increase surface area and pore volume of the modified sorbent is desirable and suggest improve sorption capacity of AS-DGSH for sorbate molecules (Akpomie and Dawodu 2016). The photographs in Figure 2 depict the SEM images of DGSH and AS-DGSH at different magnifications respectively. The surface structures of both sorbents showed some degree of porosity which slight increase in surface porosity of AS-DGSH which would be utilized for crude oil sorption. The surface structure of the modified sorbent was different from that of the unmodified, which is an indication of successful alteration of the surface of the sorbent by ammonium sulfate treatment.