Solvent extraction is a process whereby the feed stock is fractionates the vacuum distillation residue (VDR) according to the solubility/insolubility of the molecular components in a given solvent. The heaviest molecular components of the VDR, asphaltenes, can be separated by precipitation by dissolving into a light paraffin after with VDR is solubilized in an aromatic solvent such as benzene or toluene. The paraffin solvent that is used determines the type of asphaltenes that are seperated. The VDR that is dissolved in the paraffin solvent are known as maltenes with respect to the solvent used. The VDR can theoretically undergo several dissolutions using different paraffin solvents for each process. Each process produces different insoluble products such as asphaltenes, hard resin, soft resin and deasphalted oil (DAO) fractions depending on the paraffin solvent used. However, only one stage of separation is usually implemented in industry processes whereby the lightest solvent, usually propane, to produce asphalt and DAO fractions.

There are several parameters that determine the power of such non-polar solvents. The gradient solubility model provides some justification regarding how the asphaltenes in VDR can be removed through solvent extraction. The Hildebrand Solubility Parameters (HSP) determines the power of a non-polar solvent. There are two HSP definitions; the first HSP depends on the surface tension and molar volume values of the solvent. Solubility increases as surface tension increases and molar volume decreases (increasing density). The second HSP depends on the energy of vaporization and molar volume. Solubility according to this parameter increases as the heat of vaporization increases. Thus, the HSP conveniently explains why paraffins with more carbons are more powerful solvents. It also explains why aromatic solvents, such as toluene, are more powerful solvents than aliphatic hydrocarbons, such as propane. Therefore, the Hildebrand Solubility Parameters prove to be very useful when deciding which solvent to use to yield a specific product for a solvent extraction process.

Sources:

Course Webpage

Wikipedia: Solvent Extraction, Hildebrand Solubility Parameters

In petroleum refining, there are three different distillation methods used to generate laboratory data. The three distillation methods are: True Boiling Point Distillation (TBP), ASTM Distillation (ASTM), and Equilibrium Flash Vaporization (EFV). They all have their different purposes and all are vital in a different way. The degree of separation for the various methods are vastly different, with the greatest degree of separation occurring in True Boiling Point Distillation and the lowest degree of separation occurring in Equilibrium Flash Vaporization. Each of these methods have different applications in a given refinery.

The first of the three methods, True Boiling Point Distillation, uses a batch distillation operation that incorporates more than 100 theoretical plates and a high reflux ratio of 100. It is an ideal method used to generate the best separation possible, and is used to characterize crude oils and constitute a significant component of crude assay.

The second, ASTM Distillation, also uses batch operation, the difference from True Boiling Point Distillation is that it operates without the presence of contact plates, and has a reflux ratio of zero. This method is used for refinery products and property calculations and correlations for distillate fractions

The third and final method, Equilibrium Flash Vaporization, involves heating a flowing feed and the separation of the liquid and vapor in a flash drum, and generates the lowest degree of separation of any of the methods. This method provides useful data for flashing operations in the refinery.

References:

https://cms.psu.edu/section/content/default.asp?WCI=pgDisplay&WCU=CRSCNT&ENTRY_ID=F20C6357261A4AE2A750C141B721E8C1

Vacuum distillation is the distillation of crude oil at a pressure lower than atmospheric pressure because reducing the pressure lowers the boiling point of the crude oil. Furthermore, the vacuum is also used to separate the heavier portion of the crude oil into fractions because the extremely high temperatures that are necessary to vaporize the topped crude at atmospheric pressure would cause thermal cracking to occur. Other disadvantages that would be avoided include the loss due to dry gas, discoloration of the product, and equipment damage as a result of coke formation. Also, addition of steam to the process increases the furnace tube velocity and reduces coke formation in the furnace as well. It also decreases the total hydrocarbon partial pressure in the vacuum tower.

Selecting the vacuum distillation temperature is crucial for the process to control the coking in the system. The Watson Characterization Factor (Kw) is a value derived from the physical properties of the crude oil used to classify it. The Kw for the crude oil may be used to approximate the upper temperature limit for vacuum distillation that would cause coking. The empirical correlation between Kw and the temperatures above is known as the decomposition zone. Thus, a band of temperatures maybe determined whereby there maybe a possibility of coking occurring. For a temperature below such a band, there is negligible coking. In addition, vacuum distillation temperatures should be selected with particular consideration regarding the composition of the crude oil. Crude oils with high Kw are highly paraffinic and are heated using lower temperatures to avoid thermal cracking. However, higher temperatures maybe used for crude oil with lower Kw factors, such as naphthenes and aromatics, because they are more stable.

References:

Gary, James H., Glenn E. Handwerk, and Mark J. Kaiser. “4 Crude Distillation.” Petroleum Refining: Technology and Economics. Boca Raton: CRC, 2007. Print.

Websites:

http://en.wikipedia.org/wiki/Vacuum_distillation

http://en.citizendium.org/wiki/Vacuum_distillation

https://www.e-education.psu.edu/fsc432/content/selecting-right-temperature

Crude oil is a raw mixture of many different hydrocarbon compounds such as aliphatic, aromatic and naphthenic compounds. The three different distillation methods used to separate crude oil according to the compounds’ boiling point. They are: True Boiling (TBP), ASTM, and Equilibrium Flash Vaporization (EFV) Distillation. Each method has a specific use in the petroleum industry.

TBP distillation according to the ASTM D-2892 standard is one of the most reliable processes for characterization of crude oil and raw petroleum mixtures according to their boiling point distribution. It is an idealized batch operation whereby components of the crude oil are separated in a distillation process utilizing a large number of theoretical plates for liquid vapor contact in the column and an extremely high reflux ratio. Perfect separation of the components of the crude oil would be achieved if TBP were used. The components. The process of TBP distillation is used to characterize crude oils and constitute a significant component of crude essay. Yet, TBP distillation is considered a very expensive and time-consuming procedure.

ASTM distillation also uses a batch method, but it works without the presence of a contact plate and has a reflux ratio of zero. Some unintentional reflux may occur because of the condensation of the vapor on the tube that connects the flask to the condenser. It is a rapid procedure generally used to for petroleum products, process calculations and correlations for distillate fractions.

Equilibrium Flash Vaporization Distillation involves heating a flowing supply of crude oil and the separation of the liquid and vapor in a flash drum. The supply is heated as it flows through a heating coil. Vapor formed continues along in a tube with the remaining liquid until separation is possible in a vaporizer. EFV provides useful data for flashing operations in the refinery.

References:

Gary, James H., Glenn E. Handwerk, and Mark J. Kaiser. “4 Crude Distillation.” Petroleum Refining: Technology and Economics. Boca Raton: CRC, 2007. Print.

Websites:

https://www.e-education.psu.edu/fsc432/content/distillation-methods

http://connection.ebscohost.com/c/articles/86047211/boiling-point-distribution-crude-oils-based-tbp-astm-d-86-distillation-data

http://www.astm.org/Standards/D86.htm

http://petroleum-industry-eng.blogspot.ae/p/true-boiling-point-curve.html

http://petroleum-industry-eng.blogspot.ae/p/equilibrium-flash-vaporization.html

While exploring the United States Energy Information Administration’s website I came across plenty of statistics pertaining to this country’s supply of petroleum fuels. While the administration does consistently update their information on a weekly basis, I found that most of their analysis stems from their numbers in 2012. A majority of the pages within the website also discussed the United States dependence petroleum imports. For example, I just learned that Canada is the leading supplier of these products to the U.S.  Since 2005, the peak year of foreign petroleum dependence, this country’s dependence on other nations support has followed a downward trend. As of 2012 the United States has dropped its dependence on foreign imports to 40% (11.0 million barrels per day). This is due to a whole host of reasons, some of which are a decrease in U.S. consumption, the economic downturn in 2008, and improvements in efficiency. Despite all of this, the U.S. is the world leader in petroleum consumption totaling off at 18.6 million barrels per day, as of 2012.

With so many statistics on petroleum supply and usage, the Energy Information Administration was able to put together a projection for the U.S. energy consumption for the year 2040. Taking population increase, technological developments, and current trends into account they believe that consumption will stay about what it is today. The administration was able to separate the three main uses for petroleum and analyze the situation that way. Transportation, which uses the most petroleum by far, is likely to drop its share of the total consumption from 72% in 2013 to 65% in 2040. They also believe that petroleum used for chemical purposes will increase by 1.3 million barrels per day by 2040. The opposite trends in the chemical business and transportation industry is the reason why the government believes that our petroleum consumption will turn out to be very similar to what it is today.

What I found the most interesting about administration’s projections was that they left no room for more progressive future inventions or new ways to power our transportation vehicles. With the EPA’s more advanced operations and our increasing knowledge of harmful effects on the environment it is hard to believe that we will not have a clean solution to this mess that we’ve created. In the meantime, the Environmental Protection agency is on the attack with its Clean Air Act and all of its requirements. Burning a gallon of gasoline results in 19.6 pounds of carbon dioxide, which is an extremely harmful greenhouse gas. Since 1970 (the establishment of the Clean Air Act) the EPA has been adding amendments to the act in order to coexist with the current times. They have required emission control devices in vehicles, removed lead from gasoline (once scientifically proved as harmful to humans and the environment), lowered the sulfur in gas, and reduced the risk of leaks. All of this shows that they are making an effort to create a cleaner environment, but I still feel like there is more to be done. I am interested to see where the future will take us.