Video: FSC 432 Lesson 3 (2:16)
Selected properties of crude oil provide information on its quality and the conditions for the optimum operation of a petroleum refinery for processing the crude oil to produce the desired fuels. Readily measurable physical properties of crude oil (such as density, boiling point, and viscosity) not only help in predicting the physical behavior of crude oil during refinery but also give insight into the chemical composition of the oil. Therefore, physical properties can be used in developing characterization factors that relate to the chemical behavior of crude oil and the characteristics of the resulting refinery products. In addition to using characterization factors, crude oils are classified using ternary diagrams reflecting the hydrocarbon composition in terms of paraffins, naphthenes, and aromatics.
As introduced in Lesson 1, petroleum refining integrates four types of processes: separation, conversion, finishing, and supporting processes. This lesson involves a quick walk through a simple refinery in the U.S. to see what happens to a barrel of crude oil, and to provide more detail on how different processes are sequenced for optimum operation. The simple animation below shows a simplified diagram of processing network to maximize gasoline yield and produce the other distillate fuels (jet fuel, diesel fuel, and fuel oil) in high yield.
The first sequence of processes in a refinery makes use of physical separation to wash the salt out and to fractionate the desalted crude into different boiling ranges in a distillation column. Following the distillation, these fractions are subjected to further separation processes, such as those in Light Ends Unit (LEU) dewaxing and deasphalting units; to finishing processes, such as hydrotreatment; and to conversion processes, such as catalytic cracking, hydrocracking, visbreaking, and delayed coking. As shown in the animation below, the final products from these processes include Liquefied Petroleum Gas (LPG), lubricating oil base stock, asphalt, jet fuel and diesel fuel, gasoline, fuel oil, and petroleum coke. Some fractions from LEU are sent to finishing processes (blending and hydrotreatment) and further to a conversion process (reforming) to produce additional gasoline. Light products from catalytic cracking are subjected to further conversion in the alkylation process to produce more gasoline. Finally, supporting processes, hydrogen production and sulfur recovery, help remove the major heteroatom contaminant, sulfur, from the petroleum fuels through hydrotreatment .
This refinery scheme is typical in U.S. refineries where the premium product is gasoline, as one could tell from the number of processes that lead to gasoline as the major product. The gasoline streams from different processes are blended in sophisticated linear and non-linear programming schemes to produce the three grades of gasoline sold in the U.S., regular, intermediate, and premium grades defined in reference to octane number. Elsewhere in the world, there is more emphasis on producing diesel fuel rather than gasoline, since the transportation systems are not as heavily dependent on gasoline-powered passenger vehicles. Diesel fuel is preferred for mass transport options (e.g., buses and trains), as diesel engines (with compression-ignition) can deliver more power than spark-ignition gasoline engines.
In the following sections, each major process group in a refinery network will be introduced in sequence. We will discuss how they fit in the “industrial ecology” of petroleum refining for the overall economic goal of maximizing profit in the prevailing markets for crude oil and the refined petroleum products. The video below presents a flow diagram integrating the four types of processes in a petroleum refinery.
Video: FSC 432 Simple Refinery Flow (4:36)
By the end of this lesson, you should be able to:
- illustrate the refinery processes with examples for each category of processes;
- distinguish and evaluate the functions of different refinery processes to control refinery product yield and composition;
- evaluate the principles behind the major refinery processes and examine the products from each process from Distillation to Hydrocracking;
- formulate strategies for upgrading heavy oil.
What is due for Lesson 3?
This lesson will take us one week to complete. Please refer to the Course Syllabus for specific time frames and due dates. Specific directions for the assignments below can be found on the Assignments page within this lesson.
|Readings:||J. H. Gary, G. E. Handwerk, & Mark J. Kaiser, Chapter 1, pp. 32-36; Chapter 2, pp. 41-55 and the course material from this site|
|Assignments:||Exercise 2: Using ternary classification to characterize crude oil blends|
If you have any questions, please post them to our Help Discussion (not email), located in Canvas. I will check that discussion forum daily to respond. While you are there, feel free to post your own responses if you, too, are able to help out a classmate.