Pre Assessment Oil Refining Technology
Name : --- Location: ---Co. No. : --- Date: 10/03/2008
Question No.1 MULTIPLE CHOICES: Place the letter of the
statement that best completes the sentence in space provided.
1. What happens when a mixture of hydrocarbons is distilled?
---A. The hydrocarbons are physically separated. B. They are chemically changed.
C. They all start boiling at the same temperature
2. During the distillation process, heat put into the tower:
---A. Is consumed by the hydrocarbons. B. Is always less than heat taken out.
C. Is taken out as latent heat of condensation and as sensible heat in the products themselves.
3. The temperature in a distillation column decreases from:
---A. Bottom to top. B. Top to bottom.
4. If we increase the reflux rate in a crude distillation unit and hold other operating conditions constant, which of the following will occur?
---A. Lighter overhead, bottom, and side draw products. B. Heavier overhead and side draw products.
C. Heavier bottom product. D. More overhead product.
5. What happens to the boiling point of a liquid when pressure against that liquid is increased? ---
A. The boiling point temperature is increased. B. The boiling point temperature is decreased.
C. The boiling point does not change unless the vapor pressure of that liquid changes.
6. The temperature on each tray in the tower is controlled by:
---A. The downward flow of reflux and upward flow of vapors. B. The downward flow of vapors and upward flow of reflux. C. The composition of the feed.
D. None of the above.
7. What happens on each tray as result of vapor – liquid contact?
---A. Light materials in the liquid tend to condense, and heavy materials in the vapor tend to vaporize.
B. Light materials in the liquid tend to vaporize, and heavy materials in the vapor tend to condense.
8. Good fractionation requires:
---A. A tower with a large number of trays. B. A multiple feed-port tower.
C. Multi-pass down comers.
D. Good vapor-liquid contact on each tray.
9. “Entrainment” occurs when:
---A. Vapor rates are too low.
B. Not enough heat is put into the tower.
C. Small drops of liquid suspended in vapor are carried up from one tray to the next.
10.If we increase the feed temperature in a crude distillation unit and hold other tower variables constant, which of the following will occur?
---A. Heavier overhead, bottom, and side draw products. B. Less bottom product.
C. More overhead product. D. All of the above.
11.When we heat a mixture of Hydrocarbons, the first molecule to boil and vaporize are:
---A. The heavy, or large, Hydrocarbons.
B. The light, or small, Hydrocarbons.
C. The medium-sized Hydrocarbons.
D. None of the above. They all start boiling at the same
temperature.
12. Inside the distillation column:
---A. Vapours by-pass the liquid through down comers. B. Vapours bubble through the liquid on the tray.
D. Liquid flows down the tower through bubble caps.
13. The vaporization – condensation cycle eventually produces:
---A. A different fraction on each tray. B. The same fraction on each tray.
C. A heavy product at the top of the column and a light product at the bottom.
14. As vapours rise up the column, they become progressively :
---A. Heavier. B. Lighter.
15. Liquid moving down the column becomes:
---A. Heavier. B. Lighter.
16. The heaviest fraction will be formed on the tray with the:
---A. Lowest temperature. B. Highest temperature.
17. Distillation of Hydrocarbons is easiest when the components have
boiling points that are :
---A. Close together. B. Far apart.
C. Neither of these. Boiling points do not affect distillation.
18. Fractionation is the process of: ---
A. removing toxic gas from a gas stream at the wellhead B. combining several gas streams into one
C. separating a gas stream into its component parts
19. The term ---refers to the temperature at which natural gas is saturated with water vapor at any given pressure.
A. dew point temperature B. maximum load temperature C. saturation carryover
20. The process by which heat travels through a substance is:
A. radiation B. conduction C. separation
21. Cut point changes can be made in a distillation column by:
---A. changing the reflux rate
B. changing the feed temperature C. changing the reboiler temperature D. changing any of the above
22. What happens when the heat balance inside a distillation column is adjusted?
---A. Product composition changes
B. More of one product and less of another will be made C. Both A and B are correct
23. If we increase the reflux rate in a crude distillation unit and hold other operating conditions constant, which of the following will occur? ---
A. Lighter overhead, bottom, and side draw products B. Heavier overhead and side draw products
C. Heavier bottom product D. More overhead product
24. If we increase the feed temperature in a crude distillation unit and hold other tower variables constant, which of the following will occur?
---A. Heavier overhead, bottom, and side draw products B. Less bottom product
C. More overhead product D. All of the above
25. Opening a stripper draw makes this product and products below this tray: ---
A. heavier B. lighter
C. Does not affect the stripper draw product
26. What happens to the boiling point of a liquid when pressure against those liquids
increased?---A- The boiling point temperature is increased.
C- The boiling point dose not change unless the vapor pressure of that liquid changes.
D- It depends whether the liquid is water or a mixture of Hydrocarbons.
27. What happens on each tray as a result of vapor -liquid contact?
---A- Light materials in the liquid tend to condense, and heavy materials in the vapor tend to vaporize.
B- Light materials in the liquid tend to vaporize, and heavy materials in the vapor tend to condense.
28. Good fractionation requires---.
A- A tower with a large number of trays. B- A multiple feed-port tower.
C- Multi-pass down comers.
D- Good vapor-liquid contact on each tray.
29. When we heat a mixture of Hydrocarbons, the first molecules to boil and vaporize are---.
A- The heavy or large Hydrocarbons.
B- The light or small Hydrocarbons.
C- The medium-sized Hydrocarbons.
D- None of the above. They all start boiling at the same temperature.
30. Which of the following can generate the most heat to vaporize
feed?---A- Condenser B- Heat exchanger
Question No.2: Answer the following questions
2. Identify the function of rectifying section in the tower.---
2. Identify the function of stripping section in the tower.
---3. Identify the function of flash zone in the tower.
---
4. List the kinds of reboilers used to heat the bottom product in the tower.
---6. What is meant by “reflux”? and list four (4) kinds of reflux.
---7. Explain the purpose of heating up the bottom product.
---
8. List four (4) reasons for tower flooding.
---
9. List four (4) factors that affect emulsion treating. -
---Question N0. 3: What is meant by the following terms?
1- Demulsifies
Demulsifies are materials that act to neutralize the effect of emulsifying agents, and are surface-active agents.
2- Latent Heat
The quantity of heat that required to change the phase of material from liquid to gas or from gas to liquid at constant temperature and a given pressure.
3-Emulsifing Agent
An emulsifying agent is a substance that promotes the formation and stability for emulsion has a surface-active behaviour.
4- Dehydration
Dehydration is the process of removing water from a substance.
5- Stripping section in the tower
The lower section of the tower below the flash zone and used to improve top product quantity.
6- Rectifying section in the tower
The upper section of the tower above the flash zone and used to improve top product quality.
7. Reflux ratio
8. Equilibrium stage
9. Distillation
