Distillation Unit 1

The gaseous state of a substance that usually exists as a liquid at ordinary temperature and pressure is called a _________________.

-vapor

The amount of vapors flowing up a distillation tower is called the _________________.

-vapor rate

The process of changing a liquid into a vapor by applying heat is called (a) _________________. The process of changing a vapor into a liquid by removing heat is called (b) _________________.

-vaporization -condensation

The height that a liquid reaches on a tray before flowing down to the next lower tray is determined by a _________________.

-weir

T/F. A successive batch distillation system differs from a single batch system in that it distills many batches of mixture instead of just one.

False

T/F. Increases in pressure at both the top and the bottom of a distillation tower may indicate flooding.

False

T/F. Like any other tower, a stripper has both a rectification section and a stripping section.

False

T/F. The proper pressure in a distillation tower is whatever pressure corresponds with the boiling point of the liquid mixture.

False

T/F. The trays in a vacuum tower have a similar diameter and are not as far apart as the trays in a regular tower.

False

T/F. A decrease in pressure at the top of a distillation tower and an increase in pressure at the bottom of the tower indicate a high feed rate.

True

T/F. A single batch system is designed to distill a fixed amount of liquid mixture.

True

T/F. Correct temperatures are important to the distillation process because mixtures will only separate properly if the boiling range of each desired product is maintained

True

T/F. If pressures are not maintained at a steady value, a distillation tower will not produce a constant flow of vapors coming off the top.

True

T/F. In many side-draw towers, a portion of the liquid overflow from each side-draw may be reintroduced into a lower tray as reflux.

True

T/F. In some distillation towers, the reboiler functions not only to boil off entrained overhead product, but also to supply the major portion of the heat necessary to make the distillation process work.

True

T/F. The primary physical reaction involved in distillation is changes of state of matter.

True

T/F. The temperature gradient can be increased by applying heat to the bottom of the tower with the reboiler and by cooling the top of the tower with reflux.

True

T/F. Two methods used to control overlap in a distillation tower are reboiling and refluxing.

True

Which of the following is NOT a difference between a side-draw tower and a tower designed to separate a binary mixture? a. A side-draw tower has draw-off pipes located at various trays along the side of the tower. b. A side-draw tower can separate mixtures into more than two products. c. A side-draw tower uses strippers d. All of the above are differences between side-draw towers and towers designed to separate binary mixtures.

-All of the above are differences between side-draw towers and towers designed to separate binary mixtures.

Which of the following statements in NOT true? a. The temperature at the feed point of a distillation tower should be the boiling point of the feed mixture. b. If the temperature at the feed point of a distillation tower is higher than boiling point of the feed mixture, not enough of the overhead product will vaporize. c. The temperature at the top of a distillation tower should be the boiling point of the desired overhead product. d. If the temperature at the top of a distillation tower is too low, not enough of the overhead product will vaporize.

-If the temperature at the feed point of a distillation tower is higher than boiling point of the feed mixture, not enough of the overhead product will vaporize.

Which of the following is NOT a reason for using vacuum distillation? a. Some products in a mixture may decompose or become damaged at high temperatures. b. Products always separate better under vacuum distillation. c. Some liquids will only vaporize at very high temperatures, and running a tower at very high temperatures would use too much energy. d. Tower materials do not have to be specially constructed for high-temperature operation.

-Products always separate better under vacuum distillation

The section above the feed tray in a distillation tower is called the (a) _________________ section; the section below the feed tray is called the (b) _________________ section.

-Rectifying, or fractionating -Stripping

Which of the following statements is NOT true? a. The temperature at the bottom of a distillation tower should be the boiling point of the bottoms product. b. If the temperature at the bottom of a distillation tower is too high, more of the bottoms product will vaporize and move up the tower instead of remaining a liquid. c. If the temperature at the bottom of a distillation tower is too low, some overhead product will remain entrained in the bottom instead of vaporizing and moving up. d. The temperature in the reboiler should be a little higher than the temperature of the desired bottoms product.

-The temperature in the reboiler should be a little higher than the temperature of the desired bottoms product.

The purpose of _________________ in some distillation towers is to force rising vapors to bubble through liquid that has condensed on a tray.

-bubble caps

The temperature at which a product of a distillation operation is considered acceptable is called the _________________ point.

-effective cut

The two places where pressure is important in a distillation system are in the (a) _________________ and the (b) _________________.

-feed tank -distillation tower

The energy of molecules in motion is called _________________ energy.

-kinetic

The vapor that is collected and condensed in a single batch system is called the (a) _________________, or lighter product. The liquid left behind is called the (b) _________________, or heavier product.

-overhead product -bottoms product

An incomplete separation is called an _________________.

-overlap

The (a) _________________ rate is the amount of liquid pumped back into the top of a distillation tower from the condenser; the (b) _________________ rate is the amount of vapors reintroduced into the tower from the liquid returning from the reboiler.

-reflux -boil-up

Heat that can be sensed and measured by a thermometer is called (a) _________________ heat. Heat that cannot be measured by a thermometer, but is associated with change of state, is called (b) _________________ heat

-sensible -latent