SEPA Flashcards
Theoretically, what is the number of equilibrium stages in distillation operating at total reflux?
minimum
This physical model for separation represents a device in which two incoming streams come in contact and attain equilibrium before leaving the device.
equilibrium stage model
In steam distillation, separation occurs at a temperature that is ____ the boiling point of water and ____ the boiling point of the main component of the other (immiscible) phase.
below … below
The optimum reflux ratio in distillation is approximately ___ times the minimum reflux ratio.
1.1 to 1.5
In the design of a stagewise distillation column using McCabe-Thiele method, what does a horizontal feed line indicate?
a saturated vapor feed
Which of the following parts of a distillation column cannot be considered an equilibrium stage?
a total condenser
In distillation, which of the following occurs as a consequence of increasing the reflux ratio?
the distillate product decreases
Which of the following uses both energy and material separating agents?
steam distillation
Which of the following distillation methods is used in petroleum refining, i.e., to make rough separation of high- and low-boiling components of crude oil?
flash distillation
Which of the following is not a membrane separation process?
reverse osmosis
pervaporation
extractive distillation
electrodialysis
extractive distillation
Which of the following membrane separation processes best applies for the separation of azeotropic mixtures?
pervaporation
Which of the following is the expected consequence of increasing the liquid-to-gas ratio in a countercurrent gas absorption column while keeping the other conditions constant?
The operating line shifts away from the equilibrium curve
In a countercurrent gas absorber design analysis, both the operating and equilibrium line are linear. The inlet liquid composition and exit gas composition are maintained constant. In order to increase the absorption factor, we should
decrease the slope of the equilibrium line
Which of the following arrangements cannot be considered a stage?
Three streams of different compositions are fed to a large stirred tank. The product mixture consists of two immiscible phases that are withdrawn from the tank separately.
Water and salt crystals are fed separately into a stirred tank. The salt dissolved completely, and the product solution is withdrawn at the same rate as the water and salt are added.
Crushed soybeans are fed to an agitated tank. An organic solvent is also introduced into the tank, where it is dissolved the oil from the beans. The oil-solvent solution flows from the top of the tank and the oil-free beans are removed at the bottom.
Air bubbles up through a hot water in a column. The air emerging from the surface of the water is saturated with water vapor.
Water and salt crystals are fed separately into a stirred tank. The salt dissolved completely, and the product solution is withdrawn at the same rate as the water and salt are added.
Percolation is a separation process that adopts the same principles as that of
leaching
In the McCabe-Thiele method of distillation design, a constant molal overflow is assumed. This condition is valid when the following assumptions are made:
constant heat capacity and negligible heat of mixing
Which of the following can be actual stages in a vertical column for gas-liquid or vapor-liquid contacting (e.g., distillation, gas absorption)?
plates
Which of the following is true?
The pressure drop in conventional tray or plate columns is less than that packed columns.
Channeling is more commonly encountered in tray columns than in packed columns.
Packed columns are generally larger tray or packed columns.
The separation of mixtures with a corrosive component is best done in packed columns than in tray or plate columns.
The separation of mixtures with a corrosive component is best done in packed columns than in tray or plate columns.
At which conditions do we use the McCabe-Thiele method in the analysis of stagewise separation processes such as distillation and gas absorption?
negligible heat of solution, constant heat capacity, steady-state
