Chapter 15 Distillation Systems

Condensed water vapor is purer than the original mixture because most of the salts, minerals, and impurities do no vaporize at what temperature? (Hint: The boiling point of water.)

212 Degress

Dew Point Curve

Is the upper curve on a vapor liquid equilibrium curve and is defined as the temperature where the first drop of liquid forms.

Overloading

Operating a column at max conditions.

Bottoms Product

Residue; the heavier components of the distillation process fail to the bottom of the tower and are removed.

Fractional Distillation

Separation of two or more components through distillation.

Entrainment

The upward movement of high velocity, large vapor droplets in a distillation column.

What is oldest distillation process? Continuous or Batch?

Batch

What are the tree basic designs of a Plate Column?

Bubble-Cap, Sleve and Valve Tray

Packed columns are designed for pressure drops between _.__ and _.__ .inch of water per foot of packing medium.

0.20 and 0.60 inch of water per foot of packing medium

What is the boiling point of water?

100°C and 212°F

Valve Trays

A small round metal disc with three or four legs called risers that allow the valve to lift as hot vapors push through the valve tray. Designed to enhance vapor liquid contact in a plate column.

Feed Distrubutor

A device used in a packed column to evenly distribute the liquid feed.

Bubble Cap Trays

A fixed cylindrical tube and cap mounted vertically to a horizontal tray designed to enhance vapor liquid contact in a plate column.

Azeotropic mixture

A mixture of two or more components that boil at similar temperatures and at a certain concentration. The liquid and vapor concentrations of an azeotrope are equal.

Total Reflux

A process where the feed to the column is stopped and the total amount leaving the column from the top, sides, or bottom is returned to the column.

Reflux

Condensed distillation column product that is pumped back to increase product purity and control temperature.

What systems does a Distillation process include?

Feed System, Preheat System, Overhead system, and the Bottom System.

Name the basic components of a plate column.

Feed Inlet, Feed Tray, Rectifying or Enriching Section, Stripping Section, Sidestream Outlets, Downcomer, Weir, Riser, Control Loops, Pipes, Pumps, Valves, Instrumentation, and computers.

The condensate is referred to as what?

Distillate

During tower operation, raw materials are pumped to a feed tank and mixed thoroughly. Part of the mixture vaporizes as it enters the column, while the rest of the mixture does what?

Drops into the lower sections of the tower.

Local Flooding

Excessive liquid flowing down a column blocks vapor flow up the column in one section.

In the history of distillation what were the three operations of a distillation column in order.

First was batch, second was continous batch, and now we use fractional distillation.

Bonus! Which is faster Hot or Cold?

Hot (You can easily catch a cold.) Good luck on the test!

Overlap

Incomplete separation of a mixture.

Initial Boiling Point

Is often described as the temperature where the mixture first starts to boil or evolve vapors.

Bubble Point Curve

Is the lower curve on a vapor liquid equilibrium curve and identifies the specific temperature where the mixture first produces vapor.

Overall Flooding

Local flooding expands to the entire column

Tray Drying

Occurs due to low feed rates, low reflux rates, or high upward vapor flow rates from tray to tray.

Downcomers

Occurs when the liquid flow rate in the tower is so great that liquid backs up in the downcomer and overflows to the upper tray. Liquid accumulates in the tower, differential pressure increases, and product separation is reduces.

Weeping

Occurs when the vapor velocity is too low to prevent liquid from flowing through the holes in the tray instead of across the tray. Differential pressure is reduced and product separation is reduced.

What two things does a Reboiler help control?

Overlap and Heat Balance

What are the two types of distillation columns?

Packed and Plate

What are the differences in a packed column and a plate column?

Packed columns are filled with packing material to enhance vapor liquid contact. Plate columns use trays stacked on top of each other.

Each section in a trayed or packed column will have its own individual footprint or characteristics? What are these characteristics?

Pressure, Temperature, Composition, Velocity and Performance

Preheating Systems are designed to do what in the Distillation process?

Raise the temperature of raw feedstock before it enters the distillation column.

What are the three types of Packed Distillation Columns?

Random, Structured, and Stacked.

Overlap can be controlled or limited by returning part of the overhead product to the tower. What is this process called? What is product being returned called?

Refluxing and Reflux

Liquid that does not vaporize in a column is called what?

Residue

A Distillation Column is built on what principal?

That light and heavy molecules have different boiling points.

Heat Balance states what?

That the heat that goes into a distillation column must be equal to the heat that goes out of it. Maintaining this balance is critical to the proper functioning of the tower.

What does the Material Balance Theory state?

That the sum of raw materials entering must equal the total of the products leaving the distillation tower.

Reflux Ratio

The amount of reflux returned to the tower divided by the amount of overhead product sent to storage.

Reflux Ratio

The amount of reflux returned to the tower divided by the amount of overhead product sent to storage. For example, 120 GPM reflux\ 60 GPM overhead to product tank = 2:1 reflux ratio.

Boil Up Rate

The balance of the products returned to the column from the kettle reboiler.

Distillate

The condensate taken from a distillation column.

Vapor Pressure

The outward force exerted but he molecules suspended in vapor state above a liquid at a given temperature; when the rate of liquefaction is equal to the rate of vaporization.

Vacuum Distillation

The process of vaporizing liquids at temperatures lower than their boiling point by reducing pressure.

Temperature Gradient

The progressively rising temperatures from the bottom of a distillation column to the top.

Distillation

The separation of components inna mixture by their boiling points.

Rectification

The separation of different substances from a solution by use of a fractionating tower.

McCabe Thiele

The simplest method used in the analysis of binary distillation. The composition of the mixture on each theoretical tray can be determined by the mole fraction of one of the components.

Boiling Point

The temperature at which a liquid changes to a vapor.

Bubble Point

The temperature at which a liquid mixture begins to boil and produce vapor.

Dew Point

The temperature at which a mixture produces the first drop of liquid on a vapor liquid equilibrium curve.

Preheat is used to avoid ______________ _________________ and improve productivity.

Thermal Shock

What is the purpose of a Vacuum System?

They lower the boiling point of a substance, enhance the molecular escape of molecules from the surface of liquid, reduce energy cost, reduce molecular damage by overheating, and reduce equipment damage.

A heat exchanger that is used to convert the entire overhead vapor to liquid is called a what?

Total Condenser

Lighter components move _____________ and heavier components move______________.

Up, Down

Vapor-Liquid Equilibrium diagram

Used to help a technician understand phase behavior of a two component mixture.

Inside a Distillate Column, _____________ affects the boiling point of a substance in the opposite way that positive pressure does.

Vacuum

What type of tower offer an excellent option in situations that normally would require high temperatures.

Vacuum Tower

Sieve Trays

a flat, thin plate with small holes in it mounted on a horizontal tray designed to enhance vapor-liquid contact in a plate column

Packed Tower

a tower that is filled with specialized packing material instead of trays.

Binary mixtureterm-23

contains two or more components.

Tray Columns

devices located on a tray in a column that allow vapors to come into contact with condensed liquids; three basic designs are bubble-cap sieve, and valve.

Downcomer Flooding

occurs when the liquid flow rate in the tower is so great that liquid backs up in the downcomer and overflows to the upper tray. Liquid accumulates in tower, differential pressure increases, and product separation is reduced.

Puking

occurs when the vapor is so great that it forces liquid up the column or out the overhead line.

Jet Flooding

occurs when the vapor velocity is so high that liquid down flow in the tower is restricted. Liquid accumulates in the tower, differential pressure increases, and product separation is reduced.

Foaming

often the result of too much heat, impurities in the feed, or active turbulence on the trays above undersized downcomers.

Cryogenic Distillation

often used to separate oxygen and nitrogen from our atmosphere by using low-temperature drying and distillation methods.

Feed Tray

point of entry of process fluid in a distillation column, under the feed line.

Heat Balance

principle that heat in equals heat out.

Material Balance

principle that the sum of the products leaving equals the feed entering the distillation column.

Column Loading

the amount of material fed continuously into a distillation column.

Partial Pressures

the amount of pressure per volume exerted by the various fractions in a mixture of gases.

Relative Volatility

the characteristics associated with a liquid's tendency to change state or vaporize inside a distillation system.

Overhead Product

the lighter components in a distillation column, which rise through the column and go out the overhead line, where they are condensed.

Stripping Section

the section of a distillation column below the feed line, where heavier components are located.

Final Boiling Point

the temperature at which the heaviest component boils.

Rectifying Section

the upper section of a distillation column (above the feed line), where the higher concentration of lighter molecules is located.

Ternary Mixture

three components in a mixture