Week 12 of 15 – Terms	Name: Answer Sheet

In your own words, write a definition for each of the following terms. Plagiarism will be checked and not tolerated.

Points: 5 pts/each = 11 * 5 = 55 pts

Distillation column

A collection of still stacked one on top of another; separates chemical mixtures by boiling points. Distillation columns fall into two distinct classes: plate and packed.

Cascade control

1. Control action in which the output of one controller is the set point for another controller. [ANSI/ISA-77.42.01-1999] 2. A control system composed of two loops where the set point of one loop (the inner loop) is the output of the controller of the other loop (the outer loop). 3. A control technique that incorporates a master and a slave loop. The master loop controls the primary control parameters and establishes the slave-loop set point. The purpose of the slave loop is to reduce the effect of disturbances on the primary control parameter and to improve the dynamic performance of the loop.

Catalyst regeneration system

A process system for renewing a catalyst or making it reusable after it has accumulated reaction residues such as coke. Examples of regeneration processes include passing steam over the catalyst bed or burning off the carbon residue.

Catalyst

A chemical that can increase or decrease a reaction rate without becoming part of the product. Catalysts are classified as adsorption, intermediate, inhibitor or poisoned.

Slurry

1. A suspension of fine solids in a liquid that can be pumped or can flow freely in a channel. 2. See slip. 3. A semiliquid refractory material that is used to repair furnace linings. 4. An emulsion of soluble oil and water that is used as a cutting fluid in certain machining operations.

Slurry with suspended particles

A suspension of solid particles in a slurry that are not soluble.

Reboiler

The heat exchanger at the bottom of a distillation column. The reboiler generates the vapors that ascend through the column from liquid that comes down the column. The term is derived from “re-boil.”

Second-order lag

A second order system is that whose output is modeled by a second order differential equation. Sources of second order dynamics come from a series of first-order systems, or a processing system with a controller.

Three element feed water regulator

A three element feed water regulator relates to a means to provide automatic protection against damage to a boiler feed pumps. More particularly the regulator contemplates the control of the delivery of feedwater from the boiler. Feed pump in such a manner as to substantially preclude the possibility of reducing the available net positive suction head at the suction of the boiler feed pump taking its suction from a direct contact heater supplied with steam from a bleed stage of the main turbine.

Multivariable control

A control system that involves several measured and controlled variables and in which the interdependences are considered when calculating the output variables.

Decoupler in control systems

A technique in which interacting control loops are automatically compensated when any one control loop takes a control action.