Steam

Question 1

What is a liquid?

Answer 1

It is a fluid that is characterized by free movement of the molecules among themselves, but without the tendency to separate.

Question 2

What is a gas?

Answer 2

It is a fluid that does not have either independent shape or volume, but has a tendency to expand indefinitely.

Question 3

What is a vapor?

Answer 3

It is a fluid that may be condensed (to a liquid) as a result of either (1) a pressure increases at constant temperature, or (2) a temperature decrease at constant pressure.

Question 4

What is a mole?

Answer 4

It is equal to the atomic mass number, in grams, of

that element. 6.022 x 10^23 atoms x AMU/atom x g/AMU

Question 5

State Charles’ Law.

Answer 5

At low pressures, the volume of a gas at constant pressure is directly proportional to the absolute temperature of the gas. V1/T1 = V2/T2

Question 6

State Boyle’s Law

Answer 6

At low pressures, the volume of a gas at constant temperature is inversely proportional to the absolute pressure of the gas. P1V1 = P2V2

Question 7

What is the formula for the Ideal Gas Law?

Answer 7

PV = nRT

Question 8

What is the formula for the Ideal Gas Law?

Answer 8

PV = nRT. 
P = absolute pressure (psia)
V = volume (ft3)
n = number of moles
R = universal or ideal gas constant (atm liters / mole °K)
T = absolute temperature (°K)

Question 9

When can Ideal Gas Laws be applied to real gases?

Answer 9

Though no such gas exists, the fact that a real gas behaves approximately like an ideal gas provided a specific target for theories for the gaseous state. Monatomic gas behavior is very similar to ideal gases and can be described very accurately using the Ideal Gas Law. Accuracy will decrease with diatomic and polyatomic gases such as oxygen (O2) and carbon dioxide (CO2). Also, as gas pressure increases, the
accuracy decreases.

Question 10

Explain the usefulness of Steam Tables to the Control Room Operator.

Answer 10

Operators use steam tables to verify plant instrumentation and examine equipment performance. Steam tables allow the operator to have additional
information of plant conditions, for example,
determining the exact steam temperature from pressure readings. These tables give the various properties of steam at a given state point, which is usually fixed by the measured properties of temperature or pressure.

Question 11

Apply Boyle’s Law, Charles’ Law, the Combined Gas Law and the Ideal Gas Law in solving gas or mixture problems.

Answer 11

Review examples.

Question 12

Apply saturated and superheated steam tables in solving liquid-vapor problems.

Answer 12

Review examples.

Question 13

List the advantages of using steam as a working fluid.

Answer 13

It is abundant, has a high specific heat capacity, and a high critical temperature.

Question 14

Identify the regions and lines on a typical P-T diagram.

Answer 14

The three regions of it correspond to the solid, liquid, and gas phases. The three phase curves, called the Sublimation, Fusion, and Vaporization Lines clearly divide the three phases. Sublimation Line represents values of
pressure and temperature at which a substance can exist as both a solid and gas in equilibrium. The Fusion Line represents values of pressure and temperature at which a substance can exist as both a liquid and solid in equilibrium.

Question 15

Define the Latent Heat of Vaporization.

Answer 15

The change in specific enthalpy which must occur for a substance at a given pressure and temperature to change phase from a liquid to a gas.

Question 16

Define the Vaporization Line.

Answer 16

The point at which a substance can exist as both a liquid and a gas in equilibrium.

Question 17

Define Critical Point.

Answer 17

The highest temperature and pressure at which a pure material can exist in vapor/liquid equilibrium as distinguishable phases.

Question 18

Define Vapor Dome.

Answer 18

The region on a property diagram bounded by the Saturated Liquid and Saturated Vapor Lines.

Question 19

Define Isotherm.

Answer 19

The lines of constant temperature on a property diagram.

Question 20

Define Saturated Liquid.

Answer 20

A liquid in a state such that the addition of heat will result in the formation of vapor.

Question 21

Define Wet Vapor.

Answer 21

A mixture of saturated liquid and saturated vapor.

Question 22

Define Saturated Vapor.

Answer 22

A vapor in a state such that the removal of heat will result in condensation.

Question 23

Define Vapor Pressure.

Answer 23

The pressure of a fluid at which the liquid and vapor phases are in equilibrium for a given temperature.

Question 24

Define Moisture Content.

Answer 24

The mass of liquid divided by the mass of vapor and liquid mixture.

Question 25

Define Quality.

Answer 25

The mass of vapor divided by the mass of vapor and liquid mixture.

Question 26

Define Superheated Vapor.

Answer 26

A moisture free gas existing within the vapor dome as the result of a rapid pressure decrease and expansion.

Question 27

Define subcooled liquids.

Answer 27

The difference between the actual temperature of a liquid and its saturation temperature at a given pressure, or the difference in a liquids specific enthalpy and its saturation specific enthalpy.

Question 28

Define compressed liquids.

Answer 28

A liquid existing at a pressure above its saturation pressure for its temperature.

Question 29

Define subcooling.

Answer 29

The difference between the actual temperature of a liquid and its saturation temperature at a given pressure, or the difference in a liquids specific enthalpy and its saturation specific enhalpy.

Question 30

Define Specific Heat.

Answer 30

The quantity of heat required to raise the temperature of one pound mass of a substance one degree (Btu/lbm °F).

Question 31

Identify the following terms on a T-s diagram:

a. Critical point
b. Triple point line
c. Saturated liquid line
d. Saturated vapor line
e. Solid, liquid, gas, vapor, and fluid regions

Answer 31

Review pages 25 and 26 of lesson plan.