Ch. 7 Flashcards
1
Q
- When furnace draft is maintained at atmospheric pressure (or just below), the draft is referred to as:
a. Natural draft
b. Forced draft
c. Induced draft
d. Balanced draft
e. Negative draft
A
d. Balanced draft
2
Q
- Natural draft is the difference in pressure caused by:
a. The height of the furnace
b. The temperature in the furnace
c. The diameter of the stack
d. The atmospheric air conditions
e. The height of the stack
A
e. The height of the stack
3
Q
- Advantages of mechanical draft are:
1) Better purging of boiler
2) Less expensive stack can be used
3) Less supervision during operation
4) Increases unit efficiency
a. 1, 2
b. 1, 2, 3
c. 1, 2, 4
d. 2, 3, 4
e. 1, 4
A
c. 1, 2, 4
4
Q
- Disadvantages of mechanical draft are:
1) Higher initial cost
2) Closer supervision is required
3) More expensive stack must be used
4) Draft is dependent on atmospheric conditions
a. 1, 4
b. 1, 3
c. 2, 3
d. 3, 4
e. 1, 2
A
e. 1, 2
5
Q
- Draft is a term that indicates:
a. Atmospheric pressure
b. Static pressure
c. Absolute pressure
d. Friction pressure
e. Gauge pressure
A
b. Static pressure
6
Q
- In a boiler duct, pressure drop through a restriction is used to:
a. Measure the draft
b. Measure the air flow
c. Measure the density
d. Measure the secondary air pressure
e. Measure air temperature
A
b. Measure the air flow
7
Q
- The instruments used to monitor the air and flue gas system in a boiler consist of instruments that measure:
1) Pressure
2) Temperature
3) Density
4) Flow
a. 1, 2, 3
b. 1, 2, 4
c. 1, 3, 4
d. 1, 2, 3, 4
e. 2, 3, 4
A
b. 1, 2, 4
8
Q
- Draft is measured in:
a. mm of wg
b. mm of mercury
c. cm of mercury
d. cm of wg
e. kPa
A
d. cm of wg
9
Q
- A simple gauge for measuring draft consists of a glass U-tube containing water. This type of gauge is known as a _________.
a. manometer
b. orsat
c. pressure tube
d. diaphragm
A
a. manometer
10
Q
- A type of gauge that has superseded the U-tube for measuring boiler draft is the ________ gauge.
a. manometer
b. orsat
c. pressure tube
d. diaphragm
A
d. diaphragm
11
Q
- The __________ fan provides the volume of combustion air to the boiler.
a. induced draft
b. forced draft
c. cross draft
d. balanced draft
A
b. forced draft
12
Q
- The __________ fan is used to remove the hot flue gases from the boiler.
a. induced draft
b. forced draft
c. cross draft
d. balanced draft
A
a. induced draft
13
Q
- Draft in a furnace depends on:
1) The temperature of atmospheric air
2) The height of the stack
3) The pressure in the furnace chamber
4) The temperature of the gases in the stack
a. 1, 2, 3
b. 1, 2, 4
c. 2, 3, 4
d. 1, 2, 3, 4
e. 1, 3, 4
A
b. 1, 2, 4
14
Q
- Draft fans can be divided into the following types:
1) Backward curved blade
2) Air foil curved blade
3) Straight blade
4) Forward curved blade
a. 1, 4
b. 1, 2, 3
c. 2, 3, 4
d. 1, 2, 3, 4
e. 1, 3, 4
A
d. 1, 2, 3, 4
15
Q
- Draft fan output is controlled by:
1) Variable speed
2) Inlet damper control
3) Outlet damper control
4) Variable area for blades
a. 1, 2, 3
b. 1, 3, 4
c. 2, 3, 4
d. 1, 2, 3, 4
e. 1, 2, 4
A
a. 1, 2, 3