Ch. 1 Flashcards
1
Q
- Packaged watertube boilers capacities range from?
a. 2300 kg to 65000 kg per hour
b. 500 kg to 100 mg per hour
c. 15 psi to 15000 kg per hour
d. 65000 to 100000 kg per hour
A
a. 2300 kg to 65000 kg per hour
2
Q
- The main advantage of the packaged boiler is its _____ _____.
a. small size
b. compact design
c. low cost
d. quality steam
A
c. low cost
3
Q
- Field erected boilers have outputs of?
a. 75000 kg/h
b. 100000 kg/h
c. 100 mg/h
d. 150000 kg/h or more
A
d. 150000 kg/h or more
4
Q
- One square metre of heating surface equals 10 kilowatts. The heating surface of a boiler must be determined by computing the area of the surface involved in square metres and where a computation is to be made of a curved surface; the surface having the greater radius shall be taken.
a. True
b. False
A
a. True
5
Q
- Where electric power is used as the heating source, the boiler rating shall be the maximum kilowatt rating of the ______ ______.
a. power plant
b. heating element
c. boiler wiring
d. MCC
A
b. heating element
6
Q
- Where the boiler provides the entire steam supply to an electric generating unit, the output of the boiler is expressed in terms of power output of the generator (for example a 300 megawatt boiler).
a. True
b. False
A
a. True
7
Q
- The downcomers are located in the ______ regions of the boiler, or external to the furnace altogether. The risers are located in the ________ zones of the boiler, being exposed to radiant heat of the furnace or to the very hot flue gases near the furnace.
a. back, front
b. cooler, hottest
c. water, furnace
d. drum, radiant
A
b. cooler, hottest
8
Q
- Most downcomers run horizontally between the steam drum and the mud drum.
a. True
b. False
A
b. False
9
Q
- The steam separating equipment separates the _______ from the steam/water mixture.
a. water
b. steam
c. impurities
d. water droplets
A
b. steam
10
Q
- There are several factors that influence the natural circulation in a watertube boiler. These are:
a. The height of the steam drum above the bottom drum or header.
b. The amount of heat applied to the tube. The hotter the tube becomes, the more steam bubbles are formed, creating more mass differential and thus more circulation.
c. The operating pressure of the boiler. As boiler pressures increase, the density of the steam increases
d. The cleanliness of the tubes can also affect circulation.
e. All of the above
A
e. All of the above
11
Q
- The purpose of the downcomer is to supply:
a. Hot water to the steam drum
b. Cool water to the steam drum
c. Cool water from steam drum to rest of boiler
d. Steam to steam drum
e. Boiler feed water to the boiler
A
c. Cool water from steam drum to rest of boiler
12
Q
- These types of boilers (A, D, and O) have furnaces cooled by _________ lining the furnace walls.
a. watertubes
b. fans
c. desuperheaters
d. air circulation
A
a. watertubes
13
Q
- In the A, D & O type boiler steam bubbles form in the hottest tubes and rise to the steam drum, where the steam is separated out of the water and steam mixture. Circulation is maintained by water returning to the mud drum through the cooler tubes. The hotter tubes, risers, are the ones in the radiant area of the furnace and the hottest areas of the generating bank of tubes.
a. True
b. False
A
a. True
14
Q
- A steam generating unit consists of a number of elements all of which contribute to the production of steam. The elements of a typical steam generator include:
1) Boiler
2) Superheater
3) Ash removal equipment
4) Reheater
5) Economizer
6) Steam piping
7) Air heater
8) Fuel equipment
9) Draft fans
a. 1, 2, 7, 8, 9
b. 1, 2, 4, 5, 7, 8, 9
c. 3, 4, 6, 7, 8
d. 1, 2, 3, 4, 5, 7, 8, 9
A
d. 1, 2, 3, 4, 5, 7, 8, 9
15
Q
- In steam generating units the feed-water entering the boiler section first passes through the __________ section where it is heated by the combustion gases leaving the boiler.
a. furnace
b. economizer
c. boiler drum
d. superheater
A
b. economizer
16
Q
- Combustion air for the burners is preheated to ______in the air heater section by combustion gases leaving the economizer section.
a. 150 °C
b. 100 °C
c. 350 °C
d. 500 °C
A
c. 350 °C
17
Q
- Generally two types of draft fans are used. A _____ ____ fan supplies air to the air preheater. The preheated air (350°C) for combustion goes to the coal pulverizers and to the burners. An ______ ____ fan exhausts the combustion gases (170°C) from the air heater to the stack.
a. center mounted, external mounted
b. forced draft, induced draft
c. induced draft, forced draft
d. turbine draft, ejection draft
A
b. forced draft, induced draft
18
Q
- Natural circulation in a boiler depends upon the ___________ in the density of a column of water and the density of a column containing a steam/water mixture.
a. amount
b. mass
c. difference
d. density
A
c. difference
19
Q
- The difference in density between water and saturated steam becomes progressively less with increased pressure and disappears altogether at the critical pressure _______ .
a. 22106 kPa
b. 15000 kPa
c. 10000 kPa
d. 25000 kPa
A
a. 22106 kPa
20
Q
- Steam generators operating above critical pressure are said to be ______-critical and steam generators operating below critical pressure are classed as ____-critical.
a. sub , super
b. super, sub
c. normal, pre
d. high, low
A
b. super, sub
21
Q
- The advantage of forced circulation in a boiler is a _________ flow in all tubes.
a. negative
b. greater
c. positive
d. mass
A
c. positive
22
Q
- The disadvantages of forced circulation in a boiler are the ______ _____ of equipment, pumps, piping, etc.
a. greater use
b. increased costs
c. higher maintenance
d. numbers of
A
b. increased costs
23
Q
- The main feature of a Controlled Circulation Boiler is a (circulating) pump, which is used to provide circulation.
a. True
b. False
A
a. True
24
Q
- Not all Once-through boilers use forced circulation.
a. True
b. False
A
b. False
25
181. The arrangement of a once through boiler has no drums. The feed water is heated and then evaporated and superheated in ______ ______ through the unit.
a. two passes
b. one passage
c. 3 passes
d. 4 passes
b. one passage
