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
2300 kg to 65000 kg per hour
Packaged boilers main advantage compared to Shop & Field Erected boilers is ____?Assembly Time
a. Quality
b. Efficiency
c. Low Cost
d. Quality Steam
low cost
When calculating the output or rating of a boiler one square meter of heating surface equals ____ kilowatts
(a) 1000
(b) 10
(c) 15
(d) 100
10
Field erected boilers have outputs of?
D. 150000 kg/h or more
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. True
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
Heating element
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. True
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
cooler, hottest
Most downcomers run Horizontaly between the steam drum and the mud drum.
a. True
b. False
b. False
The steam separating equipment separates the _______ from the steam/water mixture.
D. steam
There are several factors that influence the natural circulation in a watertube boiler. These are:
E. All of the above
The purpose of the downcomer is to supply:
D. Cool water from steam drum to rest of boiler
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.
B. difference
These types of boilers (A, D, and O) have furnaces cooled by _________ lining the furnace walls.
B. watertubes
In the economizer section the feed-water is normally heated to within ____ of the boiler water temperature.
(C) 20 degree
In the reheater section, the temperature of the steam is raised to approximately the original superheat temperature ____.
(A) 538 Degree
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. water conditioner
4. reheater
5. economizer
6. steam piping
7. air heater
8. fuel equipment
9. draft fans
B. 1, 2, 4, 5, 7, 8, 9
Feed-water entering the boiler section first passes through the __________ section where it is heated by the combustion gases leaving the boiler.
B. economizer
Combustion air for the burners is preheated to ______ in the air heater section by combustion gases leaving the economizer section.
C. 350 °C
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.
B. forced draft, induced draft
Steam Generators operating above ___are said to be super critical
(B) Critical Pressure
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
Steam generators operating above critical pressure are said to be ______-critical and steam generators operating below critical pressure are classed as ____-critical.
A. super, sub
The advantage of forced circulation in a boiler is a _________ flow in all tubes.
B. positive
The disadvantages of forced circulation in a boiler are the ______ _____ of equipment, pumps, piping, etc.
D. increased costs
The arrangement of a once through boiler has no drums. The feed water is heated and then evaporated and superheated in ______ ______ through the unit.
