POWER ENGINEERING 2A3 EXAM QUESTIONS AND
CORRECT ANSWERS| 2026 UPDATED
One boiler horsepower is equal to how many kW
9.809kW
This is still the common measure of capacity for small boilers, where large boiler
capacity is given in the number of kg of steam per hour.
What are the definitions of boiler, steam generator and steam generating unit?
Boiler - strictly speaking are the elements in which the change of state from water
to steam takes place.
Steam generator - embraces the many combinations of heating surfaces, such as
water walls, superheaters, reheaters, economizers, and air heaters.
Steam generating units - consists of a steam generator and its associated
equipment, including fuel burning, ash removal, and draft systems.
,What are the three general methods of calculating the output rating of a boiler?
1) One square meter of heating surface equals 10 kW. Where a computation is to
be made of a curved surface, the surface having the greater radius shall be taken.
2)Where electric power is used as the heat source, the boiler rating shall be the
maximum kilowatt rating of the heating element. The actual output will be
somewhat less.
3) Where neither of the above determinations are applicable, an hourly output of
36 MJ is equivalent to 10 kW. This is the calculation employed in determining the
heat balance of a steam plant.
Steam generators are often rated in terms of
maximum continuous steam output in kg/hr at design temperature and pressure.
The kg/hr rating at the stop valves must include reheater sections of steam
generating units.
Steam generators supplying steam to turbo-alternators are often rated in
megawatts, because the energy supplied to the turbines is converted to electrical
power. This is not an accurate measure of the energy output because the turbine
and generator efficiencies are not considered.
What are the standard conditions for comparing boilers/equivalent evaporation?
,The amount of heat necessary to convert 1 kg of water at 100 ℃ into 1 kg of 100%
dry steam at 101.325 kPa and 100 ℃
What is the factor of evaporation?
The ratio between the heat taken per kg of steam under actual conditions and the
heat taken in evaporating 1 kg of dry steam at 100 ℃
What are the 5 fundamental requirements, or objectives, for boiler design?
- Efficiency
- Reliability
- Cost
- Serviceability
- Safety
When looking at boiler design, which components will be influenced due to the
type of fuel being used?
- The furnace size or heating surface
- The placement of the heating surface
- The equipment needed to prepare and burn the fuel
- The size and type of heat recovery equipment
- The fuel gas treatment devices
, What is the most common type of solid fuel that is burned?
Pulverized coal
For the same output, which furnace must be the largest for gas, oil or coal?
The coal furnaces must be larger, but the velocities of the combustion gases must
be slower. The combustion process is slower, because the solid coal releases
volatile matter which is then oxidized.
What are the differences in furnace size needed for the different types of coal?
High-slagging lignite coal will require a larger furnace volume than volatile
bituminous or subbituminous coal.
Medium-sized furnaces are specified for low-slagging types of lignite coal.
What are the design parameters used for oil-fired furnaces?
- The time needed to completely combust the fuel
- The need to limit furnace wall temperatures
CORRECT ANSWERS| 2026 UPDATED
One boiler horsepower is equal to how many kW
9.809kW
This is still the common measure of capacity for small boilers, where large boiler
capacity is given in the number of kg of steam per hour.
What are the definitions of boiler, steam generator and steam generating unit?
Boiler - strictly speaking are the elements in which the change of state from water
to steam takes place.
Steam generator - embraces the many combinations of heating surfaces, such as
water walls, superheaters, reheaters, economizers, and air heaters.
Steam generating units - consists of a steam generator and its associated
equipment, including fuel burning, ash removal, and draft systems.
,What are the three general methods of calculating the output rating of a boiler?
1) One square meter of heating surface equals 10 kW. Where a computation is to
be made of a curved surface, the surface having the greater radius shall be taken.
2)Where electric power is used as the heat source, the boiler rating shall be the
maximum kilowatt rating of the heating element. The actual output will be
somewhat less.
3) Where neither of the above determinations are applicable, an hourly output of
36 MJ is equivalent to 10 kW. This is the calculation employed in determining the
heat balance of a steam plant.
Steam generators are often rated in terms of
maximum continuous steam output in kg/hr at design temperature and pressure.
The kg/hr rating at the stop valves must include reheater sections of steam
generating units.
Steam generators supplying steam to turbo-alternators are often rated in
megawatts, because the energy supplied to the turbines is converted to electrical
power. This is not an accurate measure of the energy output because the turbine
and generator efficiencies are not considered.
What are the standard conditions for comparing boilers/equivalent evaporation?
,The amount of heat necessary to convert 1 kg of water at 100 ℃ into 1 kg of 100%
dry steam at 101.325 kPa and 100 ℃
What is the factor of evaporation?
The ratio between the heat taken per kg of steam under actual conditions and the
heat taken in evaporating 1 kg of dry steam at 100 ℃
What are the 5 fundamental requirements, or objectives, for boiler design?
- Efficiency
- Reliability
- Cost
- Serviceability
- Safety
When looking at boiler design, which components will be influenced due to the
type of fuel being used?
- The furnace size or heating surface
- The placement of the heating surface
- The equipment needed to prepare and burn the fuel
- The size and type of heat recovery equipment
- The fuel gas treatment devices
, What is the most common type of solid fuel that is burned?
Pulverized coal
For the same output, which furnace must be the largest for gas, oil or coal?
The coal furnaces must be larger, but the velocities of the combustion gases must
be slower. The combustion process is slower, because the solid coal releases
volatile matter which is then oxidized.
What are the differences in furnace size needed for the different types of coal?
High-slagging lignite coal will require a larger furnace volume than volatile
bituminous or subbituminous coal.
Medium-sized furnaces are specified for low-slagging types of lignite coal.
What are the design parameters used for oil-fired furnaces?
- The time needed to completely combust the fuel
- The need to limit furnace wall temperatures
