NIULPE STUDY
1. Low-Pressure Steam Boiler <Ans> A boiler that operates at a maximum
allowable working pressure (MAWP) of not more than 15 psi. Primarily used for
heating buildings such as schools, apartments, warehouses, and factories, and for
heating domestic water.
2. High-Pressure Steam Boiler <Ans> A boiler that operates at a maximum
allowable working pressure (MAWP) of more than 15 psi. Also known as power
boilers. Used in generating electricity and in industrial and commercial locations
3. Firetube Steam Boiler <Ans> A boiler in which hot gases of combustion pass
through tubes that are surrounded by water. May be either high pressure or low
pressure. Firetube boilers are used where moderate pressures are needed and
large quan- tities of steam are not required. Common types include <Ans>
Horizontal return tubular boiler, scotch marine boiler, and vertical firetube boiler.
4. Advantages of FIretube Boilers <Ans> Design for pressure up to a maximum
of 350 psi and approximately 2000 BHP. Advantages <Ans> Can be factory
assembled, initial cost is less than a watertube boiler, requires little or no setting,
contains larger volume of water for a given size compared to a watertube boiler,
requires less headroom.
5. Steam Pressure and Temperature Relationship <Ans> 20-259, 30-274, 40-
287,
50-298, 60-307, 70-316, 80-324, 90-331, 100-338, 150-366, 200-388, 250-406,
300-422 (PSI-DEGREES)
6. Heating Surface <Ans> A part of a boiler with water on one side and heat and
gases of combustion on the other. By increasing the heating surface, more heat is
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, transferred from the gases of combustion.
7. Thermal Efficiency <Ans> When larger quantities of steam are generated, the
thermal efficiency of a boiler increases. Thermal efficiency is the ratio of the heat
absorbed by a boiler (output) to the heat available in the fuel (input) including
radiation and convection losses. Modern firetube boilers with improved design and
teat transfer rates have achieved thermal efficiency rates as high as 90% to 95%
8. Furnaces <Ans> A furnace is a location where the combustion process
takes place. A furnace is also known as a firebox or combustion chamber.
Placing an internal furnace within the boiler shell greatly increases the heating
surface. This also increases heat absorption through radiant heat transfer.
9. Dry-Back Boiler <Ans> A firetube boiler with a refractory-lined rear door that
directs the gases of combustion from the furnace to the first pass of tubes or from
one section of tubes to another.
10. Wet-Back Boiler <Ans> A firetube boiler with three tube sheets and a water-
cooled turnaround chamber, with a water leg formed between the rear tube sheet
and the chamber. This water le directs the gases of combustion from the furnace t o
the first pass of the tubes and then through succeeding passes.
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15
1. Low-Pressure Steam Boiler <Ans> A boiler that operates at a maximum
allowable working pressure (MAWP) of not more than 15 psi. Primarily used for
heating buildings such as schools, apartments, warehouses, and factories, and for
heating domestic water.
2. High-Pressure Steam Boiler <Ans> A boiler that operates at a maximum
allowable working pressure (MAWP) of more than 15 psi. Also known as power
boilers. Used in generating electricity and in industrial and commercial locations
3. Firetube Steam Boiler <Ans> A boiler in which hot gases of combustion pass
through tubes that are surrounded by water. May be either high pressure or low
pressure. Firetube boilers are used where moderate pressures are needed and
large quan- tities of steam are not required. Common types include <Ans>
Horizontal return tubular boiler, scotch marine boiler, and vertical firetube boiler.
4. Advantages of FIretube Boilers <Ans> Design for pressure up to a maximum
of 350 psi and approximately 2000 BHP. Advantages <Ans> Can be factory
assembled, initial cost is less than a watertube boiler, requires little or no setting,
contains larger volume of water for a given size compared to a watertube boiler,
requires less headroom.
5. Steam Pressure and Temperature Relationship <Ans> 20-259, 30-274, 40-
287,
50-298, 60-307, 70-316, 80-324, 90-331, 100-338, 150-366, 200-388, 250-406,
300-422 (PSI-DEGREES)
6. Heating Surface <Ans> A part of a boiler with water on one side and heat and
gases of combustion on the other. By increasing the heating surface, more heat is
1/
15
, transferred from the gases of combustion.
7. Thermal Efficiency <Ans> When larger quantities of steam are generated, the
thermal efficiency of a boiler increases. Thermal efficiency is the ratio of the heat
absorbed by a boiler (output) to the heat available in the fuel (input) including
radiation and convection losses. Modern firetube boilers with improved design and
teat transfer rates have achieved thermal efficiency rates as high as 90% to 95%
8. Furnaces <Ans> A furnace is a location where the combustion process
takes place. A furnace is also known as a firebox or combustion chamber.
Placing an internal furnace within the boiler shell greatly increases the heating
surface. This also increases heat absorption through radiant heat transfer.
9. Dry-Back Boiler <Ans> A firetube boiler with a refractory-lined rear door that
directs the gases of combustion from the furnace to the first pass of tubes or from
one section of tubes to another.
10. Wet-Back Boiler <Ans> A firetube boiler with three tube sheets and a water-
cooled turnaround chamber, with a water leg formed between the rear tube sheet
and the chamber. This water le directs the gases of combustion from the furnace t o
the first pass of the tubes and then through succeeding passes.
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15
