Stationary Engineering Exam Questions
With All Correct Answers
/ What are drum internals? - Answer-Drums internals comprise all apparatus with in a
drum, including all baffles that quiet or separate the steam and water, the various
devices that may be used for affecting the separation of the steam and water, and the
various chemical and feed water admissions piping and blow down lines
/.What do scrubbers remove? - Answer-They remove the entrained moisture in the
steam. The scrubber is not highly effective in removing small amounts of fine steam
mist, but it suffices to eliminate most of the usual spray and splatter as well as to break
up and eliminate any dry foam
After passing through a washer, the moisture droplets in the steam are enlarged. This
increases the effectiveness of the scrubber and helps reduce the carry-over.
/.Explain how a scrubber works? - Answer-The steam passed between closely fitted
corrugated plates or screens on which the mists are deposited in an action comparable
to filtration. The velocity is low to avoid re-entrainment. The collected water is dripped
by gravity to the boiler water below.
The efficiency of the scrubber depends upon the following variables.
a. Surface area
b. Low steam velocity
c. Steam passage irregularities
d. Time of contact
/.Name different types of water walls - Answer-Bare-Plate Walls- All internally fired,
portable or integral fire box boilers, such as scotch marine or locomotive boilers.
Bare-Tube Wall- They may be constructed of plain tubes, fin tubes or studded tubes,
with a firebrick or refractory backing.
Covered-Tubed Walls- Consist of tubes protected either by integral blocks or attached
blocks. Blocks may be integral blocks of metal or attached blocks of metal, refractory or
metal-enclosed refractory.
The purpose of the protection is to eliminate erosion and corrosion by the combustion
products of waste heat, assist combustion, prevent escape of molten slag and provide a
chill for a moving fuel bed
, /.What types of valves are found on a water wall header? - Answer-Blow-off connections
are provided in each of the lower water wall headers for the removal of sludge. Care
must be taken in making use of these blow downs. To avoid upsetting the circulation of
water in the water wall, the water wall should never be blown down while the boiler is
steaming.
/.What is a forced circulation boiler? - Answer-Forced circulation is what makes
controlled circulation possible. In the C & E design it involves the use of a pump or
pumps to force water through all the steam-generating circuits. Thus insuring a positive
flow in one direction at all times, regardless of the rate of heat application.
/.Describe a box header - Answer-Two flat plates, the tube sheet and the handhole are
flanged over. These are either joined together or joined to a wrapper sheet, by riveting.
The flat surfaces are stayed by hollow steel stay bolts, screwed into each sheet and
then riveted over against the sheet. The tubes are fastened to the tube sheet by being
expanded in the tube holes and then are flared slightly to increase the holding power.
/.What material is used to build a furnace wall? - Answer-Water tubes, firebrick, block-
refractory face, cast iron, steel or ally steel.
Insulating block, expanded metal, insulating cement, plastic and ceramic refractories.
Insulation such as mineral wool and a steel exterior casing.
/.What are the different types of brick used in boiler construction? - Answer-First-quality
firebrick are made of fire clay having an alumina content of about 40% and fusion
temperature of 3000 to 31000.
Second and Third quality firebrick have lower alumina content and lower fusion
temperatures and should ever be used in lining combustion chambers.
Other refractory materials used in firebricks are kaolin, diaspore, cyanite and silicon
carbide.
/.What are steam risers and where are they located? - Answer-In water tube boilers the
convection heating surface is arranged so that some of the tubes act as downcomers
and the balance act as risers depending upon the relative amount of heat to which the
tubes are exposed to direct radiant heat and higher temperatures, act as risers and the
balance as downcomers.
/.What is a riser tube? - Answer-a passage that routes water and steam into a drum
from an upper water wall header.
/.What is the ramp rate of a boiler? - Answer-Ramp rate is the degrees Fahrenheit per
hour rise that metal surface temperatures are exposed to when bringing up a boiler to
rated conditions of temperature and load.
With All Correct Answers
/ What are drum internals? - Answer-Drums internals comprise all apparatus with in a
drum, including all baffles that quiet or separate the steam and water, the various
devices that may be used for affecting the separation of the steam and water, and the
various chemical and feed water admissions piping and blow down lines
/.What do scrubbers remove? - Answer-They remove the entrained moisture in the
steam. The scrubber is not highly effective in removing small amounts of fine steam
mist, but it suffices to eliminate most of the usual spray and splatter as well as to break
up and eliminate any dry foam
After passing through a washer, the moisture droplets in the steam are enlarged. This
increases the effectiveness of the scrubber and helps reduce the carry-over.
/.Explain how a scrubber works? - Answer-The steam passed between closely fitted
corrugated plates or screens on which the mists are deposited in an action comparable
to filtration. The velocity is low to avoid re-entrainment. The collected water is dripped
by gravity to the boiler water below.
The efficiency of the scrubber depends upon the following variables.
a. Surface area
b. Low steam velocity
c. Steam passage irregularities
d. Time of contact
/.Name different types of water walls - Answer-Bare-Plate Walls- All internally fired,
portable or integral fire box boilers, such as scotch marine or locomotive boilers.
Bare-Tube Wall- They may be constructed of plain tubes, fin tubes or studded tubes,
with a firebrick or refractory backing.
Covered-Tubed Walls- Consist of tubes protected either by integral blocks or attached
blocks. Blocks may be integral blocks of metal or attached blocks of metal, refractory or
metal-enclosed refractory.
The purpose of the protection is to eliminate erosion and corrosion by the combustion
products of waste heat, assist combustion, prevent escape of molten slag and provide a
chill for a moving fuel bed
, /.What types of valves are found on a water wall header? - Answer-Blow-off connections
are provided in each of the lower water wall headers for the removal of sludge. Care
must be taken in making use of these blow downs. To avoid upsetting the circulation of
water in the water wall, the water wall should never be blown down while the boiler is
steaming.
/.What is a forced circulation boiler? - Answer-Forced circulation is what makes
controlled circulation possible. In the C & E design it involves the use of a pump or
pumps to force water through all the steam-generating circuits. Thus insuring a positive
flow in one direction at all times, regardless of the rate of heat application.
/.Describe a box header - Answer-Two flat plates, the tube sheet and the handhole are
flanged over. These are either joined together or joined to a wrapper sheet, by riveting.
The flat surfaces are stayed by hollow steel stay bolts, screwed into each sheet and
then riveted over against the sheet. The tubes are fastened to the tube sheet by being
expanded in the tube holes and then are flared slightly to increase the holding power.
/.What material is used to build a furnace wall? - Answer-Water tubes, firebrick, block-
refractory face, cast iron, steel or ally steel.
Insulating block, expanded metal, insulating cement, plastic and ceramic refractories.
Insulation such as mineral wool and a steel exterior casing.
/.What are the different types of brick used in boiler construction? - Answer-First-quality
firebrick are made of fire clay having an alumina content of about 40% and fusion
temperature of 3000 to 31000.
Second and Third quality firebrick have lower alumina content and lower fusion
temperatures and should ever be used in lining combustion chambers.
Other refractory materials used in firebricks are kaolin, diaspore, cyanite and silicon
carbide.
/.What are steam risers and where are they located? - Answer-In water tube boilers the
convection heating surface is arranged so that some of the tubes act as downcomers
and the balance act as risers depending upon the relative amount of heat to which the
tubes are exposed to direct radiant heat and higher temperatures, act as risers and the
balance as downcomers.
/.What is a riser tube? - Answer-a passage that routes water and steam into a drum
from an upper water wall header.
/.What is the ramp rate of a boiler? - Answer-Ramp rate is the degrees Fahrenheit per
hour rise that metal surface temperatures are exposed to when bringing up a boiler to
rated conditions of temperature and load.
