boiler types
Advanced Gas-Cooled Reactor (AGR) - correct answer-still uses graphite as the moderator
and, as in the later Magnox designs, the steam generators and gas circulators are placed
within a combined concrete pressure-vessel/radiation-shield
Basic Gas-Cooled Reactor (Magnox) - correct answer-Gas Cooled, Graphite Moderated Of
the six main commercial reactor types, two (Magnox and AGR) owe much to the very
earliest reactor designs in that they are graphite moderated and gas cooled. Magnox
reactors were built in the UK from 1956 to 1971 but have now been superceded. The
Magnox reactor is named after the magnesium alloy used to encase the fuel, which is
natural uranium metal. Fuel elements consisting of fuel rods encased in Magnox cans are
loaded into vertical channels in acore constructed of graphite blocks.
Boiling Water Reactor (BWR) - - correct answer-In the boiling water reactor (BWR), water
that passes over the reactor core acts as a coolant and the steam source for the turbine.
Chemical Recovery - correct answer-Boilers in Pulp Mills utilizing a mixture of cooking
chemicals and dissolved wood material remaining after sulphate cooking
Dry-Bottom - correct answer-Solid fuel watertube boilers where the bottom ash drops to
bottom ash hoppers.
Fluidized Bed - correct answer-Designed to mix fuel in a upwardly flowing gas stream
allowing for high heat transfer and low combustion temperatures. Technology reduces SO2
and NOx emissions allowing the use of high sulfur coals without adding additional sulfur
removal equipment
Heat Recovery/Waste Heat Steam Generator - correct answer-Heat Recovery Steam
Generators (HRSG) transfer energy from the exhaust of a gas turbine to an unfired or
supplementary fired heat-recovery steam generator to produce steam. Exhaust gases leave
the gas turbine at temperatures of 1000°F (538°C) or higher and can represent more than 75
percent of the total fuel energy input. This energy can be recovered by passing the gases
through a heat exchanger (steam generator) to produce hot water or steam for process
needs. If the amount of steam needed by the process exceeds the amount produced by
simple heat recovery, then supplementary fuel can be burned in the ducting between the gas
turbine and the HRSG. Waste Heat Recovery Boiler (WHRB). These boilers may be either
firetube or watertube design and use heat that would otherwise be discarded to generate
steam. Typical sources of heat for WHRBs include exhaust gases or high temperature
products from an external manufacturing process in refineries and chemical manufacturing
facilities or combustion of a waste fuel in the boiler furnace.
Incinerator/Mass Burn Boiler - correct answer-- Municipal solid waste is burned in a
controlled system after sorting or processing. Mass burn technologies represent over 75% of
all the MSW-to-energy facilities constructed in the United States to date. The major
components of a mass burn facility include refuse receiving and handling, combustion and
Advanced Gas-Cooled Reactor (AGR) - correct answer-still uses graphite as the moderator
and, as in the later Magnox designs, the steam generators and gas circulators are placed
within a combined concrete pressure-vessel/radiation-shield
Basic Gas-Cooled Reactor (Magnox) - correct answer-Gas Cooled, Graphite Moderated Of
the six main commercial reactor types, two (Magnox and AGR) owe much to the very
earliest reactor designs in that they are graphite moderated and gas cooled. Magnox
reactors were built in the UK from 1956 to 1971 but have now been superceded. The
Magnox reactor is named after the magnesium alloy used to encase the fuel, which is
natural uranium metal. Fuel elements consisting of fuel rods encased in Magnox cans are
loaded into vertical channels in acore constructed of graphite blocks.
Boiling Water Reactor (BWR) - - correct answer-In the boiling water reactor (BWR), water
that passes over the reactor core acts as a coolant and the steam source for the turbine.
Chemical Recovery - correct answer-Boilers in Pulp Mills utilizing a mixture of cooking
chemicals and dissolved wood material remaining after sulphate cooking
Dry-Bottom - correct answer-Solid fuel watertube boilers where the bottom ash drops to
bottom ash hoppers.
Fluidized Bed - correct answer-Designed to mix fuel in a upwardly flowing gas stream
allowing for high heat transfer and low combustion temperatures. Technology reduces SO2
and NOx emissions allowing the use of high sulfur coals without adding additional sulfur
removal equipment
Heat Recovery/Waste Heat Steam Generator - correct answer-Heat Recovery Steam
Generators (HRSG) transfer energy from the exhaust of a gas turbine to an unfired or
supplementary fired heat-recovery steam generator to produce steam. Exhaust gases leave
the gas turbine at temperatures of 1000°F (538°C) or higher and can represent more than 75
percent of the total fuel energy input. This energy can be recovered by passing the gases
through a heat exchanger (steam generator) to produce hot water or steam for process
needs. If the amount of steam needed by the process exceeds the amount produced by
simple heat recovery, then supplementary fuel can be burned in the ducting between the gas
turbine and the HRSG. Waste Heat Recovery Boiler (WHRB). These boilers may be either
firetube or watertube design and use heat that would otherwise be discarded to generate
steam. Typical sources of heat for WHRBs include exhaust gases or high temperature
products from an external manufacturing process in refineries and chemical manufacturing
facilities or combustion of a waste fuel in the boiler furnace.
Incinerator/Mass Burn Boiler - correct answer-- Municipal solid waste is burned in a
controlled system after sorting or processing. Mass burn technologies represent over 75% of
all the MSW-to-energy facilities constructed in the United States to date. The major
components of a mass burn facility include refuse receiving and handling, combustion and
