4th Class ABSA Exam Part A Practice Actual Exam
Newest Actual Exam With Complete 1000 Questions
And Correct Detailed Answers (Verified Answers)
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Fluidized Beds - answer-:;Fluidized beds burn intermediate sized particles of fuel at a lower
temperature, in a floating mass of coal and limestone.
Cyclone Furnaces - answer-:;Burn coal in a special, highly turbulent, high temperature combustion
chamber adjacent to the main furnace.
Tramp Metal - answer-:;Ferrous metal contaminants entrained within a solid fuel
Bunkers - answer-:;A large steel container used to store fuel.
Municipal Refuse - answer-:;Comes from:
Freight companies
Storage warehousing and distribution centres
Furnace, home wear, pallets
Demolito construction waste
Household waste recycling
,Mass Burning - answer-:;The act of burning municipal solid waste in a single combustion chamber. Burn
it the way it came, and only remove large non-combustible or bulky items
Refuse-Derived Fuel (RDF) - answer-:;Refuse is separated, classified and sorted to remove recyclable
products, before it is burned in the boiler.
Overfeed Stoker - answer-:;Overfeed stokers add fuel to above the burning bed.
- Spreader stoker is a stoker that uses a rotating wheel that throws fuel onto the bed.
- Air Jet Overfeed stoker: Jets of combustion air are used to propel the fuel through the furnace to the
grate.
- Also called vibrating grate stoker because the grate vibrates and moves the fuel through the furnace.
- Crossed Stoker: Endless moving belt that extends into the furnace from the boiler front. Different from
spreader stoke because the fuel is gravity fed.
Underfeed Stoker - answer-:;Introduce fuel from below the bed.
Retort - answer-:;The channel in an underfeed stoke, extending within the furnace, through which fuel is
forced upward into the fuel bed.
Tuyeres - answer-:;Forms of grates, located adjacent to a retort, through which air is introduced.
Pulverized fuel - answer-:;Allows for low grade materials to be burned more satisfactorily. Also burned
with little excess air.
fluidized bed combustion (FBC) - answer-:;A process where a fuel is burned in a bed of granular particles
that are maintained in mobile suspension by the flow of air and combustion products.
Bubbling Fluidized Bed - answer-:;Air nozzles on base, fuel is given from a tube that comes from the top
or side.
,Region between the top of furnace and the bed is called? - answer-:;Freeboard
Atmospheric and pressurized fluidized bed combustion - answer-:;Atmospheric - more common
Pressurized - less common
Advantages of pressurized:
- Larger power output and 5% more efficient
Disadvantage:
- Complexity
- erosion, corrosion and fouling of gas turbine blades
- low furnace temperatures, which limits steam temp.
- Difficulty feeding fuel and bed materials into pressurized system
Circulating fluidized bed - answer-:;Where gases are at higher velocity sufficient to suspend the particle
bed, due to a larger kinetic energy of the fluid.
Entrained particles are recirculated via an external loop back into the reactor bed.
Advantages and Disadvantages of FBC - answer-:;Advantages:
- Flexibility of fuel
- Smaller plant size
- less fuel preparation
- fuel feed is simple
- high combustion efficiency in coal-fired units
, - improved regulatory compliance in coal-fired units
Disadvantages:
- high power requirements for combustion air
- Carryover (gradual loss of the fluidized bed)
- Poor combustion control at low operating rates
- additional cost to transport limestone
Mercaptan - answer-:;Added to gas to make it smell awful, which can be smelled when leaking.
Gaseous fuels easier to handle than solid fuels because - answer-:;Natural gas requires no on-site
storage.
Biogas vs natural gas - answer-:;Biogas - lack of widespread availability, need storage during times
production exceeds consumption. However, reduced greenhouse emissions & odour control.
Natural Gas- Colourless, odourless unless added. However very clean and no handling equipment
required.
Premix burner - answer-:;Mixes fuel and air in the pipe before it leaves the nozzles. Also called
atmospheric burner because furnace pressure is at or near atmosphere pressure.
After Mix burner - answer-:;Mixing of fuel and air occurs as fuel enters the combustion chamber.
Multi-spud burner - answer-:;Gas in this burner is supplied to a circular manifold, which has several gas
spuds branching off.
Ring Burner - answer-:;Suitable for use in large boilers.
Newest Actual Exam With Complete 1000 Questions
And Correct Detailed Answers (Verified Answers)
|Already Graded A+
Fluidized Beds - answer-:;Fluidized beds burn intermediate sized particles of fuel at a lower
temperature, in a floating mass of coal and limestone.
Cyclone Furnaces - answer-:;Burn coal in a special, highly turbulent, high temperature combustion
chamber adjacent to the main furnace.
Tramp Metal - answer-:;Ferrous metal contaminants entrained within a solid fuel
Bunkers - answer-:;A large steel container used to store fuel.
Municipal Refuse - answer-:;Comes from:
Freight companies
Storage warehousing and distribution centres
Furnace, home wear, pallets
Demolito construction waste
Household waste recycling
,Mass Burning - answer-:;The act of burning municipal solid waste in a single combustion chamber. Burn
it the way it came, and only remove large non-combustible or bulky items
Refuse-Derived Fuel (RDF) - answer-:;Refuse is separated, classified and sorted to remove recyclable
products, before it is burned in the boiler.
Overfeed Stoker - answer-:;Overfeed stokers add fuel to above the burning bed.
- Spreader stoker is a stoker that uses a rotating wheel that throws fuel onto the bed.
- Air Jet Overfeed stoker: Jets of combustion air are used to propel the fuel through the furnace to the
grate.
- Also called vibrating grate stoker because the grate vibrates and moves the fuel through the furnace.
- Crossed Stoker: Endless moving belt that extends into the furnace from the boiler front. Different from
spreader stoke because the fuel is gravity fed.
Underfeed Stoker - answer-:;Introduce fuel from below the bed.
Retort - answer-:;The channel in an underfeed stoke, extending within the furnace, through which fuel is
forced upward into the fuel bed.
Tuyeres - answer-:;Forms of grates, located adjacent to a retort, through which air is introduced.
Pulverized fuel - answer-:;Allows for low grade materials to be burned more satisfactorily. Also burned
with little excess air.
fluidized bed combustion (FBC) - answer-:;A process where a fuel is burned in a bed of granular particles
that are maintained in mobile suspension by the flow of air and combustion products.
Bubbling Fluidized Bed - answer-:;Air nozzles on base, fuel is given from a tube that comes from the top
or side.
,Region between the top of furnace and the bed is called? - answer-:;Freeboard
Atmospheric and pressurized fluidized bed combustion - answer-:;Atmospheric - more common
Pressurized - less common
Advantages of pressurized:
- Larger power output and 5% more efficient
Disadvantage:
- Complexity
- erosion, corrosion and fouling of gas turbine blades
- low furnace temperatures, which limits steam temp.
- Difficulty feeding fuel and bed materials into pressurized system
Circulating fluidized bed - answer-:;Where gases are at higher velocity sufficient to suspend the particle
bed, due to a larger kinetic energy of the fluid.
Entrained particles are recirculated via an external loop back into the reactor bed.
Advantages and Disadvantages of FBC - answer-:;Advantages:
- Flexibility of fuel
- Smaller plant size
- less fuel preparation
- fuel feed is simple
- high combustion efficiency in coal-fired units
, - improved regulatory compliance in coal-fired units
Disadvantages:
- high power requirements for combustion air
- Carryover (gradual loss of the fluidized bed)
- Poor combustion control at low operating rates
- additional cost to transport limestone
Mercaptan - answer-:;Added to gas to make it smell awful, which can be smelled when leaking.
Gaseous fuels easier to handle than solid fuels because - answer-:;Natural gas requires no on-site
storage.
Biogas vs natural gas - answer-:;Biogas - lack of widespread availability, need storage during times
production exceeds consumption. However, reduced greenhouse emissions & odour control.
Natural Gas- Colourless, odourless unless added. However very clean and no handling equipment
required.
Premix burner - answer-:;Mixes fuel and air in the pipe before it leaves the nozzles. Also called
atmospheric burner because furnace pressure is at or near atmosphere pressure.
After Mix burner - answer-:;Mixing of fuel and air occurs as fuel enters the combustion chamber.
Multi-spud burner - answer-:;Gas in this burner is supplied to a circular manifold, which has several gas
spuds branching off.
Ring Burner - answer-:;Suitable for use in large boilers.
