০০। A refractory wall separating the stock and the source of heat is provided in a
ক) updraft kiln
খ) muffle furnace
গ) continuous furnace
ঘ) none of these
০১। Acid dew point temperature (ADT) of a flue gas produced by the combustion of a fuel containing 1% sulphur may be about __________ °C.
ক) 80
খ) 130
গ) 180
ঘ) 250
০২। Advantages of use of preheated combustion air are
ক) saving in fuel consumption.
খ) reduction in scale losses.
গ) increase in flame temperature.
ঘ) all (a), (b) and (c).
০৩। Air filtration in a furnace
ক) reduces its thermal efficiency.
খ) is indicated by flame sting out.
গ) increases the flue gas temperature.
ঘ) none of these.
০৪। Amount of coal lost in ash particle, which is carried through the boiler system, depends upon the
ক) physical nature, ash content and fineness of the coal.
খ) amount of excess air supplied and load on the boiler.
গ) type of burner and combustion chamber.
ঘ) all (a), (b) and (c)
০৫। An electric furnace producing heat by means of an electric arc struck between each of three electrodes and the charge is called __________ furnace.
ক) resistance
খ) arc
গ) low frequency induction
ঘ) none of these
০৬। An example of a periodic furnace is the
ক) blast furnace stoves
খ) blast furnace
গ) coke oven heating chamber
ঘ) rotary kilns
০৭। An example of indirectly heated furnace is the
ক) soaking pit
খ) muffle furnace
গ) reheating furnace
ঘ) none of these
০৮। An example of recuperative furnace is the
ক) soaking pit
খ) open hearth furnace
গ) coke ovens
ঘ) none of these
০৯। An example of shaft furnace is the
ক) L.D. converter
খ) glass melting tank
গ) blast furnace
ঘ) soaking pit
১০। An improved and fuel efficient version of the pusher type reheating furnace is the __________ furnace.
ক) walking beam
খ) shaft
গ) tunnel
ঘ) rotary hearth
১১। Artificial draught produced by a fan in the furnace can be controlled by the
ক) speed of the fan.
খ) damper.
গ) variation in the pitch of fan blades.
ঘ) all (a), (b) and (c).
১২। Blast furnace stoves are meant for heating
ক) air
খ) blast furnace gas
গ) steam
ঘ) none of these
১৩। Calcination of limestone to produce lime is done in a __________ kiln.
ক) tunnel
খ) rotary
গ) vertical shaft
ঘ) both (b) and (c)
১৪। Cement Kiln is a
ক) rotary Kiln
খ) tunnel Kiln
গ) natural draft furnace
ঘ) batch furnace
১৫। Ceramic coating material for furnace refractory, which increases its emissivity and thus the radiation heat transfer rate in the furnace, comprises of
ক) graphite powder
খ) thoria
গ) zircon powder
ঘ) beryllium
১৬। Ceramic recuperators (made of SiC) is economical, only when used for preheating combustion air above __________ °C.
ক) 250
খ) 650
গ) 850
ঘ) 1000
১৭। Ceramic recuperators compared to metallic recuperators for the same duty
ক) are lighter.
খ) occupy more space.
গ) are less costly.
ঘ) have higher pressure differential between flue gas & air side.
১৮। Circulation of gases in furnace is caused by the
ক) change in volume during a change of temperature.
খ) difference in density between hot and cold gases.
গ) furnace pressure in conjunction with draft in flues.