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单选题
Generating tubes in waste heat boilers are finned to （）.
A
reduce gas flow turbulence
B
prevent exhaust gas corrosion
C
increase the rate of combustion
D
increase the rate of heat transfer
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考题
What is the most usual reason for the fresh water-sea water heat exchanger fouling in the sea side?A.lube oil sludge accumulating in itB.dirt and scale etc , formed on the surfacesC.deformation of the tubes and the shell or the platesD.lube oil leakage into sea-water side
考题
The maximum pressure developed by a waste heat boiler is determined by the main engine exhaust ______.A.gas compositionB.gas temperatureC.pressureD.timing
考题
A bypass line provided around a waste heat auxiliary boiler in a diesel engine exhaust system, may be used to avoid boiler ______.A.corrosion at low engine loadsB.erosion at high engine loadsC.overload at high engine loadsD.scaling at all exhaust temperatures
考题
单选题Before shutting off the fuel supply to stop a medium or high–speed diesel engine, why is it necessary to allow the engine to idle for a few minutes?（）A
To prevent internal damage form local overheatingB
To ensure the fuel nozzles are flushed cleanC
To clear the smoke stackD
To let the waste heat boiler reduce its rate of steam generation
考题
单选题Which of the following items is necessary for all waste heat boiler installations, regardless of design or manufacturer? （）A
Control of evaporationB
A separate means to prevent feed-water contaminationC
Power circulating pumpD
Super-heater
考题
单选题Which of the diesel engine cylinder liners listed has internal cooling water passages?（）A
Internally finned linerB
Externally finned linerC
Wet linerD
Integral water-jacket liner
考题
单选题An exhaust gas bypass is installed on a waste heat boiler in order to （）.A
bypass exhaust gas at high loads to prevent excessive back pressureB
bypass a portion of the exhaust gas at peak loads for better efficiencyC
recycle exhaust gas to the turbochargerD
minimize moisture condensation in the boiler gas passages at low loads
考题
单选题The diesel engine exhaust gas bypass, as fitted with some waste heat boilers, is installed to （）A
prevent engine back pressure at heavy loadsB
increase total engine efficiency at low loadsC
prevent boiler corrosion at low engine loadsD
improve engine fuel consumption at any load
考题
单选题If the jacket water temperature of an operating diesel engine suddenly rises above normal, the cause can be attributed to （）.A
an overfilled expansion tankB
excess chromate treatment of the jacket waterC
a clogged raw water sea suctionD
cavitation erosion of the heat exchanger tubes
考题
单选题Waterside scale in a fire-tube boiler may cause （）.A
increased heat transferB
fireside erosionC
high steam demandD
overheated tubes
考题
单选题The rate of heat transfer between the hot and cold fluids passing through a shell-and-tube type heat exchanger will （）.A
remain constant along the tubes lengthB
be greatest in a single pass counter flow heat exchangerC
remain constant throughout the heat exchangerD
vary from section to section through out the heat exchanger
考题
单选题The purpose of designing some waste heat boilers with sinuous fire tubes, is to（）A
increase exhaust gas velocity through the boilerB
reduce accumulations of carbon deposits on the heat transfer surfacesC
eliminate exhaust gas pulsations and noiseD
increase the rate of heat transfer to the waterside
考题
单选题Diesel engine waste heat boiler construction is usually of the fire-tube or（）A
cyclone furnace boiler typeB
dry back boiler typeC
water-tube typeD
critical circulation boiler type
考题
单选题Which of the following statements concerning fire-tube boilers is correct?（）A
Combustion gases flow through the tubesB
Flames impinge on the tubesC
Combustion occurs in the tubesD
Water flows through the tubes
考题
单选题The maximum pressure developed by a waste heat boiler is determined by the main engine exhaust （）.A
gas compositionB
gas temperatureC
pressureD
timing
考题
单选题Exhaust pipes for separate diesel engines can be combined only when （）A
space limitations prevent separately run pipesB
the engines are small auxiliary unitsC
they are arranged to prevent gas backflow to each engineD
a waste heat boiler is installed
考题
单选题Fins are installed on the fireside of water-tubes used in waste boiler to（）A
decrease the velocity of gases flowing past the tubesB
increase the rate of heat transferC
reduce accumulations carbon depositsD
direct the flow of gases
考题
单选题The heat used to change a liquid to a vapor is called （）.A
latent heat of fusionB
latent heat of vaporizationC
specific heat of vaporizationD
latent heat of the gas
考题
单选题In motor ship, （） is often used to recover some of the heat carried in the exhaust gases from the main engine.A
an diesel oil heaterB
a waste heat boilerC
a fresh water generatorD
all the above
考题
单选题Fins are installed on the generating tube surfaces in waste heat boilers to （）.A
prevent soot fires in the exhaust systemB
prevent exhaust gas erosion of the tubesC
increase the velocity of exhaust gas flowD
increase the rate of heat transfer
考题
单选题Which of the following equipment can not be used for the waste heat recovery of the M/E to further improve its thermal efficiency?（）A
M/E turbochargerB
exhaust gas boilerC
incineratorD
fresh water generator
考题
单选题The PRIMARY function of a waste heat boiler is to （）.A
reduce engine exhaust noiseB
reduce engine back pressureC
recover heat which otherwise would be lostD
increase turbocharger efficiency
考题
单选题To avoid impingement attack, care must be taken with the water （） through the tubes of the heat exchangers.A
temperatureB
velocityC
densityD
viscosity
考题
单选题A waste heat boiler is installed on some diesel propelled vessels to （）.A
provide steam for emergency propulsionB
provide steam for the turbo-generatorC
heat the waste water tanksD
steam for warming engines
考题
单选题A SECONDARY function of a waste heat boiler is to （）.A
reduce engine exhaust noiseB
reduce engine back pressureC
increase engine cycle efficiencyD
increase turbocharger efficiency
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