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单选题
With a vacuum boiling evaporator, the remainder of sea water fed to the evaporator is pumped out by （）.
A
a brine pump
B
an air ejector
C
a feed pump
D
distillate pump
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考题
单选题Excessive scale formation in a distilling plant may result from （）.A
poor distillate qualityB
reduced evaporator capacityC
low brine concentrationD
improper vacuum regulation
考题
单选题The vacuum maintained in the salt water feed heater shell of a flash-type evaporator is generally accomplished by （）.A
a separate air ejector unitB
a direct unimpeded connection between second stage and salt water feed heaterC
either by vacuum drag or an external line from the first stage via a fixed orificeD
the fixed orifice provided in the steam supply line
考题
单选题Because of the reduced （） in the distillation system, some of the sea water boils as it flows through the tubes of the evaporator.A
pressureB
temperatureC
densityD
volume
考题
单选题We use （） to distill fresh water from sea water.A
engineB
sea water pumpC
cylinder coolerD
fresh water generator
考题
单选题When distilling sea water the cooling water discharging from the distiller is fed back to evaporator as feed water （）.A
to decrease scale formationB
for better cooling effectC
for more economical purposeD
to raise vacuum
考题
单选题The fresh water generator produces fresh water （）.A
by cooling sea waterB
by heating sea waterC
by evaporation of sea waterD
by purifying sea water
考题
单选题What is the operating principal of a flash type evaporator?（）A
Sea water is heated to boiling temperature under a vacuumB
Sea water is passed over heated plates in a thin filmC
Heated sea water is injected into a vacuum chamberD
Sea water is forced through a heated eductor
考题
单选题What should you apply to a fathometer reading to determine the depth of water?（）A
Subtract the draft of the vesselB
Add the draft of the vesselC
Subtract the sea water correctionD
Add the sea water correction
考题
单选题Less scale formation occurs in a flash evaporator than in a submerged tube evaporator because （）.A
the distillate produced has greater purityB
no boiling occurs on heat transfer surfacesC
evaporation occurs at a higher rateD
the incoming feed is at a higher temperature
考题
单选题When distilling salt water the cooling water discharging from the distiller is fed back to evaporator as feed water （）.A
to cut down the amount of cooling water neededB
to prevent an excess amount of cooling water from being discharged to the bilgesC
to supply hot water to the evaporator for more economical operationD
None of the above is tree
考题
单选题In a flash type evaporator, the brine overboard pump is vented directly to the（）A
saltwater heater shellB
the condensation of the saltwater feedC
air ejectors, eductors, or a separate vacuum pumpD
condensation of the distillate
考题
单选题In （）, hot diesel engine jacket water passes over the stack and heats the sea water passing through the tubes.A
a flash generatorB
a flash evaporatorC
a vacuum boiling evaporatorD
a boiler
考题
单选题In a diesel engine jacket water cooler, with seawater cooling the fresh water, the（）A
sea water temperature must never be warmer than 40℃B
jacket water pressure should always be greater than the sea water pressureC
jacket water temperature must always be less than 60℃D
jacket water pressure must always be less than the sea water pressure
考题
单选题Because of the reduced （） in the vacuum boiling evaporator, some of the sea water boils as it flows through the tubes.A
temperatureB
water levelC
pressureD
rate of flow
考题
单选题Which of the following descriptions best identifies the operating principal of a flash-type evaporator?（）A
Sea water is heated to boiling temperature while under a vacuumB
Sea water is passed over heated plates in a thin filmC
Heated sea water is injected into a vacuum chamberD
Sea water is forced through a heated eductor
考题
单选题Which of the listed conditions will cause the feed water that has not flashed to vapor in the first-stage of a flash evaporator, to flow into the second-stage?（）A
Gravity siphon effectB
Higher vacuum in the second-stageC
Difference in brine density between first and second stagesD
lower pressure in first-stage
考题
单选题More than one stage of evaporation can take place by admitting the sea water into chambers with progressively （） pressure in the flash evaporator.A
lowerB
higherC
the lowerD
the higher
考题
单选题Which one of the followings might not be employed to create vacuum for flash type evaporator? （）A
high-pressure steam-driven air-ejectorB
motor-driven vacuum pumpC
water-motivated air eductorD
centrifuge pump
考题
单选题In a vacuum boiling evaporator, the fresh water generated is pumped out by （）.A
a brine pumpB
an air ejectorC
a feed water pumpD
a condensate pump
考题
单选题When a vacuum boiling evaporator works, the hot jacket water will pass over the tube stack and （） the sea water passing through the tubes.A
disposeB
dissolveC
heatD
dissipates
考题
单选题A vacuum is initially established in the first and second stages of a low pressure evaporator by the use of （）A
vacuum drag from the auxiliary condensate systemB
individual vacuum pumpsC
a single non-condensing air ejectorD
a two stage air ejector
考题
单选题Which of the following statements is correct relative to distillation plant operation?（）A
Distillation is the process of boiling seawater to produce vapor which is condensed into fresh waterB
Evaporation is the second part of the distillation process where brine is removedC
Brine is the result of condensed sea water vaporD
Distillate is the product resulting from the evaporation of fresh water vapor
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