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单选题
The efficiency of a flash type evaporator can be increased by（）
A
lowering brine discharge density
B
decreasing the absolute pressure of each stage
C
increasing the saltwater feed heater temperature
D
increasing the pressure at the spray pipe
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考题
The condensers located in various stages of a flash evaporator are cooled by( ).A.distillateB.seawaterC.brineD.air
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A thermostatic expansion valve is properly controlling evaporator superheat. Adjusting this valve to lower the superheat will result in a/anA.evaporator pressure decreaseB.evaporator coil over-feedC.evaporator capacity increaseD.expansion valve diaphragm rupture
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In a flash type evaporator, all saltwater heaters are vented through individual vent cocks to the ______.A.saltwater heater shellB.second-stage condenserC.atmosphereD.second-stage flash chamber
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Which of the listed problems could produce a high absolute pressure within a flash type evaporator?A.production of high salinity distillateB.seawater feed temperature below 165℃C.a leak in the first stage demisterD.a cracked distillate pump vent line
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单选题When a flash-type evaporator is to be secured for an extended period of time, the entire unit should be drained, cleaned, and （）.A
completely filled with saltwaterB
filled with de-scaling compoundC
tightly closed to exclude airD
vented to the atmosphere
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The heated feed-water entering any flash chamber of a flash-type evaporator will（）A
vaporize, with the un-flashed water remaining at the temperature at which it entered the flash chamberB
vaporize, with the un-flashed eater equalizing to the saturation conditions existing in the f lash chamberC
vaporize, with the remaining water a t a temperature greater than it entered the flash chamberD
boil, allowing steam bubbles to rise through the brine at the bottom of the flash chamber
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单选题In a flash type evaporator, all saltwater headers are vented through individual vent cocks to the（）.A
saltwater heater shellB
second-stage condenserC
atmosphereD
second-stage flash chamber
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单选题Fuel oil contamination of an auxiliary diesel engine lube oil can result in（）A
an increased flash pointB
higher lube oil pressuresC
an increased viscosityD
lower lube oil pressures
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单选题For a flash type evaporator, the seawater heater will have to maintain a enough temperature to minimize scale formation（）A
lowerB
higherC
lowD
high
考题
单选题Small droplets of water entrained in the flashed vapor produced in a flash-type evaporator, are removed by the （）A
spray pipesB
demistersC
condensersD
splash baffles
考题
单选题In the operation of a flash type evaporator equipped with air ejectors,the air and non- condensable gases are evacuated directly from the （）.A
first stage flash chamberB
second stage flash chamberC
first stage after condenserD
second stage distilling condenser
考题
单选题The demisters installed in a flash-type evaporator serve to （）A
deaerate the first effect distillateB
filter the condensed flash vaporsC
deaerate the first and second effect distillateD
remove small water droplets entrained in the flashed vapor
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单选题If the compression ratio is increased on any diesel engine, （）A
the expansion ratio will decreaseB
combustion will be slowed downC
thermal efficiency will decreaseD
thermal efficiency will increase
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单选题One distinct advantage of flash type evaporators, as compared to most other evaporators, is that in a flash evaporator （）.A
high temperature distillate can be re- circulated to induce additional flashingB
scale formation is not a severe problemC
cold shocking is more effective in removing scaleD
water purity is greatly increased at high capacity
考题
单选题The design of for a flash type evaporator is of critical importance because it must provide an optimum feedwater spray pattern that facilitates the flashing process, and it must also maintain a pressure differential between successive stages（）A
condenserB
flashing deviceC
lashing deviceD
vacuum pump
考题
单选题The heated feedwater entering any flash chamber of a flash-type evaporator will（）A
vaporize, with the unflashed water remaining at the temperature at which it entered the flash chamberB
vaporize, with the unflashed water equalizing to the saturation conditions existing in the flash chamberC
vaporize, with the remaining water at the temperature greater than it entered the flash chamberD
boil, allowing steam bubbles to rise through the brine at the bottom of the flash chamber
考题
单选题For a flash type evaporator, a demister is located the condenser（）A
AfterB
beforeC
insideD
outside
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The advantages of flash type evaporators, as compared to submerged tube type evaporators, include （）.A
less internal corrosion because of lower brine densityB
higher temperature evaporation for lower salinity of the distillate producedC
less scale formation in a flash evaporatorD
less feed-water required for a flash evaporator
考题
单选题On a multistage flash-type evaporator, the flash chamber is （）A
combined as part of the salt water feed heaterB
the open area above the brine levels in the first and second stagesC
combined as part of the distillate coolerD
another term used to describe the vapor feed heater
考题
单选题The condensers located in various stages of a flash evaporator are cooled by（）A
distillateB
seawaterC
brineD
air
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On which of the following heated surfaces of a flash type evaporator would you be more likely to find soft scale formation?（）A
Feed-water heater internal tube surfacesB
Internal distillate cooler tubesC
Flash chamber vertical surfacesD
Distilling condenser tubes
考题
单选题Under normal operating conditions, the highest temperature and pressure conditions existing in a flash-type evaporator will occur in the （）.A
first stageB
second stageC
distillate coolerD
salt water feed heater
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