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单选题
On a multistage flash-type evaporator, the flash chamber is （）
A
combined as part of the salt water feed heater
B
the open area above the brine levels in the first and second stages
C
combined as part of the distillate cooler
D
another term used to describe the vapor feed heater
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更多 “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” 相关考题
考题
The condensers located in various stages of a flash evaporator are cooled by( ).A.distillateB.seawaterC.brineD.air
考题
The process during which liquid containing a reasonable amount of sensible heat at a particular pressure immediately changes into steam after admitted to a chamber at a lower pressure is called _____.A.boiling offB.flash evaporationC.condensationD.none of the above
考题
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
考题
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 flash-evaporator is different with the submerged-tube evaporator in that for the former（）A
Water is heated into vapor on heating surfacesB
Water is vaporized by pressure differenceC
There are no heating-transfer surfacesD
There are more heating-transfer surfaces
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A flash-type evaporator discharges heated seawater into a chamber that is maintained at a pressure than the vapor pressure of the entering heated seawater, and subsequently the flashed water vapor thereby produced（）A
lower condensingB
higher coolingC
lower coolingD
higher condensing
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
考题
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
考题
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
考题
单选题The efficiency of a flash type evaporator can be increased by（）A
lowering brine discharge densityB
decreasing the absolute pressure of each stageC
increasing the saltwater feed heater temperatureD
increasing the pressure at the spray pipe
考题
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Early models of the flash-type evaporators used a separate shell-and-tube heat exchanger as the air ejector condenser.More recent models use a combined air ejector condenser with the（）A
distilling condenserB
salt water feed heaterC
distillate coolerD
flash chamber
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
考题
单选题In a flash distilling unit, evaporator feed (seawater) first absorbs heat in the （）.A
vapor feed heaterB
air ejector condenserC
saltwater heaterD
distillate cooler
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