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单选题
In a flash distilling unit, evaporator feed (seawater) first absorbs heat in the （）.
A
vapor feed heater
B
air ejector condenser
C
saltwater heater
D
distillate cooler
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更多 “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” 相关考题
考题
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
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One advantage of a flash distilling plant when compared to a submerged tube distiller is（）A
greater distillate purity through high temperature evaporationB
cold shocking for scale removal is not requiredC
less internal corrosion because of lower brine densityD
less feed-water is required for equal plant capacity
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
考题
单选题Tube leaks in the distillate cooler of a two stage flash evaporator will result in （）.A
loss of second stage vacuumB
contamination of the distillateC
lower feed inlet temperatureD
contamination of the second stage condenser
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Why will a two stage flash type distilling plant tend to operate more efficiently when operating in cold seawater?（）A
The colder seawater passing through the condenser tube bundles of the various stages increases evaporator vacuumB
The amount of heated feed water discharged from the feed water heater after cndenser is increasedC
Fewer non-condensable gases are created by the flow of colder seawaterD
More seawater is allowed to pass through the flint stage overflow weir
考题
单选题The second stage feed-water temperature and shell absolute pressure in a multistage, flash type, distilling plant is （）A
higher than the first stage feed-water temperature and absolute shell pressureB
lower than the first stage feed-water temperature and absolute shell pressureC
the same as the first stage feed-water temperature and absolute shell pressureD
not related to the feed-water temperature and absolute shell pressure
考题
单选题With a vacuum boiling evaporator, the remainder of sea water fed to the evaporator is pumped out by （）.A
a brine pumpB
an air ejectorC
a feed pumpD
distillate pump
考题
单选题In a flash evaporator, scale as a result of higher than normal temperatures in most likely to occur in the （）A
second stage feed heaterB
saltwater feed heaterC
distillate coolerD
second stage vapor separator
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In which of the areas listed would you expect to find the highest salt concentration in a flash evaporator?（）A
Distiller air ejector cooling mediumB
Saltwater heater dischargeC
First-stage internal feed boxD
Second-stage internal feed box
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A vacuum is initially created in a flash type distilling plant by（）.A
the flashing of the feed waterB
the condensation of the saltwater feedC
air ejectors, eductors, or a separate vacuum pumpD
condensation of the distillate
考题
单选题When securing a flash-type evaporator for an extended period of time, you should （）.A
fill the unit with saltwaterB
fill the unit with de-scaling compoundC
completely drain the unitD
tightly seal the unit to exclude air
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