更多"In a flash evaporator, scale as a r"的相关试题:
[单项选择]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
[单项选择]Less scale formation occurs in a flash evaporator than in a submerged tube evaporator because （）.
A. the distillate produced has greater purity
B. no boiling occurs on heat transfer surfaces
C. evaporation occurs at a higher rate
D. the incoming feed is at a higher temperature
[单项选择]Scale accumulation on evaporator heat exchange surfaces （）.
A. increases brine density
B. increases distillate salinity
C. reduces metal corrosion
D. reduces heat transfer
[单项选择]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 condensing
B. higher cooling
C. lower cooling
D. higher condensing
[单项选择]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 chamber
B. second stage flash chamber
C. first stage after condenser
D. second stage distilling condenser
[单项选择]In a flash type evaporator, all saltwater headers are vented through individual vent cocks to the（）.
A. saltwater heater shell
B. second-stage condenser
C. atmosphere
D. second-stage flash chamber
[单项选择]The flash-evaporator is different with the submerged-tube evaporator in that for the former（）
A. Water is heated into vapor on heating surfaces
B. Water is vaporized by pressure difference
C. There are no heating-transfer surfaces
D. There are more heating-transfer surfaces
[单项选择]The demisters installed in a flash-type evaporator serve to （）
A. deaerate the first effect distillate
B. filter the condensed flash vapors
C. deaerate the first and second effect distillate
D. remove small water droplets entrained in the flashed vapor
[单项选择]In a flash type evaporator, the brine overboard pump is vented directly to the（）
A. saltwater heater shell
B. the condensation of the saltwater feed
C. air ejectors, eductors, or a separate vacuum pump
D. condensation of the distillate
[单项选择]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
[单项选择]For a flash type evaporator, a demister is located the condenser（）
A. After
B. before
C. inside
D. outside
[单项选择]For a flash type evaporator, the seawater heater will have to maintain a enough temperature to minimize scale formation（）
A. lower
B. higher
C. low
D. high
[单项选择]When securing a flash-type evaporator for an extended period of time, you should （）.
A. fill the unit with saltwater
B. fill the unit with de-scaling compound
C. completely drain the unit
D. tightly seal the unit to exclude air
[单项选择]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
[单项选择]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. condenser
B. flashing device
C. lashing device
D. vacuum pump
[单项选择]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 saltwater
B. filled with de-scaling compound
C. tightly closed to exclude air
D. vented to the atmosphere
[单项选择]Constant superheat is maintained at the evaporator outlet of a refrigeration coil by a（）
A. solenoid valve
B. low pressure cutout switch
C. king valve
D. thermal expansion valve
[单项选择]The refrigerant leaves the evaporator of a refrigeration system as a low pressure （）.
A. sub-cooled liquid
B. high temperature liquid
C. oil saturated liquid
D. superheated vapor
[单项选择]Distilled water from an evaporator may be discharged into a potable water tank （）.
A. through a detachable hose connection
B. after passing through an activated charcoal filter
C. after chemical analysis shows it is fit for consumption
D. through a solenoid operated three-way valve
