For a flash type evaporator, the seawater heater will have to maintain a enough temperature to minimize scale formation（）

单项选择题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

单项选择题Which one of the followings might not be employed to create vacuum for flash type evaporator? （）

A.high-pressure steam-driven air-ejector
B.motor-driven vacuum pump
C.water-motivated air eductor
D.centrifuge pump

单项选择题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.condenser
B.flashing device
C.lashing device
D.vacuum pump

单项选择题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 condensing
B.higher cooling
C.lower cooling
D.higher condensing

单项选择题Before the sludge in a purifier is ejected,（）

A.the oil feeding is stopped and replaced by admitting flushing water
B.the flushing water feeding is stopped and replaced by admitting oil
C.the feeding of dirty oil and flushing water is stopped
D.the feeding of dirty oil and flushing water is admitted