In a vacuum boiling evaporator, the fresh water generated is pumped out by （）.

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• 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

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• 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 pum

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• 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

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• In a flash evaporator, scale as a result of higher than normal temperatures in most likely to occur in the （）

  A . second stage feed heater B . saltwater feed heater C . distillate cooler D . second stage vapor separator

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• 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 flashing B . scale formation is not a severe problem C . cold shocking is more effective in removing scale D . water purity is greatly increased at high capacity

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• The temperature of the refrigerant in the evaporator coil depends mostly upon the （）.

  A . refrigerant pressure in the evaporator B . cooling water temperature to the condenser C . heat load in the refrigerator compartment D . solenoid valve in the liquid line

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• The evaporating pressure in R22 vapor compression refrigeration plant should be （） atmospheric.

  A . below B . above C . equal to D . much larger tha

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• In practice, the refrigerant flow after the evaporator is designed to ensure that the vapor leaving the evaporator is slightly （）.

  A . saturated B . super-cooled C . wet D . superheated

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• When a vacuum boiling evaporator works, the hot jacket water will pass over the tube stack and （） the sea water passing through the tubes.

  A . dispose B . dissolve C . heat D . dissipate

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• The vacuum maintained in the salt water feed heater shell of a flash-type evaporator is generally accomplished by （）.

  A . a separate air ejector unit B . a direct unimpeded connection between second stage and salt water feed heater C . either by vacuum drag or an external line from the first stage via a fixed orifice D . the fixed orifice provided in the steam supply line

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• 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 surface

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• A vacuum is initially established in the first and second stages of a low pressure evaporator by the use of （）

  A . vacuum drag from the auxiliary condensate system B . individual vacuum pumps C . a single non-condensing air ejector D . a two stage air ejector

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• In a vacuum distillation system, the case is the higher the pressure, （）.

  A . the saturation temperature is higher B . the higher the saturation temperature C . the higher is the saturation temperature D . the saturation temperature is more high

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• Small droplets of water entrained in the flashed vapor produced in a flash-type evaporator, are removed by the （）

  A . spray pipes B . demisters C . condensers D . splash baffle

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• Under normal operating conditions, the highest temperature and pressure conditions existing in a flash-type evaporator will occur in the （）.

  A . first stage B . second stage C . distillate cooler D . salt water feed heater

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• A thermostatic expansion valve is properly controlling evaporator superheatAdjusting this valve to lower the superheat will result in a/an （）.

  A . evaporator pressure decrease B . evaporator coil over-feed C . evaporator capacity increase D . expansion valve diaphragm rupture

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• With a vacuum boiling evaporator, the remainder of sea water fed to the evaporator is pumped out by （）.

  A . a brine pump B . an air ejector C . a feed pump D . distillate pum

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• In which of the areas listed would you expect to find the highest salt concentration in a flash evaporator?（）

  A . Distiller air ejector cooling medium B . Saltwater heater discharge C . First-stage internal feed box D . Second-stage internal feed box

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• Because of the reduced （） in the vacuum boiling evaporator, some of the sea water boils as it flows through the tubes.

  A . temperature B . water level C . pressure D . rate of flow

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• The latent heat of evaporation is dissipated in the （） in a compression refrigeration system.

  A . evaporator B . condenser C . expansion valve D . compressor

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• In a vapor compression refrigeration the evaporating pressure is maintained constant by the action of the （）, which removes vapor from the evaporator at the same rate at which it is formed.

  A . evaporator B . compressor C . condenser D . none of the above

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• After being boiled in the boiling water, the coffee beans ____________.

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• In a flash type evaporator, all saltwater heaters are vented through individual vent cocks to the ______.

  A.saltwater heater shell B.second-stage condenser C.atmosphere D.second-stage flash chamber

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• Boil 0.5 g of thepowdered tablets for 2 to 3 minutes with 10 mL of 5 M sodium hydroxide, cooland add an excess of 1 M sulfuric acid; a crystalline precipitate is produced.To a solution of the precipitate in water add iron (III) chloride solution R1;a _______ colour is produced.

  A、turquoiseblue B、deep violet C、sandy brown D、smoky grey

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