Abstract: In a process of and a system for liquefying air to separate its components employing a so-called compound fractionating column, the system includes a fractionating medium pressure column into which a part of feed air is introduced to flow therethrough as an upwardly flowing gas for contact with a returning liquid, so as to obtain nitrogen gas at the top thereof and change the returning liquid to liquefied air as it reaches the bottom thereof, a first condenser adapted for a heat exchange between a liquefied air of a reduced pressure, which has been obtained by allowing an expansion of the liquefied air available at the bottom of the medium pressure column, and the nitrogen gas obtained at the top of the medium pressure column, so as to liquefy the nitrogen gas to make use of it as the returning liquid for the medium pressure column, a second condenser adapted for a heat exchange between the remainder part of feed air and liquefied oxygen to evaporate the oxygen, and a fractionating low pressure column through

Abstract: In a continuous sugar evaporator-crystallizer having a plurality of evaporating-crystallizing vessels as stages, each evaporating-crystallizing stages being communicated one to another in series and being provided with a means for feeding an aqueous sugar solution, a heating means and a means for withdrawing generated steam, by feeding an aqueous sugar solution to each evaporating-crystallizing stage, heating the aqueous sugar solution in each evaporating-crystallizing stage, thereby evaporating water off the aqueous sugar solution and crystallizing sugar crystals, and withdrawing the generated steam from each of the stages, while feeding seed sugar crystals to the first evaporating-crystallizing stage and withdrawing the resulting sugar crystal slurry from the last evaporating-crystallizing stage, sugar crystals of high quality is obtained in the slurry with an effective suppression of occurrence of conglomerated sugar grains by providing sugar crystal distances of 0.26 to 0.