There are six basic processes involved in sugar manufacturing: Preparation, Extraction, Clarification, Evaporation, Crystallization, Separation.
EVAPORATION OF CANE JUICE
The clarified juice that comes out from the Clarifier contains about 85-87 percent of water
and between 13-15 percent of solids. The crystallization of sugar cannot happen in solutions containing less than 70 to 80 percent of solids; because of this, evaporation is necessary to
concentrate the cane juice to obtain sugar crystals.
At the evaporation station, the clear juice is boiled in Multiple Effect Evaporators. BSI operates 10 vessels and commonly employs a quadruple effect with 4 vessels. The evaporators are heat vessels that transfer heat from steam to the juice.
Low pressure steam, from the exhaust of the steam turbines at Belcogen, is used to boil the juice in the first vessel. As the juice boils, water is converted into vapor thereby concentrating the juice. This juice passes into the second vessel.
The vapor, from the boiling of the juice in the first vessel, is then used to heat the juice in the second vessel resulting in a further concentration of the juice. All evaporator vessels are each heated by the vapor from the previous vessel. Therefore, every pound of steam introduced into the first vessel results in the evaporation of four pounds of water. At this point, the greater part of the excess water is removed to yield a concentrated juice called “Syrup”, containing 65 to 68 percent solids. The syrup must be concentrated further so that the sucrose in solution will form crystals of sugar, which is our topic for the next article.