IV Process description
Based on glucose syrup of DX96,DS32% after ion exchange as raw material, through the process of Nanofiltration membrane separation, vacuum concentration ,PH adjustment, hydrogenation, decolorization, press filtration, ion exchange, vacuum concentration,vacuum hyperconcentration,
granulation drying, to get 98.0～98.8% food grade γ-style crystalline sorbitol which the moisture <0.4％.
4.1 Nanofiltration membrane separation
The concentration of glucose syrup after ion exchange is 32～33％, DX≈96.5, through the Nanofiltration membrane separation it will get high pure glucose syrup which the concentration will be 24～25％ and DX>99.3(DS extraction rate will be about 50%),and then sent it to the next process. The concentration of membrane trapped syrup is 38～43％, DX is about 93.70,the syrup will be sent for production line of F55.
4.2 Vacuum concentration
The high purity glucose syrup after Nanofiltration membrane separation will be sent to multi-effect vacuum falling film evaporator to remove part of water that the concentration will be about 50%.
4.3 PH adjustment
Add some NaOH into the glucose syrup to adjust the PH to be 7.5～7.8
4.4 Hydrogenation
Sent the syrup to high pressure autoclave, it will react with hydrogen under the aid of Ni-Al alloy catalyst to get sorbitol. The hydrogenation adopts batch type ,reaction under low pressure（4.5MPa）catalyst settle in the autoclave mode.
4.5 Decolorization&press filtration
The hydrogenated solution contains some colored impurity caused by the high temperature of the glucose syrup during hydrogenation, add some activated carbon in the liquid to remove the colored impurity. The activated carbon in the hydrogenated solution is then filtered out together with the colored impurity adsorbed by the plate and frame filter press, the liquid will become clear and transparent,part of the Ni-Al alloy catalyst inside the solution will be filtered out at the same time.
4.6 Ion exchange
The liquid after decorlorization will go through the cation ion exchange column , anion ion exchange column, mixed bed to remove the cation and anion inside the liquid, so that the inorganic impurities (including the residue is N- Al alloy catalyst basically filtered ).
4.7 Sorbitol vacuum concentration
The liquid after ion exchange will be sent to the multi-effect vacuum falling film evaporator to remove part of water that the concentration will be increased from 50% to 80%.
4.8 Sorbitol vacuum hyperconcentration concentration
80% concentration sorbitol syrup will go through the single-effect vacuum evaporator for further removal of the water that the concentration will be increased from 80% to 98.5%.
4.9 Granulation drying
98.5% concentration sorbitol will go through the granulation dryer to get γ-style crystalline sorbitol that the moisture decreased to under 0.4% .
4.10 Packing
Pack the finished product γ-style crystalline sorbitol in different size and way according to the market need for convenient transportation.