Process for purification of low grade sugar syrups using nanofiltration
AssigneeTate & Lyle Industries, Limited
InventorsMichael Donovan, Marc Hlavacek
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Abstract
A nanofiltration process for obtaining sucrose uses a feed syrup, such as molasses, that comprises sucrose and no less than about 3% by weight invert sugars (on a dry solids basis). The nanofiltration produces a permeate and retentate. The nanofiltration permeate will comprise invert sugars that have passed from the feed through the nanofiltration membrane, and preferably will also comprise ash from the feed. The nanofiltration retentate has a higher concentration of sucrose and a lower concentration of invert sugars than the feed syrup. Sucrose can then be crystallized from the nanofiltration retentate. The reduction of the invert content in the syrup facilitates crystallization and thus enhances sucrose recovery.
Claims19
A process for obtaining sucrose from a sucrose-containing syrup, comprising the steps of:
- (a) nanofiltration of a feed syrup that comprises sucrose and no less than about 3% by weight invert sugars (on a dry solids basis) using a nanofiltration membrane, whereby a nanofiltration permeate and a nanofiltration retentate are produced, wherein the nanofiltration permeate comprises invert sugars, and wherein the nanofiltration retentate has:
- (i) a concentration of sucrose that on a dry solids basis is higher than the concentration of sucrose in the feed syrup, and
- (ii) a concentration of invert sugars that on a dry solids basis is lower than the concentration of invert sugars in the feed syrup;
- and
- (b) recovery of the nanofiltration retentate.
A process for obtaining sucrose from molasses, comprising the steps of:
- (a) filtration of molasses that comprises sucrose and no less than about 5% invert sugars (on a dry solids basis) using a microfiltration or ultrafiltration membrane, whereby a first permeate and a first retentate are produced, wherein the first retentate comprises at least one impurity that was present in the molasses and is selected from the group consisting of colloids, polysaccharides, and color-forming materials;
- (b) nanofiltration of the first permeate using a nanofiltration membrane having a molecular weight cutoff of about 100-500 daltons, whereby a second permeate and a second retentate are produced, wherein the second permeate comprises more than about 75% by weight of the invert sugars that were in the molasses, and wherein the second retentate has a concentration of sucrose that on a dry solids basis is higher than the concentration of sucrose in the molasses;
- and
- (c) crystallization of sucrose from the second retentate.
Dependencies are inferred from the claim text.