| 摘要 |
A method for removing ash from sugar containing solutions comprises contacting the sugar containing solution against one side of an ultrafiltration membrane (37), contacting the other side of the ultrafiltration membrane with a stripping fluid (38) to strip away monovalent ions and low molecular weight sugars which pass through the membrane. The stripping fluid is contacted at high pressure against one side of a nanofiltration membrane (43) which allows passage of monovalent ions and water only. The deashed retentate can be returned to the sugar containing solution, pass through an ion exchange column (47, 48) or cause to contact one side of a high pressure ultrafiltration membrane (76) which allows passage of water monovalent ions and low molecular weight sugars. The permeate (78) from the high pressure ultrafiltration membrane can be subjected to ion exchange (79) to provide a liquid sugar having a low ash content while the retentate (77) can be evaporated to a sugar product. The use of the semipermeable membranes allows efficient deashing of sugar containing solutions (i.e. sugar cane or sugar beet solutions) which improves the recovery of crystalline sugar and a quality of the sugar from the solution. |
