| 摘要 |
1346614 Refining and crystallising sugar W R GRACE & CO 20 April 1971 [13 May 1970] 10179/71 Heading C6B In a sugar refinery at least a portion of at least one of the usual internal recycle streams is diverted to an air crystallisation stage where it is crystallised upon recycled sucrose - containing particles to produce a particulate, substantially dry, free flowing product. As shown in Fig.2, raw sugar is washed and melted at 24 and the resulting liquor is passed through a line 25 including defecation, clarification and decolourising stages to vacuum pans 26 from which white granulated sugar and soft sugar are withdrawn at 27, 9 respectively. The affination syrup from stage 24 with, optionally, some concentrated sweet waters, is fed by line 33 to a remelt station 32 where it is boiled to form remelt sugars which are remelted and returned through line 34 to the beginning of the process, and the final molasses is discharged at 31. The molasses or last strike syrup from the vacuum pans 26, instead of being recycled as usual to the remelt station 32, is fed to an air crystallisation apparatus 29 where it passes through a metering pump 54, Fig.4, to a centrifugal spray disc 47 by which it is distributed as mist in an enclosure 46 to which air is admitted from a heater 52. Crystallisation of the syrup is assisted by recycled sugar particles fed from a conveyer 56 to the enclosure just above the disc 47. The dried product, which contains a small proportion of invert sugar and is white or brown depending on whether or not the syrup is decolourised before reaching the air crystallisation apparatus, is discharged at 57, the finestparticles being retained in a cyclone separator 60 and the remainder passing to an outlet 58. In a modification, the affination syrup in line 33 is fed to the air crystallisation apparatus and the last strike syrup from the vacuum pans 26 is recycled through the remelt stage 32, whilst in a further modification neither the affination syrup nor the last strike syrup is recycled, both being fed to the air crystallisation apparatus. |
