The best processing conditions and typical characteristics of the state of the art and efficient clarifier
The best processing conditions and typical characteristics of the state of the art and efficient clarifier.
1. Introduction
The clarification process occurs in a clarifier. The mixed juice is kept in the clarifier and the impurities settle down. Two layers are formed; the upper layer contains a clear clarified juice and the bottom contains mud, which settles down due to a higher density. The clear juice (overflow) is sent to the evaporators to be converted to syrup and finally sugar. On the other hand, the mud (underflow) is pumped to the filtration station to recover the sucrose entrained in the mud.[1]
2. Purpose
The purposes of the clarification of sugar cane juice have been stated to be ideally, to obtain:
a) Maximum elimination of non-sugars
b) Maximum elimination of colloids
c) Low turbidity of the juice
d) Minimum color formation
e) Maximum rate of settling
f) Minimum calcium content of juice
g) Suitable pH of juice to avoid inversion of sucrose or decomposition of reducing sugar.[2]
3. Condition in clarifiers
Temperature is an important factor. The temperature in the clarifier should not be too low. According to the kinetic theory of matter, at low temperature, the flocs formed will move slowly this will affect the settling rate.
Temperature above boiling point is not good. Above boiling point, the juice will start to boil. This will create turbulences in the juice hence affecting the setting rate
Usually a temperature between 95-97°C is kept in the clarifier. [1]
4. Types of clarifier
i. Multi tray clarifier - Rapid Dorr
The MultiTray clarifier design contains several compartments which main objective is to increase the area to enhance the mud settling.
Volumetric capacity of this clarifier is in the order of 1.5 m3 /TCH.
Juice residence times of almost 1.1 hours to settle very light flocs. Longer residence time, the more sucrose are exposed for inversion. The table below shows the percentage inversion occurring for different residence time and
1. Introduction
The clarification process occurs in a clarifier. The mixed juice is kept in the clarifier and the impurities settle down. Two layers are formed; the upper layer contains a clear clarified juice and the bottom contains mud, which settles down due to a higher density. The clear juice (overflow) is sent to the evaporators to be converted to syrup and finally sugar. On the other hand, the mud (underflow) is pumped to the filtration station to recover the sucrose entrained in the mud.[1]
2. Purpose
The purposes of the clarification of sugar cane juice have been stated to be ideally, to obtain:
a) Maximum elimination of non-sugars
b) Maximum elimination of colloids
c) Low turbidity of the juice
d) Minimum color formation
e) Maximum rate of settling
f) Minimum calcium content of juice
g) Suitable pH of juice to avoid inversion of sucrose or decomposition of reducing sugar.[2]
3. Condition in clarifiers
Temperature is an important factor. The temperature in the clarifier should not be too low. According to the kinetic theory of matter, at low temperature, the flocs formed will move slowly this will affect the settling rate.
Temperature above boiling point is not good. Above boiling point, the juice will start to boil. This will create turbulences in the juice hence affecting the setting rate
Usually a temperature between 95-97°C is kept in the clarifier. [1]
4. Types of clarifier
i. Multi tray clarifier - Rapid Dorr
The MultiTray clarifier design contains several compartments which main objective is to increase the area to enhance the mud settling.
Volumetric capacity of this clarifier is in the order of 1.5 m3 /TCH.
Juice residence times of almost 1.1 hours to settle very light flocs. Longer residence time, the more sucrose are exposed for inversion. The table below shows the percentage inversion occurring for different residence time and
References: [1]Seebaluck. V,(2015). Lecture notes; Clarification [2]Komen.P.J, (1966)Factors in clarification. [online] Available from: http://www.assct.com.au/media/pdfs/20-66.pdf [Accessed 22 Feb 2015] [3]Santiago.A (2013) DESIGN AND IMPLEMENTATION OF A VERY SHORT RETENTION TIME FILTRATE CLARIFIER [online] Available from: http://etd.lsu.edu/docs/available/etd-10282013-134806/unrestricted/Grimaldo_thesis.pdf [Accessed 22 Feb 2015]