Mill Mate rial Balanc e
C H A PT PT E R I I I
THE EXTRACTIONS
Sugar is categorized the kind of sweetener produced through the processing of raw material, material, such as sugar cane, beet, coconut, different kinds of palm trees and stevia leaves as well. We will discuss sugar; the sweetener that mainly produced by the sugar factories processing sugar cane as the raw material into a sweetener called ‘crystal sugar’. Sugar cane is one among the other plants that richly consist of sugar (saccharose). Looking to the materials consisting in sugar cane, they could be grouped into two portions, i.e. the juice and the fiber. The same grouping applies for the component if they are seen from the physical terms, terms, where the the sweetener (saccharo (saccharose) se) inhibits inhibits the cane cane juice. juice. To optimally extract the saccharose from the sugar cane, a lot of separation works have to be implemented especially separating the non-sugar content from the sugar juice. Indeed most of the works applied in sugar factory were mainly separating works, such as separating cane juice from the fiber containing the cane, separating the water content from the cane juice, separating the color, separating viscous material from the crystal containing in the massecuite and so on. The first phase of such a work is to separate the cane juice from its fiber, and this is to be done with the help of certain equipment such as ‘the mill’, ‘the diffuser’, ‘cane separator’, screw press’ and the others as well. In the case of separating cane juice from its fiber which containing the sugar cane with the use of mill, such as normally done in cane sugar factories; we knew the term of ‘extraction’. The sugar cane is extracted to separate its juice from the fiber. If good extraction is expected, we have to put additional water as imbibition / maceration to dilute the saccharose stickled around the fiber cells, makes it easier to be separated or extracted. Because cane juice is considered to consist of water and brix, then sugar cane as physically seen is considered as to consist of juice and fiber. Further sugar cane also known as to consist of water, brix and fiber, while the sugar content of the cane is normally expressed by the value of its polarization (%pol). (%pol). Based upon the above descriptions, then we have to know the basic measure of extraction, which in term of milling there should be at least 3 (three) parameters: §
Juice extraction
§
Brix extraction (HPB)
§
Sugar extraction (HPG)
The juice extraction, is the result of division between the extracted juice and the juice containing in the incoming / original material.
The Extractions
III-1
Mill Material Balance
The Brix extraction, is the result of division between the extracted Brix and the total Brix containing in the incoming / original material. The sugar extraction, is the result of division between the extracted sugar (polarization) and the sugar containing in the incoming / original material. The expression of extraction therefore can be in fraction or in percentage. We’ll have further the overview of extraction for the following tandem consisting of 4 units of mill. ej3 ej4 cane
Mill.I
Mill.III
Mill.II
water
Mill.IV b4
b1
ej1
b2
ej2
b3
ej3
ej4
mj
The system shown above called the cane juice mill extraction with compound imbibition. In order to determine the rate of extraction, we have to calculate the amount of cane juice extracted by each mill in the tandem. #
Let’s see at mill 1: Wim1 = the weight of incoming material (cane), W b1 = the the weight weight of of bagasse bagasse produced, produced, then:
Wej1 = the weight of juice extracted; Wim1 = W b1 + Wej1
hence:
Wej1 = Wim1 - W b1 ..........……........... ..........……...........………………………....... ……………………….................. ................. ...... (a)
And then at mill#2: Wim2 = the weight of incoming material, W b2 = the the weight weight of of bagasse bagasse produced, produced, then: hence:
Wej2 = the weight of juice extracted; Wim2 = W b2 + Wej2 ..............................……………………………............... (b) Wej2 = Wim2 - W b2 ….....................……………………………..................... (c)
The Extractions
III-2
Mill Mate rial Balanc e
#
Then at mill 3: But back to equation (b): Wim2 = W b2 + Wej2, Wim2 = W b1 + Wej3 Wej3 = W b2 + Wej2 - W b1 ....................… ....................……………………………....... …………………………................ ......... (d)
also: hence: If:
Wim3 = the weight of incoming material, W b3 = the the weight weight of of bagasse bagasse produced, produced, Wej3 = the weight of juice extracted, # Wej4 = the weight of juice extracted extracted by mill 4;
then:
Wim3 = W b3 + Wej3 Wim3 = W b2 + Wej4 Wej4 = W b3 + Wej3 - W b2 .......................……………………………............. (e)
also: hence:
We’ve been trying to define all the formulas of juice extraction in each mill, but only the weights #
#
of juice extracted by mill 1 and mill 2, which could be detected so far. #
The weight of juice extracted by mill 1 that is Wej1 in the equation (a), could be calculated by the following Brix method: Wej1 =
Wmj
bmj - b j2 b j1 - b j2
Where the above formula describes: Wmj = the weight of mixed juice which is known through its weighing or measured, bmj = the Brix degree of of mixed juice, b j1 b j2
#
= the Brix degree of mill 1 juice, = the Brix degree of mill#2 juice;
All the values of Brix degree were the results of analysis. #
Hence, the weight of bagasse produced by mill 1 that is W b1 can be calculated, because Wim1 that is the weight of cane crushed was known during its weighing. #
The weight of juice extracted by mill 2 is then: Wej2 = Wmj - Wej1 #
For the moment we can not calculate the weights of juice extracted by mill 3 {Wej3 on equation (d)} and the juice extracted by mill #4 {Wej4 on equation (e)}, because the weights of bagasse # # produced produced by mill 2 and mill 3 are not known. All unknown items will be defined by the new system of calculation for a complete mill material balance, balance, especially especially the formula formula for the weight of bagasse exhausted by the respective respective mill after mill#1 in the tandem.
The Extractions
III-3
