Lime Properties for Sugar Industry | MOL Preparation Unit

Properties of Lime and its Application of Sugar Process | Equipment’s and its Capacity of MOL Preparation

LIME: 

Lime is the one of the main important reagent in juice clarification such as defecation , sulphitation, carbonation process. The lime is the cheapest and most required clarifying agent .

The consumption of lime in different process is as follows

In Defecation Process –  0.08 to 0.12% on cane

In Sulphitation Process – 0.14 to 0.20% on cane

The availability of lime in different forms like quick lime , lime stone and hydrated lime

The standards specification for quick lime(Cao) , lime stone(CaCO3) and hydrated lime[Ca(OH)2] are as follows.

    Lime stone Quick lime Hydrated lime
Cao 55 to 56% 80 -95% 70-76%
Mgo 0.5-2% 0.3-2.5% 0.5-2.0%
Co2 33-44% 0.5-1.5% 0.3-0.7%
Sio2 0.5-2.0% 0.2-1.5% 0.2-0.5%
Al203 0.2-0.5% 0.1-0.5% 0.1-0.2%
Fe2o3 0.1-1.5% 0.1-0.5% 0.1-0.2%
H2o 0.2-1.5% 0.1-0.4% 0.1-0.2%

Milk of Lime Preparation:

CaO is  a strong base and very reactive compound. It combines with water evolving heat & produces calcium hydarte.

CaO + H2\rightarrow Ca(OH)2 + 15.54 Kcal

(Calcium Oxide) + (Water)  \rightarrow (Calcium hydraoxide) + ( Heat)

The atomic weight of the above equation ( Where as Ca= 40; O= 16; H= 1)

(40 + 16) + (2+16) \rightarrow  74
56 + 18 \rightarrow  74

From the above equation we can understand 56 units of CaO plus 18 units of H2O results in 74 units of Ca(OH)2.

It means the ratio of hydroxide to CaO is 1.32 (74 ÷ 56). This means  1 Kg of CaO and 0.32 Kg of water will produce 1.32 Kg of Ca(OH)2, This is the minimum water required for preparation of calcium hydroxide. So calcium hydroxide contains 75.7% CaO and 24.3% H2O.

The reaction is exothermic and heat is evolved during reaction.

Solubility of Ca(OH)2 in water is very low as one part of Ca(OH)2 dissolves in 790 parts of water, but the solubility of CaO in sugar solution increases with concentration of sucrose but decreases as temperature rises.

The milk of lime prepared in the factory consists of fine suspension of Ca(OH)2 in water besides the hydroxide in solution.

White suspension is MOL. This slaked lime is sparingly soluble in water. Solubility of lime is 0.12% at room temperature & 0.08% at 65oC .

Lime is hygroscopic in nature and forms Ca(OH)2 If expose to the atmosphere, it losses its activity.

Under moist conditions lumps of lime exposed to atmosphere crumble to small pieces and are disintegrated. Prolonged exposure of lime to atmosphere results in formation of calcium carbonate due to reaction with CO2.

Hence lime should be fresh, properly burnt and packed to avoid exposure to atmosphere. A good quality lime immediately swells-up, heat is evolved and breaks if water is poured over the lump of lime. This is a crube method of judging the quality.

The CaO content of different concentrations of milk of lime expressed in terms of Brix or Beaume. Generally, industry people follows Beaume method.

At different brix the content of Cao in MOL is as follow as.

Brix   Grams Cao/ 1000ml

5.4     26

7.2     36

9.0     46

10.8   56

12.6   65

14.4   75

18      94

21.7   115

27.2   148

At different Beaume the content of CaO in MOL is as follow as.

Degree Beaume Density (gm/ml) Grams CaO/Lt CaO Percentage by weight
1 1.007 7.5 0.75
2 1.014 16.5 1.65
3 1.022 26 2.55
4 1.037 36 3.50
5 1.045 46 4.43
6 1.052 56 5.36
7 1.060 65 6.18
8 1.067 75 7.08
9 1.075 84 7.87
10 1.083 94 8.74
11 1.091 104 9.60
12 1.1 115 10.54

Milk of Lime (MOL) Preparation System Capacity Requirement

 

S.No Description Values UOM Remarks
Input Data
1  Crushing rate 230 TCH  5000TCD @ 22hrs basis
2  CaO requirement 1.2 Kg of CaO/TCH  Generally,
0.9 to 1.3 for sulphitation
0.5 to 0.8 for Defication
3  CaO % in lime 75 %  Depends on Lime quality
4  Beaume of Milk of Lime (MOL) 7 Deg.  7 to 10 Deg
5  Holding volume of MOL 12 hrs  Min. 8 hrs & Max 12 hrs
Result
1  Lime % cane 0.16 %  1.2 x 1000 / 75% 

0.14% to 0.18%

2  Lime requirement 368.0 Kg/hr 230 x 0.16%
3  MOL Preparation Unit Capacity 1200 Kg/hr  Considered 8 hours of operation per day
4  CaO in MOL 65 gm/lt. 368 x 24/8

As per the above table by considered Beaume

5  Milk of lime required 4246 Lts / hr   230 X 1.2 x 1000 /65
6  Milk of lime required 18.46 Lts /TCH  4246 /230

As per considered Beaume

7  MOL tanks holding capacity 51.0 M3 4246 x 12 /1000
8  MOL tanks holding capacity 260 HL x 2 nos. 51 x 10 /2

 

Calculation for the Identifying Shock Lime Connection to Juice Sulphitor

S.No Description Values UOM Remarks
 Input Data
1  Crushing rate 230 TCH  5000TCD @ 22hrs basis
2  Sulphited Juice% 115 %  Include filter juice
3  Shock lime time 9 Sec  8 to 12 sec
4  Juice inlet line dia 400 mm  Juice Pipe dia which is going from absorption tower to sulphitor bottom cone feed
5  Density of juice 1.06 gm/ml
 Result
1  Juice flow rate 249.53 M3/hr 230 x 115% /1.06
2  Volume of juice for shock lime 0.62 M3 249.53 x 9 / 3600
3  Length of the pipe line 4.97 Mtrs   0.62 /(0.785x400x400/1000000)

Hence Shock lime connection is to be provided 5 meter of distance from the juice inlet point of the juice sulphitor feed line.

Properties of Lime and Its application of sugar process | Equipment's and its capacity of MOL Preparation | At different Beaume the content of CaO in MOL | At different Brix the content of CaO in MOL | Milk of Lime (MOL) Preparation System Capacity Requirement | Calculation for the Identifying Shock Lime Connection to Juice Sulphitor Milk of Lime(MOL)in Sugar Industry

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Post Author: siva alluri

The aim of this Blog "sugarprocesstech" is Providing basic to advance knowledge in sugar process industry and providing maximum calculation regarding capacity and equipment design online calculators .

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