Milk of Lime in sugar Industry | MOL System Capacity Requirement

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 O $\rightarrow$ 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 65^oC .

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.

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7 thoughts on “Lime Properties for Sugar Industry | MOL Preparation Unit”

Rajendra Tatoba Shirdhone

(July 19, 2022 - 3:22 pm)

Good information sir thank you Sir

Pravin magdum

(August 17, 2022 - 3:35 pm)

Sir please provide information about juice rotary screen capacity and related calculations.
You are doing excellent work which is helping to much to all

siva alluri

(August 20, 2022 - 1:41 pm)

We will provide soon

op khandelwal

(November 25, 2022 - 2:18 pm)

MOL tank stirrer rpm

(December 2, 2022 - 2:43 pm)

24 to 28rpm

Baqa mohammad

(May 4, 2023 - 9:58 am)

Why white scale is formed in Refine pan in defication remelt phosphitation (talofloc process with deep bed filters)
waiting you reply pl
Thanks

(September 7, 2023 - 8:56 am)

How much & Why CaO content in mix juice and clear juice in sulphation & defication process.

Lime Properties for Sugar Industry | MOL Preparation Unit