Pan Section Capacity Calculation in Sugar Industry | Crystallization
The sugar crystallization process takes place in the pan section of the sugar plant. The equipment supply tanks, Batch/continuous pans, condensers, molasses conditioners, spray pond, crystallizers fall under the pan section.
Capacity of Batch/Continuous pans
The boiling times considered for A, B & C massecuites are 4 hours, 6 hours, and 8 hours respectively. For refinery massecuite,2 to 3 hours is considered.
Example:
The Crushing Capacity of the plant = 230 TCH
-
- “A” massecuite%cane = 25 to 30%
- “B” massecuite%cane = 12 to 13%
- “C” massecuite%cane = 6 to 8%
- ” A” Massecuite Quantity = 230 x 30% = 69 T/hr = 1656 T/day
- ” B” Massecuite Quantity = 230 x 13% = 30 T/hr = 720 T/day
- ” C” Massecuite Quantity = 230 x 8% = 18.5 T/hr = 444 T/day
While considering batch pans with 60 Ton capacity each
| Massecuite | Boiling Hours | No. of strikes per day per pan | Quantity of massecuite per strike in Ton | No. of pans required |
| A | 4 | 24 hours/4 = 6 | 1656/6 = 276 | 276/60 ≈ 5 nos. |
| B | 6 | 24 hours/6 = 4 | 720/4 = 180 | 180/60 = 3 nos. |
| C | 8 | 24 hours/8 = 3 | 444/3 = 148 | 148/60 ≈ 3 nos. |
While considering Continuous pans for all massecuite boilings
For continuous pans, 10% to 20% extra capacity is to be considered.
From the above
-
- For ” A” Continuous Pan = 69 T/hr x 110% ≈ 76 T/hr
- For ” B” Continuous Pan = 30 T/hr x 120% ≈ 35 T/hr
- For ” C” Continuous Pan = 18.5 T/hr x 120% ≈ 22 T/hr
Grain and Molasses ratio for A, B & C massecuites is generally taken as follows ( It depends on grain size and purity of material)
-
- “A” Grain to Liquor (syrup/melt/AL) ratio – 1: 1 to 2
- “B” Grain to Liquor (A heavy) ratio – 1: 2 to 3
- “C” Grain to Liquor (B heavy/ C light) ratio – 1 : 3 to 4
B massecuite purity online calculation sheet | Sugar Technology
C massecuite final purity calculation |Grain Quantity requirement for C CVP
| Massecuite | Boiling Hours | No. of strikes per day per pan | Quantity of grain required in Ton | Quantity of massecuite per strike in Ton | No. of pans required |
| A Grain | 4 | 24/4 = 6 | 1656/2 = 828 | 828/6 = 138 | 138/60 = 2.3 (70T x 2 nos.) |
| B Grain | 6 | 24/6 = 4 | 720/3 = 240 | 240/4 = 60 | 60/60 = 1 no. |
| C Grain | 8 | 24/8 = 3 | 444/4 = 111 | 111/3 = 148 | 37/60 ≈ 1 no. |
Thumb rules for finding the capacities of batch/continuous pans
Note: It is not accurate capacity but it gives approximate value instantly
Batch pans
-
- “A” Batch pan capacity in Ton – TCD x 0.06 ( Ex: 5000 x 0.06 = 300 T )
- “B” Batch pan capacity in Ton – TCD x 0.04 ( Ex: 5000 x 0.04 = 160 T )
- “C” Batch pan capacity in Ton – TCD x 0.03 ( Ex: 5000 x 0.03 = 150 T )
Continuous pans
-
- “A” Continuous pan capacity in Ton – TCD x 0.014 ( Ex: 5000 x 0.015 = 75 T/hr )
- “B” Continuous pan capacity in Ton – TCD x 0.006 ( Ex: 5000 x 0.006 = 30 T /hr)
- “C” Continuous pan capacity in Ton – TCD x 0.004 ( Ex: 5000 x 0.004 = 20 T /hr)
- “A” Grain pan capacity in Ton – TCD x 0.025 ( Ex: 5000 x 0.025 = 125 T )
- “B” Grain pan capacity in Ton – TCD x 0.01 ( Ex: 5000 x 0.01 = 50 T )
- “C” Grain pan capacity in Ton – TCD x 0.01 ( Ex: 5000 x 0.01 = 50 T )
Low Grade Massecuite Treatment in Sugar Crystallization Process
Sugar Seed Slurry Requirement Calculation for B and C massecuite
Types of Graining Techniques in sugar crystallization process | Pan Boiling
Pan Supply Tanks
-
- “A” massecuite feeding liquor (syryp/melt/A light) consider minimum 2 hours retention time
- “B” massecuite feeding liquor (A Heavy) consider minimum 3 hours retention time
- “C” massecuite feeding liquor ( B heavy/ C light) consider minimum 4 hours retention time
Example:
Crushing Capacity of the plant = 230 TCH
Syrup % cane – 25 to 30%
Melt % cane – 12 to 14%
A light %cane- 2 to 3%
A heavy%cane- 12 to 15%
B heavy%cane – 6 to 7%
C light%cane – 2 to 3%
Syrup + melt + A light = 43% (average) = 230 x 43% ≈ 100 T/hr
High grade massecuite supply tanks capacity = 100 x 2 hours = 200 / 1.25(density) = 160 M3 = 1600 HL
A heavy molasses quantity = 230 x 15% = 34.5 T/hr
A heavy supply tanks capacity = 34.5 x 3 hours = 103.5 / 1.3(density) ≈ 80 M3 = 800 HL
B heavy + C light molasses quantity = 230 x 10% = 23 T/hr
A heavy supply tanks capacity =23 x 4 hours = 92 / 1.3(density) ≈ 70 M3 = 700 HL
Thumb rules for finding the capacities of supply tanks in pan section
High grade massecuite feed materials ( Syrup + melt + A light ) supply tanks capacity in HL = TCH x ( 7 to 8)
Low grade massecuite feed materials ( A Heavy + B heavy + C light ) supply tanks capacity in HL = TCH x ( 7 to 8)
Molasses Conditioners capacity
For its capacity, consider extra 10 to 20% on molasses production
Example:
Crushing Capacity of the plant = 230 TCH
A heavy%cane- 12 to 15%
B heavy%cane – 6 to 7%
C light%cane – 3 to 4%
A heavy molasses quantity = 230 x 15% = 34.5 T/hr
A heavy molasses conditioner capacity = 34.5 x 110% = 38 T/hr
B heavy molasses quantity = 230 x 7% = 16.1 T/hr
B heavy molasses conditioner capacity = 16.1 x 110% = 18 T/hr
C light molasses quantity = 230 x 4% = 9.2 T/hr
C Light molasses conditioner capacity = 9.2 x 110% = 11 T/hr
Capacity calculation of crystallizers
Crystallizers are used for cooling and holding of the massecuite. Air-cooled type crystallizers are used for high-grade massecuites, receiving crystallizers of continuous pans and seed crystallizer. Water cooled crystallizers are used for low-grade massecuites for proper cooling and better exhaustion.
A – Massecuite – ( 2 hours cooling purpose + 2 hours curing purpose) – Air-cooled
B – Massecuite – ( 6 to 8 hours cooling purpose + 3 hours curing purpose) – Air cooled + water cooled
C – Massecuite – ( 20 to 24 hours cooling purpose + 4 hours curing purpose) – Air cooled + water cooled
Each crystallizer capacity should be 10 to 15% more than the existing pan capacity.
For example, if a 60 T (42 m³) pan is considered, then the capacity of crystallizer can be taken as 70 T (48 m³).
For an air-cooled type crystallizer is considered for “C’ massecuite then cooling time can go up to 72 hours. So, proper design of cooling elements used in crystallizers enables the cooling time to come down to 18 to 24 hours.
Application of Crystallizers in Sugar Industry | Crystallizer Capacity Calculation
Example:
The Crushing Capacity of the plant = 230 TCH
“A” massecuite%cane = 25 to 30%
“B” massecuite%cane = 12 to 13%
“C” massecuite%cane = 6 to 8%
” A” Massecuite Quantity = 230 x 30% = 69 T/hr
” B” Massecuite Quantity = 230 x 13% = 30 T/hr
” C” Massecuite Quantity = 230 x 8% = 18.5 T/hr
Crystallizer capacity for “A” massecuite
Quantity of “A” massecuite for (2+2) hrs = 69 x 4 = 276 Tons ≈ 300 Ton
Total volume of “A” crystallizers = 300 /1.45 = 206 M3 = 2060 HL ( sp.gr =1.45 )
So total capacity split is into a number of crystallizers and each crystallizer shall have 10 to 15% more capacity than that of the pan. Generally, total capacity of “A” massecuite crystallizers are made equal to total capacity of “A” pans.
Capacity of “B” massecuite Crystallizer
Quantity of “B” massecuite for (7+3) hrs = 30 x 10 = 300 Tons
Total volume of “B” crystallizers = 300 /1.5 = 200 M3 = 2000 HL ( sp.gr =1.5 )
The total capacity is split into water-cooled and air-cooled crystallizers in the ratio of 7 : 3 or 8 : 2
Crystallizer capacity for “C” massecuite
Quantity of “C” massecuite for (24 +4) hrs = 18.5 x 28 = 518 Tons ≈ 550 Ton
Total volume of “C” crystallizers = 550 /1.5 = 370 M3 = 3700 HL ( sp.gr =1.5 )
The total capacity is split into water cooled and air cooled crystallizers in the ratio of 8 : 1
Vertical Crystalliser Design Calculation for Sugar Massecuite Cooling
Concepts of Vertical Crystallizer in Sugar Plant | Mono Vertical Crystallizer
Vacuum crystallizers :
The capacity of Vacuum crystallizer for A, B & C massecuites should be equal to the capacity of existing batch pans used for grain/footings of the massecuite. usually, one crystallizer per massecuite is considered.
Capacity of condenser
Coefficients of Evaporation rate for batch pans depend on the purity of material and hydro-static head of the massecuite. Hence, if the massecuite level increases in pan then the evaporation rate will decrease.
As per Mr. E.Hugot, the evaporation rates in kg/m² /hr are as follows
| Initial | Final | |
| Footing Pan | 85 | 17 |
| A-Masseccutie | 71 | 32 |
| B-Masseccutie | 46 | 11 |
| C-Masseccuite | 36 | 17 |
For condenser capacity calculations, batch pan evaporation rates are to be considered between 50 to 60 kg/m² /hr, and for continuous pans between 20 to 30 kg/m² /hr
Average evaporation rate in Batch Pans
A massecuite – 60 kg/m² /hr ,
B massecuite – 55 kg/m² /hr &
Cmassecuite – 50 kg/m² /hr
Average evaporation rate in Continuous pans
A massecuite – 30 kg/m² /hr ,
B massecuite – 25 kg/m² /hr &
C massecuite – 20 kg/m² /hr
Example:
If the heating surface of a 60 MT batch pan is 282 m², then the condenser capacity required is
282 m² x 50 kg/m² /hr = 14100 kg/hr ≈ 14.1 T/hr
If the heating surfaces of a 35 MT/hr continuous pan is 650 m² , then the condenser capacity required is
650 m2 x 25 kg/m² /hr = 16200 kg/hr ≈ 16 T/hr
Injection water System and Condensers
The vapour condensation quantity is that of vapour from pan section and the evaporator last effect.
Vapour produced from pan section = 18 to 25% on cane ( For back-end refinery plants, it goes up to 28% on cane)
Vapour produced from last effect evaporator body = 5 to 8 % on cane
Water required for condensing the vapour is calculated based on the cooling water ratio.
= Total heat of the vapour = 621 Kcal/kg @ 55 0C
Definitions in Steam Properties and Online Steam Table For Saturated Steam
To = Condenser outlet warm water temperature in 0C
Ti = Condenser inlet cold water temperature in 0C
Example:
Crushing Capacity of the plant = 230 TCH
To = Condenser outlet warm water temperature = 47 0C
Ti = Condenser inlet cold water temperature = 36 0C
So, Total vapour quantity for condensing = 230 x 33% = 80 T/hr
Cooling water ratio = (621 – 47) / (47 – 36) = 52.2 T/hr
i.e, 52.2 tons of water is required for One ton of vapour.
Total water required for condenser = 80 x 52.2 = 4176 T/hr
Condenser System for vacuum creation and their types with design criteria
Injection water pump capacity
Operating Injection water pump capacity = 4000 M3/hr
Installed Injection water pump capacity = 50 % more than the requirement = 4000 x 150% = 6000 M3/hr
( Split the total capacity into 2 x 50% capacity of the pumps and 1 x 50% as a standby)
Spray pond capacity
Theoretically, 750 kg/hr of warm water requires 1 m² of area of spray pond.
As per the latest trends of designs, 900 to 1000kg/hr of warm water requires 1 m2 area of spray pond.
Spray Pond area required = 4000M3/hr / 900 kg/hr
= 4000 x 1000 / 900 = 4444 m2 ≈ 4500 m2
Sugar Plant Capacity Calculation
Pan Section/ crystallization
Centrifugal section & Sugar House
