This article aims to provide a basic informative guide to calculating the equipment capacities for essential components in the sugar refinery, such as the raw sugar melter, melt clarification system, deep bed filters, ion exchange resin system, pan section, centrifugal section, sugar drying, and grading.
The major unit operations in Sugar Refinery are as follows
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- Raw Sugar Storage / Handling
- Affination mixer, (Required if the raw sugar colour is high)
- Raw sugar melter
- Melt Clarifier ( First Decolourization ; Phospho- floatation Process or Carbonation process)
- Filtration (Deep Bed Filtration)
- Ion exchange resin ( Second Decolourization : Ion exchange resin, Powdered activated carbon & Granular activated carbon)
- Melt Concentrator
- Pans and crystallizers
- Centrifuging,
- Sugar dryer, Grading Drying & Packing
Refinery Production Capacity:
We assume Refined sugar production = 1,200 TPD (Tons per day)
Average Brix of operation – 60 ( 60 to 65% brix)
Recycle around filtration, liquor re-circulation, dryer and grading in sugar reprocesses is around 25%
Hence, raw sugar melt quantity = 1200 x 1.25 = 1500Tons/day = 62.5 Tons / hour
i.e 104 tonnes melt flow per hour = 84 m3/h (Considered density – 1.24 g/ml)
Raw sugar handling storage / Handling:
In back-end sugar refinery there are various types of conveyors are used for the transportation of raw sugar from the centrifugal section to the raw sugar melter. Generally, ribbon screw conveyors or grasshopper conveyors are used in raw sugar houses to transport sugar from centrifugals or driers to raw sugar storage bins or packing bins. The ribbon or screw conveyor consists of a spiral ribbon or screw that revolves in a trough, carrying sugar with it. The cross section of the trough is usually parabolic instead of U-shaped.
Affination Magma Mixer
The affination process marks the initial stage in the sugar refinery, utilizing high-colored raw sugar as the input material. This procedure entails washing, characterized by the removal of the adhering molasses film from the surface of the raw sugar crystal.
During the affination process, the high-colored raw sugar is combined with affination liquor, obtained through centrifugation in the same process. The mixture is then purged in a centrifugal machine with hot water washing after the syrup has been spun off. Following this stage, two distinct products emerge: affinated sugar and affination liquor.
The affinated raw sugar is diverted to the raw sugar melter, while a portion of the affination liquor is employed in the same process. The remaining quantity is sent to the recovery house for massecuite boiling.
Please go through the below link for more information about the material balance of the Affination Process in the Sugar Refinery Affination Process
Raw Sugar Melter:
The raw sugar melter’s aim is to generate a melt liquor at 60 to 65 Brix with a minimum temperature of around 75oC. It is recommended due to the potential for microbial activity at lower temperature and required to further process.
There are two main types of equipment for sugar melters:
Horizontal Sugar Melter: This approach involves a horizontal cylindrical vessel with a horizontally rotating stirring mechanism
Vertical Sugar Melter: The second type employs a series of vertical tanks or compartments within the same vessel, each equipped with a stirrer mounted at the top.
For Raw sugar with crystal sizes ranging from 250 to 650 microns. A minimum holding volume of 25 to 30 minutes is required to achieve a melt Brix of around 65 at a temperature of 70 °C”.
| S.No | Particulars | UOM | Values | Remarks |
| Inputs | ||||
| 1 | Refinery Capacity | TPD | 1200 | Tons per day |
| 2 | Brix of sugar | % | 99.9 | |
| 3 | Final Melt Brix required | % | 65 | 60 to 65 |
| 4 | Sweet water / hot water for melting | % | 0 | If used sweet water melting is considered brix. Otherwise, it will be zero, |
| 5 | Vapour temperature | oC | 1 10 | |
| 6 | Temperature of Sweet water/ hot water | oC | 50 | |
| 7 | Melter outlet melt temperature | oC | 7 5 | |
| 8 | Retention time of the melter | minutes | 30 | 25 to 30 min. |
| Calculation part | ||||
| 1 | Raw sugar melter capacity | TPH | 62.5 | Considered 25% extra capacity as per the re-circulation of sugar |
| 2 | Quantity of Raw Sugar to be melted | T/hr | 62.5 | |
| 3 | Sweet water/ hot water required for melting | T/hr | 33.56 | (62.5*99.9) – (62.5*65) / (65-0) |
| 4 | Total quantity of melt | T/hr | 96.06 | 62.5+33.56 |
| 5 | Final Qty of melt | M3/hr | 75.05 | The density of melt 1.28gm/ml |
| 6 | Holding the Volume of the raw sugar melter | M3 | 37.5 | As per the retention time |
| 7 | Specific heat of melt | Kcal/oC | 0.61 | 1-0.006*brix |
| 8 | Latent heat of the vapour |
Kcal/kg | 532.51 | as per Steam table |
| 9 | Vapour required | T/hr | 4.183 | As per the heat balance |
Raw Sugar Melter Online Calculator
Melt Clarifier ( First Decolourization ; Phospho- floatation Process or Carbonation process)
Here, we will discuss about capacity calculation for melt clarification by Phospho- floatation Process.
Buffer tank capacity : The buffer tank, also known as the untreated liquor storage tank helps to maintain the constant flow of liquor to feed the melt clarifier. Usually, the holding capacity of buffer tank will be considered around 30 to 40 minutes retention time of the melt.
Reaction tank: The reaction vessel requires a retention time of around 6 minutes (4.5 minutes for agitation tank + 1.5 minute for aeration tank) retention time with agitator and aeration for reaction.
Clarifier: The Flotation clarifier retention time will be provided around 35 minutes. Height of the clarifier having 1.7 to 1.75 mtrs and accordingly the diameter of the clarifier can be calculated.
Online Dosing Calculation for Syrup Clarification & Melt Clarification Systems Click Here
DEEP BED FILTER
In the deep bed filtration system, the static bed filter effectively eliminates suspended solids from the clarified melt as it traverses a meticulously chosen filter media. During this process, the suspended solids become entrapped within the media. At regular intervals, the accumulated solids are purged to ensure the cleanliness and optimal functionality of the filter media.
The Ion Exchange Resin System (IER) :
We assume Refined sugar production per day = 1,200 TPD
Recycle around pans, dryer, and liquid sugar processes is around 25%
Hence raw sugar melt quantity = 1200 x 1.25 = 1500Tons/day = 62.5 Tons / hour
i.e 104 tonnes melt flow per hour = 84 m3/h (Considered density – 1.24 g/ml)
Ion exchange resin capacity requirement is depends on service flow rate and colour load on ion exchange resin. The service flow rate is defined as the ratio of melt flow to bed volume (BV) of the ion exchange column. The will be around 2.0 to 3.0 BV/hr. It also depends on colour value of input liquor.
For example, if the IER capacity is 8 M3 (cell -1 having 4m3 & cell-2 having 4m3) then it can handle the melt flow rate as follows
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- For 3.0 BV/hr – 24 m3/hr
- For 2.5 BV/hr – 20 m3/hr
- For 2.0 BV/hr – 16 m3/hr
For easy and flexible operation purpose, the IER batteries capacity will be considered as 3nos. x 50% of their capacity. Therefore 2nos. of batteries are in operation and the other one is in regeneration.
Melt Concentration
As part of its steam-saving initiatives, melt concentration system was introduced as a double-effect or triple effect evaporator to concentrate the decolorized fine liquor before feeding to the pans. The Falling Film Evaporator or PHE type evaporators are specifically designed to handle high concentration melt liquor, boiled with low-temperature vapor. This design operates without hydrostatic head and maintains a minimum Delta T.
Fine liquor concentrate from 60⁰ brix to 72⁰ brix, offering the flexibility to adjust to further process requirements. The melt concentration system is not only facilitates steam savings in refinery pan boiling but also enhances pan capacity, contributing to overall operational efficiency.
Heating surfaces of melt concentrators: Will provide a separate article
Batch pans & Crystallizes for Refinery massecuite boiling
The boiling times considered for R1,R2 grade massecuites are 2.5 to 3 hours and for R3 & R4 grade massecuite are 3 to 3.5hrs.
Refinery massecuite quantity – The quantity is around 210% to 220% of the output sugar solids. ( If considered the R1, R2 & R3 grade massecuites). This increases by 20% if R4 massecuite boiling is considered.
Recovery House massecuite – The quantity of A, B & C massecuite will be around 20% to 25% on input sugar solids. The boiling hours to be considered as 3 to 4 hours as like raw sugar house massecuite boiling.
Assumed Refined sugar production per day = 1,000 TPD
The refinery massecuite quantity is 2,400 TPD (based on 240% of sugar solids). The massecuite ratios for R1, R2, R3, and R4 grades are 8:4:2:1, respectively. For R1, R2, and R3 grades alone, the ratio is 4:2:1. As per the ratio we can calculate the quantity of massecuite.
| Massecuite | Boiling Hours | Quantity of massecuite in Ton/day ( Say A ) | No. of strikes per day per pan (24/boiling hours) (Say B ) |
Quantity of massecuite per strike in Ton (A/B) | No. of pans required |
| R1 | 3.0 | 1280 | 8.0 | 160 | 100 Ton pans x 1 no.
80 Ton pans x 1 no. |
| R2 | 3.0 | 640 | 8.0 | 80 | 80 Ton pan x 1 no.
40 Ton pan x 2 nos. |
| R3 | 3.5 | 320 | 6.9 | 47 | |
| R4 | 3.5 | 160 | 6.9 | 23 |
Assumed Refined sugar production per day = 1,000 TPD
Raw massecuite quantity = 250 TPD ( Considered 25% on raw sugar solids)
| Massecuite | Boiling Hours | Quantity of massecuite in Ton/day ( Say P) | No. of strikes per day per pan (24/boiling hours) (Say Q ) | Quantity of massecuite per strike in Ton ( P/Q) | No. of pans required |
| A | 4.0 | 143 | 6.0 | 24 | 40 Ton pan x 1no. |
| B | 5.0 | 71 | 4.8 | 15 | 40 Ton pan x 1no. |
| C | 5.0 | 36 | 4.8 | 7 |
Crystallizers are to be provided for each pan individually. The capacity of the crystallizer is to be considered 10% extra of the respective pan capacity.
Centrifugal machine’s capacity requirement
We assume Refined sugar production = 1,000 TPD
Refinery massecuite quantity = 2400 TPD ( Considered 240% on raw sugar solids)
Quantity of massecuite = 2400/24 = 100 T/hr
The capacity of each machine – 1750 Kg/charge
Number of average cycles – 18 cycles/hr
Each Machine capacity – 1750 x 18 = 31.5 T/hr
No. of machines required – 100 / 31.5 = 3.17
Therefore, three centrifugal machines are required for Refinery Massecuite with one as a standby, requiring a total of four machines.
Sugar Dryer and Sugar grader
We assume refined sugar production per day = 1,000 TPD
Quantity of massecuite = 2400/24 = 100 T/hr
Crystal % massecuite = 55%
Sugar Quantity = 100 x 55% = 55 T/hr
Capacity of sugar dryer is to be considered around 60 T/hr. Therefore, consider two sets with capacities of 30 T/hr each.
Note: Actually sugar production is 40T/hr for 1000TPD refinery plant. However here considered 50% extra capacity because it is a single equipment and shall be absorbed loads and breakdowns in process. Also sugar house equipment capacity is always better to consider on maximum operating capacity of batch centrifugal machines as per the existing system. In the above example existing machines capacity is 4 nos. and its total massecuite curing capacity will be around 120 T/hr. Therefore, running all four machines might be necessary at times to account for breakdowns.
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Related Article:
Sugar Refinery | Raw melt decolourization Techniques for Refined Sugar Process
Affination Process in Sugar Refinery with Material balance Calculation
Sugar Melter Application in Sugar Factory | Sugar Melter design Calculation
Melt Clarification System Design Criteria for Sugar Refinery Process
Carbonation Process in Sugar Refinery and Raw melt decolourization process
Ion Exchange Resin Process In Sugar Refinery | Basic Concepts of IER Process
Color, Solids and Purity Balance of Refined Sugar Massecuite Boiling
Centrifugal section equipment Capacity Calculation in Sugar Industry
