In this article discussed about the role of sugar melter in sugar industry process house and its capacity and design calculation. Also provided online calculator for its capacity calculation.
Sugar Melter Capacity Calculation | Sugar Melting Feed Liquor Calculation
The sugar melter simply can be defined as it a equipment in which dissolving of sugar takes place. Generally the sugar plants can be classified as Raw sugar plant, Refined sugar plant and white( Suphited ) sugar plants. All these type of sugar plants sugar melter is one of the essential equipment in process house.
According to sugar melter application it is called mainly two types.
- B and C sugar mellter or low grade sugar melter
- Raw Sugar melter
B & C sugar mellter:
According to boiling scheme adopted in sugar process, some or total low grade sugars i.e B sugar and C double cured sugar may be remelted. Its melt diverted to high grade massecuites.
B Massecuites cured in continuous centrifugals or high gravity batch machines. The B sugar can be used directly as a seed for A massecuite boiling and excess B sugar pumped to sugar melter for remelting the sugar and it is used in A boiling.
For C massecuites double purging is absolutely essential to reduce the colour load on final massecuite. The sugar after second purging is dissolved in a melter and melt used in “A” boiling.
For B and C sugar melting purpose using hot water, clear juice or syrup for melting
Raw Sugar Melter:
Affination process is the first step of refined sugar making. This process helps to remove as much of the molasses film surrounding the raw sugar. The affinated sugar sent to raw sugar melter to prepare melt for further process. For less colour of raw sugar can be directly sent to melter without affiniation process.
Raw sugar melting purpose using hot water or sweet water (low brix water) for melting
Sugar melter design parameters
There are two basic approaches to equipment for sugar melter
1. Horizontal cylindrical vessel with a horizontal rotating stirrer ( Horizontal sugar melter)
2. The second type is using number of vertical tanks in series or compartments in the same vessel and having top mounted stirrers in each tank ( Vertical sugar melter)
The Sizing of melter mainly depends on
- Size of the crystal to be melt
- Final melt brix requirement
- Temperature of the melter ( melt temperature )
For B and C sugar having the crystal size in the range of 150 to 350 micron. According to Peter Rein recommendations 15 to 20 minutes holding volume required for at 70 brix and 70 oC temperature.
For Raw sugar having the crystal size in the range of 250 to 650 micron. So for raw sugar melter required minimum 25 to 30 minutes holding volume required for at 70 brix and 70 oC temperature.
Calculation of melter feed requirement and its vapour line sizing
Example – 1: ( Using Clear juice for both magma and melter)
| S.No | Particulars | UOM | Values | Remarks |
| Required Data | ||||
| 1 | Crushing Capacity | TCH | 230 | |
| 2 | B sugar % cane | % | 5 |
4.5 to 6 % |
| 3 | C sugar % cane | % | 1.5 | 1 to 2 % |
| 4 | Rory & Powder sugar | % | 1 | 0.5 to 1.5 % |
| 5 | Brix of sugar | % | 95 | 90 to 98 |
| 6 | Magma mixer oultet brix | % | 90 | 88 to 92 |
| 7 | Final Melt Brix | % | 65 | 60 to 70 |
| 8 | Clear Juice |
% | 14 | Clear juice brix |
| 9 | Vapour temperature | oC | 110 | Consider 1st vapour |
| 10 | Velocity of vapour | m/sec | 30 | Consider 1st vapour |
| 11 | Clear Juice inlet temperature | oC | 90 | |
| 12 | Melt outlet temperature | oC | 75 | 70 to 80 oC |
| 13 | Inlet Magma Temperature | oC | 45 | 40 to 50 oC |
| Calculation part | ||||
| 1 | Specific heat of Melt (Cp ) | Kcal/oC | 0.65 | |
| 2 | Latent heat of vapour (λ ) | Kcal/kg | 532.51 | As per the steam table |
| 3 | Specific Volume of Vapour | M3/kg | 1.210 | As per the steam table |
| Magma | ||||
| 4 | Quantity of B seed + C seed | T/hr | 17.25 | 230 x (5+1.5+1)% |
| 5 | Clear juice required for Magma | T/hr | 1.135 | [(17.25 x 95) – (17.25 x 90)] / (95 – 14) |
| 6 | Final Qty of magma | T/hr | 18.385 | 17.25 + 1.135 |
| Melter for B and C sugar |
||||
| 7 | Clear juice required for melting | T/hr | 9.01 | [(18.385 x 90) – (18.385 x 65)] / (65 – 14) |
| 8 | Total Melt Quantity ( Q ) | T/hr | 27.397 | 18.385 + 9.01 |
| 9 | Vapour required | T/hr | 1.003 | Q Cp ∆T / λ |
| M3/sec | 0.337 | 1.003 x 1000 x 1.210 / 3600 | ||
| 0.405 | 20 % extra | |||
| 10 | Dia of the vapour pipe | mm | 131 | SQRT(0.405/(0.785*30)))*1000 |
| 11 | Melt holding volume required | M3 | 9.132 | 27.392 x 20 / 60 (20 min. retention time |
Note : In the above calculation clear juice temperature ( heat value) not consider. While using the clear juice vapour requirement for melter is very less and some times almost requirement is zero.
Example – 2: ( Using evaporated syrup for both magma and melter)
| S.No | Particulars | UOM | Values | Remarks |
| Required Data | ||||
| 1 | Crushing Capacity | TCH | 230 | |
| 2 | B sugar % cane | % | 5 | 4.5 to 6 % |
| 3 | C sugar % cane | % | 1.5 | 1 to 2 % |
| 4 | Rory & Powder sugar | % | 1 | 0.5 to 1.5 % |
| 5 | Brix of sugar | % | 95 | 90 to 98 |
| 6 | Magma mixer oulet brix | % | 90 | 88 to 92 |
| 7 | Final Melt Brix | % | 65 | 60 to 70 |
| 8 | Syrup using for melter | % | 55 | Syrup Brix |
| 9 | Vapour temperature | oC | 110 | Consider 1st vapour |
| 10 | Velocity of vapour | m/sec | 30 | Consider 1st vapour |
| 11 | Syrup Juice inlet temperature | oC | 50 | |
| 12 | Melt outlet temperature | oC | 75 | 70 to 80 oC |
| 13 | Inlet Magma Temperature | oC | 40 | 40 to 50 oC |
| Calculation part | ||||
| 1 | Specific heat of Melt (Cp ) | Kcal/oC | 0.65 | |
| 2 | Latent heat of vapour (λ ) | Kcal/kg | 532.51 | As per the steam table |
| 3 | Specific Volume of Vapour | M3/kg | 1.210 | As per the steam table |
| Magma | ||||
| 4 | Quantity of B seed + C seed | T/hr | 17.25 | 230 x (5+1.5+1)% |
| 5 | Syrup required for Magma | T/hr | 2.464 | [(17.25 x 95) – (17.25 x 90)] / (95 – 55) |
| 6 | Final Quantity of magma | T/hr | 19.714 | 17.25 + 2.464 |
| Melter for B&C sugar |
||||
| 7 | Syrup required for melting | T/hr | 49.29 | [(19.714 x 90) – (19.714x 65)] / (65 – 55) |
| 8 | Total Melt Quantity ( Q ) | T/hr | 69.00 | 49.29 + 19.714 |
| 9 | Vapour required | T/hr | 2.948 | Q Cp ∆T / λ |
| M3/sec | 0.990 | 2.948 x 1000 x 1.210 / 3600 | ||
| 1.189 | 20 % extra | |||
| 10 | Dia of the vapour pipe | mm | 225 | SQRT(0.405/(0.785*30)))*1000 |
| 11 | Melt holding volume required | M3 | 23.000 | 69.0 x 20 / 60 (20 min. retention time |
Note :
1. In the above calculation total syrup requirement is 2.46 + 49.29 = 51.75 T/hr. Here syrup brix having maintained below 55o then available quantity will be sufficient for melting the sugar. Otherwise it may be required some quantity of hot water or clear juice to maintained constant melt brix.
2. While using the clear juice/syrup for melter then it is better to use screener to strain out extraneous matter
3. In the energy conservation point of view some designers using 4th vapour as a heating medium for melter. If we using 4th vapour then operate melter under vacuum condition or using DCH (Direct Contact Heater) with melt recirculation pump.
Sugar melter automation
The main controlling parameters in the melter is Brix and Temperature. So two control loops are required in melter automation
1 . Brix transmitter and control valve for feed (sweet water or clear juice or syrup) inlet to maintained the constant melt brix
2. Temperature transmitter and vapour/ steam control valve to maintain the constant melt temperature.
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