This article explains the concepts of the Graining volume in batch pan and examples for calculation of the graining volume are discussed.
The Concept of Graining Volume of the Batch Pan
The graining volume is the volume of the pan up to the level of the top tube plate, the minimum volume at which the pan can operate.
This term “Graining Volume” is used to denote the minimum volume of massecuite, which must be introduced in to the pan before opening of steam valve. It is calculated corresponding to the upper surface of top tube plate. It is also referred as ‘footing volume’ of the pan.
Graining volume is generally expressed in percent of the working volume of that pan. It is varies from 35 to 45%. Generally, all types of massecuites graining are made with higher purity syrup or molasses and afterward pan is filled with low purity material. So lower graining volume is obviously of advantage for better purity control of massecuite. Also, low graining volume is helps to increase the crystal size.
However, some massecuites graining material preparation and developing of the massecuite with same material. In such a situation, the % graining volume is not necessary to be considered for purity reduction.
Present scenario to improve the circulation of the pan use short length tubes . If tube length of pan decreases, then increase in the calendria diameter for the pan with same heating surface. The increase in calendria diameter increases the graining volume of the pan.
In case of 800 mm tube-length pans, the graining volume increases up to 40 % to 42%. Such pans gives higher circulation in pans.
The Graining volume of the batch pan calculated by adding these volumes to the pan
-
- a) Bottom cone volume
- b) Bottom ring volume
- c) Total tube volumes
- d) Downtake Volume
e) Volume of the pan up to 50mm height from the top tube plate (It may not be required to add this volume while calculating the graining volume)
Example of calculation of graining volume single discharge type:
| Graining Volume of Batch Pan | ||||
| Sl.no. | Description | Formula | Values | UOM |
| Input Data | ||||
| 1 | Capacity of pan | 60 | T | |
| 2 | No. of tubes | N | 1306 | nos. |
| 3 | Tube thickness | t | 1.6 | mm |
| 4 | Tube Length | H1 | 750 | mm |
| 5 |
Tube OD | OD | 102 | mm |
| 6 | Dia of pan | D1 | 5600 | mm |
| 7 |
Dia of the down take | D2 | 2400 | mm |
| 8 | Height of the bottom ring | H2 | 50 | mm |
| 9 | Angle of bottom cone | α | 18 | Deg |
| 10 | Discharge Dia | D3 | 600 | mm |
| Graining Volume Calculation | ||||
| 1 | ID of the tube | ID = OD – 2xt | 98.8 | |
| 2 | Volume of massecuite in tubes | Q1 = 0.785 x ID x ID x H1 x N | 7.51 | M3 |
| 3 | Volume of down take | Q2 = 0.785 x D2 x D2 x H1 | 3.39 | M3 |
| 4 | Volume of the bottom ring | Q3 = 0.785 x D1 x D1 x H2 | 1.23 | M3 |
| 5 | Height of the bottom cone | h = [(D1 – D3)/2 ] x TAN α | 812.30 | mm |
| 6 | A1= |
0.785 x (D1)2 | 24.62 | M2 |
| 7 | A2= | 0.785 x (D3)2 | 0.28 | M2 |
| 8 | Volume of the bottom cone | Q4 = h/3 (A1+A2+√A1A2) | 7.46 | M3 |
| 9 | Graining Volume | Q1+Q2+Q3+Q4 | 19.58 | M3 |
Example of calculation of graining volume “W” type cone
| Graining Volume of Batch Pan (“W” Type cone ) | ||||
| Sl.no. | Description | Formula | Values | UOM |
| Input Data | ||||
| 1 | Capacity of pan | 60 | T | |
| 2 | No. of tubes | N | 1306 | nos. |
| 3 | Tube thickness | t | 1.6 | mm |
| 4 | Tube Length | H1 | 750 | mm |
| 5 | Tube OD | OD | 102 | mm |
| 6 | Dia of pan | D1 | 5600 | mm |
| 7 | Dia of the down take | D2 | 2400 | mm |
| 8 | Dia of a bottom inverted cone | D3 | 2200 | mm |
| 9 | Height of the bottom ring | H2 | 50 | mm |
| 10 | The angle of the bottom cone | α | 18 | Deg |
| 11 | Angle of the bottom inverted cone | Φ | 35 | Deg |
| Graining Volume Calculation | ||||
| 1 | ID of the tube | ID = OD – 2t | 98.8 | |
| 2 | Volume of massecuite in tubes | Q1 = 0.785 x ID x ID x H1 x N | 7.51 | M3 |
| 3 | The volume of down take | Q2 = 0.785 x D2 x D2 x H1 | 3.39 | M3 |
| 4 | The volume of the bottom ring | Q3 = 0.785 x D1 x D1 x H2 | 1.23 | M3 |
| 5 | Height of the bottom cone | h 1 = [(D1 – D3)/2 ] x TAN α | 552.36 | mm |
| 6 | A1= | 0.785 x (D1)2 | 24.62 | M2 |
| 7 | A2= | 0.785 x (D3)2 | 3.80 | M2 |
| 8 | Volume of the bottom cone | Q4 = h/3 (A1+A2+√A1A2) | 7.01 | M3 |
| 9 | Height of the bottom inverted cone | h2 = [( D3)/2 ] x TAN Φ | 770.23 | mm |
| 10 | The volume of inverted cone | Q5 = 1/3 x 0.785 x (D3)2 h2 | 0.98 | M3 |
| 11 | Graining Volume | Q1+Q2+Q3+Q4 – Q5 | 18.17 | M3 |
Online Calculator for calculating the Graining Volume in Batch pan
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