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| Product : |
Cane sugar solution |
| Feed : |
108,768 kg/h, 65.6 °Brix |
| Concentrate : |
94,757 kg/h, 75.3 °Brix |
| Evaporation : |
14,011 kg/h |
| MVR motor : |
2 x 240 KW |
| Steam : |
nil |
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For concentratrion of dairy products such as milk and whey, only one stage MVR can compress the evaporated vapor for 6∼7℃ temperature elevation that must be sufficient because there is no boiling temperature rise to the concentrated solution over the evaporated vapor temperatre, i.e. BPR = 0℃.
However, the products consisting of low molecuar weight solute such as sugar and hydrocarbons differently to proteins have boiling point rise of 5∼10℃ proportional to concentration, thus one stage MVR must not be sufficient to have a good temperature gradient between shell and tube side.
The above illustrates the evaporator concentrating cane sugar solution from 65.5 °Brix to 75.3 °Brix without consuming a fresh steam from boiler except during a start-up stage of 20∼30 minutes. The most of evaporated and compressed vapor is condensed in the shell side of the evaporator that a very small condensing duty is required.
This two stage MVR elevates the evaporated suction temperature by 14℃ to provide 6∼8℃ temperature gradietnt between heat exchange surface of the evaporator. |
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Descriptions |
Unit |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
Medium |
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Feed |
Solution |
Solution |
Solution |
Discharge |
Steam |
Water |
Water |
Mass flow |
kg/h |
10,000 |
7,177 |
4,465 |
3,248 |
2,400 |
1,550 |
9,166 |
120,000 |
Total solid |
wt% |
12.0 |
16.7 |
26.9 |
36.9 |
50.0 |
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Temperature |
℃ |
74 |
74.2 |
67.8 |
62.1 |
42.6 |
170 |
55 |
32 |
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This reference is 4-effect falling film evaporator built in 2004, heated by TVR for concentrating 12 wt% coffee extract up to 50 wt% total solid before spray drying process.
For the total water evaporation of 7,600 kg/h, 1,550 kg/h motive steam is used that steam efficiency is only 0.2, close to 5-effect system.
Since a TVR can replace one effect evaporator, it sould be always recommended to put a TVR in multi-effect evaporator system in order to realize less investment for the same economy, unless boiling point rise is less than 5℃. |
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