| Multiple effect evaporation systems are very | | | | much more waste water than permissible. The |
| common in the sugar industry. They find their use | | | | quantity let out is many times more because the |
| in concentration of liquids through multiple or | | | | erring industries 'dilute' the effluents before letting |
| repeated use of higher temperature vapours | | | | out to show that they comply with environmental |
| originating from a single point application of live | | | | regulations. |
| steam which is generally dry and saturated. | | | | Environmental protection authorities are becoming |
| Norbert Rillieux is credited with a patent for the | | | | increasingly intolerant, now-a-days, against polluting |
| first triple effect evaporator which was installed in | | | | industries, thanks to the intervention of courts of |
| a Louisiana sugar factory in 1843. It is incredible | | | | law and environmental activists. However, a lot |
| that Rillieux had such an advanced plant working | | | | needs to be done, especially, by the erring |
| over 100 years ago. | | | | industrialists themselves. Some of the progressive |
| Simply put, this concept theoretically means from | | | | and responsible ones have seen the utility and |
| a unit mass of low pressure steam, one can | | | | benefit of pollution control and water conservation |
| evaporate almost the same amount of vapour | | | | by installing multiple effect evaporators. |
| from a solution; the vapour emanating from the | | | | Evaporators are simple to construct and do not |
| solution is used to further evaporate the solution | | | | cost a great deal of money. They are rugged and |
| in another vessel and so on infinitely. Practically, | | | | robust. They are available in various designs like |
| this is not possible due to changes in the physical | | | | short-tube evaporators, long-tube evaporators, |
| properties of the solution that gets progressively | | | | natural circulation evaporators, forced circulation |
| concentrated leading to lower heat transfer rates. | | | | evaporators, climbing film evaporators, falling film |
| Thus, a triple effect evaporation system (that is, | | | | evaporators etc. Several engineers have |
| three evaporators in series connected to one | | | | contributed to our wealth of knowledge of these |
| another) can generate about 2.5 to 2.7 kilograms | | | | systems, notable being Robert, Kestner, Rillieux |
| of vapour from one kilogram of steam. In other | | | | etc. |
| words, the solution gets concentrated in the same | | | | The material of construction used varies from |
| proportion, more or less. | | | | cast steel to even titanium. The choice depends |
| In the current world scenario of depleting ground | | | | upon the properties and nature of the liquid to be |
| water sources, it is inevitable that water is | | | | concentrated. A question arises - is the |
| conserved to the fullest extent. In spite of so | | | | concentrated syrup not more dangerous the dilute |
| many regulations, in almost all countries one can | | | | effluent? The answer would be that by means of |
| find people throwing away water wastefully, | | | | multiple evaporation, we are seeking water |
| never bothering to reduce unwanted and | | | | recycling and re-use. The concentrated syrup |
| unnecessary consumption or to think of recycling. | | | | should be dried into powder form or it should be |
| The industries are the worst culprits in this regard. | | | | burnt (if it is carbonaceous) in boilers like it is being |
| Many process and manufacturing industries | | | | done with spent wash generated from ethanol |
| consume gallons and gallons of water and let out | | | | distilleries in China and India. |