Revolutionizing Sugar Industry By Converting Robert Evaporator Into Falling Film (TREBOR) Evaporator

The global Sugar Industry is embracing change by putting more emphasis on energy conservation & industrial improvements. Similarly, current situation of Pakistan’s Sugar Industry also demands the measures to make business profitable by improving the efficiency of existing equipment in the long run.


In the light of such concerns we would like to invite Pakistan’s Sugar Industry attention to the new idea, of converting existing Robert Evaporator into Falling Film TREBOR (Evaporators). The idea has the potential of saving upto 20 Million PKR,  and has been proposed by our principal consultant, M/S PRACON. (Germany)


The complete idea revolves around the basic principles, which govern Robert Evaporator & can been converted into FFE- TREBOR with the induction of circulation pump. It is designed on a special distributor nozzles to feed each tube with juice.

Following this mechanism, many sugar industries in Pakistan can now embrace this revolutionary technology which can be implemented at a low cost with the promising benefits. With the changeover of this operation method, the heating steam inlet and the vapor outlet are preserved in their original position along the condensate outlet. One of the recent successful subjected execution has carried out in Bedburg.


In order to comprehend the subject in detail, lets shed a light over the summary of proposed conversion.


The system works with “distributing nozzles” which are at top plugged in every single tube and distribute the juice on the inner tube wall.

The system is suitable for all falling film evaporators (new evaporators and used evaporators). It is a cost-effective solution because the “nozzles” are of plastic and are produced in heated forms as thermoplastics. These “nozzle juice distribution” makes it possible to make falling film evaporators from Robert evaporators.

  • It is proved that falling film evaporators have higher evaporation performances than Robert evaporators which work in rising film. The heat-transmission-coefficient of “TREBOR-FF-evaporators is higher compared to ROBERT-evaporators.
  • Par (ex.), the density of syrup at the out-let of the evaporator (effect) is 25% (Bx) than TREBOR will reach a heat-transmission which is 10 % better than ROBERT.


Similarly following better heat transmission will be reach by TREBOR, which will be higher (%age wise) than ROBERT.


35 20
45 30
55 40
65 50
75 45



  • The juice-retention-times in falling-film-evaporators like TREBOR are shorter than in rising-film evaporators (e.g. Robert or Kestner), especially in the last stages of the evaporation station. The color development depends on the retention-time and the temperature of the juice in the vessel. In TREBOR-evaporators the syrup- retention-time is about ¼ a (quarter) compared to ROBERT`S. The syrup is brighter.


This modification from rising-film (Robert or Kestner) into falling film “TREBO evaporators brings advantages, such as:


  1. It saves the costs for the purchase and the mounting of a new falling-film evaporator, costs approx. 150.000,- € (falling film evaporator with 1200 m2 heating area)
  2. It saves the expenses for modification works on steam-, bled vapors-, condensate- and juice pipes because for working with the a.m. “nozzles” distribution (now and ever named TREBOR distribution) the steam inlet, the bled vapors outlet and the condensate outlet of the “modified” existing evaporator remain unchanged where there are. Modifications are only required at the lower part of the evaporator.

Each apparatus would be considered separately.


  1. For the falling-film evaporator with its flow principle, the final concentration of the thin juice that enters the tubes at the top, is achieved at the lower tube end only. The average juice concentration while evaporating is also lower as for the Robert evaporator as well as the medium boiling temperature (lower boiling point increase. Thus, the medium temperature fall which is useable for the evaporation, is increased. Furthermore, for falling film evaporator, no hydrostatic effects decrease the evaporation. Consequently, especially in higher concentration range, the k-values are much better for the falling film evaporation than for the Robert evaporator.


Lastly, being a national representative of M/S PRACON in Pakistan in terms of subjected expertise, we look forward to arrange a Skype call in between our principal consultant and your worthy self to process with the subject further.

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