Exploration • Drilling • Field Services
Fig. 1. The falling film evaporator proved to be the best solution for the factory.
Falling film evaporation A
Johan van der Kamp reveals the most efficient energy optimisation for exothermal processes.
s a sector that is constantly searching for sustainable solutions, the oil and gas industry regularly uses waste heat boilers to win back residual heat at high temperatures. Bronswerk Heat
Transfer is an expert in this technology and it offers an innovative solution that also allows for heat recovery at low temperatures.
When one of its customers was building a new
factory, it was decided to raise the temperature of the process so that the released heat could be usefully applied, that heat now being used to create ‘vacuum steam’. Steam compression then produces a higher pressure and temperature so that the steam can be incorporated in the process cycle. Tis reduces the process demand for external heat, and much less heat has to be removed by means of cooling towers. Te product of the exothermal process enters at a temperature of 110°C and must be cooled down to 90°C. On one hand, the steam pressure in the steam generator is set as high as possible to achieve the steam condition that requires the least possible driving power from the compressor. On the other hand, excessive steam pressure would produce too small a temperature difference between the heat
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source and the steam, which would result in a much larger required heat transfer surface so that the heat exchangers would become too expensive. Moreover, the process medium has a high viscosity, which results in the wall heat transfer of this medium to be low. Tat is why it is important to find an evaporation temperature as close as possible to 90°C, but with sufficient driving force to realise an efficient design in terms of size and price – the search for optimisation. Tree solutions were studied to establish how steam can be generated in the most efficient way. Te first is the Termosyphon reboiler. Tis is
a vertical heat exchanger with the viscous process medium on the outside of the pipes, and the water/ steam mixture inside. Alongside the vertical heat exchanger there is also a separation tank. Te water
Fig. 2. The Kettle type reboiler system.
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