Evaporation
HRS Heat Exchangers uses a combination of shell and tube and scraped surface heat exchangers in their evaporation process. Both corrugated tube heat exchangers (K series) and scraped surface heat exchangers (Unicus© series) have been used effectively for evaporation and concentration of various fluids in different applications.
Evaporation with forced recirculation
A recirculation pump is used to pump the fluid through the evaporator (at many times the flow rate of the evaporator feed). A high fluid velocity is maintained and elevated heat transfer coefficients are obtained in the evaporator. The forced recirculation evaporator is of special interest for applications with viscous fluids. The higher the viscosity, the worse the heat transfer becomes. Therefore re-circulating with higher flow rates using the recirculation pump produces high heat transfer, enabling the evaporator design and surface area of heat transfer to be relatively small.
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Evaporation with forced recirculation - process flow sheet
Scraped surface evaporation
For many environmental applications, standard evaporation technologies (falling film etc) are not ideal to achieve the desired performance. As the concentration of solids increases during the evaporation process, the risk of fouling substances depositing on the tube wall increases. A fouled evaporator will drop quickly in heat transfer and efficiency. The result is underperformance and regular shutdown for cleaning. Plant shutdown is expensive in terms of maintenance and production costs.
The solution HRS Heat Exchangers proposes is the Unicus© series scraped surface evaporator. We have the capacity to supply evaporators with up to 100 square meters (1080 square feet) of heat transfer area. This allows us to provide solutions for heavy fouling applications in evaporation with high evaporation capacity.
Multi effect evaporation & integration with dryer plant
With multi effect evaporation efficient use of existing energy created within the process means a reduced running cost. The evaporated water in the first effect is used as heating media in the second effect. This process can be repeated several times so that 1 kg of steam can evaporate several kg of steam from the product. HRS Heat Exchangers applies multi effect evaporation wherever possible. Combinations of multi effect evaporation and steam compression (mechanical vapor recompression or thermo compression) can be supplied for further energy optimization.
Another possibility of energy optimization is combining an evaporator plant with a dryer plant. This solution works well for cases where an (environmental) waste stream is separated in solid phase and a liquid phase by mechanical separation (centrifuge, decanter). The solid phase is sent directly to an indirect dryer. The liquid phase is sent to the evaporators. As energy for the evaporators we take the evaporated water of the dryer plant. The concentrate from the evaporator is mixed with the solid phase prior to sending to the dryer minimising the volume of environmental waste in the most energy efficient way possible.
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Multi effect evaporation & integration with dryer plant
Applications
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Environmental
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Biomass and Biofuels
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Food industry
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Brine |
Digestate (from biogas plant)
| Fruit concentrate |
| Water
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Stillage (from bioethanol plant)
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Manure Food and agricultural waste
Sludge
Other effluents
Recommended Products
K. Industrial Multitube
DTI. Industrial Double Tube
Unicus®