Application Forced Circulation Re-boiler Proprietary Process Liquid
Industry Chemical
Fouling Issue / Frequency

A steam-heated evaporation system recovers a volatile organic from a heavy organic solution laden with foulants. A hard, black scale that was forming in the upper 25% of the tubes was forcing the plant to switch two parallel once-through rising film evaporators with a clean pair every four to five days. When asked to increase throughput and simplify operations engineers considered installing a 2100-sq-ft falling film evaporator (FFE) to operate in series with the existing rising film evaporators (RFE). Although the combination system was expected to run approximately 10 weeks between cleanings, a better solution was needed.

Solution / Approach

A fluidized bed heat exchanger used as a re-boiler for an evaporator system to recover a volatile organic (82 m2)

Process Conditions Tube Shell
Medium Proprietary Liquid Condensing Steam
Pressure 5 barg 11.4 barg
Temperature In: 124oC
Out: 150oC
Condensing at 181.5oC
Flow 160 m3/h 788 m3/h
Dimensions
Number of Tubes 55
Length of Tubes 10.5 m
Diameter Tubes 47.5 mm
Particle Type Stainless Steel
Particle Size 2 mm
Results

More than 20 years in operation.
No cleanings per year required compared to the 70 cleanings per year with the conventional re-boiler (annual turnaround replaces cleaning every 4 to 5 days).
A significant cost saving results from the higher recovery of acetic acid and the more concentrated residue in the bottoms.
The re-boiler circulation rate has been constant, thus providing uniform tower operation and more total throughput.

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