Revamp Forced Circulation Evaporator Waste Water Stream

Ref Revamp Forced Circulation Evaporator
ApplicationForced Circulation Evaporator Waste Water Stream
IndustryDyes Manufacturer
Fouling Issue / Frequency

The evaporator being revamped was the 1st effect of a 4-effect evaporator train to treat waste water from a plant that produces dyes for textile. This 1st effect experienced severe fouling by crystallization of a variety of sulfate salts. Effect 2 to 4 experienced some fouling but to a lesser extent. Due to fouling, within only 20 days of operation, the plant regularly lost more than 50% of its treatment capacity.

Solution / Approach

For the revamp into the self-cleaning configuration, the heat exchanger was equipped with an inlet channel to feed the particles and distribute them over all tubes. In between the heat exchanger outlet and the entrance of the flash vessel a particle separator was installed to separate the particles from liquid and transport them via a central down-comer back to the inlet. In the revamp the existing heat exchanger bundle was re-used, changing it from a 3-pass into an once-through configuration.

Process ConditionsTubeShell
MediumWaste Water Dyes ProcessCondensing Steam
Pressure2.2 bara1.59 bara
TemperatureIn: 107oC
Out: 108.63oC
In: 113.20oC
Out: 112.58oC
Flow900 m3/h2659 kg/h
Duty1646 kW



Number of Tubes


Length of Tubes

6 m

Diameter Tubes

34.9 mm (ID)

Particle Type


Particle Size

3 mm

After taking the plant back into operation, the evaporation capacity kept constant, which results in increased production, lower downtime and reduced maintenance cost.