Defoamer for Vacuum Evaporation Water Treatment: A Practical Solution to Foam Problems

In vacuum evaporation water treatment, foam issues are frequently underestimated. As system vacuum increases, bubble stabilization time extends, leading to foam accumulation, false liquid level readings, vapor entrainment of droplets, and even equipment corrosion. Conventional defoamers fail quickly under high temperature, high shear, and negative pressure conditions, requiring frequent re-dosing, which increases costs and disrupts continuous operation. 

Our observations indicate that the core triggers of foam include residual surfactants in feed water, saponified substances formed in alkaline water, and micro-bubble aggregation caused by gas release during evaporation. For such scenarios, Chemi Tech has developed a defoamer specifically for vacuum evaporation, addressing three key pain points: defoaming speed, durability, and high-temperature tolerance. 

The concrete solution consists of four steps. Step one: System diagnosis. Install online foam monitoring probes at the evaporator feed inlet and circulation pipeline, recording foam height and density continuously for 72 hours to identify peak foam outbreaks. Step two: Product selection. Based on water quality analysis (e.g., conductivity, surface tension values), match the appropriate HLB value defoamer product to avoid emulsion breaking or over-dispersion. Step three: Precise dosing. Use a metering pump to inject at the feed pump outlet in a continuous micro-dose manner, with initial dosing at 50-200 ppm, and adjust to steady state based on foam layer feedback. Step four: Performance verification. After one week of operation, compare evaporation efficiency, condensate turbidity, and equipment inspection cycle data. 

An application case comes from a chemical intermediate manufacturer in East China. The MVR evaporation system treated wastewater containing anionic surfactants, with vacuum maintained at -80 kPa. The original conventional silicone defoamer required manual re-dosing every 2 hours, with foam layer thickness consistently at 10-15 cm, and the heat exchanger needed cleaning every 3 days. After switching to Chemi Tech's specialized defoamer for vacuum evaporation, the foam layer dropped below 3 cm after the first dose, stabilized within 1 cm after 48 hours of operation, dosing intervals extended to 24 hours, and heat exchanger cleaning intervals extended to 14 days. Evaporation efficiency increased by 12% and steam consumption decreased by 8%. 

This solution has been proven effective in vacuum evaporation scenarios including petroleum refining, textile wastewater, and paper-making black liquor concentration. The key lies in matching the system vacuum level with the surfactant structure of the defoamer, rather than blindly increasing dosage. For specific selection parameter tables or optimization recommendations, contact technical support directly for operational advice.