Product Dose

Antifoam Defoamer AF10 can be used to control foaming in all types of seawater distillation plant and is particularly suitable for use in multi-stage flash plants. Antifoam Defoamer AF10 is a formulated product containing ethylene oxide / propylene oxide block copolymer. As such it is not soluble in water but readily forms a stable emulsion at concentrations up to 1% w/w in distillate. Antifoam Defoamer AF10 is typically dosed as a 1% w/w emulsion in distillate prepared as follows:

• Add 50% - 70% of required distillate volume into dosing tank;
• Start the dosing tank agitator/mixer;
• Add the required Antifoam Defoamer AF10 volume into the dosing tank;
• Add the remaining volume of distillate to give the required concentration of Antifoam Defoamer AF10 solution;
• Continue agitation for a further 10 - 15 minutes;
• The resulting emulsion will be stable and will not normally separate

The dose level required will depend on the quality of the seawater feed (e.g. dissolved organics, suspended solids) but is typically found to be in the range 0.05 to 0.1 mg/l and is subject to optimisation as operating experience is gained. Dose level is not dependent on operating temperature of the distillation plant. Recommended injection points are either into the seawater make-up line after any external de-aeration and decarbonation equipment, or into the recycle brine stream at a suitable point after the blowdown and typically into the discharge of the recycle brine pump.

General-purpose antifoams have a wide range of applicability, but not all of them are suitable for use in the treatment. Some foam control agents can aggravate the problem. Foam control in gas scrubbers is only one of the process parameters to be monitored. It is equally important to prevent or slow the fouling of the unit, because dismantling of the gas-scrubbing units is manually intensive. Incorrectly specified antifoams can easily lead to increased fouling and clogging, particularly in the heat exchangers. Momentive Performance Materials RXSOL antifoams are designed to provide foam control with a minimum of such problems.