During the operation of wet flue gas desulfurization (FGD) systems, foam problems often become an invisible killer of efficiency. Foam accumulation causes slurry overflow and pump cavitation, sends desulfurization efficiency plummeting and can even bring the system to a halt. Conventional antifoams are either slow to take effect or short-lived; worse still, some products interfere with the contact reaction between the absorbent and sulfur dioxide, wasting chemicals.
Chemi Tech desulfurization antifoam is designed for these pain points, using a composite formulation of specialty polyether and silicone. It spreads quickly on the foam surface and breaks the liquid film tension to achieve defoaming within seconds. At the same time, its molecular structure is stable and does not readily decompose in high-temperature, highly alkaline desulfurization slurry; its foam inhibition time can be more than 3 times longer than that of ordinary antifoams, and it changes neither the slurry pH value nor the desulfurization chemical equilibrium.
Step one: diagnose the degree of foaming. Judge the severity level by observing the foam layer height and slurry overflow. Mild foam (foam layer below 10 cm) can be handled with preventive dripping; moderate foam (10-30 cm) requires periodic metered addition; severe foam (above 30 cm or already overflowing) requires immediate shock dosing combined with continuous dripping.
Step two: determine the method of addition. Continuous dripping with a metering pump at the circulating slurry inlet of the absorber tower or in the foam accumulation zone is recommended, with the dosage set at 0.005%-0.02% of the slurry volume. If on-site conditions do not allow this, intermittent batch addition can be used, but the interval between additions should not exceed 4 hours.
Step three: dynamic monitoring and adjustment. After dosing, record the change in foam layer height every 2 hours. If the foam height drops by more than 50% within 2 hours, maintain the current dosage; if the effect is not significant, gradually increase the dosage by 10% until the foam stabilizes within a controllable range.
Practical case: the FGD tower of a 300 MW unit at a refining and chemical enterprise in East China frequently experienced slurry overflow during operation, with the foam layer reaching 40 cm. The antifoam originally used had to be added once every 4 hours and caused desulfurization efficiency to drop from 98% to 93%. After switching to Chemi Tech desulfurization antifoam, the first shock dose of 0.02% by volume brought the foam layer down to 5 cm within 30 minutes; it then shifted to continuous dripping at 0.008% by volume, and the foam layer stayed below 8 cm for the following 24 hours, with desulfurization efficiency recovering to 97.5% and chemical consumption cost falling by 40%.