Condensation methods, foam production

Foam spray dryiag coasists of forcing gas, usuaHy air or nitrogea, iato the product stream at 1.38 MPa (200 psi) ahead of the pump ia the normal spray dryer circuit. This method improves some of the characteristics of dried milk, such as dispersibHity, bulk deasity, and uniformity. The foam—spray dryer can accept a condensed product with 60% total soHds, as compared to 50% without the foam process. The usual neutralization of acid whey is avoided with the foam—spray dryer (see Drying Foams Sprays). 

Hash devolatilization is a simple and effective method to remove the majority of solvent and unreacted monomers from the polymer solution. Product from the reactor is charged to a flash vessel and throttled to vacuum conditions whereby the volatile solvent and monomers are recovered and condensed. In the process, the polymer melt cools, sometimes considerably, due to the evaporation of volatiles. The polymer product is pumped from the bottom of the flash vessel with a gear pump or other suitable pump for viscous materials. Critical to operation of the flash devolatilization unit is prevention of air back into the unit that reduces stripping ability and potentially allows oxygen into the unit that can discolor products or pose a safety hazard if low autoignition temperature solvents are used. Often one flash devolatilization unit is insufficient to reduce the residual material to a sufficient level and thus additional units can be added in series [61]. In each vessel, the equilibrium concentration of volatile material in the polymer melt, is a function of the pressure and temperature the flash unit operates at, with consideration for the polymer solvent interaction effects described by the Hory-Huggins equation. Flash devolatilization units, while simple to operate, may be prone to foam development as the superheated volatiles rapidly escape from the polymer melt. Viscous polymers or polymers with mixed functionalities... 

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