Feed systems foaming

Features of the ITT Application Process. The high speed FFT Process can be characterized by consideration of the key features of the feed liquor, foam and applicator system employed in the process. 

If thin films are formed in a system (NaDoS and NaDoBS in the absence of electrolyte, or lysozyme, that is not in its isoelectric point) the lower concentration limit cannot be distinguished unambiguously. In these systems the minimum concentration is found from the particular conditions under which the process is conducted (rate of gas feed, dispersity, foam height in the column, etc.) and the limit is no clearly expressed. 

The solvent normally is added to the distillation column above the feed point, while above the solvent feed point is a wash bed to which some of the liquid distillate is returned as reflux. This arrangement prevents any solvent vapor being carried overhead from the column, which would represent a solvent loss from the system as well as contamination of the distillate product. The solvent feed distributor may require special design if the mixture of reflux and solvent feed either foams or flashes. 

Currently, site-specific tests are often conducted to estimate the consumption and effects of additives (Moser and Owens, 1991). Some significant major process variables to examine when considering use of an additive are additive concentration, pH of the absorber feed slurry, and dissolved calcium concentration (Moser et al., 1990). Other important factors to consider in additive use are pH meter maintenance and opmtion, thickener operation, absorber and mist eliminator plugging, foaming (caused by soap-like impurities) in the recirculation tanks, system water balance, and corrosion of the additive feed system (Babcock Wilcox, 1992B). 

Activities associated with bioreactors include gas/hquid contacting, on-hne sensing of concentrations, mixing, heat transfer, foam control, and feed of nutrients or reagents such as those for pH control. The workhorse of the fermentation industry is the conventional batch fermenter shown in Fig. 24-3. Not shown are ladder rungs inside the vessel, antifoam probe, antifoam system, and sensors (pH, dissolved oxygen, temperature, and the like). Note that coils may lie between baffles and the tank wall or connect to the top to minimize openings... 

One Ninian stabilization train was commissioned to prove the plant and to provide gas for power and steam generation. Very early in the commissioning operation, however, severe foaming occurred in the second-stage (low-pressure LP ) gas/oil separator, which operated at 0 7 bar gauge [10 Ibf/sq in ], when the temperature of the initial dead-crude feed was raised to 9I4°F ]490°C. As a result, large quantities of crude were carried into ihe flare relief system. 

Permanent gamma ray scanning equipment was installed on each separator along with foam density and level recorders in the process control room. An emergency trip system that automatically shuts a valve in the appropriate separator gas line to isolate the separator from the compressor suction drums when a high foam level occurs was added also. A similar trip system was insulted in the gas feed line from the HP separator to the power station... 

Tonkovich et al. [123] claimed a 90% size reduction due to the introduction of micro channel systems into their device, which made use of the hydrogen off-gas of the fuel cell anode burnt in monoliths at palladium catalyst to deliver the energy for the fuel evaporation. A metallic nickel foam 0.63 cm high was etched and impregnated with palladium to act as a reactor for the anode effluent It was attached to a micro structured device consisting of liquid feed supply channels and outlet channels for the vapor, the latter flowing counter-flow to the anode effluent... 

In the batch adsorptive bubble separation processes, a feed solution was introduced to a bubble separation column (or chamber) containing an aqueous solution of surface-active materials. Surface-active solutes or complexes that are hydrophobic and readily attachable to the air bubbles are carried up to the surface of the water by the bubbles. The enriched material at the top (whether collapsed foam from a foam separation column or overflow liquid from a nonfoaming bubble separation column) and the clarified drain solution at the bottom are withdrawn from the system. The overall material balance for the process is as follows ... 

For the cells of stripping mode (Fig. 6A), feed is introduced into the system some distance above the liquid pool. It tends to replace the rising interstitial liquid of pool concentration with downcoming liquid of feed concentration. Therefore, the foam leaving the liquid surface is in equilibrium with the feed solution. L, in Eq. (14), should be replaced with L.. The results of the countercurrent stripping action are... 

Require backup systems to monitor flame and provide pilot burning. Care needed not to feed foams or liquids into the flare stack. Because of maintenance of flare tip on elevated flares (and even some open ground and enclosed ground flares), crane or helicopter required possibly for access. Connection often needed for backup flare system, i.e., portable trailer flare or other temporary flare. 

Dissolved solids often enter with the column feed. As the component that retains the solids in solution is evaporated up or down the column, the dissolved solids may be precipitated out of solution, causing plugging. The problem is most common in aqueous distillation systems where the water contains dissolved solids. Incidents where dissolved solids precipitated in columns and caused plugging were described (71, 98, 236, 237, 239). In another incident (107), pr ecipitation caused foaming. In one nitro-service incident (96), precipitation led to a detonation. 

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