Fouling liquid side

Somerscales, E.F.C., 1988, Corrosion fouling liquid side, in Melo, L.F., Bott, T.R. and Bernardo, C.A. eds. Fouling Science and Technology, Kluwer Academic Publishers, Dordrecht. 

TABLE 17.39 Influence of Operating Variables on Liquid-Side Fouling [2]... 

Prevention and Reduction of Liquid-Side Fouling. Among the most frequently used techniques for reduction of liquid-side fouling is the online utilization of chemical inhibitors/ additives. The list of additives includes (1) dispersants to maintain particles in suspension, (2) various compounds to prevent polymerization and chemical reactions, (3) corrosion inhibitors or passivators to minimize corrosion, (4) chlorine and other biocide/germicides to prevent biofouling, and (5) softeners, acids, and poliphosphates to prevent crystallization. Finally, an efficient mechanical removal of particles can be performed by filtration. An extensive review of fouling control measures is provided in Ret 150. 

If fouling due to chemical reaction is anticipated on the organic liquid side of the tube, operating at the higher velocity would reduce the problem since chemical reactions are temperature sensitive. Furthermore the shear force will be increased by a factor of around 4 which is also likely to reduce the extent of the fouling. In addition, because of the increased overall heat transfer coefficient at the higher liquid velocity, a heat exchanger based on these data would require a smaller heat... 

The temperature difference between the exiting vapor-liquid mixture and the inlet shell-side steam or hot fluid should not exceed 75-82°F, primarily due to fouling problems and possible conversion in the tube to inefficient film boiling in the upper section of the tubes. 

Should the liquid level in the bottom of the tower rise to the reboiler vapor return nozzle, the tower will certainly flood, but the reboiler heat duty will continue. Unfortunately, reboiler shell-side fouling may also lead to tray flooding. This happens because the fouling can cause a pressure-drop buildup on the shell side of the reboiler. 

Membrane filters are made in a wide variety of pore sizes (Fig. 1). The effective pore size for membranes vary, and membranes can be used in reverse osmosis (RO), nanofiltration (NF), ultrafiltration (UF), and microfiltration (MF). RO membranes are widely used in water treatment to remove ionic contaminations from the water. These membranes have an extreme small pore size and, therefore, require excellent pretreatment steps to reduce any fouling or scaling of the membrane, which would reduce the service lifetime. RO membranes are used by extensive pressures on the upstream side of the filter membrane to force the liquids through the pores. 

C-NMR. Table 2 shows C-NMR data [7] for liquid samples from the bottoms of the atmospheric and vacuum towers, and for side streams from and above the most seriously fouled vacuum tower trays. The data show the vacuum bottom to contain 12 % more aromatics than the atmospheric bottom, while the amount of paraffins is 6 % lower. This indicates that the vacuum residue has a greater "solubilizing power" than the atmospheric tower residue, which possibly accounts for the decreased amount of microscopic particulates in the vacuum bottom. In contrast, the side stream from the severely fouled trays contains only 25 % aromatics and 47 % aliphatics, suggesting a relatively low "solubilizing power" for the local reflux. 

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