Fouling indicators

Reiss C.R., Taylor J.S. (1995), Prediction of nanofiltet productivity decline using fouling indices, Proc. AWWA Membrane Technology Conf., Reno, Nevada, Aug 95, 433-448. 

Examination of fouling indices aaoss the entire collection yidded intaesting structure-activity rdationships (Figure 30). At least one monomer from each of eight categories performed betta than the unmodified control, with only membranes... 

Figure 30 (a) Fouling indices for different monomer classes. The number of monomers in each class with a specific fouling Index Is shown, (b) Ranking of modified surfaces relative to PES for resistance to natural organic matter (NOM) fouling. Adapted from Zhou, M. Y. Liu, H. W. Kilduff, J. E. etal. Environ. Sci. Technol. 2009, 43 (10), 3865-3871, and reprinted with permission from the American Chemical Society. 

Moon, J. Lee, S., Song, J.H., and Cho, J. (2010). Membrane fouling indicator of effluent organic matter with nanoflltration for wastewater reclamation, as obtained from flow field-flow fractionation. Sep. Purif. TechnoL, 73(2) 164-172. 

Circffiation and heat transfer in this type of evaporator are strongly affected by the liquid level. Highest heat-transfer coefficients are achieved when the level, as indicated by an external gauge glass, is only about halfway up the tubes. Shght reductions in level below the optimum result in incomplete wetting of the tube walls with a consequent increased tendency to foul and a rapid reduction in capacity. When this type of evaporator is used with a liquid that can deposit salt or scale, it is customary to operate with the liquid level appreciably higher than the optimum and usually appreciably above the top tube sheet. 

A test water box was installed during a 2-week trial to monitor corrosion and fouling in a utility cooling water system. A baffle plate from the test box was removed after the test. Small, hollow incipient tubercles dotted surfaces (Fig. 3.28). Small amounts of carbonate were present atop and around each tubercle. Each tubercle capped a small depression no deeper than 0.005 in. (0.013 cm) (Fig. 3.29). This indicated local average corrosion rates were as high as 130 mihy (3.3 mm/y). 

The above analysis indicates that the high concentrations of sulfur-containing deposits and corrosion products were caused by the influence of large organisms. Bacterial contributions to corrosion and associated fouling were minimal. 

The pour point is an indication of the lowest temperature at which a fuel oil can be stored and still be capable of flowing under gravitational forces. Fuels with higher pour points are permissible where the piping has been heated. Water and sediment in the fuel lead to fouling of the fuel system and obstruction in fuel filters. 

Distributor full of scale. Poor separation. Some scans indicated liquid maldistribution. Fouling. 

The overall temperature difference is 10-18°F, depending on fouling. Vacuum operation on the steam side is indicated. 

Check the recirculating CW pressure. An increase in pressure drop indicates fouled or plugged tubes, or a fouled tube sheet. 

Several cleaning methods are used to remove the densified gel layer of retained material from the membrane surface. Alkaline solutions followed by hot detergent solutions are indicated for organic polymer colloids and gelatinous materials fouling. Ferrous deposits, t3 pical in water treatments, are usually removed with a citric or hydrochloric wash. [35]. 

---