Fouling monitoring

Corrosion measurement is also undertaken through the use of various designs of corrosion/fouling monitors that simulate heat exchangers. These monitors vary from simple units to sophisticated items of equipment with computerized data management systems. Most monitors are really designed for fouling measurement, and their ability to provide useful corrosion rate data is often limited. 

Practically all of the deposit/fouling monitors discussed so far are suitable for some degree of measurement or evaluation of biomass/biofilm activity. There are also other devices available, for example, a head-loss monitor. This device is simply a 6-ft-long stainless steel tube, through which cooling... 

Bridger Scientific Inc. DATS Fouling Monitor System. Promotional literature, Bridger Scientific, USA. 

Zuniga, Patricia O. Miller, Kenneth Winters, Michael. A Cooling Water Fouling Monitor Senses Upsets, Evaluates Changes. Reprinted from Chemical Processing, April 1990. 

Fryer and Pritchard [1989] emphasise the need to monitor fouling in a food process stream in order that the optimum time for cleaning may be determined so that for instance, a soft otherwise easy to remove deposit, is not converted to a hard intractable form by the action of heat. These authors describe two possible fouling monitors that may be used in a "side stream" fi-om the main process stream. A more detailed discussion of fouling monitors is to be found in Chapter 17. 

Fryer, P.J. and Pritchard, A.M., 1989, A comparison of two possible fouling monitors for the food processing industry, in Field, R.W. and Howell, J.A. eds. Process Engineering in the Food Industry. Elsevier Applied Science, London. 

Because of the widespread use of cooling water and the need to assess treatment programmes, monitors have been developed specifically for use in cooling water systems. Many of these devices are relatively simple and do not necessarily require the use of a mobile laboratory. Moore and Hays [1985] produced a survey of commercial fouling monitors that could be used in conjunction with cooling water and EPRI [1985] made a status survey of 18 biofouling detection monitoring devices. Chenoweth [1988] provides detailed information on ten such monitors. He observes that the choice of monitor depends on a number of questions, the answers to which will not only affect the cost but also the quality of the data obtained. 

Chenoweth, J.M., 1988, Liquid fouling monitoring equipment, in Melo, L.F., Bott, T.R. and Bernardo, C.A. Fouling - Science and Technology. Kluwer Academic Publishers, Dordrecht, 49-65. 

Moore, W.E. and Hays, G.F., 1985, Guidelines for selection and use of on-line fouling monitors. Paper TP-85-2 Cooling Tower Inst. Annual Meeting. 

Winters, M., Stokes, P., Zuniga, P., and Schlottenhier, D., "Developments in On-Line Corrosion and Fouling Monitoring in Cooling Water Systems, Paper No. 392, Coi-rosion/93, NACE International. 

Table 3 Commercial fouling monitors and biofilm sampling devices...

Betz Biofilm Fouling Monitor (coupon collection) ... 

Dats Fouling Monitor from Bridger Scientific (heat transfer resistance) ... 

Sessile bacteria are measured either by analysing deposits taken from the machine, or by using a fouling monitor, or following the rate and nature of deposition on a reference surface in the machine using either a microscope to see individual sessile cells of enumerating some of the microbes present by plating the actual deposit. 

Model of biofilm growth. Although some people use the paper machine as a fouling monitor for sessile growth, it is not recommended ... 

In parallel to lab experiences, optical fouling monitors and coupons (removed at 14 days intervals and analysed for colony forming units of aerobic bacteria and sulphate-reducing anaerobic bacteria) have been used to monitor and measure biofilm formation on machines. 

Figure 15 Optical fouling monitor general description.

Towards Fouling Monitoring and Visualization in Membrane Bioreactors... 

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