Heat exchangers biofouling

Corrosion. Copper and selected copper aHoys perform admirably in many hostile environments. Copper aHoys with the appropriate corrosion resistance characteristics are recommended for atmospheric exposure (architectural and builder s hardware), for use in fresh water supply (plumbing lines and fittings), in marine appHcations (desalination equipment and biofouling avoidance), for industrial and chemical plant equipment (heat exchangers and condensers), and for electrical/electronic appHcations (coimectors and semiconductor package lead-frames) (30) (see Packaging). 

Any of a number of items of equipment used to determine the rate of deposition of biofoulants, scale formation or corrosion debris, in laboratory studies of new products, or in actual field use. Typically using a heated tube to simulate actual heat-exchanger conditions. 

Dohnal, M. and Bott, T.R., 1995, Application of fuzzy logic to heat exchanger fouling with special reference to biofouling. To be published. 

The simplest method for assessing the extent of deposition on test surfaces in the laboratory is by direct weighing. The method requires an accurate balance so that relatively small changes in deposit mass may be detected. It may be necessary to use thin walled tube to reduce the tare mass so as to increase the accuracy of the method. Mott and Bott [1991] used the technique satisfactorily, to estimate the amount of biofouling that had accumulated on the inside of simulated heat exchanger tubes. The mean thickness of the biofilm over the whole inner surface of the tube may be made from a knowledge of the deposit density for biofilms the density may be assumed to be that of water since the biofilm is substantially made up of water [Patel 1981]. The inside surface area of the tube is given by... 

R. Mitchell and P. Benson, Control of Marine Biofouling in Heat Exchanger Systems, MTSJ. 15(4), 11-21 (1981). 

Marine applications involving supply lines, heat exchangers, and hardware where resistance to seawater and biofouling are mandatory. 

The PCHE was chosen because space constraints were critical (see Figure 9.2) and the above ground location favoured the 1 tonne PCHE rather than the 20 tonne equivalent shell and tube exchanger. Prior to installation, a series of trials on the prevention of biofouling in narrow channel heat exchangers carried out at another BP Amoco terminal showed that control by chemical injection was acceptable in the titanium PCHE (Anon, 1998 Reay, 1999). 

PDM-1 Deposition Monitor from Yost and Son Inc. (heat transfer resistance) Cortest Heat Exchanger System from Cortest (pressure drop and heat transfer) Nalco Delta-T Biofouling Monitor (Pressure drop measurement) ... 

Copper and its alloys are widely used for fresh and sea water heat-exchanger applications, because they are especially resistant to biofouling. 

Coastal power and process industry plants have used chlorine to control biofouling and shme formation for many years. Chlorine injection is normally provided for heat exchangers in coastal plants that are seldom cleaned more than once a year and for naval ships that must maintain their equipment at maximum efficiency at all times. Chlorine may be added in the gaseous form or developed in situ via electrolytic chlorine generation. 

Lewis R.O., Influence of biofouling countermeasures on corrosion of heat exchangers materials in sea water, Materials Performance, vol. 21, 1982, p. 31-38. 

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