Industrial waters test exchangers

Experience with tubular heat exchangers in aluminium alloys of the series 3000, 5000 and 6000 used for desalination of seawater has shown that aluminium can withstand a flow speed in the order of 2.5-3 m s at temperatures up to 130 °C with no erosion corrosion. This range corresponds to the usual flow speed in industrial installations. Tests with distilled water at 100 °C have shown that the erosion of aluminium starts at a flow speed in the order of 12-15 m-s [42]. 

Recommended model particle systems are enzymes immobilised on carriers ([27,44,45,47,49]), oil/water/surfactant or solvent/water/surfactant emulsions ([27, 44, 45] or [71, 72]) and a certain clay/polymer floccular system ([27, 42-52]), which have proved suitable in numerous tests. The enzyme resin described in [27,44,47] (acylase immobilised on an ion-exchanger) is used on an industrial scale for the cleavage of Penicillin G and is therefore also a biological material system. In Table 3 are given some data to model particle systems. 

Hydrochloric acid may be purchased or produced internally. It is a widely available commodity, easily obtained in good quality. HCl is available in the anhydrous form as well as in the form of aqueous acid (up to 23° Be or about 37% HCl). The use of aqueous acid is standard in the chlor-alkali industry, and we do not discuss anhydrous HCl here. Byproduct acids are available, sometimes at lower prices, and may be suitable for use in the chlor-alkali process. Their quality should be checked carefully, and testing may be advisable before use. When HCl is produced from chlorine liquefaction tail gas, the absorbing water is the most likely source of impurities. Demineralized water is the standard source when producing acid for use in a membrane-cell chlorine plant. A certain amount of chlorine tends to be present in burner acid. This can be minimized by process control, and a small bed packed with activated carbon (Section 7.5.9.3B) is a useful safeguard. Usually only the acid intended for use in the ion-exchange system need be treated in this way. 

STEAM. H2O. In laboratory tests under static conditions, alloy 3003 was found to be resistant to pure steam over distilled water at temperatures up to 268 C (514°F). In fact, aluminum alloys exposed to steam at these temperatures had improved resistance to corrosion by other environments because of the increased thickness of the oxide film on the surface. In the same tests, steam at 268°C (514°F) was corrosive. High pressure steam can erode aluminum alloys by impingement corrosion erosion, particularly when the jet of steam is perpendicular to the surface. Aluminum alloy equipment including heat exchangers. dryers, steam jacketed kettles, piping have been used to handle steam in the petroleum, chemical and food processing industries. See also Ref (1) p. 144, (2) p. 778, (4) p. 49, (7) p. 175. 

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