Diversification is the keynote of the use of copper and copper alloys in current general engineering practice. With such a wide range of materials available in a variety of forms, such as sheet, strip, wire, extruded sections, etc., engineering designers are continuing to specify the copper metals for applications large and small. A number of uses of copper today are spectacular and impressive, such as the large copper brewing vats, but the majority are in the form of machine or plant components and are usually unobtrusive to the layman.
The vast chemical engineering industry, which affects almost every aspect of daily life, uses copper (or its alloys) as a constructional material because of its high rate of heat transfer, its ease of manipulation and joining and its resistance to certain corrosive acids at normal or moderately high temperatures. The choice of material often depends mainly upon the latter consideration which in turn involves not only the nature of the liquid concerned but also its temperature, concentration, rate of flow, etc. For very exacting conditions 'Monel', a nickel-copper alloy, is often specified.
Copper plate or sheet is ductile and malleable. It can readily be hammered into pans or shaped and riveted, brazed, or welded into tanks, boilers and other containers of all shapes and sizes. Very large thick boiling-pans are also made from aluminium brass. Copper and a wide range of alloys are fabricated into tubes for transporting a variety of liquids and gases, including oil products, and they are also used for heating coils and in evaporators, refrigerators (for which there is a special range of sizes), in shell and tube condensers and for numerous other purposes.
Copper evaporators are used for concentrating sugar, milk, extract of malt, coffee, tannin, and for gelatine, lactic acid, sulphite liquor, etc. The American nuclear power station at Indian Point has a ' giant evaporator, 65 ft long, in which the tube bundles are made of 80/20 cupro-nickel.
Other copper alloys, including silicon bronze and 'Monel', are employed in the evaporation of sea-water, an application which is expected to increase with current expansion in the construction of distillation plant.
Glucose converters, sugar rollers, stirrers, and furnace-pans, vacuum pans, stills, fruit-slicing wheels, cattle-food and poultry mashers, heat exchangers, textile-drying machines, and the rotproofing of textiles for damp tropical climates are among the many miscellaneous items for which copper and copper alloys are used.
Copper distilling columns used in the production of industrial alcohol, fatty acids, essential oils, etc., are of special interest. The great penicillin plant at Speke, near Liverpool, is a specific instance of the use of copper in this respect. The recovery of extracts calls for fractionating columns which are 23 ft high and 5 ft in diameter and are built of deoxidized copper sheets. Each column is in seven sections, six of which have riveted copper bubble plates, and each plate incorporates sixty copper bubblers and uptubes. This makes an interesting comparison with the practice a thousand years ago of the Arabs who distilled essences in gourd-shaped copper vessels.
In the numerous operations involved in the brewing of beer, copper has played a predominant part for many centuries. Copper sheet is very often used for lining the mash tuns and fermenting vessels; and the brewing coppers are almost always made of copper, as indeed their name implies. The world-famous brewery of Guinness's in Dublin has nineteen of these huge coppers, each of which holds 23,400 gallons. The slotted false bottoms of brewery mash tuns are made of bronze or brass. The round or oval coiled tubes called attemperators, through which cold water or brine circulates in the fermenting vessels, are of copper because of its high heat conductivity, and so are the steam coils in the brewing copper and the various distribution pipes. Copper tanks may even carry the beer away.
Figure 59. Whisky stills are invariably made of copper. In the pot-still process the malt whisky is distilled twice and two identical copper stills are used as shown.In scores of other industries, which are loosely classified under general engineering, copper and copper alloys are used for an infinite variety of applications, ranging from small mass-produced parts in free-machining brass to equipment for the 'space-age' industries of rocket production and atomic energy. The giant electromagnets employed in atom-smashers have copper wire windings. A cyclotron at Harwell has 70 tons of copper strip for this purpose, while 'Nimrod', a more recent machine at the same plant, has more than 300 tons of high-conductivity copper bars coiled around its electromagnet. The proton synchrotron at Brookhaven, New York, which is even larger, can accelerate its bombarding particles up to 30,000 million electron-volts. The electromagnet of this huge machine measures 843 ft across and contains about 4,000 tons of iron and 400 tons of copper bars in coils. All these giants have evolved from a small machine built in 1930, One of its most essential parts, the magnetron body, was turned wholly out of high-conductivity copper.