Light ends manufacturing

Steam Cracking. Steam cracking is a nonselective process that produces many products from a variety of feedstocks by free-radical reactions. An excellent treatise on the fundamentals of manufacturing ethylene has been given (44). Eeedstocks range from ethane on the light end to heavy vacuum gas oil on the heavy end. All produce the same product slate but in different amounts depending on the feedstock. 

To obtain light ends conversion, alkylation and polymerization are used to increase the relative amounts of liquid fuel products manufactured. Alkylation converts olefins, (propylene, butylenes, amylenes, etc.), into high octane gasoline by reacting them with isobutane. Polymerization involves reaction of propylene and/or butylenes to produce an unsamrated hydrocarbon mixture in the motor gasoline boiling range. 

AppHcations of mercury include use in batteries (qv), chlorine and caustic soda manufacture (see Alkali and chlorine products), pigments (see Pigments, inorganic), light switches, electric lighting, thermostats, dental repair (see Dental materials), and preservative formulations for paints (qv) (1—3). As of the end of the twentieth century, however, increased awareness of and concern for mercury toxicity has resulted in both voluntary and regulatory reduction of mercury usage (see also Mercury compounds). 

Semiconductor laser diodes are widely used in CD players, DVDs, printers, telecommunication or laser pointers. In the structure, they are similar to LEDs but they have a resonant cavity where laser amplification takes place. A Fabry-Perot cavity is established by polishing the end facets of the junction diode (so that they act as mirrors) and also by roughening the side edges to prevent leakage of light from the sides of the device. This structure is known as a homojunction laser and is a very basic one. Contemporary laser diodes are manufactured as double heterojunction structures. 

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