EQUIPMENT
T h e company now produces plastic bubble caps and risers in sizes u p to 8 in. o.d. They are not shelf items, b u t are custom made, says Robert L. Jarmon, Wyatt's sales manager. Molding, he adds, makes it possible for t h e d e sign engineer to get exactly what h e needs for his process without excessive ma^hinin* 7 ^osts
Computer Snubs Weather Phillips develops system to eliminate température effects on column operation Jr HILLIPS Petroleum has developed
PLASTIC BUBBLE CAPS AND RISERS. A workman at Wyatt's Plastics assembles a bubble cap (left) and riser made from a thermosetting plastic. High corrosion resistance and low molding cost are t h e big selling points of t h e unit
sties Invade Tower Equipment Low cost, high tensile strength, a n d corrosion resistance m a k e plastics attractive for bubble caps a n d risers JL IIERMOSETTING plastics are gaining a
toehold as a building material for distillation a n d treating towers. And if preliminary tests mean anything, they may soon offer strong competition to pressed carbon a n d even metals in uses where corrosion resistance is important. Wyatt's Plastics, Houston, Tex., unveiled its new products—thermosetting plastic bubble caps and risers—at the World Petroleum Congress this week in New York. Later, the company plans to include plastic trays, downcomers, and other distillation and treating tower assemblies in its line. Wyatt's says its new material, called Wyatt's 1099, is a thermosetting plastic, but declines to say more about its composition. T h e company claims, though, that it meets most of the corrosion resistance requirements found in t h e refining 58
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a n a cnemicai processing uiuustnes. The bubble caps and risers were tested in "one of the world's largest refineries." After one year in a tower contacting 55 to 65',r sulfuric acid at 340° F., t h e parts showed no corrosion or other ill effects. L a b tests also indicate that they are resistant to a host of other chemicals. • Low Cost. Wyatt's thinks that bubble caps and risers made from its plastic will cost less than those made from competing materials. This is b e cause they can b e molded, while other materials require machining. Its tensile strength (about 5000 p.s.i.) is greater than that of pressed carbon. Thus, openings in the risers can b e made larger without weakening them. This means greater throughputs a n d , hence, greater economy, says Wyatt's.
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computer control system to eliminate the effects of ambient temperature on reflux which has been condensed a n d cooled with air-fan coolers. Also, t h e system gives savings in reboiler steam and maintenance costs. Without this new system, even small changes in ambient temperature, such as that caused by a cloud blocking o u t the sun over an air-fan cooler, will upset fractionator column operation seriously. Basic work in developing a computer control system came through efforts of Phillips Petroleum's research and d e velopment department. Phillips' operating departments wanted better products from fractionators at lower costs. A n d they also insisted upon consistent quality of sepai ation, says Phillips' Dale E. Lupfer. Lupfer is one of a group that thought the answer to improved column stability should come through control of internal reflux flow rate rather than through external reflux temperature. Conventional control of reflux temperature is slow a n d unsatisfactory when disturbed b y changing ambient conditions. The result: Column performance changed before temperature control could compensate. While internal reflux computers are used mostly on fractionators equipped with air-fan coolers, almost one third of the computers used b y Phillips are on columns that use water-cooled condensers. Here, Lupfer says, the problem is more operating economics than operating stability. Any fractionator that consistently requires more heat for night operation could use internal reflux control. • Why Internal Control. Air-fan condensing systems which are controlled by temperature of reflux have
