SEA WATER:
Boost in Capacity A unique approach to desalinating sea water may substantially reduce building and operating costs for commercial desalting plants of the future. Under a $108,000 contract from the Office of Saline Water, Reynolds Metals Co. will add three vertical tube effects (VTE) to its multistage flash (MSF) pilot unit at Wrightsville Beach, X.C. The result of the combination of the two processes, OSW hopes, will be a 2QÇf increase in output of desalted water compared with the output of the MSF unit alone, Reynolds Metals plans to use extruded aluminum tubes for the heattransfer surfaces in the three YTE's. These tubes should cut capital outlay for an otherwise typical commercial-scale plant by 20 r r. In the MSF process, hot brine is subjected to successively lower temperature and pressure stages. At each lower stage, some of the brine vaporizes or flashes, and the steam is condensed and removed. Cool brine remaining in the last stage is rerouted through the system in the opposite direction. The effect is countercurrent heating in one direction and cooling in the other. Much of the heat energy is conserved. In the VTE process, a thin film of brine falling over a hot, fluted tube produces steam. Because the process takes advantage of increased surface area in the vaporization chamber, heat-transfer coefficients are higher than for MSF systems. The drawback is that there is no convenient way to preheat the brine. In what it hopes will be a happy marriage of the two processes, Reynolds will insert VTE's between units 6, 10, and 12 of its MSF facility. Each 5-foot-high stack will consist of 13 aluminum tubes. Hot brine from one stage of the MSF will be pumped
Desalination plant Marriage of two systems 10 C&EN JAN. 19, 1970
into the stack for distillation. Concentrated brine will be returned to the unit from which it came, Product water will be taken from the MSF train and from the VTE's. Reynolds, which expects plant construction to be completed in June, says that the VTE's will boost output of its pilot unit from 50,000 to 60,000 gallons of desalted water per day. Reynolds and Aqua-Chem built the MSF unit to demonstrate the utility of aluminum-steel construction. "We can live with a steel and aluminum plant," says Reynolds project director D, A. Fauth, "if we can get the steel out of the condenser." Steel shells around the condenser tubes will be replaced by aluminum to eliminate galvanic corrosion.
SYNTHETIC TURF:
Monsanto Challenged If you're a pessimist you can look at synthetic playing turf from the dark side (3M's early troubles with its Tartan Turfs getting progressively darker with use); from the legal side (American Biltrite and World Carpets, Inc., have both been sued by Monsanto for patent infringement); or from the professional football player's perspective (though synthetic turf apparently results in fewer knee and ankle injuries, in the case of Monsanto's Astroturf it is reputed to contribute to skin abrasions). Despite these snarls, however, the artificial grass business continues to grow, both on playing fields and for nonathletic uses, Monsanto, for example, recently announced the startup of its third production unit to make its line of landscaping and decorative surfaces which the company markets under the name AstroGrass, American Biltrite is also planning to enter the decorative grass area (grass for median strips, patios, show windows, and other landscaping uses). The Boston-based company already markets an athletic playing surface, which has been installed at Wichita State University and is currently being put in at Idaho State and the University of Rochester. Both American Biltrite and World Carpets—which has sold its "grass" only for tennis court and golf course use up till now—are embroiled with Monsanto in the legal hassle over the rights to the basic technology involved in making their respective products. American Biltrite has countersued, claiming that Monsanto's patent is invalid. St. Louis-based Monsanto's Astroturf—far and away the leader in playing field installations with about 35 installations to date—is a nylon fila-
Synthetic grass use grows Beyond the football field
ment, while American Biltrite has opted for polypropylene and World Carpets for a 50-50 mix of polypropylene and saran. Although the similarity of the product technologically and the question of who owns rights to it will have to be settled by the courts, all three turfs are layered products whose top stratum is composed of a grasslike pile. 3M's Tartan Turf—which has been installed or is being installed in a total of eight locations—is not based on monofilament technology, a difference that has not only kept 3M out of the legal scrap but has also brought praise from some athletes. Violent encounters with Tartan Turf, they say, are less likely to result in skin burns. Tartan Turf—which until recently had been used only on football fieldswill crack the barrier into major league baseball next year when Pittsburgh's new Three Rivers Stadium is opened for use by the Pirates.
CIRCUITS:
Totally New System A "totally new system" for producing printed circuit boards has been developed by Richardson Co. The new system includes new resins, board materials, and an additive circuit depositing process. The system saves up to 80c/c in both materials cost and processing time compared with conventional processes, Richardson claims. The process uses laminated paper and glass boards based on the firm's RICON resin-a modified 1,2 vinyl polybutadiene polymer which is crosslinked with vinyl toluene. The resin is superior to epoxy, polyester, polycarbonates, polyethylene, and silicone for electrical stability over a wide range of frequencies, temperatures, and humidity conditions, says Max Mansfield, vice president of Richard-
