Dr. Willem A. J. Bogers, presi­dent of DSM's board of directors, says, "The human aspect of the tragedy weighs most heavily with us and this is our prime concern." He adds that nothing will be left undone to establish the cause of the accident. Ironically, only two days before, the Dutch government boil­er inspectors had examined the cracker following the overhaul.

As DSM workers began sorting out the wreckage, other units on the site were being cautiously brought back into production. These include a 350,000 metric-ton-per-year (of ethylene) naphtha cracker and plants for making low-and high-density polyethylene, polypropylene, polyvinyl chloride, acrylonitrile, butadiene, styrene resins, and ethylene-propylene-diene monomer.

Despite the total loss of the smaller cracker and stored naph­tha, DSM management doesn't foresee any major interruption in output of downstream plants. For one thing, these units currently are running well below capacity levels because of slack demand. For an­other, DSM can draw on ethylene from the pipeline grid that connects it with other producers in Belgium, the Netherlands, and West Germa­ny, α

Burning wastes at sea gets EPA okay The Environmental Protection Agency says in a report released last week that ocean incineration of liquid industrial chemical wastes "could be a viable method" that should be considered along with other disposal methods such as ocean dumping, land disposal, and incineration on land. The agency has evaluated and found the "first officially sanctioned" U.S. use of ocean incineration to be "environ­mentally compatible." Although ocean incineration is new to the U.S., it has been in use in Europe for several years.

Between October 1974 and Janu­ary 1975, four batches of chemical wastes—primarily a mixture of tri-chloropropane, trichloroethane, and dichloroethane—from Shell Chemi­cal's Deer Park, Tex., plant were burned aboard the M/T Vulcanus about 241 km from land in the Gulf of Mexico. The ship, owned by Ocean Combustion Services B.V. of the Netherlands, is equipped with two high-temperature incinerators that are designed to oxidize more than 99.9% of organochlorine

M/T Vulcanus: two huge incinerators

wastes. It has operated successfully for two years in Europe, discharg­ing hydrogen chloride, carbon diox­ide, and water directly into the at­mosphere without scrubbing.

A total of 16,800 metric tons of Shell Chemical's wastes were incin­erated at a maximum rate of 25 metric tons per hour with a 1200° C minimum and a 1350° C average flame temperature. EPA, other fed­eral agencies, the Coast Guard, private instrumentation firms, and Shell Chemical monitored the stack gas emissions and plume.

The monitoring efforts proved that more than 99.9% of the wastes were indeed oxidized. Marine mon­itoring indicated that there were no measurable increases in concentra­tions of trace metals and organo-chlorines in the water and marine life. Further, no adverse effects on migratory birds were observed.

Based on the experience gained from the Shell tests, EPA has made recommendations to improve the efficiency of future ocean incinera­tion. The recommendations include changes in the design and operation of the shipboard incinerators, mon­itoring equipment, communication, and navigation. D

New process controls offer flexibility After more than five years of devel­opment, Honeywell's new process control system for the chemical, petrochemical, and related process industries was unveiled last week. Said to be the first complete sys­tem for process control to use mi­croprocessor controllers, Honey­well's system also includes stand­alone cathode ray tube display stations, a data "hiway" for infor­mation transfer, and the capability of connecting into a process com­puter when more sophisticated con­trol is needed.

I Altogether, the company expects its new system, called TDC 2000 for Total Distributed Control, to provide significantly more flexibili­ty of control to most process control operations at costs that will range from about equal to those of analog control systems for smaller plants to as much as 20% less in large-scale operations.

Control flexibility comes in two ways. First, from the basic element of the system, the digital controller. By using microprocessors, the con­troller can be reconfigured on-line to perform any combination of eight control functions from 28 equations. Since configuration changes can be made after equip­ment has been ordered and in­stalled, process control equipment orders for new plants can be placed earlier, hastening plant startup. Even after the plant is in operation, control changes can be implement­ed with very little interruption of production.

More flexibility comes from the modular aspect of the system. "We think that one of the big advan­tages of this advanced electronic architecture is that it is a family of modular products that can be built into various packages to satisfy the requirements of a nearly unlimited range of industrial control applica­tion," says Honeywell board chair­man Stephen F. Keating.

A smaller operation probably would have a battery of digital con­trollers connected to a cathode ray display station where an operator would monitor up to 1400 points of information from a single display screen. A larger plant could com­bine several of these operator sta­tions into a central operations cen­ter by means of the data line. And for those systems that need more sophisticated control than the mi­croprocessors allow, compatible process computers can be added through the same data line.

In addition to the savings that come from shortening plant startup time, Honeywell expects its TDC 2000 system to be less expensive to install and maintain than competi­tive systems because of the simplic­ity of its wiring. The basic data line of the system is a single coaxial cable that carries data at 250,000 bits per second, about 10 times the capacity of a telephone line. Simple plug-in connections make installa­tion very simple and economical, Honeywell says. The company esti­mates that for a $200 million chem­ical plant the TDC system would eliminate miles of wiring and re­duce installation costs by more

I than $1 million. •

8 C&EN Nov. 17, 1975