EARL L. WALLS
SYMPOSIUM ON FINE CHEMICALS PLANTS
ilding How Did Fare?
ifteen years ago, Monsanto Co. set out to plan and
F construct an engineering research laboratory at Nitro, W. Va., in which the company would attempt to
“further the engineering study of chemical processes and to provide a laboratory for the pursuit and advancement of chemical engineering technology.’’ For its time, the building involved a variety of design innovations (within Monsanto, at least) and resulted in modifications of existing designs and operating procedures for the company. Now that the facility has reached the end of its usefulness from the Monsanto master plan point of view-the company has razed the structure to meet other needs-it is appropriate to evaluate these innovations to determine the good, the bad, and the indifferent. Before design commenced, certain basic parameters were established. Generally, these included economical construction and operation, as well as technological
Earl L. Walls is founder of the Earl L. Walls Associates, Design Consultants, 7460 La Jolla Blvd., La Jolla, Calif. 92037. This fiaper was presented as part of the Symposium on Fine Chemicals Plants, 158th National ACS Meeting, New York, N. Y., September 7-12, 1969. Photographs are courtesy of Monsanto Chemical Co. AUTHOR
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Figure l a , b , c, d.
Floor plans at variousjloor levels
adaptability. The design thinking could be broken into two basic groups-idcas involving the structure and those involving the operation. Economy in construction and maximum adaptability of space obviously could be achieved best with a structure built of essentially similar building blocks. I t would simplify the ordering of construction materials and make one space in the building the same as almost any other. T h e building block selected was a basic building module. For the Monsanto needs, a basic 20 ft2 bay size, working in a 12-ft floor-to-floor height best met the function criteria (Figures la, b, c, d). The presumption was that all the envisioned processes could be performed within such a volume, and experience proved this out. The modular approach to planning and construction is, of course, quite commonplace today. Once the building module was resolved, attention to materials and details could follow. The building interior would be essentially open, with the framing system exposed. Cost factors dictated a steel frame structure, but the heavy chemical environment posed problems. The solution was to galvanize the structural steel (Figure 2 ) . This offered both benefits and problems. The problem came during erection of the steel. The galvanizing process, which followed welding, resulted in warping of the steel members. While it made erection more difficult, the long-range benefits offset this difficulty. I n the 15 years of operation, no corrosion of the steel frame was de44
INDUSTRIAL A N D ENGINEERING CHEMISTRY
Figure 2. Structural steel galvanized before use
Figure 3. Overall building appearance with galvanized metal
Figure 4. Nonslil, waxedjooring withstood years of operation
tected, and the maintenance costs attributed to the building frame were minimal, such that, in the long run, the galvanized structural system was a plus. Again, with cost in mind, the exterior of the building was clad in corrugated aluminum sheets of 61s alloy. Flashing, gravel stops and facias, roof and floor thimbles, and similar details were fabricated from either 54s or 61 S aluminum alloy. There were admitted reservations about the use of aluminum in this sort of environment, with constant chemical fumes exposure. However, the belief that the aluminum would form its own protection by oxidation proved correct, and the potential corrosion problem did not arise. Though discolored, which consequently detracted from the building’s appearance, the metal stood up well and would be rated successful (Figure 3). Windows in the pilot plant facility proved more of a problem. Windows are a significant maintenance factor in any chemical plant building because of washing and breakage. With a n eye toward reducing this maintenance factor and to give a boost to the use of plastic as a construction material, we selected glass cloth-reinforced panels of polyester resins. During the life of the facility these windows, which were green, faded badly, resulting in a loss of attractiveness. However, recent advances in coloring polyesters may alleviate this problem. Floors are usually the least practical way to achieve adaptability in a facility. We early decided we would seek to reach our goal by other systems, and this permitted us to consider concrete for the floors. Acid-brick troughs were used in the building, but cost alone prohibited using this material as the general flooring. Still a hard, smooth, nonslip floor surface was needed, resistant to acid and caustics, which could provide nonsparking static conduction. The resolution of this problem was the introduction of a n additive containing iron filings into the topping slab. The only maintenance of this floor through the years of operation was periodic waxing, with a colored nonslip wax, and the floor proved successful for its purpose (Figure 4). The choice of ductwork material for chemical usage is always a difficult task. Some materials which solve one problem often create others. For this facility, we selected a coated steel duct. This particular duct material
(Galbestos) has asbestos felt bonded to the steel core during the galvanizing process, which immediately afterward undergoes asphaltic impregnation. Other coatings are also applied. The result was no duct failures. I n fact, this duct material, though difficult to fieldwork, is so successful in performance, that this author continues to recommend it in both industrial and educational facilities in which heavy chemical fuming is contemplated. As operations change within a building, particularly one in which ventilation and exhaust are among the major systems, unplanned roof penetrations can become costly if they require the use of a n outside roofing contractor because of a bonded roof. We knew that such penetrations would occur, but it was not feasible to plan for them specifically. We did want to eliminate the need to call in a contractor each time a change was required. T h e result was the design of a n aluminum roof scuttle with a removable insulated aluminum top through which mechanics could run vent pipes and provide the flashing to accommodate changing equipment layouts. This system also proved to be satisfactory as planned (Figure 5). Two sewer systems were required in the Nitro plant. The service sewer was constructed of cast iron and performed as expected without problem. T h e process sewer was fabricated of glass-reinforced plastic sewer pipe. This proved satisfactory, though the cold West
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Figure 5. Design of aluminum roof scuttle VOL. 6 2 NO. 1
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-Virginia winter created difficulties in joining the piping which required a wrapping and wiping process. Borosilicate glass piping was chosen for the vacuum system. T h e major factor was protection against corrosion, where even pinhole failures would cause serious problems. An added benefit was easy visual inspection of the system. T h e glass system performed as anticipated (Figure 6). Available power of the right type a t the right place is always a pilot plant essential. At the same time, the system provided must be safeguarded both for employees and equipment. The permanently installed equipment could be directly wired. All other power was supplied by means of plugs and receptacles. Single-phase (110 V) and 440-V motors (sometimes as many as five) on a single circuit, all frequently used apparatus, such as reactors, were provided with circuit breaker-starter combinations. The procedure was to plug the circuit breaker into the system; then the starter into the circuit breaker. As a protection, the starter plugs would not fit into the circuit breaker. As a protection, the starter plugs would not fit into the system-only into the circuit breakers. I t had the added advantage of bringing the circuit breaker close to the operation. Overall, the system worked well during the life of the Nitro facility and is a solution we have applied elsewhere in pilot plant operations (Figure 7). The establishment of the modular bays implied the movement of major equipment from one space to another and, hopefully, with relative ease. The reactors would be the major moving problem. The decision was made to mount the reactors on 4-ftzframes constructed of 1-3/4in. by 3-in. aluminum box channels, with aluminum
tread plate fixed to the top of the channel frames. T h e idea was to use specially designed pickup hook assemblies to fasten to each corner of the deck assembly and lift the reactor by overhead crane. The trick of balancing the reactors proved difficult, even with attempts a t counterbalancing. I n the long run, the best solution was to lift the reactor itself. With this procedure change, movement was quite easy. I n retrospect, redesign of the pickup system would be in order if direct pickup of the reactor is to be avoided (Figure 8). An adaptable facility would be defeated if special piping systems were designed for each reactor or other apparatus. The solution, which worked, was the design of a manifold system which brought all service facilities to
Figure 6. Borosilicate glass piping for uacuum system
Figure 8. Reactors mounted on aluminum box channels for ease of lifting
Figure 7. Circuit-breaker starter combinationsfor electricalpomer
two points on the reactors-jacket inlet and jacket outlet. I n essence, the manifold system consisted of two sections controlled through a three-way valve with lines to the reactor concection points. Controlled in the manifold were brine and brine return, steam and condensate, and water and air. Supply and return were accomplished in either the upper or service risers; connections were provided to supply any of the services in the manifold directly to the process vessels and other equipment or through the automatic controls (Figure 9). The automatic controls were provided to make it possible for the engineering research group to provide more reliable information on consumption rates, flow, temperatures, pressures, and other similar data to the engineering design group. T h e cost of providing enough meters completely to monitor the facility was prohibitive. Therefore, a minimum number of meters was acquired, and the system was designed to insert meters when and where required. When a meter was removed from one manifold to be inserted in another, a spool piece was inserted as a replacement. Electric meters and temperature and pressure instruments were mounted on three-wheeled racks for movement through the facility to the appropriate locations. T h e concept of the portable instrument racks was good, but the particular design evolved for the Nitro installation had shortcomings in top heaviness. This would be one item which would definitely require further design study (Figure 10). With a modular facility, with power and services distributed through the building in a systematic way, the
Figure 9. Design of manifold system
final consideration was to make the equipment as adaptable as the facility. Basically, this was solved by making the equipment as mobile as possible, either by fixing wheels to the apparatus itself or by mounting it on trucks, and by standardizing connections and connection locations. Thus, while the Mikro pulverizer would most normally be used in the drying room, it could be towed to any location when required. I t was outfitted with complete electrical switchgear and could be plugged into the power system. Similarly, pumps were truck-mounted and equipped with manual starters which would plug into circuit breakers wherever the new location happened to be. While the Nitro engineering research laboratory for Monsanto is now history, it provided opportunities to try out approaches to industrial, as well as educational laboratory design and operation procedures which have had and will have application for years to come. Materials, apparatus, and technology will change ; however, the modular building concepts and the involvement of systems engineering in design, first tried for Monsanto on a large scale in this plant, will continue to be the sound approaches to laboratory building design and construc tion. T h e dedicatory plaque on the Nitro building reads, “To further the engineering study of chemical processes and to provide a laboratory for the pursuit and advancement of chemical engineering technology.” This was the goal, and essentially, this was the result. T h e idea building-how did it fare? All things considered, it fared well.
Figure 70. Three-wheeled portable instrument racks
