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Minnesota Mining and Manufacturing
Co., St.
Paul, Minn.
Pilot Plant Building for Small-Scale Operations For more than 2 years, the performance of this installation for engineering research and-process development has been excellent
IN
THIS COMPANY, the pilot plant group must handle assignments ranging from preparing chemicals in small lots to designing complicated chemical processes. T o deal with such heterogeneous problems, a new building was constructed about 2 years ago. Responsibility for providing the building and dealing with the architectural ' firm was assumed by the staff laboratory engineering department. A member of the pilot plant department determined space and service requirements, acted as spokesman for his group, and worked closely with the engineering department during both design and construction. A three-man team, composed of pilot plant and staff engineering personnel, visited chemical pilot plants of several other leading companies and talked with both operating and design engineers. I n this way, much useful information was gathered, which was incorporated into the over-all plan. A site was chosen on the 260-acre researchcenter in St. Paul, which was about '/z mile from the central research laboratory building. This location is somewhat isolated, and yet other laboratory groups, the analytical department, cafeteria, and library are within easy reach. The floor plan finally selected consists of a divided three-story, modified regional laboratory pilot plant area and a single-story laboratory wing. The service areas are consolidated and conveniently close to process areas. Laboratories and offices are grouped at the front of the building with dirrct routes
The Floor Space Is Allocated Thus S q . Ft. % Laboratory and office Nonhazardous process area Hazardous process area Service areas and corridors Storage area (future hazardous process area)
2820 12.1 2360 10.2 5115 2 2 . 0 8500 36.6 4420
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to the operating areas. The over-all layout provides maximum operating efficiency as well as a well-groomed appearance during operation. An additional 4500 square feet of process area can be obtained by decking in open bays of the operating areas. Operation
The pilot plant department, which operates on the theory that process information should be gathered on the smallest practical scale, is divided into two operating sections-process development and chemical engineering research. The process development section scales up and improves laboratory processes. For evaluation studies, 5 to 25 pounds of new material is usually required, and the first step duplicates the chemist's batchwise procedure. Later however, when basic process data for larger facilities are gathered, process improvement and actual preparation of material becomes equally important. Sample lots rarely exceed 100 pounds and with one exception, permanently installed reactors have a capacity of 20 gallons or less. When larger quantities of materials such as fluorochemical intermediates, latices, condensation polymers, or fine chemicals are required, preparation is normally transferred to a semiworks group where the reactions can be carried out in existing batchwise equipment. The chemical engineering research section studies the more basic engineering problems on a bench scale. Projects may or may not originate within this group, but typical assignments include studies in catalysis, kinetics, or evaluation of new reactions and separation techniques. The staff of the pilot plant department, about 30 people, consists of 13 engineers, two chemists, and 15 nontechnical assistants. However, personnel varies
with the work load, and turnover is rather high through transfer to other projects. laboratory and Office Areas
The single story laboratory wing is built on a modular plan with each module measuring 12 by 26 feet. Laboratories, offices, conference room, nonhazardous operational area, and service areas are partitioned by 4-inch cinder blocks. The roof is of precast reinforced concrete slabs, 2 by 8 feet, with a standard a3phalt-sealed exterior. The hallway and offices are covered with asphalt tile, but the laboratories are provided with solvent-resistant rubber tile. Suspended false ceilings are provided in the hallways and offices only. Each single module is designed for one technical man and his assistants. Desk space for the technical man, in a glasspartitioned area adjacent to the outside wall, affords both some protection from laboratory hazards and some degree of privacy. Multiple offices have been generally avoided, and private offices are provided for supervisors only. One single module is used as a combination of conference and lunchroom, but services are available to convert this room to a standard laboratory. Three double modules are equipped for bench-scale engineering studies. An 8-foot high-capacity fume hood and a 10foot chemical bench are installed against the outer walls. An 8-foot double chemical rack occupies the center of each modular pair. Service to these benches includes multiple electrical outlets for 110 and 220 volt systems, air at 100 p.s.i., natural gas, cold water, steam at 15 p s i . , and nitrogen at 15 p.s.i. Distilled water is available from single taps in each laboratory. T o avoid duplicating analytical equipment which is frequently used, a centrally located quality control laboratory is VOL. 52, NO. 1
JANUARY 1960
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90'
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The first floor. Loborototies and offices are grouped at the front with direct routes to operating areas
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A maintenance shop (12 by 24 feet), conveniently located adjacent to the receiving, laboratory, and pilot plant areas, is staffed by two full-time men. T h e equipment is limited to a few small machine tools, a good assortment of hand tools, and a working supply of pipe fittings and other materials. The service end of the building includes a n electrical substation, locker and wash room, safety closet, and vending machines. A mechanical-equipment room contains inlet stations for all services, electrical switches for laboratory hoods, laboratory ventilation equipment, hot water heater, water softener, and condensate pump with tank. Pilot Plant Areas Hazardous Processes. The main pilot plant area of the building is the hazardous or explosion-proof process area which can accommodate flammable solvents and gases. Spark-producing operations are prohibited and electrical fixtures conform to the Class I. Group D code. This area: separated from the laboratory and service areas by a concrete-block fire wall. consists of nine 20
INDUSTRIAL AND ENGINEERING CHEMISTRY
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maintained. Typical control tests done here include microscopic examinations, determinations of viscosity, pH, per cent solids, melting points, and titrations. Responsibility for keeping u p this laboratory is delegated to one technician ; however, anyone is free to use the facilities. One room, where temperature and humidity is controllable over a moderate range, is set aside for special tests. I t is equipped with standard services and chemical benches because it doubles as a development laboratory when not required for temperature- and humidivcontrolled tests. For operations which cannot be conveniently carried out in the modules and which do not involve flammable chemicals, a nonhazardous operational laboratory (20 by 30 feet) is available. For example, a gas-fired spray dryer and special mechanical equipment designed for process studies are operated here. Services are conveniently located at several stations and auxiliary spot ventilation is provided through flcxible hoses and an overhead duct system. Two entries make the room easily accessible to both laboratory and service areas.
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by 24 foot bays. For better lighting, ventilation, communication, and working conditions, the two center bays are open. However, if it becomes desirable, they can be decked. Head room on the first, second, and third levels is 14, 14, and 12 feet, rcspectively, the total of which (40 feet) is adequate for most conceivable operations. .4 windoiv w-all for both lighting and explosion relief encloses one end of the process area. A corner bay on the first floor of this process area is subdivided into a solventdispensing and a high-ventilation workroom. The high vent room can actually be used as a walk-in hood because a floor fan changes the air once per minute. It can accommodate toxic or extra hazardous operations, but also it can be used for sloppy processes--two thirds of the floor is open grating. The solvent-dispensing room is used for handling solvents in small quantities, generally less than 5 gallons. I t can accommodate 24 55-gallon drums placed horizontally on racks. Solvents used in large quantities in the process area are handled directly from drums which are stored elsewhere when not in use.
PiLOT P L A N T BUILDING
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P R O C E S S AREA AND STORAGE
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One corner of the three-story process area is set aside for nonhazardous operations which require considerable head room O n the second floor, a onestory isolated hazardous process area is walled off and separately ventilated Left. Right. Most of the third floor, now used for storage, can b e converted into process floor space
The upper balconies, with the exception of three bays, are floored with l/dinch steel plate treated with a protective coating. If equipment which requires extensive head room is to be installed, these floors are considered expendable. Floors of the inside bays on the upper levels are of poured reinforced concrete for higher load bearing. A 2-inch angle iron is welded to the outside edge of all balconies to prevent spillage to lower levels, and railings are backed with expanded metal screen for added protection. O n the second story, a separately ventilated, hazardous-operating room is walled off. This is an isolated area which is now used for drying and dustproducing operations including grinding, and screening. Adjacent to this room is a walk-in cooler for storing chemical
intermediates, products, or raw materials at 40' F. Most of the third floor and a part of the second is now used for storing items such as idle process equipment, spare parts, chemicals, and containers. However, these storage areas will be shifted as demands for process floor space increase. Nonhazardous Processes. Another three-story area is provided for nonhazardous operations which may require considerable head room. Spark-producing operations are permitted, but flammable solvents and gases are not. Except for catwalks on two sides, the upper levels are open; however, decks or grating can be added. Also, if future operations do not demand height, each level may be used as a single floor. The ground floor of this nonhazardous
Each single module is designed for one technical man and his assistants
area contains a walk-in high-capacity fume hood and chemical bench. T h e area is well ventilated, the floor is sloped to an open trench for good drainage, and complete service panels are available at several locations. Building Services A roomy receiving area links working areas, the elevator, dock, and maintenance shop. The truck-height receiving dock, sheltered by an overhanging cantilever roof, can be used to store drums and cylinders. An elevator (10 by 12 feet) in the receiving area serves all floors, and space on the second and third floors, directly above the receiving area, houses service equipment including distilled water and ventilation equipment for make-up air to the three-story process area.
The main pilot plant area is the hazardous explosionproof accommodatesflammable solvents and gases VOL. 52, NO. 1
JANUARY 1960
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The isolated hazardous room on the second story i s now used for drying and dust-producing operations such as grinding and screening
Services for the laboratories (ventilation, electrical, hot. cold, and distilled water, nitrogen, natural gas and air at 100 p.s,i.) are manifolded from main headers above the suspended false ceilings of the 8-foot corridors Except for ventilation ducts. all lines pass down in the corridor-side wall and tee off to feed the hoods and chemical benches in the laboratory. Each service station is available for maintenance through an easily removed transite panel. Ventilation ducts enter overhead and branch out over each laboratory. The main air supply is set at 70' F.. but temperature in each laborator! is adjustable by thermostatically controlled tempering coils. Air is not recy-cled, but rather exhausted through the fume hoods by blowers which are located on the open roof, This arrangement minimizes noise. For the process areas, inlet air is preheated to 65" F. with make-up heat supplied by unit heaters. Inlets are imbedded in the wall at ceiling height, and distribution ducts are restricted to service areas of the second and third floors. Here also, air is not recycled, but rather exhausted at ground floor level through a series of six systems. Normal air change is once in 5 minutes, but this can be increased to 3 minutes by 4000-cubic foot per minute floor fans in the outer walls. The hazardous process area is always under a negative air pressure with respect to laboratory areas. I n emergency or during charging or draining operations, supplementary ventilation is provided by a series of 1500cubic foot per minute exhaust blowers, each of which is equipped with flexiblehose takeoffs at all floor levels. Similar systems are available in several of the laboratories. Utilities to the first and second floors are supplied by main service headers below the first balcony. Thus, any bay
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Each cantilever kettle has instrumented stream- and watertemDerature control. Service pipes are generally behind instiument panels
on these floors can be easily serviced. Also, two vertical headers suppll- stations and a point for future diswibution at the third deck. Electrical conduits for permanznt equipment, located in a bank directly above the service heads, follow the same distribution pattern. For portable equipment, however, receptacles carrying 110, 220, and 440 volts are available from conduits buried in the concrete floor. Light switches and circuit breakers are outside the process area. The building is served by a sanitary drain system and a chemical system which is treated in a lime pit before discharge to the city sewer. All floors are pitched to ventilated drain trenches which manifold to the chemical drain systzm. Process Equipment
Below the first balcony, six batchwise chemical reactors and two fractionating systems are permanently installed-tJvo per bay. They are mounted above 9foot wide grated floor trenches where spills are readily flushed and floors can be kept dry. Cantilever supports permit maximum access to each unit with complete freedom in charging and draining. Kettles contain instrumented steam and water-temperature controls, and service piping is generally behind the instrument panel and away from the reactors. These units, which vary from 5- to 100-gallon capacities, operate at pressures u p to 300 p.s.i. and are of glasslined steel, Monel, or stainless steel. Modifications are made as needed and generally include such changes as adding a hot-oil heater, refrigeration unit, pumps for adding reactants, or heat exchangers for reflux cooling. I n the remaining open bays and upper balconies, special process systems and continuous operations are installed.
INDUSTRIAL A N D ENGINEERING CHEMISTRY
Because the policy of operation emphasizes both flexibility and portability, unused equipment is usually stored on the upper balconies. Standard proccss equipment is generally sized to the requirements of a 20-gallon reactor which, with one exception. is the largest permanently installed kettle. Included in this equipment are items such as heat exchangers, pumps, filters, centrifuges. tanks, grinders, mixers, and ovens. Safety Features
A4n automatic water sprinkler s)stem covers the entire building, and each spray head is individually operated. Dry-chemical and carbon dioxide fire extinguishers ai e strategically located throughout the building. the largest of which is a 300-pound cart mounted unit in the hazardous process area. Fire blankets, safety showers, and eyewash fountains are located in all working areas. Water for the shoners and fountains runs a t a temperature of 90' F. because temperatures of 40° to 50' F. are unbearably cold for prolonged flushing. A portable bathtub is also available for submerged flushing of chemical burns. Alarms signal failure of ventilating units during operation, and also indicate overheating of the chemical-storage cooler. Battery-operated lights. placed at strategic positions, flash if power fails. An intercom system is provided specifically for shift work when only two or three individuals occupy the building. Thus, workers can operate safely in isolated areas without loss of contact. During the day, this system is used as an auto-call system. RECEIVED for review October 23, 1958 ACCEPTED August 10, 1959 Division of Industrial and Engineering Chemistry, 134th Meeting, ACS, Chicago, Ill., Sept. 7-12, 1958.
