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PHILIP KRONOWITT Toms River-Cincinnati Chemical Corp., Toms River, N. J.
Fine Chemicals
- Batch Processing
In the ideal, fine organic chemical plant of the future, all operations will be preprogrammed and monitored through the central control boards 0
Manual labor will be practically eliminated
0
Maintenance will be largely preventative
0
Brawn will be replaced by brains
I s THE m m u F . x r u R E of a variety of synthetic organic fine chemicals, practically every unit process known in the synthesis of organic compounds is used. Basic raw materials are processed into intermediates through such steps as sulfonation. nitration, halogenation, oxidation. reduction, amidation, and diazotization. These intermediates are coupled or condensed, hydrolyzed, alkylated, esterified, and finally precipitated, filtered, dried, ground, mixed, and packaged. hiany of the steps are performed in solvents: which have to be recovered by distillation. Secondary side reactions, difficult to control, produce other compounds which have to be removed by various purification process steps. T h e compound may have to be re-sludged, dissolved, acidified or made alkaline, re-precipitated, filtered, washed, often employing a n appropriate solvent. I t ma)- have to be re-crystallized, acidfractionated, or sublimed. Equipment employed in these processes are reactor vessels, stills, condensers, filters, dryers, grinders, mixers, pumps, and receiving tanks. Reactor vessels are mostly closed pressure vessels with stirrers. for pressures ranging from 2 to 3 mm. absolute to 1000 to 1200 pounds per sq. in. pressure. T h e reaction temperature may range from -25" C. to + W o o to 60OoC.performed through jacket or internal coil cooling Lrith brine or water, heating through hot water, steam? o:l! Doi\-therm. or electric resistance heat.
Material of construction. depending on the process requirement. may be C. I. steel, stainless steel. nickel. protective lining of glass, rubber. plastic, brick. or lead. Basic Design Principles
T h e primary object of any commercial manufacturing enterprise is to produce goods of the quality and quantity required by the market, at a cost to which a fair return of the capital investment must be added. Cost control must start at the research and process development stage. The size of batches, the time required for the process cycle. the operating temperatures. and pressures will have important bearing on the product cost. Control requirements of exothermic and endothermic reactions will determine heating and cooling requirements and influence the capital and operating costs of the process. Careful selection of the correct procedures after evaluating all factors entering into the cost picture is the first step toward achieving the primary goal. The second step \vi11 be the layout. selection, and design of equipment and housing. T h e layout must be arranged for convenient operation and material handling. T h e value of uncrowded aisles, spacious equipment arrangement, and of the degree of comfort, dignity. and attractiveness must be balanced against the cost of investment. The higher cost of high quality equipment and buildings must be balanced Irith the
lower operating and maintenance cost and longer expected life. After the final decision as to products, processes, capacity, equipment selection. layout, and basic design philosophy is made. the actual design work can be started. The next important step is standardization of equipment, accessories, and building components as far as it is consistent with good design and operation requirements. \-ariation in sizes, design types, and material of construction will be large enough because of irreducible process requirements. They should not be needlessly increased by lack of careful control and consideration in thr design stage. M-henever manufacturer's standard equipment fulfills process and quality requirements, it should be selected in preference to special design. In the layout and design of the process equipment, the designers must bear in mind that the products, processes, and production quantities will, by necessity, deviate to a substantial degree from original design assumptions during the lifetime of the facilities. Market requirements fluctuate and change, products become obsolete and are replaced by new or improved producw. Minor and major changes due to process improvements will be unavoidable at some future date. Y o hard and fast rules nor formulae are available to calculate the cost cs. value of built-in flexibility; often the deVO1. 51, NO. 9
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SEPTEMBER 1959
987
cision has to be based on meager facts. However, long experience will guide intuitively the competent designer in the right direction.
Plant and Equipment Cost
Components of a plant manufacturing fine organic chemicals can be conveniently classified in four categories: process buildings and equipment; storage and distribution facilities; auxiliaries (administration offices, laboratories, steam plant, maintenance shop, cafeterias, wash and locker rooms, water supply, and sewage treatment plants) ; and land, roads, railroad trackage, and underground and overhead distribution lines (sewer, water, and steam). A few projects completed within the last 10 years indicate an average cost distribution of the four components, in the order listed above, as follows: 60%, range 50 to 65%; 6%, range 5 to 10%; %yo, range 20 to 30%; and 8y0,range 5 to 10%. The percentage may vary considerably with the size of the project. Other factors affecting the relative cost will be whether electric power, gas, and water are purchased, the extent of sewage treatment required, the extent of research carried out by your own personnel, or variation of storage requirements. Plant investment costs per employee will vary considerably with the size of the operation and the nature of processes. The average plant investment per employee in this industry will vary from $50 to $80,000 for plants built since 1950. These plants have more automation, more labor saving installations, and therefore investment cost per employee will run higher. Older plants, built at lower cost, but with higher number of operating personnel for the same output, will run as low as $30,000 investment per employee. The ratio of plant investment cost to annual production value will vary from 1.5 to 3.0 for a multi-product plant. Greater variety of products and more complicated processes involving numerous steps will increase while single products, continuous or semicontinuous processes, will reduce the ratio. Building costs will vary with size, type of construction, quality of comfort (heating, lighting, ventilation, air conditioning), quality of floor, and wall finishes. For rough approximation, it can be reasonably assumed that in the cost of a process building, the cost of building (including elevators, sprinklers, lighting, heating) will represent approximately 30 to 40%, while process machinery, piping, and instrumentation will represent the balance of the costs. If part of the process equipment can
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be outdoor or semioutdoor t y i x : building costs will be substantially less. Steam generating plants vary from $5 to $8.00 per pound per hour capaciry. for medium pressure (100 to 500 pounds per sq. in.), for units varying between 50,000 to 2503000 pounds per hour capacit7;. The type of fuel burned (gas, oil, stoker, or pulverized coal firing) will influence the cost. Cost of waste water treatment facilities will depend on the type of treatment required. Treatment plants consisting of neutralization, sedimentation, oxidation, and chlorination will run approximately $250,000 to $400:000 per million gallons per day capacity. Factors Influencing Plant Investment and Operating Cost
The over-all cost of a plant, and to a large degree its operation cost, is essentially defined after the design is completed. While quick and economical execution of the plans and the efficient management of operations can contribute significantly to sound economies, they cannot overcome the handicap of uneconomical processes or of poor design and layout. The basic element of manufacturing costs are: depreciation, insurance, and taxes; salaries, wages, and fringe benefits; maintenance and operating supplies; fuel and energy costs; general expenses (communication, transportation, accounting, personnel, and welfare) ; and raw material costs. Only the last item varies in direct proportion with production, and other items are either entirely independent or vary only to a lesser degree. Production and inventory planning which can maintain near full occupancy of equipment and personnel, at even level, without excessively large inventories is the ideal goal, seldom achieved. Maintenance planning must emphasize preventive maintenance, minimizing shutdowns, breakdowns, and emergency repairs, which are always costly. Training of personnel in proper use and care of building, equipment, prevention of waste, spoilage, prevention of accidents and occupational disease by safe practices and suitable protective devices, clothing and sanitation, cleanliness and good housekeeping will be important factors in the efficient operation of any plant. Automation and Instrumentation. Continuous vs. Batch Processes
Automation and instrumentation began in this industry with the replacement of hand stirring of reaction vessels by mechanical devices at the beginning of this century and it has been continuing at an increasing rate ever since. Automatic temperature and pressure
INDUSTRIAL AND ENGINEERING CHEMISTRY
recording and control, fluid flow measurement and control has been part and parcel of process equipment for many years. Transportation, weighing and charging of raw material is continuously progressing toward automation? not only to reduce labor cost, but to safeguard against human fallibility. The development of analytical instruments that can be used on stream, will gradually replace the time consuming and costly procedure of laboratory analyses of samples taken by hand at various stages of the process. Development of fully continuous processes will be handicapped by the large number and type of unit operations involving comparatively small quantities. Ideal Plant of the Future
The modern fine organic chemical plant which will be built in the 1980’s, will differ vastly from the present ones. With the development of corrosion resistant materials for a wider range of chemicals, pressures, and temperatures, reactors will be of more uniform design and interchangeable. All raw materials, whether solid, liquid, or gas will be weighed, measured, and fed through a preprogrammed automatic control board. Reactor pressures and temperatures, speed of agitation, start and stop will be centrally controlled. Continuous stream analyzers or automatic periodic sample takers and analyzers will not only indicate and record the progress of reaction, but will automatically correct any deficiencies by adding the required reagents, varying speed, pressure, and temperature as preprogrammed. Operating records, materials charged, energies consumed, yields, and quality will be recorded, computed, and printed and be available upon completion of the process cycle through electronic computers. Transfer of reactor contents from one reactor to another, or to filtration, drying, mixing, or solvent recovery will be through centrally operated switch stations, all of which is preprogrammed and monitored through the central control boards. Manual labor will be practically eliminated from the operations and will be replaced by the programming and process control supervisors sitting i n the central control room dispatching instrument engineers and mechanics to trouble spots when the control board indicates failure. Maintenance will be largely preventive and inspection. Brawn will be replaced with brains, drudgery with imagination. RECEIVED for review April 17, 1959 ACCEPTED April 27, 1359 Division of Industrial and En ineering Chemistry, Symposium on Plant Eosts and Economics in the Chemical Process Industry, 135th Meeting, ACS, Boston, Mass., April 1959.
