Multipurpose

Allow the use of standardized multipurpose equipment for the production of a variety of products from the same plant. 

To examine a sample by inductively coupled plasma mass spectrometry (ICP/MS) or inductively coupled plasma atomic-emission spectroscopy (ICP/AES) the sample must be transported into the flame of a plasma torch. Once in the flame, sample molecules are literally ripped apart to form ions of their constituent elements. These fragmentation and ionization processes are described in Chapters 6 and 14. To introduce samples into the center of the (plasma) flame, they must be transported there as gases, as finely dispersed droplets of a solution, or as fine particulate matter. The various methods of sample introduction are described here in three parts — A, B, and C Chapters 15, 16, and 17 — to cover gases, solutions (liquids), and solids. Some types of sample inlets are multipurpose and can be used with gases and liquids or with liquids and solids, but others have been designed specifically for only one kind of analysis. However, the principles governing the operation of inlet systems fall into a small number of categories. This chapter discusses specifically substances that are normally liquids at ambient temperatures. This sort of inlet is the commonest in analytical work. 

The development section serves as an intermediary between laboratory and industrial scale and operates the pilot plant. A dkect transfer from the laboratory to industrial-scale processes is stiH practiced at some small fine chemicals manufacturers, but is not recommended because of the inherent safety, environmental, and economic risks. Both equipment and plant layout of the pilot plant mirror those of an industrial multipurpose plant, except for the size (typically 100 to 2500 L) of reaction vessels and the degree of process automation. 

In order to make a multipurpose plant even more versatile than module IV, equipment for unit operations such as soHd materials handling, high temperature/high pressure reaction, fractional distillation (qv), Hquid—Hquid extraction (see Extraction, liquid-liquid), soHd—Hquid separation, thin-film evaporation (qv), dryiag (qv), size reduction (qv) of soHds, and adsorption (qv) and absorption (qv), maybe iastalled. 

Batchwise operated multipurpose plants are per defmitionem the vehicle for the production of fine chemicals. There are, however, a few examples of fine chemicals produced ia dedicated, coatiauous plants. These can be advantageous if the raw materials or products are gaseous or Hquid rather than soHd, if the reaction is strongly exothermic or endothermic or otherwise hazardous, and if the requirement for the product warrants a continued capacity utilization. Some fine chemicals produced by continuous processes are methyl 4-chloroacetoacetate [32807-28-6] C H CIO [32807-28-6], and malononittile [109-77-3] C2H2N2, made by Lonza dimethyl acetonedicarboxylate [1830-54-2] made by Ube and L-2-chloropropionic acid [107-94-8] C2H C102, produced by Zeneca. 

Fig. 2. Schematic of a multipurpose fine chemicals plant. Computer-assisted process control is utilized.

The production building is only one part of a full-fledged fine chemicals plant. Apart from the multipurpose plant building there is usually an office and R D building, the warehouse, the maintenance shop, tank farms, the iaciaerator, and wastewater treatment faciUties. 

Figure 3 shows the capacity utilization resulting from the production program ia a multipurpose plant. The aimual percentage of occupation is shown on the x-axis reflecting the overall busiaess condition, and the level of equipment utilization is shown on thejy-axis, reflecting the degree of sophistication of the fine chemicals to be produced. Several conclusions can be drawn ...

Fig. 3. Multipurpose plant capacity utilization where D represents products A, B, C, D, and E U the changeovers and X the time the plant was idle.

Quality Control. Because fine chemicals are sold according to specifications, adherence to constant and strict specifications, at risk because of the batchwise production and the use of the same equipment for different products ia multipurpose plants, is a necessity for fine chemical companies. For the majority of the fine chemicals, the degree of attention devoted to quahty control (qv) is not at the discretion of the iadividual company. This is particularly the case for fine chemicals used as active iagredients ia dmgs and foodstuffs (see Fine chemicals, standards). Standards for dmgs are pubHshed ia the United States Pharmacopeia (USP) ia the United States (6) and the European Pharmacopeia ia Europe (7). 

Another quaHty control problem of multipurpose plants is the clean out for a product change. A test for residual cleaning solvents in the ppm level is a necessity. The best vaHdation of the cleaning process is to develop an analytical method that is able to find the previous product in the new product at a level of not more than 1 ppm. Tests should be mn on at least the first three batches. 

Cost Calculation. The main elements determining production cost are identical for fine chemicals and commodities (see Economic evaluation), a breakdown of production cost is given in Table 2. In multipurpose plants, where different fine chemicals occupying the equipment to different extents are produced during the year, a fair allocation of costs is a more difficult task. The allocation of the product-related costs, such as raw material and utiHties, is relatively easy. It is much more difficult to allocate for capital cost, labor, and maintenance. A simplistic approach is to define a daily rent by dividing the total yearly fixed cost of the plant by the number of production days. But that approach penalizes the simple products using only part of the equipment. 

A generic multipurpose fluidized bed is illustrated in Figure 2 (1). The soHds are contained in a vessel and gas is introduced into the system via a distributor, which is typically a drilled plate at the bottom of the vessel. A plenum chamber is provided below the distributor plate. The height of the soHds level above the distributor is called the bed height, and the vertical space above the bed height is called the freeboard. A splash zone may exist as a transition between the bed and freeboard. Cyclones, located either in the freeboard or external to the vessel, are used to remove soHds from the gas stream. Diplegs can return entrained soHds directly to the bed. 

Fig. 2. Multipurpose fluidized bed where 1 represents the sheU 2, soHd particles 3, the blower 4, the gas distributor 5, the heat exchanger for fluidizing gas 6, internal heating or cooling 7, external heating or cooling 8, cyclones 9, the soHds feeder 10, soHds offtake 11, Hquid feed 12, the freeboard 13, the...

The most common VI improvers are methacrylate polymers and copolymers, acrylate polymers (see Acrylic ester polymers), olefin polymers and copolymers, and styrene—butadiene copolymers. The degree of VI improvement from these materials is a function of the molecular weight distribution of the polymer. VI improvers are used in engine oils, automatic transmission fluids, multipurpose tractor fluids, hydrautic fluids, and gear lubricants. Their use permits the formulation of products that provide satisfactory lubrication over a much wider temperature range than is possible using mineral oils alone. 

Lactic acid is generally recognized as safe (GRAS) for multipurpose food use. Lactate salts such as calcium and sodium lactates and esters such as ethyl lactate used in pharmaceutical preparations are also considered safe and nontoxic (7). The U.S. Food and Dmg Administration fists lactic acid (all isomers) as GRAS and sets no limitations on its use in food other than current good manufacturing practice (46). 

In addition to their automotive use, PAO oils also find appfication in industrial and aircraft hydraufic fluids, gear oils, compressors, and environmentally sensitive appfications. They are also used in multipurpose greases for army, navy, nuclear, and industrial appfications. Expanding use has led to a growth rate of PAO production from 1985 to 1990 of 19% per year (28). 

Although most greases offer some inherent protection against msting, additives, eg, amine salts, sodium sulfonate, cycloparaffin (naphthenate) salts, esters, and nonionic surfactants (qv), are often used to provide added protection against water and salt-spray corrosion. A dispersion of sodium nitrite has been particularly effective in some multipurpose greases. 

Multipurpose pigments for paint, gravure ink, screen ink, paper coatings, plastisol, candles, plastics, and many other appHcations. Multipurpose pigments for paint, screen ink, paper coatings, plastisol, gravure ink, plastics, and many other appHcations. 

Isopropylnaphthalenes produced by alkylation of naphthalene with propjdene have gained commercial importance as chemical intermediates, eg, 2-isopropylnaphthalene [2027-17-OJ, and as multipurpose solvents, eg, mixed isopropylnaphthalenes. Alkylation of naphthalene with alkyl haUdes (except methyl hahdes), acid chlorides, and acid anhydrides proceeds in the presence of anhydrous aluminum chloride by Friedel-Crafts reactions (qv). The products are alkylnaphthalenes or alkyl naphthyl ketones, respectively (see Alkylation). 

Mixtures containing various concentrations of mono-, di-, and polyisopropylnaphthalenes have been prepared by treating molten naphthalene with concentrated sulfuric acid and propjiene at 150—200°C followed by distillation (39). Products comprised of such isomeric mixtures have extremely low pour points, ie, ca —50° C, are excellent multipurpose solvents, and have been evaluated as possible Hquid-phase heat-transfer oils. 

A multipurpose canister (MFC) is planned for the transportation, storage, and disposal of spent fuel, minimising the amount of handling requited. 

Most aroma chemicals are relatively high boiling (80—160°C at 0.4 kPa = 3 mm Hg) Hquids and therefore are subject to purification by vacuum distillation. Because small amounts of decomposition may lead to unacceptable odor contamination, thermal stabiUty of products and by-products is an issue. Important advances have been made in distillation techniques and equipment to allow routine production of 5000 kg or larger batches of various products. In order to make optimal use of equipment and to standardize conditions for distillations and reactions, computer control has been instituted. This is particulady well suited to the multipurpose batch operations encountered in most aroma chemical plants. In some instances, on-line analytical capabihty is being developed to work in conjunction with computer controls. 

Economic Aspects. Prices for pyromeUitic acid were about 14/kg in 1994. The dianhydride sold for about 19—25/kg depending on purity, and prices of the dianhydride ground to a fine 3-p.m size were 2/kg higher (153). Production amounts are not released and are dictated by market needs. The use of some multipurpose units to make this product means that the amounts produced are highly variable. 

Available Forms. Phthalocyanines are available as powders, in paste, or Hquid forms. They can be dispersed in various media suitable for aqueous, nonaqueous, or multipurpose systems, eg, polyethylene, polyamide, or nitrocellulose. Inert materials like clay, barium sulfate, calcium carbonates, or aluminum hydrate are the most common soHd extenders. Predispersed concentrates of the pigments, like flushes, are interesting for manufacturers of paints and inks (156), who do not own grinding or dispersing equipment. Pigment—water pastes, ie, presscakes, containing 50—75% weight of water, are also available. 

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