Chemical industry processes

ter Qua.litySta.nda.rds, The first step in water quahty standards is stream use classification. The individual states must decide what the uses of their water will be. The four categories, as defined by the EPA, are Class A, primary water contact recreation Class B, propagation of desirable aquatic life Class C, pubHc water suppHes prior to treatment and Class D, agricultural and industrial uses. States may vary the definition of these classes to meet their own needs. The second step is to develop water-quaHty criteria. This is the specific concentration of a pollutant that is allowable for the designated use. 

Effluent Guidelines and Standards. The Clean Water Act requires specific levels of control for dischargers. These are outlined in the Effluent Guidelines and Standards for various industrial categories. These standards limit the discharge of pollutants, usually in terms of a unit weight of pollutant per unit of either product or raw material, rather than a concentration in the discharge stream, in order to eliminate the use of dilution to meet limits. 

The effluent standards require two levels of treatment best practicable control technology (BPCT) and best available control technology (BACT). New standards covering additional industries are stiU being issued. Of special concern to the chemical industry are the following Hsted categories  

Part 403 general pretreatment regulations for existing and new sources of pollution Part 411 cement manufacturing point source category Part 413 electroplating point source category 

Part 414 organic chemicals, plastics, and synthetic fibers (OCPSF) 

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DILLON Materials Selection for the Chemical Process Industries freeman Hazardous Waste Minimization... 

Flocculating agents differ from other materials used in the chemical process industries in that their effect not only depends on the amount added, but also on the concentration of the solution and the point at which it is added. The process streams to which flocculants are added often vary in composition over relatively short time periods. This presents special problems in process control. 

Chemical Applications. The chemical processing industry uses large amounts of granular and fine powder PTFE. Soft packing appHcations are manufactured from dispersions, and hard packings are molded or machined from stocks and shapes made from granular resin. 

Chemical Properties. A combination of excellent chemical and mechanical properties at elevated temperatures result in high performance service in the chemical processing industry. Teflon PEA resins have been exposed to a variety of organic and inorganic compounds commonly encountered in chemical service (26). They are not attacked by inorganic acids, bases, halogens, metal salt solutions, organic acids, and anhydrides. Aromatic and ahphatic hydrocarbons, alcohols, aldehydes, ketones, ethers, amines, esters, chlorinated compounds, and other polymer solvents have Httle effect. However, like other perfluorinated polymers,they react with alkah metals and elemental fluorine. 

Induction heating is used to heat steel reactor vessels in the chemical process industry (5). The heat produced in the walls is conducted to the material within. Multisectioned cods are used to provide controlled heat input to the process material as it passes through the reactor. Figure 6 illustrates a cross section of such a typical installation. 

K. G. Webley, "Induction Heating of Steel Reactor Vessels," Chemical Process Industry Symposium, AlCHE, Philadelphia, Pa., June 5—8,1978. 

R. Norris Shreve andj. A. Brink, "Chemical Process Industries," in Perry s Chemical Engineers Handbook, 4th ed., McGraw-HiU Book Co., Inc., New York, 1977. 

The purpose of hazard analysis and risk assessment ia the chemical process industry is to (/) characterize the hazards associated with a chemical facihty (2) determine how these hazards can result in an accident, and (J) determine the risk, ie, the probabiUty and the consequence of these hazards. The complete procedure is shown in Figure 1 (see also Industrial hygiene Plant safety). 

Coal, considered a soHd hydrocarbon with a generic formula of CHq g, was explored by numerous workers (24—31) as a feedstock for the production of acetylene. Initially, the motivation for this work was to expand the market for the use of coal in the chemical process industry, and later when it was projected that the cost of ethylene would increase appreciably if pretroleum resources were depleted or constrained. 

In the United States, the acetylene production exceeded 450, 000 t/yr between 1963 and 1970, but then declined until it hit a minimum production level below 150, 000 t/yr in 1982. Of this production, about 40,000 t were dedicated to industrial use, ie, welding, etc. Thus only slightly more than 100,000 t were produced for the chemical process industry. Figure 14 illustrates the 17-year decline in acetylene production and indicates the reduced derivative demand to which the accumulated decline is attributed (37). 

Table 1. Exposure Sources in the Chemical Process Industry...

Chemical-grade limestone is a pure type of high calcium or dolomitic limestone used by the chemical-process industry or where exacting chemical requirements ate necessary. It contains a minimum of 95% total carbonate. In a few areas of the United States this minimum may be extended to 97 or 98%. 

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