Balancing in Process Industries

Characteristic examples of industrial fast chemical reactions are the electrophilic polymerisation of isobutylene [7], its copolymerisation with isoprene [10], chlorination of olefins [17] and butyl rubber [18], ethylene hydrochlorination [17], sulfation of olefins [19], neutralisation of acidic and basic media [20], isobutene alkylation (production of benzines) [21-23], and so on. These examples of fast liquid-phase reactions and a variety of such processes assume a formal approach for their calculation and modelling, based on material and heat balance in the industrial implementation of respective products. It is a priori acknowledged that is not difficult to achieve an isothermic mode for fast chemical exothermic processes if you are aware of the process behaviour and can control it. 

The classification was developed mainly for use in balancing complex plants in process industries. The methods developed are based on the solvability analysis of sets of balance equations (Vaclavek et al. 1972, Crowe 1989) and on the analysis of stracture of balanced system (Vaclavek and Loucka 1976, Vdclavek and VosolsobS 1981). Systematic research by Mah and his coworkers in this area, poblished in a number of papers, is summarized by Mah in his monograph (Mah 1990), where also a comprehensive survey of the state of the art of classification can be found. 

Alternatives to oxychlorination have also been proposed as part of a balanced VCM plant. In the past, many vinyl chloride manufacturers used a balanced ethylene—acetylene process for a brief period prior to the commercialization of oxychlorination technology. Addition of HCl to acetylene was used instead of ethylene oxychlorination to consume the HCl made in EDC pyrolysis. Since the 1950s, the relative costs of ethylene and acetylene have made this route economically unattractive. Another alternative is HCl oxidation to chlorine, which can subsequently be used in dkect chlorination (131). The SheU-Deacon (132), Kel-Chlor (133), and MT-Chlor (134) processes, as well as a process recently developed at the University of Southern California (135) are among the available commercial HCl oxidation technologies. Each has had very limited industrial appHcation, perhaps because the equiHbrium reaction is incomplete and the mixture of HCl, O2, CI2, and water presents very challenging separation, purification, and handling requkements. HCl oxidation does not compare favorably with oxychlorination because it also requkes twice the dkect chlorination capacity for a balanced vinyl chloride plant. Consequently, it is doubtful that it will ever displace oxychlorination in the production of vinyl chloride by the balanced ethylene process. 

Distillation Columns. Distillation is by far the most common separation technique in the chemical process industries. Tray and packed columns are employed as strippers, absorbers, and their combinations in a wide range of diverse appHcations. Although the components to be separated and distillation equipment may be different, the mathematical model of the material and energy balances and of the vapor—Hquid equiUbria are similar and equally appHcable to all distillation operations. Computation of multicomponent systems are extremely complex. Computers, right from their eadiest avadabihties, have been used for making plate-to-plate calculations. 

Outside balanced seals permit sealing pressures up to about 150 psig. They offer the other benefits of outside seals, which make them popular in the food processing industry (Figure 13-7). 

In the food production and OTC (Over the Counter) Drug industries, like milk, soups, cough syrup, and juices, outside balanced seals are quite popular. Their design permits easy cleaning of the equipment without pump disassembly. These seals are prominent in the chemical processing industry because all metal components in the seal are located outside the fluid. This avoids problems of galvanic eorro.sion. 

Baines, D. (1984) Chem. Engr., London No. 161 (July) 24. Glass reinforced plastics in the process industries. Bendall, K. and Guha, P. (1990) Process Industry Journal (Mar.) 31. Balancing the cost of corrosion resistance. 

Material and Energy Balances in the Design of Industrial Reactors. The analysis of chemical reactors in terms of material and energy balances differs from the analysis of other process equipment in that one must take into account the rate at which molecular species are converted from one chemical form to another and the rate at which energy is transformed by the process. When combined with material and... 

The generation of the required reducing gas is very expensive because natural gas or low sulfur oil are used. Both of these fuels are in short supply and do not offer long-term solutions to the problem. However, in certain industrial processes, like petroleum refineries, a reducing gas could be readily available. Also, if a Claus sulfur recovery plant existed on-site, the concentrated SO2 stream could be sent to the Claus plant where it would mix with the H2S containing gas streams. Final adjustment of the H2S S02 ratio would be necessary. If the overall sulfur balance were favorable, the need for a reducing gas could be avoided. Either of these options could make the use of a recovery process economically attractive for industrial applications. 

The balance of the industrial ethyl alcohol is in demand as a solvent in personal care products (aftershave lotion, mouthwash), inks, cosmetics, detergents, household cleaners, pharmaceuticals, industrial coatings, and as a processing solvent. 

The development of the population balance approach has done much to further our understanding of CSD transients and instabilities which are observed in the plant and the laboratory. Advances in computing and control technology which have occurred in the chemical process industry together with the recognition that on-line CSD control might be achievable has led to an increased level of interest and investigation of this area. 

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