Vinyl chloride process

Figure 10.4 The oxychlorination step of the vinyl chloride process. (From Smith and Petela, Chem. Eng., 513 24, 1991 reproduced by permission of the Institution of Chemical Engineers.)...

A fiowsheet for this part of the vinyl chloride process is shown in Fig. 10.5. The reactants, ethylene and chlorine, dissolve in circulating liquid dichloroethane and react in solution to form more dichloroethane. Temperature is maintained between 45 and 65°C, and a small amount of ferric chloride is present to catalyze the reaction. The reaction generates considerable heat. 

Figure 10.5 The direct chlorination step of the vinyl chloride process using a liquid phase reactor. (From McNaughton, Chem. Engg., December 12, 1983, pp. 54-58 reproduced by permission.)...

Fig. 1. Principal steps in a balanced vinyl chloride process.

The ethylene-based, balanced vinyl chloride process, which accounts for nearly all capacity worldwide, has been practiced by a variety of vinyl chloride producers since the mid-1950s. The technology is mature, so that the probabiUty of significant changes is low. New developments in production technology will likely be based on incremental improvements in raw material and energy efficiency, environmental impact, safety, and process reUabiUty. 

By copolymerising the vinylidene chloride with about 10-15% of vinyl chloride, processable polymers may be obtained which are used in the manufacture of filaments and films. These copolymers have been marketed by the Dow Company since 1940 under the trade name Saran. Vinylidene chloride-acrylonitrile copolymers for use as coatings of low moisture permeability are also marketed (Saran, Viclan). Vinylidene chloride-vinyl chloride copolymers in which the vinylidene chloride is the minor component (2-20%) were mentioned in Chapter 12. 

Air-atmosphere furnaces, 22 290-291 Air atomization, in spray coating, 7 70-72 Air-atomizing sulfur burners, 23 659-660 Airbags, nylon, 19 766 Air-based balanced vinyl chloride process, 25 637, 640, 641, 645 Air-based ethylene oxidation, 20 643-646 Air bioremediation... 

Baking chocolate, theobromine and caffeine content, 6 367t Baking enzymes, 10 297 Baking furnaces, 12 734—735 Balanced vinyl chloride processes, in vinyl chloride manufacture, 25 634, 635,... 

Geomembrane blowing operations, 20 174 Geometric mean, 18 136 Geometric properties of fibers, 11 166-167 of staple fibers, 11 166-167 Geon balanced vinyl chloride process, 25 636, 672... 

Poly(vinyl chloride) processing industry Sweden ... 

Commercialization of a new vinyl chloride process has been announced. Instead of the traditional three-step production (see Section 6.3.4), it is based on ethane oxy-chlorination using HC1, 02, and Cl2 carried out over a CuCl-based catalysts.285 Overchlorinated products are dehydrochlorinated and hydrogenated (together with overchlorinated alkenes) in separate reactors these product streams are then led back to the oxychlorination reactor. 

Lakshmanan L, Biegler LT. A case study for reactor network synthesis the vinyl chloride process. Comput Chem Eng 1997 21 785. 

Fig. 10.11. Integrated EDC/vinyl chloride process. (Hydrocarbons Processing, p. 174, 1985 November. Copyright Gulf Publishing Company and used by permission of the copyright owner.)...

Simulate the vinyl chloride process (Problem 5.4) using Aspen Plus. Take the feed at room temperature and 20 psia. Operate the direct chlorination reactor at 65°C and 560 kPa. A distillation column removes the trichloroethane and the rest of the stream is sent to the furnace. Heat the stream to 1500 F so pyrolysis takes place. Cool the effluent from the furnace, and recycle the vapor (mostly HCl). Send the hquid (vinyl chloride and ethylenedichloride) to a distillation column for separation. 

The reactions for each step in the balanced vinyl chloride process are shown in equations 21-24. The chemical reaction for the direct chlorination step is... 

The earliest polymerization processes were either batch mode or semibatch. The semibatch method was used for products, where the two monomers differed greatly in reactivity, as in Union Carbide s early Dynel, acrylonitrile-vinyl chloride, process. Bulk, solution, and emulsion polymerization processes have also been developed for acrylonitrile and its copolymers. However, in recent years nearly every major acrylic fiber producer has used a continuous aqueous suspension process, employing a redox catalyst, followed by a series of steps, which includes slurry filtration and polymer drying. 

Figure 3.6 Flowsheet including the separation operations for the vinyl-chloride process.

Figure 3.7 Flowsheet with temperature-, pressure-, and phase-change operations in the vinyl-chloride process.

Throughout the synthesis of the vinyl chloride process, branches have been added to the synthesis tree in Figure 3.9 to represent the alternative flowsheets being considered. The bold branches trace the development of just one flowsheet as it evolves in Figures 3.3-3.8. Clearly, there are many alternative flowsheets, and the challenge in process synthesis is to find ways to eliminate whole sections of the tree without doing much analysis. By eliminating reaction paths 1 and 2, as much as 40% of the tree is eliminated in the first synthesis step. 

Stream Information. Directed arcs that represent the streams, with flow direction from left to right wherever possible, are numbered for reference. By convention, when streamlines cross, the horizontal line is shown as a continuous arc, with the vertical line broken. Each stream is labeled on the PFD by a numbered diamond. Furthermore, the feed and product streams are identified by name. Thus, streams 1 and 2 in Rgure 3.19 are labeled as the ethylene and chlorine feed streams, while streams 11 and 14 are labeled as the hydrogen chloride and vinyl-chloride product streams. Mass flow rates, pressures, and tempera-mres may appear on the PFD directly, but more often are placed in the stream table instead, for clarity. The latter has a column for each stream and can appear at the bottom of the PFD or as a separate table. Here, because of formatting limitations in this text, the stream table for the vinyl-chloride process is presented separately in Table 3.6. At least the following entries are presented for each stream label, temperature, pressure, vapor fraction, total and component molar flow rates, and total mass flow rate. In addition, stream properties such as the enthalpy, density, heat capacity, viscosity, and entropy, may be displayed. Stream tables are often completed using a process simulator. In Table 3.6, the conversion in the direct chlorination reactor is assumed to be 100%, while that in the pyrolysis reactor is only 60%. Furthermore, both towers are assumed to carry out perfect separations, with the overhead and bottoms temperatures computed based on dew- and bubble-point temperatures, respectively. 

Table 3.6 Stream Summary Table for the Vinyl-Chloride Process in Figure 3.19...

---