Single-reactor piping arrangement

To demonstrate this principle, we used a pipe attached to the outlet of the gear pump as the second reactor. The volume of this pipe was twice that of the gear pump, so that the residence time in the latter was reduced by two-thirds. To simulate the probable thermal situation in large-scale reactors, the temperature of the electrically heated pipe was raised to 350°C while the gear pump was maintained at 245°C. The advantages of this arrangement over a single reactor are shown in Table II. 

Many different loop reactor configurations are used in industrial processes. The loop can be either in a vertical (Phillips and Spheripol processes [72, 73]) or in a horizontal position (USl process). The pipe can also be bent into multiple legs to increase the reaction volume. Several loops can be arranged in series to produce bimodal polymer, as in the case of Spheripol and Borstar processes [74]. Alternatively, the series of loop reactors can be operated as one single unit to increase average residence time and throughput. 

Major economic improvements for SMART can be summarized as system simplification, component modularization, factory fabrication, direct site installation of components and reduced construction time. The integral arrangement of the primary reactor systems requires only a single pressurized vessel and removes large-sized pipes connecting primary components. The adoption of simplified passive systems provides a net reduction in the number of safety systems and drastically reduces the number of valves, pumps, wirings and cables, pipes, etc. 

Figure 12.5 A schematic diagram of some of the major elements of a typical low-pressure chemical vapor deposition system. Note that the entire process is typically contained within a safety enclosure because many of the reactants as process gases are either flammable or toxic. A toxic gas detector scans the interior of the enclosure, especially around the gas piping, for leaks. The scrubber reacts the source materials that are left over after passing through the reactor tube to render them harmless. Typically the valves for all sources are operated electronically so that the user does not need to open the safety enclosure except to load substrates on the susceptor. The system shown here includes a single substrate on a tilted susceptor. Batch processes are similar except in the arrangement of substrates in the reactor tube. Other reactor tube designs are also used. More specific reaction examples are given in Section 12.8.

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