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Show heaters and distillation reactors, the amount of heat transferred to the reactor and the rate at which heat is transferred to the reactor are among the important process paranleters. Improvements in the control of these process parameters will result in improvements in product quality, efficiency and minimization of gaseous emissions. For in-bed combustion fluidized bed reactors, improved control algoritluns could result in significant improvements in product quality. For these processes, not only are the amount of heat supplied to the process and the rate at which it is supplied important, but the combustion process inside the reactor also directly affects the product chemistry. Control of the combustion process results in control of product chemistry by regulation of chemical reactions involving the combustion off-gas and the product. Improvements in non-intrusive, in-situ measurements of conditions within the combustion reactor, whether it is a burner external to the reaction vessel that supplies heat to a process or an in-bed combustion process, are also needed. Run-time knowledge of combustion conditions, such as air/fuel mixtures and off-gas/eflluent compositions, enhances operating efficiencies, improves product quality, and reduces regulated emissions from combustion processes, especially in situations where multiple fuel sources (such as process off-gasses, fuel oils, refmery residue, and/or natural gas) are employed. 4.4.2 Development of Enhanced Heat Transfer Mechanisms Development of process control algorithms, and development of alternative materials and designs for vessel construction would enhance heat transfer for externally-heated processes. As the size of a process vessel increases, heat transfer linlitations generally become more pronowlced because while the surface area of a cylindrical vessel varies proportionally to the radius, the volunle of the vessel varies with the square of the radius. Heat transfer limitations can negatively affect process efficiencies as vessel sizes increase, and in many processes heat transfer is the limiting constraint on reaction vessel volume. 4.4.3 High-Temperature Separation Processes The production of high-temperature gasses during combustion processes in the chemical industry is widespread. It is sometimes necessary to do a separation on these streams, either to remove entrained particulate or to remove one or more gaseous components from the stream. Most often, separations involving gases are performed at temperatures that require cooling of the gaseous stream. If part of this cooled stream is to be used following the separation, it is often necessary to reheat the gas. This cooling-heating cycle loses heat that might have been used during the cooling step and requires additional heat during the heating step. These inefficiencies could be eliminated by using of high-temperature separation processes. One high-temperature gas separation concept involves the use of high-temperature membranes or molecular sieves, or both, to separate gasses at near the process temperature, thus eliminating the loss of heat during cooling and the conswnption of heat during reheating of the separation product(s). It is likely that technology development in this area would include developing new materials and advanced process design and control. 4.5 Glass Industry Glass was one of this country's first industries, locating here from Europe owing to abundant energy and raw material. Today's glass industry is a major user of energy. The glass industry constitutes one of the principal markets for natural gas, consuming over 188 billion cubic feet in 1994. This fuel has been preferred to other fossil fuels because of its operational cleanliness and flexibility. About 85 percent of the total energy used in the glass industry is supplied from natural gas, and about 14 percent comes from electricity. A small amount of oil is used in melting; however, its use is restricted to situations where gas is purchased on an interruptible basis and has been curtailed. Because of air emission concerns and some operating difficulties, oil use is usually discontinued as soon as gas again becomes available. Overall, about 75 percent of the natural gas conswned by the glass industry is used for melting; the balance is used for (a) downstream operations, \~:hich consist of fabrication into containers, flat glass, fiberglass, or a variety of objects (such as dinnenvare, kitchenware, television tubes, and laboratory ware), that are pressed and blown, and (b) finishing operations such as annealing and tempering. However, in the fiberglass segment, 55 to 60 percent of gas consumption is used for melting and refining; in the other segnlents, melting and refining account for 85 percent or more. 13 |