Temperature extremes, operation

The unit Kureha operated at Nakoso to process 120,000 metric tons per year of naphtha produces a mix of acetylene and ethylene at a 1 1 ratio. Kureha s development work was directed toward producing ethylene from cmde oil. Their work showed that at extreme operating conditions, 2000°C and short residence time, appreciable acetylene production was possible. In the process, cmde oil or naphtha is sprayed with superheated steam into the specially designed reactor. The steam is superheated to 2000°C in refractory lined, pebble bed regenerative-type heaters. A pair of the heaters are used with countercurrent flows of combustion gas and steam to alternately heat the refractory and produce the superheated steam. In addition to the acetylene and ethylene products, the process produces a variety of by-products including pitch, tars, and oils rich in naphthalene. One of the important attributes of this type of reactor is its abiUty to produce variable quantities of ethylene as a coproduct by dropping the reaction temperature (20—22). 

Synthetics are commonly employed only when their higher cost is justified by extreme temperatures or by need for special properties which caimot be achieved with petroleum greases. Severe temperature and operating requirements have led to a broad range of synthetic greases for military use (54). Comparison of typical temperature limits are given in Table 9. 

Sohd tantalum capacitors have a high volumetric capacitance which makes them attractive for use in miniaturized electronic systems like cellular telephones, hand-held video cameras, and personal computers. The insensitivity of their capacitance to temperature and their abiUty to operate at temperature extremes explains why these devices are used in such harsh environments as automobile engine compartments. Sohd tantalum capacitors are extremely rehable and, therefore, are often the capacitor of choice in critical appHcations like spacecraft electronics, pacemakers, and safety equipment. 

Plastics will continue to be required in space applications from rockets to vehicles for landing on other planets. The space structures, reentry vehicles, and equipment such as antennas, sensors, and an astronaut s personal communication equipment that must operate outside the confines of a spaceship will encounter bizarre environments. Temperature extremes, thermal stresses, micrometeorites, and solar radiation are sample conditions that are being encountered successfully that include the use of plastics. 

Perhaps the most striking phenomenon encountered in outer space is the wide variation in temperature that can be experienced on spacecraft surfaces and externally located equipment. Temperatures and temperature gradients not ordinarily encountered in the operation of ground or airborne structures and equipment are ambient conditions for spacecraft equipment. On such hardware, not suitably protected externally or housed deep within the space vehicle in a controlled environment, these temperature extremes can wreak destruction. Designers of earthbound... 

As expected, heat exchanged per unit of volume in the Shimtec reactor is better than the one in batch reactors (15-200 times higher) and operation periods are much smaller than in a semibatch reactor. These characteristics allow the implementation of exo- or endothermic reactions at extreme operating temperatures or concentrations while reducing needs in purifying and separating processes and thus in raw materials. Indeed, since supply or removal of heat is enhanced, semibatch mode or dilutions become useless and therefore, there is an increase in selectivity and yield. 

Reaction rates may often be improved by the use of more extreme operating conditions. More extreme conditions may reduce inventory appreciably. However, more extreme conditions bring their own problems, as will be discussed later. A very small reactor operating at a high temperature and pressure may be inherently safer than one operating at less extreme conditions because it contains a much lower inventory. A large reactor operating close to atmospheric temperature and pressure may be safe for different reasons. 

If a safety function does not apply, the horizontal line is continued through the safety function without branching. For this example, the upper branch continues through the second function, where the operator notices the high temperature. If the high-temperature alarm operates properly, the operator will already be aware of the high-temperature condition. The sequence description and consequences are indicated on the extreme right-hand side of the event tree. The open circles indicate safe conditions, and the circles with the crosses represent unsafe conditions. 

This technology cannot be located near noise-sensitive areas. The operating system does not work well in temperature extremes, such as below 30 or above 100°F. The technology is ex situ, requiring soil excavation. The technology changes the physical characteristics of fine-grained soils such as clay and topsoil. 

These parameters are determined by testing BEMs conditioned at the required extreme operational temperatures [15]. 

Catalytic combustion for gas turbines has received much attention in recent years in view of its unique capability of simultaneous control of NOX) CO, and unbumed hydrocarbon emissions.1 One of the major challenges to be faced in the development of industrial devices is associated with the severe requirements on catalytic materials posed by extreme operating conditions of gas turbine combustors. The catalytic combustor has to ignite the mixture of fuel (typically natural gas) and air at low temperature, preferably at the compressor outlet temperature (about 350 °C), guarantee complete combustion in few milliseconds, and withstand strong thermal stresses arising from long-term operation at temperatures above 1000°C and rapid temperature transients. 

At first, only two conflict objectives are considered the minimal utility consumption and the maximal flexibility to all source-stream temperatures. And then the third objective, the minimal number of matches, would be appended. Results of two-phase fuzzy optimization with preference intervals of [2550, 12750] or [2550, 8850] for utility, [0, 150], [40, 90] or [40, 70] for flexibility, and [4, 7] for unit numbers, along with either or not considering restrictions on heat loads at extreme operating points, are listed in Table 4. The resulting HEN structures are also depicted in Fig. 2. Notably, the reduced range of flexibility, [40, 90], implies that the required minimum tolerance for temperature deviation is at least 40 K and a tolerance of maximum temperature deviation for 90 K... 

The first question to be answered is whether or not the sample is volatile enough to be analyzed by GC. GC columns are currently available with upper temperature limits of around 350 °C. Hence, compounds should be sufficiently volatile at this temperature to be analyzed by GC. A second requirement for the sample, which becomes the more relevant the higher the temperatures used, is the thermal stability of the sample, both in the column, as well as in the injector, which in conventional GC is operated at a temperature slightly above that of the column. Because of the limited stability of organic substances at higher temperatures, extremely high temperatures do not seem to be very... 

Temperature The operating temperature of a biofilter is primarily controlled by the inlet gas temperature. The recommended operating temperature range tor high destruction efficiency is between 20° to 40° C, with an optimum temperature of 37° C (98° F). At lower temperatures, the bacteria growth will be limited, and at extremely low temperatures the bacteria could possibly be destroyed. At temperatures above the recommended range, the bacteria s activity is also impaired. Extremely high temperatures will destroy the bacteria within the filter bed. 

Thermal considerations are paramount for ATFs. A great deal of friction is produced, which generates heat and high-temperature spikes at the torque converter this will damage the fluid. ATF is designed to operate at temperatures around 95°C. At the torque converter, under extreme conditions, temperatures can reach 120°C. A transmission fluid should be designed to handle these temperature extremes. The transmission fluid will quickly break down above 120°C. Temperature spikes in the torque converter have been known to go above 120°C. 

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