Maximum temperature for technical reasons

Maximum temperature for technical reasons (MTT) is the boiling point in an open system. For a closed system, it is the temperature at the maximum permissible pressure, that is, the set pressure of a safety valve or bursting disk. 

The maximum allowed pressure of 100 bar will be reached at approximately 240 °C this temperature will be taken as the maximum temperature for technical reasons (MTT). 

Feed by portions this method, presented in Section 7.8.1, is obviously only applicable to discontinuous processes as semi-batch. It reduces the amount of reactant present in the reactor, that is, the accumulation and therefore the energy that may be released by the reaction in case of loss of control. The amount allowed in one portion can be determined in such a way that the maximum temperature of the synthesis reaction (MTSR) does not reach a critical level as the maximum temperature for technical reasons (MTT) or the temperature at which secondary reactions become critical (TD24). The difficulty is to ensure that an added portion has reacted away, before adding the next portion. Generally, the feed control is performed by the operator, but can also be automated. 

MTSR maximum temperature of synthesis reaction MTT maximum temperature for technical reasons... 

Beside all technical reasons the big advantage of a pneumatic test is, that the steam drums can remain within the line because first we have no additional load for the bearing and only small adjustments (for the connection with the pressurisation unit and the tightening of the man ways for the applied low temperature gas test) have to be done to make the drum ready for a pneumatic loading. The pressurised air is available in every paper mill and even if the maximum pressure does not fit, the use of a compressor or pressure bottles produce no problems. 

The data concerning hydrogen adsorption in carbon materials at room temperature are scattered over a wide range. The reasons for these discrepancies can be attributed to the difficulty in measuring the hydrogen uptake and to the big differences in the sample quality. Unfortunately it seems obvious that all the reproducible results concern maximum storage capacities of approximately 1 wt% at 298 K far less than required for technical applications. 

The space velocity, often used in the technical literature, is the total volumetric feed rate under normal conditions, F o(Nm /hr) per unit catalyst volume (m X that is, PbF o/W. It is related to the inverse of the space time W/F g used in this text (with W in kg cat. and F q in kmol A/hr). It is seen that, for the nominal space velocity of 13,800 (m /m cat. hr) and inlet temperatures between 224 and 274 C, two top temperatures correspond to one inlet temperature. Below 224 C no autothermal operation is possible. This is the blowout temperature. By the same reasoning used in relation with Fig. 11.5.e-2 it can be seen that points on the left branch of the curve correspond to the unstable, those on the right branch to the upper stable steady state. The optimum top temperature (425°C), leading to a maximum conversion for the given amount of catalyst, is marked with a cross. The difference between the optimum operating top temperature and the blowout temperature is only 5°C, so that severe control of perturbations is required. Baddour et al. also studied the dynamic behavior, starting from the transient continuity and energy equations [26]. The dynamic behavior was shown to be linear for perturbations in the inlet temperature smaller than 5°C, around the conditions of maximum production. Use of approximate transfer functions was very successful in the description of the dynamic behavior. 

For a variety of technical reasons the development of aromatic polyamides was much slower in comparison. Commercially introduced in 1961, the aromatic polyamides have expanded the maximum temperature well above 200°C. High-tenacity, high-modulus polyamide fibers (aramid fibers) have provided new levels of properties ideally suited for tire reinforcement. More recently there has been considerable interest in some new aromatic glassy polymers, in thermoplastic polyamide elastomers, and in a variety of other novel materials. 

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