Thermal intensification

Most of the chemical reactions in the process industry are temperature dependent. They are either exothermic or endothermic. As a consequence, it is often necessary to remove the heat generated by an exothermic reaction to control the reaction temperature and to avoid thermal runaway reactions or to suppress endothermic by-product reactions, for instance [8]. 

Therefore, many traditional designs, such as stirred tank reactors, incorporate heat transfer in the process (jacket, external or internal coil, etc.). However, in these devices, there is a significant distance between the heat transfer site and the site of the chemical reaction where heat is released. As a consequence semibatch mode is implemented while batch mode and/or systems are diluted. 

A comparison of the heat transfer performance of different reactors presented in Table 12.1 shows the main advantages of HEX reactors [10]. 

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Thermal intensification, reduction in pasteurization and cooking time rapid heating high potential for hybrid processing (with hot air vacuum, osmotic, freezing, IR/RF)... 

Thermal intensification, reduction in pasteurization and cooking time rapid heating... 

The simplest method of reduciag stresses and reactions is to provide additional pipe ia the system ia the form of loops or offset-bonds. When physical limitations restrict the use of additional bends, a multiple arrangement of several small-size pipe mns may sometimes be used. Owiag to stress intensification, the maximum stress generally occurs at elbows, bends, and Ts. Thus, heavier-walled fittings may reduce the stress without significantly impairing flexibiUty. FiaaHy, effectively located restraints can reduce thermal effects on the equipment. 

Acceptable comprehensive methods of analysis are analytical, model-test, and chart methods, which evaluate for the entire piping system under consideration the forces, moments, and stresses caused by bending and torsion from a simultaneous consideration of terminal and intermediate restraints to thermal expansion and include all external movements transmitted under thermal change to the piping by its terminal and intermediate attachments. Correction factors, as provided by the details of these rules, must be applied for the stress intensification of curved pipe and branch connections and may be applied for the increased flexibihty of such component parts. 

Paper [16] reported unusual behaviour of the widths of rotational components of the P-R doublet of HC1 dissolved in SFg. They decreased with increasing temperature. The widths of spectral lines, obtained with (7.73), really must decrease with increasing temperature, because tc decreases due to intensification of thermal motion, and V[ due to thermal expansion. 

Wegeng, R. S., Drost, M. K., Brenchley, D. L., Process intensification through miniaturization of chemical and thermal systems in the 21. century, in Ehreeld, W. (Ed.), Microreaction Technology 3rd International Conference on Microreaction Technology, Proc. of IMRET 3, pp. 2-13, Springer-Verlag, Berlin (2000). 

Fig. 7. Process intensification and adverse thermal destruction effects of the aqueous Kolbe-Schmitt synthesis of phloroglucinol using high-p,T processing. (Courtesy of Wiley-VCH)...

Intensified trades at the same season are associated with equatorial divergence upwelling east of 10°W, and intensification of the Guinea, Angola, and the Costa Rica thermal domes. ... 

If an atomic transition is optically pumped by a beam of laser radiation having the appropriate frequency, the population in the upper state can be considerably enhanced along the path of the beam. This causes an intensification of the spontaneous emission from this state, which contains information about the conditions within the pumped region, since the exponential decay time for the intensified emission depends upon both the electron number density and the electron temperature. The latter can be obtained from the intensity ratio of the fluorescence excited from two different lower levels, if local thermal equilibrium is assumed. This method has been dis-... 

This last quantity is of particular interest for thermal engineering since we determine the upper intensification limit of fuel-burning devices depending on the chemical reaction rate. Barskii and Zeldovich determined this quantity for a number of carbon monoxide mixtures the heat release rate exceeds 109kcal/hr m3. For purposes of comparison we note that in present-day industrial furnaces and reactors, the heat release rate taken with respect to the entire volume of the furnace wavers between 2 105 and 5 106 kcal/hr-m3. 

The terms intensification and low capacity introduced above are related to the expression for the thermal loading of a unit of volume... 

Thonon B, Mercier P. Flow structure, thermal and hydraulic performances of compact geometries used as integrated heat exchanger reactor. Process Intensification Conference, Antwerp, October 1999. 

Phillips CH, Lauschke G, Peerhossaini H. Intensification of batch processes using integrated chemical reactors-heat exchangers. Appl Thermal Eng 1997 17(8.10) 809-824. 

Acidification. The acidification and thermal pollution impacts of a chemical plant in general do not come from the plant itself but are related to the conversion of fossil fuel to energy (steam, electricity) hence the same emission reduction factor as for carbon dioxide is assumed for the process intensification potential. 

Meltser, V. I., Luboshitz, A. I. and Smagina, T. V. (1986). Drying of thermo labile material in reversed jets. Intensification of Thermal Drying Processes, Collection of the Science Transactions, Minsk, ITMO AN BSSR, 62-70 (in Russ). 

The next important step in the elucidation of the role of the thermal factor in the mechanism of the phenomena in question was studying the effect of the sample size on the characteristics of the autowave process. Can the self-sustained wave regime of conversion be made impossible by intensification of heat release at the expense of a decrease in the diameter of a cylindrical sample containing the reactant mixtures By analogy with combustion physics, the question of a critical sample size has been raised. 

El. Elperin, I. T., Zabdrodsky, S. S., and Mikhailik, V. D., Collected Papers on Intensification of Transfer of Heat and Mass in Drying and Thermal Processes, p. 232. Nauka i Tekhnika, B3SR, 1967. 

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