Chemical Furnaces Research Articles

A Probabilistic Statistical Method for the Determination of Void Morphology with CFD-DEM Approach

Voids that are formed by gas injection in a packed bed play an important role in metallurgical and chemical furnaces. Herein, two-phase gas–solid flow in a two-dimensional packed bed during blast injection was simulated numerically. The results indicate that the void stability was dynamic, and the void shape and size fluctuated within a certain range. To determine the void morphology quantitatively, a probabilistic method was proposed. By statistically analyzing the white probability of each pixel in binary images at multiple times, the void boundaries that correspond to different probability ranges were obtained. The boundary that was most appropriate with the simulation result was selected and defined as the well-matched void boundary. Based on this method, the morphologies of voids that formed at different gas velocities were simulated and compared. The method can help us to express the morphological characteristics of the dynamically stable voids in a numerical simulation.

Structure and phase formation of combustion products during the synthesis of γ-AlON in self-propagating high-temperature synthesis

Synthesis of aluminum oxynitride (γ-AlON) in conditions of self-propagating high-temperature synthesis (SHS) gas-statting under high pressures (10–100 MPa) of gaseous nitrogen, including the mode of so-called coupled combustion reactions (chemical furnaces) is investigated. It is shown that chemical and phase compositions of combustion products, as well as their structure and morphology of powder particles, depend on the reagent ratio in Al–Al2O3 initial mixture, as well as on nitrogen pressure, combustion temperature of highly exothermic components of chemical furnaces, and grade of initial reagents. The structure of γ-AlON powder particles are determind and its relation with operation conditions of SHS. Optimal SHS parameters for Al5O6N (γ-AlON) formation are established.

Nanostructured particles of boron, aluminum, and silicon nitrides by thermally coupled SHS reactions of nitriding

The paper shows the investigation results of structure and phase formation of boron, aluminum and silicon nitride particles in gaseous nitrogen of high pressure (10–40 MPa) under the terms of thermocoupled high- and low-exothermic reactions (so-called chemical furnaces). In this case the high-exothermic reaction is an additional heat source for the low-exothermic one. The reactions are separated in space and chemically independent. The nitriding terms which are close to extreme ones (high burning temperatures of aluminum, boron and silicon, high heating rates, etc.) provide the reagent evaporation and promote gastransport reactions with the combustion mechanism transition from the solid-phase to gas-phase or vaporliquid due to volatile intermediate products of nitriding and impurities. As a result, the SHS products contain not only well-known forms of nitride particles (nano-fibers, nano-filaments, nano-plates, nano-whiskers, etc.) but such structures as BN nano-tubes with various types of morphology and cubic modifications of BN and AlN as well. It is to be studied additionally.

STRUCTURE AND PHASE FORMATION OF COMBUSTION PRODUCTS DURING Γ-ALON SYNTHESIS IN SHS GAS-STATTING MODE

The paper studies synthesis of aluminum oxynitride (γ-AlON) under the conditions of SHS gas-statting at high pressures (10–100 MPa) of gaseous nitrogen including the mode of so-called conjoint combustion reactions (chemical furnaces). It was shown that chemical and phase compositions of combustion products, their structure and morphology of powder particles depend on the reagent ratio in the initial Al–Al 2 O 3 mixture, as well as nitrogen pressure, combustion temperature of high-exothermic components of chemical furnaces, and type of initial reagents. The structure of γ-AlON powder particles was studied and its relation to self-propagating high-temperature synthesis conditions was found. It determines the optimum SHS parameters for Al 5 O 6 N (γ-AlON) synthesis.

Making Instruments Count: Essays on Historical Scientific Instruments Presented to Gerard L’Estrange Turner ed. by R. G. W. Anderson

TECHNOLOGY AND CULTURE Book Reviews 201 Making Instruments Count: Essays on Historical Scientific Instruments Pre­ sented to Gerard LEstrange Turner. Edited by R. G. W. Anderson, J. A. Bennett, and W. F. Ryan. Brookfield, Vt.: Variorum (Ashgate), 1993. Pp. xix+492; illustrations, notes, index. $89.95. This book is a festschrift in honor of Gerard L’Estrange Turner, undoubtedly a most influential figure in the history of scientific instru­ ments over the last generation. This influence has been effected through twelve books, more than 100 articles, numerous biographical articles, and, less obviously, his editorship of thejournal Annals ofScience. A useful list of his publications appears in the book’s preface. The thirty-five articles in this volume cover a wide range ofissues and, predictably, vary in depth of analysis. Some provide the merest description of an instrument or a chronology of development. Others suggest entirely new questions about the use of instruments in science and their interpretation by historians or explore the dynamics of the instrument trade. The two opening essays, byJ. L. Heilbron and A. J. Turner, are among the most stimulating on broader historiographic questions. Heilbron assures us that instrument catalogs have functioned to standardize phenomena perhaps even more than the instruments themselves. More generally, he advocates historical study of the “rhetoric of scientific instruments.” Turner points out that it is important for historians to show how instruments were important to the science of their time and not just to assert that they were. At a deeper level, he notes the anachronism of the very term “scientific instrument.” He endorses Derek Price’s point that instruments have been used for measurement and to provide the raw material for theory construction but also for revelation and out of a “sheer love of machinery.” Turner, however, qualifies this endorsement via a long discussion of types of instruments and periods in their development. While these schema are not without objection, this essay should be required reading for anyone writing the history of instruments. Many of the articles concern some particular class of instrument or even an individual instrument: an astrolabe from Picardy, astronomical paper instruments, 18th-century chemical furnaces, or Charles Wheat­ stone’s wave machine. Some of these are most suggestive; some are not. A. D. C. Simpson’s discussion of 19th-century British pendula is a careful and detailed account that transcends the instrument itself to explore its roles in sanctioned metrology and in the study of the earth. Of special interest to historians of technology with no special penchant for scientific instruments is Willem Hackmann’s discussion and catalog of W. G. Armstrong’s hydroelectric machines, which used a steam boiler to generate static electric charges. Hackmann relates the machine to its actual contexts: the popular interest in electricity in early Victorian Britain and the relations of science to light industry. Moreover, he provides period illustrations and photographs of surviving machines. 202 Book Reviews TECHNOLOGY AND CULTURE Instruments in various institutional contexts are also treated. J. A. Bennett examines the interactions of Thomas Hornsby at the Radcliffe Observatory, Oxford, with his instrument makers; Marijn van Hoorn relates the development of the instrumentation at the Teyler’s physical laboratory in Haarlem, Holland; and J. C. Deiman discusses Utrecht University’s microscopes. Several articles provide windows on the instrument-making trade. The instrument makers John Bird, George Graham, and Jesse Ramsden (among others) figure prominently in Bennett’s article. Gloria C. Clifton provides a careful social and institu­ tional analysis of the producers of optical instruments in 17th- and early18th -century London, complete with a list of all the known manufac­ turers for this period. There are also detailed examinations ofindividual instrument makers and their businesses or achievements: Hemming Andersen on the Dane Jeppe Smith, Allan Chapman on Jesse Ramsden as a figure who “scaled up” instrument making to an industrial level, and Anita McConnell on the use of Thomas Cooke’s order book to get at a social analysis of who the buyers were for optical instruments circa 1860. Making instruments count, in the history of technology or in the history of science, is no easy matter. Still needed are more catalogs, more photographs and other illustrations, and more...

Study on Low NOx Burners for Chemical Furnaces

As a result of study on the NOx formation choracteristics of pre-mixed flames, we have succeeded in developing new low NOx berners. These burners can be used for various kinds of chemical furnaces as gas and/or oil firing burners with a natural draft system.According to the results of test of these burners in the semicommercialized scale test furnace, their NOx emissions were very small, being 30 ppm in propane or naphtha firing, 45 ppm in A heavy oil firing and 90 ppm in C heavy oil firing (of the time of combustion of 5% excess O2)

Chemical furnaces of ancient Mesopotamia and Palestine

That the ancient Mesopotamians and Palestinians attained a marked craftsmanship and extensive chemical technology is known from the artifacts of their civilization; the furnaces used by these early chemists is described to facilitate our understanding of their technological achievements.

Shaking Type Corrosion Tester for Refactory Brick

The new type of refractory corrosion tester was made by authors and tried to operate for various bricks with various slags The small furnace (inner capacity 110×110×50mm), contained 500-1000 grams of molten slag with 5-10 mms layer was shaken on the 4 rollers 25 times per minute with maximum inclined degrees of 20° being heated at about up to 1600°C, then in these conditions the small brick specimens were seriously corroded as groove. The corrosion depths measured within the error of 1mm were sufficient to indicate the differences of corrosion resistance of various bricks. Although such a tester has the very small type, it is not only providing to us much informations of using brick to a large furnace, but we can use this tester to study on the various other phenomena which would happen in actual metallurgical and chemical industrial furnaces.