The Production of Electrical and Thermal Energy from the Exhaust Gas Heat of Preheater Kilns

It is shown, by means of an example, i.e., a 1600-ton/day four-stage suspension preheater kiln of a cement factory, that the waste heat present in the exhaust gases can be converted into useful electrical and thermal energy. This is possible even though the exhaust gases are heavily loaded with dust. The heat recovery system installed in 1981/1982 in a Swiss cement plant and the respective production line are described in detail. A comprehensive explanation is given concerning the experience of the first operating year, the iqteraction of the new plant with the existing production facilities, and the current measured technical data. The performance limits for economic operation are explained and the decision criteria quoted. Further applications of the successfully tested heat recovery system can be expected wherever beat sources in the form of heavily loaded gases are available.     

Maillard reactions of dextrins and starch

When dextrins or starch are heated with propyl-amine in neutral aqueous solution at 100–130° C a brown colouration is observed. From the reaction mixture 3-hydroxy-2-methyl-1-propyl-4(1H)-pyridone11, 1,4-dihy-dro-2-methyl-1-propyl-4-propylimino-3-pyridinol12 and 5-hydroxymethyl-1-propyl-pyrrol-2-aldehyde13 can be extracted with organic solvents and separated by HPLC. Enzymatic hydrolysis effects the release of 1(3-hydroxy-1-propyl-2-pyrrolyl)-1-ethanone10 from a glycosidically bound precursor.

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Maillard Reaktionen von Dextrinen und Stärke

Zusammenfassung Erhitzt man Dextrine oder Stärke mit Propylamin in neutraler wäßriger Lösung auf 100–130 °C, so beobachtet man eine braune Färbung. Aus der Reaktionsmischung lassen sich 3-Hydroxy-2-methyl-1-propyl-4(1H)-pyridon11, 1,4-Dihydro-2-methyl-1-pro-pyl-4-propylimino-3-pyridinol12 und 5-Hydroxymethyl-1-propyl-pyrrol-2-aldehyd13 mit organischen Lösungsmitteln extrahieren und durch HPLC trennen. Nach enzymatischer Hydrolyse der wasserlöslichen Fraktion ist 1(3-Hydroxy-1-propyl-2-pyrrolyl)-1-ethanon10 isolierbar.

     

Teaching preschool children with disabilities to respond to the lures of strangers

An investigation was conducted to determine the effectiveness of a constant-time-delay procedure used in combination with multiple exemplars of strangers, lures, and sites to teach a generalized response to the lures of strangers to four preschool children with disabilities. Although the correct response was quickly acquired in the training site, the response failed to generalize to the probe sites until training was conducted in vivo. Instruction in vivo resulted in acquisition, maintenance, and generalization of the response to strangers' lures. Generalization occurred across probes with novel exemplars of lures, strangers, and sites.     

Untersuchungen zur Maillard-Reaktion XX. Nachweis von Glycerinaldehyd, Dihydroxyaceton und anderen hydrophilen Zuckerabbauprodukten in Caramellisierungsgemischen

Zusammenfassung Zuckerabbauprodukte lassen sich durch Umsetzung mit O-Methylhydroxylamin und anschließende Acetylierung zu gaschromatographisch gut trennbaren Verbindungen umsetzen. In Zucker-caramellisierungsgemischen konnten so Glycerinaldehyd, Dihydroxyaceton, Erythrose, 3-Deoxyhexosulose und Methylglyoxal nachgewiesen werden. Auch in der Kruste von Brezen entstehen Glycerinaldehyd und Dihydroxyaceton.

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Investigations relating to the maillard reaction XX. Identification of glyceraldehyd dihydroxyacetone and other hydrophilic sugar degradation products in caramel mixtures

Summary Sugar degradation products can be determined by g.l.c. after reaction with O-Methylhydroxylamine and subsequent acetylation. Thus dihydroxyacetone, glyceraldehyde, erythrose, 3-deoxyhexosulose and methylglyoxale have been detected in caramelisation mixtures. Dihydroxy-acetone and glyceraldehyde could also be identified in the crust of a special bakery product.

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XIX. Mitteilung: Ledl F, Hiebl J, Severin Th (1983) 177:353–355     

Accuracy of the finite element method near a curved boundary

Solutions of problems by the finite element method, when curved boundaries are present in the model, may not be accurate. Such a difficulty arises when straight-line elements are used to approximate the curved boundary. This behavior is known in the literature as the “Babuska Paradox”. Despite the fact that the problem has been recognized since the mid 60's, and methods to overcome it have been used quite successfully, many textbooks still ignore it. Here, this “paradox” is demonstrated by plane-stress problems, to which analytical results exist. One known method (the isoparametric element) is used to show how to overcome these difficulties.     

Bildung von Benzaldehyd aus Phenylalanin und N-Acetylphenyl?thylamin beim Erhitzen unter Einwirkung von Luft

Zusammenfassung Erhitzt man Phenylalanin, N-Acetylphenyläthylamin oder N-Glycyl-phenylalanin alleine oder mit Triglyzeriden in Gegenwart von Luft auf Temperaturen um 190–200° C, so wird Benzaldehyd gebildet.

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Formation of benzaldehyde from phenylalanine and phenylethylamine by heating under air blast

Summary Benzaldehyde is formed when phenylalanine, n-acetyl-phenylethylamine or n-glycyl-phenylalanine alone or with triglycerides in presence of air are heated to a temperature of nearly 190–200° C.

     

Reactions of unsaturated fatty alcohols. VI. Guerbet reaction of soybean and linseed alcohols

Summary Both soybean and linseed alcohols were heated with potassium hydroxide and boric anhydride at 300°C. for 3 to 4 hrs. Products obtained under these conditions contained no unreacted starting alcohol, and each one appeared to be a mixture of condensed alcohols with average molecular weights of 720–860. Infrared spectroscopic studies and chemical analyses indicate that little or no ethers, esters, or carbonyl compounds were present in the final product from either alcohol. Such reactions as thermal cross-linking of the unsaturated side chains probably account for higher molecular weight products than those obtained in the Guerbet reaction of stearyl alcohol. Condensed alcohols from soybean and linseed alcohol were esterified with acrylic, sorbic, maleic, and soybean fatty acids to yield products with low acid numbers. Preliminary experiments demonstrated that these alcohols and their esters showed promise as materials for protective coatings. Films from these alcohols and esters were cast from toluene containing a cobalt naphthenate drier and were baked at 150°C. for 1 hr. or at 200°C. for 20 min. All of the baked films were hard to moderately hard and showed good resistance to aqueous alkali and organic solvents. In general, films from soybean condensed alcohol and its esters were harder than those from linseed condensed alcohols, but the linseed films were superior in alkali and solvent resistance. A soybean fatty acid ester of soybean condensed alcohol air-dried to a soft film in 3 days. Presented at the 49th Annual Meeting, American Oil Chemists' Society, April 21–23, 1958, Memphis, Tenn.