ASPHALTENE AND RESID PYROLYSIS: EFFECT OF REACTION ENVIRONMENT

ABSTRACT

Hondo and Maya vacuum resids and their isolated asphaltenes were pyrolyzed at 400, 425, and 450^°C (752, 797, 842^°F) for batch holding limes ranging from 20 to 180 minutes. Maltene, asphaltene, and coke product fractions were isolated by a solvent extraction sequence; gas yield was determined gravimetrically. Results were summarized in terms of a lumped reaction network. The variation of product yields, kinetics, and apparent activation energies with feedstock and asphaltene environment provided insight into asphaltene structure and thermal reaction pathways.     

Methods for solving the stochastic point reactor kinetic equations

In this paper we present two new methods to analyze the statistical properties of nonlinear outputs of a point reactor to stochastic non-white reactivity inputs. They are Bourret's approximation and logarithmic linearization. The results have been compared with the exact results, previously obtained in the case of Gaussian white reactivity input. It was found that when the reactivity noise has short correlation time, Bourret's approximation should be recommended because it yields results superior to those yielded by logarithmic linearization. When the correlation time is long, Bourret's approximation is not valid, but in that case, if one can assume the reactivity noise to be Gaussian, one may use the logarithmic linearization.     

The effects of fatty acids on the particle size distribution of the Portland cement

The cement has to be ground fine enough and have the optimum particle size distribution (PSD) to meet the requirements such as strength properties and setting times in current standards. As it takes quite a long time to determine especially the late strength, grinding has to be based on the cement fineness and the PSD. In this study, the effects of fatty acids were investigated on the PSD of Portland cement. Experimental results showed that the fineness of the cement was decreased for that replaced with 0.025 wt.% lauric acid (LA), myristic acid (MA) and sunflower oil acid (SO), then increased for the other additions. The fineness measurements revealed that the cement grains aggregated for an amount of 0.025 % (w) during the grinding. Also, when the PSD of the ground cement is examined, the relationship between the saturated and the unsaturated components is evident that milling the cement clinker together with 0.1% (w) LA and 0.1 wt. % MA gave the finer cement from that with 0.1 wt.% SO.     

热轧带钢卷取机的卷取过程研究及发展

对热轧带钢卷取机进行了试验研究,分析了卷取良好卷形的机理,将现代热轧带钢卷取机的发展划分为三代,并作了对比,对卷取机的引进与改造提出了参考意见。     

A reconnaissance report: 1995 Dinar, Turkey, earthquake

During the 1st October 1995 Dinar, Turkey, earthquake, a total of 90 people died and about 240 people were injured. The number of collapsed or heavily damaged buildings exceeded 8000 within a radius of 20 km around the epicentre. The ground rupture was about 11 km long along an unexpected, new fault line. The reinforced concrete moment resisting framed structures as well as brick masonry houses experienced the most severe damage, especially those situated on soft soil layers of alluvium formations.     

A hybrid tracking method for scaled and oriented objects in crowded scenes

Traditional kernel based means shift assumes constancy of the object scale and orientation during the course of tracking and uses a symmetric/asymmetric kernel, such as a circle or an ellipse for target representation. In a tracking scenario, it is not uncommon to observe objects with complex shapes whose scale and orientation constantly change due to the camera and object motions. In this paper, we propose a multi object tracking method which tracks the complete object regions, adapts to changing scale and orientation, and assigns consistent labels to each object throughout real world video sequences. Our approach has five major components: (1) dynamic background subtraction, (2) level sets, (3) mean shift convergence, (4) object identification, and (5) occlusion handling. The experimental results show that the proposed method is superior to the traditional mean shift tracking in the following aspects: (1) it provides consistent multi objects tracking instead of single object throughout the video, (2) it is not affected by the scale and orientation changes of the tracked objects, (3) its computational complexity is much less than traditional mean shift due to using level set method instead of probability density.     

Model predictive force control in milling based on an ensemble Kalman filter

Journal of Intelligent Manufacturing - Process force determines productivity, quality, and safety in milling. Current approaches of process design often focus on a priori optimization. In...     

Phenolic resin binder for the production of metallurgical quality briquettes from coke breeze: Part I

Phenol based novalac, resol and the blend of both resins were used as binders in briquette production from coke breeze. The effects of the amount of catalyst on the tensile strength of the cured briquette were studied. The results obtained have indicated that the highest tensile strength could not be attained unless the blend of novalac and resol was used as binder. The most suitable blend was the binder prepared from the hydrochloric acid catalyzed novalac of F/P = 0.5 and the N/P = 0.3 catalyzed resol of F/P = 2.0. When this blend was used as a binder the tensile strength of the cured briquettes did not drop even if they were carbonized at 470 °C and 570 °C. Their strengths at these carbonization temperatures were 67 MPa and 72 MPa respectively, and the rise in the temperature resulted in some increase in their strength. These results show the fact that as the formed coke briquettes descends from the top of the blast furnace, the rise in temperature will not deteriorate their strength; it will probably improve their properties. Therefore, only curing at 200 °C for 2 h will be sufficient for the briquettes to be used as substitute for metallurgical coke in the blast furnace.     

Preparation, GIAO NMR Calculations and Acidic Properties of Some Novel 4,5-dihydro-1H-1,2,4-triazol-5-one Derivatives with Their Antioxidant Activities

Six novel 3-alkyl(aryl)-4-(p-nitrobenzoylamino)-4,5-dihydro-1H-1,2,4-triazol-5- ones (2a-f) were synthesized by the reactions of 3-alkyl(aryl)-4-amino-4,5-dihydro-1H- 1,2,4-triazol-5-ones (1a-f) with p-nitrobenzoyl chloride and characterized by elemental analyses and IR, ¹H-NMR, ¹³C-NMR and UV spectral data. The newly synthesized compounds 2 were titrated potentiometrically with tetrabutylammonium hydroxide in four non-aqueous solvents such as acetone, isopropyl alcohol, tert-butyl alcohol and N,N-dimethylformamide, and the half-neutralization potential values and the corresponding pK_a values were determined for all cases. Thus, the effects of solvents and molecular structure upon acidity were investigated. In addition, isotropic ¹H and ¹³C nuclear magnetic shielding constants of compounds 2 were obtained by the gauge-including-atomic-orbital (GIAO) method at the B3LYP density functional level. The geometry of each compound has been optimized using the 6-311G basis set. Theoretical values were compared to the experimental data. Furthermore, these new compounds and five recently reported 3-alkyl-4-(2-furoylamino)-4,5-dihydro-1H-1,2,4-triazol-5-ones (3a–c,e,f) were screened for their antioxidant activities.     

Formate ion decomposition in water under UV irradiation at 253.7 nm

Formate ion (HCO2-) occurs in natural waters as a result of photooxidation of humic substances. Under UV irradiation, as applied in water purification (253.7 nm), formate ion decomposed following split-rate pseudo-zero-order kinetics (k1 and k2 are initial and final rate constants, respectively). In the presence of dissolved oxygen (DO), it was found that (a) k1 < k2, (b) k1 and k2 increased with initial formate ion concentration ([HCO2-]0 = (1.73-38.3) x 10(-5) mol L(-1)) and absorbed UV intensity (Ia = (1.38-3.99) x 10(-6) mol quanta L(-1) s(-1)), and (c) k1 and k2 were relatively insensitive to initial pH (pHo = 5.41-8.97) in buffer-free solutions. Both rate constants decreased with increasing carbonate alkalinity ((0-1.0) x 10(-3) mol L(-1)) and k1 was virtually unchanged in phosphate buffer at pH0 between 5.25 and 9.92. Carbonate buffer lowered the rate of formate ion decay, possibly due to scavenging of OH* radicals. Initial rate constant k1 slightly increased with temperature (15-35 degrees C), while k2 remained unchanged. The reaction pH increased rapidly during irradiation of buffer-free NaHCO2 solution to approach an equilibrium level as [HCO2-] reached the method detection level (MDL). The pH profile of buffer-free formate ion decay was estimated using closed-system equilibrium analysis. DO utilization during UV irradiation was 0.5 mol of O2/mol of HCO2-, while nonpurgeable organic carbon (NPOC) measurements on kinetic samples closely followed the HCO2- profile, thus strongly suggesting the transformation of HCO2- -C to CO2 in the presence of DO. In DO-free water, k1 > k2 was observed. Furthermore, k(1,DO FREE) > k(1,DO) (k(1,DO) = k1) and k(2,DO FREE) < k(2,DO) (k(2,DO) = k2). The effect of dual acid solutions on HCO2- decay was examined in a mixture of NaHCO2 and sodium oxalate (Na2C2O4). HCO2- decomposed readily until [HCO2-] approximately equal to MDL but at a lower rate than in buffer-free HCO2- solutions, while C2O4(2-) remained virtually unchanged. C2O4(2-) decay commenced following near complete conversion of HCO2-.