Gas-Condensate Reservoir Pseudo-relative Permeability Derived by Pressure-Transient Analysis. Incorporation of Near-Wellbore Effects

Gas-condensate reservoirs exhibit a near-wellbore complex behavior due to the existence of a two-phase system when pressure drops below dew point. In analyzing well-testing data, a single-phase approach is only valid for well condition above dew point, whereas a multi-phase pseudo-pressure approach is widely adopted for a gas reservoir operating below dew-point. This article utilizes the pseudo-pressure approach, for analyzing well-test data in gas-condensate reservoirs producing below the dew-point pressure, to generate Corey exponents for relative permeability in order to determine near-wellbore representative relative permeability that history matches the actual well-testing data.     

Correlations in the properties of Albanian coals

Seventeen Albanian brown coals were analyzed in detail and their properties were compared on both a national and regional basis. The measurements made were moisture, proximate and ultimate analyses, sulfur forms, bituminous matter, humic acids and specific energy, plus Gray-King and free-swelling tests. Linear correlations were derived amongst these coal properties on both dry and dry-ash-free basis. The resulting equations would allow the prediction of many coal properties from a limited number of experimental measurements.     

Development of a portable spectrofluorimeter for measuring the microbial spoilage of minced beef

The evaluation of meat spoilage is based on sensory and microbiological analyses. The disadvantages of sensory analyses are its reliance on highly trained panelists, a procedure which makes it costly and unattractive for routine analyses. Moreover, the classical microbiological analyses are lengthy, costly and destructive. In this study a portable fluorescence spectrometer was tested to quantify minced beef spoilage. This study was investigated on samples stored aerobically and under vacuum at 5 and 15 °C. Total viable counts (TVC), Pseudomonas, lactic acid bacteria, and yeast/molds counts were investigated with classical culture methods. Fluorescence spectra were recorded on the same samples using different excitation LEDs (280, 320, and 380 nm). PLS-R with leave-one-out cross validation was used to perform calibration and validation models. The PLS-R models presented good R2(CV) (0.50-0.99) and ratio of standard deviation (RPD(CV): 1.40-8.95) values after cross-validation. It could be concluded that portable spectrofluorimeters are promising devices to evaluate spoilage in minced beef.     

Structural changes of milk components during acid-induced coagulation kinetics as studied by synchronous fluorescence and mid-infrared spectroscopy

Dynamic oscillatory experiments and front-face synchronous fluorescence spectroscopy and mid-infrared (mid-IR) spectroscopy have been used to investigate structure evolution, at the macroscopic and molecular levels, during milk acidification kinetics. The studies were performed using skim milk, at two different temperatures (30 °C and 40 °C), to which was added glucono-δ-lactone (GDL) to generate different structural changes in casein micelles and gels. Synchronous fluorescence spectra were recorded in the 250-500 nm excitation wavelength range using an offset of 80 nm between the excitation and emission monochromators for each system during the 300 min acidification kinetics. The change in the fluorescence intensity at 281 nm reflects the pH-induced physicochemical changes of casein micelles and, in particular, structural changes in the micelles in the pH range 5.5-5.0. Regarding mid-infrared spectroscopy, the region located between 1700 and 1500 cm(-1), corresponding to the amide I and II bands, and the 1500-900 cm(-1) region, called the fingerprint region, were considered for the characterization of milk coagulation kinetics. Changes in the absorbance at 1063 cm(-1) as a function of pH for kinetics recorded at 30 °C and 40 °C reflected pH-induced phosphate dissolution in the pH range 5.5-5.0. Compared to rheometry, which reveals microstructure changes only in the gel state, spectroscopic methods make it possible to monitor molecular structure changes in micelles throughout the acidification processes.     

Correlation between ash fusion temperatures and chemical composition in Albanian coal ashes

This paper presents an analysis of the ash fusion temperatures (AFTs) for 17 Albanian coals. The contribution of oxides to AFTs is investigated by considering oxides from various perspectives: as discrete species, acids and bases, crystal components, fluxing agents, and cement constituents, and in accordance with the periodic table. Empirical correlations use simple and multiple linear equations and polynomial equations, referring to both weight and molar percentages. The shift from the deformation temperature to the flow temperature is accompanied by a shift of influence from basic oxides to acidic oxides. Many predictive correlative equations are obtained.     

Evaluation of the effects of acetyl tributyl citrate as bio‐based plasticizer on the physical,thermal, and dynamical mechanical properties of poly(vinyl chloride)/polymethyl methacrylate blends

This article details our work in studying the plasticization of Poly(vinyl chloride) (PVC)/Polymethyl methacrylate (PMMA) blends with bio‐based acetyl tributyl citrate (ATBC) in place of conventional plasticizers such as di(2‐ethylhexyl) phthalate. PMMA was blended with PVC in various ratios from 0 to 100 wt% by melt compounding with or without the plasticizer ATBC. Both the glass transition temperatures of the blends (differential scanning calorimetry) and Tα (dynamic mechanical thermal analysis) are consistent with a miscibility of the components, and Fourier transforms infrared spectroscopy studies show that there are specific interactions in the PVC/PMMA blends favoring the miscibility. The thermal degradation of the blends was studied by thermogravimetric analysis that shows the thermal degradation of rigid and plasticized PVC/PMMA is a process composed of two‐steps and that PMMA exercises a stabilizing effect on the thermal degradation of PVC during the first step by decreasing the rate of dehydrochlorination. J. VINYL ADDIT. TECHNOL., 25:E73–E82, 2019. © 2018 Society of Plastics Engineers     

Correction of pressure drop in a heavily loaded hybrid bearing when starting by using a constant flow lubrication system- Application to a rotary cement mill

We analyzed a lubricated journal plain bearing supporting heavy loaded rotary mill. During start-up operating, after the shaft is lifted by high external pressure lubricant, the speed of the shaft grows from 0 to the operating hydrodynamic speed when, suddenly after the first thirty seconds of shaft rotation, the pressure drops in one recess causing excessive damage to the pad bearing interface. The aim was to understand and provide some answers to the pressure drop in order to give an appropriate correction. Misalignment between the shaft and bearing surfaces was considered and analyzed in first part of the study. According to the obtained results the proposed correction is to use a suitable constant flow lubrication system which avoids the pressure to drop in recesses. A real application was made on a partial pad bearing supporting a heavy rotary cement mill localized at the cement plant of Chlef in Algeria.

     

Heterogeneous Catalytic Polymerization of Ethylene in Microtubular Reactor Systems

The feasibility of using a microtubular reactor for heterogeneous polymerization of ethylene was investigated experimentally. Chemically inert polymer tubing of 800–2300 μm in inner diameter was fabricated and used as a polymerization reactor. Nonporous silica nanoparticles with a diameter of 400 nm were synthesized and used as support for the high‐activity rac‐ethylene(indenyl)₂ZrCl₂ catalyst with methylaluminoxane as cocatalyst and toluene as diluent. Large‐diameter microtubular reactors were also successfully used to conduct heterogeneous polymerization of ethylene in continuous reaction operations. High initial catalyst activity was obtained and the overall polymerization activity per volume or reactor length was quite high. No particle fragmentation occurred and the polymer particles were covered with small subgrains or nanofibrils with a diameter of 30 nm.