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Hydrogen-Bonded organic frameworks (HOFs) are a type of emerging porous materials. At present, little research has been conducted on their solution state. This work demonstrates that HOFs fragment into small particles while maintaining their original assemblies upon dispersing in solvents, as confirmed by Cryo-electron microscopy coupled with 3D electron diffraction technology. 1D and 2D-Nuclear Magnetic Resonance (NMR) and zeta potential analyses indicate the HOF-based colloid solution and the isolated molecular solution have significant differences in intermolecular interactions and aggregation behavior. Such unique solution processibility allows for fabricating diverse continuous HOF membranes with high crystallinity and porosity through solution-casting approach on various substrates. Among them, HOF-BTB@AAO membranes show high C3H6 permeance (1.979 × 10−7 mol·s−1·m−2·Pa−1) and excellent separation performance toward C3H6 and C3H8 (SF = 14). This continuous membrane presents a green, low-cost, and efficient separation technology with potential applications in petroleum cracking and purification. Hydrogen-bonded organic frameworks (HOFs) attract increasing attention as porous materials. Despite the widely studied solid-state properties, little research has been done on the solution state. Here, the authors demonstrate that HOFs fragment into small particles while maintaining their original assemblies upon dispersing in solvents. [ABSTRACT FROM AUTHOR]

Flexible strain sensors are capable to detect external force induced strain change owing to their unique ability to convert deformation into electrical signals. Generally, micro/nano patterning of conductive layer in strain sensor is an effective method to improve its sensitivity, however the sophisticated manipulation process is limited only in laboratory scale. In this report, a simple and scalable fabrication strategy was used to create micro-cracking conductive layer as an alternative patterning method to achieve high performance of strain sensor. In details, the sensor was fabricated using leather as the substrate to filtrated acidified multi-walled carbon nanotubes (a-MWCNTs)/layered double hydroxides (LDHs) suspension. During stretching process, micro-cracking structure emerged on the percolated a-MWCNTs/LDHs layer, causing a rise up of resistance according to increasing strain and generated a detectable electrical signal. The prepared sensor had a large detecting range (60%), high sensitivity (GF of 7238.92 at strain 30–60%), fast response (tensile response time of 270 ms), good stability and repeatability. The sensor also inherited the advantages of leather, such as biodegradability and good air permeability, and the introduction of a-MWCNTs/LDHs further enhanced its fire retardancy properties. These features ensured the sensor as an eco-friendly, comfortable and safe electronic device for human motion detection. [ABSTRACT FROM AUTHOR]

To improve the catalytic activity of zeolites in cracking of petroleum components for the production of light olefins, ZSM-5–USY composite catalysts modified with transition metals (e.g. Nb, Ni, or W) have been synthesized by an impregnation method. The catalytic performance of the obtained catalysts in the cracking of n-hexane as a model compound of petroleum for the production of light olefins has been evaluated using a fix-bed reactor. The Nb-modified composite zeolite has shown an excellent catalytic activity. The optimal Nb loading for the composite catalyst is 1.5% (1.5% Nb/Z–Y) that provides the highest amount of acid sites. The yield up to 50% and the selectivity up to 68% of the C2–C4 olefins have been achieved at 650°C. The kinetic study of the catalytic n-hexane cracking on 1.5% Nb/ZSM-5–USY has characterized it as the first-order reaction with the apparent activation energy of 115.16 kJ/mol. [ABSTRACT FROM AUTHOR]

Y Zeolite plays an irreplaceable role in many important applications due to its unique physicochemical properties, which has attracted extensive attention from researchers. Response surface methodology (RSM) was used to optimize the process parameters for the hydrothermal synthesis of Y zeolite using kaolin activated by microwave heating. The best relative crystallinity was 108.17% could be achieved at the condition: the aging temperature of guiding agent was 65 ℃, the crystallization temperature was 100 ℃, the crystallization time was 24 h. In addition, the aging temperature of guiding agent was the most important influence factor. Under the optimal condition, the SiO2/Al2O3 ratio of synthesized Y zeolite was 4.54, 90% of the particle size was less than 60 μm, and the specific surface area of Y zeolite was 479 m2/g. The successful preparation of Y zeolite with high crystallinity is expected to provide reference for the application of wastewater treatment, CO2 sequestration and fluid catalytic cracking for petroleum. [ABSTRACT FROM AUTHOR]

Hot tearing is one of the most serious defects during the casting solidification process. In this study, a new type of multichannel "cross" hot tearing device was designed. The hot cracks initiation and propagation were predicted by the relationship between temperature, shrinkage force and solidification time during the casting solidification process. The reliability and practicability of the multichannel "cross" hot tearing device were verified by casting experiments and numerical simulations. The theoretical calculation based on Clyne-Davies model and numerical simulation results show that the hot tearing tendency decreases in the order: 2024 Al alloy>Al-Cu alloy>Al-Si alloy at a pouring temperature of 670 °C and a mold temperature of 25 °C. Feeding of liquid films at the end of solidification plays an important role in the propagation process of hot tearing. The decrease of hot tearing tendency is attributed to the feeding of liquid film and intergranular bridging. [ABSTRACT FROM AUTHOR]

Bimodal silica and aluminosilicate materials containing mesopores and macropores were synthesized by hydrothermal method using sodium silicate, aluminum nitrate, P123 triblock copolymer, n-decane, hydrochloric acid and water. The uncalcined silica compound was previously characterized by thermogravimetry, and the calcined materials were characterized by X-ray diffraction, infrared absorption spectroscopy, and scanning electron microscopy. The obtained materials have bimodal characteristics with mesopores and macropores in their structures, which pores are ideal for processing bulky molecules, such as hydrocarbons present in heavy oil. In this work, the synthesized silica and aluminosilicate were used as materials for distillation and cracking of a petroleum sample with oAPI = 17.4. The process was evaluated by thermogravimetry, in the temperature range from 25 to 900 °C, in a nitrogen atmosphere. The determination of activation energies (Ea) as a function of the degree of conversion was obtained by using the Ozawa–Flynn–Wall kinetic model and at heating rates of 5, 10 and 20 °C min−1. It was observed that the catalytic cracking of the oil presented Ea of 196 kJ mol−1 for 90% conversion. At the same conversion, for the oil containing 10% of Si-MBB catalyst, the Ea decreased to 170 kJ mol−1 and for AlSi-BMM, the Ea was 155 kJ mol−1, showing the efficiency of bimodal materials containing mesopores and macropores in its structure for processing of heavy oil. [ABSTRACT FROM AUTHOR]

The hot-tearing susceptibility (HTS) of Mg-6Zn-xGd (x=0.5, 1, 2, 3, 4, 6) alloys was evaluated using a constrained rod casting (CRC) method. The results show that the HTS curve follows a typical "Λ" shape with the increase of Gd content. The Mg-6Zn-2Gd alloy has the highest while Mg-6Zn-6Gd alloy has the lowest HTS value. The hot-tearing behavior characteristics of Mg-6Zn-xGd alloys were further studied through a multifunctional hot-tearing test device. According to the dendrite contact point inferred from the stress curve, the Clyne-Davies criterion was modified and found to be accurate in predicting the HTS of Mg-6Zn-xGd alloys. Microstructure observation reveals that the grain size and the volume of eutectic liquid are the two key factors affecting HTS of Mg-6Zn-xGd alloys. The large grain with columnar structure can easily promote initiation and propagation of hot-tearing due to the poor feeding and coordinating deformation capability, which have a harmful effect on HTS. A higher volume fraction of eutectic phase can refill the cracking and provide continuous feeding channels by dendrite bridge and thicker liquid film, thus increase the hot-tearing resistance. [ABSTRACT FROM AUTHOR]

Two semi-synthetic clay-based catalysts were prepared. These catalysts were obtained by incorporating lanthanum oxide (Cat1) and chromium oxide (Cat2). They were then tested for catalytic cracking of a heavy petroleum residue (fuel). The two formulations were carried out in the presence of silica to improve their acidity then underwent an acid activation. The catalysts obtained were characterized by various methods (XRD, FTIR, ICP-OES, SEM). The results showed that the incorporation of oxides and the addition of silica improves the structural characteristics of the final products. The support used was a kaolinite rich clay, having a specific surface area of 15.26 m2/g and acidity of 14 meq/g. These values increase, respectively, to 456.14 m2/g and 50 meq/g for Cat1 and to 475.12 m2/g and 57 meq/g for Cat2. The influence of the type of oxide incorporated, the specific surface area, the porosity and the acidity of the catalysts on their catalytic activity was studied. The nature of the oxide used proved to be decisive on the quality of the catalyst. Thus Cat1, prepared with lanthanum oxide, showed the best performance in cracking the petroleum residue achieving a conversion rate of 74.13% compared to 66.53% for cat2. [ABSTRACT FROM AUTHOR]

Steel ingot with a large height-to-diameter ratio is utilized to produce multiple products by one stock in practice. Water cooling is a usual way to enhance production efficiency. However, the combination of the two factors will generate internal defects, such as shrinkage porosity and hot crack. The characteristic of internal shrinkage crack in a 10 t water-cooled steel ingot with a large height-to-diameter ratio was examined by an ultrasonic test. A slice was sectioned from the ingot middle part where billets containing star-like crack were further extracted. The billets were examined by X-ray high energy industrial CT, and the compactness was reconstructed in three dimensions. Microstructure near the crack was observed using scanning electron microscopy, and the solidification process and grain size were studied by high temperature confocal microscopy. Moreover, thermomechanical simulation and post-processing were carried out to analyze the formation of shrinkage porosity and hot crack. A new criterion considering mushy zone mechanical behavior in brittle temperature as well as grain size distribution was proposed to evaluate hot cracking potential in the ingot. The results show that a deep shrinkage porosity band easily forms in the center line of such an ingot with a large height-to-diameter ratio, and water-cooling further generates excessive tensile stress tearing the liquid films around the porosities. Then, hot cracks begin to propagate along grain boundaries. The grain size in the upper and center of the ingot is large, which leads to an inverted cone shape defects zone in the ingot center. [ABSTRACT FROM AUTHOR]

High Nb-TiAl (Ti-44Al-8Nb-0.2W-0.2B-0.5Y, at.%) ingot was fabricated by vacuum arc remelting (VAR). The as-cast ingot was hot-isostatic pressed (HIP) and homogenizing annealing processed. The influence of heat treatment temperature and thermomechanical processing on the microstructure and tensile property of the alloy was investigated by X-ray diffractometry (XRD), scanning electron microscopy (SEM) and tensile tests. It was found that the high Nb-TiAl alloy after HIP and annealing was mainly composed of coarse α2/γ lamellae, β/B2 phase and γ phase and the solidification path of this alloy was: L→L+β→β→α+β→α→α+β+γ→α2+β+γ. The water quenching results showed that the alloy was in α single phase region at 1,340 °C. After heating at 1,340 °C for 30 min followed by furnace cooling, the alloy showed a full lamellar microstructure and its ultimate tensile strength was about 538 MPa, with an elongation of 0.3% at room temperature. Free-crack forged pancakes with fine-grained fully lamellar structure (FFLS) were obtained with an initial deformation temperature of 1,340 °C and the ultimate tensile strength of forged alloy was about 820 MPa, with an elongation of 0.9% at room temperature, which was much higher than that of alloy after HIP and annealing because of microstructural refinement. [ABSTRACT FROM AUTHOR]

During fire investigation, gasoline, as a common accelerant, is produced by petroleum cracking. However, the pyrolysis residues of other petrochemicals may interfere with gasoline identification. Polymerised styrene butadiene rubber (SBR) 1502 has combustion characteristics highly consistent with those of gasoline, thus having a great effect on gasoline identification. This study investigated the pyrolysis process of SBR 1502 by using thermogravimetric–differential scanning calorimetry (TG–DSC) and gas chromatography–mass spectrometry (GC–MS) to examine the residues during combustion stages, including pyrolysis and nonpyrolysis stages. The results indicated that 2,3-dimethylnaphthalene in the pyrolysis residues of SBR 1502 in pyrolysis stages 2 and 3 was lacked. However, when SBR 1502 only undergoes the first pyrolysis stage or even earlier (Nonpyrolysis stage), the characteristic components in the residue are similar to gasoline. In addition, mathematical methods were applied to analyse relevance and differences between SBR 1502 and gasoline. The conclusion was that the Pearson product-moment correlation was > 0.990, which may interfere with the identification, and principal component analysis could efficiently distinguish them. The current results can provide an accurate and feasible basis for fire investigation. [ABSTRACT FROM AUTHOR]

Understanding the mechanisms of petroleum thermal cracking is critical to develop more efficient and eco-friendly petroleum cracking processes. Asphaltenes are the main component of petroleum subjected to cracking processes. Thermal cracking mechanisms of petroleum were explored by computational methods using 1,2-diphenylethane (DPE) as a model molecule in this study. The overall mechanisms were divided into four steps including initiation, H-transfer reaction, H-ipso reaction, and termination represented by seven reactions. We carried out extensive quantum chemistry calculations at high levels of theory to accurately explore the minimum energy pathways as the mechanisms of the proposed reactions. The reaction energy and barriers in terms of enthalpy and free energy and their temperature dependence were calculated in the vacuum and in both polar and nonpolar solvents using the polarizable continuum model (PCM) method. The temperature dependence of the target reaction barriers are characterized in different environments and provides computational guidance for future development for petroleum thermal cracking. As the first reported systematic investigation of petroleum cracking mechanisms, this study provided a comprehensive theoretical description of petroleum cracking processes with valuable information about temperature and solvent dependence. [ABSTRACT FROM AUTHOR]

Flowsheets based on the results of experimental studies and detailed kinetic modeling were suggested for oxidative cracking of oil refinery gas components to obtain ethylene, CO, and hydrogen. The calculations show that oxidative cracking alone does not allow production of ethylene and СО in ratios required for the further catalytic carbonylation and hydroformylation of ethylene. Matrix conversion of a part of oxy-cracking products is suggested as an additional step for producing CO and hydrogen. [ABSTRACT FROM AUTHOR]

Abstract: This paper completes our work on calculation of a chemical-technological complex for coprocessing cracking and pyrolysis gases on the basis of a method developed for optimal design of a chemical-technological complex (CTC) with progressive fulfilment of steps aimed at optimizing the entire complex with consideration of the mutual influence of all its processes. Using the mathematical model of the entire CTC with complete kinetic models of all the selected processes as a basis, its optimization was performed and the optimal regimes with a maximum production capacity for all the target products were selected for these processes. Advisable routes of the motion of byproducts were selected. The resulting closed flowsheet of the chemical-technological complex with notations of all inlet and outlet flows and established couplings of material and recycled flows between all the reactor elements was presented. Using the complete mathematical model and the selected economic criterion and optimization method as a basis, the chemical-technological complex was subjected to global optimization and, as a consequence, the optimally consistent material flows of the entire complex were determined with the resulting maximization of its rate-of-return, i.e., an appreciable increase in the economic efficiency of CTC operation. [ABSTRACT FROM AUTHOR]

The cracks in a rock tend to initiate, propagate, and coalesce under loading. Based on the digital image correlation (DIC) method, uniaxial compression tests are carried out on rock-like specimens with various arrangements of two parallel cracks. The full-field strain and failure features of the rock-like materials are observed and analysis by a self-developed code. Two process zones are defined according to the differences between the shear strain field and the tensile strain field: a shear process zone and a tensile process zone. The following results are obtained in this study. (1) Three coalescence modes can be observed using the DIC method: a shear coalescence mode, a tensile coalescence mode, and a mixed coalescence mode. (2) At the microscopic level, the bridge angle and crack arrangement affect the formation of the process zone; at the macroscopic level, they determine the crack propagation path and the failure mode. (3) The peak strength of the rock-like specimen is related to the crack inclination angle and the bridge angle. (4) Numerical modeling by the expanded distinct element method and the strain strength criterion simulates the different coalescence modes of the experimental study efficiently. [ABSTRACT FROM AUTHOR]

Increasing the deeper understanding of the thermal damages and failure mechanisms of sandstone undergoing thermal treatments at different temperatures is a key concern for deep-mining and underground coal gasification processes. In this research study, a scanning electron microscope (SEM) apparatus, JSM-5410LV, which was equipped with a built-in digital electro-hydraulic servo loading system, was applied to carry out a series of three-point bending tests on Pingdingshan sandstone following heat treatments at elevated and high temperatures ranging from 25 to 600 °C. The subcritical crack initiation load, peak load, and elastic modulus were found to increase with the increases in the thermal treatment temperatures until a maximum was achieved at 125 °C, after which decreases were observed. However, it should be noted that there were sudden drops observed for the specimens after the thermal treatment temperature reached 150 °C due to the thermal diffusivity of the cement. The subcritical crack growth length was theoretically calculated, and a digital speckle correlation method (DSCM) was applied to verify the initial load and subcritical crack growth length. It was found that the fracture toughness fluctuated significantly when the thermal treatment temperature ranged from 25 to 125 °C, and reached a peak of 47.45 MPa mm0.5. It was also observed that, as the temperature was raised from 175 to 600 °C, the fracture toughness gradually decreased. The subcritical crack growth mode was determined to be intra-granular cracking following the thermal treatments below 125 °C, while a mixture of intra-granular and trans-granular cracking occurred in the specimens which experienced thermal treatments of 175 °C. The relationship between heat treatment temperature and subcritical crack growth was derived, which could be used to develop geothermal energy extraction from the critical temperature resources. [ABSTRACT FROM AUTHOR]

A study was carried out on the effect of ionic liquids (morpholine formate and aniline formate) on the desulfurization of catalytic cracking gasoline and coking gasoline. A relationship was found between the extent of desulfurization of the gasolines on the ionic liquid:gasoline ratio and the duration of the extraction. An increase in the ionic liquid: coking gasoline ratio from 1:10, to 1:5, and then 1:1 led to enhancement of desulfurization t o 19.5%, 21.5%, and 49%, respectively. An increase in the ionic liquid: catalytic cracking gasoline ratio from 1:3 to 1:1 led to an increase in the desulfurization of this gasoline from 40.2% to 65.4% for 0.2 h extraction time. When the extraction time was extended to 0.5 h, the desulfurization of catalytic cracking gasoline was enhanced from 50 to 70%. [ABSTRACT FROM AUTHOR]

Data are given on the cracking of vacuum gas oil with HY zeolite catalysts on aluminum pillared natural calcium montmorillonite under vigorous cracking conditions in laboratory reactors of different volumes with a fixed catalyst bed at 500-600°C. Increasing the cracking temperature and contact time of the vacuum gas oil with the catalyst was shown to increase the yield of the gas phase. The greatest gas yield was 42%. In this case, the gas contained C2 - C4 alkenes, including 28% propylene. We concluded that it should be possible to use aluminum pillared calcium montmorillonite as a component of a zeolite cracking catalyst for petrochemical processes. [ABSTRACT FROM AUTHOR]

Currently, the manual method using hand-held infrared temperature measurement instruments for measuring temperatures on the external surfaces of ethylene cracking furnace tubes is highly subjective and is affected by a number of prominent issues, such as the high temperature working environments, which leads to low efficiency and poor measurement accuracy. Hence, an automatic temperature measurement system based on infrared light is designed and realized. In the system, a dual-phase drive synchronization method is proposed to rotate the thermodetector during horizontal movements, thus realizing automatic batch temperature measurements of the furnace tubes. Moreover, a temperature processing algorithm is developed to automatically identify furnace wall and tube surface temperatures, filter out abnormal temperatures and select only high-quality temperature measurements prior to calculating the final result. Real temperature measurement experiments demonstrated that the dual-phase drive temperature measurement system and temperature processing method are effective and efficient. Compared with the traditional manual way, temperatures obtained using the proposed system are more stable and accurate. [ABSTRACT FROM AUTHOR]

Proppant embedment in hydraulic fracturing can reduce remarkably the fracture width and thus damage the fracture conductivity. This paper describes a study of the proppant embedment mechanism. Two groups of experiments were carried out. A proppant embedment mechanism was proposed. An analysis showed that proppant embedment is not an elastic process but could be a plastic or even failure process depending on the surface microstructure of the formation core. [ABSTRACT FROM AUTHOR]

Oxidation studies were performed on solution-annealed Alloy 600 in high-temperature steam at 400 °C and in simulated pressurized water reactor primary water at 320 °C under environmental conditions where this alloy is known to be susceptible to intergranular stress corrosion cracking. Advanced analytical transmission electron microscopy characterization and detailed scanning electron microscopy analysis highlighted extensive preferential intergranular oxidation as well as enhanced Cr and O diffusivities associated with this oxidation. These findings, as well as the preferential intergranular oxidation susceptibility and diffusion-induced grain boundary migration, are discussed in terms of their roles as precursors to stress corrosion cracking. [ABSTRACT FROM AUTHOR]

Typically, cracking can be observed on the rubber surface when it is stretched and exposed to the ozone. Ozone-induced stress cracking is considered a problem as it contributes to diminishing the appearance and serviceability of rubber products. Ozone concentration form cracks which cause potential failure in the rubber. This study investigates the influence of ozone exposure and discusses most of the effects resulting from the ozone attack. Water serves a barrier and protects rubber from the ozone attack. Many cracks formed on the rubber surface at a high strain compared to that of a low strain. The distribution of crack lengths represents a complex function of time and strain. The chemical reaction of ozone proceeds in the absence of strain which results in a shiny appearance and is tacky due to uniform occurrence of ozonolysis on the rubber surface. [ABSTRACT FROM AUTHOR]

A common failure in a certain type of gas turbine, observed during the first periodic inspection, is radial cracks in the tip plate of gas fuel nozzles. Here, each gas turbine has 18 nozzles. In all nozzles and in all similar units, these cracks of lengths ranging from 1 mm to a maximum of 14.5 mm are observed. As prescribed by the manufacturer, the defective part must be removed and replaced by welding and machining of a new one. But this problem is repeated and observed in the next periodic visits, and in all units. Depending on the number of nozzles in each gas turbine unit and the number of units in total, these repairs are very expensive and time-consuming. In this paper, the failure is analyzed and the causes of the cracks in the nozzles are investigated. Studies show that the main causes of nozzle failure are residual stresses caused by welding and thermal stresses caused by the start-up and shutdown processes. According to results, a solution has been proposed to release these residual and thermal stresses. After the implementation of this method in 1998, no more failure has been reported by the repair team, which proves the effectiveness of this solution. Since this paper has been prepared based on technical reports from the years between 1996 and 1998, the cited references of this paper are these technical reports. [ABSTRACT FROM AUTHOR]

A novel strategy that combines steam reforming of bio-oil and recovering waste heat from blast furnace (BF) slag was proposed, and the thermodynamic characterizations of steam reforming of bio-oil model compounds recovering waste heat from BF slag for hydrogen production were investigated. When temperature ranged from 600 to 700 °C, hydrogen yield and its component reached maximum, about 100 mol kg−1 bio-oil model compounds and 70%, respectively. The higher mole ratio of steam to carbon in bio-oil (S/C), the higher hydrogen yield and its component were obtained, but according to the practical process, the most suitable S/C was 4. The ordinary pressure (1 bar) was considered as the optimum pressure for steam reforming of bio-oil model compounds recovering waste heat from BF slag. At lower temperatures (below 500 °C), BF slag could promote hydrogen yield, but it slightly decreased equilibrium yield of hydrogen at the optimal conditions. Besides, BF slag could promote hydrogen component at lower temperatures (below 600 °C), but it had little effect at the optimal conditions. Solid carbon should be reduced during steam reforming of bio-oil compounds recovering waste heat from BF slag. [ABSTRACT FROM AUTHOR]

We determine the chemical changes associated with viscosity reduction when heavy oil is cracked in subcritical water. The viscosity reduction has a temperature threshold for onset of 290 °C-this suggests an enhanced acid cracking regime associated with the maximisation of water dissociation at these conditions aided by the already increased solubility. The mean molecular weight is reduced by nearly 50%. Oxygen and sulphur are reduced by about half of this-either by expelled gas effluent (H2S) or by conversion into mono-aromatic base sulphur-containing structures. The amount of lower branched paraffins is increased. [ABSTRACT FROM AUTHOR]

The effect of temperature on the cracking of pond acid tar and acid tar neutralized with lime has been studied. The formation of H2S or SO2 is determined by the amount of sulfuric acid in the tar. Liquid hydrocarbons obtained from neutralized acid tar are characterized by low sulfur content. [ABSTRACT FROM AUTHOR]

A kinetic model of the isothermal initiated cracking of tar has been developed, and parameters of the reactions have been found. A computer model of isothermal thermo-oxidative cracking of tar is implemented to determine kinetic constants, and a criterion for mismatching the calculated and experimental data is minimized. The kinetic simulation of the process has been carried out in isothermal regime so that the parameters that allow for increase in yield of target products have been determined. [ABSTRACT FROM AUTHOR]

This work aims to investigate the importance of biomass char and the metal oxides in the ash in tar cracking during the volatile-char interactions. Experiments were carried out in a two-stage fixed reactor, and corncob, one typical agricultural biomass rich in potassium, was chosen as raw material. Results showed that char and char-supported potassium catalysts have good activity for tar elimination due to the good absorbability of char and catalytic property of potassium. In particular, tar conversion efficiency can reach 95.8% by using 1.5 K-char catalyst at 700 °C. The reforming reactions can be significantly enhanced during the volatile-char interactions in the presence of char and char-supported potassium catalysts. As a result, the syngas yield increased significantly with increasing temperature and supported K, particularly the combustible gases including H, CO and CH. Physical and chemical structure of char changed due to reforming reactions related to the carbon, while the content of potassium was almost unchanged. [ABSTRACT FROM AUTHOR]

Joint thermal treatment of heavy oil and liquid products of fast wood pyrolysis is investigated. Thermal analysis shows that the coke yield does not increase if the liquid products are added up to 20 mass%. The liquid wood-pyrolysis products decompose much earlier than heavy oil. However, the decomposition of the blends is essentially the same as pure-oil decomposition. [ABSTRACT FROM AUTHOR]

A model describing crack length distribution is proposed on the basis of experimental laws governing the formation and growth of fatigue cracks in a flat specimen with multiple stress raisers. The density of this distribution corresponds to that of Pareto and can be used to describe the accumulation of scattered defects in a wide range of cracking scale. The critical values of Pareto distribution exponent, which correspond to the limit states of the multiple fracture of solid bodies, have been substantiated. [ABSTRACT FROM AUTHOR]

The yields of gasoline, light and vacuum gas oils, and gas fraction in thermal cracking of heavy oil residues (visbreaking) were mathematically modeled. Calculation formulas with high statistical characteristics were obtained. [ABSTRACT FROM AUTHOR]

Eleven crude oils from the Gulf of Suez and Western Desert of Egypt have been used for the geochemical study. They have been analyzed for their metals, nitrogen and sulfur contents. Application of geochemical markers based upon these constituents has shown that crude oils could be correlated or differentiated according to their geologic age. The V/Ni, Ni/S, V/N, Ni/N, and S/N markers were almost uniform in Miocene oils, revealing the same origin, yet showing marked differences in Cretaceous crude oils reflecting varying degrees of their maturity, source materials, depositional environment and migrational history. The significance of analyzing the non-hydrocarbon constituents of the heavy petroleum fractions were extended to protecting the catalyst used in cracking processes. The results showed that trace metals and nitrogen contents are within the permissible limits in gas and diesel oils yet they are much beyond those limits in the heavier fractions. [ABSTRACT FROM AUTHOR]

The influence of modifiers affecting the structural organization of a petroleum system and the kinetics of oxidation of vacuum distillation bottoms have been studied. It has been shown that the introduction of modifiers into the petroleum feedstock alters the ratio of the dispersed phase to the dispersion medium, thereby affecting the rate of the oxidation process. It has been found that the main factor determining the performance of modifiers affecting the structure of the petroleum system is the modifier nature. The maximum concentration of modifiers in the vacuum tower bottoms (VTB) was 5.0 wt %. The dependence of the oxidation rate upon the duration of oxidation has been determined for the modifiers. It has been shown that brown-coal pyrolysis tar introduced into VTB has an inhibitory effect, and oil shale pyrolysis tar and a diamond blend initiate the oxidation process. For blown asphalts produced from modified and unmodified VTB, expressions relating the softening point and penetration have been obtained. The properties of different blown asphalts obtained from the feedstock modified with the test additives at optimal concentrations have been compared. [ABSTRACT FROM AUTHOR]

Commercial metals and alloys like carbon steels, stainless steels, and nickel-based super alloys frequently encounter the problem of environmentally assisted cracking (EAC) and resulting failure in engineering components. This article aims to provide a perspective on three critical industrial applications having EAC issues: (1) corrosion and cracking of carbon steels in automotive applications, (2) EAC of iron- and nickel-based alloys in salt production and processing, and (3) EAC of iron- and nickel-based alloys in supercritical water. The review focuses on current industrial-level understanding with respect to corrosion fatigue, hydrogen-assisted cracking, or stress corrosion cracking, as well as the dominant factors affecting crack initiation and propagation. Furthermore, some ongoing industrial studies and directions of future research are also discussed. [ABSTRACT FROM AUTHOR]

To create a chemical-technological complex for the joint processing of cracked gases and pyrolysis gases, the technique of its design was developed. Based on the design capacity of the pyrolysis and cracking units, mass flows of cracked gases and pyrogas entering the chemical-technological complex have been calculated. A scheme has been developed for the proposed complex. To reduce the dimension of the design task, the whole complex was divided into a separate region. Based on the stoichiometric and kinetic models, the calculation of material balances for all processes included in the largest ethylene region has been carried out. The technological parameters were taken from the operated industrial units and processes on the stage of design. The industrial productivity of reactor elements by the targeted products has been determined. [ABSTRACT FROM AUTHOR]

The process of the atmospheric-oxygen-induced cracking of heavy oils of various nature and compositions in a continuous flow reactor has been studied. The process variables for conversion of heavy oils into gasoline and diesel fractions have been determined that ensure the maximum yield of the above fractions with simultaneous production of marketable heavy residues. The developed technology can be applied in industry upon minor upgrading of the operating thermal cracking or visbreaking units. This upgrade will result in a considerable increase in the oil refining depth. [ABSTRACT FROM AUTHOR]

During surveys, water layers may interfere with the detection of oil layers. In order to distinguish between oil and water layers in a porous cracked medium, research on the properties of cracks and oil and water layers and their relation to acoustic logging rules is essential. On the basis of Hudson's crack theory, we simulated oil and water layers in crack-porous medium with different crack parameters corresponding to the well-field response. We found that in a cracked medium with high crack angle or low number density of cracks, compressional and shear wave velocities are sensitive to crack characteristics; further, these velocities are more sensitive to crack characteristics when the waves propagate through the water layer than when they propagate through the oil layer. Compressional and shear wave velocities increase with an increase in crack angle: in the water layer, the increase is approximately linear. On comparing the full waveforms observed in the oil and water layers, we find that the amplitudes of most waves are higher in the water layer. Among the considered waves, the Stoneley wave suffers maximum amplitude attenuation in the oil layer. The maximum excitation intensity for oil layer is greater than that for the water layer. These results can guide further cracked media logging field exploration work. [ABSTRACT FROM AUTHOR]

Со-Мо/AlO and Ni-W/AlO catalysts were tested in hydrotreating of light cycle oil from catalytic cracking, of the straight-run gasoil, and of their mixture under typical hydrotreating conditions used in industry. The catalysts prepared using PMo and PW heteropoly acids exhibit high catalytic activity. The Со-Мо/AlO catalyst is more active in hydrodesulfurization and hydrogenation of olefin and diene hydrocarbons, whereas the Ni-W/AlO catalysts are more active in hydrogenation of mono- and polycyclic aromatic hydrocarbons. Comparison of the quality characteristics of the hydrogenizates obtained with the requirements of the technical regulations shows that the required levels of the sulfur content and cetane number of the hydrogenizates at practically accessible process parameters can be reached for mixtures of the straight-run gasoil and light cycle oil from catalytic cracking with high content of the latter component only when the process with the Со-Мо/AlO system and Ni-W/AlO catalysts is performed in two steps. [ABSTRACT FROM AUTHOR]

The production of high premium fuel is an issue of priority to every refinery. The trans-hydrogenation process is devised to convert two low valued refinery cracked products to premium products; the conversion processes involve the combination of dehydrogenation and hydrogenation reaction as a single step process. The paper reviews the recent literature on the use of catalysts to convert low value refinery products (i.e. alkanes and alkynes or alkadienes) to alkenes (olefins) by trans-hydrogenation. Catalysts based on VO, CrO and Pt all supported on alumina have been used for the process. However, further studies are still required to ascertain the actual reaction mechanism, mitigating carbon deposition and catalyst deactivation, and the role of different catalysts to optimize the reaction desired products. [ABSTRACT FROM AUTHOR]

The effect of temperature (530-590°C), weight hourly space velocity (2.5-7.0 h), and the Si/Al ratio of the ZSM-5 zeolite (30, 55, 80, 300) on the cracking of a butane-butylene fraction containing 85 wt % butylenes has been studied. The HZSM-5 zeolite has been modified with phosphorus. The effect of modification on the catalyst activity in cracking reactions has been studied. The ethylene and propylene yield achieves 38.4 wt % at a degree of conversion of butylenes of 81.5%. The ethylene to propylene ratio is 0.55. [ABSTRACT FROM AUTHOR]

Different variants of preconditioning of wet and associated petroleum gases and controlling the characteristics of the resulting fuel gases have been considered. Introduction of an additional step of preliminary oxidative conversion (prereforming) of natural and associated petroleum gases makes it possible to oxidize selectively the 'heavy' low-octane components of a complex hydrocarbon mixture and obtain fuel gas for power plants with a high methane number and a required lower heating value. Fuel characteristics of the gases obtained via partial oxidation can be further improved by admixture of gas-piston engine exhaust gas in an amount of about 100 m/1000 m to the air-fuel mixture. The version of controlling the fuel characteristics of complex gas mixtures, as described in the paper, is characterized by simplicity of engineering design, high feedstock flexibility, and the possibility to create simple-to-use modular automated systems for conditioning hydrocarbon gases in small gas fields or fields distant far from power plants. [ABSTRACT FROM AUTHOR]

Cracking residual fuel oil separated from a mixture of Azerbaijanian crude oils using catalysts based on aluminum plant sludges containing up to 50-70% FeO was investigated. It is shown that the yield of liquid products, including motor fuels, upon residual fuel oil cracking at 550 °C rises to 80 and 70 wt. %, respectively. Steam gasification of carbonized and partially reduced catalyst allows production of gas with hydrogen content of up to 72.84 vol. %. [ABSTRACT FROM AUTHOR]

The riser reactor is the key unit in the fluid catalytic cracking (FCC) process. As the FCC feedstocks become heavier, the product mixture of oil, gas and catalysts must be separated immediately at the outlet of the riser to avoid excessive coking. The quick separation system is the core equipment in the FCC unit. China University of Petroleum (Beijing) has developed many kinds of separation system including the fender-stripping cyclone and circulating-stripping cyclone systems, which can increase the separation efficiency and reduce the pressure drop remarkably. For the inner riser system, a vortex quick separation system has been developed. It contains a vortex quick separator and an isolated shell. In order to reduce the separation time, a new type of separator called the short residence time separator system was developed. It can further reduce the separation time to less than 1 s. In this paper, the corresponding design principles, structure and industrial application of these different kinds of separation systems are reviewed. A system that can simultaneously realize quick oil gas separation, quick oil gas extraction and quick pre-stripping of catalysts at the end of the riser is the trend in the future. [ABSTRACT FROM AUTHOR]

A study of cracking failure of three-way T junctions between inlet manifold and branch pipes in large-scale hydrogen reformer furnaces in terms of pipe material, operation medium, properties of cracking zone material, and vertical displacements of inlet manifold and branch pipes is presented. The results revealed that cracking failures of three-way T junctions can be attributed to the stress concentration, which was caused by incongruous vertical deformations of inlet manifold and branch pipes, as well as variations in horizontal deformation heights of branch pipes. The incongruous displacements of inlet manifold and branch pipes were significantly mitigated by optimization design of the suspension device of the inlet pipe using the finite element method. The vertical displacement differences between inlet manifold and branch pipes and the east-west vertical displacement differences between the five branch pipes were reduced by 48 and 91.5%, respectively. Bending of three-way T junctions was relieved and torsions were eliminated, resulting in mitigation of stress concentration. As a result, the maximum equivalence stress was reduced by 40%, satisfying strength requirements. In this way, cracking failures of inlet manifold in hydrogen reformer furnace were prevented and stable hydrogen production was guaranteed. [ABSTRACT FROM AUTHOR]

Hydraulic slotting, an efficient technique for underground enhanced coal bed methane (ECBM) recovery, has been widely used in China. However, its pressure relief mechanism is unclear. Thus far, only limited research has been conducted on the relationships among the mechanical properties, flaw parameters, and crack propagation patterns of coal after hydraulic slotting. In addition, because of the limitations of test methods, an in-depth information is not available for this purpose. In this work, numerical models of specimens containing combined flaws are established based on particle flow code method. Our results provide insights into the effects of flaw inclination angle on the mechanical properties, crack propagation patterns, and temporal and spatial evolution rules of stress field in specimens containing combined flaws during the loading process. Besides, based on the initiation position and underlying mechanism, three types of crack initiation modes are identified from the failure processes of specimens. Finally, the crack propagation pattern is quantitatively described by the fractal dimension, which is found to be inversely proportional to the uniaxial compressive strength and elastic modulus of the specimen. To verify the rationality of the numerical simulation results, laboratory tests were conducted and their results match well with those obtained from the numerical simulation. [ABSTRACT FROM AUTHOR]

A variety of materials are used in the Oil & Gas industry ranging from carbon steel, stainless steel to nickel alloys, etc. including non-metallic materials as well. Amongst these, carbon steel is the industry favorite because of many of its desirable attributes like machinability, weldability, availability, and cost. Wide use of carbon steel in the industry is also due to the presence of required properties for the specific application. In spite of carbon steel's wide uses, poor workmanship, improper heat treatment, or negligent manufacturing processes can reduce its service life and also can lead to unexpected failures. One such failure case involves carbon steel plate meant for construction of a tank that failed by cracking immediately after the welding operation. A detailed investigation was carried out by means of visual examination, metallographic and chemical analysis, SEM, and EDAX analysis. Microstructure revealed banded pearlitic structure along with a number of inclusions, a few of which were elongated. In conclusion, stresses due to weld joint restraint, elongated inclusions, and high transverse direction stresses after welding resulted in lamellar tearing which propagated in the linear direction along the weld line. [ABSTRACT FROM AUTHOR]

The physical interpretation of the J integral (i.e., J integral) is clear. J integral is the energy release rate associated with crack extension (i.e., translation of the crack in the x direction). However, the physical interpretation of the J integral remains unclear. In this study, different crack translations in the x direction were selected and tested by calculating the energy release rates associated with the crack translations and comparing them with the theoretical value of the J integral. [ABSTRACT FROM AUTHOR]

HY zeolite catalysts on montmorillonite, pillared with aluminum hydroxo complexes in different concentrations, have been tested in the cracking of heavy vacuum gas oil (VGO) from the Shymkent refinery (Kazakhstan). It has been shown that the VGO cracking activity of the catalysts is directly related to the textural and acid properties of the samples. The hydrocarbon group and fractional compositions of cracked gas-oline have been determined. [ABSTRACT FROM AUTHOR]

The results of modeling of thermal cracking of oil sludge activated by electromagnetic radiation are reported. An experimental-statistical model of dependence of wide gas oil fraction yield on radiation frequency, electromagnetic radiation power, and oil sludge activation time is obtained to optimize the cracking process conditions. [ABSTRACT FROM AUTHOR]

The problem of prompt speed and density profile mapping based on mathematical modeling of particle motion in the acceleration section of catalyst pneumotransport lines is discussed. An algorithm is developed to calculate the distribution of these parameters along the longitudinal coordinate of reactor-lifts to improve ergonomic efficiency of operation of reaction-regeneration systems used in oil refining and petrochemical industries. [ABSTRACT FROM AUTHOR]