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To prevent the occurrence of thermal runaway accidents in semibatch reactors (SBRs), it is desirable and practicable to develop criteria that can distinguish between the safe and runaway operating regions. In this article a new safety criterion, namely, the adiabatic criterion, has been developed for SBRs in which liquid homogeneous as well as liquid-liquid heterogeneous reactions with arbitrary reaction orders occur. It states that an SBR is operated in the potential runaway situation if the value of the adiabatic criterion exceeds zero at a segment of the reaction path. Numerical results show that the adiabatic criterion is more conservative than the two other criteria (divergence criterion and target temperature criterion). However, the adiabatic criterion is not suitable to reactions with autocatalytic behaviors. Also knowledge of activation energies and reaction enthalpies is necessary to utilize the adiabatic criterion. [ABSTRACT FROM AUTHOR]

Heat transfer and reaction behavior of aviation kerosene were investigated numerically and experimentally at a supercritical pressure. A global thermal cracking and catalytic reforming reaction model were modified and developed based on the experimental data. A set of surrogate components for aviation kerosene was built and its thermodynamic properties were predicted. Interactions among heat transfer, cracking and catalytic steam reforming reactions were simulated in a micro-channel reactor. Comparison between calculation and experiment showed that the numerical model can predict the wall and outlet fuel temperatures with an error not exceeding 5%. The conversion rate of kerosene and water were also in good agreement with experimental data. Heat transfer deterioration phenomenon can be observed when fuel contains water. Fuel with catalytic steam reforming reactions had the advantage of weakening the heat transfer deterioration and obvious promotion in heat sink. Heat transfer process can be divided into four sub-regions: entrance, gasification, transition and interactive reaction regions. The two kinds of reactions occurring in the reaction region significantly improve the heat sink of hydrocarbon fuel. Interactions between cracking and reforming reactions illustrated that the reaction region were considerably moved ahead due to the existing of steam reforming reactions, resulting in lower fuel temperature which led to a lower rate of thermal cracking and conversion. Thermal cracking reaction was inhibited by catalytic steam reforming reactions. [ABSTRACT FROM AUTHOR]

The thermal evolution of phytol in thecatalytic environmentsof reduction, montmorillonite catalysis and illite catalysis has been investigated. The results show the following: (1)Montmorillonite and illite facilitate the defunctionalization and further cracking of phytol. (2) Pristane and phytane can no longer serve as effect biomarkers at the high thermal evolution stage due to loss of thermostability. (3) Ratios of pristane/phytane greater than 1derive from reduction and montmorillonite catalysis environments. However, the ratio of pristane/phytane was less than 1 under the condition of illite catalysis, which has not been shown before. [ABSTRACT FROM PUBLISHER]

The article presents the results of processing heavy oil residues initiated by atmospheric oxygen. We found that the introduction of a small amount of atmospheric oxygen (2–6%) in the thermo cracking reactor (thermo-oxidative cracking) significantly increases the yields of light fractions. E.g. A thermo cracking of vacuum residue (visbreacking) with the air supply to the soaker camera gives twice more light fractions than traditional visbreacking process (36% of petrol and diesel fractions compared to 10–15% in conventional process). Thermo-oxidative cracking of atmospheric residue gives up to 60% of light fractions. In order to obtain a mathematical description of the process needed for its subsequent industrial implementation we conducted experiments on thermo-oxidative cracking of atmospheric and vacuum residues in a continuous flow reactor with a wide variation of the process parameters. Based on the analysis of the experimental data a common scheme for thermo-oxidative cracking, a mathematical model of the process and its parameters were established. The model adequately describes all the experimental data obtained in the temperature range 430–460 °C, pressure 2–8 atm, retention times 4–33 min and relations oxygen/raw material 0,9–2,5 % wt. Industrial implementation of thermo-oxidative cracking needed just minimal modification of the existing thermal installations through the organization of air supply in the soaker chamber. This modification will increase the output of light fractions in the thermal processing heavy oil residues in 2–3 times with minimal capital investments. [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]

‘Chemical Looping Combustion’ (CLC) is an emerging clean combustion technology which offers an efficient route for fossil fuel combustion with inherent CO 2 capture. Beyond combustion, chemical looping is also applicable to selective oxidation of fuels to synthesis gas or olefins. In all these applications, the main advantage of chemical looping lies in the inherent air separation, which allows conversion of the fuel without nitrogen dilution. In the present work, we extend this inherent separation principle to separation of the product stream by demonstrating the formation of fully separated syngas streams from methane, i.e. the production of separate, high-purity CO and H 2 streams via (non-oxidative) methane cracking. CH 4 is first cracked catalytically over Ni, producing gaseous H 2 and solid carbon. The carrier is then periodically regenerated by burning off the carbon using CO 2 as oxidant, thus enabling the reduction of CO 2 to CO. Importantly, the Ni carrier is never oxidized during this cycle and hence acts as a “carbon carrier” rather than as an oxygen carrier as typical in chemical looping processes to-date. Autothermal process configurations are discussed, which allow reconciling the use of abundant natural gas reserves with the demand for clean, carbon-free energy production. [ABSTRACT FROM AUTHOR]

With the aim of investigating the solutions of ethane shortage in a commercial ethylene plant, addition of propane as supplementary feedstock and increasing steam to hydrocarbon ratio were proposed as possible strategies. These strategies were proposed to compensate for the ethane shortage in the thermal cracking unit of the commercial plant. Run length, ethylene yield, and propylene yield were considered as the determining factors to appraise the strategies. The major contribution of present work would be the investigation of effect of feed shift on the run length of the steam cracker. Regarding this, five different cases were investigated in real plant condition. To include all the aspects of process, a mathematical model with reasonable assumptions was developed and then validated against the real plant data. Based on the obtained results, increasing propane concentration leads to increase in propylene yield and decrease in ethylene yield. Besides, run length of process was obtained to be longer in the cases with higher propane content in the feed stream. [ABSTRACT FROM AUTHOR]

Alloy composition and morphology of the inner wall of steam cracking reactors are well-known key factors that affect their coking tendency. The effect of surface roughness on the coking tendency remains uncharted to date and has been studied here for a 35/25 Ni/Cr wt % alloy in a quartz jet stirred reactor equipped with an electro-balance under coil outlet industrially relevant ethane steam cracking conditions: Tgas phase = 1173 K, Ptot = 0.1 MPa, and XC2H6 = 70%. Up to 6 times higher initial coking rates have been observed during cyclic aging in an Rα surface roughness range of 0.15-7 μm, and cyclic aging proved to have an effect mainly on the catalytic coking behavior. No effect was observed on the asymptotic coking rates. Scanning electron microscopy, energy diffractive X-ray surface analysis, and cross section elemental mappings suggest that the effect of surface roughness and aging on the catalytic coking rate derives mainly from changes in the metal surface composition. The amounts of metallic Ni and Fe show an increasing tendency with increasing surface roughness, explaining the pronounced coke deposition. Using Ekvicalc, thermodynamic calculations were performed proposing that the amount of Cr2O3 gradually decreases followed by an increase of manganese chromite, MnCr2O4. [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 Chemical structures of oil sand bitumen (OSB) derived from Buton and Xinjiang oil sands were determined by elemental analysis, FTIR and 1 H NMR. The thermal cracking behaviors and evolving characteristics of gaseous products of Buton and Xinjiang OSBs were investigated by using thermogravimetric analyzer coupled with Fourier transform infrared spectroscopy (TG-FTIR). Additionally, the composition and distribution of volatile products formed from the fast thermal cracking process of these two OSBs were evaluated via pyrolysis gas chromatography-time of flight mass spectrometry (Py-GC/TOF-MS). Results indicated that Xinjiang OSB featured stronger polarity and contained more aliphatic structures with shorter chain length and larger branching degree compared to Buton OSB. Whereas Buton OSB possessed a larger amount of aromatic structures and its condensation degree was lower than that of Xinjiang OSB. The thermal cracking process of these two OSBs were both mainly consisted of two reaction stages, including volatilization stage and main reaction stage. The coke yields for Buton and Xinjiang OSBs were 15.51% and 16.76%, respectively. CO 2 , CO, CH 4 , C 2 H 4 , light C 2+ aliphatic hydrocarbons and light aromatics were the typical gaseous products released from the main reaction stages of both two OSBs. The evolving behavior of each of the typical gaseous products except for CO 2 and light aromatics during the thermal cracking process of Buton and Xinjiang OSB featured good similarity. The volatile products formed during the fast thermal cracking process of Buton and Xinjiang OSBs were mainly divided into five types of compounds, including alkenes (1-alkenes, iso-alkenes and cycloalkenes), alkanes (n-alkanes, iso-alkanes and cycloalkanes), diolefins, aromatics and sulfur compounds. Among of them, alkenes was the most predominant type in volatile products and 1-alkenes were the most abundant products for both two OSB. Furthermore, Buton OSB has higher selectivities of 1-alkenes and n-alkanes compared to Xinjiang OSB. [ABSTRACT FROM AUTHOR]

A series of nickel catalysts i.e. nickel sulfide (NiS), nickel phosphide (NiP) and nickel carbide (NiC) was investigated for hydrotreating of spent coffee oil to produce bio-hydrotreated fuel (BHF). Catalytic tests were carried out at 375–425 °C and 20–40 bar of initial H 2 pressure (before heating) with reaction time of 0–3 h. The activity of the catalysts are in the order of NiC > NiP > NiS; however NiC tended to promote cracking reaction resulting in high gasoline and gaseous yields. On the other hand, although NiS gives the lowest oil conversion, it is favorable to diesel yield with lowest methanation and cracking activity. Compared with decarboxylation (DCO 2 ) and hydrodeoxygenation (HDO), decarbonylation (DCO) was the major route for deoxygenation of coffee oil for all the catalysts. The ratio of (DCO + DCO 2 ) to HDO (as represented by C n-1 /C n ) decreased in the order NiS > NiC > NiP. Ketones as intermediate products (ca. 3 wt%) were detected in case of NiP. They could be generated via rearrangement of alcohol and keto-enol tautomerism. Significant amount of aromatics (4 wt%) with some isomerization products (0.9 wt%) can also be observed in NiS catalyzed liquid products while trace amount of these compounds were detected for NiP and NiC catalysts. Physiochemical analysis of the diesel fraction exhibited satisfactory properties. The density and kinematic viscosity were consistent with the specification of commercial bio-hydrogenated diesel, NExBTL. Since main products are straight chain hydrocarbons, high cetane index (>110) could be achieved. [ABSTRACT FROM AUTHOR]

This study examined the effects of microwave (MW) and ultrasonic (US) waves on an heavy crude oil sample from a reservoir in southwest Iran. The waves irradiated the sample from two to 10 min at two-minute steps. MW caused the temperature of the crude-oil sample to rise by selective heating of polar components and creation of hot zones; under US, heating was accompanied by a cavitation effect. MW at 2 and 4 min reduced the sample’s viscosity by inducing hot zones. At 2 min, the viscosity declined 16% due to cracking of heavy components such as asphaltenes, which have a higher capacity to absorb MW. As the radiation time increased after 4 min, the viscosity increased because light components escaped from the sample. However, US reduced the viscosity of the heavy crude oil sample at all time durations. The greatest reduction of viscosity was around 19%, at 4 min. The viscosity increased with irradiation time and then remained constant. Ultrasonic waves altered the viscosity by creating bubbles, which disintegrated the resin intermolecular bonds and cracked the large molecular particles of the asphaltene. The reduction in sulfur content under US was much greater than under MW. At all time durations, sulfur content fell as radiation time increased. Due to its high potential to absorb MW, creates active sulfur that can be emitted from the crude oil as sulfide and hydrogen sulfide, with the sulfur level falling to 0.39%. Furthermore, US waves also reduced sulfur content to around 0.46% as the asphaltene flocks disintegrated. Reduction of sulfur content from asphaltene agglomerates under MW and US was observed using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). In addition to reducing the effect of sulfur by affecting its nitrogen and oxygen elements, irradiation also reduced the polarity of the asphaltene particles and prevented reaggregation of cracked particles. Results of SARA (saturation, aromatic, resin and asphaltene) analysis showed that asphaltene particles have a higher capacity to absorb MW than resin components, as after the amount of asphaltene components declined in the early stages of irradiation, resin components began to change, falling to 34% at 10 min. The decrease in asphaltene content in samples under US was more evident, reaching 34% at 8 min. According to Fourier transform infrared (FTIR) spectra results, MW irradiation caused cracking of large-chain molecules and drove light components from heavy crude sample. These two phenomena are a function of radiation time. The rate of cracking of heavy components was continuously greater than the rate of light components leaving the sample at early time intervals; ultimately, this resulted in an upgraded heavy oil. In some cases, despite cracking of large-chain molecules and creation of light components, the output values of light components were higher. Under US, the cracking of large-chain molecules occurred, but due to the departure of heavy components from the crude oil, peak intensities increased and the resulting crude oil had purer components. [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]

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]

Particle agglomeration can occur in heavy oil upgrading hydroprocessors due to the formation of carbonaceous mesophase, a secondary liquid phase which results from an increased rate of thermal cracking relative to the hydrogenation rate. A cold-flow slurry bubble column operated at atmospheric pressure with an internal diameter of 0.152 m was used to examine particle agglomeration behavior and the overall fluid dynamics in a gas-liquid-liquid-solid system. The experimental system consisted of biodiesel (organic continuous phase), aqueous glycerol solutions (immiscible secondary phase), glass beads and nitrogen. The impacts of the secondary liquid loading, secondary liquid viscosity, and particle diameter on the fluid dynamics were established. Particle agglomeration was studied by measuring the axial solid holdup profiles while varying the superficial gas velocity and secondary liquid loading. Enhanced particle agglomeration was observed when increasing the secondary liquid loading, based on the increased solid holdups at the bottom of the column. Three sparger designs (six-legged spider sparger, perforated plate and conical perforate plate) were compared. Following the glycerol addition, the spider sparger was less effective based on the particle sedimentation at lower liquid/solid ratios when compared to the other sparger designs. A Revolution Powder Analyzer (RPA) was also used for complementary measurements to examine whether operational difficulties due to particle agglomeration can be anticipated using a simplified system. [ABSTRACT FROM AUTHOR]

Refining of high acid crudes (HACs) is seriously limited by extensive corrosion of refinery equipment due to the presence of intrinsic naphthenic acids (NAs). Herein, in the absence of a catalyst or external hydrogen, effective removal of the NAs contained in HACs was achieved using methanol at moderate temperature and moderate pressure. Several process variables, including the temperature, crude concentration, and reaction time are explored to optimize the removal of NAs from HACs. At 250 °C, 6.4 MPa, and 33.3 wt% crude, a very low total acid number (TAN) of 0.08 mg-KOH/g-oil (96.9% reduction efficiency) with a high oil yield (95 wt%) is achieved. During the reduction of the TAN using methanol, some fraction of the resins and asphaltenes in the crude oil crack to form low-molecular-weight aromatic compounds. Compared to deacidification using methanol, pyrolysis (without methanol) results in a much lower TAN reduction efficiency (38.6%). The major deacidification mechanism using methanol is esterification, while that of pyrolysis (without methanol) is decarboxylation. [ABSTRACT FROM AUTHOR]

Wilbur Nelson introduced the concept of complexity factor in the 1960s to relate the performance level of refineries with different capabilities and processing technologies. Refinery complexity has been used for many years to describe the sophistication and capital intensity of refineries, but foundational issues and the limitations associated with the metric have not been examined. A more precise and rigorous approach to complexity factors is presented based on the application of cost functions. Two alternative formulations are introduced and compared to the traditional approach and lead to new descriptive statistics and insight. [ABSTRACT FROM PUBLISHER]

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]

In this research, hydrogen induced cracking (HIC) behavior of an API X70 pipeline steel has been studied. In order to create HIC cracks, an electrochemical hydrogen charging experiment was carried out on X70 steel by using 0.2 M sulfuric acid and 3 g/l ammonium thiocyanate for 8 h. Moreover, SEM, EDS and EBSD techniques were used to characterize the as-received (AR) steel and investigate the different aspects of HIC phenomenon as well. The results showed that the inclusions and precipitates which play a key role in HIC phenomenon have been distributed randomly through the cross-section of tested steel. However, the concentration of them was higher at the center of cross-section than other areas. All HIC cracks initiated and propagated through the center of thickness where center segregation of elements has occurred. It is also observed that HIC cracks were initiated from several special types of inclusions and precipitates such as manganese sulphide and carbonitride precipitates. EBSD results showed that the dominant local texture of center of thickness in RD-TD plane was {001}//ND and {111}//ND. Moreover, HIC cracks propagate through differently oriented grains where the local texture is random. [ABSTRACT FROM AUTHOR]

Gasification is a thermochemical process that converts carbon-based fuels into a clean synthesis gas (so-called syngas). The produced syngas can be used directly as a fuel to produce electricity in gas engines or an intermediate chemical for production of Dimethyl ether (DME), methanol (MeOH), and/or ethanol. In this work, an unsteady-state, kinetic model that is used to predict the gas composition and performance indicators in presence of dolomite was developed. Results showed a good performance for biomass gasification in presence of dolomite as a catalyst. It is also concluded that the tar destruction ratio (TDR) exhibits an increasing trend with increasing [CaMg (CO3)2]/[C] from 0.1 to 0.9 (mg/mg), while after that, the increase levels off. [ABSTRACT FROM AUTHOR]

In this paper, a finite element model to analyze the cracking process of a steel fiber-reinforced concrete ( SFRC) beam on grade, loaded in two points, is presented. Already validated in the past, the numerical model used is a probabilistic explicit cracking model. The motivation of the present work is to evaluate the influence of the degree of redundancy of the mechanical system on the mechanical behavior of the beam (bearing capacity and cracking process). The main conclusion of this work is that for analyzing and properly designing SFRC structural members on grade, the only relevant tool is the finite element method using a cracking model. [ABSTRACT FROM AUTHOR]

A detailed description of the preparation and management of reliable and safe corrosion laboratory experiments requiring the presence of hydrogen sulphide (H2S) is reported in this work. The adopted method is based on a modified Kipp's apparatus allowing to produce on demand just the amount of H2S required for electrolyte saturation. Two benchmark corrosion cases were studied: electrochemical corrosion, monitored by means of potentiodynamic measurements, and sulphide stress corrosion cracking tests, both in H2S-saturated acidic aqueous chloride solutions. The sensitivity to H2S corrosion of a few classical materials of interest in the oil and gas sector, corrosion-resistant alloys, was then examined, proving as the presence of H2S leads to a denobling effect, increases the passive current density and influences significantly the time of cracking in the sulphide stress corrosion cracking tests. [ABSTRACT FROM AUTHOR]

Heavy oil is less expensive than light crude oil, but heavy oil is more expensive to obtain light oil products. Conventional light crude oil resources are decreasing, therefore heavy oil resources will be needed more in the future. There are huge differences from field to field for heavy oil deposits. In terms of final productive use, heavy oil is considered as an unconventional resource. Heavy oil upgrading depends on four important factors: catalyst selection, heavy oil classification, process design, and production economics. Heavy and extra-heavy oils are unconventional reservoirs of oil. Globally, 21.3% of total oil reserves are heavy oil. Heavy oil is composed of long chain organic molecules called heavy hydrocarbons. The thermal degradation of the heavy hydrocarbons in heavy oil generates liquid and gaseous products. All kinds of heavy oils contain asphaltenes, and therefore are considered to be very dense material. The most similar technologies for upgrading of heavy oils are pyrolysis and catalytic pyrolysis, thermal and catalytic cracking, and hydrocracking. The amount of liquid products obtained from pyrolysis of heavy oil was dependent on the temperature and the catalyst. Pyrolytic oil contains highly valuable light hydrocarbons as gasoline and diesel components range. The constant increase in the use of crude oils has raised prices of the most common commercial conventional products and consequently seeking for new alternative petroleum resources, like some unconventional oil resources, becomes an interesting issue. The mass contents of gasoline, diesel, and heavy oil in the crude oil are 44.6%, 38.3%, and 17.1%, respectively. The gasoline yield from the heavy oil catalytic (Na2CO3) pyrolysis is higher than the diesel efficiency for all conditions. The yield of gasoline products increases with increasing pyrolysis temperature (from 230°C to 350°C) and percentage of catalyst (from 5% to 10%). The yields of gasoline-like product are from 21.5% to 39.1% in 5% catalytic run and from 32.5% to 42.5% in 10% catalytic run. The yields of diesel-like product are from 9.3% to 29.8% in 5% catalytic run and from 15.5% to 33.7% in 10% catalytic run. [ABSTRACT FROM AUTHOR]

Vacuum residue cracking has been successfully conducted under supercritical water condition in presence of various metal oxide nanocalysts, namely NiO, CuO, ZnO, Co 2 O 3 , and Cr 2 O 3 synthesized at supercritical water. The cracking experiments were carried out at 450 °C. Three species of cracking: maltene, asphaltene, and coke were then weighed and their corresponding speciation was defined. Gas chromatography-mass spectrometry (GC–MS), nuclear magnetic resonance spectroscopy (NMR), thermogravimetric analysis (TGA), and elemental analysis (CHNS) tests were utilized to prove the performance of upgrading reactions. It was revealed that NiO showed the best performance among other catalyst, in which its activity and stability in catalytic cracking changed slightly. According to the results obtained from GC–MS, NMR, TGA, and CHNS anlyses, it was confirmed that the proportion of heavy hydrocarbons of products (i.e. non-catalytic and catalytic reactions) was lower than that of feedstock. [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]

Heterogeneous Brønsted acid catalysts are tremendously important in industry, particularly in catalytic cracking processes. Here we show that these Brønsted acid sites can be directly observed at natural abundance by 17O DNP surface-enhanced NMR spectroscopy (SENS). We additionally show that the O−H bond length in these catalysts can be measured with sub-picometer precision, to enable a direct structural gauge of the lability of protons in a given material, which is correlated with the pH of the zero point of charge of the material. Experiments performed on materials impregnated with pyridine also allow for the direct detection of intermolecular hydrogen bonding interactions through the lengthening of O−H bonds. [ABSTRACT FROM AUTHOR]

Significant amount of different maturity kerogen in Bazhenov oil-shale formation are reserves of hydrocarbons to be recovered by enhanced oil recovery methods in nearest future when the conventional oil field development drops crucially. A technology of in-situ kerogen conversion into synthetic oil in Bazhenov formation opens broad perspectives in development of Bazhenov formation, West Siberia, Russia. Laboratory investigation of in-situ kerogen conversion process in the presence of supercritical water performed on Bazhenov formation rocks is presented in this study. A feasibility of the tertiary hydrous pyrolysis hydrocarbons (HC) recovery method was accessed. Study helped to obtain reliable data to validate the numerical simulation model for that enhanced oil recovery method. First tests of hydrous pyrolysis extraction were conducted on crushed oil shale samples at temperatures of 300, 350, 400 and 480 °C and under formation pressure of 30 MPa. Liquid HC extraction from sample started from 400 °C. The secondary hydrocarbons conversion process was detected at reaction temperature of 480 °C. Second stage of laboratory tests allowed to find optimal parameters for in-situ kerogen conversion – optimal conversion temperature, time of the conversion. The experiments on Bazhenov formation cores with low kerogen maturity were conducted in closed vessel at formation pressure and in temperature range of 250–400 °С. It was found that oil synthesis starts at 300 °С. Amount of liquid products increased at temperatures above 350 °С, but the secondary cracking processes had been observed also. It was discovered that hydrous pyrolysis and cracking caused an increase in rock porosity and permeability. Results obtained in this study were used in numerical simulation. [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]

Thermal cracking of canola oil was investigated in a continuously operating pilot plant. The influence of different cracking temperatures (450 °C to 580 °C) on the product was observed with a final objective of maximizing LCO (light cycle oil). LCO can be used as diesel blend if a required quality is achieved. The pilot plant was constructed as a reaction/regeneration system with an internal circulating fluidized bed design. All experiments were conducted with canola oil at a feed rate of 2.5 kg/h. Silica sand was used as bed material. A 6-lump model was used for product characterization. The composition of gas ( C 1 – C 4 ), gasoline (saturated hydrocarbons, olefins, aromatics) and LCO (aromatics) was analyzed. In addition, the oxygen content of the liquid products was determined at cracking temperatures of 450 °C and 580 °C. The experiments show that the product distribution is heavily dependent on the cracking temperature. With increasing cracking temperature gas, gasoline and carbon oxides increase, whereas LCO, residue and coke decrease. At a cracking temperature of 450 °C 8.6 wt% gas, 21.1 wt% gasoline, 47.5 wt% LCO, 15.8 wt% residue, 3.7 wt% coke and 3.3 wt% carbon oxides are formed. The liquid product contains high amounts of oxygenates. [ABSTRACT FROM AUTHOR]

The bio-oil from rice hull fast pyrolysis was distillated under reduced pressure at 0.005 Mpa, then mixed with ethanol (2:3 by weight). The mixture was subjected to catalytic co-cracking over Ni-ZSM-5/MCM-41 molecular sieves in a fixed-bed at 500 °C and 3.75 h −1 of the WHSV. The distillation results showed the distilled bio-oil, compared with raw bio-oil, contained lower oxygen content (decreased from 45.91 wt.% in raw bio-oil to 33.74 wt.%), higher (H/C) eff ratio (0.35) and HHV value (22.81 MJ/kg). The ethanol was involved in the ketonization, esterification, aromatization and dehydration during the catalytic co-cracking of distilled bio-oil and ethanol. The Ni loaded on ZSM-5/MCM-41 molecular sieves reduced char formation compared with ZSM-5/MCM-41. The ZSM-5/MCM-41 catalyst exhibited higher activity in the esterification and aromatization, which converted acids in upgraded bio-oil to esters, aromatics or phenols. The Ni-ZSM-5/MCM-41 catalysts showed excellent activity that transformed acids to ketones by ketonization process. The 6% Ni-ZSM-5/MCM-41 catalyst performed the good activity with the minimum char formation (7.3 wt.%) and higher upgraded bio-oil (40.8 wt.%). Moreover, the acid content in the upgraded bio-oil dropped to 0.1 wt.% and the total concentration of CO 2 and CO in the gas products was 36.8 vol.%. [ABSTRACT FROM AUTHOR]

The coal cylinder models were static cracking destroyed at different rates by soundless cracking agent. The microseismic signals in the rupture process were monitored by ZDKT-1 type coal or rock dynamic disasters experimental simulation system. The authors tried to analyze the amplitude, energy and frequency-spectrum characteristics of microseismic signals during the static cracking of coal. It was found that the longitudinal cracks were more than transverse cracks after the static cracking of coal, the radial tensile stress was more obvious than the axial tensile stress. The static cracking process of coal could be divided into three stages：micro crack stage, expansion stress transfer stage and cleavage stage. With the static explosion process, the greater of the average amplitude of microseismic signals, coda wave development, and the frequency domain of signals were wider too (but dominant frequency decrease). The frequency domain of main shock and coda wave are different. It is possible to evaluate the process of the static cracking of coal seams by the amplitude of microseismic, the development of coda wave and the spectral characteristics. The microseisms signals are paroxysmal, the amplitudes and energies of microseismic signals in the static cracking process do not change monotonically, but show volatility changes. The numbers of microseismic events are related to the macro crack areas. It is possible to evaluate the permeability improvement effect in the process of the static cracking of coal seams by microseismic count. [ABSTRACT FROM AUTHOR]

The artificial neural network provides an effective way to handle a non-linear and strong coupled reaction system because of its strong nonlinear prediction and self-learning ability. A 19–24-4 type of back propagation (BP) neural network that can predict the product distribution of a fluid catalytic cracking maximizing iso-paraffin unit was established using 19 input variables including properties of feedstock and regenerated catalyst and operating variables. The influences of the operating variables on product distribution were simulated, and the operating variables were optimized to maximize gasoline (GS) yield by a genetic algorithm. The predicting results agreed well with the industrial data, and a significant improvement in the GS yield was gained. [ABSTRACT FROM PUBLISHER]

New possibilities for the utilization of associated petroleum gases (APG) and monetization of small-scale and remote Natural Gas resources by power generation and chemicals production are considered and tested. One possibility is the oxycracking of APG. This technology allows selective transformation of heavier hydrocarbons that have low octane (methane) numbers and inclined to soot and tar formation, into lighter compounds with higher octane numbers, thus producing gas suitable to feed different types of power engines. Another possibility is the small-scale conversion of APG to syngas to produce more easily transportable and more valuable chemicals or liquid fuels via well-known Fischer-Tropsch process or catalytic synthesis of methanol. For this purpose we have suggested principally new technology for natural gases conversion into syngas, based on the use of 3D (volumetric) matrixes. It allows the relative simple and very compact non-catalytic reformers to be designed for small-scale gas-to liquid (GTL) technologies. Their main advantages are autothermal character of the process without any need in additional heating or power supply, absence of catalyst that allows processing hydrocarbon gases of practically any composition, including APG, without additional pretreatment, very high specific volume capacity, at any rate 10 times higher than that of steam reforming, and simplicity in construction and operation. [ABSTRACT FROM AUTHOR]

Based on the thermal simulation experiments of shale and crude oil samples, the amount of gas generated from kerogen and oil cracking during each geological period was calculated based on the chemical kinetic method. The results showed that the total amount of gas generated from the Niutitang Shale in Hy1 well is 49.00 m3/t, including gas generated from kerogen (17.76 m3/t) and gas generated from oil cracking (31.24 m3/t). The period of gas generated from kerogen is from the Cambrian to the Carboniferous with amount of gas generated value of 14.77 m3/t, which is mainly from the Lower Ordovician to the Middle Ordovician (510–470 Ma). The period of gas generated from oil cracking is from the Ordovician to the Triassic, and the main period of gas generated from oil cracking is from the Lower Devonian to the Upper Permian (410–250 Ma). The amounts of gas generated from oil cracking are 13.30 m3/t, 9.44 m3/t, and 3.77 m3/t in the Devonian, Carboniferous, and Permian, respectively. [ABSTRACT FROM AUTHOR]

Thermal cracking processes such as visbreaking are used in the petroleum industry to reduce the viscosity of heavy feedstocks, such as atmospheric and vacuum residues, without forming coke or unstable asphaltenes. Thermal cracking offers a potential method to reduce the viscosity of heavy oils and bitumen, enabling their pipeline transportation with less solvent addition. Viscosity is the most important property for transportation of crude oils, but this property also has a highly non-linear dependence on temperature and composition. In this work, we used a lumped-kinetic model, based on boiling point pseudo-components, coupled with a fluid property model, to correlate the viscosity of two heavy oils subjected to thermal cracking reactions at different severities, and assess the impact of the chemical transformations on the behavior of the heaviest fraction. The properties of these pseudo-components were estimated by validated correlations, and tuned with experimental values. By assuming that after the reactions these properties remained invariable in each boiling point pseudo-component, we could estimate the viscosity of the liquid products from the recombination of these individual properties using mixing rules available in literature. The results indicated that the vacuum residue fractions (>524 °C) undergo chemical transformations that alter their fluid properties. By using adjusting factors dependant on conversion, we were able to make estimations of viscosities at different temperatures with absolute average deviations lower than 25%. [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]

The effect of femtosecond laser fluence on nanostructuring of Tungsten (W) and Molybdenum (Mo) has been investigated after ablation in ethanol environment. A Ti: Sapphire laser (800 nm, 30 fs) at fluences ranging from 0.6 to 5.7 J cm −2 was employed to ablate targets. The growth of structures on the surface of irradiated targets is investigated by Field Emission Scanning Electron Microscope (FESEM) analysis. The SEM was performed for both central as well as the peripheral ablated regions. It is observed that both the development and shape of nanoscale features is dependent upon deposited energies to the target surface as well as nature of material. Nanostructures grown on Mo are more distinct and well defined as compared to W. At central ablated areas of W, unorganized Laser Induced Periodic Surface Structures (LIPSS) are grown at low fluences, whereas, nonuniform melting along with cracking is observed at higher fluences. In case of Mo, well-defined and organized LIPSS are observed for low fluences. With increasing fluence, LIPSS become unorganized and broken with an appearance of cracks and are completely vanished with the formation of nanoscale cavities and conical structures. In case of peripheral ablated areas broken and bifurcated LIPSS are grown for all fluences for both materials. The, ablated diameter, ablation depth, ablation rate and the dependence of periodicity of LIPSS on the laser fluence are also estimated for both W and Mo. Parametric instabilities of laser-induced plasma along with generation and scattering of surface plasmons is considered as a possible cause for the formation of LIPSS. For ethanol assisted ablation, the role of bubble cavitation, precipitation, confinement and the convective flow is considered to be responsible for inducing increased hydrodynamic instabilities at the liquid-solid interface. [ABSTRACT FROM AUTHOR]

Three-dimensional computational fluid dynamics simulations were performed to study gas flow, heat transfer, and catalytic reactions of vacuum gas oil inside spherical and ellipsoidal clusters consisting of fluid catalytic cracking catalyst particles. Simulation results with respect to gas flow inside the cluster and convective heat transfer between the gas and catalyst particle agreed well with results from the literature. Simulation results indicated that the gas stayed longer and had a higher temperature inside the cluster than that in the main stream, which intensified secondary reactions of gasoline species in the gas. At a higher cluster porosity, it was predicted that the gas could flow through the cluster with lower resistance and that secondary reactions lessened. [ABSTRACT FROM AUTHOR]

Despite rigorous models of the steam cracking processes being available for simulation of naphtha cracking, the simulation is often carried out using limited characterization of such a feedstock due to unavailability of detailed composition at the time when the simulation is required. A method was developed for generation of substitute naphtha composition meeting specified properties. Sets of alternative compositions were generated, matching the density, distillation curve, and optionally PIONA of real naphtha feedstocks. Its cracking product yields were calculated using a validated cracking model. Simulated product yields were evaluated in terms of result variability and deviation from the experimental data, depending on the level of available feedstock characterization. [ABSTRACT FROM AUTHOR]

A molecular-level-process model for a fluidized catalytic cracking process was developed. The work was aimed at the coarseness of the reaction network used in traditional lumping kinetic models. A feed-component matrix containing 14692 molecules was generated using a structure-oriented-lumping (SOL) method. A total of 95 groups of reaction rules were compiled, and 702943 reactions were involved. The SOL reaction kinetic model was combined with the reactor model to calculate the temperature distribution and feedback on the complex reaction network by taking into account the reaction heats in each reaction. The model was validated by the industrial data and predicted that the gasoline yield was >51% and the olefin content in gasoline was <24% at proper operation temperatures and catalyst/oil ratios. With the aid of the molecular-level model for the maximizing-isoparaffin technology, the product distribution and corresponding product quality can be controlled rationally by manipulating the operation conditions. [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]

An internal cracking indicator is designed to quantify the risk of hot tearing in the continuous casting of round billets. For this purpose, the tensional state of the bar is acquired by implementing a thermo-mechanical model that uses a steel material law calibrated with hot tension tests. The cracking indicator is then applied to the phenomenon of diametral pinch-roll compression. Critical combinations of casting speed and steel carbon content are defined to estimate the cracking risk. At last, macro-etching is applied on industrial bars in order to reveal internal cracking, which is then compared to model results to assess its predictability. Influence of pinch-roll pressure and roll shape on the cracking risk is also analyzed. [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]

In the paper, structural changing of resin-asphaltene molecules in cracking process of oil sand bitumen are investigated. Cracking process to natural bitumen carried out in an open-to-air reactor, which extracted from oil sand by organic solvent. Reaction temperature was 450 °С and process duration was 60 min. The reactor was heated at a rate of 10 °C/min up to the desired temperature. Di-tert-butyl peroxide was used as radical formation additive. When limiting oxygen, it can be used catalyst molecule supplies as the oxidizer. The thermal destruction processes of heavy hydrocarbons with the catalyst make it possible to increase the yield of low boiling liquid products with the formation of coke and gas as by-products. High temperature leads to increase the oil content, and decrease the total resinasphaltene components in bitumen. Monte Carlo method used for construction the molecular structure of resin-asphaltene components. The calculations data determined the most stable conformation of resins and asphaltenes molecules, that the stability of the molecules affect structural characteristics such as the number of structural blocks, their size and spatial arrangement of atoms with respect to each other. Microscopic images showed that the asphaltenes have around 40‒50 nm of particle size, which large monolithic switching, weakly focused on a major surface, provided with amorphous carbon. [ABSTRACT FROM AUTHOR]

Two ferrite-austenite duplex medium manganese steels with very similar phase fractions and grain sizes were subjected to cold rolling. The 10Mn steel presented a much better cold rollability compared with the 7Mn steel, which is believed to stem from two critical factors. Firstly, the larger strain partitioning in the 10Mn steel resulted in a less deformation accommodated by the brittle δ-ferrite, which delayed or even inhibited micro-crack formation inside the ferrite phase. Secondly, the deformation twinning activated in the austenite of the 10Mn steel during rolling effectively enhanced the ductility of the austenite-martensite (γ-α′) mixed phase. [ABSTRACT FROM AUTHOR]