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Now days while the welded product of duplex stainless steels (DSS) is to be used for Cl-containing environment & sour service applications for example petrochemical, off-shore platforms, oil, gas, paper & pulp industries etc. The resistance to chloride stress corrosion cracking (CSCC) during service application has always been a threat for the manufacturer & the end user of the product. Resistance regards SCC under chloride existing environment based on current ferrite content under carefully welded duplex (ferrite-austenitic) stainless steel framework. DSS ferrite specifications required by various organizations are 30 to 60%, 30 to 70 Ferrite Number, 35 to 75%, etc. In this study, DSS 2205 material all weld metal consumable test coupons within ferrite content range 14% to 30% or 20 FN to 40 FN have been prepared & investigated. Investigations have shown that yield strength & tensile strength needs regard base metal & filler metal classifications were higher at every ferrite levels observations & no SCC cracking analyzed after 1000 hours exposure at ferrite level below 15%. [ABSTRACT FROM AUTHOR]

Because thermowells are prone to fatigue damage in petroleum cracking gas pipelines, in this paper, the LES method is used to simulate the flow around thermowells through two-way thermal-fluid-solid coupling, the internal causes of thermowell damage are explored, and measures for improving the thermowell safety are proposed. According to this study, when high-speed, high-temperature gas passes the thermocouple bushing, the main factors affecting the structural safety of the thermocouple bushing are the alternating stress caused by the vortex falling off, the thermal stress cycle due to the temperature gradient, and the pressure gradient impacted by the gas. Furthermore, this paper proposes improving the thermowell safety by installing the interference devices and optimizing the installation angle. The improvement measures were studied by conducting a two-way thermal fluid-structure coupling simulation. The results of this study show that after installing the interference device and optimizing the installation angle the displacement deformation of the thermowell and the equivalent stress is reduced by 57.2% and 72.1%, respectively, which indicates the safety improvement of the thermowell structure and the effectiveness of the method. The research contents of this paper can provide guidance for the installation and use of thermocouple bushing. [ABSTRACT FROM AUTHOR]

The article discusses issues associated with science industry. Topics discussed include antivirals as another promising route to decrease risk of Covid-19 pandemic risks alongside vaccination; joint venture technology firm created by Reaction Engines in Oxfordshire; new approach to treat Alzheimer's disease by using an engineered form of a protein associated with the disease.

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]

The article discusses the main methods of modeling processes of skew rollers. Factors influencing the formation of internal cracks are discussed. The tendency of a material to crack in skew rolling processes decreases as the temperature of material increases, the number of rolling cycles decreases, and the number of rolls increases. In two-roll skew rolling, internal cracks appear around a central axial zone of a rolled specimen. The size and density of inclusions in a metal sample directly affect the formation of internal cracks. [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]

In order to prevent the cracking of large volume marine concrete, which result in water seepage deterioration of the structure,the double-control technology (temperature field and expansion history control) with anti-cracking agent is used instead of the cooling water pipe to control large volume concrete crack. The mixing ratio is low cement dosage, high content mineral admixture and 8% anti-cracking agent. The anti-cracking agent has the effect of reducing the early hydration heat release rate,the expansion storage pre-compression stress during the temperature rise phase and the compensation for shrinkage deformation during the temperature reduction. At the same time, the work performance,mechanical properties and durability of the concrete are excellent. After the calculation and analysis of cracking risk through finite element simulation,when the length of the anti-cracking concrete is poured within 20 m, the cracking risk value is less than 0.7, and the concrete will not crack,meet design and construction requirements. [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]

Copyright of Iraq Journal of Market Research & Consumer Protection / Al-Mağallaẗ al-ʿIrāqiyyaẗ li-Buḥūṯ al-Sūq wa-Ḥimāyaẗ al-Mustahlik is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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]

Highlights • Hydrocracking and hydrotreating reactions kinetics are based on lumping technique. • The industrial model is validated with the performance of an experimental reactor. • Axial and radial dispersions are used to represent the slurry-phase reactor dynamic's. • Dynamic and steady-state simulations for hydrocracking of heavy oils are presented. • A sensitivity analysis of model parameters and operating conditions is presented. Abstract Modeling and simulation of a commercial size unit for hydrocracking of an atmospheric residue (312 °C+) in a slurry-phase reactor are reported. The model of the industrial reactor is formulated taking into account axial and radial gradients of the state variables: composition and temperature. The mathematical model was partially discretized with finite central differences in the positional derivatives generating a matrix system of ordinary differential equations which was solved by a Runge-Kutta method. The hydrocracking reaction kinetic model is based on lumping technique and hydrotreating reactions kinetics are described by Langmuir-Hinshelwood and power-law approaches. All the intrinsic kinetic parameters and correlations used in the simulations were taken from the literature. Dynamic and steady-state simulations were performed with the objective to find a distribution of composition and temperature in the reactor as a function of time. Also a parametric sensitivity study was elaborated in order to analyze the effects of uncertainties of model parameters in the dynamic and steady-state model responses. [ABSTRACT FROM AUTHOR]

The adsorption and reaction properties of heterogeneous zeolite catalysts (e.g. for catalytic cracking of petroleum, partial oxidation of natural gas) depend strongly on the types and distributions of Al heteroatoms in the aluminosilicate frameworks. The origins of these properties have been challenging to discern, owing in part to the structural complexity of aluminosilicate zeolites. Herein, combined solid‐state NMR and synchrotron X‐ray powder diffraction analyses show the Al atoms locate preferentially in certain framework sites in the zeolite catalyst Al‐SSZ‐70. Through‐covalent‐bond 2D 27Al{29Si} J‐correlation NMR spectra allow distinct framework Al sites to be identified and their relative occupancies quantified. The analyses show that 94 % of the Al atoms are located at the surfaces of the large‐pore interlayer channels of Al‐SSZ‐70, while only 6 % are in the sub‐nm intralayer channels. The selective siting of Al atoms accounts for the reaction properties of catalysts derived from SSZ‐70. [ABSTRACT FROM AUTHOR]

Body text Keywords Body text Review policy Body text Reader comments Body text Prestressed hollow-core slabs are generally precast concrete elements manufactured using an extrusion machine. Although prestressed hollow-core slabs are designed as uncracked members under service loads, cracking is unavoidable under excessive loading. The postcracking behavior of hollow-core slabs can be improved at very low cost by adding structural macrosynthetic fibers during the casting process with no modifications to the mixture proportions of zero-slump concrete. This paper examines the behavior of structural macrosynthetic fiber-reinforced hollow-core slabs at three different shear span-to-depth ratios a/d. Six full-scale tests were conducted on hollow-core slabs, of which three had no fiber additives and three had a polyolefin fiber dosage of 0.33%. The a/d values of 2.5, 3.75, and 7.5 were considered to evaluate the effect of macrofibers on the performance of hollow-core slabs. The test results indicate that the addition of macrosynthetic fibers increased the ultimate strength up to 19% with an increase in ductility. The contribution of fibers in improving the postcracking stiffness was better at higher a/d values under flexure-dominant behavior. Existing analytical models were suitably modified to predict the theoretical capacity of slabs with and without fibers. [ABSTRACT FROM AUTHOR]

Body text Keywords Body text Review policy Body text Reader comments Body text The American Association of State Highway and Transportation Officials' AASHTO LRFD Bridge Design Specifications have a refined method for the calculation of time-dependent losses in prestressing force. This method estimates a gain in the prestressing force due to differential shrinkage between the precast concrete girder and the cast-in-place deck; however, it does not consider the possibility of cracking in the deck. Some state departments of transportation believe that after the deck cracks, the gain in the prestressing force is lost, and they do not include it in the prestress loss calculations. Some other state departments of transportation believe that not all of the prestress gain is lost and allow some percentage of the gain to be retained. This study focuses on the effect of deck cracking on the long-term loss of prestressing force. A finite element software model was used to simulate three different girder lengths with varying deck concrete strengths, differential shrinkage parameters, and girder ages at the time the deck was placed. When the girder age at the time of deck placement is more than 60 days, there is a high probability that the deck will crack, though a deck placed on a girder of any age may crack, depending on the properties of the deck and girder. When the deck cracks, some of the gain of prestressing force is lost, but the percentage lost depends on the extent of cracking in the deck. The older the girder is when the deck is placed, the greater the cracking. The cracked deck still provides some restraint, and even in cracked decks, nearly 50% of the prestress gain due to differential shrinkage was retained. [ABSTRACT FROM AUTHOR]

Highlights • Effect of wall-effect, and fibre orientation and content on tensile strength of SFRC. • MCST is a multi-axial cube splitting test used to get post-crack properties of SFRC. • An approach for the determination of fibre orientation using MCST is proposed. • MCST method was verified to be a good method of determining the orientation of fibre. Abstract The post-cracking behaviour of steel fibre reinforced concrete (SFRC) are significantly influenced by the distribution of steel fibre in the concrete, while steel fibre distribution is further affected by wall-effect and fibre content. A series of three-point bending tests, cube splitting tests, and Brazilian splitting tests were conducted to analyze the influence of wall-effect and fibre content on the post-cracking tensile strength of SFRC. Furthermore, the influence of wall-effect and fibre content on fibre distribution was determined by conducting inductive tests on cubic SFRC specimens. To directly determine the relationship between fibre content and orientation, and the post-cracking mechanical properties of SFRC, this paper proposes a multi-axial cube splitting test (MCST test). Furthermore, this paper also proposes a method which utilizes the MCST test to measure fibre orientation based on the relationship between post-cracking peak load and toughness, and steel fibre orientation. Therefore, MCST method can be adapted for using with any type of fibre reinforced concrete, while the inductive test can only be used for concrete that is reinforced with metallic fibre. The MCST method is verified by comparing the similarity of the fibre orientations that were obtained using the inductive tests and MCST tests. [ABSTRACT FROM AUTHOR]

A new theoretical and practical framework has been developed through operando study of the zeolite catalytic cracking of low‐density polyethylene (as a model reaction) under reaction conditions. Results show that microporous ZSM‐5 gives rise to less cracking products. Hierarchical ZSM‐5 zeolites are more active cracking catalysts, rendering more C2‐C5 hydrocarbons, with a delayed deactivation due to the secondary porosity. This tool in combination with thermogravimetric analysis provides complementary and valuable information for the study, and design of advanced catalysts. A cracking catalyst: Operando study provides valuable information about how the ZSM‐5 catalyst works under reaction conditions for the low‐density polyethylene cracking. This study illustrates that microporous ZSM‐5 gives rise to less cracking and deactivates faster, whereas hierarchical ZSM‐5 cracking catalysts are more active with delayed deactivation due to the secondary porosity. [ABSTRACT FROM AUTHOR]

Highlights • A novel hierarchical millisecond gas-phase catalytic cracking process was proposed. • Five catalysts were compared to study the selectivity of C 2 -C 4 hydrocarbons and BTX. • The maximum light olefins yield was obtained with 30% calcium aluminat/70% ZSM-5. • A bench-scale was used to verify the potential application of VR to chemicals. Abstract In order to enhance the production of light olefins from vacuum residue (VR), a novel hierarchical millisecond gas-phase catalytic cracking (HM-GCC) process was proposed. The process integrated the pyrolysis of VR and the catalytic cracking of the pyrolysis oil in the gas phase. Firstly, the effects of reaction temperature on the millisecond pyrolysis behavior of VR were investigated, and the results showed that the increase of C 2 -C 4 hydrocarbons content was not obvious when increasing the temperature from 600 to 750 °C. However, the thermal cracking as a pretreatment process converted the VR macromolecule into the low molecular pyrolysis oil. After that, five different catalysts calcium aluminate, FCC catalyst, and ZSM-5 zeolites (Z-40, Z-80, and Z-200) were investigated to evaluate their activities in catalytic cracking of pyrolysis oil, and among them Z-40 showed the highest selectivity for C 2 -C 4 hydrocarbons and BTX. For further study, the relative contents of C 2 -C 4 hydrocarbons were higher for the combination of calcium aluminate and Z-40 (Z + C-cat) than that of the pure Z-40 catalyst. This result was attributed to the fact that Z + C-cat facilitated the cracking of macromolecules and inhibited hydrogen transfer reactions. Finally, the conversion of VR and pyrolysis oil was studied in the bench scales with calcium aluminate and Z-40 catalyst. The yield of ethylene, propylene and butenes increased by 4.69, 7.87 and 3.37 wt% respectively in the presence of Z-40. [ABSTRACT FROM AUTHOR]

Highlights • Enhancing cracking process based on synergy improvement among radial field profiles. • Quantitatively analyzing the suitable arrangement of internals based on fluid mechanics principle. • A novel concept of mass transfer synergy angle was derived to explain the mass transfer enhancing mechanism. Abstract A novel insert-hollow cross disk (HCD) combined with twisted tape is embedded in a cracking coil to enhance the propane cracking process by positive constructing of synergetic flowing field. Quantitative analysis of appropriate insert arrangement has been conducted based on contrastive CFD simulation results in the bare and novel coil. The characteristic exchanging flow between the central zone and the near wall area induced by inserts in the novel coil can play an effective role in improving the radial synergy among heat, mass and velocity. This leads to an obvious yield increase of 0.50% and 10.23% of ethylene and propylene comparing with the bare coil. And the average tube skin temperature is declined by 28.45 k. Moreover, the Nu and Sh are increased by 10.96% and 2.98% respectively and the overall PEC factor has a rise of 8.00% in the novel coil. This confirms the effective strengthening effect by the novel coil. Furthermore, the field synergy theory is applied to evaluate the synergy improvement for the heat and mass transfer process. Comparing with the bare coil, the synergy angles for heat as well as mass transfer in the novel coil have a maximum decrease of 21.76% and 23.14% in the downstream of the twisted tape (z/L = 0.23) and HCD insert (z/L = 0.60), respectively. This could explain the enhanced heat and mass transfer as well as the product distribution due to the synergic flow field in the novel coil with the assemble inserts group. [ABSTRACT FROM AUTHOR]

Highlights • A new six-lump kinetics scheme was developed. • New six-lump activation energies, frequency factors and heat of reactions developed. • The estimated parameters can be used to simulate any type of FCC riser. Abstract In this work a simulation of detailed steady state model of an industrial fluid catalytic cracking (FCC) unit with a newly proposed six-lumped kinetic model which cracks gas oil into diesel, gasoline, liquefied petroleum gas (LPG), dry gas and coke. Frequency factors, activation energies and heats of reaction for the catalytic cracking kinetics and a number of model parameters were estimated using a model based parameter estimation technique along with data from an industrial FCC unit in Sudan. The estimated parameters were used to predict the major riser fractions; diesel as 0.1842 kg-lump/kg-feed with a 0.81% error while gasoline as 0.4863 kg-lump/kg-feed with a 2.71% error compared with the plant data. Thus, with good confidence, the developed kinetic model is able to simulate any type of FCC riser with six-lump model as catalyst-to-oil (C/O) ratios were varied and the results predicted the typical riser profiles. [ABSTRACT FROM AUTHOR]

Highlights • The two breakdown types of coal by HVEP in air environment were found. • Liquid nitrogen adsorption, SEM and 3D-XRM results suggest that HVEP is a potential method for CBM extraction. • A new method for fracturing and permeability enhancing is proposed combining with the hydraulic fracturing and HVEP. Abstract In order to enhance the gas extraction rate of low-permeability coal seams, a study was made on variation characteristics of pore structure of the coal saturated by NaCl solution under the effect of high-voltage electrical pulses (HVEP) by adopting a self-designed experimental system of fracturing and permeability enhancing of the coal with HVEP. In addition, current waveforms in the process of electrical breakdown were also investigated. The results revealed the two types of electrical breakdown of the coal in air environment, namely, surface breakdown and internal breakdown with three forms of breakage, namely, complete comminution, breakage from one side and cracks on the surface. Furthermore, the coal was broken due to internal tension under the influence of HVEP. Based on energy dispersive spectroscopy (EDS) analysis, the coal underwent both physical and chemical changes where the current flowed. Results of scanning electron microscope (SEM) demonstrated that the higher the breakdown voltage, the more the fissures in coal, and the better the breakage effect. Fissures in the coal were observed via the 3D-XRM to extend radially from the center to boundary areas with the breakage effect weakening gradually from anode to cathode when needle electrode discharged. Besides, these fissures were interconnected with each other. The result of liquid nitrogen adsorption suggested that electrical breakdown could effectively boost gas desorption by improving fissures as well as pores and micropores in the coal. Characteristics of the current waveform showed that great thermal expansion stress was caused by huge energy injected into the coal in an instant. During the electrical breakdown of coal with the same voltage, the peak current was different which increased with the growing of breakdown voltage. [ABSTRACT FROM AUTHOR]

Abstract The main purpose of this study is to elucidate the effect of catalyst on asphaltene molecular structure during hydrocracking of C 5 -isolated asphaltene. Remained asphaltene and coke were obtained after hydrothermal and catalytic hydrothermal cracking of C 5 -isolated asphaltene at 380–430 °C, using 1000 ppm Mo from Mo-octoate precursor. XRD and NMR analyses were used to investigate the change of molecular structure of asphaltene during the reaction. It was revealed that aggregation of asphaltene increased with increasing the reaction severity resulted in coke formation. The presence of catalyst reduced the aggregation of asphaltene molecules in comparison with the hydrothermal cracking. It was also observed that the average number of stacked polyaromatic sheets in the remained asphaltene decreased with increasing the reaction temperature because of the transformation of high stacked asphaltene into coke during the reaction. Moreover, it was confirmed that the main reason for asphaltene aggregation was the reduction of steric hindrance of asphaltene molecules by the change in molecular structure of asphaltenes. [ABSTRACT FROM AUTHOR]

Purpose The purpose of this paper is to solve the tubing corrosion problem of B Block on the Right Bank of Amu Darya river sour gas field.Design/methodology/approach By using four-point-bending method, the tubing's ability to resist sulfide-stress cracking was tested. Simulating the wellbore corrosive environment, the corrosion inhibitor which was suitable for gas filed had been screened. According to the characteristic of Amu Darya river gas field, the corrosion monitor system had been designed.Findings From the feedback of wellbore corrosion monitor result, the corrosion rate was lower than 0.076 mm/a.Originality/value This anti-corrosion technique provides security for the development of gas field. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Development of a novel cracking catalyst for deoxygenation from earth abundant kaolin. • Characterization of the deoxygenation active sites on catalyst for the first time. • Correlation of the catalyst deoxygenation ability to its density of weak Lewis acids. • Study of the effects of density of Bronsted acids on triglyceride dehydrogenation. • The total amount of Bronsted acids determines the cracking capability of a catalyst. Abstract This work presents a cost-effective abundant kaolin-based cracking catalyst that has high deoxygenation, mild cracking, and low dehydrogenation performances for waste cooking oil (WCO) upgraded into organic liquid products (OLPs). Acid treated kaolin (ATK) exhibited high yield of 74.4% and high quality liquid products with high oxygen removal of 93.8% and low aromatic contents of 22.5%. The reference catalyst, a commercial petroleum catalyst (CC) could eliminate the most of oxygen (90.8%) but produced too many unexpected aromatics (55.8%). The density of weak Lewis acids was related to the deoxygenation capability. The density of Bronsted acids contributed to hydrogen transfer reactions. The total amount of Bronsted acids was correlated to cracking capability. The cracking by CC primarily followed carbonium ion reaction mechanism, whereas those by the kaolin-based catalysts complied more with free radical reaction mechanism. The deoxygenation active sites were characterized by CH 3 COOH-TPD for the first time. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Heat transfer performance is investigated at the presence of hollow-cross disk as a vortex generator for the cracking coil. • The vortical flow induced by HCD couples with CVPs and hairpin-like vortex, efficiently enhancing the heat transfer locally and globally. • The heat transfer mechanism is studied by field synergy theory, which indicates superior synergy near the wall weighs higher for the cracking flow. Abstract A novel comprehensive vortex generator, hollow-cross disk (HCD) which comprises a special sinusoidal wave structure, has been proposed to modify the configuration for cracking coil. The effects of HCD on the turbulent flow patterns, heat transfer characteristics and micro-mixing efficiency of the flow are investigated by CFD modelling in the present work. The numerical results demonstrate that in the test range of flow rates, the vorticial flow induced by HCD couples with CVPs and hairpin-like vortex, efficiently enhancing the convective heat transfer locally and globally. In contrast, although the global swirling flow induced by a twisted-tape can enhance the turbulence intensity, larger pressure drop taking place in the coil leads to relatively poor comprehensive heat transfer performance and lower micro-mixing efficiency. Moreover, the mechanisms of heat transfer enhancement for the cases with inserts have been investigated by the synergy regulation and the synergy between the temperature gradient and velocity has been discussed. The results indicate that better synergy occurring in the vicinity of coil surface is a key factor to enhance heat transfer for the cracking process. The obtained results can be used as a guidance for the design and optimization of the inserts for the cracking process. [ABSTRACT FROM AUTHOR]

A new approach to improve the gasification process was studied through the development of an automatic shaking grate mechanism in a single stage downdraft gasifier. Tar and ash build-up are problems commonly encountered during the gasification process. This study was conducted to mechanically induce tar cracking, to prevent blockages of biomass materials at the hopper as well as to ease the removal of ashes during the gasification process. It applies the principle of increasing the effective area for tar cracking at elevated temperatures to improve the amount of combustible producer gas as well as the conditions for thermal tar cracking. Experiments were done at varying air flow rates to evaluate different gasification parameters in comparison to conventional downdraft gasifier. The study resulted to 74% reduction in tar content, 30% improvement in high heating value and 27% increase in efficiency compared to the conventional downdraft gasification at 160 Lpm air flow rate. [ABSTRACT FROM AUTHOR]

Abstract The paper examines the proposed approach of using T-matrix model to convert dynamic moduli (Young's modulus and Poisson's ratio) determined by sonic well logging to values equivalent to values of static moduli (called effective moduli). The chosen approach is particularly suitable for rock masses consisting of solid rocks with irregular local cracking. The proposed approach is based on the fact that for intact rock with Young's modulus values on the order of several tens of GPa and strength σ c on the order of several tens of MPa, the values of static and dynamic moduli are equivalent. Any fractures in the rock will cause the elastic behaviour to cease being linear and a difference will appear between the values of static and dynamic moduli. It is possible to approximate this difference using the T-matrix model. The starting point for creating a T-matrix model is a simplified layered geological model of a borehole profile. Added to this are values of static moduli determined by a uniaxial compression test on representative samples of the borehole core. Additional input data for calculating the T-matrix model include porosity determined from well logging measurements, and the presence of cracks as interpreted from an acoustic scan of the borehole wall. The given approach is demonstrated in the experimental measurement of a borehole in Silurian limestone. The procedure was verified by comparing the calculated effective moduli with values of static moduli, measured on control samples prepared from borehole core outside the collection intervals of samples used as input for calculation of the T-matrix model. This comparison showed that for majority of samples there was a decrease in the difference from nearly 40% (dynamic moduli) to under 10% (effective moduli). Highlights • Use of a T-matrix model made it possible to approximate static moduli from dynamic moduli. • The curves calculated by the model are significantly more detailed than the original well logging. • The calculated effective values can be used for calculations instead of the static values. [ABSTRACT FROM AUTHOR]

Highlights • Large number of scenarios (10) shows impact of various practical variations. • Broad bandwidth of production cost; choice of vegetable oil being the most decisive. • Power-to-gas adds 26–34% to costs compared to conventional hydrogen provision. • High cracking rate for jet leads to high production of low-value hydrocarbons. • Diesel-mode is 30% cheaper than jet-mode. Abstract A techno-economic assessment of a novel biorefinery concept is carried out. It combines the hydrotreatment of vegetable oils (HEFA) with a power-to-gas (PTG) unit that provides the required hydrogen. Several scenarios are examined: the electricity supply for the PTG unit is varied from a grid-based supply to a renewable island solution; the hydrogen supply is varied from a PTG unit to conventional steam reforming; the utilised vegetable oil is varied from jatropha to rapeseed, palm and used cooking oil; the main product is varied from jet fuel to diesel. The HEFA-plant is assumed to process 500 kt of vegetable oil annually. In the reference scenario, jatropha oil is used as feedstock producing 227 kt a−1 of jet fuel. Per ton of processed oil, 1910 kWh el are used to produce 35.7 kg of hydrogen required for its treatment. By using different vegetable oils, both hydrogen demand and fuel output vary in a range of about ±10%. The overall energetic efficiency towards jet fuel is 41.6%. With a bandwidth between 1295 and 1800 EUR t−1 of jet fuel, the specific production costs are three to four times higher than the market price for fossil jet fuel. Operating the refinery in diesel-mode could lower the production costs by ca. 30%. More high-value, long-chained fuels are produced this way due to a lower cracking rate compared to the jet-mode. Investments of around 132 million EUR are required for the HEFA-plant in all scenarios. Investments for the PTG-plant lie around 82 million EUR if there is a constant electricity supply from the grid. They reach 246 million EUR if electricity is supplied in an island-solution based on fluctuating renewables demanding much higher hydrogen production and storage capacities. Total investments in the biorefinery reach 378 million EUR in this case. Despite high capital costs, the largest cost item is vegetable oil – similarly to a conventional HEFA plant. Supporting policy instruments such as subsidies or quotas for renewable jet fuel seem indispensable for an introduction of the PTG-HEFA technology in the short to medium term. [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]

Steam cracking is a fundamental application of olefin production which is the building block of petrochemical complex. Continuous efforts are being made to optimize the cracker performance by process-side optimization. The cracker furnace flue gas, which has a huge quantum of low-grade energy, is getting lost from the stack; a waste heat recovery system is being employed to generate ow-pressure steam. This also helps in the reduction of induced draft fan suction temperature. However, if there are no low-pressure steam consumers, the steam requires to be vented or partial heat recovery to be done. The lower heat recovery through waste heat recovery boiler restricts the cracking furnace throughput due to a higher suction temperature of the induced draft. A detailed steam network study has been done for a petrochemical complex having various downstream plants to maximize heat recovery as well as furnace throughput. For any equipment in question, to use a lower steam, it was a challenge to switch over from relatively higher-pressure steam to lower-pressure steam due to equipment design consideration as well as operating temperature requirement of any process. Different alternatives were thought of and evaluated based on process requirement, possibility of steam venting of other level steam, and cost of modifications. The outcome of this study has helped to utilize the low-pressure steam. The study indicated that for optimization of cracker performance, in addition to process side, there is a scope to improve on flue gas side operation also. [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]

Abstract Steam crackers convert hydrocarbon feedstock (e.g., natural gas liquids) to light olefins via thermal cracking and produce hydrogen as a by-product during the process. Benefiting from the shale gas boom in recent years, the overall production capacity of U.S. steam crackers, as well as the potential of by-product hydrogen production, is continuously growing. We estimate that 3.5 million tonne/year of by-product hydrogen can be produced from steam crackers, almost doubling the size of the existing U.S. merchant hydrogen market. We also find that producing hydrogen from steam crackers creates less (15%–91%) life-cycle greenhouse gas emissions than the conventional centralized steam methane reforming (SMR) pathway. For criteria air pollutants, life-cycle emissions reduction benefits vary greatly (−75% – +85%), depending on the co-product treatment scenario (substitution or allocation) and air pollutant type. The substitution scenario generally results in an increase of criteria air pollutants emissions, mainly due to the requirement of substitutive natural gas fuel. We estimate that the cost of purified by-product hydrogen fuel from steam crackers is $0.9–1.1/kg, reducing hydrogen production costs by 30% compared to the conventional central SMR pathway. Furthermore, using by-product hydrogen from steam crackers can generate credits of $1.8–2.5/kg under California's low-carbon fuel standard. Graphical abstract Image 1 Highlights • By-product hydrogen production capacity from steam crackers: 3.5 million tonne/year. • Cost of by-product hydrogen from steam crackers is lower compared to steam methane reforming. • Different co-product allocation methods (mass and market value) are evaluated. • Using by-product hydrogen from steam crackers provides greenhouse gas emission reductions. • Criteria air pollutants emission reduction benefits depend on allocation approach. [ABSTRACT FROM AUTHOR]

It is important to develop new promoters of fluid catalytic cracking (FCC) catalyst to increase iso-paraffin yield and avoid the decrease of research octane number (RON) caused by olefin saturation in gasoline hydrofining. SAPO-11 and LaAPO-11 molecular sieves were used as promoters to FCC catalyst to increase gasoline RON and were tested in the cracking reaction of n-dodecane on FCC conditions. LaAPO-11 molecular sieve has less and weaker acidity than SAPO-11 molecular sieve. LaAPO-11’s metallic sites polarize the C H bonds to form carbenium ions for isomerization reaction and weak acid sites make less contributions to the cracking of iso-paraffin. LaAPO-11 promoter increases the yield of iso-paraffin (C 5-9 ) from 6.4% to 10.2%. Besides that, a high yield of arene (2.0%) is caused by the dehydrogenation activity of LaAPO-11 promoter. The new contributions of this paper are the synthesis of a hydrothermal stable LaAPO-11 molecular sieve with isomerization activity and proposing the reaction routes of iso-paraffin. These new contributions are important for developing more effective RON promoters of FCC catalyst. [ABSTRACT FROM AUTHOR]

The tension test was used for studying the effect of stress variance on stress corrosion cracking susceptibility of low carbon steel immersed in 0.1 M of the sulphuric acid solution. Three unequal values of stress applied on three similar specimens after preparing and grinding them in three metal frames that were manufactured for this purpose were used for 30 days of exposure. The stress increased and the acidic solution effect caused more corrosion and cracking so, the weight loss was more. The relation between stress and weight loss variance was approximately linearly dependent. The corrosion rate was calculated using the weight loss method, and its value was also increased because of the increase of weight loss. The sulphuric acid solution was a good corrosive medium for low carbon steel because of the high percentage of Iron (Fe) which is approximately 98, and a low percentage of Cr and Mo minerals. [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]

In this research, a global reaction model for the thermal cracking of China No.3 aviation kerosene was modeled based on experimental investigations under supercritical pressure. The result indicates that, when the conversion is lower than 50%, small molecules of products were generated nearly in a constant ratio and the selectivities of them were approximately identical. Therefore, a molecular kinetic model was developed using plug flow reactor model and an isothermal hypothesis. In order to estimate the kinetic parameters, a novel method of online density measuring was used to obtain the precise resident time. The reliability of this molecular kinetic model was validated through the comparison of experimental results with simulated values. [ABSTRACT FROM AUTHOR]