Mechanism Of Deposit Formation Research Articles

Electrochemical Preparation and Characterization of Mn5O8 Nanostructures

Electrochemical synthesis followed by heat-treatment is a facile and easy method for preparation of nanostructured metal oxides. Herein we report nanostructured Mn5O8 prepared through pulse cathodic deposition followed by heat-treatment for the first time. For the preparation of Mn5O8 nanorods, pulse cathodic electrodeposition was first done from 0.005M Mn(NO3)2 at the current density of 5 mA cm-2 which yield Mn3O4 precursor. Then, heat-treatment of the deposited precursor was performed to obtain final Mn5O8 product. The structural and morphological properties of the prepared product were investigated by XRD, FT-IR, SEM and TEM techniques. The analysis results revealed that the prepared sample has pure Mn5O8 composition with rod morphology at nanoscale. Mechanism of deposit formation during pulse deposition was proposed and discussed. The formation of Mn5O8 nanorods via calcination of Mn3O4 precursor was also studied by thermogravimetric analysis. The results suggested that the cathodic electrodeposition-heat treatment method can be considered as simple and facile route for preparation of Mn5O8 nanorods.

The effect of antioxidant additives on the growth of deposits on the use of biodiesel fuel (B100) at certain temperatures

Indonesia and several tropical countries produce a lot of energy sources including palm oil, coconut, nyamplung, rubber seeds, kosambi and various other plants. The source can be converted into biodiesel or bioethanol. This is reinforced by Regulation of The Minister of Energy and Mineral Resources, the government issued Indonesia’s National Energy Policy under Regulation of The Minister of Energy and Mineral Resources of The R.I. No. 12/2015. This regulation formalized the promotion of biofuels in Indonesia, for both ethanol and biodiesel, and established a 30% biofuel in national energy consumption mandate by 2025. However, consideration of the use of biodiesel fuel is the formation of deposits in the engine or combustion chamber. In this study, the formation of a deposit of biodiesel fuel was carried out by comparison of biodiesel B100-NA without additive with biodiesel variation plus antioxidant additives such as B100 + BHT, and B100 + PG performed by the method of fuel droplet to heat plate to know the characteristics and mechanism of deposit formation On each fuel variation. The research was conducted by the deposition process and evaporation of Diesel fuel which was repeatedly carried out on a hot plate. The plate is heated with temperature variations in the enclosed space so that the conditions are close to the real condition of the engine. This test uses hot room temperature test rig. Use of antioxidant additives to inhibit oxidation in biodiesel is expected to keep the acid number low and increase oxidative stability, which will help prevent excessive deposits in the combustion chamber. This study aims to find the optimal temperature for the growth of the deposit can be controlled.

Ore-forming fluid system of bauxite in WZD area of northern Guizhou province, China

The ore-forming fluid system of bauxite in Wuchuan-Zheng,an-Daozhen (short for WZD) Area of northern Guizhou Province was studied from the perspective of deposit formation mechanism. It was discovered that ore-forming fluids were mainly effective for transporting and leaching during the formation of bauxite. The means of transport mainly included colloidal transport, suspended transport and gravity flow transport. In the course of their leaching, fluids had a range of chemical reactions, as a result of which elements such as silicon and iron migrated downwards. In this process, properties of fluids changed as well.

Depressurization and boiling of a single magmatic fluid as a mechanism for tin-tungsten deposit formation

Depressurization and boiling of a single magmatic fluid as a mechanism for tin-tungsten deposit formation

Influence of fat and oil type on the yield, physico-chemical properties, and microstructure of fat, oil, and grease (FOG) deposits

Fat, oil, and grease (FOG) deposit, in the form of calcium soap, was found to cause sanitary sewer overflows due to its adhesion on pipe walls. To address this problem, laboratory-prepared calcium soaps have been used to investigate the formation mechanisms of FOG deposits. However, the fats and oils previously utilized were limited and some soap characteristics were not examined. This research attempted to probe through the properties of calcium soaps prepared from calcium chloride and the fats and oils of chicken, pork, palm olein, soybean, olive, and coconut to further understand FOG formation and stability. Results revealed that FOG deposits may occur as smooth, paste-like material or coarse, semi-solid substance depending on their exposure to excess fat/oil and calcium. The smooth soaps with more excess fat/oil demonstrated high apparent viscosity and consistency index, while the coarse soaps with large levels of calcium signified higher melting endset. Moreover, a soap microstructure showing evident networks and lesser void area displayed higher heat and rheological stability, respectively. Overall, fats and oils with higher oleic to palmitic acid ratio such as palm olein oil, olive oil, chicken fat, and pork fat produced soaps with greater yield and degree of saponification. Hence, establishments and authorities should be alert in managing and monitoring these wastes. On the other hand, soybean oil high in linoleic acid and coconut oil high in lauric acid do not pose an immediate threat to the sewer system since they only produced soaps in small quantity. However, their soaps showed high melting endset which could pose a serious effect when accumulated at large amount. On the whole, the fatty acid profile of fats and oils, the presence of excess fat/oil, and calcium content mainly dictate the appearance, melting, rheology, and microstructure of calcium soaps. Their distinct properties can be used as criteria in predicting the condition and stability of FOG deposits.

Research advances in the formation poredynamics of sedimentary basins

In the 21st century, the geodynamics is developing towards quantitative researches. However, due to the irreversible geological processes, it was very difficult to recover the geological process. In particular, the restoration of geological parameter evolution process at the microscopic scale has become a major scientific problem in geology presently. Thereby, a concept of the formation poredynamics is revised and proposed, and the formation poredynamics is a fundamental discipline which focus on the mechanical characteristic of porous media, the pore evolution law, the dynamic genesis and the seepage property of pore fluid during the burial process of clastic rocks. Moreover, it is a new interdiscipline of underground diagenetic dynamics and pore fluid dynamics, and also is as an important part of sedimentary basin dynamics. Research advances were made in both basic theory and applied research. The advances in the basic theory include: (1) the static equilibrium principle of the formation pore, (2) the porosity evolution mechanism and quantitative model of sandstone during the burial diagenetic process, (3) the compaction characteristic and the porosity evolution quantitative model of mudstone, (4) the theoretical relationship between the underground pore fluid temperature and the pore fluid pressure, (5) the influence of the tectonism-induced additional geostress on the pore fluid pressure, and (6) the relationship between the mudstone compaction and the vitrinite reflectance (Ro) of organic matter. The advances in the applied research include: (1) the geotemperature-geopressure system division of the sedimentary basin and the interpretation of the hydrocarbon distribution dynamic, (2) the modification of the strata pressure prediction model, (3) the construction of the reservoir critical properties and the reservoir dynamics evaluation system, (4) the simulation of the evolution process of the formation fluid pressure, (5) the numerical simulation and physical experimental simulation on the sandstone hydrocarbon charging dynamics, and (6) the dynamic process analysis of the hydrocarbon accumulation in tight sandstone. Through the integration between the pore genesis evolution and the pore fluid dynamic evolution, the formation poredynamics is one of the representative discipline branches that the geological dynamics research had developed toward the underground microscopic scale in recently 20 years, and it also is an inevitable result from the quantitative development of the formation and distribution mechanisms of sedimentary mineral deposits. Based on the formation poredynamics research, eight important research achievements are summarized, and the geological researches are extended from the macroscopic scale to the microscopic scale, to find out the pore parameter evolution law under control of the formation pore evolution during the burial process, and update and improve exploration and production application technologies.

Protection of hot subsea risers by using thermally sprayed aluminium

PurposeIn spite of the high interest in thermally sprayed aluminium (TSA) to protect offshore structures, pipelines, risers, etc., data correlating the exposure of TSA-coated steel in hot seawater to its performance are lacking. No information is available on the performance of TSA in hot seawater, especially when damaged. This paper aims to address this knowledge gap and report the corrosion performance of damaged TSA on carbon steel exposed to boiling synthetic seawater for different periods (up to 5,000 h). It also attempts to understand the mechanism of formation of calcareous deposits in boiling synthetic seawater by using various characterisation tools.Design/methodology/approachTwin wire arc spray was used to coat carbon steel specimens with commercially pure aluminium. Holiday was drilled on the coated surface to expose the underlying steel, amounting to 4 per cent of the specimen surface area. These specimens were then exposed to boiling synthetic seawater for different periods: 2, 68, 188, 335 and 5,000 h. During exposure, the potential was monitored (vs standard calomel electrode [SCE]) and linear polarisation resistance (LPR) method was used to calculate the corrosion rate (CR). After exposure, these specimens were analysed by using characterisation tools such as X-ray diffraction (XRD) and scanning electron microscope (SEM)/energy-dispersive X-ray spectroscopy (EDX).FindingsThe TSA-coated steel samples with 4 per cent holiday showed a CR of approximately 0.008-0.015 mm y−1 and a stable potential (Ecorr) around −800 mV (SCE), when exposed to boiling synthetic seawater for approximately 5,000 h. Microstructural characterisation established that the deposits comprised brucite [Mg(OH)2] only (this is very different to what has been reported at ambient temperatures). The stable potentials obtained after 5,000 h suggest that the brucite layers provided effective corrosion mitigation. Thus, TSA seems to show the potential to protection hot carbon steel risers, even when damage exposing the external steel surface to the seawater is present.Originality/valueThe mechanism of calcareous deposit formation has been studied for many years, but most of the previously reported studies concentrate on low or ambient temperature behaviour. The reported studies mainly concentrate on the application of cathodic protection, rather than the effect of TSA. This is the first journal paper where the behaviour of damaged TSA in boiling synthetic seawater has been reported. The formation of brucite-only layer in the damaged area adjacent to the steel surface in boiling synthetic seawater is novel. And the mechanism of formation of this layer has been explained in the paper.

The Effect of Temperature and Local pH on Calcareous Deposit Formation in Damaged Thermal Spray Aluminum (TSA) Coatings and Its Implication on Corrosion Mitigation of Offshore Steel Structures

This paper is based on experimental data and provides better understanding of the mechanism of calcareous deposit formation on cathodically polarized steel surfaces exposed to synthetic seawater at 30 °C and 60 °C. The study comprises measurement of the interfacial pH of thermally sprayed aluminum (TSA) coated steel samples with and without a holiday (exposing 20% of the surface area). Tests were conducted at the corrosion potential for up to 350 h. It was experimentally determined that the local pH adjacent to the steel surface in the holiday region reached a maximum of 10.19 and 9.54 at 30 °C and 60 °C, respectively, before stabilizing at about 8.8 and 7.9 at the two temperatures. The interfacial pH on the TSA coating at 30 °C was initially 7.74 dropping to 4.76 in 220 h, while at 60 °C it increased from pH 6.41 to the range pH 7.0–8.5. The interfacial pH governed the deposition of brucite and aragonite from seawater on the steel surface cathodically polarized by the TSA. This mechanism is likely to affect the performance of TSA-coated offshore steel structures, especially when damaged in service.

Study on weld seam surface deposits of CuSi3 CMT brazing

CuSi3 CMT brazing is an advanced welding technology widely used in automotive industry. But dark deposits defect was found on the weld seam surface. SEM and EDS analyses were operated in this paper and this surface was found to contain three areas: area A with silicates thin film and Cu, area B with MnO·SiO2 silicates, and area C with CuO. And thus the formation mechanism of surface deposits, which was mainly attributed to the generation and uneven distribution of large amount of dark CuO, was proposed. Based on the mechanism of the deposit formation, four methods were processed to suppress the surface dark deposits. Ar + 2%O2 would prevent the generation of dark deposits because of enhanced cathode crushing effect. Besides, delay gas protection time, keep torch travel angle positive, and maintain a low heat input would be benefit for suppressing dark deposits on the weld seam surface.

Deposit formation mechanisms in a pulverized coal fired grate for hematite pellet production

Pulverized coal combustion was adopted at the end of the grate to provide sufficiently high preheating temperature in the grate when hematite was roasted to produce hematite pellets. Unfortunately, serious deposit which stuck to the walls at the end of the grate was found after using pulverized coal combustion. In the present study, chemical analysis methods were used to detect the chemical compositions of the preheated pellet powder, deposit sample and coal ash. In addition, the major phases and microstructure of the deposit sample were determined using X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive spectrometer (EDS) analysis, respectively. Furthermore, a thermodynamic software (FactSage 7.0) was adopted to analyze the deposit formation process. The chemical and mineralogical analyses indicated that the deposits contained high amounts of iron, particularly of silicate, aluminum, calcium and magnesium and, to lesser extent, of alkali metals. The deposit formation process in the grate was found to be caused by the mixing of hematite pellet fines and unburnt carbon from the coal ash. The hematite was reduced to wustite by the presence of residual carbon, which generated low melting phases forming sticky deposits on the grate walls.

Investigation of characteristics and formation mechanisms of deposits on different positions in full-scale boiler burning high alkali coal

Zhundong coalfield are huge in China; however, high alkali contents induce severe slagging and fouling problems in boiler. To obtain the characteristics and formation of deposits in boiler burning high alkali coal, the deposits at different positions were sampled in a 350MW boiler burning Zhundong coal, and analyzed by X-ray Fluorescence. The results indicated that the slagging was deteriorating from bottom to top at water wall. The slag with obvious layer structure only presented at platen superheater. The deposits in horizontal flue were mainly formed from the solidified particles attachment. To further understand the formation mechanism of layer structure in slag at platen superheater, the slag was separated according to the morphology and each layer was analyzed by X-ray Diffraction. The results suggested that through the condensed CaSO4 was the main compounds for the strong thermophoresis in layer 1, the little fused particles with high sodium content played the key bonding role. For layer 2, the fused particles contain high sodium content adhered to deposit surface and formed melt surface, which capture the other particles. The Fe species captured by melt surface lower the melting temperature of the formed deposit, and then aggravated the deposit fusibility in layer 3.

Effects of Coal Bottom Ash on Deposit in a Full-Scale Biomass-Fired Circulating Fluidized Bed Boiler

The efficiency of electricity production in biomass-fired circulating fluidized bed (CFB) boilers needs to be enhanced, which may increase the risks of high-temperature corrosion (HTC) as a side effect derived from the higher steam temperature. In this study, coal bottom ash (CBA) obtained from a pulverized coal-fired power plant was used to replace all the regular bed materials (quartz sand) in a biomass-fired CFB boiler, attempting to solve its HTC problem. Two kinds of mature deposits on the high-temperature superheater with regular bed materials and with CBA as a bed material were obtained and analyzed in detail. The deposit formation mechanisms with regular bed materials were discussed. Our results show that CBA can capture 22% of potassium during biomass combustion in the CFB boiler. However, CBA cannot effectively decrease the deposition of potassium chloride on high-temperature superheater, therefore leaving a serious HTC problem. The low effect of CBA for potassium capture may derive from its low...

Properties of ash generated during sewage sludge combustion: A multifaceted analysis

This paper presents chemical properties of sewage sludge ashes required for determining their thermal characteristics. A novel approach, linking selected advanced analytical techniques with FactSage modelling, was developed and applied to obtain new information on deposit formation mechanisms that contribute to fouling and slagging. The mineral matter and fusion temperatures were investigated using a variety of analytical techniques including XRF, ICP-MS, XRD, SEM-EDX and AFT. The slagging and fouling indices were calculated and the sintering properties were predicted. The studied ashes were rich in P2O5, CaO, SiO2 and Fe2O3, but their concentrations slightly differed. Phase analyses suggested the existence of calcium and phosphorus as main phases. Thermal behaviour of ashes was studied focusing on the mass loss, temperature peaks and thermic effects with the increasing of temperature up to 1200 °C under air atmosphere. The changes in concentration of ash compounds contributed to differences in ash fusion temperatures. FactSage thermochemical equilibrium calculations were used to predict the amount of liquid slag and solid phases, giving information about slagging properties of ashes. The general conclusion based on experimental studies is that sewage sludge ashes cause the slagging and fouling hazard while they reveal low corrosive effect.

2015 Homer W. Smith Award: The Podocyte from Periphery to Center Stage.

This overview summarizes selected major developments over the last 40 years in understanding podocyte biology and its involvement in glomerular disease subjectively from my perspective. Serendipity has played a major role in my contributions to investigative nephrology that range from basic mechanisms of immune deposit formation in experimental membranous nephropathy to the role of a microRNA in FSGS. This review emphasizes the importance of continuous reality checks of experimental results obtained in vitro or with genetically modified animals with human disease.

Deposition of coal ash on a vertical surface in a 100 kW downflow laboratory combustor: A comparison of theory and experiment

This paper is concerned with deposition rates of coal ash on a vertical surface in a 100kW rated down-flow laboratory coal combustor. At that scale, flow in the post flame where deposition occurs, is laminar, and the deposits on a vertical surface are similar to the early, sticky, inner deposits on horizontal surfaces. Therefore the problem addressed has relevance to understanding mechanisms of deposit formation in general. Experimental data presented here consist of particle size distributions of the ash aerosol, and time resolved measurements of the vertical deposit mass, for various controlled surface temperatures, one coal, and two combustion conditions: air-firing and oxy-firing with 50% inlet O2. Theory consisted of a transport model in which the criterion on whether an ash particle was captured, depended on a newly introduced “Thermophoresis Number”, Tp, which is the ratio of the time taken for the particle to contact the (cold) surface through thermophoresis, to that for the particle to pass by the surface. If Tp <1 the particle is captured; otherwise it escapes. It is assumed that only those particles in the sub-micron vaporization mode are both subject to thermophoresis and will stick to the surface. Using calculated velocity and temperature fields in the fluid next to the vertical surface, and the Tp <1 criterion alluded to above, it was possible to calculate a two-dimensional cross-sectional area that defined the area through which all particles that will contact the vertical surface must pass. Ash deposition rates so calculated were compared to experimental data. Quantitative agreement between theory and experiment was fair, considering the difficulties in accurately measuring deposition rates and in view of simplifications contained in the model.

Pathogenesis and treatments of TGFBI corneal dystrophies.

Transforming growth factor beta-induced (TGFBI) corneal dystrophies are a group of inherited progressive corneal diseases. Accumulation of transforming growth factor beta-induced protein (TGFBIp) is involved in the pathogenesis of TGFBI corneal dystrophies; however, the exact molecular mechanisms are not fully elucidated. In this review article, we summarize the current knowledge of TGFBI corneal dystrophies including clinical manifestations, epidemiology, most common and recently reported associated mutations for each disease, and treatment modalities. We review our current understanding of the molecular mechanisms of granular corneal dystrophy type 2 (GCD2) and studies of other TGFBI corneal dystrophies. In GCD2 corneal fibroblasts, alterations of morphological characteristics of corneal fibroblasts, increased susceptibility to intracellular oxidative stress, dysfunctional and fragmented mitochondria, defective autophagy, and alterations of cell cycle were observed. Other studies of mutated TGFBIp show changes in conformational structure, stability and proteolytic properties in lattice and granular corneal dystrophies. Future research should be directed toward elucidation of the biochemical mechanism of deposit formation, the relationship between the mutated TGFBIp and the other materials in the extracellular matrix, and the development of gene therapy and pharmaceutical agents.

Fouling Deposits from Residual Biomass with High Sodium Content in Power Plants

Unusually large fouling deposits on the heat transfer tubes of a power plant using a residual product from olive extraction, which led to boiler shutdowns, have been attributed to an unusually high sodium content in the feed biomass. To confirm this and to evaluate the mechanisms of deposit formation, different techniques were used to analyze feed biomass and mature deposits sampled at different locations of the convection section: inductively coupled plasma, fusion test, energy dispersive X-ray fluorescence spectrometry, and scanning electron microscopy. All the deposits sampled were divided into two layers: a thin inner layer mainly composed of potassium and chlorine and a more porous outer layer with higher content in less volatile elements such as Ca, Si, Al, and Fe, both layers showing high sodium content. Differences in composition and morphology were also found depending on the temperature of the region where the deposits were formed and on the sampling position, frontside or backside, with respect to gas stream. Frontside deposits showed higher porosities and were mainly composed of granular and spherical structures, whereas backside ones showed higher compaction and are mainly composed of crystalline structures formed on the deposit surface. Structures were categorized based on their shape, and some relationships between shape and composition were proposed, which supported hypotheses about their formation mechanisms. Structures defined as amorphous molten were sticky, therefore increasing the capturing efficiency and tenacity of the deposit and leading to large deposits difficult to remove. The high sodium content of these structures was associated with the high sodium content of the feed biomass. Limiting this element is recommended to prevent uncontrolled deposit formation in the boiler.

Method of Evaluation of Deposit Forming Tendency of Automotive Gasolines in Injection Systems in Osv-01 Motorless Unit

The characteristics and mechanism of deposit formation in spray injection system of gasoline engines are discussed. A motorless unit and a method of evaluation of deposit forming tendency of automotive gasolines in spray injection systems are developed. The criterion of numerical evaluation of pollutants based on degree of darkening of spray injector bottom is proposed. The results of tests, by the proposed method, of individual hydrocarbons and their mixtures as well as of several gasolines of different producers are adduced. Among the individual hydrocarbons, unsaturated hydrocarbons and nitrogen-bearing compounds contribute the most to deposit formation, and additivity and synergy effect are not typical for the deposit formation process. Among the commercial gasolines, those containing MMA (monomethyl aniline) or a substantial quantity of catalytically cracked fractions and not containing detergent additives exhibit maximum deposit forming tendency. Minimal deposit formation is typical for gasolines containing detergent additives.

Petrological, geochemical, and mineralogical compositions of the low-Ge coals from the Shengli Coalfield, China: A comparative study with Ge-rich coals and a formation model for coal-hosted Ge ore deposit

To better understand the formation mechanism of coal-hosted Ge ore deposits, this paper reports on the petrological, mineralogical, and geochemical compositions of the low-Ge coals in the Shengli Coalfield (Inner Mongolia, China), using optical microscopy, field emission-scanning electron microscopy, X-ray fluorescence, X-ray diffraction, and inductively coupled plasma mass spectrometry. The samples in the present study closely neighbor the previously-reported Wulantuga coal-hosted Ge ore deposit (both No. 6 Coal). In comparison with the Wulantuga Ge-rich coals, the low-Ge coals of the Shengli field display higher moisture (27.59% on average) and lower pyritic sulfur contents (0.53%). Both the low-Ge and Ge-rich coals are generally high in inertinite, and have varying but relatively low huminite contents. Preservation of fecal pellets as macrinite is notable in both the low-Ge and Ge-rich coals, and the position of the fecal pellets appears to be within tunnels or chambers within the wood. Quartz, kaolinite, pyrite, and gypsum are the major crystalline phases identified in most of the Ge-rich and low-Ge coals, but the low-Ge coals contain significantly less pyrite and are more abundant in non-mineral Ca and Mg. Ca-oxalate of authigenic origin is observed, generally occurring as cell-fillings in the low-Ge coals. Otherwise mineral-free organic matter in the low-Ge coals would be expected to have an inherent ash yield of around 6%, derived from the inorganic elements (mainly non-mineral Ca and Mg) that occur either in the organic matter or as dissolved ions in the pore water and form the sulfate species in low-temperature (oxygen-plasma) ash residues. The highly-elevated trace elements, including Be, Ge, As, Sb, W, Hg, and Tl, that occur in the Ge-rich coals of the Wulantuga deposit, are significantly depleted in the low-Ge coals. Lateral migration of Ge–W- and As–Hg–Sb–Tl-rich solutions through the original peat swamp for the Wulantuga Ge ore deposit has led to significant enrichment of Ge on the margin of the coal basin but decreasing Ge concentrations toward to the inner part of the basin. Such a migration direction is different to those in the previously-reported for the hydrothermal solutions in the Lincang (Yunnan of China) and Spetzugli (Russian Far East) Ge ore deposits, where the solutions migrated vertically from granite to peat along faults and led to a dome-shaped Ge distribution in the relevant coal seam.

Assumed Mechanism of Polymeric Deposit Formation in Recycle Propylene Washing Column during Bulk Polymerization

This study presents the results of polymeric deposit analysis from propylene washing column of «Spheripol» process polymerization unit using such methods as gel-permation chromatography, differential scanning calorimetry (DSC), X-ray phase analysis, IR and NMR13C-spectroscopy and analytical process control methods. For comparison the relative data for larger volume polypropylene grades have been presented as well. Based on the findings and available similar practice in a slurry process an assumed formation mechanism was proposed for the discussion.