Forces generating crystallization differentiation, and the evolution of the melt composition on the example of plagioclase

2020 ◽  
Vol 26 (7) ◽  
pp. 44-52
Author(s):  
А. Kirdyashkin ◽  
◽  
A. Kirdyashkin ◽  
Keyword(s):  
Hydrodynamic Instability ◽  
Continuous Solid Solution ◽  
Thermal Power ◽  
Liquidus Line ◽  
Solid Particles ◽  
Oxide Content ◽  
Particle Settling ◽  
Weight Percentage ◽  
Crystallization Differentiation ◽  
Melt Composition

Crystallization differentiation processes in the melt volume are investigated for albite-anorthite continuous solid solution series. It has shown that crystallization differentiation occurs in the isothermal melt volume due to hydrodynamic instability of the melt/solid particles system. The time of particle settling in a 10 cm thick melt layer is estimated for different particle sizes. In terrestrial conditions, the existence of large melt volumes with long lifetime is possible in the case of a long-lived heat source of high thermal power. This source is a mantle thermochemical plume with a mushroom-shaped head. The particle settling time is estimated for the melt layer thickness, i. e. plume head thickness equal to 10 km. A calculation technique is presented for composition of the melt remaining after settling of plagioclase particles. The results of calculations of changes in the melt composition due to crystallization differentiation at a temperature T = 1410 °C and a pressure P = 6,3 kbar are presented. For a melt whose composition corresponds to N 47,5 (weight percentage of anorthite is 47,5 %), the oxide content in the settled plagioclase, the composition of the melt in its intercrystalline spaces, and the residual melt composition are calculated. At constant temperature, the crystallization differentiation of the melt whose composition corresponds to plagioclase leads to the compositional changes in the initial melt. Calculations of the melt composition have shown that the melt is depleted in anorthite component owing to settling of plagioclase particles. The composition of plagioclase therewith shifts to the liquidus line, reaching its limit on this line

. Influence of crystallization differentiation on the composition of the residual melt for plagioclase under different p-t conditions

2020 ◽  
Vol 26 (7) ◽  
pp. 53-61
Author(s):  
A. Kirdyashkin ◽  
◽  
A. Kirdyashkin ◽  
Keyword(s):  
Similarity Theory ◽  
Liquidus Line ◽  
Solid Particles ◽  
Similarity Criteria ◽  
Analytical Relationship ◽  
Oxide Content ◽  
Calculation Technique ◽  
Crystallization Differentiation ◽  
Melt Composition ◽  
Residual Melt

Crystallization differentiation processes in the melt volume for albite-anorthite solid solution series have been studied. For the albite-anorthite system, the change in the melt composition due to crystallization differentiation is calculated for pressure values P = 6,3 kbar and 1 bar and temperature T = 1410 °C, 1350 and 1300 °C. A calculation technique is presented for composition of the melt remaining after settling of plagioclase particles. The residual melt compositions have been calculated for different initial melt compositions and different P-T parameters. The change in composition due to crystallization differentiation of the melt is the difference in the percentage composition for each oxide on the liquidus line and the initial melt composition. The dimensionless ratios (similarity criteria) for the initial melt composition and the change of the oxide content , , , have been obtained. The change of each oxide percentage is calculated in weight percents and in the dimensionless form (as values of above-mentioned similarity criteria). The initial melt is depleted in different components. The depletion is due to settling of plagioclase particles and melt volume reduction. The latter is the sum of the solid particles and the melt volumes in the intercrystalline spaces of the settled particles’ layer. It is shown that the processes of crystallization differentiation are the sum total of hydrodynamic (geodynamic) and petrological processes. These processes can be studied using the methods of similarity theory. The compositional change in the melt due to crystallization differentiation can be represented in the form of an analytical relationship between the petrological similarity criteria

scholarly journals FEATURES OF MELTING IN THE THERMOCHEMICAL PLUME CONDUIT AND HEAT AND MASS TRANSFER DURING CRYSTALLIZATION DIFFERENTIATION OF BASALTIC MELT IN A MUSHROOM-SHAPED PLUME HEAD

2019 ◽  
Vol 10 (1) ◽  
pp. 1-19 ◽  
Author(s):  
A. A. Kirdyashkin ◽  
A. G. Kirdyashkin ◽  
N. V. Surkov
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Thermal Power ◽  
Eutectic Type ◽  
Oxide Content ◽  
Melt Temperature ◽  
Crystallization Differentiation ◽  
Basaltic Melt ◽  
Thermochemical Plume ◽  
Residual Melt

The number Ka=N/N1is used to evaluate the thermal power of a plume;Nis the thermal power transferred from the plume base to its conduit, andN1is the thermal power transferred from the plume conduit into the surrounding mantle. At the relative thermal power 1.9<Ka<10, after eruption of the melt from the plume conduit to the surface, melting occurs in the crustal block above the plume roof, resulting in the formation of a mushroom-shaped head of the plume. A thermochemical plume originates at the core-mantle boundary and ascends (melts up) to the surface. Based on laboratory and theoretical modeling data, we present the flow structure of melt in the conduit and the head of the thermochemical plume. The features of melting in the plume conduit are elucidated on the basis of the phase diagram of the CaO-MgO-Al2O3-SiO2model system. The two upper convection cells of the plume conduit relate to the region of basic and ultrabasic compositions. Our study shows that melting in these cells proceeds according to monovariant equilibria of eutectic type L=Cpx+Opx+An+Sp and L=Fo+An+Cpx+Opx. In case of the CaO–MgO–Al2O3–SiO2–Na2O system, crystallization differentiation proceeds as separation of plagioclase crystals. Separation of plagioclase crystals enriched in anorthite component leads to enrichment of the residual melt in silica and alkaline components. Assuming the initial basaltic melt, we calculated the compositional changes in the melt, which are powered by the heat and mass transfer processes in the mushroom-shaped plume head. The calculations were performed in two stages: (1) after settling of refractory minerals; (2) after settling of plagioclase in the melt resulting from the first stage. In the second stage, the melt contains 88.5 % of plagioclase component. The calculations were performed for melt temperatureTmelt=1410 °C and pressureP=2.6 kbar and 6.3 kbar. The calculated weight contents of oxides, the normative compositions for solid phase, and the oxide content and normative composition for the residual melt were tabulated. The SiO2content in the residual melt amounts to 59.6–62.3 % and corresponds to the crustal SiO2content.

Effect of Cenosphere Addition on Mechanical Properties of Bamboo and E-Glass Fiber Reinforced Epoxy Hybrid Composites

2020 ◽  
Vol 12 (4) ◽  
Author(s):  
B.K. Venkatesh ◽  
R. Saravanan
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Glass Fiber ◽  
Hybrid Composite ◽  
Power Plants ◽  
Hybrid Composites ◽  
Thermal Power ◽  
Element Analysis ◽  
Weight Percentage ◽  
Experimental Values

Cenosphere is a ceramic-rich industrial waste produced during burning of coal in the thermal power plants. This study deals with the effect of cenosphere as particulate filler on mechanical behaviour of woven bamboo-glass hybrid composites. The hybrid composite consists of bamboo and E-glass fiber as reinforcement and epoxy as matrix. Cenosphere of different weight percentage (0.5, 1, 1.5 and 2 %) was added to the hybrid composite. The samples were tested as per ASTM standards for their mechanical properties to establish the effect of filler content. It is found that the mechanical properties are significantly influenced by addition of waste ceramic filler cenosphere up to 2 wt.% and increases the tensile, flexural and inter-laminar shear strength in comparison to unfilled composite. Finite element analysis is also done using Midas NFX and the simulation results are compared with experimental results. From the results, it has been found that the experimental values obtained from tensile testing and flexure testing nearly matches with finite element values.

The Effect of Titanium Oxide Content in Piston Coating on the Performance and Emission Characteristics of Bio-Diesel Fuelled C.I. Engine

2013 ◽  
Vol 795 ◽  
pp. 24-28 ◽  
Author(s):  
C.R. Rajashekhar ◽  
C. Umashankar ◽  
T.K. Chandrashekar ◽  
P. Naveen
Keyword(s):  
Titanium Oxide ◽  
Cooling System ◽  
Thermal Barrier ◽  
Emission Characteristics ◽  
Oxide Content ◽  
Weight Percentage ◽  
Performance And Emission ◽  
Piston Crown ◽  
Barrier Coating ◽  
Hc Emissions

Thermal barrier coating has proven to be effective in improving the thermal efficiency and initiation of an effective cooling system of the engine. In the present work the engine piston crown was plasma coated with 150μm thicknss of catalytic ceramic material Alumina-Titanium oxide (Al2O3-TiO2) over a 60μm thickness of NiCrAl bond coat. Available literature on this topic suggest that the particular effect of TiO2 on the over all thermal barrier characteristics have not been established clearly. It was therefore felt that the effect of weight percentage of TiO2 in the Al2O3-TiO2, might influence the performance and emission characteristics of the engine. The TiO2 weight % has been tested at 10% and 15% levels. The engine used was four strokes, single cylinder direct injected diesel engine. The engine was tested with diesel & at 30% Honge bio-diesel with diesel and the results obtained clearly indicate that the specific fuel consumption, CO & HC emissions have come down by increasing the weight % of TiO2.

scholarly journals Providing of technological norm on oxides of sulphur for steam boilersat thermal power stations

2021 ◽  
Vol 22 (6) ◽  
pp. 164-175
Author(s):  
A. M. Gribkov
Keyword(s):  
Power Plants ◽  
Thermal Power ◽  
Combustion Products ◽  
Absorption Capacity ◽  
Solid Particles ◽  
Fuel Oil ◽  
Oil Refining ◽  
Thermal Power Plants ◽  
Power Stations ◽  
Slaked Lime

Thermal power plants (TPPs) burn more than 30% of the produced fuel. Also this fuel is worst in quality. This is usually either high-ash or high-moisture, often high-sulfur coal, or waste from oil refining and associated petroleum gas. If the main fuel at the plant is natural gas, then fuel oil farms are still being built to create a fuel reserve. But even if a gas-oil plant uses only a small part of fuel oil in its fuel balance, the permissible environmental impact is calculated on the maximum use of the dirtiest fuel, i.e. fuel oil. Thus, thermal power plants are either active or potential sources of nitrogen oxide emissions. PURPOSE. Development of methods for decreasing sulfur emissions without installing special desulphurization equipment in the exhaust gas path. In some cases, this is possible if the absorption capacity of the alkaline components of solid fuel ash or the dosing of slaked lime into fuel oil is used to control the permissible emission of solid particles in the absence of ash collectors on gas-and-oil boilers. The developed METHODOLOGY will allow us to trace the entire chain of necessary actions based on the fuel composition before selecting the main parameters of the proposed methods. RESULTS. The formulas for calculating the required degree of purification of combustion products are proposed. Methods decrease sulfur oxides emissions in domestic equipment using for pulverized coal boilers. Solution allows to decrease oxide emissions for boilers that burn fuel oil and do not have ash traps.

scholarly journals Application of PAC and flocculants for improving settling of solid particles in oilfield wastewater with high salinity and Ca2+

2017 ◽  
Vol 76 (6) ◽  
pp. 1399-1408 ◽  
Author(s):  
Guoliang Liu ◽  
Fusheng Zhang ◽  
Yuanzhi Qu ◽  
He Liu ◽  
Lun Zhao ◽  
...  
Keyword(s):  
Particle Size ◽  
Calcium Ion ◽  
Suspended Solids ◽  
High Salinity ◽  
Particle Size Analysis ◽  
Solid Particles ◽  
Size Analysis ◽  
High Concentration ◽  
Particle Settling ◽  
High Calcium

The suspended solids in wastewater from Rekabak oilfield, Kazakhstan, were characterized and treated with flocculants to enhance settling. The wastewater contained a high concentration of total dissolved solids and calcium ion. Scanning electron microscopy and energy dispersive X-ray analyses showed that suspended solids were mainly composed of corrosion products (iron oxides) and silicon dioxide particles. Also, much salt deposition from wastewater caused a large increase in the suspended solids value. The settling of solid particles in wastewater was investigated by turbidity decrease within 60 min. The particle settling was enhanced by adding polyaluminum chloride (PAC) as coagulant and hydrolyzed polyacryamide (HPAM) or cationic polyacrylamide (CPAM) as flocculant. At optimal dose, the particle settling ability with PAC and CPAM was better than that with PAC and HPAM. Particle size analysis showed that HPAM or CPAM with high molecular weight played an important role for enlarging the particle size. The experiments with simulated wastewater showed that particle settling by using HPAM deteriorated significantly compared to that by CPAM at high calcium ion. This study provides further understanding about the effect of high salinity and Ca2+ on solids formation, flocculant performance and particle settling. Meanwhile, the results are also helpful to develop novel flocculants used for high salinity wastewater.

scholarly journals Application of various approaches to modeling the gas emissions from TPP cleaning processes

2021 ◽  
Vol 315 ◽  
pp. 01003
Author(s):  
Olesya Aksenova ◽  
Evgenia Nikolaeva
Keyword(s):  
Power Plants ◽  
3D Visualization ◽  
Thermal Power ◽  
Appropriate Technology ◽  
Solid Particles ◽  
Design Stage ◽  
Modeling Tools ◽  
Gas Emissions ◽  
Mathematical Processing ◽  
A Site

The article discusses the possibility of 3D computer modeling tools complex use based on the mathematical processing of the gas emissions from TPP cleaning process. The authors propose to consider an approach to designing a site for capturing solid particles in gas emissions that appear during the production activities of an industrial enterprise by modeling a technological site in various programs. Mathematical processing with the use of the E-network device and the creation of a 3D model enables to plan a site for capturing solid particles in gas emissions, choose the appropriate technology and thereby ensure the ecological effect of both existing and projected power plants. The authors present the results of processing the technological process of gas purification at thermal power plants in terms of E-networks using mathematical processing in the Simulink application, which displays a device model from the standard units available in the program and performs the necessary calculations. 3D models of individual pieces of equipment selected on the basis of mathematical processing calculations in the Simulink application were created using computer 3D modeling in a graphical editor. A 3D visualization of the technological site for capturing solid particles in gas emissions was carried out, enabling a visual display of the planned site at the design stage, which, if necessary, will allow an easy introduction of modifications to the project.

Development of Novel Natural Composites with Fly Ash Reinforcements and Investigation of their Tensile Properties

2016 ◽  
Vol 852 ◽  
pp. 55-60 ◽  
Author(s):  
A. Praveen Kumar ◽  
M. Nalla Mohamed ◽  
K. Kurien Philips ◽  
J. Ashwin
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Tensile Properties ◽  
Power Plants ◽  
Thermal Power ◽  
Waste Product ◽  
Natural Fibers ◽  
Natural Fibre ◽  
Weight Percentage ◽  
Natural Composites

Increasing demand for special materials leads to new inventions. One of the most promising inventions is the concept of composites. Natural fibers have the potential as a reinforcing material as an alternative to the use of glass, carbon and other synthetic fibers in automotive industries. Among various natural fibers, Kenaf is a widely used fiber due to its easy availability, low density, low production cost and satisfactory mechanical properties. To enhance the mechanical properties of natural fibre composites, strengthening of the matrix and fibre is very much essential. A prospective reinforcement in this regard is fly ash, which is abundantly available as a waste product from thermal power plants. In this paper, a new novel natural composite with epoxy as a resin and reinforcing both bio waste (Kenaf) and industrial waste (Fly ash) has been developed. All the laminates were prepared with a total of 4 plies. Laminates without fly ash filler were also fabricated for comparison purpose. A hand lay-up method was used for the fabrication of composites and was tested as per ASTM standards for evaluation of tensile properties. The effect of fly ash weight percentage (5, 10, 15% wt.) on tensile properties was studied experimentally. Due to the incorporation of fly ash fillers into the kenaf fiber composites, there is considerable improvement in the mechanical properties. Overall results supported the effective utilization of natural composites for automotive applications.

scholarly journals Erosion Wear of Axial Flow Impellersin a Solid-liquid Suspension

10.14311/182 ◽  
2001 ◽  
Vol 41 (1) ◽  
Author(s):  
I. Fořt ◽  
J. Medek ◽  
F. Ambros
Keyword(s):  
Pitch Angle ◽  
Brinell Hardness ◽  
Thermal Power ◽  
Axial Flow ◽  
Leading Edge ◽  
Solid Particles ◽  
Erosion Wear ◽  
Erosion Process ◽  
Impeller Blade ◽  
Sheet Erosion

A study was made of the erosion wear of the blades of pitched blade impellers in a suspension of waste gypsum from a thermal power station (vol. concentration CV=18.3 %, particle mean diameter d=0.1 mm, degree of hardness “2.5”) and silicious sand (CV=10 %, d=0.4 mm, degree of hardness “7.5”) in water under a turbulent flow regime of agitated charge when complete homogeneity of the suspension was achieved. Experiments were carried out on pilot plant mixing equipment made of stainless steel (diameter of cylindrical vessel T=390 mm, diameter of impeller D=100 mm, impeller off-bottom clearance h=100 mm) equipped with four wall radial baffles (width b=39 mm) and an impeller with four inclined plane blades (pitch angle α =20°, 30°, 45°, relative blade width W/D=0.2) made either of rolled brass (Brinell hardness 40–50 BH) or of structural steel (Brinell hardness 100–120 BH) always pumping the liquid downwards towards the flat vessel bottom. Two erosion process mechanisms appear, depending on the hardness of the solid particles in the suspension: while the particles of gypsum (lower hardness) generate a uniform sheet erosion over the whole surface of the impeller blade, the particles of silicious sand (higher hardness) generate wear of the leading edge of the impeller blades, together with a reduction of the surface of the worn blade. The hardness of the impeller blade also affects the rate of the erosion process: the higher the hardness of the impeller blade, the lower the wear rate of the blade. This study consists of a description of the kinetics of the erosion process of both mechanisms in dependence on the pitch angle of the tested impellers. While the wear of the leading edge of the blade exhibits a monotonous dependence on the pitch angle, the sheet erosion exhibits the maximum rate within the interval of the pitch angles tested α ϵ <20°; 45°>.However, generally the pitch angle α =45° seems to be the most convenient angle of blade inclination when both investigated mechanisms of the blade erosion process are considered at their minimum rate.

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