微粉化超净煤燃液生产工艺的研究

介绍了一种微粉化超净煤燃液的生产方法:简述了其主要生产设备及参数,介绍了研磨工序、压滤工序、超净煤燃液高强剪切工序的生产过程,分析了不同研磨时间、剪切时间和剪切速率对微粉化超净煤燃液粒度和黏度的影响。结果表明,采用该工艺生产的微粉化超净煤燃液具有特定的粒度分布及良好的流变特性,可应用于直喷式燃油发动机。

Microwave digestion and alkali fusion assisted hydrothermal synthesis of zeolite from coal fly ash for enhanced adsorption of Cd(Ⅱ) in aqueous solution

A novel microwave digestion and alkali fusion assisted hydrothermal method was proposed to synthesize zeolite from coal fly ash and the zeolite product was studied for removal of Cd(II)from aqueous solution through batch experiments.The adsorbent was characterized by X-ray diffraction,scanning electron microscopy,Fourier transform infrared spectroscopy,surface area analyzer and zeta potential measurement.The results show that the synthetic zeolite was identified as faujasite.The optimum conditions for removal of Cd(II)are found to be:adsorbent dose of0.5g/L,pH6,contact time of90min and initial concentration of20mg/L,the removal rate of Cd(II)is98.55%.The experimental kinetic data agree well with the pseudo second-order equation;the Langmuir isotherm model is found to be more suitable to explicate the experimental equilibrium isotherm results than Freundlich,Dubinin-Radushkevich and Temkin models,and the maximum adsorption capacity of Cd(II)is found to be86.96mg/g.The thermodynamic parameters such asΔGΘ,ΔHΘandΔSΘwere evaluated and the results show that the adsorption of Cd(II)onto the as-synthesized zeolite is spontaneous,endothermic and feasible under studied conditions.

Determination of trace multi-elements in coal fly ash by inductively coupled plasma mass spectrometry

The contents of Cr, Cu, Ni, As, Cd and Pb in coal fly ash were determined by a high resolution inductively coupled plasma mass spectrometry method. The sample digestions were performed in closed microwave vessels with HNO3, HClO4 and FIE The optimum conditions for the determination were obtained. The applicability of the proposed method was validated by the analysis of coal fly ash reference material （NIST SRM 1633a）. The results show that most of the spectral interferences can be avoided by measuring in the high resolution mode （maximum mass resolution R=9 000）. The detection limit is from 0.05 to 0.21 μg/g, and the precision is fine with relative standard deviation less than 4.3%.

Effect of sodium sulfate on strength and microstructure of alkali-activated fly ash based geopolymer

The main objective of this paper focuses on the changes that occur in the strength and microstructural properties of sodium silicate activated fly ash based geopolymer due to varying the sulfate salt and water content.A series of tests including X-ray diffraction,Fourier transform infrared spectroscopy,scanning electron microscopy,physical adsorption and unconfined compressive strength were used to investigate this effect.The results indicate that the higher water content has an adverse effect on the alkali activation and microstructural properties of geopolymer,so the optimum mass ratio of sodium sulfate in alkali-activated geopolymer under different water-to-binder ratios shows a“peak shifting”phenomenon,i.e.,the higher the water-to-binder ratio,the higher the optimum mass ratio.Lower presence of sodium sulfate has no significant effect on the alkali-activated geopolymer systems;higher addition of sodium sulfate,however,could cause the symmetrical stretching vibration of Si—O and the symmetrical stretching vibration of Si—O—Si and Al—O—Si,and promote the formation of N-A-S-H gels.Furthermore,the cement effect of the gel and sodium sulfate aggregate could improve the integrity of pore structure obviously.The maximum strength of geopolymer curing at ambient temperature was 52 MPa.This study obtains the rule that the strength properties of alkali-activated geopolymers vary with the water-to-binder ratio and sodium sulfate content.The feasibility of geopolymer co-activated by sodium sulfate and sodium silicate was investigated,and reference for engineering application of alkali-activated geopolymer in salt-bearing areas was provided.

Factors Influencing Conversion of Pyritic Sulfur in Coal by Microwave Irradiation

The high sulfur coal from southwest of China was used to examine the influence of different factors such as irradiation time, particle size of coal, and leachant (Na2CO3, NaOH and CuCl22H2O)on the conversion rate of pyrite to pyrrhotite by microwave irradiation. Single factor experiment was performed firstly, then orthogonal test method was used to explore these factors. The result shows that the optimal treating conditions for the conversion are a treatment time of 3 min, a particle size from 0.086 mm to 0.102 mm, and a favorable leachant of sodium hydroxide. Under these conditions the conversion rate of pyrite can reach 45.7 %.

A novel method for measuring the moisture content of coal powder by microwave resonator

A novel technique for the quick measurement moisture content of coal powder by microwave was studied. The effects of the various moisture contents on the measurement results were also discussed. The experimental results show that the standard deviation is less than 0.36% when the moisture content of coal powder is 0.74%-16.90% and the standard deviation is less than 0.16% when the moisture content is 0.31%-1.49%. The experimental results indicate that a process of quick measurement moisture content of coal powder by microwave is practical.

Improved Sorting Scheme of Microstructure of Fly Ash

Aiming at the problem of the existing sorting for microstructure of fly ash, an improved scheme was put forward in this paper. First, fly ash particles are divided into four groups as low calcium, iron, high calcium and char particle according to the substance components of fly ash. Then fly ash particles are divided into 14 sub groups, for example: cenospheres, plerospheres, solid spheres, porous char and dense char based on their chemical composition, shape and the characteristics of inner structure of fly ash. It has a distinct difference in granule configuration, inner structure and substance components. Some disadvantages of the existing scheme such as unilateralism and imprecision have been overcome in the advanced schemes.

Nickel composite plating with fly ash as inert particle

The Ni/FA composite plating was realized by electrodeposition with fly ash （FA） as inert particles. The main compositions of FA are 72% SiO2 and 25% A1203 in the size of 3-7 Ixm. Electrodeposition was performed in Watts bath containing FA with concentrations of 5, 20, 50 g/L, current densities of 2 and 4 A/dm2, temperature of 50 ~C and magnetic stirring of 250 r/min. Scanning electron microscope （SEM＋EDX）, electrochemical and mechanical technique were used to study morphology, composition and properties of coating. FA content in deposit is dependent on the FA concentration in solution, as well as the plating parameters. Since FA particles were incorporated in the coating, the mechanical and electrochemical properties of the coating were increased. The microhardness of Ni/FA composite plating reaches HV 430 in comparison with HV 198 of pure Ni coating. It was confirmed by electrochemical measurement that the corrosion resistance of Ni/FA composite coating was higher than that of pure Ni.

Investigation on high-volume fly ash pastes modified with micro-size metakaolin subjected to high temperatures

Portland cement(PC) containing high-volume fly ash(HVFA) is usually used to obtain economical and more sustainable merits, but these merits suffer from dramatically low compressive strength especially at early ages. In this work, the possibility of using micro-size metakaolin(MSK) particles to improve the compressive strength of HVFA paste before and after subjecting to high temperatures was studied. To produce HVFA paste, cement was partially substituted with 70% fly ash(FA), by weight. After that, FA was partially substituted with MSK at ratios fluctuating from 5% to 20% with an interval of 5%, by weight. The effect of MSK on the workability of HVFA mixture was measured. After curing, specimens were subjected to different high temperatures fluctuating from 400 to 1000 ℃ with an interval of 200 ℃ for 2 h. The results were analyzed by different techniques named X-ray diffraction(XRD), thermogravimetry(TGA) and scanning electron microscopy(SEM). The results showed that the incorporation of MSK particles into HVFA mixture exhibited a negative effect on the workability and a positive effect on the compressive strength before and after firing.

Glass-ceramics made from arc-melting slag of waste incineration fly ash

Grate fly ash and fluidized bed fly ash mixed with glass cullet additive respectively were melted in the electronic arc-furnace. The product, arc-melting slag, was further treated by crushing, pressing and heat treatment in order to make the glass-ceramics. The crystallization behaviors of the produced glass-ceramics were examined by differential thermal analysis （DTA）, X-ray diffractometry （XRD） and scanning electron microscopy （SEM）. Results show that main crystalline phase of the glass-ceramics fi＇om grate fly ash is wollastonite （CaSiO3） with small amount of diopside （Ca（Mg,Al）（Si,Al）206）, and that from fluidized bed fly ash is diopside （Ca（Mg,Al）（Si,Al）206）. It is found that the glass-ceramics sintered at 850 ℃and 1 000℃ from grate fly ash and fluidized bed fly ash respectively have the optimal physical, mechanical and chemical characteristics. Glass-ceramics samples, produced from incinerator fly ash with desirable properties and the low leaching concentration of heavy metals, can be the substitute of nature materials such as marble, granite and porcelain tiles.

Microstructures and compressive properties of AZ91D/fly-ash cenospheres composites

Novel AZ91D Mg alloy/fly-ash cenospheres(AZ91D/FACs)composites were fabricated by melt stir technique.Fly-ash cenosphere particles with 4%,6%,8%,10%in mass fraction and 100μm in size were used.Hardness and compressive strength of the composites were measured.The effects of mass fraction of cenospheres on the microstructure and compressive properties were characterized.The results show that the cenospheres are uniformly distributed in the matrix and there is no sign of cenosphere cluster or residual pore.The densities of the composites are 1.85-1.92 g/cm 3 .By comparing with matrix,the compressive yield strength of the composites is improved,and the cenospheres is filled with Mg matrix alloy.SEM,XRD and EDX results of the composites show clear evidence of reaction product at cenosphere/matrix interface.On the basis of XRD and EDX,composition, structure and thermodynamic analysis,the main interfacial phase between the cenosphere and AZ91D Mg alloy was identified to be MgAl2O4.

Separating Performance of Fly Ash in Water Media

The stress state and floating sinking reqularity of various particles in fly ash in water were analyzed. The formula for calculating the floating sinking rate was given. And the formula for calculating the magnetic force needed to separate magnetic beads from magnetic separator was also obtained.

Effect of sintering temperature on microstructure and properties of glass-ceramics synthesized from waste cathode ray tubes funnel glass

Waste cathode ray tube(CRT)funnel glass(FG)is an important part in the disposal of electrical and electronic waste(e-waste).A novel approach for efficient lead extraction and glass-ceramics synthesized from waste FG through collaboratively smelting FG with coal fly ash(CFA)is proposed.Glass-ceramics materials with 40 wt%-80 wt%FG additions were produced under sintering temperatures of 900-1000℃.The microstructure and phase composition of the produced glass-ceramics were studied using X-ray diffraction(XRD)and scanning electron microscopy(SEM).The density,water absorption,Vicker hardness,chemical resistance and heavy metal leaching characteristics of the glassceramics were measured.The experimental results indicate that the samples can be crystallized at sintering temperatures of 900-1000℃.An elevated sintering temperature is favorable for enhancing the degree of crystallization,while the crystallization process is inhibited at excessively high temperatures.Increasing FG addition can lead to the transformation of the main crystalline phase from diopside to gehlenite.Well-crystallized crystals were generated in the specimens with 50 wt%-70 wt%FG additions.The samples with 40 wt%,50 wt%,60 wt%,70 wt%,80 wt%FG addition exhibit the optimal chemical and physical properties at 975,925,950,925 and 900℃,respectively.Overall results demonstrate that this study provides a feasible strategy for reliably detoxifying and reusing waste FG and CFA.

Microstructures and thermal properties of municipal solid waste incineration fly ash

To analyze the feasibility of utilization of thermal technology in fly ash treatment, thermal properties and microstructures of municipal solid waste incineration （MSW1） fly ash were studied by measuring the chemical element composition, specific surface area, pore sizes, functional groups, TEM image, mineralogy and DSC-TG curves of raw and sintered fly ash specimens. The results show that MSWI fly ash particles mostly have irregular shapes and non-typical pore structure, and the supersonic treatment improves the pore structure; MSWI fly ash consists of Such crystals as SiO2, CaSO4 and silica-aluminates, and some soluble salts like KCl and NaCl. During the sintering process, mineralogy changes largely and novel solid solutions are produced gradually with the rise of temperature. Therefore, the utilization of a proper thermal technology not only destructs those persistent organic toxicants but also stabilizes hazardous heavy metals in MSWI fly ash.

Study on Preparation of Ceramic Material and Its Properties

This paper introduces the classification, properties and application of porous ceramic materials, reviewed preparation of porous ceramics. Taking fly ash and red mud as the main raw material to generate porous ceramics, the paper study the influence of different proportions of raw materials, sintering temperature, porosity of porous ceramic sample rate, bending strength, and microstructure. The results show that, fly ash and red mud proportioning and sintering temperature are the main factors that influence the structure and properties of samples. The4#sample is a kind of high porosity and high strength quality of porous ceramics.

Getting and X-ray Diffraction Analysis of the Microsphere Catalyst U, Nd on the Basis Fly Ash of Thermal Power Plants

To study the physical and chemical properties of aluminosilicate microsphere catalyst by impregnation and calcination us was first obtained aluminosilicate microsphere catalyst U, Nd for petrochemical processes. The method of X-ray structure has been studied for the microsphere catalyst U, Nd.

Numerical Study on Reduction of NO_x and Unburned Carbon in Micronized Coal Reburning

Three dimensional numerical simulation of bituminous coal reburning in a full-scale tangentially fired boiler was conducted with CFD method to study the effects of reburn zone length, the height of reburn nozzles, the stoichiometric ratio in reburn zone, the reburn fuel fraction and the reburn coal fineness on NOx reduction efficiency and unburned carbon in fly ash. The results indicate that the NOx reduction efficiency reaches the largest value when the relative height of reburn nozzles is about 0.21 and the stoichiometric ratio is between 0.8 and 0.9 in reburn zone; NOx reduction efficiency increases with reburn zone length, reburn fuel fraction and the decrease of reburn coal particle size; the smaller the coal particle size is, the better the burnout performance of coal is.