Porosity distribution of moving burden layers in the blast furnace throat

Granular Matter - The shear flow behaviors of granular materials exist widely in natural events. Ring shear tests based on the discrete element method were carried out to study the effects of...     

Modeling of solids flow in a blast furnace by the streamline method

The streamline method is applied to simulate solids flow in a blast furnace by superposing potential sources at the lower parts of the furnace model onto a viscous down-flow stream. This superposition yields a stationary zone at the bottom to simulate the so-called ‘deadman’ in a blast furnace. A boundary layer is added on the deadman to satisfy the condition of no slipping there. As a result, analytic expressions for solids velocities have been obtained and the experimental results could be satisfactorily predicted, i.e. there exists a higher velocity in the flow region between the side wall and the central deadman along the depth in a three-dimensional cold model of a blast furnace with coarse polystyrene beads.     

Knock characteristics of dual-fuel combustion in diesel engines using natural gas as primary fuel

This paper investigates the combustion knock characteristics of diesel engines running on natural gas using pilot injection as means of initiating combustion. The diesel engines knock under normal operating conditions but the knock referred to in this paper is an objectionable one. In the dual-fuel combustion process we have the ignition stage followed by the combustion stage. There are three types of knock: diesel knock, spark knock and knock due to secondary ignition delay of the primary fuel (erratic knock). Several factors have been noted to feature in defining knock characteristics of dual-fuel engines that include ignition delay, pilot quantity, engine load and speed, turbulence and gas flow rate     

Recycling of steel slag as an alkali activator for blast furnace slag: geopolymer preparation and its application in composite cement

Clean Technologies and Environmental Policy - The recycling–utilization rate of steel slag in China is less than 30%. Steel slag is rich in CaO and can produce the Ca(OH)2 after hydration,...     

塑料、垃圾成为德州水泥炉的燃料

来自从美国化学理事会和奥斯汀德克萨斯大学的最新一份研究报告(PDF)表明,从不可回收的废塑料和其它废物中生成的燃料可以用于电力能源密集型商业和工业使用。     

Effect of the PLAZMAZER plasma ignition system on the fuel combustion regimes in combustion chambers of engines

An economically efficient method of combatting toxic products of incomplete fuel combustion in engines and other movable and stationary power installations by means of pulsed automatic control of the ignition and combustion processes carried out by the PLAZMAZER system is proposed. A new concept of the occurrence of motor knock in internal combustion engines with external carburetion, the stiff operating mode of diesel engines, erosion of turbine blades, burn-out of combustion-chamber and exhaust-line elements, and jet engine compression stalling are presented.     

Modelling the combustion of high-ash content solid fuel in circulating systems

G. M. Krzhizhanovski Institute of Power Engineering, Moscow. Translated from Inzhenerno-Fizicheski Zhurnal, Vol. 62, No. 3, pp. 427–435, March, 1992.     

Modification of phase evolution in alkali-activated blast furnace slag by the incorporation of fly ash

The microstructural evolution of alkali-activated binders based on blast furnace slag, fly ash and their blends during the first six months of sealed curing is assessed. The nature of the main binding gels in these blends shows distinct characteristics with respect to binder composition. It is evident that the incorporation of fly ash as an additional source of alumina and silica, but not calcium, in activated slag binders affects the mechanism and rate of formation of the main binding gels. The rate of formation of the main binding gel phases depends strongly on fly ash content. Pastes based solely on silicate-activated slag show a structure dominated by a C–A–S–H type gel, while silicate-activated fly ash are dominated by N–A–S–H ‘geopolymer’ gel. Blended slag-fly ash binders can demonstrate the formation of co-existing C–A–S–H and geopolymer gels, which are clearly distinguishable at earlier age when the binder contains no more than 75 wt.% fly ash. The separation in chemistry between different regions of the gel becomes less distinct at longer age. With a slower overall reaction rate, a 1:1 slag:fly ash system shares more microstructural features with a slag-based binder than a fly ash-based binder, indicating the strong influence of calcium on the gel chemistry, particularly with regard to the bound water environments within the gel. However, in systems with similar or lower slag content, a hybrid type gel described as N–(C)–A–S–H is also identified, as part of the Ca released by slag dissolution is incorporated into the N–A–S–H type gel resulting from fly ash activation. Fly ash-based binders exhibit a slower reaction compared to activated-slag pastes, but extended times of curing promote the formation of more cross-linked binding products and a denser microstructure. This mechanism is slower for samples with lower slag content, emphasizing the correct selection of binder proportions in promoting a well-densified, durable solid microstructure.     

醋酸盐-葡萄糖体系溶液燃烧合成尖晶石型LiMn2O4研究

以醋酸锂和醋酸锰为原料,葡萄糖为燃料,研究和分析了在550℃溶液燃烧合成尖晶石型LiMn2O4物质的过程、葡萄糖用量对合成LiMn2O4物质的影响,并从热力学的角度探讨了其过程.实验结果表明,仅有醋酸锂和醋酸锰的溶液燃烧合成反应为无焰燃烧,加入燃料后为有焰燃烧;在醋酸盐体系中加入葡萄糖为燃料,燃烧产物LiMn2O4的结晶程度随葡萄糖量增多而逐渐提高,但燃料太多,会使LiMn2O4发生部分热分解.当x(Li):x(Mn):x(glucose)=1:2:x,x=1.0～2.0时溶液燃烧合成可得到纯相LiMn2O4物质,x≥3.0得到主晶相为LiMn2O4的产物,x=4.0产物主晶相为贫锂尖晶石Li1-xMn2O4.     

Effects of H2O/Na2O molar ratio on the strength of alkaline activated ground blast furnace slag-ultrafine palm oil fuel ash based concrete

Effects of H₂O/Na₂O molar ratios (MRs) on the developed alkaline activated pozzolanic solid wastes (PMs)-ultrafine palm oil fuel ash (UPOFA) and ground blast furnace slag (GBFS)-were studied by using the constant mass of combined activators (10 M NaOH_aq + Na₂SiO_3aq of silica-modulus (Ms = SiO₂/Na₂O) of 3.3).The free water content (FWC) expressed as FWC/(PMs) varied from 0.02 to 0.1 by mass while the total H₂O/Na₂O MRs ranged from 18.9 to 23.1 The findings revealed that increase in H₂O/Na₂O MRs negatively affects the strength but positively impact the mixture workability (consistency). The microstructural morphology examination using Scanning Electron Microscope coupled with Energy dispersive spectroscopy (SEM + EDS) reveals the contribution of H₂O/Na₂O MRs to the product nature, compactness, and the reactivity of Ca²⁺ and Al³⁺ while Fourier transform infra-red (FTIR) spectroscopy indicates that H₂O/Na₂O ratios contributed to the product amorphousity and carbonation process but sparingly affected its formed polymerized structural units (SiQⁿ(mAl), n = 2 and 3).     

Calculation of the heats of combustion of aromatic hydrocarbons contained in power-generating fuel

The additive method of group contributions is used for the calculation of the heats of combustion of aromatic hydrocarbons of different structures.     

Toxic byproducts from the combustion of varnish wastes based on polyurethane in a laboratory furnace

Varnish wastes based on polyurethane were burnt in a laboratory scale furnace at different residence time of gases and temperatures and with a fuel-rich atmosphere and with an excess of oxygen. The yields of CO, CO(2), six light hydrocarbons (methane, ethylene, etc. ) and 31 semivolatile+volatile compounds (benzene, toluene, naphthalene, dibezofuran, etc.) were determined with stoichiometric factors of the oxygen between 0.6 and 0.9, nominal temperatures of the reactor between 750-1050 degrees C and residence times of the volatiles evolved and formed between 2 and 6 s. The collection of the volatiles evolved was carried out with a Tedlar bag and by XAD-4 resin, comparing the data obtained in both cases. The maximum emission factors or yields of volatiles+semivolatiles were obtained at 850-950 degrees C, with values above 0.5% for benzene, naphthalene, acenaphthylene, phenantrene and fluoranthene. The thermal behaviour of different compounds was analysed. Naphthalene, benzene and toluene were also detected in the excess oxygen runs.     

Calculation of the process of blast wave diffraction in a cylindrical channel

We performed a numerical investigation of the process of transition of a spherical leading front into a plane one in a cylindrical channel. The processes of the collision of reflected shock waves, formation of a nonstationary grating-like structure of flow, and of the overtaking interaction of shock waves are investigated. We found that in the presence of hot gas layers on the walls of the channel a plane head front is not formed.Notation r,z radial and axial coordinates - t time - p pressure - T temperature - u,v radial and axial velocity components - a distance between the planes - b half-distance between the planes - d channel diameter (in experimental data) - R ₀ inital radius of the shock wave front - p ^*(r, z),u ^*(r, z),v ^*(r, z),T ^*(r, z) distributions of pressure, radial, and axial velocity, and temperature at the initial time moment - L length of the zone of formation of a plane front - T ₁,T ₂ temperature of gas in the lower and upper thermal layers - h ₁,h ₂ thicknesses of the lower and upper thermal layers Department of Theoretical Problems of the Russian Academy of Sciences, Moscow Physicotechnical Institute, Moscow. Translated from Inzhernerno-Fizicheskii Zhurnal, Vol. 68, No. 4, pp. 583–588, July–August, 1995.     

Electrochemical properties of LiMn1.5Ni0.5O4 powders synthesized by solution combustion method: Effect of CTAB as a fuel

LiMn_1.5Ni_0.5O₄ powders were prepared by solution combustion synthesis using cetyltrimethylammonium bromide (CTAB) as fuel. The spinel LiMn_1.5Ni_0.5O₄ powders were directly formed due to the low decomposition rate as characterized by thermal analysis and X-ray powder diffraction techniques. The microstructure observed by electron microscopy showed the particle size increased from 10 to 90 nm with the increase of fuel amount. However, the specific surface area decreased from 211 to 105 m² g⁻¹. The highest discharge capacity at 1C obtained for the LiMn_1.5Ni_0.5O₄ powders synthesized at low fuel contents, which retain a capacity of 90 mAh g⁻¹ after 30 cycles due to the lower electrode resistance as confirmed by electrochemical impedance analysis. The high electrode kinetics was attributed to the small particle size and high specific surface area.     

An approach to simulate the motion of spherical and non-spherical fuel particles in combustion chambers

The objective of this paper is to identify a numerical method to simulate motion of a packed or fluidized bed of fuel particles in combustion chambers, such as a grate furnace and a rotary kiln. Therefore, the various numerical methods applied in the areas of granular matter and molecular dynamics were reviewed extensively. As a result, a time driven approach was found to be suited for the numerical simulation of particle motion in combustion chambers. Furthermore, this method can also be employed to moving boundaries which are required for the present application e.g. travelling grate. The method works in a Lagrangian frame of reference, which uses the position and orientation of particles as independent variables. These are obtained by time integration of the three-dimensional dynamics equations derived from the classical Newtonian approach for each particle. This includes the keeping track of all forces and momentums acting on each particle at every time step. Viscoelastic contact forces include normal and tangential components with viscoelastic models for energy dissipation and friction. The particle shapes are approximated by spheres and ellipsoids with a varying size and ratio of the semi-axis accounting for the variety of particle geometries in a combustion chamber. For these shapes the overlap of particles during contact is expressed by a polynomial of 4th order in the two-dimensional case and a polynomial of 6th order in the three-dimensional case. A new algorithm to detect two-dimensional elliptical particle contact with sufficient accuracy was developed. It is based on a sequence of coordinate transformations and has demonstrated its reliability in numerous applications. Finally, the method was applied to simulate the motion of spherical and elliptical particles in a rectangular enclosure, on a travelling grate, and in a rotary kiln. Received: 16 November 2001