GAS FUEL-POWERED HOPPER

Based on the hopping principle, a miniature gas fuel-powered hopper is designed and manufactured. According to thermodynamic analysis, the pressure-displacement curve in the combustion chamber after ignition is obtained through iterative calculation, then the work on the cylinder done by high-pressure gas is calculated and the initial hopping velocity of the hopper is obtained. The wireless control system is developed to realize the tele-control of the hopper, including fuel injection and ignition. Experimental results agree well with analytical results. The hopper has a jumping ability of height 2.2 m and distance 3.5 m, and it is more than 14 times its dimension.

Particle size segregation in hopper at a bell-less top blast furnace with parallel hoppers

Owing to a certain angle existing between a belt conveyor and the parallel hoppers,and the hoppers localizing away from the centerlines of a blast furnace,particles size segregation is likely to happen in a bell-less top blast furnace with parallel hoppers.Mastering the law of particles size segregation in hoppers could help to choose better charging parameters and optimize production and technical indices.As for the previous works on burden segregation at a bell-less top blast furnace with parallel hoppers,more attention was paid to the falling point segregation and the circumferential mass flow segregation while charging from the tilting chute,but ignoring the particle size segregation in burden hoppers as burden falls from a belt conveyor,which is the right basis of analyzing the former,and plays a significant role in controlling the gas distribution in the blast furnace.The present work takes ternary mixtures of coke in three different particle sizes to simulate the size segregation of the coke charged into the hoppers by experiments.The effect of the main striking point on size segregation is also investigated.The research shows that there exists a good linear relation between segregation coefficient k and the dimensionless main striking point when using the equation C = C_0~k to express the degree of size segregation in hoppers.The linear relation is proposed for the first time and provides a new way to predict the size segregation in hoppers,which forms a theoretical basis and technical support for reducing the size segregation degree in hoppers.

Burden Distribution for Bell-Less Top With Two Parallel Hoppers

The circumferential burden distribution of bell-less top with two parallel hoppers was analyzed to obtain the expressions of burden flux and uneven ratio. The four-batch feeding spirally with two parallel hoppers was proposed to realize even burden distribution by uneven flux, ensuring reasonable distribution of BF gas and effective usage of heat energy and chemical energy of gas as well as stable BF production with higher quality and lower consumption.

Flow Behaviors of Non-spherical Granules in Rectangular Hopper

Flow behaviors of four kinds of granular particles(i.e. sphere,ellipsoid,hexahedron and binary mixture of sphere and hexahedron) in rectangular hoppers were experimentally studied. The effects of granular shape and hopper structure on flow pattern,discharge fraction,mean particle residence time and tracer concentration distribu-tion were tested based on the visual observation and particle tracer technique. The results show that particle shape affects significantly the flow pattern. The flow patterns of sphere,ellipsoid and binary mixture are all parabolic shape,and the flow pattern shows no significant difference with the change of wedge angle. The flowing zone be-comes more sharp-angled with the increasing outlet size. The flow pattern of hexahedron is featured with straight lines. The discharge rates are in increasing order from hexahedron,sphere,binary mixture to ellipsoid. The dis-charge rate also increases with the wedge angle and outlet size. The mean particle residence time becomes shorter when the outlet size increases. The difference of mean particle residence time between the maximum and minimum values decreases as the wedge angle increases. The residence time of hexahedron is the shortest. The tracer concen-tration distribution of hexahedron at any height is more uniform than that of binary mixture. The tracer concentra-tion of sphere in the middle is lower than that near the wall,and the contrary tendency is found for ellipsoid particles.

A numerical study of dynamics in thin hopper flow and granular jet

The dynamics of granular material discharging from a cuboid but thin hopper,including the hopper flow and granular jet,are investigated via discrete element method(DEM)simulations.The slot width is varied to study its influence on the flow.It is found the flow in the cuboid hopper has similarity with the flow in two-dimensional(2D)hopper.When the slot width is large,the flowrate is higher than the predicted value from Beverloo’s law and the velocity distribution is not Gaussian-like.For granular jet,there is a transition with varying slot width.For large slot width,there is a dense core in the jet and the variations of velocities and density are relatively small.Finally,the availability of continuum model is assessed and the results show that the performance with large slot width is better than that with small slot width.

Discharge flow of granular particles through an orifice on a horizontal hopper:Effect of the hopper angle

We experimentally investigate the effect of the hopper angle on the flow rate of grains discharged from a twodimensional horizontal hopper on a conveyor belt.The flow rate grows with the hopper angle,and finally reaches a plateau.The curve feature appears to be similar for different orifice widths and conveyor belt-driven velocities.On the basis of an empirical law of flow rate for a flat-bottom hopper,we propose a modified equation to describe the relation between the flow rate and hopper angle,which is in a good agreement with the experimental results.

Influence of an inserted bar on the flow regimes in the hopper

We investigated the influence of an inserted bar on the hopper flow experimentally.Three geometrical parameters,size of upper outlet D1,size of lower outlet D0,and the height of bar H,are variables here.With varying H we found three regimes:one transition from clogging to a surface flow and another transition from a surface flow to a dense flow.For the dense flow,the flow rate follows Beverloo’s law and there is a saturation of inclination of free surfaceθ.We plotted the velocity field and there is a uniform linear relation between the particle velocity and depth from the free surface.We also found that the required value of D_(1) to guarantee the connectivity of flow is little smaller than D_(0).For the transition from a surface flow to a dense flow,there is a jump of flow rate and the minimumθfor flowing is two degrees larger than the repose angle.

Dynamical Study of Granular Flow through a Two-Dimensional Hopper

The mass flow rate of a granular flow through an aperture under gravity is a long-standing challenge issue in physical science. We show that for steady flow field close to laminar flow, the dynamical equations together with the continue equation and Mohr-circle description of the stress are closed, and hence solvable. In a case of streamline guided by the two-dimensional hopper, we obtain a consistent condition and use it to determine the stress and the velocity distribution. Our result indicates that 3/2 power scaling behavior is recovered with a coefficient C(μ,α) being a function of frictional coefficient and the hopper angle. It is found that the predicted coefficient C(μ,α) is compatible with previous studies.

EXPERIMENTAL STUDY ON REDUCING ADHESION IN COAL HOPPER BY SURFACE ELECTRO-OSMOSIS

The adhesion mechanics of coal and the behavior of the coal adhesion to the hopper are analyzed. A model coal hopper is developed, and the model experiments are made by using the surface electro osmosis technology according to the processing conditions. The parameters of the surface electro osmosis technology are optimized by the method of orthogonal polynomial regression designing. The result shows that the surface electro osmosis technique is one of the good methods to solve the adhering problem of coal to the coal hopper in transfer piping.

Contact toxicities of imidacloprid on rice brown plant hopper(Nilaparvata lugens Stal)

Rice brown planthopper (BPH) (Nilaparvata lugens Stal, ) which occurs 4 generations within one year in Jiangsu Province has become a serious pest and causes loss of yield on rice every year in this region. The contact toxicities of imidacloprid and methamidophos to rice BPH were tested by means of immerse topical application method and a field trial from 1993 to 1994. A randomized complete design was laid out in 6 treatments with three replications.

The impacts of timing and insecticides at early stage of late rice on the population development of brown plant hopper(BPH)

Field experiments were carried out in northern Zhejiang Province. Three insecticides (methamidophos,Shachongshuang and triazophos) were used to control the rice leaffolder Cnaphalocrocis medinalis and rice striped stemborer Chilo suppressalis in rice fields during 18—27 days after transplantating. The impacts of timing and insecticides on the population development of brown planthopper Nilaparavata lugens was surveyed by direct counting on the plants or by tapping method.

天鲲号绞吸挖泥船挖岩作业配套船舶技术研究

随着全球经济增长和疏浚业的扩大,大型绞吸挖泥船已成为这一领域的关键装备。文章专注于提升超大型绞吸挖泥船“天鲲号”的效能。通过分析该船在挖岩工程中的挑战,引入了“挖-运分离”的高效物流策略。为实现这一目标,建议开发一艘专门与天鲲号配套使用的开体式耙吸挖泥船。文章详细讨论了开体式耙吸挖泥船在主尺度和舱容、快速靠泊、泥舱结构和强度、疏浚系统和船舶布局等方面与天鲲号的匹配问题。提出了一个新颖的开体式耙吸挖泥船方案,能够完全满足配合天鲲号挖岩装驳和运输的需求,实现“挖-运分离”物流策略;能够开展后期扫浅挖泥作业,减少天鲲号的占用期,从而显著提升整体经济效益。

基于不同标准的煤炭漏斗车车体焊缝疲劳寿命研究

利用接触非线性分析技术,基于AAR标准的名义应力法和ASME标准的结构应力法研究煤炭漏斗车车体焊缝的疲劳问题。首先,建立漏斗车重载车体强度分析模型,利用修正D-P本构模型的实体单元模拟散粒煤、接触单元模拟散粒煤与车体结构的作用,并通过主要载荷作用下车体静强度试验结果验证车体仿真分析结果,应力最大误差小于15%。其次,运用名义应力法,在标准和实测载荷谱下分析车体焊缝疲劳寿命,结果表明:端墙与端漏斗板焊缝寿命最短,为2.72×10^(6)km;基于标准纵向载荷谱的焊缝寿命小于基于实测的计算结果,表明标准的纵向载荷谱相对恶劣。最后,在标准中100t漏斗车重车心盘载荷谱和实测纵向载荷谱下运用结构应力法对车体焊缝进行应力与寿命分析。结果表明:基于结构应力法的焊缝疲劳寿命不及基于名义应力法的疲劳寿命,主要原因是结构应力法的疲劳性能参数适用于各类接头形式,且分析承载复杂焊缝时考虑了面内剪切结构应力的影响。因此,对接头几何形状和应力状态复杂的车体从板座及底架区域的焊缝建议采用结构应力法对其进行疲劳寿命分析。

供丝机烟丝束线性堆叠原理分析与应用

为了进一步降低ZJ112卷接机组的卷烟产品空头剔除率,通过对几种主要卷烟机型供丝装置结构、供料及成形工艺原理的研究分析,并结合废烟剔除情况,分析揭示的原理为烟丝在供丝机内从料仓到流化床的平行推进输送原理;烟丝从流化床到吸风室导轨的线性堆叠成形原理。发现了供丝机内在烟丝输送方面与空头形成相关的两个因素,设计应用的改进方案为设计安装新型螺旋绞龙底部凹口护板与延板组件;延长料仓内吸风管的长度,合理设置吸风管口在吸风腔内的位置。改进后,基本消除了回丝被重复性削刷而增加造碎劣化的问题,改善了成品烟支内的烟丝结构质量,降低了产品空头剔除率,提升了吸丝成形工艺过程控制水平。

基于应对土壤污染的优化淋洗技术研究

随着土壤污染问题的愈发严峻,土壤淋洗技术作为应用最为广泛的土壤修复技术之一,正受到广泛聚焦。本文通过对ALLU斗与异位土壤淋洗技术结合处理污染土的研究,从技术路线、修复车间剖面布置、平面布置3个维度进行设计,以某氰化物污染地为实验对象进行两次现场试验。实验结果表明了研究提出的ALLU斗与异位土壤淋洗技术结合处理污染土可行。

料斗倾角对气基竖炉布料过程中物料流动及分布的影响

球团矿离开料斗时的颗粒偏析会影响其在气基竖炉内的分布,分布不合理将影响还原气的利用率建立20°~70°倾角的料斗、导料管、溜槽、气基竖炉三维模型,基于离散元法研究物料从料斗到气基竖炉布料过程中的流动和分布结果表明:排料时,20°~25°倾角的料斗内炉料流型均为整体流,30°~55°倾角的料斗内炉料流型均为混合流,60°~70°倾角的料斗内炉料流型均为漏斗流漏斗流促使料层形成快速流动的中心通道,大颗粒会更早地离开料斗进入炉内,在落点区域堆积,导致料斗内大颗粒负偏析、竖炉内落点区域大颗粒正偏析20°~35°倾角的料斗布料后,炉内孔隙率偏差分布在000383~000468,倾角增大,孔隙率偏差增大改变炉料-料斗静摩擦系数、炉料批重、料斗半径等参数,发现料斗倾角是影响布料过程和结果的主要因素,孔隙率偏差仍随料斗倾角的增大而增大。

基于离散元与有限元耦合的料斗衬板磨损分析

针对转运系统转载物料过程中料斗衬板的磨损影响运输效率的问题,改用新型钢基陶瓷复合衬板来代替传统耐磨钢,采用离散元法(distinct element method,DEM)描述颗粒物料运动过程,通过Archard磨损模型分析预测不同工况条件下衬板磨损规律,并通过磨损规律和磨损特征验证了磨损模型的合理性。基于DEM的有限元法(finite element method,FEM)耦合方法分析了衬板应力与变形特性。研究结果表明:料斗衬板的最大磨损深度随颗粒度增大而减小,随传送带带速、衬板安装高度、衬板安装倾角的增大而增大。结合实际来看,衬板在粒径25mm、带速2.8m/s、高度3000mm、角度60°的工况下磨损最小。铁矿石散料对衬板的摩擦和冲击作用造成的应力较大的位置主要集中在衬板连接的螺栓孔周围,磨损最严重的位置多为颗粒与衬板优先接触区域,因此,为了降低应力集中,应该在衬板连接处加强螺栓孔的强度并进行圆角设计。

Vibration induced flow in hoppers:DEM 2D polygon model

A two-dimensional discrete element model （DEM） simulation of cohesive polygonal particles has been developed to assess the benefit of point source vibration to induce flow in wedge-shaped hoppers. The particle-particle interaction model used is based on a multi-contact principle. The first part of the study investigated particle discharge under gravity without vibration to determine the critical orifice size （Bc） to just sustain flow as a function of particle shape. It is shown that polygonal-shaped particles need a larger orifice than circular particles. It is also shown that Bc decreases as the number of particle vertices increases. Addition of circular particles promotes flow of polygons in a linear manner. The second part of the study showed that vibration could enhance flow, effectively reducing Bc. The model demonstrated the importance of vibrator location （height）, consistent with previous continuum model results, and vibration amplitude in enhancing flow.

浸出器负压强制沥干装置分析

浸出器是浸出制油的重要设备,提高浸出器的性能不但能降低粕中残油,而且能够减轻后续高温脱溶或低温脱溶的负荷,进而节省蒸汽消耗。浸出器负压强制沥干装置是用不同的方式使沥干封闭油斗为负压,强制沥干湿粕物料中的低浓度混合油,达到湿粕含溶量进一步降低的目的。为了降低湿粕含溶量,提高企业经济效益,分别介绍了用液环真空泵、蒸汽真空泵、负压风机抽取浸出器沥干段负压装置的工艺,特点和适用范围,同时也阐述了不同类型的常用浸出器强制沥干封闭油斗的方式,最后对沥干效果和经济效益进行综合分析。通过浸出器负压强制沥干装置可以有效降低湿粕含溶量,在高温蒸脱时节省蒸汽消耗量进而为企业带来一定的经济效益。

Flow behavior of non-spherical particle flowing in hopper

Ellipsoidal particles flowing in the hopper were simulated by using the discrete element method （DEM）, and described by the multi-element method. The contact detection algorithm and equations for ellipsoidal particle motion in hopper were developed. And the simulation results were confirmed by experiment. Additionally, the mass flow rate, pressure distribution and velocity distribu- tion of two kinds of particles were examined. The results show that the mass flow rate of ellipsoidal particles is smaller than that of spherical particles. There is a maximum value of pressure drop at the top of the junction. Besides, the pressure drop decreases with the discharging time increasing. The velocity of spherical particle is larger than that of ellipsoidal.