焦化厂回收易地大修暨脱硫脱氰工程简介

本文叙述了国内先进的煤气净化工艺和氨、硫回收装置，净化了焦炉煤气，减少了环境污染，改善了硫铵质量，增加了硫磺新产品，提高了生产管理水平，确保了安全生产。     

焙烧炉天然气燃烧自动控制系统的研究与应用

介绍了炭素焙烧炉燃烧系统的改造,新型控制系统的功能介绍、使用效果和效益分析,通过改造真正实现了清洁生产,达到了节能效果,改善了工艺水平,提高了产品质量,降低了生产成本,提高了生产效率,改善了工作环境。     

抓斗吊车常见故障与解决措施

分析了20 t桥式抓斗起重吊车常见故障及原因,采取了相应的解决措施,从根本上杜绝了吊车的常见故障、节约了备件、降低了生产成本、减轻了维修人员劳动强度及提高了企业的经济效益.     

延长锰硅合金矿热炉出铁口寿命的初步探讨

阐述了锰硅合金矿热炉出铁口损坏的机理。有针对性的采用了一些维护措施，延长了出铁口的使用寿命，改善了炉况，提高了产量，降低了生产成本，获得了一定的经济效益。     

提高烧结配料生石灰消化除尘效果的生产实践

通过对烧结配料生石灰消化除尘系统进行改造,提高了除尘效果,同时稳定了生石灰配加量和消化打水量;充分回收利用了消化蒸汽和二次扬尘,减少了资源浪费,提高了消化水温,进一步强化了生石灰消化作用,提高了混合料制粒效果和混合料料温;极大地改善了配料室工作环境,有效降低了检修劳动强度,提高了设备作业率。     

控冷电磁站搬迁方案的改进

通过大量的调查研究，查清了电磁站内渗漏水的缺陷，提出了解决方案和具体操作方法，改变了原定的搬迁方案，不仅彻底地消除了缺陷，还节约了大修费，缩短了工期，为生产创了可观的效益。     

冷床上卸钢液压系统改造

对原液压系统设计及使用中存在的问题 ,进行了分析、计算 ,找出了原因所在 ,提出了改造方案 ,从而有效地提高了液压系统的稳定性 ,减少了设备故障 ,降低了维护强度 ,提高了工作效率。     

ZDRH-2000智能集中润滑系统在435m~2烧结机上的应用

邯钢435m2烧结机采用了ZDRH-2000智能集中润滑系统克服了传统润滑的弊端;降低了能源的消耗;减少了备品备件的消耗;大大减少了设备日常维护的工作量;提高了设备生产效率;降低了生产成本。     

武钢KR脱硫工艺改进

介绍了武钢炼钢总厂二分厂KR脱硫工艺的改进。通过优化了脱硫剂的成分,使脱硫效果得到明显改善,脱硫剂单耗大幅降低;优化了搅拌、扒渣工艺并采取底吹技术,大幅减少了扒渣过程中的金属损失;改进了搅拌器形状和制作工艺,提高了搅拌器寿命,并减少了修补料消耗;开发了脱硫自动控制模型,提高了生产效率,改善了操作环境。     

安钢250／300轧钢机组加热炉循环水工程改造

安钢２５０／３００轧钢机组加热炉一次性水冷却改为软水闭路循环水冷却系统,保证了政党生产,节约了水资源,减少了外打破常规水量,保护了生态环境,同时降低了加热炉的故障率,减少了维修费用,提高了经济效益。     

New Orleans Levee System Performance during Hurricane Katrina: London Avenue and Orleans Canal South

Hurricane Katrina was one of the worst natural disasters in U.S. history. The effects of the hurricane were particularly devastating in the city of New Orleans. Most of the damage was due to the failure of the levee system that surrounds the city to protect it from flooding. This paper presents the results of centrifuge models conducted at Rensselaer Polytechnic Institute and the U.S. Army Corps of Engineers simulating the behavior of the levees at London Avenue North and South that failed during Hurricane Katrina. Those levees failed without being overtopped by the storm surge. Also included are the results of a centrifuge model of one levee section at Orleans Canal South, which did not fail during the hurricane. The key factor of the failure mechanism of the London Avenue levees was the formation of a gap between the flooded side of the levee and the sheetpile. This gap triggered a reduction of the strength at the foundation of the protected side of the levee. The results are fully consistent with field observations.     

Reliability-Based Optimal Design of Truss Structures Using Particle Swarm Optimization

In this work, the particle swarm optimization method is employed for the reliability-based optimal design of statically determinate truss structures. Particle swarm optimization is inspired by the social behavior of flocks (swarms) of birds and insects (particles). Every particle’s position represents a specific design. The algorithm searches the design space by adjusting the trajectories of the particles that comprise the swarm. These particles are attracted toward the positions of both their personal best solution and the best solution of the swarm in a stochastic manner. In typical structural optimization problems, safety is dealt with in a yes/no manner fulfilling the set of requirements imposed by codes of practice. Considering uncertainty for the problem parameters offers a measure to quantify safety. This measure provides a rational basis for the estimation of the reliability of the components and of the entire system. Incorporating the reliability into the structural optimization framework one can seek a reliability-based optimal design. For the problems examined herein, the reliability indexes of the structural elements are obtained from analytical expressions. The structure is subsequently analyzed as a series system of correlated elements and the Ditlevsen bounds are used for the calculation of its reliability index. The uncertain-random parameters considered in this work are the load, the yield-critical stress; and the cross sections of the elements. The considered design variables of the optimization problem are the cross-sectional areas of the groups, which control the size of the truss, and the heights and lengths that control the shape of the truss. The results of the optimization are presented for a 25-bar truss and a 30-bar arch and the robustness of the optimization scheme is discussed.     

Addition of Cobalt to Lead Anodes Used for Oxygen Evolution—A Literature Review

A review of the literature dealing with the effect of cobalt on lead-based anodes for oxygen evolution during electrolysis of sulfuric acid solutions verifies that the presence of cobalt at the anode–electrolyte interface, either as constituent of the anode material or as ions in the electrolyte, catalyzes the evolution of oxygen and reduces the corrosion of the anodes and the contamination by lead of metal cathodes produced during electrowinning. However, due to harmful effects of cobalt ions on the cathodic reaction in some processes, these benefits are limited to the electrowinning of copper. Efforts to develop a way of introducing cobalt at the anode–electrolyte interface without interfering with the cathodic reactions are reviewed in this paper. The use of lead–cobalt alloy anodes has had limited success due to issues arising from the low solubility of cobalt in lead, segregation during casting of the alloys, and nonuniform distribution of cobalt which affects the integrity of the anodes. This has been overcome in part lately by inclusion of cobalt into only the surface layer of a lead or lead alloy substrate, by thermal treatment of a cobalt salt to form a catalytic cobalt oxide surface species, or by electrodeposition of composite lead–cobalt oxide anodes. The last approach in particular has been actively investigated by several groups, but to our knowledge it is yet to find application in the industry. The review also critically examines the likely reaction mechanisms involved.     

Pseudostatic Coefficient for Use in Simplified Seismic Slope Stability Evaluation

Pseudostatic slope stability procedures are commonly used in engineering practice. However, the selection of the seismic coefficient employed in the analysis is often based on precedence without due consideration of the amount of seismic displacement that constitutes satisfactory performance for each particular project and without incorporating the vastly different seismic exposure for sites around the world. In this Note, a rational basis for selecting the seismic coefficient is presented. The proposed procedure requires that the engineer establishes the project-specific allowable level of seismic displacement. The seismic response characteristics of the slope are represented by the fundamental period of the potential sliding mass, and the site-dependent seismic demand is characterized by the 5% damped elastic design spectral acceleration at the degraded period of the potential sliding mass. The level of uncertainty in the estimates of the seismic demand and displacement can be handled through the use of different percentile estimates of these values. With the proposed equations, the engineer can properly incorporate the amount of seismic displacement judged to be allowable and the seismic hazard at the site in the selection of the seismic coefficient.     

Reliability-Based Design for External Stability of Mechanically Stabilized Earth Walls

A two-phase approach was used to develop a reliability-based design (RBD) method for external stability of mechanically stabilized earth (MSE) walls. In the first phase, a parametric study was conducted using Monte Carlo simulation to identify parameters that affect the probability of external failure of MSE walls. Three modes of failure were considered: sliding, overturning, and bearing capacity. External stability was assessed by treating the reinforced soil as a rigid mass using the same procedures employed for conventional gravity-type wall systems. Results from the parametric study indicate that the mean and coefficient of variation of the backfill friction angle are significant for sliding, the mean and coefficient of variation of the friction angle of the backfill and coefficient of variation of the unit weight of the backfill are significant for overturning, and the mean and coefficient of variation of the friction angle of the foundation soil and the mean of the backfill friction angle are significant for bearing capacity. In the second phase, a series of additional simulations was conducted where the significant parameters identified in the parametric study were varied over a broad range. Results of these simulations were used to develop a set of RBD charts for external stability of MSE walls. A comparison indicates that similar reinforcement lengths are obtained using RBD and conventional methods and that the inherent probability of external failure in conventional deterministic design is ? 0.001. This probability of external failure is similar to inherent probability of failure reported by other investigators for similar geotechnical structures.     

Influence of the chromium and ytterbium co-doping on the photoluminescence of zinc selenide crystals

The luminescent properties of ZnSe, ZnSe：Cr（0.05 at.% Cr）, ZnSe：Yb（0.03 at.% Yb） and ZnSe：Cr：Yb（0.05 at.% Cr, 0.05 at.% Yb） crystals, doped during the growth process by the chemical vapor transport method, were studied within the temperature interval of 6–300 K. At the 6 K temperature in the visible spectral range 2 bands were observed： a band in the excitonic spectral region and a band of self-activated luminescence. It was shown that co-doping of zinc selenide crystals with the chromium and ytterbium led to the combination of the impurities influence on the photoluminescent properties. At the liquid helium temperature in the middle infrared range of the spectra of the ytterbium and chromium co-doped crystal a band with the maximum localized at 1.7μm was observed, which was overlapped with a complex band in the middle-IR spectral range, characteristic for the chromium doped ZnSe crystals. On the basis of obtained data an interaction mechanism of the chromium and ytterbium co-doping impurities was proposed. Guided by the existent model of the ytterbium ion incorporation in the selenide sublattice of the ZnSe crystals, an assumption about stabilization of single charged chromium ions in the zinc sublattice crystal nodes, by means of formation of the local charge compensating clusters, was made. It was assumed that the resonant energy transfer from one chromium ion to another,which led to the concentration quenching of the IR emission in the ZnSe：Cr PL spectra, would lead to the broadening of the IR emission in the spectra of ytterbium and chromium co-doped zinc selenide crystals.g     

Fluidization in an Anaerobic EGSB Reactor: Analysis of Primary Wakes and Modeling of Sludge Blanket

Fluidization of biogranules in an anaerobic expanded granular sludge bed (EGSB) reactor is stochastic in nature and it is a function of the size distribution and the frequency of generation of flow-through gas bubbles in the reactor. Other factors that contribute to the distribution of granules along the height of the reactor are the settling characteristics of granules and the fluid velocity. A simulation was conducted in a test column to obtain a relationship between the flow-through gas and granules at different heights along the column. This relationship was combined with the pattern of gas flow through an identical EGSB reactor to create a model to predict the concentration of granules at different heights along the reactor. The model can predict well the stochastic nature of the axial distribution of granules but underestimates the number of granules at different heights. The reasons for such deviations are explained. The pattern of granule shedding from the primary wake associated with spherical cap bubbles and terminal velocities of bubbles have also been studied and modeled to estimate the maximum height of ascent of granules under isolated spherical cap bubbles. The results of this model agreed well with the experimental observations.     

Approach to Separate Sand from Gravel for Bed-Load Transport Calculations in Streams with Bimodal Sediment

The bed material found in gravel-bed streams is nonuniform in terms of grain size and can typically be classified as unimodal or bimodal. The latter type of sediment distribution is usually represented by two modes, one of sand size and another of gravel. For this case, the movement of one mode becomes nonlinearly influenced by the other. As a result, the presence of the two modes in a bimodal material complicates the calculation of bed-load transport rates. The present study proposes an approach to separate the calculation of bed-load transport rates for bimodal materials into two independent fractions of sand and gravel, thereby rendering the bed sediment into two unimodal components. This approach is accomplished by decoupling the two fractions through scaling the reference Shields stresses of the sand and gravel modes to match the value of the mode of unimodal materials. Consequently, the contribution of each fraction to bed load can be estimated using a suitable relation derived for unimodal materials. Laboratory and field bed-load data available in the literature are used to examine the validity of the overall approach.     

Artificial Ground Freezing of Fully Saturated Soil: Viscoelastic Behavior

The transport and mechanical properties of saturated soil drastically change when temperatures drop below the freezing temperature of water. During artificial ground freezing, this change of properties is exploited in order to minimize deformations during construction work and for groundwater control. Whereas for the latter only the size of the frozen-soil body is relevant, which is obtained by solving the thermal problem, the design of the ground-freezing work for support purposes requires information about the mechanical behavior of frozen soil. In addition to the quantification of the improvement of mechanical properties during freezing, information about the dilation associated with the 9% volume increase of water during freezing is required in order to assess the risk of damage to surface infrastructure caused by frost heave. In this paper, a micromechanics-based model for the prediction of both the aforementioned phase-change dilation and the elastic and viscous properties of freezing saturated soil is presented. Hereby, the macroscopic material behavior is related to the behavior of the different constituents such as soil particles, water, and ice. Combined with the solution of the thermal problem, the proposed model provides the basis for predictions of the performance of support structures composed of frozen soil.