新钢锰烧车间带冷除尘系统的改造

1 前言新钢一铁分厂锰烧车间带冷系统原设计用脉冲袋式除尘器对冷矿筛分及运输系统进行除尘。自1983年12月投入运行以来,经生产实践证明,除尘效果很差,尤其是成品2~#及返矿1~#胶带机通廊灰尘很大,环境恶劣,     

汉钢2×240m~2烧结机除尘系统改造

针对汉钢烧结№.1、№.2机尾袋式除尘系统及成品筛分袋式除尘系统除尘效果差、滤袋寿命短等问题,在实地考察和分析的基础上,提出了三个除尘系统仅有一台除尘器扩容改造,其余两台除尘器和全部风机、电机完全利旧的改造方案。通过采用先进的烟气预处理、管网设计、阻力平衡等技术,最终实现了改造目标,为今后同类系统改造提供了借鉴。     

扎兰德钢铁公司250万吨氧化球团工程设计特点

介绍了伊朗扎兰德钢铁有限公司250万吨氧化球团工程设计特点,该工程采用链箅机-回转窑工艺,主要生产车间包括配料室、混合室、造球室、链箅机-回转窑-环冷机、成品筛分、成品堆场等。工程投产后各项功能指标均达到设计要求。     

金渠金矿破碎车间除尘设备的改造及应用

选矿厂破碎车间普遍存在粉尘现象。介绍了金渠金矿破碎车间湿式除尘系统的设计、试运行及存在问题;提出了设备改造方案。改造运行效果表明,破碎车间操作岗位的粉尘浓度1mg／m^3,除尘系统排放的粉尘浓度80mg／m^3,达到了国家标准;除尘系统改造提高了除尘效率,改善了作业环境。     

120管除尘器堵塞情况及其处理

我车间烧结抽风系统,设计采用三段除尘方式,第一段是φ1800降尘管,第二段扩大式除尘器(3000×3800×4200降尘室),第三段是120管多管除尘器。各段除尘下来的灰尘,均落入水封拉链机之水封槽内,然后拉入混—1皮带机,送往一次混合室。由于生产工人全车间仅有54人于1974年在马钢一烧培训过,绝大多数未经培训,缺     

鞍钢三烧车间技术改造实践

鞍钢三烧车间采用鼓风带冷—一段筛分新工艺,改热矿为生产冷矿获得成功,成品烧结矿筛分指数小于5 %,投资比常规工艺改造降低48 %。本文重点介绍一段筛分采用的新工艺、新技术、新设备及在生产中的效果。     

提高本钢转炉一次除尘效率的研究与实践

本钢转炉一次除尘系统烟气流量超过设计能力,系统结垢严重,影响转炉一次除尘效果。经过计算原材料产生的烟气量,优化转炉工艺操作,增加石灰筛分工艺减缓结垢速度,提高了转炉除尘效率。     

寒冷地区选矿厂大型振动筛湿式除尘系统研究

寒冷地区某选厂磨浮车间大型振动筛生产过程中产生大量粉尘,为降低岗位粉尘浓度,改善工作环境拟设计施工除尘系统。综合考虑冬季保暖减少换气、半自磨加水降温产生蒸汽、车间生产系统布置、粉尘特性等条件,设计采用高效湿式除尘系统和振动筛整体密闭罩。通过实施前后粉尘检测结果对比分析,说明湿式除尘系统运行效果良好,改善了作业环境,达到了国家环保标准要求。     

锰粉车间除尘粉自动返回工艺改造

针对锰粉车间除尘粉数量大、品级及放电能力低的问题,在原生产工艺的基础上,寻求使除尘粉与成品粉自动充分混合的技术改造措施,并取得明显效果。     

低压脉冲袋式除尘控制系统设计

介绍了某钢厂炼钢车间布袋除尘控制系统。以Simatic S7-400 PLC为核心,采用工业以太网和Profibus-DP技术,控制除尘设备的自动运行;采用变阻力清灰策略控制布袋脉冲清灰,给出阻力目标计算的经验公式;采用模糊控制算法控制除尘室烟气温度。运行实践表明,系统稳定可靠,具有较高的除尘效率和控制精度。     

冶建施工项目效益审计的方法探讨

文章以二冶酒钢项目为研究对象,运用效益审计相关理论,确定其审计任务和目的,采用检查、询问、函证、监盘、计算、分析性复核等效益审计方法,对该项目预算收入的准确性、实际成本的完整性、资金到位的可靠性情况进行核实,找出项目经营中存在的问题,并有针对性地提出一系列的改进意见和建议。     

Preimplantation genetic diagnosis: current status and new developments

Preimplantation genetic diagnosis (PGD) is a very early form of prenatal diagnosis aimed at eliminating embryos carrying serious genetic diseases before implantation. To this end, two major technologies are in use: the polymerase chain reaction (PCR) for monogenic diseases and fluorescent in-situ hybridization (FISH) for chromosomal aberrations. In this review, a number of problems arising from the use of these technologies, as well as their possible solutions and new developments, are discussed. Concerning PCR, the phenomenon of allelic drop-out, as well as methods to reduce this problem, such as fluorescent PCR, are described. The advantages and disadvantages of sperm separation by flow cytometry as an adjunct to sex determination for the avoidance of X-linked disease are discussed. The application of FISH for aneuploidy detection is commented upon and the advances in cell recycling, in which PCR and FISH are combined, are analysed. Finally, diseases for which PGD is currently possible are summarized.     

Development of an analytical equation for calculation of the blast furnace fuel rate

Analytical expressions are developed for calculating the specific fuel rate and the direct reduction rate for the iron blast furnace process as a function of blast conditions as well as other control parameters for the process. These are relevant for carbonaceous as well as hydrogenaceous gases in the system. The equations are based on an oxygen balance and a heat balance for the bottom half of the furnace, separated from the upper half at the location where equilibrium of the gas phase with wustite and iron is assumed to occur and where the temperatures of the gas and solid streams are approximately equal. The mass and heat balances employed are those which are the basis for the classical Rist diagram. Equations were also derived for the constraints of the Carbon-Direct Reduction (C-DRR) diagram, showing that this diagram and the Rist diagram emphasize different variables of the same model. An interpretation of the constraints operating in the diagrams is also given from the point of view of blast furnace operating practice.     

Finite Element Response Sensitivity Analysis of Steel-Concrete Composite Beams with Deformable Shear Connection

The behavior of steel-concrete composite beams is strongly influenced by the type of shear connection between the steel beam and the concrete slab. For accurate analytical predictions, the structural model must account for the interlayer slip between these two components. In numerous engineering applications (e.g., in the fields of structural optimization, structural reliability analysis, and finite element model updating), accurate response sensitivity calculations are needed as much as the corresponding response simulation results. This paper focuses on a procedure for response sensitivity analysis of steel-concrete composite structures using displacement-based locking-free frame elements including deformable shear connection with fiber discretization of the cross section. Realistic cyclic uniaxial constitutive laws are adopted for the steel and concrete materials as well as for the shear connection. The finite element response sensitivity analysis is performed according to the direct differentiation method. The concrete and shear connection material models as well as the static condensation procedure at the element level are extended for response sensitivity computations. Two steel-concrete composite structures for which experimental test results are available in the literature are used as realistic testbeds for response and response sensitivity analysis. These benchmark structures consist of a nonsymmetric, two-span continuous beam subjected to monotonic loading and a frame subassemblage under cyclic loading. The new analytical derivations for response sensitivity calculations and their computer implementation are validated through forward finite difference analysis based on the two benchmark examples considered. Selected sensitivity analysis results are shown for validation purposes and for quantifying the effect and relative importance of the various material parameters in regards to the nonlinear monotonic and cyclic response of the testbed structures.     

Multidimensional Performance Limit State for Hazard Fragility Functions

This paper addresses an alternative methodology to calculate fragility functions that considers multiple limit states parameters, such as combinations of response variables of accelerations and interstory drifts. Limit states are defined using a generalized multidimensional limit states function that allows considering dependencies among limit thresholds modeled as random variables in the calculation of fragility curves that are evaluated as function of the return period. A California hospital is used as example to illustrate the proposed approach for developing fragility curves. The study investigates the sensitivity of the proposed approach for evaluating fragility curves when uncertainties in limit states are considered. Influence of structural and response parameters, such as stiffness, damping, acceleration and displacement thresholds, ground motion input, and uncertainties in structural modeling, are also investigated. The proposed approach can be considered as an alternative approach for describing the vulnerable behavior of nonstructural components that are sensitive to multiple parameters such as displacements and accelerations (e.g., partition walls, piping systems, etc.).     

KY-310B型牙轮钻机湿式除尘系统改进

文章阐述了KY-310B型牙轮钻机湿式除尘系统的构成及工作原理,针对其在使用过程中存在的问题,提出了改进方法,改进后,使用效果良好,对其他矿山同类钻机的高效使用具有借鉴作用。     

热力管道应力分析一般模式及所遇问题的解决

文章阐述了热力管道应力分析的重要性,提出了热力管道应力分析的一般模式以及对管道应力分析中可能遇到的问题进行了归纳,并对解决这些问题的方法进行了讨论。     

Live Load Distribution Formulas for Single-Span Prestressed Concrete Integral Abutment Bridge Girders

In this study, live load distribution formulas for the girders of single-span integral abutment bridges (IABs) are developed. For this purpose, two and three dimensional finite-element models (FEMs) of several IABs are built and analyzed. In the analyses, the effects of various superstructure properties such as span length, number of design lanes, prestressed concrete girder size, and spacing as well as slab thickness are considered. The results from the analyses of two and three dimensional FEMs are then used to calculate the live load distribution factors (LLDFs) for the girders of IABs as a function of the above mentioned parameters. The LLDFs for the girders are also calculated using the AASHTO formulas developed for simply supported bridges (SSBs). The comparison of the analyses results revealed that LLDFs for girder moments and exterior girder shear of IABs are generally smaller than those calculated for SSBs using AASHTO formulas especially for short spans. However, AASHTO LLDFs for interior girder shear are found to be in good agreement with those obtained for IABs. Consequently, direct live load distribution formulas and correction factors to the current AASHTO live load distribution equations are developed to estimate the girder live load moments and exterior girder live load shear for IABs with prestressed concrete girders. It is observed that the developed formulas yield a reasonably good estimate of live load effects in prestressed concrete IAB girders.     

工程总承包(EPC)项目风险的辨识及应对措施

文章阐述了EPC总承包的工作范畴以及风险特点,集中分析了决策阶段、投标报价、合同签订、设计阶段、采购阶段、施工管理阶段风险产生的原因,对主要风险的化解和规避提出了应对措施,并对风险控制和处理给出了建议。     

金属粉末气体雾化制备技术的研究现状与进展

依据气体雾化中喷嘴的结构特征,分析了国外几种具有工业实用价值的雾化技术的原理、性能与发展状况,评述了其优缺点和应用情况。