锅炉汽包疲劳寿命管理系统的研究

介绍了锅炉汽包疲劳寿命管理系统的结构,软件特性及功能,运行情况表明,该管理系统可实时指导锅炉启动,提高锅炉启动的安全性与经济性,运用该系统,可提高电厂的生产和管理水平。     

山区公路长下坡路段货车鼓式制动器温升规律数值分析

结合龙岩典型长下坡事故黑点路段,建立鼓式制动器温升规律有限元热分析模型,对货车鼓式制动器在紧急和持续制动工况下的温升规律和具体路段下重复制动货车鼓式制动器的温升规律进行了深入分析,并进行了实车试验验证.研究结果表明:车辆载重、车辆运行速度、道路坡度、制动鼓比热容是影响制动鼓温升规律的主要因素;实车制动行为与驾驶员心理、车辆运行速度及道路线形条件有密切关系,只有结合具体路段车辆运行状况及制动方式才能相对准确地进行模拟分析实际制动鼓的温升规律;基于运行速度的长下坡路段制动鼓重复制动温升规律模拟是一种可参考使用的方法.     

Prediction of segregation characterization based on granular velocity and concentration in rotating drum

In a binary granular system composed of two types of particles with different granule sizes and the same density, particle sorting occurs easily during the flow process. The segregation pattern structure is mainly affected by the granular velocity and granular concentration in the flow layer. This paper reports on the experimental velocity and concentration measurement results for spherical particles in a quasi-two-dimensional rotating drum. The relationship between the granular velocity along the depth direction of the flow layer and granular concentration was established to characterize structures with different degrees of segregation. The corresponding relationships between the granular velocity and concentration and the segregation pattern were further analyzed to improve the theoretical models of segregation (convection–diffusion model and continuous flow model) and provide a reference for granular segregation control in the production process.     

Effect of drum structure on particle mixing behavior based on DEM method

The optimization of the drum structure is beneficial to improve the particle motion and mixing in rotary drums. In this work, two kinds of drum structures, Lacy cylinder drum (LC) and Lacy-lifters cylinder drum (LLC), are developed on the basic of cylinder drum to enhance the heat transfer area. The particle motion and mixing process are simulated by DEM method. Based on the grid independence and model validation, the contact number between particles and wall, particle velocity profile, thickness of active layer, particle exchange coefficient, particle concentration profile and mixing index are demonstrated. The influences of the drum structure and the operation parameters are further evaluated. The results show that the contact number between particles and wall is improved in LC and LLC compared to cylinder drum. The particle velocity in LC is higher than that in cylinder drum at high rotating speed, and the particle velocity of the particle falling region is significantly improved in LLC. Compared to cylinder drum and LC, the thickness of active layer in LLC is smaller, while the local particle mixing quality is proved to be the best in the active region. In addition, the particle exchange coefficients between static region and active region in the three drums are compared and LLC is found tending to weaken the particle flow. Besides, the fluctuations of particle concentration in the active region, static region, and boundary region are weakened in LLC, and the equilibrium state is reached earlier. In addition, the overall particle mixing performance in cylinder drum, LC and LLC is analyzed. The particle mixing performance in cylinder drum is the worst, while the difference in mixing quality of LC and LLC depends on the operation conditions.     

无圆周相对滑动拉丝卷筒结构的设计

分析了现有拉丝卷筒产生相对滑动的原因,认为是卷筒过度圆弧面导致圆周相对滑动,而圆周相对滑动是造成金属线材表面划伤、斑纹等缺陷的主要原因.设计了无圆周相对滑动的拉丝卷筒结构,取消了卷筒过度圆弧面,用推升滑轮实现卷筒上的线材上移.改进后的拉丝卷筒可以消除圆周相对滑动,减少了因相对滑动给线材表面带来的缺陷.     

纺织卷绕筒丝线长度测量系统设计

介绍一种直接在线测量卷绕辊丝线长度的方法,首先建立了圆锥卷绕丝线动态数学模型,然后对工作过程和数学模型解态进行分析,通过测量卷绕机梭子摆动次数和卷绕转速间接算出缠线的长度。实际测量数据表明,该方法测量精度优于传统方法,稳定性好,一致性强。     

采煤机滚筒调高截割记忆程控的控制策略

针对采煤机滚筒调高机构的特点,即定量、开关式控制液压系统,分析了记忆程控——预知控制结果的再现控制的特征。给出了滚筒调控静态数学模型,并根据调高机构的调控特征方程与采样点间顶底板变化特征方程的差异,给出了在其采样区间内的指令式控制策略,其方法的规则条目少、简单易运算、符合实际控制要求。     

鼓式制动器稳定性的复模态分析

针对鼓式制动器出现的制动噪声问题,根据复模态分析基本原理建立有限元模型,对制动噪声进行预测.全面分析制动压强、制动鼓角速度、摩擦系数、杨氏模量、摩擦衬片厚度等因素对制动稳定性的影响.影响因素分析结果表明:摩擦衬片杨氏模量对制动噪声有影响显著;制动压强、摩擦系数和制动鼓杨氏模量对制动噪声影响较大;摩擦衬片厚度和制动蹄杨氏模量对制动噪声具有一定影响;制动鼓角速度对制动噪声影响很小.     

多次紧急制动工况下的鼓式制动器热-结构耦合分析

针对汽车鼓式制动器在制动过程中的开裂失效问题,基于运动学、动力学、摩擦学与热-结构耦合的综合分析技术及实验技术,建立了三维瞬态热-结构耦合理论模型及有限元模型;分析多次紧急制动工况下制动鼓温度场和应力场在径向、周向、轴向的分布特征,得到了结构场与温度场的耦合作用结果 ;分析了温度、应力应变、压力三者间的相互耦合作用规律.结果表明:制动鼓的开裂失效主要处于温升大的区域,是由热应力引起的热疲劳失效,且由于周向压应力比径向和轴向压应力大,从而导致制动鼓的裂纹方向均为沿轴向伸展.     

甲醇合成中汽包水位三冲量控制的改进

为了有效克服虚假水位现象,提高对汽包液位的控制能力,根据甲醇生产的工艺特点,分析不同的水位控制方式,提出汽包水位三冲量控制方案并加以改进.对水位信号采用冗余测量提高控制精度,对给水流量和蒸汽流量通过延迟滤波提高系统稳定性,采用ABB IndustrialIT分散控制系统实现控制过程.控制方案稳定,可以保持给水和蒸汽平衡,有效克服虚假水位现象,保证汽包液位在允许范围内.