北方地区垃圾焚烧发电项目直接空冷系统探讨

阐述垃圾焚烧发电项目采用直接空冷的必要性和优势,分析了自然环境(海边风)对直接空冷系统的影响,提出了解决措施,探讨直接空冷机组排汽接管和凝结水箱合二为一排汽装置,为类似工程提供参考。     

汽轮机调节汽阀阀碟螺栓故障分析与研究

针对工业汽轮机调节汽阀故障,导致汽轮机停机的问题,对工业汽轮机调节汽阀的结构特点进行了分析研究,对调节汽阀阀碟螺栓断裂和磨损,导致阀碟脱落问题的故障机理及工作环境进行了深入分析研究,提出了减少阀碟螺栓长度、对阀碟螺栓跳档使用及改进阀碟的装配工艺等措施,利用三维软件对其进行建模并利用ANSYS软件对改进前和改进后的阀碟螺栓进行了应力分析。研究结果表明,该方案可以减小阀碟螺栓承受的交变应力,提高阀碟螺栓根部的强度,可以改进因热胀不均而导致螺纹副出现相对位移的情况。结合宁夏石化机组的实际故障案例,通过将该方案应用于该机组中,彻底解决了该机组因阀碟螺栓断裂而导致机组故障问题。     

国产超临界1000 MW汽轮机组主汽阀结构优化分析

对国外引进的主汽阀结构进行强度分析,发现该主汽阀结构不能满足强度要求,文中对该主汽阀进行结构优化,应用有限元方法计算分析了国产超临界1000 MW汽轮机组主汽阀力学特性,提出优化方案,并与原设计方案进行了对比分析,结果发现优化后的主汽阀结构可以满足许用要求。     

空负荷运行时汽轮机调节系统的缺陷分析和处理

通过分析空负荷运行时汽轮机调节系统存在的调节系统整定不当、调节汽阀阀座升起、油动机或者调节汽阀卡涩、调节汽阀关闭不严等缺陷现象及其产生原因,针对性提出解决办法和注意事项,以维持汽轮机调节系统的良好。     

空、湿冷机组冷端联合优化对经济性的影响

电厂汽轮机冷端空、湿冷联合优化改造,是目前汽轮机冷端较好的一种改造方式,利用空冷机组的排汽来加热湿冷机组的凝结水,既减少了空冷机组排汽的热量损失,同时又提高了湿冷机组的凝结水温度,提高了机组的经济性。     

改进型A152(z)主汽阀阀壳热应力实测及分析

为了提高国产300MW机组的使用寿命,该机组自第13台起改用主汽阀启动,以降低高温部件的热应力,使得高温部件的寿命得到保证。本文详细介绍了主汽阀阀壳热应变测试方法及高温电测技术。试验得到的主汽阀阀壳应力值将为计算和结构改型提供一定依据。     

低压轴承标高变化对600MW空冷机组轴系动特性影响研究

根据轴承负荷敏感性分析结果,研究600MW空冷机组敏感轴承对其它落地轴承及整个轴系的影响。考虑低压缸双排汽的特点,分析了3#、4#轴承在不同标高变化状态下的各轴承负荷的变化情况,研究了轴系临界转速的变化规律。结合空冷机组排汽参数的频繁变化,分析了轴颈不平衡响应特性。进而根据轴系振动特征,通过对数衰减率研究机组的稳定性问题。     

百万核电汽轮机主汽调节联合阀壳体设计

为了保证百万核电主汽调节联合阀在实际应用中能高效、安全可靠地运行,在主汽调节联合阀壳体的设计中,针对主汽调节联合阀壳体的结构,包括进出口锥体结构的设计,阀壳壁厚的计算设计以及壳体应力分析和材料选取等方面进行了详细的计算和验证。     

轴向排汽凝汽器支座载荷分析

轴向排汽凝汽器具有流动损失少,结构紧凑、拆装方便等优点,在大型电站汽轮机中具有良好的应用前景。针对轴向凝汽器的轴向载荷引起各支座载荷的影响,结合漕泾项目轴向排汽凝汽器结构特点,通过等效密度方法建立了凝汽器简化模型,计算分析了净重、运行及满水工况下凝汽器各支座载荷,并于设计参数进行了对比。结果表明轴向排汽凝汽器的支座载荷受到运行工况的影响明显,在轴向排汽凝汽器结构设计中需要考虑轴向载荷引起的支座载荷变化。     

空排止回阀旁路控制部分设计

介绍了空排止回阀的用途、结构特点及原理。并以公称压力20MPa，公称通径175mm的空排止回阀为例，简述了旁通节流部分的设计与计算。     

大型空间离轴三反相机分体支撑结构设计

针对某1m分辨率、200 km幅宽的大尺度空间相机框架支撑结构轻质量、高刚度的设计要求,设计了一种轻型分体支撑结构.首先从大型空间离轴三反相机研制需求出发,综合比刚度、热稳定性及加工工艺等因素选择了性能良好的高体份SiCp/Al复合材料;然后以结构质量分数为约束条件,建立以基频为目标函数的拓扑优化数学模型,得到了拓扑结...     

21世纪初中国重大工程建设中的若干机械强度问题

就与结构安全性可靠性有关的近期重大建设工程和近二十年来国内外发生的由于结构强度和振动问题引发的重大事故进行综述。提出重大建设工程中的若干机械强度与振动问题。这些工程项目是喷气式民航飞机、长寿命高可靠性通信卫星、100万千瓦核电站、提速铁路、磁悬浮铁路、西气东输工程和巨型水电站。最后讨论应予考虑的几个问题。     

基于压电陶瓷驱动的腹腔手术微型机器人

介绍了一个基于压电陶瓷驱动的多节蛇型游动腹腔手术微型机器人,其特点是响应速度快,运动精度高,作用力与动作范围大,每一节均可实现两个自由度方向上±60°范围内迅捷而灵活的动作.对设计中的两个     

Tribological characteristics of (TiZrHfVNbTa)N coatings applied using the vacuum arc deposition method

The effect of the pressure of the nitrogen atmosphere during the formation of vacuum arc nitride coatings based on high entropy alloys of the Ti-Zr-Hf-V-Nb-Ta system on their structure, hardness, and tribotechnical characteristics is considered. It is shown that strong nitride-forming components lead to the dependence of the structural state and properties on the pressure of the nitrogen atmosphere during coating deposition. Deposition at a nitrogen pressure of 0.4 Pa results in the formation of a texture with the [111] axis when the applied bias potential is ?70 V and when the bias potential is equal to ?150 V the textural structure is biaxial ([111] and [110]) textures and high value of hardness of 51 GPa Along with that the highest value of wear resistance (under oxidizing-mechanical wear) is inherent to coatings formed under the pressure of nitrogen of 0.09 Pa. The strongest microdeformation of coating crystallites corresponds to this pressure.     

A simply constructed but efficacious shock tester for high-g level shock simulation

A simply constructed shock tester, different from existing drop table machines, is developed for high-g level shock environment simulation. The theoretical model, structure design, and working principle of the drop tester are described. A prototype device is set up, where a carbon fiber reinforced polymer with a high specific modulus is used. Using a Bru?el & Kj?r high-g accelerometer, experiments to verify the validity of the design are carried out and results are given. The maximum acceleration level is in excess of 60 000 g, limited only by the manual driving force.     

模具钢、复合陶瓷强化模具钢和结构陶瓷高温摩擦学性能比较

从实用角度出发，模拟金属挤压工况，对比研究了模具钢、陶瓷薄膜强化模具钢和结构陶瓷三种模具材料的摩擦学特性，测试了高温下的磨损规律。研究结果对挤压模具设计具有指导意义。     

Transmission electron microscopy studies of microstructure of Ti–Nb and Ti–Ta alloys after ball milling and hot consolidation

Two Ti alloys with compositions Ti?10Ta and Ti?10Nb (at.%) were milled in a high‐energy mill for a maximum of 80 h in an argon atmosphere. A nanocrystalline structure of α‐Ti(X) (X = Ta or Nb) solid solution was formed in both investigated alloys after milling, as shown by X‐ray diffraction. Transmission electron microscopy observations of powders milled for 80 h revealed chemical inhomogeneity of particles in nanometre‐scale regions and an average crystallite size of about 10 nm. The pulse plasma sintering method was applied for hot consolidation of milled powders. The mean density of pulse plasma sintering compacts of Ti–Nb alloy was about 99.5% of the theoretical value, whereas the density of the Ti?10Ta sample was lower, close to 92% of the theoretical value. Transmission electron microscopy observation of compacted samples showed that the sintering process caused the formation of a two‐phase α + β structure in both investigated alloys, with a mean grain size of 220 nm. The chemical inhomogeneity and high degree of deformation in nanometre‐scale regions of milled powders led to a martensitic transformation, resulting in formation of a 9R martensite structure.     

Tribo-oxidation of Self-mated Ti3SiC2 at Elevated Temperatures and Low Speed

The tribological behavior of self-mated Ti₃SiC₂ is investigated from ambient temperature to 800?°C at a sliding speed of 0.01?m/s in air. The results show that at the temperatures lower than 300?°C, friction coefficient and wear rates are as high as 0.95 and 10^?3?mm³/N?m, respectively. With the temperature increasing to 600?°C, both the friction coefficient and wear rates show consecutive decrease. At 700 and 800?°C, friction coefficient and wear rates are 0.5 and 10^?6 mm³/N?m, respectively. According to the wear mechanism, the tribological behavior of Ti₃SiC₂ can be divided into three regimes: mechanical wear-dominated regime from ambient temperature to 300?°C characterized by pullout of grains; mixed wear regime (mechanical wear and oxidation wear) from 400 to 600?°C; and tribo-oxidation-dominated wear regime above 700?°C. The tribo-oxides on the worn surfaces involve oxides of Si and Ti. And, species transformation occurs to these two oxides with the increasing temperature. In the competition oxidation of elements Ti and Si, Si is preferably oxidized because of its high active position in the crystal structure. Additionally, plastic flow is another notable characteristic for the tribological behavior of self-mated Ti₃SiC₂.     

基于ZigBee无线网络的分户热计量系统设计

现有的集中热水采暖分户热计量系统,存在投资大,安装维护成本高而且收费不合理,热能浪费等问题,针对这些问题,提出了基于ZigBee无线传感器网络的分户热计量系统的设计与实现方法。构建了基于ZigBee的无线监测实时采集系统,给出了网络节点的硬件和软件的详细设计方案,并提出对热费计量的计算方法。该系统结构简单,投资小,安装维护成本低,可在分户热计量领域中推广和运作,具有很大的发展前景。     

Response Sensitivity to Design Parameters of RV Reducer

Dynamic characteristic significantly a ects performance of RV reducer. The current researches mainly pay attention to free vibration properties of RV reducer. In order to satisfy the increasing demand on high performance,response sensi?tivity is analytically studied on the basis of cyclic symmetry structure. Based on the structure characteristics,a dynamic model is developed by taking into account the influence of bearing sti ness,crankshaft bending sti ness and mesh sti ness within planetary and cycloidal stages. For the model,governing equation of motion is derived and solved by Fourier series method. The solution revealed that forced vibrations at primary frequency are well defined structural. There exist three typical forced vibration modes: rotational,translational and planetary component modes. Response sensitivity to basic design parameters is obtained as closed?form expressions by di erential method. With the typical vibration modes,response sensitivity is simplified and classified into three types. Calculation of sensitivity implies that vibrations of the output wheel are sensitive to eccentricity. As eccentricity increases,sensitivity of translation decreases first and then increases,but sensitivity of rotation always increases. The proposed method for analyzing response sensi?tivity provides some principles for selecting parameters for RV reducer from the point of view of forced vibration.