顺序阀控制引起参数摆动问题的探讨与研究

通过对机组按顺序阀控制时出现负荷、燃料等参数摆动问题的研究与分析,得出高负荷工况下3号高压调门参与调节并且当其开度处于其开度曲线的拐点处时参数波动将会被扩大,影响机组的安全运行。并提出相应的处理措施和建议,为其他电厂同类机组的安全运行和DCS厂家的设计提供依据和参考。     

基于阀位的主蒸汽流量计算可行性研究

对利用调门综合阀位计算主蒸汽流量需要解决的问题进行了分析,借助某汽轮机正规试验数据,建立了阀位与流量关系的数学模型,并对其相关性、重现性进行了检验。结果表明,当调门重叠度设置合理时,主蒸汽体积流量与综合阀位相关性较强;当调门系统未改变时,调门流量特性重现性较好;主蒸汽流量可由调门综合阀位和主蒸汽参数来求得,作为主蒸汽流量间接测量计算的又一方法,可用于日常离线分析计算。     

空调水系统变流量节能控制及实验研究

本文研究了阀位控制,设计了可实现变流量控制的实验平台。通过对阀位控制实验数据及其他控制理论结果的对比分析,认为该控制法具有节能性强的特点,易于推广。     

高参数大流量供热改造汽轮机中调阀调节抽汽研究

以某300MW亚临界机组高参数大流量供热改造为依托,对汽轮机中调阀调节抽汽进行研究。根据用户实际供热需求提供供热抽汽方案,核算机组叶片和轴向推力在供热工况下的安全性,研究并开发适用于热再调整抽汽的新型中压调节阀,制定热再抽汽控制逻辑。     

远程参数控制方法的摩托车道路模拟实验研究

通过实际道路试验,获得了摩托车车架关键部位的响应信号,经预处理并对测得信号进行了统计分析。利用美国MTS公司的道路模拟试验机和远程参数控制技术（RPC）模拟迭代出了接近实际响应的驱动信号,基本达到了在室内道路模拟机上直接模拟实际路况的要求。     

含紧连阀轴流式压缩系统的旋转失速控制

以经典Moore-Greitzer模型为基础,推导了含紧连阀的Moore-Greitzer三阶数学模型,并运用反推法构造旋转失速控制系统,对压缩系统旋转失速控制进行了仿真研究.结果表明:所设计的旋转失速控制系统能有效抑制压缩机旋转失速的发生,使压缩机在性能较高的区域稳定工作,保持较高的增压能力,扩大了压缩机的工作范围.     

机械增压器旁通阀控制方式与油耗及试验研究

本实验研究为基于最低燃油消耗率的旁通阀开度标定实验。其主要目的是将旁通阀由真空度自动控制改为电动调节,得出不同负荷下燃油消耗率随旁通阀开度的变化关系,从而找出同一负荷下最低油耗点及相应旁通阀开度,为旁通阀电子控制提供控制策略。试验表明优化后的旁通阀开度可以使发动机燃油消耗率较大幅度降低,在低速时,最大节油率4.02%;在高速时,最大节油率6.62%。而在中间转速时的最低燃油消耗率由原机的260.1g/kWh下降为257.3g/kWh,节油率为1.42%。而且优化旁通阀开度使得发动机在更大的转速范围内处于低油耗区域。而且旁通阀开度优化后,发动机在更大的负荷范围内处于低油耗区。这可以为制定电子控制旁通阀开启策略提供标定参考依据。     

基于背压和最佳阀位控制的滑压曲线实时优化及应用

针对目前凝汽器背压对滑压值的修正无普适算式可供遵循的问题,通过作图法推理获得了滑压设定值与凝汽器背压及机组负荷之间的二元函数表达式;利用流量变工况计算方法解决最佳综合阀位的确定问题,在满足机组日常运行需求的条件下达到汽轮机高压调阀节流损失最小化;将提出的基于凝汽器背压和机组负荷的二元函数滑压实时优化和基于流量变工况计算的最佳综合阀位控制滑压实时优化方法相结合,将凝汽器背压对滑压值的修正作为粗调,将最佳综合阀位控制对滑压值的修正作为细调,共同实现对滑压设定值的实时调整。在某660 MW超临界机组上的应用表明,该方法能够节约供电煤耗约1.12 g/(kW·h）。     

U型阀控制飞灰循环特性的试验研究

对循环流化床中的关键技术之一——Ｕ型非机械阀回料进行了实验研究，用所设计的Ｕ型阀对粒径很细（介于ＧｅｌｄａｒｔＡ和Ｂ类之间）的锅炉飞灰做回送试验，研究了阀内布风方式、风量及阀的输送段高度对固体循环量的影响。试验表明该Ｕ型阀具有良好的输送性能而且启动很快。     

卧式高压主汽阀碟与阀座间隙问题的分析与处理

文章针对现场装配过程中高压主汽调节阀阀碟与阀座存在间隙问题进行分析并提出处理方案,为以后处理或避免同类技术问题提供了借鉴和参考。     

锅炉排污热损失的分析与控制

锅炉排污量需要根据炉水水质条件和锅炉运行工况才能确定,否则就会造成较大的能量损失。     

电站锅炉的嵌入式监控系统设计

为了提高锅炉的自动监控水平,针对目前锅炉监控技术问题,提出了采用嵌入式微处理器为控制器核的锅炉状态参数监控设计方案,通过对监控系统的硬件和软件系统的设计,实现了对水位、烟气氧量、蒸汽流量、蒸汽压力、鼓风风量、炉膛温度等现场物理量的采集和处理,实现了锅炉的实时控制.     

中频电源在合理的逆变控制角下取样电路中电阻的计算

本文在分析KGPS100型可控硅中频电源逆变脉冲形成环节中的中频电压与电流取样电路中各有关量相互关系的基础上,推导出逆变控制角的数学表达式。在确定逆变起动电容容量的前提下,根据合理的逆变控制角,可直接计算出电流取样电阻的数值。从而可方便精确地确定出电流取样电阻可调臂的准确位置。为此型电源的安装、调试、运行、维修提供很大的方便。     

Experimental study of the stacking sequence effect on polymer/composite multi-layers submitted to thermomechanical cyclic loadings

Fast filling of hydrogen pressure tank leads to thermomechanical stresses in vessel structure. In this paper, the aim is to study the thermomechanical behaviour of the material used in the vessel structure. Flat coupons made of the same constituents as the hydrogen tank materials and with different stacking sequences have been tested under quasi-static tensile tests and fatigue. Three types of fatigue tests have been performed in order to understand damage mechanisms due to interactions between thermal and mechanical stresses: thermomechanical fatigue, 1 Hz mechanical fatigue and mechanical fatigue with a constant stress level stage. Damage development has been followed by acoustic emission and microscopic observations. Results show that, whatever the applied loading, there is a significant influence of the stacking sequence of the composite part. Moreover, the comparison of the material response to the different types of fatigue has revealed the harmful role of coupled temperature/mechanical cyclic stresses.     

The effects of improper refrigerant charge on the performance of a heat pump with an electronic expansion valve and capillary tube

For inverter heat pumps and multi-type heat pumps, conventional expansion devices such as capillary tubes, short tube orifices, and thermostatic expansion valves (TXVs) are being gradually replaced with electronic expansion valves (EEVs) because of the increasing focus on comfort and energy conservation. In this study, the effects of off-design refrigerant charge on the performance of a water-to-water heat pump are investigated by varying refrigerant charge amount from −20% to +20% of full charge in a steady state, cooling mode operation with expansion devices of capillary tube and EEV. The characteristics of the heat pump with an EEV are compared with those with a capillary tube. The capillary tube system is more sensitive to off-design charge as compared with the EEV system. Cooling capacity and COP of the EEV system show little dependence on refrigerant charge, while those are strongly dependent on outdoor conditions. In general, for a wide range of operating conditions the EEV system shows much higher performance as compared with the capillary tube system. The performance of the EEV system can be optimized by adjusting the EEV opening to maintain a constant superheat at all test conditions.     

JZ-7型空气制动机作用阀故障的原因分析与防止办法

针对我国铁路内燃、电力机车上使用的JZ-7型空气制动机中作用阀的作用与故障现象,进行了故障原因分析,并对防止作用阀发生故障提出了建议。     

Study on the high-pressure hydrogen gas flow characteristics of the needle valve with different spool shapes

The needle valve is a critical control unit for high-pressure hydrogen systems such as hydrogen refueling stations, which is the infrastructure of hydrogen energy. As an important part of the needle valve, the valve spool affects the flow characteristics of hydrogen in the valve and then affects the working performance and safety of the high-pressure hydrogen valve. In this paper, based on the real hydrogen gas model and the finite volume method, a CFD model of the high-pressure hydrogen needle valve is constructed to find out the influence of the valve spool shape on the performance and flow characteristics of the high-pressure hydrogen needle valve. The results show that high-pressure hydrogen will produce a sudden change in pressure around the valve spool and there will be a local high-speed area, and the turbulent intensity will also increase. The arc cone spool can increase the flow by 2%–8% at different openings of the valve, and reduce the maximum speed at the spool by 15% at small openings. In addition, the sudden change of pressure and the eddy current have also been improved. Flat-bottomed cone spool reduces turbulence intensity and energy consumption. Therefore, it can be concluded that changing the shape of the valve spool to have a larger flow area at a small opening can make the high-pressure hydrogen valve have a better flow field distribution. Flattening the cone angle of the spool can improve the turbulent flow in the valve. The research in this paper can provide research accumulation and theoretical support for the optimization design of the needle valve of the high-pressure hydrogen system.     

The effect of injection timing and intake valve close timing on performance and emissions of diesel PCCI engine with a full engine cycle CFD simulation

A full-cycle computational fluid dynamics (CFD) simulation coupled with detailed chemical kinetics mechanism has been used to investigate the effect of start of injection (SOI) timing and intake valve close (IVC) timing on performance and emissions of diesel premixed charge compression ignition (PCCI) engine. By sweeping SOI timing from −35 to −5 °CA ATDC and IVC timing from −140 to −80 °CA ATDC with fixed 50% exhaust gas recirculation (EGR) and 1.8 bar intake pressure, the contour plots for ignition timing, nitric oxides (NO_x), soot, hydrocarbon (HC), carbon monoxide (CO), indicated specific fuel consumption (ISFC), and ringing intensity have been developed. The results indicate that the operating range can be divided into kinetically controlled region and mixing-controlled region, in which the ignition timing is solely controlled by IVC timing and SOI timing respectively. To Minimize HC, CO, NO_x and soot emissions, SOI timing must be carefully adjusted within a limited range. With the retarded IVC timing, the operating range of SOI becomes wider for clean combustion. The IVC timing should be optimized with consideration of ignition timing and combustion efficiency at different SOI timing in order to improve fuel economy. For purpose of avoiding engine knock, the SOI timing around −20 °CA ATDC and early IVC timing are pursued.     

Effect of Placements （horizontal with vertical） on Gas-solid Flow and Particle Impact Erosion in Gate Valve

Gate valve has various placements in the practical usages.Due to the effect of gravity,particle trajectories and erosions are distinct between placements.Thus in this study,gas-solid flow properties and erosion in gate valve for horizontal placement and vertical placement are discussed and compared by using Euler-Lagrange simulation method.The structure of a gate valve and a simplified structure are investigated.The simulation procedure is validated in our published paper by comparing with the experiment data of a pipe and an elbow.The results show that for all investigated open degrees and Stokes numbers(St),there are little difference of gas flow properties and flow coefficients between two placements.It is also found that the trajectories of particles for two placements are mostly identical when St 1,making the erosion independent of placement.With the increase of St,the distinction of trajectories between placements becomes more obvious,leading to an increasing difference of the erosion distributions.Besides,the total erosion ratio of surface T for horizontal placement is two orders of magnitudes larger than that for vertical placement when the particle diameter is 250 μm.     

用单片机数字调节器实现调节阀智能化

对传统调节阀原理特性及其使用中存在问题进行了分析,采用伺服放大器功能软件化的思想,得出一种利用系统参数辩识方法求取阀门工作流量特性,并利用该特性实现调节阀智能化的方案。对该方案的硬件实现及软件功能进行了介绍。