基于语句表和Profibus的水箱液位与进水口流量串级控制系统

提出一种基于语句表和Profibus的水箱液位与进水口流量串级控制方案。给出系统组成和设备硬件组态,说明使用符号地址访问数据块中数据的方法。阐述了PID功能块FB41的使用方法和主要参数说明,给出了语句表主要程序段。相关测试结果表明:该系统响应速度快,超调量小。     

Dynamic delayed detached eddy simulation of a multi‐inlet vortex reactor

The multi‐inlet vortex reactor (MIVR) is used for flash nanoprecipitation to manufacture functional nanoparticles. A validated computational fluid dynamics model is needed for the design, scale‐up, and optimization of the MIVR. Unfortunately, available Reynolds‐averaged Navier‐Stokes methods are unable to accurately model the highly swirling flow in the MIVR. Large‐eddy simulations (LES) are also problematic, as excessively fine grids are required to accurately model this flow. These dilemmas led to the application of the dynamic delayed detached eddy simulation (DDES) method to the MIVR. In the dynamic DDES model, the eddy viscosity has a form similar to the Smagorinsky sub‐grid viscosity in LES, which allows the implementation of a dynamic procedure to determine its model coefficient. Simulation results using the dynamic DDES model are found to match well with experimental data in terms of mean velocity and turbulence intensity, suggesting that the dynamic DDES model is a good option for modeling the turbulent swirling flow in the MIVR. © 2016 American Institute of Chemical Engineers AIChE J, 62: 2570–2578, 2016     

液体中气泡生成影响因素的试验研究

为了提高浆态床反应器内的气含率,提高反应速率,利用高速摄影技术,研究了气泡在液体中形成的特性,在不同气孔内径、不同气体流量下分别考察了平面孔、内伸孔2种进气方式对气泡在水中生成的影响,测算了气泡脱离时的大小及生成所用时间;并考察了内伸孔高度、水温对气泡生成的影响。结果表明:相同试验条件下,生成气泡大小分别随着气孔内径、气体流量的增大而增大,内伸孔进气生成的气泡体积小,用时短,且与内伸孔的内伸高度有关;高温水中气泡生成用时较短,体积较小。     

城市隧道竖井送排式通风优化

为了更有效地发挥送排风竖井在城市隧道中的通风作用,选择合理的送排风组合是一个重要的途径。本文采用CFD方法,对5种排风速度与5种送风速度的25种送排风组合进行了模拟,分析了不同送排风组合隧道内的通风效果。模拟结果表明:当送排比大于1时,隧道内会出现回流,且送排比越大,隧道回流效应越强,经济效益越低。隧道内气流分布和污染物浓度都与送排风组合有关,较大的排风速度虽有利于降低污染物浓度,但能耗也较大,过大或者过小的送风速度都会使隧道局部污染物浓度过高,降低通风作用。因此,综合考虑隧道通风经济性和实用性,确定排风速度为5~6m/s和送风速为8~12m/s为最优组合。选择合理的送排风组合,不仅能有效控制隧道污染物浓度,还能减少能量损失,对城市隧道的建设具有指导意义。     

脱硫用水力旋流器进口压力与浓度对其性能影响的研究

本实验研究了水力旋流器的进口压力与浓度对旋流器性能的影响,包括生产能力、分级效率、分级精度、分级粒度等指标。对于不同的浓度和进口压力对旋流器性能的影响做了定性的分析,研究其变化规律有助于水利旋流器的进一步优化和改进。     

基于CO2稀释的旋流无焰燃烧理论判别方法

基于温度判据和时间判据,本文建立了考虑旋流入口条件和CO₂稀释的无焰燃烧理论判别方法并进行验证,进而讨论了结构参数和操作参数对燃烧模式和火焰稳定性的影响。模型预测的旋流无焰燃烧临界氧浓度与文献中实验数据相比,最大相对误差不超过8%。降低氧浓度、减小当量比或提高入口流量时,温度判据1变化不大,而时间判据更易满足,因此有利于实现无焰燃烧;低旋流数条件下,无焰燃烧稳定性较差。增大燃烧室高度时,温度判据1更易满足,而时间判据更难满足,温度判据1分界线下移更快,有利于形成无焰燃烧;减小燃烧室截面积时,温度判据1变化不大,而时间判据更易满足,有利于实现无焰燃烧;增大燃烧器出口面积时,温度判据1和时间判据均更难满足,且时间判据分界线下移更快,不利于形成无焰燃烧。     

切流式三旋单管内固相颗粒运动规律的数值研究

采用商用软件Fluent 6.3,利用随机轨道模型对切流式三旋单管内固相颗粒运动轨迹进行了数值模拟,结果表明颗粒运动轨迹随机性较大,对气流的跟随性较好,受湍流脉动的影响较大。颗粒在单管内的逃逸与捕集运动规律的统计结果表明:不大于5μm的颗粒主要在排气管底部和分离筒体发生逃逸,随着粒径的增加,颗粒的分离效率增加,在排气管底部和分离筒体上部逃逸比重增加,而在分离筒体中底部颗粒的逃逸比重减少。总结来说,排气管短路流、分离筒体内旋流夹带逃逸是影响切流式三旋分离性能的主要原因,可以从这些方面进行三旋分离性能的优化与改进。     

Optimized centre-feed clarifier design for the Tai Po Sewage Treatment Works,Hong Kong

Stability of sludge blanket is a critical factor controlling the performance of clarifiers. A three-dimensional computational fluid dynamics (CFD) model was applied to optimize the clarifier design at the Tai Po Sewage Treatment Works, Hong Kong. Validated by field data, the CFD model evaluated the key clarifier design elements including side-water depth, centre-feed inlet, flocculation well and returned activated sludge (RAS) flow. Based on field observations and modelling results, the new design aims at eliminating the strong turbulence typical of centre-feed inlets in the clarifier, thus creating a better flocculation environment, and reducing disturbance to the sludge blanket. The modelling results also demonstrated a marked improvement in clarifier performance after the increase in clarifier depth and hence sludge storage capacity. The increased storage capacity reduces the risk of high sludge blanket levels upsetting the clarified effluent quality under high flow or solids loading conditions.     

The effect of elevated inlet air temperature and relative humidity on cogeneration system

The effect of elevated inlet air temperature and relative humidity on a gas turbine (GT) cogeneration system performance was investigated. The analysis was carried out on a GT of a capacity 171 MW at ISO condition, which is integrated with a dual pressure heat recovery steam generator (HRSG), the cogeneration system had been tested under Kuwait summer climate conditions. A computational model was developed and solved using engineering equation solver professional package to investigate the performance of a dual pressure GT‐HRSG system. The suggested HRSG is capable of producing high‐pressure superheated steam at 150 bar and 510°C to operate a power generation steam turbine cycle, and a medium pressure saturated steam at 15 bar to run a thermal vapor compression (TVC) desalination system. In this research, the influence of elevated inlet air temperature and relative humidity on the energy assessment of the suggested cogeneration system was thoroughly investigated. Results indicated that operating GT under elevated values of inlet air temperatures is characterized by low values of net power and thermal efficiency. At elevated inlet air temperatures, increasing relative humidity has a small positive impact on GT cycle net power and thermal efficiency. Integrating the GT with HRSG to generate steam for power generation and process heat tends to increase energy utilization factor of the system at elevated inlet air temperatures. Increasing inlet air temperature plays a negative impact on power to heat ratio (PHR), while relative humidity has no effect on PHR. Copyright © 2009 John Wiley & Sons, Ltd.     

导叶不同步装置降低蜗壳进口压力的机理研究

利用基于特征线原理的蜗壳进口压力的表达式，结合含导叶不同步装置的水泵水轮机的全特性曲线，对高水头抽水蓄能电站中，低比转速水泵水轮机甩负荷时，导叶不同步装置降低蜗壳进口压力的机理进行了理论分析和探讨。导叶不同步装置的及时投入，增大了流量特性曲线在“S”特性影响区内的正斜率，减小了水轮机甩负荷时每一时间步长内的蜗壳进口压力的上升幅值，从而在一定程度上降低了蜗壳进口压力的最大值，但并不改变蜗壳进口压力的双峰特性。另外，在水轮机甩负荷工况的同时，MGV装置的延时投入时间越短，预开启导叶的附加开度的增加速率越快，蜗壳进口压力的最大值就降低的越多。