超低排放燃煤电厂SO3和可凝结颗粒物迁移规律研究

为获得燃煤电厂SO3和可凝结颗粒物（CPM）的迁移排放特性,对国内多家超低排放燃煤机组烟气中SO3和CPM进行现场测试。结果表明:有4家电厂的选择性催化还原（SCR）脱硝系统对SO3总生成量的贡献率在42.01%~52.08%之间,湿法烟气脱硫装置（WFGD）对SO3的脱除效率在51.20%~65.20%之间,湿式电除尘器（WESP）对SO3的脱除效率在77.25%~79.27%之间;从排放烟气看,配备WESP的超低排放改造电厂均能有效脱除SO3,总脱除效率达到94.28%以上;此外,现有污染物控制装置对CPM有一定脱除作用,其中,WFGD对CPM的脱除效率在34.64%~47.20%之间,WESP对CPM的脱除效率在36.20%~39.26%之间;CPM主要由SO42–、Cl–和NO3–等酸根离子组成,CPM无机成分中的NH4+和SO42–分别来自烟气中的NH3和SO3,其质量浓度与烟气中NH3和SO3的质量浓度正相关。     

基于Ziegler-Nichols优化算法的火电机组负荷频率PID控制研究

随着风电和光伏接入电网的规模不断扩大,电网负荷峰谷差逐渐增加,电网的频率控制出现超调量过大、调节速度过慢等一系列问题。本文针对互联电力系统的负荷分配以及频率控制问题,提出考虑发电机组分配系数的互联电力系统负荷频率控制方法。首先,建立单个区域包含多个火电机组的两区域电网自动发电控制（AGC）系统仿真模型,根据各发电机组的煤耗特性建立经济性目标函数,并且获得最优的出力分配系数;然后,基于联络线功率和频率偏差控制（TBC-TBC）的控制模式,采用经Ziegler-Nichols相关算法优化后的PID控制,并对优化后PID控制器的鲁棒性进行分析研究;最后,基于两区域系统仿真模型,在一定的负荷扰动工况下进行仿真验证。仿真结果表明:该分配方法能够有效节省煤耗,本文算法优化后的PID控制器在频率恢复速度方面具有一定的优势,并且鲁棒性良好。     

生物质两段式富氧气化-燃气轮机燃烧集成发电系统模拟研究

为实现生物质能量的高效清洁利用，本研究基于两段式富氧气化系统改进燃气品质，并将获得的洁净高热值可燃气用于燃气轮机燃烧。通过Aspen Plus模拟研究分析了氧体积分数、气化温度对气化特性、燃机运行特性的影响，研究结果证实了生物质气化燃气在燃气轮机应用的可行性，并发现氧体积分数提高对改善生物质气化燃气品质及系统发电效率具有重要意义。两段式气化二次气化温度提高会引起气化效率及系统发电效率下降，因此气化温度需控制在合适范围。在满足生物质灰分完全熔融液化分离的前提下，气化温度可取较低值；两段式气化系统可选择氧体积分数为50%~60%时较佳。在氧体积分数60%、气化温度1 200 ℃时，生物质气化-燃气轮机集成发电系统发电效率（η_t）达最优，为34%，此时生物质可燃气低位热值（Q_LHV）为9.54 MJ/m³，两段式气化效率（η_CGE）为78.65%。     

Microstructures and mechanical properties of creep resistant steel for application at elevated temperatures

The subject of this paper is the microstructural and mechanical characterisation of regions of the heat-affected zone (HAZ) in steels containing 9–12% Cr that are used for operation at elevated temperatures. Tests were performed on regions in the HAZ, which was created by physical simulation using a thermal welding simulator. Half of the simulated samples (SSs) were tested at room temperature (RT) and at an operating temperature (OT) of 600 °C immediately after simulation/welding, while the rest of the simulated samples were tested at RT and at the OT after heat treatment following the welding, i.e., post-weld heat treatment (PWHT). In addition to the results from mechanical testing, the results from microstructural analysis using light microscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) are also presented. The manner in which PWHT contributes to the creep resistance of the HAZ in P91 steel is demonstrated.     

Experimental investigation of high-temperature corrosion properties in simulated reducing-sulphidizing atmospheres of the waterwall fireside in the boiler

The presence of reducing atmospheres of the waterwall fireside in the boiler due to extensive use of low-NOx combustion mode caused severe high-temperature corrosion problems. In this study, high-temperature sulphur corrosion properties of two types of low alloyed waterwall steel (15CrMoG and 12Cr1MoVG) in two kinds of reducing-sulphidizing atmospheres were investigated by lab-scale experiments. The experimental atmospheres and temperature were simulated according to field measurements in the boiler of a thermal power plant. The experimental results showed that the reducing-sulphidizing atmosphere with CO was more corrosive, and the CO accelerated the corrosion of H₂S and worsened the corrosion. The CO inhibited the formation of oxide scales, provided some corrosion resistance, and produced the intensely corrosive COS. The corrosivity of the alkali metal chlorides was limited in the reducing-sulphidizing atmosphere without CO, while the corrosion was strongly hindered in the reducing-sulphidizing atmosphere with CO.     

超超临界锅炉水冷壁T23/12Cr1MoV异种钢焊接接头焊后热处理裂纹分析

分析了T23/12Cr1MoV异种钢焊接接头焊后热处理裂纹的宏观和微观特征、断口形貌及接头的显微组织,测试了接头的硬度分布,在此基础上讨论了裂纹的性质及形成原因,并提出了防止裂纹的措施。结果表明,裂纹启裂于T23钢侧焊趾部位,沿粗晶粒热影响区(CGHAZ)晶界扩展,为典型的再热裂纹。焊后热处理明显降低了异种钢焊接接头两侧热影响区的硬度,T23钢侧CGHAZ产生再热裂纹与其在焊后热处理过程中晶界析出碳化物有关,其析出促进了孔洞的形成。在焊后热处理前,对异种钢焊接接头进行一次550 ℃×1 h的中间热处理有利于抑制再热裂纹的产生。     

基于用户可中断负荷的实时负荷控制决策技术应用

当特高压直流严重故障时电网会采取紧急切负荷措施,为了实现切负荷时的精准,本文提出了基于用户可中断负荷的实时负荷控制决策技术,研究了控制决策过程中涉及的快速响应、精准控制、稳控保障等关键技术,设计了用户动态序位表、决策准备、负荷循环补备、失效开关清单等决策中使用的机制,最后模拟了实时控制决策的应用场景。本文提出的实时负荷控制决策技术已经在江苏电网大规模源网荷友好互动系统中应用,实现了在接收切负荷指令后对用户可中断负荷实时精准控制。     

Influence of oil on R-410A two-phase frictional pressure drop in a small U-type wavy tube

This study presents single-phase and two-phase pressure drop data with oil concentration C = 0, 1, 3 and 5% in a copper wavy tube having an inner diameter of 3.25 mm and a curvature radius of 6.35 mm. The ratio of frictional factor between U-bend in wavy tube and straight tube (f_C/f_S) is about 1.5 to 2.5 for Re = 2500 ∼ 25000. The effect of secondary flow is very crucial in the U-bend that it increases the pressure drop considerably. However, the effect of oil concentration on friction factor is negligible provided the properties are based on mixture. The ratio between two-phase pressure gradients of U-bend and straight tube is about 3. This ratio is increased with oil concentration and vapor quality. The oil effect on two-phase pressure drop is especially pronounced at high vapor quality because the effective oil concentration in liquid mixture is increased with vapor quality. The frictional two-phase multiplier for straight tube can be fairly correlated by using the Chisholm correlation. A modified two-phase friction factor based on the Geary correlation is also utilized to predict the frictional two-phase pressure gradient in U-bend. The predictions give a good agreement to the present oil–refrigerant data with a mean deviation of 12.92%.     

全工况下的1000MW超超临界机组协调控制系统多模型广义预测控制方法及其工程应用

为优化1 000 MW超超临界机组协调系统控制性能,设计了基于多模型广义预测控制算法的新协调控制方法。为避免机理建模与实际情况的偏差,利用现场试验数据建立全工况的传递函数模型集,以逼近被控对象的非线性过程。新协调控制策略以多模型为基础,结合被控对象动态特性,并保留了"反馈+前馈"的控制结构。工程应用表明,多模型广义预测控制方法与传统的PID控制相比,提升了机组协调控制系统性能,同时明显改善了自动发电控制(automatic generation control,AGC)的运行考核结果。     

Effects of thermodynamics parameters on mass transfer of volatile pollutants at air-water interface

A transient three-dimensional coupling model based on the compressible volume of fluid(VOF) method was developed to simulate the transport of volatile pollutants at the air-water interface. VOF is a numerical technique for locating and tracking the free surface of water flow.The relationships between Henry's constant, thermodynamics parameters, and the enlarged topological index were proposed for nonstandard conditions. A series of experiments and numerical simulations were performed to study the transport of benzene and carbinol. The simulation results agreed with the experimental results. Temperature had no effect on mass transfer of pollutants with low transfer free energy and high Henry's constant. The temporal and spatial distribution of pollutants with high transfer free energy and low Henry's constant was affected by temperature. The total enthalpy and total transfer free energy increased significantly with temperature, with significant fluctuations at low temperatures. The total enthalpy and total transfer free energy increased steadily without fluctuation at high temperatures.