大功率晶闸管和硅整流管元件试验台的研制

针对机车大功率晶闸管和硅整流管元件的检测要求，研制了用于测试其特性的自动检测试验台，并且详细阐述了试验台的测试原理和组成结构，硬件和软件设计方法，简要介绍了其性能特点和操作方法。     

基于高精度边缘方向求解的红外弱小目标检测

针对边缘方向误差较大导致各向异性 SUSAN 算法背景抑制能力降低的问题,提出了一种高精度边缘方向求解算法来确定实际边缘方向;并引入独立强度模型来确定短轴的尺度以实现滤波器长、短轴自适应地确定。实验表明：高精度边缘方向求解算法的引入能显著提升红外背景重建的精确度,从而提高了算法的背景抑制能力,经过该算法滤波后的图像其信噪比、检测率都获得显著提升,虚警率明显降低,能有效提高系统的单帧红外弱小目标的检测能力。     

减少杂波干扰的可控硅调速电路设计

为了改善传统电机调速系杂波干扰大,系统复杂的缺点,设计一种以工业单片机为核心运算控制芯片,可控硅采用过零检测触发方式,主回路由软件、硬件协调完成,控制可控硅进行电机调速的电路,达到了减少主电路杂渡干扰的目的,控制灵活,系统设计简单,检测和维护方便。     

SCR烟气脱硝自动控制系统及其在三河电厂的应用

论述了国华三河电厂二期2×300MW机组脱硝工程采用的选择性催化还原脱硝工艺。对脱硝系统的工艺环境、控制方案等进行了详细的介绍。     

可逆调速三相可控硅数字触发电路

本文主要介绍了一种三相可逆可控硅速调数字触发电路的原理。其特点是结构简单可靠,精度较高,体积小。用脉冲列触发可控硅。     

Ammonium bisulfate formation temperature in a bench-scale single-channel air preheater

Ammonium bisulfate (ABS) forms in coal-fired power plant exhaust systems when ammonia slip from the NO_x control system reacts with the sulfur oxides and water in the flue gas. The critical temperature range for ABS formation occurs in the air preheater, where ABS is known to cause corrosion and pluggage that can require unplanned outages and expensive cleaning. To develop mitigation strategies for the deleterious effects of ABS in air preheaters, it is important to know its formation temperature and deposition process. This paper describes a bench-scale experimental simulation of a single-channel air preheater, with the appropriate temperature gradient, used in conjunction with simulated coal combustion flue gas, including sulfur oxides, ammonia, and water vapor, to investigate the formation of ABS. Formation was observed optically, and the formation temperature, as well as deposition characteristics for a realistic range of reactant concentrations are presented and compared with previous studies on ABS formation. This study presents data at realistic concentrations not earlier tested, and the reported data has smaller experimental uncertainty than previously obtained. We found that the measured ABS formation temperatures under air preheater channel conditions lies between the temperatures reported by others, and is in the range of 500-520 K for typical flue gas concentrations of ammonia and sulfur oxide species. The results also show that, at least for this experimental configuration, ABS forms predominantly as an aerosol in the gas phase rather than as a condensate on the channel walls.     

The electronic structure of oxide-supported tungsten oxide catalysts as studied by UV spectroscopy

The UV spectra of tungsten oxide catalysts supported on alumina, titania and zirconia, and on titania–alumina and titania–zirconia mixed oxides are reported and discussed. Evidence is provided for the different electronic structure of supports and catalysts, which could affect the behavior of the tungsten oxide centres in the different cases. On alumina, tungsten oxide centres are “isolated” by the insulating support, while on titania-based materials they are likely in electronic contact with each other and with Ti centres through the support conduction band. In the case of WOx2013;ZrO₂, the 5d levels of tungsten ions fall just below of the lower energy limit of the support conduction band. This revised version was published online in July 2006 with corrections to the Cover Date.     

Reduction of NOx over Fe/ZSM-5 catalysts: mechanistic causes of activity differences between alkanes

Fe/ZSM-5 catalysts prepared by sublimation of FeCl₃ onto H/ZSM-5 catalyze the selective reduction of NO_x by hydrocarbons to N₂. The order of the relative rates and N₂ yields obtained with different alkanes reveals a non-trivial chemistry. The maximum yield is lower for propane than for n-butane but about the same for n- and iso-butane. However, at temperatures below this maximum, the N₂ yield is higher for propane and n-butane than for iso-butane. Deposits are formed on the catalyst that contain N atoms in a low-oxidation state which are able to react with NO₂ to form N₂. TPO and FTIR results show that the amount and also the character of the deposits depend on the nature of alkanes. The change of the oxidation state of nitrogen from a high value in NO or NO₂ to a lower value in nitrile and amino groups of the deposit is rationalized by applying mechanistic concepts of organic chemistry, including the Beckmann rearrangement and fragmentation. FTIR spectra and the observed oxygen- and nitrogen-containing compounds by GC-MS are potential clues to the reaction mechanism.     

CFD analysis on the catalyst layer breakage failure of an SCR-DeNOx system for a 350 MW coal-fired power plant

Selective catalytic reduction as one of the secondary NO_x control technologies is widely used in industrial sources including coal-fired power plants and large boilers. The performance of an SCR-DeNO_x system is sensitive to the installment of its components such as turning vanes and hybrid grids. In this work, three-dimensional CFD simulations are carried out to analyze the breakage failure of an SCR-DeNO_x system for a certain 350 MW coal-fired power plant. Research results are consistent with the phenomena that occur in the industrial application. It reveals that the breakage failure in the industrial application is likely to be caused by the inappropriate installation of the turning vane 3 locating closest to the catalyst, especially the angle of the turning vane 3. The analysis further shows that the lifetime or the breakage of the catalyst layers depends highly on the gas velocity, the fly ash distribution and its particle velocity.