dsPIC30F6014的晶闸管触发电路装置设计

介绍了一种基于dsPIC30F6014单片机控制的三相晶闸管触发实验装置,详细阐述了其软硬件结构。测试实验证明,该装置电路简单,产生的触发脉冲稳定性好、触发精度高、易于调试、操作方便、具有实用价值,能够进一步开发用于实验教学。     

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.     

Kinetic modeling of Fe‐BEA as NH3‐SCR catalyst—effect of phosphorous

The focus of this work is to investigate whether a previously developed microkinetic deactivation model for hydrothermally treated Fe‐BEA as NH₃‐SCR catalyst can be applied to describe chemical deactivation of Fe‐BEA due to phosphorous exposure. The model describes the experiments well for Fe‐BEA before and after phosphorous exposure by decreasing the site density, representing deactivation of sites due to formation of metaphosphates blocking the active iron sites, while the kinetic parameters are kept constant. Furthermore, the results show that the activity for low‐temperature selective catalytic reduction (SCR) is very sensitive to loss of active monomeric iron species due to phosphorous poisoning compared to high‐temperature SCR. Finally, the ammonia inhibition simulations show that exposure to phosphorous may affect the internal transport of ammonia between ammonia storage sites buffering the active iron sites, which results in a lower SCR performance during transient conditions. © 2014 American Institute of Chemical Engineers AIChE J, 61: 215–223, 2015     

High activity and wide temperature window of Fe‐Cu‐SSZ‐13 in the selective catalytic reduction of NO with ammonia

Fe‐Cu‐SSZ‐13 catalysts were prepared by aqueous solution ion‐exchange method based on the one‐pot synthesized Cu‐SSZ‐13. The catalysts were applied to the selective catalytic reduction (SCR) of NO with NH₃ and characterized by the means of XRD, UV‐Vis, EPR, XPS, NH₃‐TPD, and so on. The selected Fe‐Cu‐SSZ‐13‐1 catalyst exhibited the high NO conversion (>90%) in the wide temperature range (225–625°C), which also showed good N₂ selectivity and excellent hydrothermal stability. The results of XPS showed that the Cu and Fe species were in the internal and outer parts of the SSZ‐13 crystals, respectively. The results of UV‐Vis and EPR indicated that the monomeric Cu²⁺ ions coordinated to three oxygen atoms on the six‐ring sites and Fe monomers are the real active species in the NH₃‐SCR reaction. Furthermore, the influence of intracrystalline mass‐transfer limitations on the Fe‐Cu‐SSZ‐13 catalysts is related to the location of active species in the SSZ‐13 crystals. © 2015 American Institute of Chemical Engineers AIChE J, 61: 3825–3837, 2015     

煤层气发电高温NO_x烟气SCR处理技术及其应用

煤层气发电是煤层气利用的重要途径之一,但煤层气发电排放的高温尾气中含有大量的氮氧化物(NO_x),会对环境造成污染,需要对其进行脱硝处理,而高温烟气(约500℃)又不宜用V_2O_5/TiO_2蜂窝式催化剂进行直接脱硝处理。为此,在分析比较煤层气发电高温烟气与燃煤发电烟气差别的基础上,应用纳米组装和灌注法研制了GJ-HC-5型催化剂,并通过室内实验确定了脱除NO_x的最佳温度窗口(400~600℃)。之后,在某煤层气电厂进行中间试验,将发电机组高温烟气直接通入到SCR一体化装置进行脱硝处理,在SCR反应器进出口处连续监测,进口NO_x浓度约为620 mg/m~3,出口监测浓度约为20 mg/m~3,对烟气中的NO_x的脱除率始终保持在90%以上。试验结果表明,所研制的高温SCR催化剂符合实际烟气温度条件,且制备方法简单,是一种可行的煤层气发电高温烟气的脱硝方法。     

LED负载恒流驱动电源电路的研究

提出一种由过零检测电路、可控硅整流电路、高频滤波电路与PWM隔离驱动电路组成的非隔离驱动方式的高效LED驱动电源电路。通过可控硅整流器(SCR)控制角α的程控调节与隔离驱动PWM占空比的自适应负载变化,分别实现LED负载恒流驱动的粗调与细调。对各电路模块的仿真与LED负载电流调节实验均验证了系统设计的正确性。     

催化裂化装置还原法烟气脱硝工艺省煤器结垢问题的分析与探讨

还原法脱硝工艺是目前催化裂化装置烟气脱硝处理的主流技术,但目前国内外采用还原法脱硝技术的催化裂化装置中,均面临锅炉省煤器结垢、压降升高进而影响烟机做功甚至造成催化异常停工的问题,作者结合多套项目的设计经验,分别介绍了省煤器结垢的机理、危害和影响因素,并提出了预防和治理措施。     

GP—C_3型高频感应加热设备的技术改造

介绍了高压可控硅整流系统及调压电源     

低温脱硝催化剂研究进展

在传统选择性催化还原技术（SCR）催化剂的基础上,分别以钒-钛系催化剂、固溶体催化剂和新型MnO _x 催化剂为重点介绍了近些年低温SCR催化剂的研究进展,综述了不同活性组分的复合型催化剂的制备方法、元素掺杂、反应机理和抗性等,并通过分析不同复合型催化剂的表征总结了催化剂的性能状况以及低温脱硝效率,着重阐述了新型MnO _x 催化剂所具有的优异脱硝特性,认为通过改性提高新型MnO _x 的抗水抗硫性将会成为该领域未来的发展方向和研究热点,最后介绍了不同负载体对新型MnO _x 催化剂的催化效率的影响规律,发现二氧化钛负载体具有良好的抗水性,三氧化二铝负载体能显著增强催化活性,二氧化铈负载体的热稳定性较好。     

废CeO x -MnO x 基SCR脱硝催化剂还原酸浸综合回收铈锰

废选择性催化还原（SCR）脱硝催化剂中含有大量的有价金属,直接废弃易造成资源浪费及环境污染。以废CeO _x -MnO _x 基SCR脱硝催化剂为原料,采用热力学分析结合湿法冶金实验方法,研究了浸出条件对Ce、Mn元素浸出率的影响。结果表明,废催化剂直接酸浸Ce、Mn元素浸出率低,还原-酸浸Ce、Mn元素热力学条件上可行,抗坏血酸对Ce、Mn高价氧化物有明显的还原作用。当抗坏血酸质量分数为30%、硫酸浓度2mol/L、液固比6∶1、搅拌速度350r/min、80℃恒温反应5h时,Ce、Mn的浸出率分别达到92.09%、95.51%。加入抗坏血酸后,部分Ce⁴⁺和Mn⁴⁺还原为Ce³⁺和Mn²⁺,Ce⁴⁺/Ce的比值由75.82%降低到71.62%,Mn⁴⁺/Mn的比值由29.39%降低到27.17%,同时削弱了高价Ce辅助低价Mn向高价Mn转化的作用,使得Ce、Mn高效浸出,为CeO _x -MnO _x 基废催化剂中Ce、Mn资源化利用奠定了基础。