变频电源在电除尘器提效改造中的应用

高压电源作为静电除尘器的重要组成部分，直接关系到静电除尘器的收尘效率，如何选择高压电源设备对电除尘器的提效改造意义重大。变频电源相对于常规单相晶闸管高压电源、常规三相电源，是最适合的替代产品。与高频电源相比，其除尘性能相近，但稳定性更好，变频电源实现了性能、稳定性的最佳平衡。本文结合工程实例，介绍变频电源在燃煤锅炉配套静电除尘器提效改造项目中的成功应用，实现超低排放。     

哈尔滨发电公司电除尘器提效改造

对中国华电集团哈尔滨发电有限公司3#炉电除尘器运行中存在的问题进行了分析,介绍了BE型静电除尘器的特点和电除尘器提效改造的实施方案。对改造前后电除尘器主要技术指标进行了对比。改造后,电除尘器除尘效率提高。     

300MW燃煤机组全负荷脱硝及超低排放改造技术应用分析

提出脱硝系统全负荷投运、超低排放改造技术,通过锅炉低氮燃烧改造、省煤器烟气调温旁路改造、脱硝催化剂提效,实现燃煤机组全负荷NOx超低排放目标,为同类改造目标的机组提供借鉴。     

移动电极技术在改造项目中的运用

移动电极电除尘器是常规电除尘器的一种改进技术,采用"固定电极电场+移动电极电场"的配置形式。移动电极电除尘器末电场独特旋转的清灰方式,无振打扬尘,能有效保持极板的清洁,彻底解决了二次扬尘问题和返电晕问题,能够大大提高电除尘器效率,从而为电除尘器实现较低粉尘排放提供了一条新的工艺路线。河南某135MW机组在提效改造中采用移动电极技术,最终除尘器出口粉尘排放浓度仅为26.1mg/Nm~3。该工程的实际应用,进一步验证了移动电极技术电厂提效改造工程,特别是场地条件恶劣的项目中,具有明显优势,可为其他类似项目提供参考。     

电袋复合除尘器在除尘增效改造中的应用

近年来,电袋复合除尘技术在燃煤锅炉烟气除尘行业的应用取得了快速发展,并实现了600、1 000 MW大型机组的突破。电袋复合除尘器已成为继电除尘器、袋式除尘器之后的新一代高效除尘设备。实践表明,电袋复合除尘器对煤种变化的适应性强,可长期保持低排放,并具有运行阻力低、占地面积小等优点。介绍了神华阳光2×135 MW CFB机组电除尘器改为电袋复合除尘器的工作机理、基本方案和技术特点,供同类工程参考。     

燃煤电站超低排放综合除尘设计

针对某2×660 MW机组燃煤电站超低排放要求,常规的除尘方案无法满足工程的技术指标。文中以煤质分析为基础,设计了燃煤电站烟尘排放的三级综合除尘方案。即干式除尘器除尘、湿法脱硫装置协同除尘和湿式除尘器除尘的综合除尘方案。比较了三种干式除尘器的特性,介绍了湿法脱硫装置协同除尘和湿式除尘器的除尘机理,合理分配了各级除尘器的进出口参数及除尘效率。通过综合设计,使得烟尘排放不大于2.5 mg/m3。     

燃煤电厂除尘系统超低排放改造

随着国家环保政策的日趋严格,各大燃煤电厂争先恐后的进行超低排放改造。文中先对加装五电场、低低温电除尘、湿式电除尘等除尘提效改造技术进行简单的介绍,然后结合某公司实际情况,对该公司除尘提效改造情况进行分析。     

百万千瓦燃煤机组烟气超低排放设计及应用

为实现燃煤机组烟气超低排放,对某电厂1 000 MW燃煤机组实施烟气超低排放的技术改造:脱硝采用低氮燃烧器调整技术和SCR反应器内加装催化剂技术,除尘采用低低温电除尘器和湿式电除尘器,脱硫采用交互式喷淋技术。改造后机组烟气排放按下述流程:低氮燃烧器的锅炉出口烟气依次流经省煤器、SCR、空预器、管式换热器降温段、低低温电除尘器后进入吸收塔,然后经过湿式静电除尘器和管式换热器升温段进入烟囱。改造后烟囱入口的主要烟气污染物NO_x、烟尘、SO_2排放浓度分别达到25.83、1.61和22.08mg/Nm~3,污染物排放浓度数值上低于天然气燃气轮机组排放标准。     

烟尘排放综合治理技术在某循环流化床机组的应用研究

文章以某循环流化床机组为例,分析了机组存在的烟尘排放浓度偏高问题,提出了高效电源技术与低低温省煤器相结合的烟尘排放综合治理技术。改造完成后,对经济性进行了分析,得出以下结论:高效电源及低低温省煤器改造后,可有效提高电除尘器的除尘效率,烟尘排放浓度由49. 5 mg/Nm~3降低至25 mg/Nm~3。此外,高效电源改造后,除尘器电源的节电效果显著,每年可节约用电61. 6万kW·h;低低温省煤器改造后,除尘器入口烟气温度大幅降低,非供热季可降低除尘器入口烟气温度64℃,降低机组发电标煤耗2. 8 g/(k W·h);供热季可回收热量47 GJ/h。     

330MW亚临界机组节能降耗综合提效技术研究及应用

针对国电江苏谏壁发电有限公司330 MW亚临界机组供电煤耗难以满足《煤电节能减排升级与改造行动计划(2014—2020年)》低于310 g/(kW·h)的要求,在对机组能耗水平全面诊断分析的前提下,提出了汽轮机通流提效改造+锅炉提汽温参数的节能降耗综合提效改造技术方案,改造后汽轮机热耗明显降低,机组330 MW工况下供电煤耗由改造前的324.6 g/(kW·h)降低到300.55 g/(kW·h),本项目改造经验可为同类型机组节能综合提效改造提供参考和借鉴。     

基于神经网络的电除尘器效率在线确定方法

影响电除尘器效率的因素很多,导致电除尘器的效率难以在线确定,基于该问题提出了一种用神经网络构建电除尘器效率模型的新方法．在此神经网络模型中只需要输入锅炉蒸发量、处理烟气量、灰分、粉尘粒径和粉尘比电阻等运行参数,即可实现电除尘器效率的在线测定。仿真表明,该神经网络模型具有良好的逼近实际系统的效果,为电除尘器系统的进一步建模和优化控制提供了参考。     

电除尘高压电源改造技术探讨

高压静电除尘器是依靠电晕电流产生的离子使尘粒荷电,并利用电场力来捕集带电尘粒的,必须设置配套的高压电源形成电场和电晕电流。改造现有电源装置的容量、供电方式和供电特性将直接影响到静电除尘器的除尘效率,以达到国家对环保排放标准,及对电除尘器的性能、降低粉尘排放浓度的要求。     

电除尘器入口速度均布的优化研究

上海某电厂7号炉电除尘器已投运10多年,除尘效率一直较低.通过分析影响除尘效率的各种因素,查阅历史测试数据,认真勘查现场,初步判断入口气流不均匀可能是造成该问题的主要原因.按照10:1比例用透明有机玻璃制作了电除尘器的几何模型,根据相似理论,对电除尘器的入口气流场进行了模化试验,利用彩色烟雾观察了气流的流型,确定了提高...     

集散控制电除尘器除尘效率确定方法的分析与建议

对集散控制电除尘器实时除尘效率的确定方法进行了分析探讨,提出了采用灰平衡法和锅炉的运行参数来计算电除尘器入口烟气含尘浓度,方便地确定电除尘器的实时除尘效率,为电除尘器安全稳定高效运行提供借鉴。     

Reforming of methanol to produce hydrogen over the Au/ZnO catalyst

Gold particle with an average size of d_Au ~ 4 nm was dispersed on ZnO by the deposition precipitation method. The fabricated Au/ZnO catalyst was used to produce hydrogen from reforming of methanol. Four reforming reactions, i.e., decomposition of methanol (DM), steam reforming of methanol (SRM), partial oxidation of methanol (POM) and oxidative steam reforming of methanol (OSRM), were evaluated in a fixed bed reactor. A reaction temperature of T_R > 623 K was required for catalyzing reactions of DM and SRM. Interestingly, high methanol conversion (C_MeOH > 90%) was found from reforming reactions of POM and OSRM at an amazing low temperature of T_R < 473 K. Besides, a presentable hydrogen yield (R_H2 ~ 2.4) and a low selectivity of CO (S_CO ~ 1%) were simultaneously attained from the reaction of OSRM. Therefore, the low temperature OSRM reaction over the Au/ZnO catalyst is suggested as a friendly reforming process for on-board production of hydrogen.     

Biogas upgrade to syn-gas (H2-CO) via dry and oxidative reforming

Fuel reforming processes are primarily used to generate hydrogen for fuel cells and in automotive internal combustion engines to improve combustion characteristics and emissions. In this study, biogas is used as the fuel source for the reforming process as it has desirable properties of being both renewable and clean. Two reforming processes (dry reforming and combined dry/oxidative reforming) are studied. Both processes are affected by the gas stream temperature and reactor space velocity with the second process being affected by O₂/CH₄ ratio as well. Our results imply that oxidative reforming is the dominant process at low exhaust temperatures. This provides heat for the dry reforming of biogas and the overall reforming is exothermic. Increase in O₂/CH₄ ratio at low temperature promotes hydrogen production. At high exhaust temperatures (>600 °C), dry reforming of biogas is dominant and the overall reaction is net endothermic.     

老电厂循环悬浮式半干法脱硫技术应用

针对目前老电厂脱硫工程改造中如何充分利用原有的静电除尘装置这一问题,进行新的设计和尝试,采用半千法脱硫工艺和电-袋串联式收尘器的组合形式,不仅解决了场地不足的问题,而且还充分利用原有的静电除尘器,大大降低了成本,同时脱硫效果也能完全满足设计要求。     

Efficiency assessment of solar redox reforming in comparison to conventional reforming

Solar redox reforming is a process that uses solar radiation to drive the production of syngas from natural gas. This approach caught attention in recent years, because of substantially lower reduction temperatures compared to other redox cycles. However, a detailed and profound comparison to conventional solar reforming has yet to be performed. We investigate a two-step redox cycle with iron oxide and ceria as candidates for redox materials. Process simulations were performed to study both steam and dry methane reforming. Conventional solar reforming of methane without a redox cycle, i.e. on an established catalyst was used as reference. We found the highest efficiency of a redox cycle to be that of steam methane reforming with iron oxide. Here the solar-to-fuel efficiency is 43.5% at an oxidation temperature of 873 K, a reduction temperature of 1190 K, a pressure of 3 MPa and a solar heat flux of 1000 kW/m². In terms of efficiency, this process appears to be competitive with the reference process. In addition, production of high purity H₂ or CO is a benefit, which redox reforming has over the conventional approach.     

Experimental evaluation of methanol steam reforming reactor heated by catalyst combustion for kW-class SOFC

The distributed power generation of methanol steam reforming reactor combined with solid oxide fuel cell (SOFC) has the characteristics of outstanding economic advantages. In this paper, a methanol steam reforming reactor was designed which integrates catalyst combustion, vaporization and reforming. By catalyst combustion, it can achieve stable operation to supply fuel for kW-class SOFC in real time without additional heating equipment. The optimal operating condition of the reforming reactor is 523–553 K, and the steam to carbon ratio (S/C) is 1.2. To study the reforming performance, methanol steam reforming (MSR), methanol decomposition (MD), water-gas shift (WGS) were considered. Operating temperature is the greatest factor affecting reforming performance. The higher the reaction temperature, the lower the H₂ and CO₂, the higher the CO and the methanol conversion rate. The methanol conversion rate is up to 95.03%. The higher the liquid space velocity (LHSV), the lower the methanol conversion rate, the lowest is 90.7%. The temperature changes of the reforming reactor caused by the load change of stack takes about 30 min to reach new balance. Local hotspots within the reforming reactor lead to an excessive local temperature to test a small amount of CH₄ in the reforming gas. The methanation reaction cannot be ignored at the operating temperature. The reforming gas contains 70–75% H₂, 3–8% CO, 18–22% CO₂ and 0.0004–0.3% CH₄. Trace amounts of C₂H₆ and C₂H₄ are also found in some experiments. The reforming reactor can stably supply the fuel for up to 1125 W SOFC.