两级式低温烟气换热器运行效果评价

在回热系统中布置低温烟气换热器(GCH)是降低排烟温度和回收热量的有效方式,将烟气换热器分别布置在1 000 MW机组的电气除尘器前和脱硫吸收塔前,研究了烟气换热器投运后机组的性能.结果表明:两级式低温烟气换热器投运后,汽轮机热耗降低了0.56％,供电煤耗降低了1.59 g/(kW·h),同时保证了烟气温度高于其酸露点温度,降低了相关设备的腐蚀风险;在保证脱硫效率的前提下,脱硫系统水耗降低了39.75 t/h;电气除尘器的除尘效率有所提高,出口粉尘平均排放质量浓度降低到14.05 mg/m3,能够满足新的国家排放标准要求;两级式低温烟气换热器有效地实现了机组节能、脱硫系统节水和电气除尘器除尘效率提高的目标,具有良好的应用前景.     

Fly Ash Resistivity Profiling for South African Coal Fired Power Stations

Particulate emission is a major problem in industrial processes, mainly power plants that make use of coal as a primary source of energy. Stringent emissions limits, set by government organisations requires industries to conform to these limits to ensure that air quality is sustained and with minimum pollutant present. Electrostatic precipitators are typically used to filter and collect these particulate emissions. Fly ash resistivity is a primary parameter in the collection of particulate emissions, and there is a resistivity range at which electrostatic precipitator collection is most efficient and anything outside this range limits, their operation. High resistivity ash results in back-corona discharge, whilst low resistivity results in particle re-entrainment into the flue gas stream. The purpose of this paper is to investigate and obtain a fly ash resistivity profile for existing power plants in South Africa. Ash samples obtained from power plants are, tested making use of an ash-resistivity test oven, in accordance with IEEE Standard 548-1984. This paper discusses obtained experimental results, to determine the resistivity profile at which South African power plant electrostatic precipitators operate. The electrical efficiency of the electrostatic precipitator system is evaluated based on the obtained resistivity profiles.     

Coagulation and Collection of PM2.5 Based on a Stack Coagulator

China recently put forward stronger requirements for PM2.5 emission in 2012. Electrostatic precipitators have relatively low efficiency for the collection of submicron particle, especially for PM2.5. An alternate way to increase its efficiency is to enforce the coagulation and, thereby, form larger particles. In this work, we propose an efficient way to enhance the coagulation between oppositely charged particles by using a stack coagulator. Firstly, in order to explore the impact of the bipolar charging and coagulation to the separation efficient of PM2.5, we use system modeling and simulation to explore the whole charge-coagulation-collection process of PM2.5. The results show that the coagulation rate of bipolarly charged particles can be increased by a factor of 10² ～ 10⁴ compared to the neutral particles and the collection efficiency of dust particles increases as the particle size grows. Subsequently, via the dust particles coagulation experiments, the emission rate chart and emission reduction charts of PM2.5 are plotted, which indicate that the average emission reduction of PM2.5 is almost 85%.     

Composition and size distribution of particules emissions from a coal-fired power plant in India

Particulate matter in fly ash from ESP inlet and outlet of a coal fired power plant in India was measured for five units of 120 MW and 210 MW of the power plant. Samples of the pulverised coal and bottom and fly ashes were also collected. The size distribution and chemical composition of particulate matter were determined using a laser particle analyser, an ion chromatograph (IC) and an inductively coupled plasma-atomic emission spectrometer (ICP-AES). The observed particle mass concentration at the ESP inlet was 5443–21483 mg Nm⁻³ whereas the outlet concentration was found as 12–315 mg Nm⁻³ thereby giving total removal efficiency of 95.7–99.8%. A fine particle mode appeared at the particle size of 0.4–0.9 μm and coarse particle mode appeared at the particle size greater than 1 μm. Magnesium and iron remained in bottom ash and showed high concentrations 99 and 2154 μg g⁻¹ (ppmw) respectively, while other elements such as lead, chromium and zinc were observed in higher concentration in ESP inlet flue gas. Relative enrichment of trace elements (except Fe) in fly ash was observed higher than that in bottom ash.     

大型电除尘器的进展

刚产大型硫酸生产用电除尘器的总体结构为板卧式钢壳外保温结构,滚动式平面轴承为支撑构件。阳极均为薄钢板轧制的板状极板,框架式阴极已经取代了重锤挂线式阴极,框架上可安装不同的阴极线。承重绝缘件为95瓷绝缘套管,保温材料为复合硅酸盐毡,厚度仅需100mm。近年来的运行表明,国产大型电除尘器的设备结构和技术性能已达到国外先进水平,有些方面还优于原来进口的设备。大型电除尘器的设计制造和使用都积累了一定的经验,并且仍在不断改进和完善。     

湿式静电除尘器在煤裂解气除尘中的应用

通过工艺参数的确定及设备参数的计算,指出通过相应的工艺配置,湿式静电除尘器应用于煤裂解气的除尘是可行的,其除尘效果明显,可满足除尘工艺要求。     

高温电除尘器在玻璃行业中的应用

针对玻璃窑炉烟气粉尘细、浓度低、具有黏性的特点,采取相应措施,满足平板玻璃生产的排放新标准,并介绍了高温电除尘器在脱硝(SCR)、电除尘和余热发电一体化工程中的应用情况。     

天铁炼铁厂电除尘器的技术改造

针对电除尘器存在的电场电压低、卸灰阀卡死、风机轴承温度高和除尘管道堵塞的问题,详细分析了产生的原因.通过进行一系列的技术改造,电场平均电压上升,风机轴承温度控制在45℃以下,全部风机均可以在高频率下稳定运行,星型卸灰阀卡阻和除尘管道堵塞问题基本得到了解决,电除尘器各参数和性能得到了很大提高.     

几种常见收尘器在精矿预干燥系统中的应用

介绍了几种常见收尘器在精矿预干燥系统中的应用情况,应用过程中遇到的问题及工艺改进。各类常见的收尘方式如:布袋收尘、静电收尘、水沫收尘等广泛应用于精矿预干燥系统中,划分为岗位除尘和精矿预干燥尾气除尘两个应用范围。经过多年来的不断改进,各类收尘器对精矿预干燥系统的适应性得到进一步增强。各类收尘器的稳定使用,减少了工厂的精矿粉尘外排,降低了岗位粉尘污染,改善了周边环境,促进了工厂的环保生产。     

种分槽搅拌系统安装与维修工艺改进

种分槽是氧化铝生产的主要设备之一,其搅拌系统的安装非常关键.分析了种分槽搅拌系统传统安装方法存在的问题,提出了工艺改进方案,并在实际生产中应用,取得了良好的效果.