微米级干雾抑尘除尘技术在燃煤电厂的应用

Application of Micron Dry Fog Dust Suppression and Dust Removal Technology in Coal-Fired Power Plant

燃煤电厂输煤系统存在转段落差、设备运转、输送气流、设施老化和密封缺陷等因素,使散粒状煤炭在装卸、输送、筛分、破碎(或磨粉)、转运过程中,发生无规则的摩擦、碰撞、冲击或挤压等时,产生大量的生产性粉尘(主要是煤尘),在紊乱的诱导风作用下从输煤系统不严密处溢出,形成无组织排放的扬尘。煤尘不仅影响作业环境卫生,而且严重损害员工身心健康,还会造成设备损坏、火灾、爆炸等安全隐患。从理论可行性、安全可靠性、技术先进性、现场可操控性、经济合理性等方面,对燃煤电厂输煤系统常用的水喷淋抑尘降尘、旋风除尘、静电除尘、布袋除尘、干雾抑尘除尘等5种技术的优缺点进行比较分析。介绍了微米级干雾抑尘除尘技术在某燃煤热电厂A输煤系统转运站、输煤皮带、煤仓间、干煤棚、渣库和干灰库上的应用实践及运行效果,存在问题及改进措施。同时,对存在的复用水路喷嘴易堵塞、压缩空气管道易带水、输煤皮带机导料槽低碳钢材易腐蚀与磨损等问题,提出针对性的优化改进措施,实践证明此方法取得了良好的效果。4年多的运行实践证明,微米级干雾抑尘除尘技术可在起(抑)尘点形成浓而密的雾池,干雾颗粒可对粉尘颗粒进行有效吸附并聚结成团,实现在起尘点有效抑制粉尘的产生和溢出,抑尘除尘效率超过97%,对PM_(10)呼吸性粉尘的去除效率达90%以上。此外微米级干雾抑尘除尘技术还有以下优点:①输煤系统转运站等作业场所的呼吸性粉尘时间加权平均接触浓度不大于0.50 mg/m^(3)、短时间接触浓度不大于1.00 mg/m^(3),有效降低了作业场所的煤尘浓度,从而减少粉尘职业危害、降低安全生产隐患、改善作业环境,为燃煤电厂抑尘除尘设施优化设计和提升改造提供了切实的实践佐证;②干雾抑尘装置耗水量是水喷淋装置的1%~10%,入炉煤的低位发热量下降了0.022%~0.028%、锅炉热效率下降了0.0012%~0.0024%,对锅炉燃烧和热效率基本没有影响;③此方法可减少输煤系统煤尘外溢量约80%、减少冲洗地面耗水量50%以上,降低了煤炭输送损耗和含尘污水、污泥(煤泥)处置费用,从而降低了企业的生产成本,提升了经济效益、环境效益和社会效益。

There are some problems in the coal conveying system of coal-fired power plant, such as transfer section drop, equipment operation,conveying air flow,aging facilities and sealing defects, so that irregular friction,collision, impact and extrusion etc. will occur in the unloading, transportation, screening, crushing(or milling)and transportation of loose and granular coal, resulting in a large amount of productive dust(mainly coal dust).Under the action of disordered induced wind, it overflows from the lax part of the coal handling system to form fugitive dust. Coal dust not only affects the health of the working environment, but also seriously damages the physical and mental health of employees, and also brings potential safety hazards such as equipment damage, fire and explosion. From the aspects of theoretical feasibility, safety and reliability, advanced technology, feasibility and economic rationality, the advantages and disadvantages of 5 technologies, such as water spray, dust suppression, dust removal, cyclone dust removal, electrostatic precipitator, bag dust removal, dry fog, dust suppression and dust removal, were analyzed and compared. The application practice, effect, existing problems and improvement measures of micron dry fog dust suppression and dust removal technology in a coal conveying system transfer station, coal conveying belt, coal bunker room, dry coal shed, slag silo and dry ash silo of A coal-fired thermal power plant were introduced. At the same time, targeted optimization and improvement measures were put forward for the existing problems, such as easy blockage of reuse waterway nozzle, easy water carrying in compressed air pipeline, easy corrosion and wear of low-carbon steel in guide groove of coal conveyor belt. And the practice showed that this method had achieved good results.More than 4 years of operation practice had proved that, the micron dry fog dust suppression and dust removal technology could form a thick and dense fog pool at the dust starting(suppression)point, and the dry fog particles and dust particles were effectively adsorbed and agglomerated, so as to effectively inhibit the generation and overflow of dust at the dust starting point. The dust suppression and dust removal efficiency was more than 97%, and the removal efficiency of PM10 respirable dust was more than 90%. In addition, there were the following advantages of micron fry fog dust suppression and dust removal technology:(1)The time weighted average exposure concentration of respirable dust in workplaces such as coal handling system transfer station was not greater than 0. 50 mg/m^(3), and the short-term exposure concentration was not greater than 1. 00 mg/m^(3), which effectively reduced the coal dust concentration in workplaces, thereby reducing dust occupational hazards, reducing potential safety production hazards and improving the working environment. It provided practical evidence for the optimization design, upgrading and transformation of dust suppression and dust removal facilities in coal-fired power plants.(2)The water consumption of the dry fog dust suppression device was 1%~10% of that of the water spray device, the low calorific value of the incoming coal decreased by 0. 022%~0. 028%, and the boiler thermal efficiency decreased by 0. 001 2%~0. 002 4%, which had no impact on the boiler combustion and thermal efficiency.(3)The coal dust overflow of the coal conveying system was reduced by about 80%, and the water consumption for flushing the ground was reduced by more than 50%, which reduced the coal conveying loss and the disposal cost of dusty sewage and sludge(coal slime), thus reducing the production cost of the enterprise and improving the economic, environmental and social benefits.