暖风器集箱系统并联管组流量偏差因素的研究  

Study on the Factors for Parallel Pipeline Flow Deviation in the Air Heater Collecting Headers

作　　者：徐党旗[1] 侯逊 姬海民 张知翔[1] 周飞[1] 邹小刚 赵治平[1] XU Dangqi;HOU Xun;JI Haimin;ZHANG Zhixiang;ZHOU Fei;ZOU Xiaogang;ZHAO Zhiping(Xi'an Thermal Power Research Institute Co.Ltd.,Xi'an 710054,China;Huaneng Shandong Power Generation Co.Ltd.,Jinan 250014,China)

机构地区：[1]西安热工研究院有限公司,陕西西安710054 [2]华能山东发电有限公司,山东济南250014

出　　处：《中国电力》2018年第2期162-168,共7页Electric Power

基　　金：国家自然科学基金资助项目(51406166);国家科技部科技支撑计划项目(2014BAA07B04)~~

摘　　要：低温省煤器与暖风器联合循环系统是一种能够有效提高机组效率、解决空气预热器堵塞问题的系统,目前在不少电站锅炉上已有应用,取得了较好的效果。但是,在实际应用中,该系统普遍存在流量分配不均匀的问题,尤其在北方冬季会出现暖风器换热管由于流量偏差而导致的冻裂现象,严重影响设备的安全运行。针对该问题,从暖风器内工质流量分配的机理入手,分别建立了基于FLUENT平台的数值计算模型和基于Visual Basic 6.0平台的水动力计算模型。通过大量的计算对比,深入分析了热负荷、工质侧重力、工质流速、管间距、进出口集箱布置位置等参数对换热管流量不均的影响。研究结果表明:随着热负荷的增加,流量偏差显著增大;随着集箱高度的增加,集箱内重力影响增大,流量偏差也会明显变大;随着流速的增加,强制流动在集箱内的作用逐渐增强,弱化了集箱内的重力影响,流量偏差变小。热负荷和重力的耦合作用是导致暖风器内流量偏差的主要原因。最后,基于计算分析的结果,提出了抑制流量偏差的几种方案。研究成果为暖风器的合理设计和解决暖风器换热管冻裂问题提供了有力的技术支持。The low temperature economizer and air heater combined cycle system can improve the efficiency of the power plant boiler effectively and avoid blockage of the air heater system.Its application on the boilers in some power plants has been proved positive.However,the problem of uneven flow distribution is common in practice,which may result in the cracking of the heat exchanger tubes in winter in northern China,and harm the operation of the equipments.To better solve this problem,based on the mechanism of flow distribution of the working fluid in the air heater,this paper proposes a numerical calculation model on FLUENT software platform and a hydrodynamic calculation model on Visual Basic 6.0 platform.Results from the two models are compared.The influence of the heat load,the gravity and velocity of the working,the spacing between the heat exchanger tubes,and the location of collecting headers on the flow distribution in the heat exchanger tubes is analyzed.It is found that the uneven flow distribution is aggravated with the increase of the working fluid velocity.As the elevation of the collecting headers increases,the working fluid gravity plays a more important role and the uneven flow distribution is also aggravated.However,the increase of the velocity incurs a stronger forced flow in the collecting headers,which weakens the effect of the gravity.The coupled effect of the heat load and the gravity is the major cause of the uneven flow distribution in the air heater.Based on the calculation results,several schemes are proposed to prevent the uneven flow distribution.The results of this paper provide some solid technical backup for a better design of an air heater and solve the problem of tube cracking inside the air heaters due to low temperature.

关 键 词：电站锅炉 暖风器 流量不均 重力 热负荷 

分 类 号：TM621[电气工程—电力系统及自动化]