下行移动床颗粒流动特性冷模试验研究
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摘要
针对目前大宗固体颗粒余热回收常存在换热不充分、气固流动阻力大、回收得到的余热质量较低等问题,提出了一种气固交叉流动移动床高温颗粒冷却技术方案,并在自行设计的工业级试验装置上利用CFB锅炉炉渣完成了冷态条件下的颗粒流动特性试验研究。通过取样与高速摄影仪拍摄相结合的方式对颗粒流动特性进行测量,分析讨论了颗粒流通截面尺寸对颗粒流动特性的影响和错流段空截面风速对颗粒流动稳定性的影响。结果表明:直流段截面中部颗粒下行速度基本一致,在忽略边壁影响的条件下,计算得到直流段正面和侧面流动指数M_(F1)均大于0. 3,认为直流段颗粒流动为整体流状态;通过对不同位置颗粒取样,发现各取样点颗粒的质量分数最大相差约14. 4%,在实际工程中可认为扩大段颗粒整体流动均匀,但不同位置的颗粒粒径分布存在差异;随着横向风速的增大,颗粒携带速率增大,流过下行移动床的水平风速不能超过1. 45 m/s。
In terms of the problems that exsit in the waste heat recovery of bulk solid particles,such as insufficient heat transfer,high gassolid flow resistance and low quality of the waste heat recovery,a cooling technology for high temperature particle using gas-solid crossflow moving bed was proposed in this study.The experimental study on particle flow characteristics under cold operating conditions was carried out with CFB boiler ash via a self-designed industrial experimental apparatus.Particle flow characteristics were measured by sampling and high-speed photography.The effects of the cross-sectional size of the particle flow on particle flow characteristics and cross-sectional gas speed on particle flow stability were analyzed and discussed.The results show that the downward velocity of particles in the central part of the straight flow section is basically constant. Neglecting the influence of the side walls,the calculated flow index M_(F1) of the front and side section of straight flow section exceed 0.3,which show that the particle flow was considered as a bulk flow under the experimental conditions.By sampling the particles at different locations,it is found that the maximum difference of particle mass ratio is about 14.4%,which could be considered that the particle flow in the enlarged section was uniform in practical engineering,while the particle size distribution at different locations is different.With increasing the transverse air velocity,the particle carrying rate increases.The air velocity in the downward moving bed can not exceed 1.45 m/s.
In terms of the problems that exsit in the waste heat recovery of bulk solid particles,such as insufficient heat transfer,high gassolid flow resistance and low quality of the waste heat recovery,a cooling technology for high temperature particle using gas-solid crossflow moving bed was proposed in this study.The experimental study on particle flow characteristics under cold operating conditions was carried out with CFB boiler ash via a self-designed industrial experimental apparatus.Particle flow characteristics were measured by sampling and high-speed photography.The effects of the cross-sectional size of the particle flow on particle flow characteristics and cross-sectional gas speed on particle flow stability were analyzed and discussed.The results show that the downward velocity of particles in the central part of the straight flow section is basically constant. Neglecting the influence of the side walls,the calculated flow index M_(F1) of the front and side section of straight flow section exceed 0.3,which show that the particle flow was considered as a bulk flow under the experimental conditions.By sampling the particles at different locations,it is found that the maximum difference of particle mass ratio is about 14.4%,which could be considered that the particle flow in the enlarged section was uniform in practical engineering,while the particle size distribution at different locations is different.With increasing the transverse air velocity,the particle carrying rate increases.The air velocity in the downward moving bed can not exceed 1.45 m/s.
引文
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[4]曾兵.循环流化床锅炉选择性排渣冷却系统研究[D].重庆:重庆大学,2012.
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[10]邬万竹.660 MW超超临界CFB锅炉冷渣器选型技术经济性研究[J].洁净煤技术,2017,23(2):103-107.WU Wanzhu.Technical economic study on type selection of slag cooler for a 660 MW ultra-supercritical CFB boiler[J].Clean Coal Technology,2017,23(2):103-107.
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[12]李心宁.篦冷机冷却系统的数值模拟与实验研究[D].青岛:山东大学,2016.
[13]朱建新.基于图像法的流化床内颗粒测试系统及管式流化床内颗粒混合研究[D].杭州:浙江大学,2004.
[14]孙苏皖.气固流化床内宽粒径分布颗粒的流动特性研究[D].重庆:重庆大学,2016.
[15]陶珍东,郑少华.粉体工程与设备[M].北京:化学工业出版社,2010.
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[20]蔡九菊,董辉,傅巍.竖式移动床颗粒流动的研究[J].东北大学学报(自然科学版),2007,28(11):1599-1603.CAI Jiuju,DONG Hui,FU Wei.Study on particle flow in shaft moving beds[J].Journal of Northeastern University(Natural Science),2007,28(11):1599-1603.
[21]孙其诚,辛海丽,刘建国,等.颗粒体系中的骨架及力链网络[J].岩土力学,2009,30(S1):83-87.SUN Qicheng,XIN Haili,LIU Jianguo,et al.Skeleton and force chain network in granular systems[J].Rock and soil Mechanics,2009,30(S1):83-87.
[22]孙其诚,王光谦.颗粒物质力学导论[M].北京:科学出版社,2009.
[2]王美琪.水泥篦冷机高温渗流换热规律及温度预测模型研究[D].秦皇岛:燕山大学,2016.
[3]甘露.循环流化床锅炉双喷动床式冷渣器研究[D].重庆:重庆大学,2014.
[4]曾兵.循环流化床锅炉选择性排渣冷却系统研究[D].重庆:重庆大学,2012.
[5]李朋.高炉渣余热回收及碳资源协同减排应用基础研究[D].沈阳:东北大学,2013.
[6]刘军祥.高炉渣余热回收装置传热特性实验研究[D].沈阳:东北大学,2009.
[7]郑斌,刘永启,李瑞阳,等.高温煅烧石油焦排料过程余热回收[J].化工进展,2015,34(6):1539-1543.ZHENG Bin,LIU Yongqi,LI Ruiyang,et al.Experimental investigation on waste heat reutilization of calcined petroleum coke[J].Chemical Industry and Engineering Progress,2015,34(6):1539-1543.
[8]陈光辉,李升大,陶少辉,等.焦炉余热综合利用研究进展[J].化工进展,2018,37(10):3799-3805.CHEN Guanghui,LI Shengda,TAO Shaohui,et al.Application and research of process of comprehensive utilization of coke oven waste heat[J].Chemical Industry and Engineering Progress,2018,37(10):3799-3805.
[9]范锦忠.提高陶粒回转窑热效率的有效措施[J].墙材革新与建筑节能,2006(11):29-32.FAN Jinzhong.Measure for improving the thermal efficiency of rotary ceramisite kiln[J].Wall Material Innovation and Energy Saving in Buildings,2006(11):29-32.
[10]邬万竹.660 MW超超临界CFB锅炉冷渣器选型技术经济性研究[J].洁净煤技术,2017,23(2):103-107.WU Wanzhu.Technical economic study on type selection of slag cooler for a 660 MW ultra-supercritical CFB boiler[J].Clean Coal Technology,2017,23(2):103-107.
[11]岑可法.循环流化床锅炉理论、设计与运行[M].北京:中国电力出版社,1998.
[12]李心宁.篦冷机冷却系统的数值模拟与实验研究[D].青岛:山东大学,2016.
[13]朱建新.基于图像法的流化床内颗粒测试系统及管式流化床内颗粒混合研究[D].杭州:浙江大学,2004.
[14]孙苏皖.气固流化床内宽粒径分布颗粒的流动特性研究[D].重庆:重庆大学,2016.
[15]陶珍东,郑少华.粉体工程与设备[M].北京:化学工业出版社,2010.
[16]陶贺,金保昇,钟文琪.不同物性对椭球形颗粒在移动床中流动特性影响的模拟研究[J].中国电机工程学报,2011,31(5):68-75.TAO He,JIN Baosheng,ZHONG Wenqi.Effect of particle properties on the flow behaviors of ellipsoidal particles in the moving bed[J].Proceedings of the CSEE,2011,31(5):68-75.
[17]JOHANSON J R,JENIKE A W.Stress and velocity fields in gravity flow of bulk solids[M].Salt Lake City:University of Utah,1962:161-162.
[18]BROWN R L,RICHARDS J C.Kinematics of the flow of dry powders and bulk solids[J].Rheologica Acta,1965,4(3):153-165.
[19]POLDERMAN H G,BOOM J,HILSTER E D,et al.Solids flow velocity profiles in mass flow hoppers[J].Chemical Engineering Science,1987,42(4):737-744.
[20]蔡九菊,董辉,傅巍.竖式移动床颗粒流动的研究[J].东北大学学报(自然科学版),2007,28(11):1599-1603.CAI Jiuju,DONG Hui,FU Wei.Study on particle flow in shaft moving beds[J].Journal of Northeastern University(Natural Science),2007,28(11):1599-1603.
[21]孙其诚,辛海丽,刘建国,等.颗粒体系中的骨架及力链网络[J].岩土力学,2009,30(S1):83-87.SUN Qicheng,XIN Haili,LIU Jianguo,et al.Skeleton and force chain network in granular systems[J].Rock and soil Mechanics,2009,30(S1):83-87.
[22]孙其诚,王光谦.颗粒物质力学导论[M].北京:科学出版社,2009.