颗粒热物性对煅后焦与换热管传热过程的影响
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摘要
为了探索颗粒热物性对煅后焦与换热管传热过程的影响,基于薄料层式余热回收方法,建立了煅后焦颗粒与换热管的非稳态传热模型,研究了煅后焦导热系数和比热容对传热过程的影响规律。研究结果表明:随着导热系数增加,颗粒堆温降速率和放热速率先增加后减小,在换热(122～161)s时发生的转变,当量导热系数由0.8增至1.2时,平均固相占比由80.05%增加到85.92%,有效换热时间由315 s减小到217 s;随着比热容增加,颗粒堆温降速率和放热速率先减小后增加,在换热121～159s时发生的转变,当量比热容由0.8增至1.2时,平均固相占比差仅为0.2%,有效换热时间呈线性由207 s增至307 s。
In order to explore the effect of particle thermal properties on the heat transfer process between calcined petroleum coke and heat exchanger tube. Based on the waste heat recovery method named thin layer,the unsteady heat transfer model between the calcined coke particles and heat transfer tube was established,and the influence of the thermal conductivity and the specific heat capacity of the calcined petroleum coke on the heat transfer process were studied. The results show that: With the increase of thermal conductivity,the temperature drop rate and exothermic rate increase first and then decrease,the law changes when it is from 122s to 161s. When the equivalent thermal conductivity increases from 0.8 to 1.2,the average ratio of heat transfer through solid wall increases from 80.05% to 85.92% and the effective heat transfer time decreases from 315s to 217s. With the increase of specific heat capacity,the temperature drop rate and exothermic rate decrease first and then increase,the law changes when it is from 121 s to 159 s. When the equivalent specific heat capacity increases from 0.8 to 1.2,the difference of average ratio of heat transfer through solid wall is only 0.2% and the effective heat transfer time increases from 207 s to 307 s.
In order to explore the effect of particle thermal properties on the heat transfer process between calcined petroleum coke and heat exchanger tube. Based on the waste heat recovery method named thin layer,the unsteady heat transfer model between the calcined coke particles and heat transfer tube was established,and the influence of the thermal conductivity and the specific heat capacity of the calcined petroleum coke on the heat transfer process were studied. The results show that: With the increase of thermal conductivity,the temperature drop rate and exothermic rate increase first and then decrease,the law changes when it is from 122s to 161s. When the equivalent thermal conductivity increases from 0.8 to 1.2,the average ratio of heat transfer through solid wall increases from 80.05% to 85.92% and the effective heat transfer time decreases from 315s to 217s. With the increase of specific heat capacity,the temperature drop rate and exothermic rate decrease first and then increase,the law changes when it is from 121 s to 159 s. When the equivalent specific heat capacity increases from 0.8 to 1.2,the difference of average ratio of heat transfer through solid wall is only 0.2% and the effective heat transfer time increases from 207 s to 307 s.
引文
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[4]Barati M,Esfahani S,Utigard TA.Energy recovery from high temperature slages[J].Energy,2011(36):5440-5449.
[5]刘军祥,于庆波,谢华清.冶金渣颗粒余热回收的实验研究[J].东北大学学报:自然科学版,2014(2):245-248.(Liu Jun-xiang,Yu Qing-bo,Xie Hua-qing.Experimental study on waste heat recovery for metallurgical slag particles[J].Journal of Northeastern University:Natural Science,2014(2):245-248.)
[6]王萌.烧结余热竖罐式回收料层换热系数的实验研究[D].沈阳:东北大学,2012.(Wang Meng.Experimental study on heat transfer coefficient of layer in vertical tank for recovering sinter waste heat[D].Shenyang:Northeastern University,2012.)
[7]杨凌,史启才,刘志军.复合肥粒状颗粒移动床传热特性研究[EB].大连:大连理工大学,2007.(Yang Ling,Shi Qi-cai,Liu Zhi-jun.The Heat Transfer Experimentation Research of the Compound Fertilizer Particle in the Moving Bed[EB].Dalian:Dalian University of Technology,2007.)
[8]H Takahashi,H Yanai.Flow profile and void fraction of granular solids in a moving bed[J].Power Technology,1973,7(4):205-214.
[9]Munch-Anderson J.The boundary layer in rough silos[J].Mech.Energy Trans.ME1986,12(3):167-170.
[10]步珊珊,杨剑,李师阳.颗粒接触模型对有序堆积床流动换热影响的数值模拟研究[J].工程热物理学报,2013,34(3):534-537.)(Bu Shan-shan,Yang Jian,Li Shi-yang.Numerical simulation of the influence of particle contact model on flow and heat transfer in an ordered packed bed[J].Journal of Engineering Thermophysics,2013,34(3):534-537.)
[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.(Cen Ke-fa.Theoretical Design and Operation of Circulating Fluidized Bed Boiler[M].Beijing:China Electric Power Publishing House,1998.)
[12]王明强,朱永梅,刘文欣.有限元网格划分方法应用研究[J].机械设计与制造,2004(1):22-24.(Wang Ming-qiang,Zhu Yong-mei,Liu Wen-xin.The research on finite element mesh generation method[J].Machinery Design&Manufacture,2004(1):22-24.)