高压浓相气力输送中倾斜管阻力特性研究

发布时间：2018-05-07 07:41

本文选题：高压 + 浓相　；参考：《东南大学》2015年硕士论文

【摘要】：我国的一次能源以煤炭为主,煤炭直接燃烧利用热效率较低且产生很多环境问题,煤粉加压气化技术可以实现煤炭资源的清洁利用。高压浓相气力输送技术作为干煤粉气流床加压气化技术中关键技术之一,对整个气化装置的连续稳定运行起着至关重要的作用。在气力输送系统中倾斜管的使用不可避免,高压浓相气力输送中物料浓度高、流动情况复杂,倾斜管内流动情况难以直接观测,现有文献中对倾斜管阻力特性研究较少。本文对高压浓相气力输送中向上倾斜管的阻力特性和输送特性进行了实验研究和理论分析,为高压浓相气力输送系统的设计、调试及运行提供理论支持和数据支撑。论文首先对实验物料(无烟煤和石油焦)的粉体物性进行了系统的测试,包括粉体物料的工业分析、真实密度、堆积密度、含水率、粒径分布和表观形貌。物料的表观形貌分析表明,平均粒径相近的无烟煤和石油焦表观形貌相差较大,无烟煤表面光滑致密,石油焦表面粗糙且附着有小颗粒和片状物。使用ShearTrac-Ⅱ剪切仪对实验物料进行剪切实验。剪切实验结果表明,四种物料的流动函数都在2-4之间,实验物料均属于有黏性物料。物料种类相同时粗颗粒物料的流动性比细颗粒物料好；粒径相近的无烟煤物料流动性比石油焦好。在工作压力高达4.0MPa的气力输送实验装置上以氮气为载气进行了气力输送实验研究,分析了下出料式高压浓相气力输送系统的输送特性,研究了操作参数和粉体物性对输送特性的影响规律。研究结果表明,在相同的输送压差下,随着流化风量的增加,物料的质量流量和固气比先增大后减小,输送稳定性先提高后变差；发送罐压力相同时,随着输送压差的增大,物料输送量不断增大但压差较大时增大趋势减缓,物料固气比先增大后减小,输送稳定性随着输送压差的增大而提高；在相同的输送压力和输送压差下,粗颗粒物料的输送量和固气比均小于细颗粒物料；在相同输送压力和输送压差下,粒径相近的无烟煤物料输送量大于石油焦且无烟煤的输送稳定性更好。运用相图研究高压密相输送过程中不同参数对倾斜管阻力特性的影响规律。研究结果表明,对于倾斜角度一定的管道,物料质量流量相同时,倾斜管压降随着表观气速的增大先减小后增大；在相同表观气速下,倾斜管压降随质量流量的增大而增大；在相同实验条件下,粗颗粒物料的倾斜管压降大于细颗粒物料；质量流量相同时,粒径相近的无烟煤倾斜管压降大于石油焦。在0。-60。的角度范围内,倾斜管压降随倾斜角度的增大不断增大。根据Barth附加压降理论采用量纲分析的方法对倾斜管压降公式进行拟合,获得了倾斜管压降公式。拟合公式预测结果与实验结果吻合较好并推导出在一定的实验条件下倾斜管的临界角约为63。。利用Fluent软件基于双流体模型,采用k-ε-kp-εp湍流模型对高压密相输送中倾斜管内气固两相流流动情况进行了模拟。模拟过程中考虑了两种气固两相流间的相互作用：(1)气固平均速度差引起的气固两相之间的曳力：(2)气相速度脉动和固相速度脉动引起的气固间的湍动能交换。模拟结果表明,在相同的实验条件下,随着表观气速的增大,固相浓度集中的区域会向管道截面中心移动。实验条件相同时,粗颗粒物料固相浓度集中的区域比细颗粒物料更靠近管底。
[Abstract]:In this paper , the experimental research and theoretical analysis are carried out on the physical properties of the high pressure dense phase pneumatic conveying system , including the industrial analysis , the real density , the bulk density , the water content , the particle size distribution and the apparent morphology .
The experimental study on pneumatic transport of anthracite with similar particle size is carried out with nitrogen as carrier gas , and the influence of operating parameters and physical properties on the transport characteristics is studied . The results show that the mass flow and solid - gas ratio of the material decrease first and then decrease after the increase of fluidization air volume under the same conveying pressure difference .
when the pressure of the sending tank is the same , as the conveying pressure difference is increased , the conveying amount of the material is continuously increased , but when the pressure difference is large , the trend is slowed down , the solid - gas ratio of the material is increased firstly , and the conveying stability is improved along with the increase of the conveying pressure difference ;
Under the same conveying pressure and conveying pressure difference , the conveying amount and the solid - gas ratio of the coarse particle material are both smaller than that of fine particulate material ;
The influence of different parameters on the resistance characteristic of inclined tube is studied under the same conveying pressure and conveying pressure difference . The influence of different parameters on the resistance characteristic of inclined tube is studied by using the phase diagram . The results show that the pressure drop of inclined tube decreases with the increase of apparent gas velocity when the mass flow rate of pipeline and material is the same for the inclined angle .
At the same apparent gas velocity , the pressure drop of the inclined pipe increases with the increase of mass flow ;
under the same experimental conditions , the pressure drop of the inclined pipe of the coarse particle material is larger than that of the fine particulate material ;
With the same mass flow , the pressure drop of non - bituminous coal with similar particle size is bigger than that of petroleum coke . In the angle range of 0 . -60 . , the pressure drop of inclined tube increases with the increasing of inclination angle . According to Barth additive pressure drop theory , the formula of pressure drop of inclined tube is fitted , and the formula of pressure drop of inclined tube is obtained . The fitting formula prediction result agrees well with the experimental results and deduces that the critical angle of inclined tube under certain experimental conditions is about 63 . The gas - solid two - phase flow in the inclined tube in high pressure dense phase is simulated by using the two - fluid model . The interaction between gas - solid two - phase is considered in the simulation process : ( 1 ) the drag between gas - solid two - phase caused by the difference of gas - solid average velocity : ( 2 ) the gas - solid phase velocity fluctuation caused by gas - solid average velocity difference and the gas - solid turbulent kinetic energy exchange caused by the solid phase velocity fluctuation .

【学位授予单位】：东南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ536;TQ022.3

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