用户名: 密码: 验证码:
循环流化床中磷石膏还原分解实验研究及数值模拟
详细信息    本馆镜像全文|  推荐本文 |  |   获取CNKI官网全文
摘要
磷石膏是磷酸工业生产的磷酸盐副产物。我国工业副产品磷石膏每年约3000万吨,大量堆存,利用率低。磷石膏由于有害的重金属、硫酸盐、氟硅酸盐、氢氟化物蒸发造成了水体和空气的污染。由于磷酸生产工业和磷石膏堆放对地表水污染造成了很多的环境问题。磷石膏一般的工业处理方法有很多。总结起来一般分为三个方面,即化学法、物理法和热处理法。有时在一个处理磷石膏过程中三种方法都用到。本文针对目前磷石膏分解制硫酸联产水泥技术存在的主要问题,提出以循环流化床作为反应器,用高硫代替焦炭还原分解磷石膏制硫酸联产水泥新技术。
     本文研究主要包括以下三个方面:
     1.磷石膏还原分解反应条件及影响因素研究
     在本研究中,通过利用高硫作为还原剂对磷石膏进行了高温热分解实验,实验、中随着反应温度的升高,磷石膏的分解率与脱硫率升高,磷石膏的分解率达到97%的反应时间逐渐减少。而且在还原性气氛增加的情况下,反应时间会减少。还原性气氛越强,磷石膏的分解率越高,反之,则磷石膏的脱硫率越低,说明磷石膏在弱还原性气氛下分解是较为有利的。
     2.循环流化床工艺流程及参数计算
     对模拟实验所用循环流化床装置及流程进行了详细研究;对磷石膏物料颗粒的临界流化速度、终端速度参数进行计算;同时对流化床实验台分布板、物料循环量进行了分析;对快速床及其特点进行了研究;对由湍流床向快速床以及快速床向密相气力输送床的流型转变进行说明并且对转变速度进行计算。
     3.循环流化床提升管冷态数值模拟计算
     运用大型流体工程计算商业软件Fluent对实验台进行了数值模拟研究,联合使用流体仿真前处理软件gambit进行了网格划分,采用气固两相流欧拉模型和标准k-ε湍流模型,克服了以往由于几何建模困难和模型选择不当问题而导致模拟结果不理想的局限。模拟采用非稳态,分离式求解器,使与实际比较接近。对气速随床高分布、磷石膏物料颗粒体积分数分布、物料颗粒迹线模拟结果分析。当分布板小孔气体进口气速增大时靠近气体分布板附近的气速也有所增大;随着流化风速的增大提升管内物料颗粒体积分数相对减小;当气速增大时,磷石膏物料颗粒在循环流化床中停留时间也相对减少;当气速为65m/s时迹线有折回和回流,也有各线条之间的交叉和混流,这就证明了流体流动的随机性、复杂性和难以预测性。对压力差分布结果、不同流化风速下湍动能、耗散率结果进行分析。当流化风速增大时,沿床高的压力差减小;当流化风速减小时,沿床高压力差增大。随着风速的增大湍动能基本呈降低趋势,而且下段湍动能减小,上段湍动能增大。同时,随着风速的增大湍动耗散率基本呈升高趋势,而且下段湍动耗散率减小,上段湍动耗散率有所增大。
Phosphogypsum is a kind of gypsum that occurs as a by-product and is obtained from phosphate rock during the production of phosphoric acid in fertilizer plants. In view of the problem of phosphogypsum of 30 million tons per year in China, s industry with low utilization and high pile—up. Phosphogypsum causes water and air pollution due to the presence of noxious vapor containing heavy metals, sulphates, fluorosilicates, hydrogen fluorides. Many environmental problems arise throughout the entire chain, one of which is the production of phosphoric acid, which is particularly well-known for the discharge of waste phosphogypsum into surface water and the release of the highly polluting substances. There are various ways to treat phosphogypsums for utilisation in industry. The treatment methods can roughly be divided into three different types, namely, chemical, physical, and thermal methods of treatment. Sometimes a specific process employs a combination of these different approaches to treat the phosphogypsum and convert it into a suitable product for use in industry. This article in view of the current exist major problems in the decomposition of Phosphogypsum to product cement and sulfuric acid techniques, proposed the new technologies of that using high-sulfur coal to replace coke to restore the system decomposition of phosphogypsum to product sulfate and cement in circulating fluidized bed reactor.
     This dissertation is composed of three main parts:
     I Study on the reaction condition and influencing factors of phosphogypsum deoxidization and decomposition.
     In this study, Raise deoxidization and decomposition Phosphogypsum using high sulfur coal on the high temperature. In the experiment with the advance of reaction temperature, the resolution ratio and desulfurization degree of the phosphorus gypsum elevates, the resolution ratio of phosphorus gypsum achieved 97% and reaction time gradually decrease. And in the situation of increasing reducing atmosphere, the reaction time can reduce. Reducing atmosphere stronger, the resolution ratio of phosphorusgypsum higher, otherwise, the desulfurization degree of phosphorusgypsum is lower, we can conclude that the decomposition of phosphorusgypsum is more advantageous under the weak reducible atmosphere.
     II Circulation fluid bed technical process and parameter computation
     Carried out a detailed introduction flow of the simulation experiments using circulating fluidized bed plant; calculated the parameters of the Phosphogypsum material particles' critical fluidization velocity and terminal velocity; At the same time, analyzed the gas distributor of test-bed fluidized bed plate, solid circulating rate; introduced the characteristics of fast bed; carried on the handling bed's flow pattern transformation of turbulent bed to fast bed, as well as fast bed to the dense-phase pneumatic conveying bed and carries on the computation to the transformation speed.
     III Circulating fluidized bed riser cold numerical simulation
     Utilized large-scale fluid engineering calculation commercial software Fluent to conduct the numerical simulation research to the laboratory bench, before the union use fluid simulation, has processed software gambit to carry on the grid division, used was mad that the solid two phase current Euler model and the standard k-e rapids model, haved overcome formerly as a result of the geometry modelling difficulty and the model selection not, when the question caused the analogue result not ideal limitation. The simulation uses the unsteady state, the separation formula solution, causes with actual compared to close. Explained simulation results of the gas velocity follow bed height distribution of phosphogypsum particle, volume fraction distribution of materials, material particles trace. When the distribution of plate holes gas imports gas velocity increases near the gas distributor plate near the gas velocity has also the increase; With the flow of the wind speed increases Riser material particle volume fraction is relatively decreased; when the gas velocity increases, the phosphogypsum material particles in circulating fluidized bed in the residence time is also relatively reduced; When the gas velocity for 65m/s when the trace has to retract and return, but also between the lines cross and Francis, which is proof of the stochastic fluid flow, complexity and unpredictable nature. Analyzed the results of the stress distribution of bad results, under different flow of wind turbulence kinetic energy dissipation rate to. When the flow of the wind speed increases, the stress along the bed height decreases bad; when the flow of the wind speed decreases, the stress along the bed height increased bad. With the wind speed increases the basic turbulent kinetic energy is decreasing, but also reduced lower turbulent kinetic energy, turbulent kinetic energy increases on paragraph. At the same time, as the wind speed increased turbulent dissipation rate was increased the basic trend, but lower turbulent dissipation rate decreases, the upper turbulent dissipation rate has been increased.
引文
[1]冯金煌.磷石膏及其综合利用的探讨[J].无机盐工业,2001,33(4):34-36.
    [2]杨淑珍.磷石膏的改性及其作水泥缓凝剂研究[J].武汉理工大学学报,2003,25(1):23-25.
    [3]郑苏云,陈通,郑林树.磷石青综合利用的现状和研究进展[J].化工生产与技术,2003,10(4):33-36.
    [4]张兴法.磷石膏制备硫酸铵反应动力学研究[J].合肥工业大学学报,2002,25(3):419-422.
    [5]黄岳元.磷石膏废渣生产硫酸钾新工艺研究—磷石膏废渣制备硫酸铵工艺[J].西北工业大学学报(自然科学版),2001,31(1):315-318.
    [6]刘晓红,卢芳仪,孙日圣等.磷石膏制硫酸钾的新工艺[J].化工环保,2001,21(1):29-32.
    [7]丁汝斌,丁广.推荐用磷石膏生产建筑石膏及其制品[J].硫磷设计与粉体工程,2002,(2):30-33.
    [9]李秉政.磷石膏制烧结砖的试验研究及工业化应用[J].磷肥与复肥,2003,18(5):53-55.
    [10]刘代俊.高强度磷石膏砌块的研制[J].磷肥与复肥.2004,19(1):64-65.
    [11]杨三可.用磷石膏生产建筑石膏的新进展[J].硫磷设计与粉体工程,2004,(1):5-7.
    [12]盛厚兴,同继锋.现代建筑卫生陶瓷工程师小册[M].北京:中国建材工业出版社,1998.206-238.
    [13]刘毅,黄新.利用磷石膏加固软土地基的工程实例[J].建筑技术,2002,33(3):171-173.
    [14]张政,谢灼利.流体-固体两相流的数值模拟[J].化工学报,2001,1(52):1-26.
    [15]Harris B J, Davidson J F. Modeling options for circulating fluidized beds:A cor-eannulus depositions model. Circulating fluidized bed TechnologyⅣ,ByA.A.Avid an(ed),American Institute of Chemical Engineers,New York,1994,32-39.
    [16]Asakura K, Asari T, Nakajima I. Simulation of solid-liquid flows in a vertical pipe by a collision model[J].Powder Technology,1997,94(5):201-206.
    [17]Bolio E J, Yasuna J A, Sinclair J L. Dilute turbulent gas-solid flow in risers with particle-particle interactions.AIChEJ,1995,41(6):339-358.
    [18]Segre G, Silberberg A. RadialparticledisplacementsinPoiseuilleflowofsuspensions [J].Nuture,1961,23-230.
    [19]Tsuo Y P. Gidaspow D, Computation of Flow Patterns in Circulating Fluidized Beds.AlChE J,1990,36(6):885-898.
    [20]Patankar N A. Modeling and numerical simulation of particulate flows by the Eulerian-Lagrangian approach. International Journal of Multi-phase Flow,27(2 001):1659-1684.
    [21]Little L,Li Z. Particle Partitioning Strategies for the Parallel Compution of Solid-Liquid Flows. Computers and Mathematics with Applications,2002,43:1591-1616.
    [22]佟桂芳,徐德龙.大颗粒流化床内压力波动现象的仿真研究[J].西安科技学院学报,2002,22(3):259-263.
    [23]Cartland Glover GM.Gas-liquid-solid flow modelling in a bubblecolumn.Chemical Engineering and Processing[J],2004,43 (4):117-126.
    [24]周云龙,孙斌,洪文鹏等.垂直上升管内气液两相环状流截面含气率的数学模型[J].工程热物理学报,2005,26(4):625-627.
    [25]黄远东,吴文权,张红武等.非定常不稳定液固两相流动中漩涡对颗粒运动影响的数值研究[J].水科学进展,2002,13(1):1-8.
    [26]欧阳洁,孙国刚.垂直管道中塞状流的模拟[J].过程工程学报,2003,3(3):193-199.
    [27]Tsuji Y, Kawaguchi T, Tanaka T. Discrete Particle Simulation of Two-dimensional Fluidized Bed[J].Powder Technol,1993,77(1):79-87.
    [28]Xu B H, Yu A B. Numerical Simulation of the Gas-Solid Flow in a Fluldized Bed by Combining Discrete Particle Method with Computational Fluid Dynami-cs[J].Chem.Eng.Sci,1997.52(16):2785-2809.
    [29]Mikami T, Kamiya H, Horio M. Numerical Simulation of Cohesive Powder Behavior in a Fluidized Bed[J].Chem.Eng.Sci,1998,53(10):1927-1940.
    [30]Kawaguchi T, Tanaka T, Tsuji Y. Numerical Simulation of Two-dimensional Fluidized Bed Using the Discrete Element Method(Comparison between the Two-and Three-Dimensional Model)[J].Powder Technol,1998,96(2):129-138.
    [31]Kawaguchi T, Tanaka T, Tsuji Y. Discrete Particle Simulation of Plug Conveying in a Vertical Pipe[A].Proceeding of 6th Intertional Conference on Bulk Materials Storage, Handling and Transportation[C].Australia:The Institution of Engineer-ing,1998.321-327.
    [32]Alder B J,Wainwright T E. Phase Transition for Hard-sphere System[J]. Chem. Phys, 1957,27(5):1208-1209.
    [33]Tsuji Y, Morikawa Y, Tanaka T, etal. Numerical Simulation of Gas-Solid Two-phase Flow in a Two-dimensional Horizontal Channel [J]. Int. J. Multiphase Flow,1987,13(5): 671-684.
    [34]Frank T H, Schade K P,Petrak D.Numerical Simulation and Experimental Investigation of a Gas-Solid Two-phase Flow in a Horizontal Channel[J]. Int. J. Multiphase Flow, 1993,19(1):187-211.
    [35]Hoomans B P B, Kuipers J A M, Briels W J, et al. Discrete Particle Simulation of Bubble and Slug Formation in a Two-dimensional Gas-fluidized Bed:A Hard-sphere Approach[J].Chem. Eng. Sci,1996,51(1):99-108.
    [36]Lun C K, Liu H S. Nmnerical Simulation of Dilute Turbulent Gas-Solid Flows in Horizontal Channels [J]. Int. J. MultiphaseFlow,1997,23(3):575-605.
    [37]Ouyang J, Li J. Particle-motion-resolved Discrete Model for Simulating Gas-Solid Fluldization [J]. Chem. Eng. Sci,1999,54(13):2077-2083.
    [38]Ouyamg J, Li J. Discrete Simulation of Hetergeneous Structure and Dynamic Behavior in Gas-Solid Fluidization[J]. Chem. Eng. Sei,1999,54(22):5427-5440.
    [39]Hoomans B P B. Granular Dynamics of Gas-Solid Two-phase Flow[M]. Netherlands: Maastricht,1999,146-149.
    [40]孙保民,徐旭常.多相流随机轨道数值模拟的概率统计方法[J].工程热物理学报.1995,16(3):358-362.
    [41]Sohn, Chen M M.Microconvective Thermal Conductivity in Disperse Two-Phase Mixtures as Observed in a LOW Velocity Couette Flow Experiment J].Heat Transfer, 1981,103(1):47-50.
    [42]赵镇南,郝睿,王利.液固两相流中微对流强化的机理分析与数值模拟[J].工程热物理学报,2005,26(4):656-658.
    [43]Kuipers J A M, Prins W, Van Saij W P M. Numerical calculation of wall to bed transfer coefficients in gas-fluidized beds[J].AIChE J,1992,38:1079-109 1.
    [44]Li C, Iakkay V. Hydrodynamics and erosion modeling of fluidized bed combust-ors[J]. ASME Trans,1994,116 (3):746-755.
    [45]Liao C M, Lin W Y, Zhou L X. Simulation of particle-fluid turbulence interaction in sudden-expansion flow[J]. Powder Technology,1997,90:29-38.
    [46]Gidaspow D. Multiphase Flow and Fluidization-Continuum and Kinetic Theiry Descriptions[D].New York. Academic Press,1994.
    [47]Sohn C W, Chen M M. Microconvective Thermal Conductivity in Disperse Two-Phase Mixtures as Observed in a LOW Velocity Couette Flow Experiment[J]. Heat Transfer, 1981,103(1):47-50.
    [48]Gupte S K, Advani S G. Role of Micro-Convection Due to Non. AfiHe Motion of Particles in a M ono-Disperse Sus[J].Heat Mass Transfer,1995,38(16):2945-2958.
    [49]陈闽子,佟琦,韩树民.磷石膏、粉灰在硅钙硫肥料生产中的应用[J].中国资源综合利用,2003(9):9-11.
    [50]陈克仁.循环流化床锅炉设计、调试、运行与检修维护技术实用手册.北京:当代中国音像出版社,2005.
    [51]吴占松,马润田,汪展文.流态化技术基础及应用.北京:化学工业出版社,2006.
    [52]金涌,俞芷青,白丁荣,蔡平.流体—颗粒体系流型的划分及其相互间的转变[J]. 化学工程师,1990,3:26-30.
    [53]李佑楚,陈丙瑜,王凤鸣,王永生,郭慕孙.快速流态化流动模型参数的关联[J].化工冶金,1980,4:20-30.
    [54]白丁荣,金涌,俞芷青.循环流化床(Ⅰ)[J].化学工程与工艺,1991,7(2)202-213.
    [55]Yang Y, Chen B, Chen G, Rong S. Proc 1st Int Conf on Measureement and Control of Granulac Materials,1988,140, Shenyang, China.
    [56]孙俊科,杨贵林.循环流化床(Ⅰ).第五届全国流态化会议文集.北京,1990,86.
    [57]Mok S L K. Can J of Chem Eng.1989,67,10.
    [58]Yang G L, Sun J K. Science and Technology. Scieuce Press, Beijing:1991,37.
    [59]毕晓清,金涌,蒋大洲.环流化床流体动力学研究进展[J].化工学报.北京,1990,41.
    [60]J. Drahos, J. Cermok, R. Guardani, K. Schugerl. Characterization of flow regime transitions in a circulating fluidized bed[J]. Power Technology,1988,56,41-48.
    [61]H.K.Versteeg, W.Malalasekera. An Introduction to Computational Fluid Dynamicas: The Finite Volume Method. Wiley, New York,1995.
    [62]陶文铨.数值传热学(第二版).西安:西安交通大学出版社,2001.
    [63]周雪漪.计算流体力学.北京:清华大学出版社,1995.
    [64]郭鸿志.传输过程数值模拟.北京:冶金工业出版社,1998.
    [65]王福军.计算流体动力学分析—CFD软件原理与应用.北京:清华大学出版社,2004.
    [66]Fluent Inc. FLUENT User's Guide. Fluent Inc.2003.
    [67]车德福.多相流及其应用.西安:西安交通大学出版社,2007.
    [68]徐祥,向文国,秦成虎等.流化床密相区流动特性的数值模拟[J].热能动力工程,2004,2:131-133.
    [69]F. C. Lockwood,C. A. Romo-Millanes. Mathematical Modelling of Fuel-NO Emissions From PF Burners[J]. Int. Energy,1992,65:144-152.
    [70]S.A. Morsi,A. J. Alexander. An Investigation of Particle Trajectories in Two-Phase Flow Systems[J]. Fluid Mech.,1972.55(2):193-208.
    [71]M. Syamlal, T. J. O'Brien. Computer Simulation of Bubbles in a Fluidized Bed[J]. AIChE Symp. Series,1989,85:22-31.
    [72]J. M. Dalla Valle. Micromeritics. Pitman, London,1948.
    [73]C.-Y. Wen, Y. H. Yu. Mechanics of Fluidization[J]. Chem. Eng. Prog. Symp. Series, 1966,62:100-111.
    [74]D. Gidaspow, R. Bezburuah, J. Ding. Hydrodynamics of Circulating Fluidized Beds, Kinetic Theory Approach. In Fluidization Ⅶ, Proceedings of the 7th Engineering Foundation Conference on Fluidization,1992,75-82.
    [75]C.-Y. Wen and Y. H. Yu. Mechanics of Fluidization[J]. Chem. Eng. Prog. Symp. Series, 1966,62:100-111.
    [76]S.Ergun. Fluid Flow through Packed Columns[J]. Chem. Eng. Prog.,1952, 48(2):89-94.
    [77]陈甘棠,王樟茂.流态化技术的理论和应用.北京:中国石化出版社,1996.

© 2004-2018 中国地质图书馆版权所有 京ICP备05064691号 京公网安备11010802017129号

地址:北京市海淀区学院路29号 邮编:100083

电话:办公室:(+86 10)66554848;文献借阅、咨询服务、科技查新:66554700