【作者】 李强；

【导师】 胡亚非；

【作者基本信息】 中国矿业大学 ， 化工过程机械， 2014， 硕士

【摘要】 带式输送机在工业散料输运过程中应用十分广泛，常伴有严重的扬尘问题。备煤车间是焦化厂煤尘污染最严重的工段，产尘形式多样且浓度高。本文依托某焦化厂皮带转运点粉尘治理项目，通过理论分析和模型实验研究，对焦化备煤工段尘源点及设备参数，炼焦煤和煤尘的理化特性，考虑气固相间力的焦化用煤流变特性，皮带转载点煤料的落料属性，诱导气流大小，抽吸动力的上限，以及转运集尘装置的结构等进行研究。从尘源点数量、产尘难易程度、产尘量和粒度分布4个层面详细分析焦化备煤工段的扬尘规律：分析焦化备煤工段落煤产尘形式(定义为皮带互转、皮带转设备、设备转皮带及设备互转4种存在形式)，设备参数以及炼焦煤的理化特性；从浓度和粒度分布角度分析工业现场煤尘运动弥散规律，认为受气相环境和煤料性质的影响，采用集尘罩营造相对封闭独立的空间，对于转载点抑尘扩散是行之有效的方法。从动力学角度分析皮带落煤的流变特性及对扬尘规律的影响：将皮带落煤运动划分为4个特征运动区--平衡区、脱离区、滑动区(或无溜槽时的抛送区)和冲击区；分析煤料在皮带不同输送形式下的抛料位置与抛料速度矢量，不同工况和设备参数下的抛料轨迹和料流形态；计算不同粒度范围煤料的落料末速度，认为绝大多数表层煤在落料过程中都能达到落料末速度；将皮带落煤产尘过程分为分散卷吸区和碰撞挤压区，定性分析诱导气流运动。设计转载落料诱导气流规律探寻实验，为模型实验积累经验。基于相似准则推导出与诱导气流速度相关的两个无量纲准则数：Re和d m2H7p g p A/pg，搭建相似实验平台，建立诱导气流速度的经验模型。通过模型实验，分析单因素(落料高度、溜槽倾角、物料粒度、空气动力黏度、溜槽截面积、落料质量流量、空气含湿量和溜槽截面形状等)下的诱导气流规律，拟合诱导气流速度与各因素间的关系表达式。定义抽吸上限：抽吸气流在能抽走集尘罩内弥散的粉尘情况下，亦要做到不能使已在皮带上沉积煤尘大量起扬，在模型实验的基础上设计起尘量随抽吸风量的关系。根据模型实验，分析负压除尘系统的气源动力最小值应大于诱导气流量：0.25~1.33×10-2m3/s；最大范围不应该超过抽吸上限：2.03~2.21×10-2m3/s。更多还原

【Abstract】 Belt conveyor is actively used in conveying process of industrial for bulkmaterials. But the transfer station of belt conveyor often has the dust phenomenon,especially in the primary products process. Coal preparation shop is the most acuteworking section for dust pollution with high concentration and multiform ways aboutdustproducting in coking plant. In this paper, the dust sources in coal preparation shopand plant parameters, the physical and chemistry properties of coking coal and coaldust, the rheologic characteristics and praticle fluid mechanics, the material throwingtrajectory of coking coal and the quantity of induced air, the upper limit of suction airflow and the dust catching plant’ structure are studied based on the conveyor transferstation dust control program of a coking plant..The dustproducting means in transfer points of coal preparation process whichcontains four means in existence, that are belt to belt, belt to facilities, facilities to beltand dropping from facilities to another, the plant parameters, the physical andchemistry properties of coking coal and coal dust are studied in detail based on threeaspects that are quantities of dust sources, the level of difficulty for dust discharge anddust production. The coal dust dispersion pattern is studied according to theconcentration and particle size distribution of exhausted and position dust. The resultsshowed that dust dispersion is effected by gaseous phase and coking coal’scharacteristics and that it’s useful to construct a sealed space adopting dust catchingplant for dustlaying.The material throwing movement in transfer point is divided into fourcharacteristic movement region that are balance zone, separation zone, sliding zone(or material throwing zone without chute) and impact zone in order to analyze coal’sthrowing location, velocity vectors, throwing trajectory and material flow’s shape indifferent belt transport ways, operating condition and plant parameters from kinematicanalysis. Material throwing attributes in transfer points is analyzed by graphic methodand the centre of gravity place is calculated in order to draw the material throwingtrajectory in different operating condition which contains radius of tumbler, coal’sthrowing location and velocity vectors and drop height, etc. The basic flow behaviorof coal particles in air flow field is studied. The critical particle sizes and droppingterminal velocity of coking coal in different stream boundary is calculated, and it isshowed that the terminal velocities can be expressed approximately as the dropping velocity of coking coal at Stockes region, but the accelerated dropping stage anduniform dropping stage must be considered individually at Allen and Newton region,and almost all coking coal on the surface of material bed can reach to terminalvelocity in transfer points of coal preparation process. Dispersed entrainment zoneand collision extrusion zone are named for dust emission process to analysis inducedair’s movement qualitabively.The rules exploring experiment is designed to study the air entrainmentmechanisms in advance in order to build on experience for the model experiment.Induced airflow velocity which is produced by the dropping of conveyor transferstation material is studied based on the dimensional analysis, two dimensionlesscriteria named Re andd2p m p A/gH7g pnumber related to the induced airflow areset up and the empirical model of induced air velocity is built up. The similarexperiment shows that the induced air velocity has a strong regularity trend with thematerial mass flow velocity, drop height, chute angle, particle size, dynamic viscositycoefficient of air, chute sectional area, air moisture content and chute sectional shapefactor. Relational expression between induced air velocity and the above-mentionedfactors is built up.The upper limit of suction air flow is definition as that the upper limit windvelocity of suction airflow should not blow a large number of dusts which attached tothe materials bed when it is used to replace the raising dust effect of induced airflowby its catching dust effect. An exploring work is designed to study the relationshipbetween quantity of raising dust and suction airflow on the basis of model experiment.Finally, the dymamic force of suction air flow is calculated based on theabove-mentioned model experiments that the quantity of suction airflow shouldgreater than the quantity of induced air which is0.25~1.33×10-2m3/s and notexceeding the upper limit which is in the range of2.03~2.21×10-2m3/s。更多还原