正压气力输送水泥给料稳定性研究

发布时间：2018-05-22 17:31

本文选题：气力输送 + 给料稳定性　；参考：《济南大学》2015年硕士论文

【摘要】：气力输送是利用具有动压能的气体在密封管道中输送粉体颗粒的技术。由于该技术具有设备简单、运行稳定、操作方便易于自动化控制、管道布置灵活等优点,被广泛应用于建材、电力、化工、食品、冶金等行业。气力输送系统根据工作过程中的压力情况可划分为正压压送式、负压吸送式以及两者结合的混合式,其中正压式气力输送由于稳定性优良、可控性好、输送距离长等优点应用较广,较多适用于粉体颗粒物料的输送中.正压开放式气力输送是正压气力输送的重要组成部分,由于其管网布置方便、能耗低等优点广泛应用于水泥粉体的气力输送中。但在实际运行中存在着当物料料位低于某一高度值时,管内的气体压力明显高于料仓内固体粉料产生的静压力,会出现料仓内固体颗粒层被击穿形成腾涌,大大降低管道内的固体浓度与输送能力,而能耗也出现大幅度增局。本论文以日照海汇集团直径为20m,高度为22m的钢板仓内水泥粉体气力输送为研究对象,针对其开放式气力输送装置运行中存在的上述问题,分别在发料仓设计、新型下料装置研发、输送过程自动控制等三个方面开展研究,以期可为本类型气力输送系统的固体给料稳定性提供指导。论文首先根据相似理论和气固两相流动机理设计了仓式泵。在设计过程中研究了粒径、形状、摩擦角以及密度、含水率等物料特性对气力输送的影响。详细研究了气力输送中水泥粉体的物理性能参数。根据两相流理论,在研究气力输送常用的一些参数的基础上,如输送能力、固气比、压力损失等,根据相似理论与日照海汇集团水泥钢板储仓的实际工况设计了新型密闭料仓,所设计的仓式泵能够实现水泥粉体的稳定给料。其次,针对目前海汇集团下料装置所存在的吸力不足的特点,设计开发了文丘里供料器。根据文丘里供料器的工作原理、结构组成和装置特点,在理论上利用质量守恒与能量守恒原理对喷嘴的结构公式、气速和气体质量流量进行推导和研究；在此基础上对文丘里供料器的结构参数进行了研究和分析,对横截面尺寸以及文丘里各组成部件尺寸等结构参数进行了分析和优化设计计算,进而得到具有最优结构的文丘里供料器。最后,论文基于PLC和组态软件设计了一套适用于本类型的气力输送自动控制系统。该自动控制系统采用PLC和上位机组态软件的方式进行设计控制系统。论文PLC的工作方式采用顺序扫描、不断循环的工作方式。根据气力输送工艺流程以及设计整体方案利用STEP 7-Micro/WIN V4.0编程软件编写出PLC程序梯形图并进行仿真运行,并利用基于MCGS的组态控制系统进行了设计,在运行策略中编辑脚本程序,在MCGS运行环境中完成系统的运行调试,模拟仿真发现,该控制系统可以满足开放式气力输送系统的设计要求和实际工程需要。
[Abstract]:Pneumatic conveying is a technique for conveying powder particles in a sealed pipe by using a gas with dynamic pressure. The technology is widely used in building materials, electric power, chemical, food, metallurgy and other industries because of its advantages such as simple equipment, stable operation, convenient operation, easy automatic control, flexible pipeline arrangement and so on. The pneumatic conveying system can be divided into positive pressure delivery, negative pressure suction and a combination of the two according to the pressure situation in the working process, in which the barotropic pneumatic conveying has good stability and controllability. The advantages of long transportation distance are widely used in the transportation of powder particles. Barotropic open pneumatic conveying is an important part of barotropic pneumatic transportation. It is widely used in pneumatic conveying of cement powder because of its convenient pipe network arrangement and low energy consumption. However, when the material level is lower than a certain height, the gas pressure in the pipe is obviously higher than the static pressure generated by the solid powder in the silo. The solid concentration and transport capacity in the pipeline are greatly reduced, and the energy consumption is greatly increased. This paper takes the pneumatic conveying of cement powder in the steel plate silo with the diameter of 20 m and the height of 22 m in the Rizhao Haihui Group as the research object. Aiming at the above problems existing in the operation of its open pneumatic conveying device, the paper designs separately in the sending bin. In order to provide guidance for the solid feed stability of this type of pneumatic conveying system, the research on the development of new discharging equipment and the automatic control of conveying process are carried out. Firstly, a bin pump is designed based on similarity theory and gas-solid two-phase flow mechanism. The effects of particle size, shape, friction angle, density and moisture content on pneumatic conveying were studied. The physical properties of cement powder in pneumatic conveying were studied in detail. Based on the theory of two-phase flow, on the basis of studying some parameters commonly used in pneumatic conveying, such as transportation capacity, ratio of solid to gas, pressure loss and so on, a new type of closed silo is designed according to the similarity theory and the actual working conditions of Rizhao Haihui Group cement steel storage silo. The designed bin pump can realize the stable feed of cement powder. Secondly, the Venturi feeder is designed and developed in allusion to the lack of suction in the blanking device of Haihui Group. According to the working principle, structure composition and device characteristics of Venturi feeder, the structure formula, gas velocity and gas mass flow rate of nozzle are deduced and studied theoretically by means of mass conservation and energy conservation. On this basis, the structural parameters of Venturi feeder are studied and analyzed, and the structural parameters such as cross section size and the dimensions of components of Venturi are analyzed and optimized. Then the Venturi feeder with the optimal structure is obtained. Finally, based on PLC and configuration software, a pneumatic conveying automatic control system is designed. The automatic control system is designed by PLC and PC configuration software. The working mode of PLC is sequential scanning and circulating. According to the pneumatic conveying process and the overall design scheme, the ladder diagram of the PLC program is compiled by STEP 7-Micro/WIN V4.0 programming software and simulated, and the configuration control system based on MCGS is used to design and edit the script program in the running strategy. The running and debugging of the system is completed in the MCGS environment. The simulation results show that the control system can meet the design requirements of the open pneumatic conveying system and the practical engineering needs.
【学位授予单位】：济南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ172.687

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