生物质论文基于生物质碾压成型机理的成型能耗影响因素研究

1、 生物质论文：基于生物质碾压成型机理的成型能耗影响因素研究【中文摘要】生物质固体成型技术可使松散的生物质致密化,变低品位能源为中上等品味能源,已成为规模化利用生物质能源的一种有效途径。但是目前该技术发展存在一些瓶颈,如微观机理研究的欠缺、产品设备能耗过高、设备寿命短等问题,因此,开展相关生物质固体成型技术的研究对于生物质能源的广泛利用具有重要意义。本文以生物质压块成型机为研究对象,以降低生物质压块机能耗为总线,从生物质物料的成型微观机理、环模的静态力学特性及结构参数着手,探求了物料的生物构造、理化性质以及微观力学特性对成型过程的影响规律,提出了碾压成型机理,从微观机理方面降低了生物质成型机能耗

2、；通过成型区受力分析,以求获得最佳环模结构参数；之后基于大变形弹塑性理论,分析生物质成型过程的弹塑性特性,借助于ANSYS有限元分析软件对成型过程进行非线性接触静力学模拟,揭示了物料在成型过程的流变特性及环模与物料的应力应变规律,不仅验证了之前微观机理的正确性,同时为设备结构的优化提供理论依据；最后搭建物料压缩成型试验台,获得了物料成型时最佳的成型条件与工艺参数并验证了有限元模拟结果的正确性。课题以生物质成型的微观机理与大变形弹塑性理论为基础,采用静力学分析、有限元模拟以及现场实验多种研究手段,从物料特性、环模设备结构参数、成型工艺条件多角度探讨如何降低生物质成型能耗。最终,基于应力偏张量理论

3、,提出了碾压成型机理,即增大物料所受的偏张量,促使物料更好地滑移、摩擦、交织,从而减少成型能耗；采用静力学分析方法,获得成型区可实现制块的最佳攫入角与物料高度,得到环模与压辊的直径比及间隙调整准则,并且详尽分析了基于碾压成型机理的物料受力情况,通过对比分析碾压成型与传统方法下物料变形后的微观结构,验证碾压成型机理的正确性；通过有限元模拟计算,揭示了环模成型过程中物料的流变规律,得到物料轴向应力分布规律以及物料所受摩擦力随时间变化图,为生物质成型设备的优化奠定了理论基础；最后采用电子万能实验机,对影响成型的环模转速、环模长径比与环模开口角度以及物料含水率等成型条件与工艺参数进行试验分析,获得了降

4、低生物质成型机能耗的最佳参数。【英文摘要】Biomass briquetting technology can densify loose biomass, significantly improve the energy grade of the source, making it an effective approach to widely utilize biomass resources. However, there are still some development bottlenecks, such as the lack of microscopic mechanism r

5、esearch, high energy consumption, short lifetime of key equipment components, etc. Thus, further research to solve the bottlenecks on the Biomass briquetting technology is imperative.This paper presents a thorough study of briquetting microscopic mechanism and factors of energy consumption, with the

6、 primary purpose to reduce the production energy consumption. Firstly, taking the two aspects of briquetting microscopic mechanism and circular mould Static mechanical as the instruction, biological structures, physical and chemical properties and micro-mechanical properties of biomass raw are resea

7、rched to present the biomass briquetting law and reduce the energy consumption at the source. Also stress on briquetting zone is analyzed to get the optimal structure parameters of circular mould. Then, basic on theory of elastic-plastic large deformation, contact mechanics and viscoelasticity, The

8、finite element model of the biomass briquetting process, a strongly nonlinear problem, is analyzed by the finite element package ANSYS The rheologic and Stress-strain laws are revealed during the process by the simulating. The simulating results are also examined and certified by the self-designed b

9、riquetting experiment platform, which not only illustrate the validity of the microscopic mechanism but also provide the theory basis on structural optimization. The optimal briquetting conditions of the raw are also obtained by the simulating and experimental results.On the basis of biomass briquet

10、ting microscopic mechanism and Elastic-plastic large deformation theory, Factors such as Material Properties, equipment structure parameters and briquetting technological conditions are compositely researched to reduce energy consumption, by using several research methods, including statics analysis

11、, the Finite Element Numerical Simulation and experiment.Finally, rolling forming mechanism is proposed originally based on the stress tensor theory, namely enhancing the global tensor of the materials which makes materials slip, rub and interleave easier, thus the energy consumption is decreased; b

12、ased on the static analysis, the briquetting zone, the swoop angle and the height of the materials and the diameter ratio between the circular mould and press roll are obtained. And the force condition of the materials was analyzed exhaustively. Through the comparative analysis of the microstructure

13、 of the materials formed under the traditional method and rolling forming method, the rolling forming mechanism is validated; based on the FEM simulation, the rheologic law of the materials in the rolling forming processes, the stress distribution law along Y axis and the changing tendency between t

14、he frictional force and the time is revealed, which provide the important theoretical support in the optimization of the structure design; Then the universal stuff experimental equipment is used to conduct the experimental analysis about the briquetting conditions, such as rotational speed, length d

15、iameter ratio of the mould, split taper and moisture ratio and so on, and the technological parameter, and the optimal parameters for reducing the energy consumption are obtained.【关键词】生物质 成型 环模 碾压 有限元【英文关键词】biomass briquetting ring rolling forming ANSYS【目录】基于生物质碾压成型机理的成型能耗影响因素研究目录5-7Contents7-9摘要9-1

16、1Abstract11-12第一章 绪论13-231.1 课题研究背景13-141.2 课题研究意义14-151.3 成型技术国内外研究现状15-201.3.1 压缩成型压力与压缩密度关系研究15-171.3.2 压缩成型过程中的流变学研究17-181.3.3 影响压缩成型的主要因素及成型模具研究18-191.3.4 比能耗的研究19-201.4 存在问题20-211.5 课题研究内容21-23第二章 生物质固体成型微观机理23-372.1 生物质固体成型微观机理23-332.1.1 生物质的基本构造23-262.1.2 生物质的化学性质26-282.1.3 成型过程中生物质内部粒子形变规律2

17、8-302.1.4 成型过程中力学性质30-322.1.5 成型过程的粘接机制32-332.2 玉米秸秆原料特性33-352.3 本章小结35-37第三章 环模的力学特性及对结构的影响37-573.1 低能耗秸秆压块成型设备工作过程简介37-383.2 环模压块成型机工作原理38-403.3 环模压块机能量消耗形式403.4 环模压块机制块的力学条件分析40-443.4.1 攫入角的确定40-423.4.2 物料层高度确定42-443.5 成型区受力状况44-473.5.1 环模受力44-453.5.2 压辊受力45-463.5.3 物料受力46-473.6 环模与压辊尺寸分析47-483.6

18、.1 环模压辊直径比47-483.6.2 环模与压辊工作间隙483.7 成型过程力学分析48-523.7.1 轴向压应力F_L与径向压应力F_R的关系50-513.7.2 轴向压应力F_L与径向压应力F_R沿原料运动方向上的分布规律51-523.8 碾压成型受力规律52-553.9 本章小结55-57第四章 生物质压缩成型过程有限元模拟57-814.1 有限元法简介57-594.2 弹塑性有限元法59-684.2.1 弹塑性变形理论594.2.2 生物质形变流变准则59-644.2.3 弹塑性本构关系64-664.2.4 成型过程非线性接触66-684.3 环模几何模型的建立68-694.4 选取单元类型及定义材料参数69-704.5 建立接触副70-714.6 施加载荷并求解71-724.7 模拟结果分析72-784.7.1 物料的流动变形72-734.7.2 物料的应力和应变73-764.7.3 接触部分摩擦力分布情况76-774.7.4 环模开口角度对压缩成型