【作者】 李玉刚；

【导师】 刘焕彬；

【作者基本信息】 华南理工大学 ， 制浆造纸工程， 2011， 博士

【摘要】 制浆造纸工业是传统的高能耗产业。随着国际能源形势越来越严峻和国家产业升级步伐的加快,节能减排是造纸企业必须要面对的一个严峻的挑战。单纯的淘汰落后产能已经不是造纸工业应对挑战的最佳方法,如何对现有的产业结构进行优化升级是更为切实有效的思路。纸张的生产本质上是一个脱水的过程。尽管造纸机干燥部脱除了整个过程最少量的水分,但其能耗占整个造纸过程能耗的绝大部分。纸机干燥类型是根据干燥部的结构来划分的,多烘缸造纸机是造纸过程中使用最普遍的一种,大概占到了85~90%。其多烘缸纸机干燥部的能量系统一直是国内外研究的热点。系统的对造纸机干燥部能量系统进行分析和研究对提高造纸企业能效降低成本具有十分重要的意义。本论文首先从造纸企业全厂能量系统入手,利用能量系统“三环节”的基本理论对典型造纸厂的能源流向进行了系统的分析和诊断,继而确定了造纸机干燥部是最大的能耗单元。本研究详细介绍了造纸机干燥部的组成、基本结构以及与其相关的能耗设备,将干燥部分为三个不同的功能子系统,并利用热力学第一和第二定律结合分析能流常用Sankey图对造纸机干燥部能量系统进行了分析。通过对某新闻纸机干燥部的分析结果表明:该纸机空气需求量较大,排出空气的热量很高,达到62.05%,过程?损偏大,达到36.51%。通过对比纸机不同状态能流参数发现:气罩空气湿度参数对干燥过程能耗影响显著。当气罩空气湿度上升时,造纸机干燥部蒸汽消耗可以明显降低。分析了造纸机干燥部能量系统的特点,本研究依据单元模块法建立了多烘缸造纸机干燥部的数学模型。通过数学模型的建立,提出了和干燥部能耗密切相关的烘缸特征函数的确定方法。借助干燥部数据在线采集系统获得的数据在WinPAMS平台上对干燥部模型进行了验证,结果表明,该模型结构合理,模拟运算结果和实测结果基本一致。在建模的基础上,本研究建立了一种造纸机干燥部能量系统的非线性规划模型,提出了造纸机干燥部能量系统的优化方法。该方法把干燥部分成几类不同的功能模块,通过物料和能量平衡分别建立各模块的过程模型,以造纸机实际的操作参数范围作为约束条件,以单位产品能耗最低为目标,借助Matlab软件的相关算法求解能耗最低的过程操作参数。本研究所建立的模型适应性良好,求解方便,可以针对纸机运行参数进行过程用能的优化。将该模型用于优化某箱板纸机和新闻纸机干燥部的过程参数,优化结果表明,现有的操作参数范围内,箱板纸机可以实现节能5.6%,新闻纸机可以根据不同的操作环境进行参数优化,可实现节能6%左右。在线涂布纸机的热回收系统是一个复杂的换热网络。本研究应用夹点技术对某日产1500t的涂布纸机干燥部热回收网络进行了诊断和优化分析。结果表明,该纸机现有的换热网络存在着较大的节能潜力,通过优化改造可以使纸机干燥部的回收热量由原来的4821.6 kJ/s增加到9973.09 kJ/s,节约了干燥部2.3%的蒸汽用量,有明显的节能效果。为了方便夹点技术的应用,本文运用面向对象的技术开了一种计算机辅助程序。该程序的开发提高了运算效率,更利于夹点技术在造纸企业的推广应用。更多还原

【Abstract】 The papermaking industry is a big consumer of energy. As the world’s energy problems become more and more serious, energy consumption reduction in industries is very important. It is a new challenge for the papermaking workers. So improvement of the efficiency without adversely affecting the product quality is very important to the pulp and paper industry.Papermaking is essentially a massive dehydration operation. Although drying removes the least amount of paper in absolute terms, it still remains the most costly and energy intensive step in the papermaking process. The type of dryers used in the paper industry can be classified by the basic means of transferring heat to the paper. An estimate of the distribution of dryer types shows that the conventional steam-heated cylinder dryers are still dominant in paper industry, which reaches a proportion of 85~90%. The energy system of multicylinder dryer section is becoming focus of study. A systematic study on paper machine dryer section has great significance for papermaking industry.The research is beginning from the total plant energy system. The three-link model is used to analyze the energy flow of a typical paper plant. Paper machine dryer section is found to be the most energy consumer. The structure of the dryer section is introduced in details. And it is divided into three subsystems. Energy and exergy balance and Sankey diagram are used together to analyze a newsprint paper machine in this paper. Data from the dry section of the machine is collected to find out the factors affect the energy using efficiency. The result shows that the paper machine needs lots of air to take out the vapor from the wet web. The energy in exhaust air is very high, reaches 62.05%, and the process exergy lose reaches 36.51%. Humidity of hood air has a significant impact on the process energy consumption. When higher hood humidity increasing, lower energy consumption is achieved. According to these characters of the dryer section, the process mathematical model is established. The characteristic function which reflects the relationship between steam consumption and evaporated water is made. By the help of the online data collection system, the model is verified. And the simulation results is in good agreement with the test resultsBased on the mathematical model, by analyzing the characteristics of the energy system of the dryer section in paper machines, a nonlinear programming (NLP) model of the system energy is established, and the corresponding optimization method is proposed. In the method, the dryer section is divided into several functional modules, and the process model of each module is set up based on material and energy balance. By using the operation parameter ranges as the constraints and taking the minimum energy consumption per unit product as the objective, the operation parameters corresponding to the minimum energy consumption are determined with the help of the algorithm presented in Matlab. It is found that the proposed NLP model is well adaptive and convenient for the energy optimization at different operation parameters, concretely. Applied on a linerboard machine which has surface sizing, the method can reduce the energy consumption by 5.6%. For newsprint machines; the energy consumption in the dryer section reduces by about 6%.The heat recovery system of online coating paper machine is a complex heat exchange network. Applied the pinch technology to diagnoses and optimization analysis of heat exchange networks in the drying-section of coated paper machine producing1500 t/d, The result showed that there is a biggish energy-saving potential in the existing heat exchange networks and the quantity of heat-saving in new heat exchange networks after optimizational reforming increased from 4821.6 kJ/s to 9973.1kJ/s, save2.3% fresh steam of drying-section. The energy-saving effect is evident. An object-oriented computer-assisted program is developed for the convenience of the users. The program increases the efficiency and accelerates the application of pinch technology.更多还原