Prediction of high-density polyethylene pyrolysis using kinetic parameters based on thermogravimetric and artificial neural networks

● Reducting the sampling frequency can enhance the modelling process. ● The pyrolysis of HDPE was investigated at three different heating rates. ● The average E_a and k₀ were calculated by Friedman, KAS, FWO, and CR methods. ● ANN was employed to predict the HDPE weight loss with the optimal MSE and R². Pyrolysis is considered an attractive option and a promising way to dispose waste plastics. The thermogravimetric experiments of high-density polyethylene (HDPE) were conducted from 105 °C to 900 °C at different heating rates (10 °C/min, 20 °C/min, and 30 °C/min) to investigate their thermal pyrolysis behavior. We investigated four methods including three model-free methods and one model-fitting method to estimate dynamic parameters. Additionally, an artificial neural network model was developed by providing the heating rates and temperatures to predict the weight loss (wt.%) of HDPE, and optimized via assessing mean squared error and determination coefficient on the test set. The optimal MSE (2.6297 × 10⁻²) and R² value (R² > 0.999) were obtained. Activation energy and pre-exponential factor obtained from four different models achieves the acceptable value between experimental and predicted results. The relative error of the model increased from 2.4 % to 6.8 % when the sampling frequency changed from 50 s to 60 s, but showed no significant difference when the sampling frequency was below 50 s. This result provides a promising approach to simplify the further modelling work and to reduce the required data storage space. This study revealed the possibility of simulating the HDPE pyrolysis process via machine learning with no significant accuracy loss of the kinetic parameters. It is hoped that this work could potentially benefit to the development of pyrolysis process modelling of HDPE and the other plastics.     

压力溶气气浮工艺中溶气效率测定方法述评

气浮工艺中溶气效率高低直接影响到回流水量的大小 ,即决定着运行费用的高低。对气浮工艺设计者和运营者来讲 ,达到并维持较高溶气效率是优先考虑的问题 ,而对新型气浮设备研发者而言 ,了解并确定其在不同工况下的溶气效率也是至关重要的。就已有溶气效率的测定方法进行了分类介绍与评价。     

Effect of flue gas recirculation on nitric oxide (NO) emissions during the coal grate-fired process

Flue gas recirculation (FGR) is a low nitrogen oxide (NO_X) combustion technology. The present study used standard gas to simulate the cycle gas (the main ingredients of which are oxygen (O₂), nitrogen (N₂), and carbon dioxide (CO₂)). The coal grate-fired process was divided into three zones, namely (1) volatilization zone, (2) main combustion zone, and (3) char combustion and burn-out zone. The effects of FGR on coal combustion and NO emissions were investigated in these zones of a unit-boiler experimental system. An industrial test was then conducted on a chain boiler that previously used FGR. Data showed that if the cycle gas was directed into the furnace from the volatilization zone, the curve of the coal surface temperature moved backwards, the temperature peak increased, and coal ignition was delayed. When the FGR rate was 20%, NO emissions/g coal was 41.8% less than in the absence of FGR, in the overall combustion process except for the volatilization zone. An industrial test demonstrated that FGR decreased the NO emissions and incomplete-combustion loss of gas. NO and carbon monoxide (CO) emissions were reduced by 26.9 and 38%, respectively. These observations may prove to be beneficial in reducing ambient air pollution and saving energy.     

腐殖酸还原Fe(Ⅲ)的影响因素研究

研究了腐殖酸还原溶解性Fe(Ⅲ)反应的影响因素,以及腐殖酸对赤铁矿、磁铁矿、针铁矿和钢渣4种含Fe(Ⅲ)矿物的还原作用,探讨了腐殖酸还原溶解Fe(Ⅲ)的反应机制.结果表明,腐殖酸还原溶解性Fe(Ⅲ)的反应符合零级动力学方程.增加腐殖酸或溶解性Fe(Ⅲ)浓度、降低pH或使用可见光照射均能促进反应进行.腐殖酸能直接还原含Fe(Ⅲ)矿物生成溶解性Fe(Ⅱ),对不同含Fe(Ⅲ)矿物的还原效果依次为针铁矿>赤铁矿>磁铁矿>钢渣.红外光谱分析表明,腐殖酸含有的还原性官能团酚羟基和羧基与溶解性Fe(Ⅲ)络合在一起形成稳定的螯合结构,传递电子给溶解性Fe(Ⅲ).溶解性Fe(Ⅲ)得到电子,生成溶解性Fe(Ⅱ).     

烧结法赤泥基本特性的研究

主要运用多种分析检测方法和手段,对山东铝业公司的烧结法赤泥的基本特性进行了深入系统的研究,以期揭示赤泥特性与用途之间的相关关系,为烧结法赤泥综合利用提供必要的基础数据和科学依据。     

中国环境影响评价（EIA）中的公众参与

探讨了中国在环境保护领域中公众参与的政治法律背景、社会机制和优缺点等理论问题，分析了中国ＥＩＡ以及公众参与的形式、内容发生模转变的驱动对发展和加强中国的公众参与提出了一些对策建议。     

时间困境与社会舆论权威——环境管理的权威结构制衡研究

环境资源的稀缺性已经使环境资源配置日益成为引发社会问题的主要变量之一.具有(准)公共物品属性的环境资源配置不合理引发的"公地悲剧"表现在时间轴上即为"时间困境".因为激励机制不足和成本过高等,靠市场机制的产权明晰和政府的强制管理并不能有效的解决环境资源配置的"时间困境".相反,在经济高速发展态势下,目标趋同的政府和企业会在某种程度上形成联合,造成现行环境管理权威结构的失衡.由公众自发形成的社会舆论在合法性前提下,有着解除"时间困境"的内在动因和成本优势,可以发展成为环境资源配置过程的有力的监督要素.要实现环境管理权威结构的内在制衡,还需要从公众内在自觉、外在制度,以及知识协助等三方面对内外环境进行创设.     

任意变截面棒材无模拉伸数学模型的研究

无模拉伸是近年来新开发的一种金属成形工艺。此文在对无模拉伸的发展动态、国内外研究概况等进行综合分析的基础上,分析了任意变截面棒材无模拉伸的变形机制及成形可行性,提出了任意变截面棒材无模拉伸速度或冷热源移动速度的理论计算方法。并提出了几种抛物面棒材无模拉伸的速度模型。经过实验研究证明,此文提出的速度模型较好地表达了任意变截面棒材无模拉伸速度变化规律。     

水解聚合铝溶液中形态分布的定量模拟研究

通过Ａｌ－Ｆｅｒｒｏｎ逐时络合比色法和￣（２７）Ａｌ核磁共振（ＮＭＲ）法，并应用“ＭＩＮＥＱＬ”化学平衡模式计算法，对采用不同反应途径制得的聚合铝（ＰＡＣ）溶液中的化学形态分布规律进行了定量模拟研究和对比。模式计算结果与两种实验定量分析结果都较为吻合，结果表明，在水解聚合铝溶液中较稳定的化学形态主要有五种：一种单体形态［ａｌ＿ａ］，即Ａｌ￣（３＋），Ａｌ（ＯＨ）￣（２＋），Ａｌ（ＯＨ）＿２￣＋；３种聚合形态［Ａｌ＿ｂ］，即和以及一种溶胶或凝胶形态［Ａｌ＿ｃ］，即Ａｌ（ＯＨ）＿３（ａｍ）．这些化学形态的分布和转化不仅取决于溶液的化学特征，而且也取决于制备方法的不同。     

混凝过程中铝与聚合铝水解形态的动力学转化及其稳定性

采用Ｆｅｒｒｏｎ逐时络合比色法，并结合电泳测定研究了混凝过程中氯化铝和聚合氯化铝的水解形态动力学转化及稳定性。结果表明，ＡＣ在混凝过程中所形成的水解形态完全不同于ＰＡＣ的预制水解聚合形态，其电荷及分子量均明显低于聚合铝且不稳定，ＡＣ随混凝条件如投加浓度、ＰＨ和混合时间而变，而ＰＡＣ－２５水解聚合形态不随混凝条件变化，始终保持稳定状态，ＡＣ水解沉淀规律与理论计算相符并形成无定形Ａｌ（ＯＨ）３絮体颗粒