基于自适应遗传算法参数优化的锅炉燃烧特性建模

近年来,随着节能减排越来越受到关注,燃煤电站锅炉燃烧优化课题得到了广泛的研究,而电站锅炉燃烧特性建模是燃烧优化课题研究的基础和关键。文中采用混合核函数构造最小二乘支持向量机（LS—SVM）,为了提高该支持向量机回归模型的精度,通过自适应交叉和变异的改进型遗传算法对模型参数进行全局寻优。计算结果表明,根据本文方法建立的燃烧模型很简洁,精度较高,只需要应用少量的训练样本就能比较精确的预测锅炉的燃烧特性,具有较显著的工程应用价值。     

电站锅炉燃烧优化技术的发展趋势

燃烧优化技术是实现电站锅炉高效燃烧和污染物控制的最经济、最有效的方法之一.通过在对国内外电站锅炉燃烧优化技术研究现状综述的基础上,还对燃烧技术的发展趋势进行了展望.燃烧优化技术研究主要表现在线测量仪表、非线性动态建模、多元优化目标、专家系统和闭环系统等方面,将混沌理论、分形理论、场协同理论、灰色系统理论和数据挖掘理论等科技前沿技术应用到电站锅炉燃烧优化的研究中,将会大大拓展燃烧优化的研究空间,给燃烧优化的研究带来新的生命力.     

电站锅炉制粉系统模型的建立与应用

为了准确计算燃煤电站锅炉在运行过程中实时入炉煤量,并将计算结果提供给燃煤热值在线辨识系统,针对300 MW电站锅炉制粉系统,采用机理建模的方法建立了制粉系统模型。模型的参数设定与制粉设备的结构数据及锅炉侧运行数据相关,从而使模型具有可扩展性。利用在线运行数据的验证结果表明,制粉系统模型的引入可以显著改善燃煤热值辨识的动态性能,对提高电站控制品质有潜在应用价值。     

基于PLS和ε-FT的电站锅炉NO_x排放特性研究

为了有效控制电站锅炉的NO_x排放量,以某600 MW电站锅炉历史运行数据为样本,应用偏最小二乘(PLS)和ε-模糊树(ε-FT)方法建立了NO_x排放特性模型.针对热工过程变量之间的强相关性和耦合性,采用PLS对模型输入热工数据进行重要变量信息提取和变量选择,将得到的最优变量作为ε-FT模型的输入,建立了NO_x排放特性的PLS-ε-FT模型,并将模型与其他建模方法进行对比.结果表明:该模型通过PLS进行变量选择,消除了变量的相关性,降低了模型的维数和复杂程度,提高了模型的预测精度和泛化能力.     

反向建模方法在火电厂关键参数建模中的应用

提出在火电厂关键参数建模中采用反向建模方法,以规避传统建模方法在实际应用中的建模难题.以超临界直流锅炉中间点温度为例,利用桌600MW超临界机组的实际运行数据,采用反向建模方法建立了该参数的数学模型.建模算法选用最小二乘支持向量机(LS-SVM),应用粒子群算法(PSO)解决了 LS-SVM 参数寻优问题,并将 PSO-LS-SVM 所得模型与 LS-SVM、偏最小二乘(PLS)以及BP神经网络所得模型进行了对比,结果表明:基于PSO-LS-SVM 的中间点温度数学模型计算速度快、精度高,验证了反向建模思想的有效性和可行性.     

基于动态标杆值的电站锅炉燃烧控制优化

目前锅炉燃烧控制主要依靠人工手动调整，为解决运行经验差异导致锅炉燃烧性能差异的问题，提出了一种基于动态标杆值的电站锅炉燃烧控制优化方法。在建立燃烧模型的基础上，以归一化经济与环保指标得到综合效益因子作为寻优判据，对历史工况进行数据挖掘，实现全工况下基于动态标杆值的运行参数自主寻优和更新，使锅炉燃烧、污染物排放相互协调。该方法已于某燃煤电站成功实践，结果表明：在应用案例中，寻优推送后综合效益因子提高了4.34%,使得锅炉热效率和NO_x排放质量浓度相互协调更优。     

旋流器流量分配对燃气轮机燃烧性能的影响研究

目前锅炉燃烧控制主要依靠人工手动调整，为解决运行经验差异导致锅炉燃烧性能差异的问题，提出了一种基于动态标杆值的电站锅炉燃烧控制优化方法。在建立燃烧模型的基础上，以归一化经济与环保指标得到综合效益因子作为寻优判据，对历史工况进行数据挖掘，实现全工况下基于动态标杆值的运行参数自主寻优和更新，使锅炉燃烧、污染物排放相互协调。该方法已于某燃煤电站成功实践，结果表明：在应用案例中，寻优推送后综合效益因子提高了4.34%，使得锅炉热效率和NOx排放质量浓度相互协调更优。     

电站燃煤锅炉NOx排放神经网络模型

人工神经网络具有联想、记忆、并行计算、自适应、自学习、适于处理非线性问题等优点.电站燃煤锅炉NOx排放规律非常复杂,很难对其进行建模.提出电站燃煤锅炉NOx排放量的神经网络模型,该神经网络模型具有可以预测各一次风粉单元NOx生成量、锅炉NOx排放量、网络隐节点数少、泛化能力强、鲁棒性好、学习速度快的优点.所提出的模型可以为大型电站锅炉通过燃烧系统自动调整或结构改造降低NOx排放提供依据.     

一种改进型LSSVM模型在电站锅炉燃烧与优化中的应用

采用鲁棒交叉验证算法对传统最小二乘支持向量机模型进行改进,并对某350 MW机组的锅炉燃烧系统进行建模,用以预测锅炉出口烟气参数的变化。结果表明:鲁棒交叉验证最小二乘支持向量机建模方法提高了模型的预测精度,增强了模型的鲁棒性,有效避免了单一元素误差对预测结果的影响;通过优化锅炉燃烧系统输入参数的组合,可以有效提高锅炉的整体经济效益并降低NOx的生成量。     

最小二乘支持向量机在煤着火特性研究中的应用

为避免煤热失重反应静态燃烧过程获取的燃烧参数与实际锅炉动态燃烧之间的误差,以及解决沉降炉实验工作量大、难以对所有煤种进行试验的问题,利用最小二乘支持向量机建立了煤粉着火特性模型,通过对热失重反应过程的机理分析确定最佳输入变量,并进行仿真实验.结果表明:利用热失重反应过程数据预测煤着火性能具有较高的预测精度,可以在实际中应用,指导大型电站锅炉及燃烧装置的设计和运行.     

Performance assessment of some ice TES systems

In this paper, a performance assessment of four main types of ice storage techniques for space cooling purposes, namely ice slurry systems, ice-on-coil systems (both internal and external melt), and encapsulated ice systems is conducted. A detailed analysis, coupled with a case study based on the literature data, follows. The ice making techniques are compared on the basis of energy and exergy performance criteria including charging, discharging and storage efficiencies, which make up the ice storage and retrieval process. Losses due to heat leakage and irreversibilities from entropy generation are included. A vapor-compression refrigeration cycle with R134a as the working fluid provides the cooling load, while the analysis is performed in both a full storage and partial storage process, with comparisons between these two. In the case of full storage, the energy efficiencies associated with the charging and discharging processes are well over 98% in all cases, while the exergy efficiencies ranged from 46% to 76% for the charging cycle and 18% to 24% for the discharging cycle. For the partial storage systems, all energy and exergy efficiencies were slightly less than that for full storage, due to the increasing effect wall heat leakage has on the decreased storage volume and load. The results show that energy analyses alone do not provide much useful insight into system behavior, since the vast majority of losses in all processes are a result of entropy generation which results from system irreversibilities.     

Effect of co-cultivation of Chlamydomonas reinhardtii with Azotobacter chroococcum on hydrogen production

Chlamydomonas reinhardtii cc124 and Azotobacter chroococcum bacteria were co-cultured with a series of volume ratios and under a variety of light densities to determine the optimal culture conditions and to investigate the mechanism by which co-cultivation improves H₂ yield. The results demonstrated that the optimal culture conditions for the highest H₂ production of the combined system were a 1:40 vol ratio of bacterial cultures to algal cultures under 200 μE m^?2 s^?1. Under these conditions, the maximal H₂ yield was 255 μmol mg^?1 Chl, which was approximately 15.9-fold of the control. The reasons for the improvement in H₂ yield included decreased O₂ content, enhanced algal growth, and increased H₂ase activity and starch content of the combined system.     

Exergetic evaluation of 5 biowastes-to-biofuels routes via gasification

This paper presents the exergy analysis results for the production of several biofuels, i.e., SNG (synthetic natural gas), methanol, Fischer–Tropsch fuels, hydrogen, as well as heat and electricity, from several biowastes generated in the Dutch province of Friesland, selected as one of the typical European regions. Biowastes have been classified in 5 virtual streams according to their ultimate and proximate analysis. All production chains have been modeled in Aspen Plus in order to analyze their technical performance. The common steps for all the production chains are: pre-treatment, gasification, gas cleaning, water–gas-shift reactions, catalytic reactors, final gas separation and upgrading. Optionally a gas turbine and steam turbines are used to produce heat and electricity from unconverted gas and heat removal, respectively. The results show that, in terms of mass conversion, methanol production seems to be the most efficient process for all the biowastes. SNG synthesis is preferred when exergetic efficiency is the objective parameter, but hydrogen process is more efficient when the performance is analyzed by means of the 1st Law of Thermodynamics. The main exergy losses account for the gasification section, except in the electricity and heat production chain, where the combined cycle is less efficient.     

液压系统常见的故障诊断及处理

任何工程机械式液压设备使用时出现故障是不可避免的。但是怎样确定故障的原因及找到好的解决方法，这是使用者最关心的问题。讲述了液压系统常见的故障及其排除方法。     

Economie d'énergie en trigénération

Trigeneration is defined as the production of three useful forms of energy—heat, cold and power—from a primary source of energy such as natural gas or oil. For instance, trigeneration systems typically produce electrical power via a reciprocating engine or gas turbine and recover a large percentage of the heat energy retained in the lubricating oil, exhaust gas and coolant water systems to maximize the utilization of the primary fuel. The heat produced can be totally or partially used to fuel absorption refrigerators. Therefore, trigeneration systems enjoy an inherently high efficiency and have the potential to significantly reduce the energy-related operation costs of facilities. In this paper, we describe a model of characterization of trigeneration systems trough the condition of primary energy saving and the quality index, compared to the separate production of heat, cold and power. The study highlights the importance of the choice of the separate production reference system on the level of primary energy saving and emissions reduction.     

Mineralogical characterization of the intraseam layers of Lofoi lignite deposits in Florina basin (western Makedonia,northwest Greece)

The mineralogical composition of intraseam layers from Lofoi lignite deposits (northwest Greece) is the subject of the present study. The samples were examined by means of X-ray diffraction (XRD), thermo-gravimetric (TG/DTG) and differential thermal analysis (DTA), and Fourier transform infrared (FT-IR) spectrometry. The clay minerals prevail in most samples, with illite-muscovite being the dominant phase, and kaolinite and chlorite being the other major clay components. No smectite was found. Quartz and feldspars, dominate in two cases. The studied materials are characterized as clays to clayey sands, showing significant similarities with the intraseam layers of the adjacent Achlada lignite deposits.     

Innovative methodologies in renewable energy: A review

This paper is concerned with innovative approaches to renewable energy sources computation methodologies, which provide more refined results than the classical alternatives. Such refinements provide additional improvements especially for replacement of fossil energy usages that emit greenhouse gas (GHG) into the atmosphere leading to climate change impact. Current knowledge gap among each renewable energy source calculation is rather missing fundamentals of plausible, rational, and logical explanations for the interpretation of results. In the literature, there are rather complicated and mechanically applicable methodologies, which require input and output measurement data match with missing physical explanations. The view taken in this review paper is to concentrate on quite plausible, logical, rational, and effectively applicable innovative energy calculation methodologies with simplistic fundamentals. For this purpose, a set of renewable energy methodological approaches is revisited with their innovative structures concerning solar, wind, hydro, current, and geothermal energy resources. With the increase in the renewable energy utilizations to combat the undesirable impacts of global warming and climate change, there is a need for better models that will include physical environmental conditions and data properties in the probabilistic, statistical, stochastic, logical, and rational senses leading to refined and more reliable estimations with application examples in the text. Finally, new research directions are also recommended for more refined innovative energy system calculations.     

Constrained Optimization of Heat Transfer from an Extended Surface

Two different zero‐order optimization techniques are used to maximize the rates of heat transfer from a fin assembly of a specified cost and in the shape of several annular fins that are mounted on a central stem. The problem is formulated to account for two‐dimensional steady‐state heat transfer that is limited by several inequality constraints. The dimensionless governing equations are used to identify the relevant decision variables. The number of fins making up the assembly is treated as an input parameter. A digital computer is used to determine the required temperature distributions and to implement the optimization search algorithms. Three different fin materials are assessed—aluminum, copper and carbon steel. Design optimizations of the extended surface assembly were made over a range of operating conditions, encompassing several different convection heat transfer coefficients that are representative of free and forced convection in air, and several different overall temperature differences between the substrate surface and air. A few recommendations based on trends in the predicted results are given. © 2013 Wiley Periodicals, Inc. Heat Trans Asian Res, 43(6): 504–521, 2014; Published online 3 October 2013 in Wiley Online Library ( wileyonlinelibrary.com/journal/htj ). DOI 10.1002/htj.21093     

CY6D78Ti型柴油机的开发研制

本文介绍了CY6D78Ti型柴油机的开发研制过程及现状,CY6D78Ti型柴油机能满足国内中、重型卡车和豪华客车市场对柴油机动力性、经济性、可靠性的需求。由于该机型的高档配置,保证了其排放达到欧Ⅱ标准,同时为进一步提高性能、降低排放,采用电控及高压共轨等技术手段搭建了平台。     

我国车用柴油机的技术现状及发展趋势

本文根据国内外信息和资料，分析了我国目前车用柴油机制造技术方面与国际水平所存在的差距，预测今后若千年内车用柴油机要向节能降耗、应用增压技术、提高可靠性、降低排放、采用电控技术方面发展，以尽快接近和赶上国际先进水平．