主蒸汽压力变化对机组煤耗率的影响分析

主蒸汽压力是机组实际运行中必须密切监视和调节的主要参数之一,在机组实际运行中会不可避免的偏离设计值,从而影响机组的发电标准煤耗率,影响机组的热经济性和安全性.在火电厂热经济性统一物理模型和数学模型的基础上,根据多元扰动下的热力系统能效分析模型得到主汽压变化对煤耗率影响的计算模型,并以某电厂660 MW机组为例进行验证,并计算了此机组不同工况下主汽压变化对机组煤耗的影响,并绘制成图,对其规律进行了分析.此计算模型得到的计算结果误差较小,足以满足工程实际的需要.     

超超临界机组加热器端差对煤耗率的影响

准确而快速地评价加热器端差引起的机组热经济性变化,对热力系统的设计、运行和检修具有十分重要的意义.以热力系统热平衡方程、锅炉输入燃料(火用)方程、锅炉吸热量方程、汽轮机输入热(火用)量(火用)方程和汽轮机功率方程为基础,根据小扰动理论和微分理论,得各抽汽量、锅炉输入燃料炯、锅炉吸热量、汽轮机输入热量(火用)和汽轮机功率对端差的变化率.在锅炉(火用)效率、机组炯效率和发电煤耗率概念的基础上,由微分理论推导端差对(火用)经济性指标的影响.以N 1000 - 25/600/600机组为例,计算加热器端差对机组(火用)经济性指标的影响.     

供热机组热电成本及煤耗计算方法的探讨统计修正法的提出

热电联合生产机组的发电成本、供热成本、发电煤耗和供电煤耗的计算是一个有争议的问题。本文提出统计修正法,按照机组所在地区的平均发电成本、供热锅炉平均供热成本、平均发电煤耗和供热锅炉平均供热煤耗的数据什算供热发电机组的成本和煤耗。     

再热汽温变化对煤耗率影响的强度计算模型

再热温度的改变会对机组的热经济性产生影响,文中在火电机组热经济性分析的统一物理模型和数学模型的基础上,推导出了再热汽温对火电机组发电煤耗率影响的通用强度计算模型。该推导方法推导过程简单、物理意义明确,且在应用时只需计算温度变化与强度系数的乘积就可得到煤耗率的变化量。以国产600 MW机组的典型工况为例进行了算例分析,计算结果表明应用该模型在计算时计算量小、精度高。强度系数的提出为火电机组节能降耗以及热力系统定量分析提供了理论依据。     

200MW机组煤耗高的原因及节能改进

介绍国内200MW机组运行现状,并分析机组煤耗高的主要原因,提出机组节能降耗的措施。     

抽汽压损变化对煤耗率影响的通用强度矩阵计算模型

抽汽压损是一种不明显的热力损失,它使蒸汽的做功能力下降,热经济性降低.加热器抽汽压损的变化将影响火电机组的发电煤耗率,因此定量计算分析抽汽压损变化对火电机组发电煤耗率的影响对节能降耗具有重要的现实意义.文中提出了一种计算抽汽压损变化对煤耗率影响的新方法,该方法以火电机组热经济性分析的统一物理模型和数学模型为基础,建立了基于强度矩阵的抽汽压损变化对煤耗率影响的通用计算模型.本模型不必建立热力系统能量平衡方程与质量平衡方程,且推导简单、计算量小、精度高和通用性强,为研究抽汽压损改变对机组热经济性的影响提供了一种新方法.     

超临界600MW机组回热系统变工况对发电煤耗影响的定量分析

以某600MW超临界凝汽式机组为例建立仿真模型,在VWO工况、THA工况、75%THA工况和50%THA工况下模型的计算值与设计值的相对误差小于0.08%。运用模型进行了不同工况下加热器效率、加热器切除、除氧器排汽连续运行、给水泵汽轮机汽源变化4种回热系统变工况对机组发电煤耗影响的定量分析。结果表明,不同负荷工况下,2号高压加热器效率对机组发电煤耗影响更大,其次是1号高加、3号高加、5号低加至8号低加;高压加热器切除对机组发电煤耗影响最大,5号低加至8号低加切除对发电煤耗的影响逐渐减小;除氧器排汽量相同时,机组发电功率越低,对机组发电煤增量的影响越大;给水泵汽轮机采用辅助联箱蒸汽作为汽源时,机组发电功率越高,对机组发电煤耗增量的影响越大。     

电厂运行机组节能经济性评估的方法

以外高桥电厂设计计算煤耗为基础进行经济性分析,综合考虑实际运行中的不可避免损失及当年不可控偏差,得出了电厂机组当前运行条件下可能达到的基准煤耗和当年达标煤耗,并提出了一种运行机组经济性综合评估的技术思路,据此可以了解机组目前的经济性能状况、节能潜力,同时为机组达到经济运行目标提出改进方向。     

基于等价煤耗法的热电联产机组热经济性分析

热电联产机组热经济性代表了热电厂能量利用水平、热功转换技术的先进水平和运行的经济水平,因而准确地分析热电联产机组热经济性显得尤为重要.等价煤耗法是把电厂实际发电效益和供热效益通过热、电等价转换,得到等价发电量,进而得到等价煤耗率.结合300 MW机组,首先分别用热量法、实际焓降法和等价煤耗法对热电联产机组煤耗率进行计算,并通过分析比较,证明了等价煤耗法在评价热电联产机组方面的可行性和准确性;其次比较了同一热电联产机组在供热期和非供热期的煤耗率——供热期煤耗率比非供热期煤耗率低,从而证明了热电联产机组在节能方面优于纯凝机组.     

电站锅炉氧量的变化对煤耗的影响

电厂运行过程中氧量是一个重要的参数.运行氧量的变化对机组的效率及安全性有很大的影响.使用两种不同方法对氧量变化和供电煤耗率的关系进行分析,并使用数据进行了计算.通过分析得出了氧量对煤耗影响的精确计算方法.     

The impact of coal consumption and CO2 emission on economic growth

This study examined the long-run and the causal relationship between total coal consumption, CO₂ emission, and GDP growth in China, the United States, India, Germany, Russia, South Africa, Japan, Australia, Poland, and South Korea. The panel model was employed during the period 1992–2009. The results showed that total coal consumption and CO₂ emission have a long-run relationship with the GDP growth. In addition, there was a short-run positive bidirectional causal relationship between total coal consumption and CO₂ emission. However, total coal consumption and CO₂ emission have no short-run or long-run causal relationship with GDP growth. Thus energy conservation policies on total coal consumption such as rationing energy consumption and controlling CO₂ emissions are likely to have no negative impact on the real output growth of the investigated countries.     

Transportation of US western coal: The impact of deregulation on unit train rates

Unit train rates for coal shipments in the USA are set in a bargaining process between railroads and electric utilities. If either party is dissatisfied with the outcome then the Interstate Commerce Commission may be asked to intervene. However, recent legislation has limited ICC participation in the rate-setting process to cases where competition is proven to be very limited. This article uses a model to estimate unit train rates for coal shipments and the ICC is seen to have been relatively ineffective even in these circumstances. Without competition from other transport modes, in particular slurry pipelines, and with the imposition of increasingly stricter sulphur-emission regulations on utilities, further real increases in unit train rates for western coal shipments could be expected in the future.     

Looking for hysteresis in coal consumption in the US

This paper estimates an unobserved components model to explore coal consumption in the USA. We ask whether coal consumption exhibits hysteresis, defined as a dynamic structure in which the cyclical component of coal consumption has permanent effects on the natural component. In contrast to previous analysis, we provide evidence in favor of hysteresis in coal consumption, by using the nonlinear framework proposed recently by Pérez-Alonso and Di Sanzo [13], in which threshold type nonlinearities are introduced by allowing past cyclical consumption to have a different impact on the natural component depending on the regime. The article discusses implications of the findings for energy conservation policies.     

空气预热器的漏风改造及其节能分析

浙江省共有18台125MW发电机组，均为上海锅炉厂生产的420t/h超高压、中间再热锅炉，每台锅炉配备2台直径6．7m回转式空预器，空预器的漏风率长期超过设计漏风率较多，导致锅炉送、引风机电耗高，锅炉热经济性差。文章分析了长兴电厂4号和5号锅炉空预器漏风率高的原因，通过对空预器的改造使漏风率下降到4．5％左右，机组送、引风机电耗大大下降，锅炉热经济性提高，电厂的发电成本降低。     

线性回归在供电标煤耗分析中的应用

供电标煤耗是评价热电联产企业综合竞争能力的重要指标之一。文中根据某企业供电标煤耗与热电比、汽轮机效率、锅炉效率的对应数据资料,将供电标煤耗与三者之间的变动关系加以模型化,找出并检验回归方程,尝试用回归分析的方法对供电标煤耗进行预测,为热电联产企业降低煤耗,提高市场竞争能力提供依据。     

基于单耗分析法的核电机组能耗分布评价

单耗分析法是基于热力学第二定律以分析产品单耗结构作为降耗指标的能耗评价方法。核电系统遵循单耗分析方法,其能耗评价方式可以分为:标准燃料损耗化及附加单耗分布形式和标准煤耗化及其附加单耗分布形式,体现出不同标准燃料下的能耗分布状况。针对国内最新引进的第三代非能动压水堆AP1000机组进行拓展研究,在保证核电机组安全运行的前提下,提高堆芯对一回路换热温度等级,同时相应提高二回路汽轮机系统工质参数,对提高核电机组效率有显著作用;常规岛中减小蒸汽湿度,有助于降低回热系统能耗。     

ARIMA模型在煤炭消费预测中的应用分析

煤炭属于重要的民用能源,对其消费量进行预测,可为合理安排煤炭生产提供依据,优化社会资源的配置。采用Box和Jenkins的ARIMA模型,对1953年以来我国煤炭消费量的年度数据进行分析。与结构性因果模型、自回归（AR）、移动平均（MA）、自回归移动平均（ARMA）模型等相比较,ARIMA模型不但适合于我国煤炭消费量的非平稳时间序列的特点,并且预测效果比较理想。结果表明,ARIMA（3,1,3）模型的预测效果良好,2002年~2005年平均预测误差仅为3.981%,可用于未来我国煤炭消费量的预测。     

The impact of networking algorithms on the power consumption of routers

In the push towards greener ICT, there is a need to examine the energy savings possible in the design of network infrastructure and each network component. The focus of this paper is to evaluate the impact of routing algorithms on the power consumption of network routers. In a comparison of the power consumption of a number of routers implementing different routing protocols on the open source NetFPGA board, our results show the Bloom filter-based zFilter forwarding node is the greenest router. The rate control protocol (RCP) router and the precision time protocol (PTP) router consume almost identical power, which is about 1.1–1.6% higher than that of the reference router. This higher power consumption of RCP and PTP routers is attributed to the 3.6%–4.7% higher power consumption in the 3.3-V power component of the total power consumption, which is due to the higher router design complexity. Furthermore, we examined the impact of scaling down the core operational clock frequency to demonstrate the merits of energy proportional routing in each of the routers. The zFilter, operating at 62.5 MHz, outperforms the RCP, PTP, and the reference routers operating at 125 MHz, in terms of both packet loss and throughput. In addition, the zFilter operating at 62.5 MHz consumes around 10.9–11.2% less power than the reference router operating at 125 MHz. We analyze the architecture of each router to further explain these results.     

Residual coal exploitation and its impact on sustainable development of the coal industry in China

Although China owns large coal reserves, it now faces the problem of depletion of its coal resources in advance. The coal-based energy mix in China will not change in the short term, and a means of delaying the coal resources depletion is therefore urgently required. The residual coal was exploited first with a lower recovery percentage and was evaluated as commercially valuable damaged coal. This approach is in comparison to past evaluations when the residual coal was allocated as exploitation losses. Coal recovery rates, the calculation method of residual coal reserves and statistics of its mines in China were given. On this basis, a discussion concerning the impacts on the delay of China's coal depletion, development of coal exploitation and sustainable developments, as well as technologies and relevant policies, were presented. It is considered that the exploitation of residual coal can effectively delay China's coal depletion, inhibit the construction of new mines, redress the imbalance between supply and demand of coal in eastern China, improve the mining area environment and guarantee social stability. The Chinese government supports the exploitation technologies of residual coal. Hence, exploiting residual coal is of considerable importance in sustainable development of the coal industry in China.     

On the impact of urban climate on the energy consumption of buildings

Climatic measurements from almost 30 urban and suburban stations as well as specific measurements performed in 10 urban canyons in Athens, Greece, have been used to assess the impact of the urban climate on the energy consumption of buildings. It is found that for the city of Athens, where the mean heat island intensity exceeds 10°C, the cooling load of urban buildings may be doubled, the peak electricity load for cooling purposes may be tripled especially for higher set point temperatures, while the minimum COP value of air conditioners may be decreased up to 25% because of the higher ambient temperatures. During the winter period, the heating load of centrally located urban buildings is found to be reduced up to 30%. Regarding the potential of natural ventilation techniques when applied to buildings located in urban canyons, it is found that, mainly during the day, this is seriously reduced because of the important decrease of the wind speed inside the canyon. Air flow reduction may be up to 10 times the flow that corresponds to undisturbed ambient wind conditions.