包含环境影响的能量系统火用经济学理论分析

能量生产过程中总会有残留物质和能量排放到大气中,对环境产生影响.本文从能量系统的火用平衡出发,将系统对环境的排放火用从火用损失中分离出来,依据符号火用经济学的原理建立了包含环境影响在内的系统火用、火用成本和火用经济学成本分析模型,并以燃气轮机功热并供(CGAM)系统为例推导出了矩阵求解方程,从而得出了能量系统的技术、经济和环境的火用经济综合分析模型.     

包含环境影响的能量系统Yong经济学理论分析

能量生产过程中总会有残留物质和能量排放到大气中，对环境产生影响。本文从能量系统的烟平衡出发，将系统对环境的排放火用损失中分离出来，依据符号火用经济学的原理建立了包含环境影响在内的系统火用，火用成本和火用经济成本分析模型，并以燃气轮机功热并供（CGAM）系统为例推导出了矩阵求解方程，从而得出了能量系统的技术、经济和环境的火用经济综合分析模型。     

600MW超临界燃煤锅炉分析

煤炭一直以来都是中国最主要的一次性能源,相应地,燃煤锅炉也占有电力市场绝大部分份额。燃煤锅炉存在诸多能量损失途径,能量转换效率较低。系统地分析燃煤锅炉的热力性能非常必要。是热力学第二定律中的一个重要概念,它不仅能反映能量的数量,更能反映能量的品质。基于概念,对某600MW超临界燃煤锅炉模型进行了详细的分析,综合考虑物理和化学,计算了系统的损失、耗散等参数,对锅炉的设计、优化提供了可靠依据。     

基于效率的综合能源系统能效分析模型

基于热力学第一定律的"能量分析"与基于热力学第一以及第二定律的"分析"方法是两种主要的热效率评价方法。以能源互联网能源侧重要组成部分-综合能源系统为研究对象,构建了不同类型综合能源系统能量分析与分析数学模型,对北京市亦庄路南区能源互联网项目综合能源系统规划方案进行了能量效率和效率计算,得出不同规划方案能源系统与系统子模块的能量效率和效率。研究结果表明,不同规划方案的能源系统能量效率为71%~93%,效率为34%~40%。对于包含电、冷、热不同形态能源的区域综合能源系统,分析方法是评价系统热效率较为有效的方法。     

火电机组热力系统成本分布通用矩阵方程

基于成本理论建立了热力系统局部成本分析通用模型及火电机组热力系统成本分布的通用矩阵方程,并对某600MW机组的热力系统进行实例计算与分析,得到了额定工况下独立流的单位成本.结果表明：该方程构造规范,适用于各种不同的热力系统,可以用于分析热力系统中存在的共性规律;对于具体的热力系统,通过将一些必要的矩阵元素代入方程中,可得到独立流的单位成本和单位成本的分布规律,为机组的节能降耗提供指导;如果对方程进行进一步的微分运算分析,还可求出一些因素变化对单位成本影响的敏感度.     

分析方法在电站锅炉中的应用

概述分析的基本原理及方法,建立电站锅炉分析模型;通过平衡分析方法能反映电站锅炉的外部损失如排烟、散热损失,并揭示能量转换过程的内部损失,即不可逆过程损失。以某220t/h燃煤锅炉为研究对象,其计算结果揭示了电站锅炉的各种损失及其部位,为火电厂进一步开展节能工作提供理论依据。     

基于单元(火用)分析模型回热系统节能诊断

电厂运行的经济性已经日显重要。回热系统作为电厂热力系统中的主要系统之一,它对全厂的经济运行产生着很大影响,因此,回热系统经济性分析是电厂节能工作中的重要部分。以某热电厂机组的回热系统为研究对象,给出了系统的单元划分方法和通用的单元分析控制体模型,导出了通用的性能评价指标计算式,以实际计算说明了基于单元分析模型的节能潜力诊断方法。该方法可以找出系统能量损失的关键部位,为电厂热力系统节能分析提供一条依据。     

内燃机冷热电联产系统设计点性能分析

简介内燃机冷热电联产系统的发展现状,总结了发电用内燃机在设计点工况下主要参数的现有分布范围:排气温度约为450~600℃,排气流量基本上与额定功率呈线性关系,发电效率一般在33%~45%。对联产系统不同形式的能量输出、联产系统经济效率等进行分析研究,表明联产系统回收的能量主要来自排气和冷却水,排气回收能量一般高于冷却水回收能量。与热电联产系统相比,由于制冷比供热困难,冷热电联产系统的经济效率较高。     

基于化学(?)的燃煤锅炉污染物排放及环境影响评价

化学作为评价系统对环境影响的客观参数,目前已经在不同的研究领域应用。通过建立烟气污染物SO_2、NO_x、CO_2等排放计算模型,分析某600 MW亚临界燃煤电站锅炉经济环保特性,绘制变负荷下不同气体的物理、化学及总的排放变化曲线。基于气体污染物的化学建立等价CO_2排放分析模型,评估气体污染物排放对环境的影响。研究结果表明:低负荷时,尤其SCR系统不能正常投运时NO浓度增加,NO的排放急剧增加,而高负荷时由于SCR、FGD等环保设备的投运对燃煤锅炉的环保性能改善明显;随着机组负荷的增加,单位发电量等价CO_2排放量降低,表明锅炉高负荷运行时具有良好的经济性和环保性能。     

小型热电站热电联产分析及节能评价

采用平衡分析法,分别对小型热电联产系统和分散锅炉房供热系统进行了流分析,把两者计算所得效率作一对比,从而得出热电联产系统是取代分散锅炉房供热的节能措施之一。同时还对热电联产系统内各环节中的流损失进行计算,得出各热力设备的效率,找出系统用能不合理的主要薄弱环节,为今后设备的工艺过程改进指出了方向。     

Energy,exergy and exergoeconomic analysis of a steam power plant: A case study

The objective of this paper is to perform the energy, exergy and exergoeconomic analysis for the Hamedan steam power plant. In the first part of the paper, the exergy destruction and exergy loss of each component of this power plant is estimated. Moreover, the effects of the load variations and ambient temperature are calculated in order to obtain a good insight into this analysis. The exergy efficiencies of the boiler, turbine, pump, heaters and the condenser are estimated at different ambient temperatures. The results show that energy losses have mainly occurred in the condenser where 306.9 MW is lost to the environment while only 67.63 MW has been lost from the boiler. Nevertheless, the irreversibility rate of the boiler is higher than the irreversibility rates of the other components. It is due to the fact that the combustion reaction and its high temperature are the most significant sources of exergy destruction in the boiler system, which can be reduced by preheating the combustion air and reducing the air–fuel ratio. When the ambient temperature is increased from 5 to 24°C, the irreversibility rate of the boiler, turbine, feed water heaters, pumps and the total irreversibility rate of the plant are increased. In addition, as the load varies from 125 to 250 MW (i.e. full load) the exergy efficiency of the boiler and turbine, condenser and heaters are increased due to the fact that the power plant is designed for the full load. In the second part of the paper, the exergoeconomic analysis is done for each component of the power plant in order to calculate the cost of exergy destruction. The results show that the boiler has the highest cost of exergy destruction. In addition, an optimization procedure is developed for that power plant. The results show that by considering the decision variables, the cost of exergy destruction and purchase can be decreased by almost 17.11%. Copyright © 2008 John Wiley & Sons, Ltd.     

Exergoeconomic analysis of a combined heat and power (CHP) system

This study deals with exergoeconomic analysis of a combined heat and power (CHP) system along its main components installed in Eskisehir City of Turkey. Quantitative exergy cost balance for each component and the whole CHP system is considered, while exergy cost generation within the system is determined. The exergetic efficiency of the CHP system is obtained to be 38.33% with 51 475.90 kW electrical power and the maximum exergy consumption between the components of the CHP system is found to be 51 878.82 kW in the combustion chamber. On the other hand, the exergoeconomic analysis results indicate that the unit exergy cost of electrical power produced by the CHP system accounts for 18.51 US$ GW^?1. This study demonstrates that exergoeconomic analysis can provide extra information than exergy analysis, and the results from exergoeconomic analysis provide cost‐based information, suggesting potential locations for the CHP system improvement. Copyright © 2007 John Wiley & Sons, Ltd.     

Energy and exergy analysis of a steam power plant in Jordan

In this study, the energy and exergy analysis of Al-Hussein power plant in Jordan is presented. The primary objectives of this paper are to analyze the system components separately and to identify and quantify the sites having largest energy and exergy losses. In addition, the effect of varying the reference environment state on this analysis will also be presented. The performance of the plant was estimated by a component-wise modeling and a detailed break-up of energy and exergy losses for the considered plant has been presented. Energy losses mainly occurred in the condenser where 134 MW is lost to the environment while only 13 MW was lost from the boiler system. The percentage ratio of the exergy destruction to the total exergy destruction was found to be maximum in the boiler system (77%) followed by the turbine (13%), and then the forced draft fan condenser (9%). In addition, the calculated thermal efficiency based on the lower heating value of fuel was 26% while the exergy efficiency of the power cycle was 25%. For a moderate change in the reference environment state temperature, no drastic change was noticed in the performance of major components and the main conclusion remained the same; the boiler is the major source of irreversibilities in the power plant. Chemical reaction is the most significant source of exergy destruction in a boiler system which can be reduced by preheating the combustion air and reducing the air–fuel ratio.     

Modified exergoeconomic modeling of geothermal power plants

In this study, a modified exergoeconomic model is proposed for geothermal power plants using exergy and cost accounting analyses, and a case study is in this regard presented for the Tuzla geothermal power plant system (Tuzla GPPS) in Turkey to illustrate an application of the currently modified exergoeconomic model. Tuzla GPPS has a total installed capacity of 7.5 MW and was recently put into operation. Electricity is generated using a binary cycle. In the analysis, the actual system data are used to assess the power plant system performance through both energy and exergy efficiencies, exergy losses and loss cost rates. Exergy efficiency values vary between 35% and 49% with an average exergy efficiency of 45.2%. The relations between the capital costs and the exergetic loss/destruction for the system components are studied. Six new exergetic cost parameters, e.g., the component annualized cost rate, exergy balance cost, overall unavoidable system exergy destruction/loss cost rate, overall unavoidable system exergy destruction/loss cost rate, overall unavoidable system exergy production cost rate and the overall unavoidable system exergy production cost rate are studied to provide a more comprehensive evaluation of the system.     

基于结构理论的350MW超临界直接空冷机组的热经济学分析

应用结构理论建立了某超临界直接空冷机组的热经济学模型,通过量化各组件间的生产交互关系、计算各组件的单位成本,分析了系统生产成本的形成过程.简化合并直接空冷机组的凝汽组件,并近似计算其耗电量.根据该机组THA工况的计算结果,分析了影响组件产品单位成本的因素.结果表明:当消耗同一种燃料时,组件效率越低,其产品单位成本就越高;当消耗不同燃料时,要综合考虑燃料成本和效率对产品单位成本的影响,并指出7号低压加热器、给水泵、小汽轮机以及凝结水泵等组件的单位成本较大;直接空冷机组凝汽器的单位成本显著高于湿冷机组,应用结构理论能够准确评价空冷机组的生产性能.     

火电机组的热经济性分析

为进行整个火电机组的能量系统热经济性分析及考察其组元变化的影响，提出了以热经济学和边际成本概念为基础的热经济性分析方法。对复杂能量系统主要以功能划分后形成的组元，考察其组元的输出炯流变化引起整个系统的能耗变化，可以通过边际炯成本、单位炯成本和组元产品的函数来表达，来衡量整个系统所有组元的输出炯流变化对系统外部输入燃料的影响，便于火电机组的运行经济状态动态评估。通过300MW机组主蒸汽参数变化的计算表明：参数变化时将引起系统的煤耗增加，降低了经济性，因而从本质上进行了热经济性的全面综合分析，以优化机组运行，进行性能诊断。图1表2参10     

Conventional and advanced exergoeconomic assessments of a CCHP and MED system based on solid oxide fuel cell and micro gas turbine

This paper presents an assessment of a combined cooling, heating and power (CCHP) and multi-effect desalination (MED) system based on SOFC/MGT by conventional and advanced exergoeconomic analyses. The conventional exergy analysis can reveal the sources of irreversibility in the system. The largest exergy destruction occurs in after burner followed by SOFC and MED, accounting for 20.079%, 12.986%, 12.907%, respectively. In the advanced analysis, the exergy destruction, exergy destruction cost and investment cost are split into avoidable/unavoidable and endogenous/exogenous parts to investigate the real potentials of exergy and economic performances. The advanced analysis results indicate that the major exergy destructions of most components are endogenous parts with inverter, MGT and air compressor owning the most potentials to reduce exergy destructions. The modified exergy efficiency of each component in the advanced analysis is higher than the conventional one. Finally, three possible strategies are suggested to reduce the avoidable exergy destruction cost rates.     

基于火用分析的水体热污染评价方法

将火用分析与水体热污染结合在一起,从火用分析角度阐述了水体热污染的概念,并建立了水体热污染的火用分析模型,给出了温排水和水环境生态系统火用的计算公式,在此基础上,定义了水体热污染率,并运用于水体热污染评价上。以美国某电厂温排水为例,根据火用分析法计算了水体热污染率。结果表明,火用分析能够定量和统一地评价水体热污染程度,与其他评价方法相比,该方法能更加直观地评判水体热污染状况,为水体热污染控制和水资源开发利用提供了科学决策依据。     

A new thermoeconomic methodology for energy systems

Thermoeconomics, or exergoeconomics, can be classified into the three fields: cost allocation, cost optimization, and cost analysis. In this study, a new thermoeconomic methodology for energy systems is proposed in the three fields. The proposed methodology is very simple and clear. That is, the number of the proposed equation is only one in each field, and it is developed with a wonergy newly introduced in this paper. The wonergy is defined as an energy that can equally evaluate the worth of each product. Any energy, including enthalpy or exergy, can be applied to the wonergy and be evaluated by this equation. In order to confirm its validity, the CGAM problem and various cogenerations were analyzed. Seven sorts of energy, including enthalpy and exergy, were applied for cost allocation. Enthalpy, exergy, and profit were applied for cost optimization. Enthalpy and exergy were applied for cost analysis. Exergy is generally recognized as the most reasonable criterion in exergoeconomics. By the proposed methodology, however, exergy is the most reasonable in cost allocation and cost analysis, and all of exergy, enthalpy, and profit are reasonable in cost optimization. Therefore, we conclude that various forms of wonergy should be applied to the analysis of thermoeconomics.