1000MW火电机组热力系统改进热经济性分析

为了提高火电厂的发电热效率,降低冷端余热热污染,应对火电厂中的汽轮机乏汽热量进行回收利用.现在以N1030-26.25/600/600为例:对该机组热力循环系统进行改进,加入有机工质循环;利用其自身的热力特性,使有机工质吸收机组凝汽器中水蒸汽中的汽化潜热;成为有一定压力和温度的过热蒸汽,再进入低压缸做功.经过热经济性计算,结果显示:在THA、75％ THA、50％ THA工况下,采用甲苯、R365MFC、正戊烷3种有机工质,在机组总热耗、机组排汽温度与原机组相同的情况下,新系统的冷端热量减少,发电热效率得到了提高;采用新系统可以使机组热经济性提高;其中工质R365MFC环保性好,发电热效率高,排汽压力合适,为新系统最适合的有机工质.     

燃气-蒸汽-有机工质联合循环发电工艺

基于梯级利用方法,提出了燃气-蒸汽-有机工质联合循环发电工艺,建立了理论耦合计算模型,并以北京太阳宫燃气热电有限公司350MW机组的设计和运行工况参数为基础,对研发的新工艺与太阳宫原工艺进行热经济性对比分析。计算表明:依据正能量系数,优选R141b工质的设计工况下,燃气-蒸汽-有机工质联合循环新工艺发电功率达800.1MW,发电效率达59.1%;运行工况下,新工艺发电功率达566.65MW,发电效率达54.51%,设计工况下分别比太阳宫原工艺提高了20.1MW和1.48%;运行工况下分别提高了15.45MW和1.45%。     

燃气分布式能源在某医院中的应用分析

燃气分布式能源系统作为一种新的能源供应方式,在提高能源综合利用效率的同时减少污染物排放。医院能源负荷种类较多,能源使用时间较长,适合采用燃气分布式能源系统。在为医院设计燃气分布式能源系统时需根据医院实际负荷选择合理的机组和方案,确保燃气分布式能源系统能够达到合理的运行时间,保证运行经济性。以无锡某新建医院为例,基于医院实际负荷配置了合理的燃气分布式能源系统,与常规能源系统进行比对,得出采用燃气分布式能源系统可以降低医院的用能成本,具有一定的经济性。     

Thermal Economy Analysis of Steam-Organic Fluid Combined Cycle Power Generation Model Based on Different Working Fluids

以NZK660-24.2/566/566机组为例,建立了可减少汽轮机冷源热量、增加发电量的蒸汽-有机工质联合循环发电模型.为了筛选出适合新模型的工质,根据工质性质设定新模型的运行参数,通过采用排汽温度为55.3℃及35℃的原机组及新模型的热经济性指标对9种有机工质的热力性能进行了分析.结果表明：与原机组在排汽温度为35℃时相比,当机组热耗相同时,新模型的发电热效率提高,不同工质的发电效率提高幅度不同,而且空冷面积变小;随着工质临界温度的升高,低压缸2的进口压力和排汽压力呈下降趋势;新模型采用环保工质R365MFC时,低压缸2的进、出口压力较为适宜,且排汽未通过湿蒸汽区,可获得较高的热效率.     

天然气分布式供能系统在上海城市中心商务区的适用性

通过分析上海城市中心商务区冷、热负荷特点,建立了区域天然气分布式供能系统模型,并分析了其经济性和节能效益,最终得出以燃气内燃机为主动力源的天然气分布式供能系统不是很适用于城市中心商务区的结论。     

基于ZK1200国产燃气轮机的工业分布式 供能系统的经济性分析

本文以采用ZK1200国产燃气轮机的苏州蓝天燃气热电有限公司金鸡湖项目的工业分布式供能系统为研究对象,利用商业NPSS软件,通过现场采集实际用能数据、建立并修正模型和计算实时收益对系统经济性进行分析,并针对三种运行模式下的经济性作出对比,最终提出优化运营策略,为机组的运行提供了参考。     

高铁客运站分布式多能源系统供能协同优化策略研究

为解决传统高铁客运站供能系统中能源利用率较低的问题,以日运行购气费用和购电费用最优为优化目标,以系统运行过程中实时能量平衡为约束条件,以可再生能源出力和吸收式制冷占比为优化变量,建立多能源协同供能的分布式能源系统,并将该模型应用于北方某高铁客运站,分析可再生能源的利用率、制冷系统中可再生能源电出力的电制冷占比以及电网出力的节电率。仿真计算结果表明,分布式能源系统的使用提高了可再生能源的利用率,其中风电机组出力占其出力极限的96.5%,光伏机组出力94.7%;相比于参比系统,分布式能源系统的成本节约率为12.5%;电制冷占比为13%;电网的节电率为53.9%。     

ISCC分布式能源站的系统设计与初步分析

基于分布式能源和太阳能联合循环发电(integrated solar combined cycle power generation,ISCC)技术,以某高新科技产业园区域为例,提出一种利用太阳能直接蒸汽系统与燃气-蒸汽联合循环耦合的新型ISCC分布式能源系统,对该系统组成及工作原理进行介绍,并计算出匹配的太阳能集热场面积和发电机容量。对该ISCC分布式能源系统的性能分析结果表明,ISCC分布式能源站与常规的燃气-蒸汽联合循环电站相比可减少燃料消耗2.2%。另外,多种能源供应模式不仅使系统运行更加稳定,而且能有效提高系统的效率。     

塔式太阳能与燃煤互补复合发电系统技术经济性分析

提出塔式太阳能与燃煤机组复合发电系统的优化集成方案,建立复合发电系统技术经济性评价的分析计算模型,以330 MW机组为例,对3种集成方案的技术经济性进行模拟计算。结果表明,塔式太阳能与燃煤机组复合发电系统的热功转换效率高于纯塔式太阳能低于燃煤机组,通过单方案判断、多方案比选和财务盈利能力的分析得出,塔式太阳能产生的蒸汽引入燃煤机组主蒸汽是较理想的选择,其热功转换效率约为42.8%,太阳能净发电成本为2.68$/k Wh。     

区域分布式能源系统的运行优化研究

随着社会用能需求的不断增加,对能源的清洁环保要求也不断提高。分布式冷热电三联供系统作为能源互联网中的重要组成部分,因其较高的能源综合利用效率、良好的节能性和经济性等优点在各地推广落地。通过分析上海某旅游度假区的燃气分布式冷热电三联供系统,统筹考虑系统的经济性和节能性,建立数学模型。采用遗传算法求解夏季、冬季、过渡季下的运行优化策略,对提高全国各地区三联供系统运行策略的节能性和经济性有借鉴指导意义,对分布式能源系统在各地区的推进发展具有促进作用。     

联合太阳能沼气的冷热电供能系统的集成及经济性分析

冷热电联供是一种先进、高效的能源系统,目前在我国应用的主要问题是天然气成本高,导致系统经济性差。太阳能和沼气是非常清洁的可再生能源,在我国来源广泛且廉价。将冷热电联供系统与太阳能、沼气完美地结合起来,集成为联合太阳能沼气的冷热电供能系统。该系统较为合理的组合方式是采用太阳能沼气池作为燃料提供装置,采用微型燃气轮机、余热锅炉、溴化锂吸收式制冷机、蒸汽换热器等作为供电、供冷和供热机组,采用太阳能集热器、换热器等装置为沼气池加热,太阳能不足时采用尾气加热。该系统能够实现能量的梯级利用,提高一次能源利用率,达到综合用能的目的,同时可有效治理环境。以某酒店作为该系统的用户对象,分析其经济性并与常规模式进行对比。结果表明,该系统一次能源利用率为74.8%,而常规模式为62.3%;综合能源价格为0.3398元/(k W·h),而现阶段电网电价约为0.6元/(k W·h);环境与减排评价指标也具有明显优势。     

Performance of S-CO_2 Brayton Cycle and Organic Rankine Cycle(ORC) Combined System Considering the Diurnal Distribution of Solar Radiation

This paper researches the performance of a novel supercritical carbon dioxide(S-CO_2) Brayton cycle and organic Rankine cycle(ORC) combined system with a theoretical solar radiation diurnal distribution. The new system supplies all solar energy to a S-CO_2 Brayton cycle heater, where heat releasing from the S-CO_2 cooler is stored in the thermal storage system which is supplied to the ORC. Therefore, solar energy is kept at a high temperature, while at the same time the thermal storage system temperature is low. This paper builds a simple solar radiation diurnal distribution model. The maximum continuous working time, mass of thermal storage material, and parameter variations of the two cycles are simulated with the solar radiation diurnal distribution model. 10 organic fluids and 5 representative thermal storage materials are compared in this paper, with the mass and volume of these materials being shown. The longer the continuous working time is, the lower the system thermal efficiency is. The maximum continuous working time can reach 19.1 hours if the system provides a constant power output. At the same time, the system efficiency can be kept above 38% for most fluids.     

基于太阳能及生物质能综合利用的分布式能源系统探讨

结合中国西部的能源现状及地域资源优势,提出一种新型的太阳能及生物质能综合利用的分布式能源系统,该系统主要由供电系统、供热系统、供气系统构成,形成一种高效无污染可以供沼气、供热、供电、提供农业生产肥料等能量梯级利用的综合供能系统.通过该系统模型的建立,探讨了该系统的可行性以及在可再生能源利用及环保节能等方面将起到的积极推动作用.     

冷却剂流量对聚光型太阳能光伏系统效率的影响

针对聚光型太阳能光伏电池工作中温度升高会导致发电效率降低的问题,在太阳能模组上铺设有机工质循环管路对光伏电池进行冷却,通过冷凝器对管内有机工质吸收的热量进行收集利用,构建聚光型太阳能光伏/光热综合利用系统。建立传热模型,计算不同日照强度下模组的输出效率并与实验数据进行对比。实验结果表明:发电效率随日照强度的增加先增加后减小;对光伏电池进行冷却可提升系统输出效率;太阳能光伏发电及散热量利用效率合计可达60%。     

新型城市低温地热冷热电联产系统热力性能分析

为节约及合理利用能源,提高城市能量总能系统利用率,基于有机朗肯循环(ORC)和冷热电联产(CCHP),提出了一种新型的城市低温地热冷热电联产系统(以下简称ORC-CCHP系统)。根据热力学第一、第二定律,建立了热力学模型,编写计算机程序进行了系统的热力性能分析。结果表明:采用R245fa、LiBr溶液作为ORCCCHP系统循环工质时,选择窄点温差较小蒸发器可获得更高火用效率;增加太阳能集/蓄热系统,提高热流参数,减小换热温差,可进一步提升系统热力学性能;系统分别采用5种不同有机工质时,R236fa使系统的热力性能达到最佳,并在蒸发压力为0. 62 MPa、窄点温差为0 K时,ORC-CCHP系统获得最大净输出功为1 948 kW,系统火用效率为19. 28%,系统火用效率最高值为85. 78%。     

Design and optimization of hybrid solar-hydrogen generation system using TRNSYS

Solar thermal systems are an efficient utilization of solar energy for hot water and space heating at domestic level. A Solar Water Heater (SWH) incorporating an Evacuated Glass Tube Collector (EGTC) is simulated using TRNSYS software. Efficiency parameters are pointed, and a parametric optimization method is adopted to design the system with maximum conceivable efficiency. In the first part, the selection of refrigerant for heat transportation in SWH loop is presented. A set of 15 working fluids are chosen, and their chemical properties are computed using NIST standard software (REFPROP). The selected working fluids are tested in the system under study and plots for energy gain and temperature are plotted using TRNSYS. Results showed that ammonia (NH₃) having specific heat 4.6kJ/kg-K and fluid thermal conductivity 2.12 kJ/hr-m supplies peak energy gain of 7500 kJ/h in winter and 8900 kJ/h in summer season along 120 °C temperature rise. On the other hand, R-123 having specific heat 0.65kJ/kg-K and fluid thermal conductivity 0.0293kJ/hr-m showed inferior performance during the simulation. A solar-hydrogen co-generation system is also designed and simulated under low solar insolation and warm climate regions to study annual hydrogen produced by the hybrid system. System comprises main components: a PV array, an electrolyzer, a fuel cell, a battery, a hydrogen storage unit and a controller in the complete loop. Results of Hydrogen cogeneration system provide 7.8% efficiency in the cold climate of Fargo North Dakota state due to lower solar insolation. While hot climate condition of Lahore weather provides efficiency of 11.8% which satisfy the statistics found in literature.     

Experimental study on the performance of solar Rankine system using supercritical CO2

An experimental study is carried out to investigate the performance of a solar Rankine system using supercritical CO₂ as a working fluid. The testing machine of the solar Rankine system consists of an evacuated solar collector, a pressure relief valve, heat exchangers and CO₂ feed pump, etc. The solar energy powered system can provide electricity output as well as heat supply/refrigeration, etc. The system performance is evaluated based on daily, monthly and yearly experiment data. The results obtained show that heat collection efficiency for the CO₂-based solar collector is measured at 65.0–70.0%. The power generation efficiency is found at 8.78–9.45%, which is higher than the value 8.20% of a solar cell. The result presents a potential future for the solar powered CO₂ Rankine system to be used as distributed energy supply system for buildings or others.     

Energy and exergy analyses of an ice-on-coil thermal energy storage system

In this study, energy and exergy analyses are carried out for the charging period of an ice-on-coil thermal energy storage system. The present model is developed using a thermal resistance network technique. First, the time-dependent variations of the predicted total stored energy, mass of ice, and outlet temperature of the heat transfer fluid from a storage tank are compared with the experimental data. Afterward, performance of an ice-on-coil type latent heat thermal energy storage system is investigated for several working and design parameters. The results of a comparative study are presented in terms of the variations of the heat transfer rate, total stored energy, dimensionless energetic/exergetic effectiveness and energy/exergy efficiency. The results indicate that working and design parameters of the ice-on-coil thermal storage tank should be determined by considering both energetic and exergetic behavior of the system. For the current parameters, storage capacity and energy efficiency of the system increases with decreasing the inlet temperature of the heat transfer fluid and increasing the length of the tube. Besides, the exergy efficiency increases with increasing the inlet temperature of the heat transfer fluid and increasing the length of the tube.     

建筑节能新方向:太阳能光伏-地源热泵系统

减少我国冬季采暖所造成的大气污染,降低供暖系统的能耗,节约能源一直是建筑节能追求的目标.目前太阳能光伏发电已经成为人类利用太阳能的最主要方式之一,地源热泵已被作为一项旨在解决建筑冷热源问题的新技术,日渐受到人们的重视.将光伏转换与热泵循环有机结合在一起,从而形成了太阳能光伏-地源热泵系统.该系统提高了光电转换和光热吸收效率,光电/光热综合利用,极大地提高了单位面积太阳辐照的利用效率,同时可提高热泵系统在寒冷地区运行的适用性;利用光电效应把太阳能中高能带区域的光能直接转化成电能,可大大提高太阳能的可用能效率;在增加能量储存装置和逆变器的条件下,可以使系统脱离公用电网运行,从而增加了系统的适用性和灵活性;与普通的空气源热泵相比,太阳能地源热泵具有较高的热性能,具有一机多用的功效;与建筑物相结合的太阳能热泵系统,可以增加建筑物的隔热效果,起到减少建筑物冷暖负荷的作用,同时可极大地减少环境污染.     

Investigation of evacuated tube heated by solar trough concentrating system

Two types of solar evacuated tube have been used to measure their heating efficiency and temperature with fluids of water and N₂ respectively with a parabolic trough concentrator. Experiments demonstrate that both evacuated tubes present a good heat transfer with the fluid of water, the heating efficiency is about 70–80%, and the water is easy to boil when liquid rate is less than 0.0046 kg/s. However, the efficiency of solar concentrating system with evacuated tube for heating N₂ gas is less than 40% when the temperature of N₂ gas reaches 320–460 °C. A model for evacuated tube heated by solar trough concentrating system has been built in order to further analyze the characteristics of fluid which flow evacuated tube. It is found that the model agrees with the experiments to within 5.2% accuracy. The characteristics of fluid via evacuated tube heated by solar concentrated system are analyzed under the varying conditions of solar radiation and trough aperture area. This study supports research work on using a solar trough concentrating system to perform ammonia thermo-chemical energy storage for 24 h power generation. The current research work also has application to solar refrigeration.