Evaporative Cooling Applied in Thermal Power Plants:A Review of the State-ofthe-Art and Typical Case Studies

A review is conducted about the application of the evaporative cooling technology in thermal power plants.Different case studies are considered,namely,evaporative air conditioners,evaporative cooling in direct air-cooled systems,gas turbine inlet cooling,wet cooling towers,and hybrid cooling towers with a crosswind effect.Some effort is provided to describe the advantages related to direct evaporative cooling when it is applied in thermal power plants and illustrate the research gaps,which have not been filled yet.In particular,typical case studies are intentionally used to compare the cooling performances when direct evaporative cooling is implemented in different types of cooling towers,including the natural draft wet cooling tower(NDWCT)and the pre-cooled natural draft dry cooling tower(NDDCT).It is shown that the NDWCT provides the best cooling performance in terms of power station cooling,followed by the pre-cooled NDDCT,and the NDDCT;moreover,the evaporative pre-cooling is able to enhance the cooling performance of NDDCT.Besides,on a yearly basis,better NDDCT cooling performances can be obtained by means of a spray-based pre-cooling approach with respect to wet media pre-cooling.Therefore,the use of nozzle spray is suggested for improvement in the performance of indirect/direct air-cooling systems with controlled water consumption.

Measuring Environmental Performance of Provincial Thermal Power Plants in China:A Malmquist DEA Approach with Fixed-Sum Undesirable Outputs

With the development of China’s economy,environmental pollution has become cumulatively serious.The primary source of environmental pollution is thermal power generation,which has attracted the attention of governments and academia in recent years.To effectively reduce environmental pollution,research should study how to constrain the undesirable output of thermal power plants,that is,to limit the total undesirable output of the plants to a certain fixed sum.However,few studies have suggested that these undesirable outputs should be fixed-sum outputs.Moreover,no previous research publication about thermal power plants has analyzed their environmental performance changes.To address these gaps,a novel Malmquist-DEA approach is proposed for evaluate the environmental performance of thermal power plants in this paper.This approach generalizes the equilibrium efficient frontier DEA model with fixed-sum undesirable outputs and incorporates the model into the Malmquist productivity index(MPI).The authors apply this approach to the analysis of provincial thermal power plant environmental performance in China and analyze such plants’trends based on panel data from2011 to 2014.The empirical research shows that the environmental performance of regional thermal power plants was positively affected by efficiency change and negatively affected by technical change.Finally,the authors provide policy suggestions based on our findings.

Thermo-Dynamical Analysis on Electricity-Generation Subsystem of CAES Power Plant

Besides pumped hydropower, Compressed Air Energy Storage (CAES) is the other solution for large energy storage capacity. It can balance fluctuations in supply and demand of electricity. CAES is essential part of smart power grids. Linked with the flow structure and dynamic characteristic of electricity generation subsystem and its components, a simulation model is proposed. Thermo-dynamical performance on off-design conditions have been analyzed with constant air mass flux and constant gas combustion temperature. Some simulation diagrams of curve are plotted too. The contrast of varied operation mode thermal performance is made between CAES power plant and simple gas turbine power plant.

A case study of digital-twin-modelling analysis on power-plant-performance optimizations

China Energy’s National Institute of Clean-and-Low-Carbon Energy(NICE)is developing a Power Plant Smart Management(PPSM)platform that employs digital-twin technology to undertake techno-economic modelling analysis on China Energy’s existing coal-fired power-plant units and explore cost-effective solutions to improve those plant units’thermal efficiencies and operating performance.This paper presents a case study of PPSM on a 320-MWe coal-fired thermal power-plant unit,demonstrating how the digital-twin technology was employed to explore and analyse optimization solutions.Various optimization solutions and their cost-effectiveness were assessed using the digital-twin-modelling analysis;the results indicated the optimization solutions are expected to improve the plant unit’s operating efficiency and reduce its current electricity-generation coal consumption by up to 3.5 g/kWh standard coal equivalent(sce),worth annual fuel-cost savings of approximately 4 million RMB for a single unit or 8 million RMB for the two identical 320-MWe units that the power plant currently operates.The digital twin was also employed to assess the power-plant unit’s operating economics during both summer and winter.In summer,when the unit operates in electricity-generation-only mode,the unit’s operating thermal efficiency could drop by up to 6%points following the grid demand of load changes from 100%maximum continuous rating(MCR)down to 30% MCR,resulting in an~45 RMB/MWh increase of electricity-generation cost.In winter,when the unit operates in combined heat and power(CHP)cogeneration mode,for the same boiler load,the CHP operation increases the plant unit’s operating profit with increasing district-heating duty,although the relative profit gain from the CHP cogeneration could start to decrease when the district-heating steam-extraction flow increases to a certain point that varies depending on the market prices of heat and electricity,while the fuel cost was found to be equivalent to~50% of the unit’s total CHP income cogenerated from its electricity and district heat outputs.

火-储耦合系统深度调峰综合经济性分析

火电机组耦合储热技术,可提高机组的热电解耦能力,减少深度调峰对系统安全性和经济性的影响。本工作提出了火电机组与填充床储热的耦合系统,在考虑了机组变工况、填充床储/释热过程动态时间序列基础上,通过EBSILON建立了耦合系统变工况仿真模型;分析深度调峰对耦合系统热力性和碳排放量的影响,通过汽水分离器筒体应力变化分析深调对锅炉寿命损耗的影响,通过转子寿命损耗率曲线分析深调对汽轮机寿命的影响,最终建立耦合系统调度运行经济性模型,开展综合经济性分析。结果表明:火-储耦合系统比自身变工况减小碳排放量7418 t/a(仅配置风电)~9216 t/a(仅配置光伏);深度调峰对锅炉寿命损耗的影响大于汽轮机,火-储耦合系统可提高系统运行寿命,深度调峰318次/年,相比于机组自身变工况(30%~20%额定负荷)可提高13.3%~15.3%;火-储耦合系统深度调峰收益高于火电机组自身变工况,当填充床释热量用于发电或供热时,耦合系统比自身变工况收益分别增加40万元/年、72万元/年。

煤电机组耦合储热系统的灵活性调峰特性研究及其性能评价

“双碳目标”背景下,煤电机组将长期作为主力调峰电源,保障电网安全稳定。储热是提升煤电机组灵活性的重要手段,但煤电耦合储热系统的运行特性尚不明确,不同储热技术与煤电机组耦合适应性亟待研究。为此,该文构建600 MW煤电-90 MW显热/潜热/热化学储热3种耦合系统,详细考察系统储/释热过程调峰能力及热力学性能,并基于优劣解距离法(technique for order preference by similarity to an ideal solution,TOPSIS)综合评价,明确最优耦合方案。研究发现,储热过程,Ca(OH)_(2)/CaO热化学储热的调峰容量、调峰深度及?效率均优于热水及熔融盐储热,而释热过程熔融盐储热性能最优;通过TOPSIS综合评价法确定热储热方案均为抽取主蒸汽作为热源,最佳释热方案均为以#2高加进水为冷源,同时确定煤电耦合熔融盐储热为最佳系统耦合方案。相关研究结论可为构建煤电耦合储热调峰系统提供一定的理论和数据支撑。

Research on solar aided coal-fired power generation system and performance analysis

Integrating solar power utilization systems with coal-fired power units, the solar aided coal-fired power generation (SACPG) shows a significant prospect for the large-scale utilization of solar energy and energy saving of thermal power units. The methods and mechanism of system integration were studied. The parabolic trough solar collectors were used to collect solar energy and the integration scheme of SACPG system was determined considering the matching of working fluid flows and energy flows. The thermodynamic characteristics of solar thermal power generation and their effects on the performance of thermal power units were studied, and based on this the integration and optimization model of system structure and parameters were built up. The integration rules and coupling mecha- nism of SACPG systems were summarized in accordance with simulation results. The economic analysis of this SACPG system showed that the solar LEC of a typical SACPG system, considering CO2 avoidance, is 0.098 $/kW·h, lower than that of SEGS, 0.14 $/kW·h.

掺烧绿氢对联合循环发电系统热力性能影响研究

随着我国电力产业从化石能源向清洁低碳能源转变,考虑提高可再生能源在电力系统中的占比对推动能源消费革命具有重要意义。研究了燃气-蒸汽联合循环发电机组掺烧绿氢对系统热力性能的影响。分析了H 2掺混比例从10%提高到50%过程中,所需燃料的质量流量、燃机的排烟参数、燃气轮机和汽轮机的出力以及系统在不同工况下的年CO_(2)减排量的变化。研究结果表明,随着H_(2)掺混比例的提高,燃汽轮机的排烟温度从593.3℃升高到623.19℃,燃气流量从653.9 kg/s下降到592.4 kg/s,汽轮机出力提高了0.15%,而燃气轮机的出力降低。此外,当H 2掺混比例为50%以及在满负荷工况下,系统年CO_(2)减排量为26.64×10^(4)t。

电厂汽轮机组的脱碳热耦合变工况模拟及汽耗特性

燃煤电厂采用醇胺法碳捕集会降低电厂汽轮机组的发电功率及发电效率,也会使汽轮机组汽耗特性曲线与设计曲线相比发生变化,因此需要变工况模拟脱碳热耦合对汽轮机组性能的影响,并重新绘制脱碳汽轮机组的汽耗特性曲线。文中采用模拟准确度更高的变流量变压力方法,模拟了脱碳热耦合对锦界电厂汽轮机组的影响,并将模拟结果与目前研究中常用的变流量定压力方法模拟结果进行对比分析。在此基础上,针对目前缺乏相关脱碳汽轮机组汽耗特性关系研究的问题,提出采用变流量变压力方法研究脱碳汽轮机组的汽耗特性关系,绘制汽耗特性曲线,为脱碳汽轮机组的运行调节提供依据,填补相关研究空白。模拟结果表明,当二氧化碳捕集规模为15万t/a时,变流量变压力模拟得到的脱碳汽轮机组发电功率与变流量定压力模拟结果相比高22 kW,相差0.04%,2种模拟方法的模拟结果相差不大;当锦界电厂600 MW机组的锅炉烟气CO_(2)全部捕集(捕集规模为360万t/a),变流量变压力模拟得到的脱碳汽轮机组发电功率与变流量定压力模拟结果相比高33.7 MW,相差5.61%。汽耗特性研究结果表明,随碳捕集规模增加,脱碳热耦合机组发电功率减小,机组汽耗特性变动率逐渐增大。当碳捕集规模分别为烟气CO_(2)捕集率为4%(年捕集量15万t)、捕集率60%、捕集率80%以及烟气CO_(2)全部捕集时,脱碳汽轮机组的汽耗特性曲线变动最大值分别为1.3%、11.85%、12.6%及13.2%。

基于LSSVM的火力发电厂燃煤发电机组碳排放测算方法

为解决燃煤发电机组在投产使用后存在的碳排放过大等问题,降低机组运行对大气环境的负面影响,作者以某火力发电厂为例,引入最小二乘支持向量机(LSSVM),开展燃煤发电机组碳排放测算方法的设计研究。以LSSVM中的径向基(RBF)函数核,构建燃煤发电机组碳排放相关数据样本集合,根据样本集合容量,进行数据的非线性映射,实现对发电机组碳排放相关数据的筛查;建立火力发电厂碳排放强度计算模型,对火力发电厂燃煤发电机组在运行过程中煤耗综合情况进行系统化分析。考虑到火力发电厂燃煤发电机组在投产使用后会不可避免地存在损耗,在碳排放强度已知的情况下,对考虑网损的发电机组碳排放进行测算。实验结果表明:设计的测算方法应用效果良好,规范使用该方法进行火力发电厂燃煤发电机组碳排放测算,测算结果更加贴合实际。

发电厂热能与动力工程问题及其主要性能的应用分析

热力学是现代产业发展的基石,它能够推动产业发展,提升产业的效益与品质。电力工程作为支撑经济发展的基础,在节能和提高输出效率方面已成为业界最关心的问题。随着科学技术的发展,我国的发电方式已经从单一转向多样化。在发电厂中引入热力学,能够提高发电厂的安全生产水平,为发电厂带来效益。这既是当前发电厂工作的主要目的,也是发电厂的发展方向。为此,有必要对热力学在发电厂中的运用进行研究,以提高其运用层次。

热力发电厂在乏汽回收利用过程中的冷源损失分析

随着节能减排工作的深入推进,各热电企业开始积极回收利用各种乏汽,其中比较典型的乏汽回收方式有热力除氧器乏汽回收和锅炉定排扩容器乏汽回收。但部分企业在计算抽汽回热式汽轮发电机组乏汽余热回收效益时,只是简单地将回收的热量折合成标煤计算,未考虑冷源损失,从而造成了较大的误差。通过对具体乏汽回收案例计算过程的分析和纠正,说明了热力发电厂需结合自身工艺流程将汽轮机做功过程中的冷源损失从乏汽回收效益中去除,以确保回收效益计算的准确性。

SCR脱硝精准喷氨技术在火电厂中的应用与性能分析

近年来,随着环境保护意识的不断增强与排放标准的日益严格,火电厂作为主要的能源供应来源,面临着减少大气污染物排放的重要任务。其中,氮氧化物(NO_(x))是火电厂燃烧过程中主要的污染物之一,对大气质量和人体健康造成了严重威胁。为了降低火电厂的NO_(x)排放量,SCR脱硝技术被广泛应用于火电厂。SCR脱硝技术以其高效、可靠的特点,成为当前减少NO_(x)排放的主流技术之一。而其中的精准喷氨技术则是SCR脱硝技术的关键环节,SCR脱硝技术的有效应用具有重要意义。本文将重点对SCR脱硝精准喷氨技术在火电厂中的应用与性能进行深入分析。

火力发电厂回转式空气预热器性能改造研究

文章系统分析预热器运行现状,针对换热效率低、漏风量大等关键问题,提出创新的综合改造方案。该方案包括应用新型密封技术、优化换热元件以及使用高频声波吹灰装置等措施。通过对某电厂机组预热器的实验改造,评估方案的实际效果。实验结果表明,改造后预热器的热效率显著提高,漏风率大幅降低,换热端温差明显减小,比热耗和热损失均得到改善,说明所提出的改造方案可以显著提升回转式空气预热器的性能。

基于闭环运行数据的火电厂控制信息安全保护性能评估方法研究

为准确揭示火电厂控制系统的安全保护性能,保障电力生产的持续稳定运行,利用闭环运行数据,开展了火电厂控制信息安全保护性能评估方法研究。首先,采集火电厂闭环运行数据,并对其进行去噪处理,提供数据支持;其次,结合火电厂控制系统实际情况,识别控制信息可能面临的安全威胁;在此基础上,分析各风险评估要素间的关系,量化评估控制信息安全风险,得出风险等级、风险严重性及处理优先级。结果表明,该方法应用后,各项性能的评估评分与实际安全保护性能结果的评分最接近,在评估火电厂控制信息安全保护性能时具有较高的准确性。

基于粒子群算法的火力发电厂粉煤灰高性能混凝土配合比优化

当前火力发电厂粉煤灰混凝土配合比计算常基于单一环境,文章提出基于粒子群算法的粉煤灰高性能混凝土配合比优化方案,明确材料基础掺量,增强多环境计算的可靠性,构建优化模型,采用抗渗测定优化配合比。实验结果表明,经过三个配合比优化阶段的测定,测试构件的抗压强度均可以达到30 MPa以上,说明在粒子群算法的辅助下,优化方法的针对性更高。

电厂热力系统矩阵分析法的改进

在分析电厂热力系统热平衡串联解法特点的基础上，给出了完整的矩阵表达的热平衡方程式，并指出其中各项与系统结构的对应关系。把电厂热力系统视为与辅助汽水系统的叠加，这种叠加在数学上表现为热平衡矩阵式中的各矩阵项之和。

电力生产环境成本计算方法的研究

对电力生产的环境成本进行了研究,建立了适合我国国情的包括9种发电方式的电力生产环境成本计算模型,并以贵阳电厂为例进行了分析。该模型可根据电厂的实际情况,采用常规数据计算电厂发电的环境成本。计算结果表明,在我国人口众多的东部地区,环境成本最大的是燃煤发电,为21.76分/(kW.h);环境成本最小的是风力发电,成本为0.60分/(kW.h)。

火力发电企业CO_2排放量和减排分析

分析了电力企业CO2排放量的计算模式,提出IPCC排放因子计算模式、实测方法、物料衡算方法和宏观模型方法,并就影响排放因子的因素进行校核,提出电力生产低碳发展静脉循环经济模式下的捕获和资源化应用CCU减排思路.

大型热力发电机组能耗参数的统计分析与应用

基于机组长期运行数据和在线性能计算数据,统计分析了机组的实际性能特性,提出与过程热力特性及热力试验标准相一致的机组性能稳定态判别准则。由筛选出的满足稳定态准则的数据统计分析分别得出了机组在不同的外界边界条件和不同运行参数下以及同一运行工况内在线性能计算模型输出的不确定度范围,为基于模型的优化决策调整和诊断提供参考。统计得出的热力机组煤耗量特性曲线反映的是机组在实际运行条件下的真实特性,并以厂内负荷分配方案为例,验证了针对性经济运行措施的有效性。