火电厂闭式循环水系统变工况运行优化

以某600 MW机组闭式循环水系统为例,提出了以汽轮机负荷、环境温度和环境相对湿度为条件的优化运行方式,将冷却塔、凝汽器和汽轮机变工况进行耦合,得到了闭式循环水系统冷却塔的进塔水温和出塔水温(即凝汽器循环水的出口温度和入口温度)随机组负荷、环境温度和环境相对湿度的变化规律.结果表明:在一定的环境条件和负荷下,进塔水温随循环水体积流量的增大而降低,而出塔水温随循环水体积流量的增大而升高;进塔水温和出塔水温均随着环境温度、环境相对湿度和机组负荷的升高而升高.     

锅炉变工况运行优化监控系统的实现

目前国内大量电站锅炉实行变工况运行，同时又缺乏针对不同工况运行优化的方法用以指导生产操作，致使多数系统长期运行在不良状态，由此导致的能源浪费和环境污染问题日趋严重。针对上述问题，提出了一种基于模式识别和RBF神经网络技术，在线提供不同运行工况燃烧优化的方法，并在所承担的电站锅炉自控系统改造工程实践中应用。结果表明，该方法对于变工况运行的锅炉系统具有很好的状态监测和操作指导作用，应用前景良好。     

350 MW余热锅炉变工况运行特性分析

目的  整体煤气化联合循环（IGCC）发电技术是高效、低碳的发电技术,余热锅炉是IGCC的组件之一。文章旨在研究余热锅炉变工况运行特性以提高整体煤气化联合循环发电技术的效率。 方法  通过分析余热锅炉的工作原理及传热传质原理,使用MATLAB软件展开编程计算,探究给水温度、给水压力、液相换热系数以及气相换热系数与余热锅炉内吸热量的关系。 结果  结果发现,当液相换热系数在200～1 000 W/(m²·K)和气相换热系数在20～100 W/(m²·K)范围内时,如果给水温度从30 ℃增加到100 ℃或给水压力增加,余热锅炉的吸热量将不断减少。反之,假设给水温度在30～100 ℃范围内,当液相换热系数从200 W/(m²·K)增加到1 000 W/(m²·K)或气相换热系数从20 W/(m²·K)增加到100 W/(m²·K)时,余热锅炉的吸热量不断增加。 结论  在液相换热系数与气相换热系数不变的情况下,给水温度或给水压力增加,余热锅炉的吸热量会减少;在给水温度与给水压力不变时,液相换热系数或气相换热系数增加,余热锅炉的吸热量会增加。     

蒸汽喷射式热泵变工况性能分析

采用数值模拟的方法对低压蒸汽增压利用系统中的蒸汽喷射式热泵在非设计工况下的操作性能进行研究，计算并分析了工作蒸汽压力和温度、引射流体压力及混合流体压力等热力参数对热泵操作性能的影响。数值结果表明：当混合流体的压力低于一定的数值时，喷射系数维持一定值；而热泵对引射流体压力的变化极为敏感，引射压力的微小变化可能导致热泵操作性能的急剧下降；提高工作蒸汽的压力并不一定能改善喷射泵的工作性能，这是因为提高工作蒸汽压力会增加额外的蒸汽量所致；喷射系数随工作蒸汽温度的升高而略有增大，并近似呈线性率。     

燃气－蒸汽联合循环变工况计算及汽轮机的滑参数运行

本文介绍了余热锅炉型燃气－蒸汽联合循环变工况特性计算方法，论证了汽轮机运行特点，并以实例计算结果对汽轮机的定压与滑参数运行进行了对比，证明了汽轮机滑参数运行的合理性．     

抽凝机组调节系统变工况运行

叙述了抽凝机组调节系统的实际运行情况,对其变工况运行前后状况进行了比较与分析,并就文中所述的改造提出了建议。     

电站锅炉蒸汽吹灰系统运行优化

目前,大型锅炉吹灰大多采用蒸汽吹灰方式,吹灰汽源大部分采用高品质蒸汽,蒸汽压力较高,运行中出现了一些影响机组运行安全性和经济性的问题,并且降低了机组的效率,因此,应寻求一些改进措施以减少高品质蒸汽的损耗,提高机组蒸汽利用率。针对目前某发电厂蒸汽吹灰系统存在的高品质蒸汽浪费的问题,提出以再热蒸汽汽源作为蒸汽吹灰汽源的方法,并进行分析,结果表明:采用再热蒸汽吹灰汽源的经济性非常明显。     

宣钢锅炉蒸汽系统运行模式的优化调整

通过分析宣化钢铁集团有限责任公司各台锅炉运行经济性,在满足蒸汽用量的条件下,确定锅炉启动顺序、组合运行状态和负荷分配,从而达到优化锅炉系统运行的目的,进而有效降低锅炉蒸汽电耗、节约电能.     

N135MW机组通流部分改造特点及运行状况

介绍了台州发电厂6台N125MW机组的改造情况,比较分析了三维、四维技术与东芝技术的特点及其效率试验情况,提出了设计优化措施,对其他电厂的机组改造具有借鉴意义.     

SOFC cogeneration system for building applications, part 2: System configuration and operating condition design

An SOFC (Solid Oxide Fuel Cell) cogeneration optimization study was carried out for one small-scale and one large-scale building under both hot and cold weather conditions. Several different configurations of the SOFC system are operated using a defined set of input parameters to meet the actual heating, cooling and electrical demands on those two buildings The results are discussed and compared from four different perspectives: electric-only vs. cogeneration, energetic vs. economic, large-scale vs. small-scale buildings and hot vs. cold weather conditions. The main conclusion of this study is that optimization results vary widely depending on different system configurations and loading conditions and thus SOFC systems should be optimized based on the specific conditions to which they are exposed and not simply on a single operating condition.     

Use of the task configuration system (TCS) for the design and on-line optimization of power plants operating with variable loads

The main purpose of this work is to show the ability of the TCS (task configuration system) to perform both the design and the operation optimization of power plants. The TCS is a module that permits to set the main task of each one of the equipments of the system and consequently setting how they respond to variable loads. In this work, the TCS was applied to a micro cogeneration plant of 60 kW in which both the electrical and the thermal loads were variable. Primarily, the design optimization of the nominal power of the equipments and of the TCS configuration was performed for the loads and electricity/fuel costs assumed in the design. After this operational optimizations in cases where the loads and electricity/fuel costs were doubled and then halved in relation to the standard case were performed. The results presented the TCS in a very robust way in most of the cases even the operational conditions being very different from the originally assumed. Based on the results, it is possible to defend the use of the TCS to decrease the risk of high initial investments made in cogeneration systems.     

太阳能吸收式制冷系统夏季运行方式分析

介绍一个典型太阳能吸收式制冷系统,讨论了其在夏季的各种运行方式及相应运行特性,提出了各运行模式的控制方案。     

浅谈联合循环机组蒸汽系统的运行方式

简要叙述了浙江余姚燃气-蒸汽联合循环发电机组蒸汽系统运行方式.分析了蒸汽系统运行方式特点,提出了蒸汽系统运行方式调整的技术措施,同时指出了蒸汽系统运行方式调整是提高效率的技术措施中最合理和最经济的.     

Exergy analysis of a PEM fuel cell at variable operating conditions

This paper presents a comprehensive exergy analysis of a 10 kW PEM fuel cell at variable operating temperatures, pressures, cell voltages and air stoichiometrics. The calculations of the physical and chemical exergies, mass flow rates and exergetic efficiency are performed at temperature ratios (T/T₀) and pressure ratios (P/P₀) ranging from 1 to 1.25 and 1 to 3, respectively. In addition, the analysis is conducted on fuel cell operating voltages of 0.5 and 0.6 V and at air stoichiometrics of 2, 3 and 4 in order to determine their effects on the efficiency of the fuel cell. The calculated results illustrate the significance of the operating temperature, pressure, cell voltage and air stoichiometry on the exergetic efficiency of the fuel cell. However, it is recommended that the fuel cell should operate at stoichiometric ratios less than 4 in order to maintain the relative humidity level in the product air and to avoid the membrane drying out at high operating temperatures.     

运行状态下太阳热水系统热性能测试方案

按照热力学原理、根据国家标准对已竣工的江苏五台山体育中心游泳馆太阳热水系统工程,提出了运行状态下的系统热性能验收测试方案,进行了测试工作,并取得测试结果.所提出的运行状态下的系统热性能验收测试方案,解决了工程热性能验收问题,具有实用价值.     

Experience with digital power system stabilizers at steam and hydrogenerating stations

Test results from installations of digital power system stabilizers (DPSSs) at steam and hydro generating stations by two electric utilities in Western Canada are described. Reasons for selecting digital versus analog PSSs are outlined, stabilizer design objectives are listed, and commissioning and test results are included. It is concluded that DPSS has decided advantages over analog types and should be seriously considered as a replacement for existing analog PSSs or for new installations     

On the operation strategy of steam power plants working at variable load: Technical and economic issues

The context of the deregulated energy market leads to high competitiveness among producers and requires suitable strategies in plants and systems management: strongly irregular and discontinuous operation is required in order to meet the user demand and produce energy mainly during peak hours, when the electricity price is higher. This operation strategy is generally asked of all power plants, not only those traditionally devoted to load regulation and peak request, but also those originally designed to cover the base load (steam power plants, for example). As a consequence, greater income is ensured in the short term, but a reduction in the lifetime of the most critical components is likely to occur, due to creep and thermo-mechanical fatigue loadings. This will cause additional costs associated with unplanned maintenance and unavailability of the plant if a failure occurs.This paper presents a procedure aimed at evaluating this extra cost related to flexible operation, and at assisting the management decision about power plants’ operation and maintenance scheduling. The procedure, on the basis of the historical data, predicts the residual life of the most critical components, considering the effects of creep, thermo-mechanical fatigue, welding, corrosion and oxidation. It also permits one to choose different future strategies for plant management and evaluate the residual life and the economic effects for each of them. An example of application to a real steam power plant will also be presented.     

Numerical investigation of a multichannel reactor for syngas production by methanol steam reforming at various operating conditions

A novel multichannel reactor with a bifurcation inlet manifold, a rectangular outlet manifold, and sixteen parallel minichannels with commercial CuO/ZnO/Al₂O₃ catalyst for methanol steam reforming was numerically investigated in this paper. A three-dimensional numerical model was established to study the heat and mass transfer characteristics as well as the chemical reaction rates. The numerical model adopted the triple rate kinetic model of methanol steam reforming which can accurately calculate the consumption and generation of each species in the reactor. The effects of steam to carbon molar ratio, weight hourly space velocity, operating temperature and catalyst layer thickness on the methanol steam reforming performance were evaluated and discussed. The distributions of temperature, velocity, species concentration, and reaction rates in the reactor were obtained and analyzed to explain the mechanisms of different effects. It is suggested that the operating temperature of 548 K, steam to carbon ratio of 1.3, and weight hourly space velocity of 0.67 h⁻¹ are recommended operating conditions for methanol steam reforming by the novel multichannel reactor with catalyst fully packed in the parallel minichannels.