Selecting the initial steam temperatures in starting combined-cycle plants in compliance with the conditions of heating the high-pressure steam superheater outlet headers

Results from an analysis of permissible initial steam temperatures and heating rates of the outlet headers of high-pressure steam superheaters and the steam lines of combined-cycle plants at which their cyclic strength is ensured are presented. A procedure is proposed using which startup assignment schedules for different thermal states can be constructed proceeding from the heating rates and initial steam temperatures selected depending on the initial temperature state of the high-pressure steam superheaters’ outlet headers.     

International water and steam quality standards on thermal power plants at all-volatile treatment

One of the methods for the improvement of reliability and efficiency of the equipment at heat power plants is the decrease in the rate of corrosion of structural materials and sedimentation in water/steam circuit. These processes can be reduced to minimum by using the water with low impurity content and coolant treatment. For many years, water and steam quality standards were developed in various countries (United States, Germany, Japan, etc.) for specific types of equipment. The International Association for the Properties of Water and Steam (IAPWS), which brings together specialists from 21 countries, developed the water and steam quality standards for various types of power equipment based on theoretical studies and long-term operating experience of power equipment. Recently, various water-chemistry conditions are applied on heatpower equipment including conventional boilers and HRSGs with combined cycle power plants (Combined Cycle Power Plants (CCPP)). In paper, the maintenance conditions of water chemistry with ammonia or volatile amine dosing are described: reducing AVT(R), oxidizing AVT(O), and oxygen OT. Each of them is provided by the water and steam quality standards and recommendations are given on their maintenance under various operation conditions. It is noted that the quality control of heat carrier must be carried out with a particular care on the HPPs with combined cycle gas turbine units, where frequent starts and halts are performed.     

燃气蒸汽联合循环机组的技术发展概况及其主要设计原则

随着我国能源结构的调整和环保要求的日益提高,燃气－蒸汽联合循环电厂将逐渐增多,因此,文章着重对国内外燃气－蒸汽联合循环技术的发展状况,燃气－蒸汽联合循环电厂技术及设备国产化的情况和目前我国对燃气－燃气联合循环电厂的设计技术原则进行了阐述。     

燃气-蒸汽联合循环机组的实时数字仿真建模

为了弥补国内对燃气-蒸汽联合循环电厂(Combined Cycle Power Plant,CCPP)中机组动态模型研究的不足,解决常用的电力系统仿真软件不提供CCPP仿真模型的问题,针对国内9F级重型CCPP机组所具有的不补燃余热锅炉、单轴型结构、滑压运行等特点,研究并建立了CCPP机组的实时数字仿真模型。首先在Matlab/Simulink环境下建立了非实时数字仿真模型,然后将其转换为C语言代码,并利用CBuilder工具将其封装为可以实时运行的仿真模型。最后,在RTDS上对模型进行了仿真测试,并与现场实测结果进行了对比验证。仿真结果表明,所建立的CCPP机组模型在计算效率和模型精确性等方面均能满足电力系统的实时仿真要求。     

An Analysis of the Effect of Protective Films on the Inside Surface of Headers and Steam Pipelines in Combined-Cycle Power Plants on Their Thermally Stressed State

The outlet header of the high-pressure superheater is among the critical components affecting the service life of heat recovery steam generators (HRSG) of combined-cycle power plants (CCPP). Headers, heat-transfer tubes, and steam pipelines are protected against corrosion by running proper water chemistry to form thin protective films on the surfaces. These films formed on the inside surface of heat-transfer tubes protect against corrosion and also reduce thermal stresses in the tube walls during transients. They are formed on the inside of tube systems of HRSGs in CCPPs at temperatures above 230°С and with good deaeration. Results are presented of a numerical analysis of the influence of thin protective films on the state of thermal stresses in headers and steam pipelines of HRSGs used in CCPPs during various transients induced, for example, by startups from different initial thermal state or thermal shocks. Predictions were obtained for different film thicknesses assuming that the film thermal conductivity was less than thermal conductivity of the pipeline metal. The numerical results enabled the determination of the heating-up modes for headers and steam pipelines under which the effect of protective films is the greatest. It is demonstrated that the protective films have a considerable effect on stresses and damage accumulation in the pipeline wall induced basically by large temperature disturbances, such as thermal shocks. The effect of protective films on the thermally stressed state of unheated pipes was assessed by reducing the resourse consumption and accumulation of equivalent operating hours during transients. It is demonstrated that a 50 μm thick protective film alone can increase the service life of an HP steam superheater’s outlet header with a standard size of 426 × 34 mm by 6%.     

An investigation of the effects of separating pressure on the efficiency and the reliability of three-circuit combined-cycle power plants with steam reheating

The authors discuss the influence of selection of the separating pressure in designing three-circuit combined-cycle power plants (CCPP) with steam reheating on their technical and economical characteristics. The changes occurring in steam flow rates in the circuits, as well as in the efficiency of the waste heat recovery boiler (WHRB), the dryness factor, heat drops, the capacity and the efficiency of the steam turbine cylinders, the efficiency of the steam turbine and the CCPP as a whole, with the changes in the separating pressure, have been analyzed. It has been shown that the optimum separating pressure for the steam-power cycle with subcritical steam conditions ranges from 2.0 to 2.5 MPa.     

蒸汽参数对电厂热经济性影响的研究

文章介绍了蒸汽初参数和终参数对大型火力发电机组热经济性的一些影响,详细阐述了提高初温和初压对理想循环热效率和对汽轮机绝对内效率的影响,阐明了提高蒸汽初温和初压所受到的限制,叙述了降低蒸汽终参数对电厂热经济性的影响以及所受到的限制.     

超超临界锅炉新型耐热钢VM12

在超临界火电机组领域,当前实际应用的铁素体耐热钢最高运行蒸汽温度为620°C左右,德国瓦卢瑞克曼内斯曼钢厂的VM12设计工作蒸汽温度可达650°C,初期的实验室及工业化试制试验结果证明,VM12的抗蠕变及抗蒸汽氧化性能可以满足650°C下服役要求,并具有良好的可加工性。详细介绍了VM12的试验过程及结果。     

风电-碳捕集电厂联合运行的电力系统优化调度

碳捕集电厂的灵活运行方式使得其净出力的快速可调成为可能,利用碳捕集电厂灵活运行方式,将风电和碳捕集电厂联合调度,平抑风电的波动性,减小风电波动对系统造成的影响。通过引入火电机组成本、碳交易成本和风-碳捕集电厂联合出力波动最小的目标函数,兼顾系统的经济、低碳、安全效益。通过多目标粒子群算法求解模型,并用混沌搜索减小碳捕集电厂总出力对平抑风电波动的影响,通过改变权系数转换矩阵参数实现调度的灵活可调。算例分析验证所提模型的可行性和有效性。     

火电厂主汽温模糊控制优化

针对火电厂普遍存在的过热汽温调节特性差、经常出现过热器汽温超调的问题,根据先进控制理论,对主汽温控制回路进行了改进,在PID串级控制的基础上,引入模糊控制增量的修正和模糊控制切换器,并在MATLAB上进行了仿真试验.在试验验证的基础上,在DCS系统上进行了实际应用,取得了良好的效果.     

Equations for calculating the properties of dissociated steam

The equations of state for dissociated steam have been developed in the temperature and pressure ranges of 1250–2300 K and 0.01–10.00 MPa for calculating thermodynamic processes in thermal power units operating on high-temperature steam. These equations are based on the property tables for dissociated steam derived at a reference temperature of 0 K. It is assumed that the initial substance is steam, the dissociation of which—in accordance with the most likely chemical reactions—results in formation of molecules of hydrogen, oxygen, steam, hydroxyl, and atoms of oxygen and hydrogen. Differential thermodynamic correlations, considering a change in the chemical potential and the composition of the mixture, during the steam dissociation are used. A reference temperature of 0.01°С used in the calculation of parameters of nondissociated steam has been adopted to predict processes in thermal power units without matching the reference temperatures and to account for transformation of dissociated steam into its usual form for which there is the international system of equations with the water triple point of 0.01°С taken as the reference. In the investigated region, the deviation of dissociated steam properties from those of nondissociated steam, which increases with decreasing the pressure or increasing the temperature, was determined. For a pressure of 0.02 MPa and a temperature of 2200 K, these deviations are 512 kJ/kg for the enthalpy, 0.2574 kJ/(kg K) for the entropy, and 3.431 kJ/(kg K) for the heat capacity at constant pressure. The maximum deviation of the dissociated steam properties calculated by the developed equations from the handbook values that these equations are based on does not exceed 0.03–0.05%.     

National and International Guidelines for the Use of Reagents Containing Film-Forming Amines for the Organization of TPP Water Chemistry Regime

The reliability and economy of thermal power plant equipment, including combined-cycle plants, are affected by corrosion of structural materials and deposit formation in the water-steam circuit. To reduce the rate of these processes, coolant treatment is used. Ammonia, hydrazine, phosphates, etc. have been traditionally used as reagents. Recently, much attention has been paid to the use of water chemistry with the addition of complex reagents based on film-forming amines, not only for the equipment protection during the established operation mode but also for start-stops and preservation. Such water chemistry regimes are used not only in Russia but also in other countries for steam turbine and combined-cycle TPP, including biomass TPPs. The International Association for the Properties of Water and Steam, uniting specialists from all over the world, developed a guideline in 2016 for the use of such reagents based on theoretical studies and years of operational experience in power equipment in 21 countries. The review of domestic and international guidelines containing conditions for the use of film-forming amines and amine-based reagents for the organization of TPP water chemistry regimes for steam turbines and combined-cycle plants is presented.     

火力发电厂建设中如何实现降低厂用电耗的要求

针对火力发电厂如何减少厂用电耗的问题 ,提出了工程设计时应考虑主机对工艺介质的要求、合理的工艺流程及工艺控制、可靠的辅机设备、电动机及启动设备的选择等。     

满意优化在火电厂汽温控制系统中的应用

满意控制原理自诞生以来在许多领域产生了一定的影响，然而满意优化在火电厂汽温控制系统中的应用研究在国内尚未见报道。文中分析了满意优化在火电厂汽温控制系统中的研究内容，给出了相应的满意算法，并成功地把基于满意优化的主蒸汽、再热蒸汽控制策略应用到工程实践中，取得了满意的效果。     

The choice of the design features of maneuverable combined-cycle units for new Russian power plants

The design features are treated of combined-cycle units (CCUs) utilizing V94.3A Siemens, GTE-110 Saturn, and GTE-160 LMZ gas turbines for the purpose of constructing new power plants in Russia designed to meet the requirement of high maneuverability. The problem is discussed of employing bypass smoke stacks for different CCU options with a view to improving their maneuverability and advance commissioning of a new power.     

Prospects for the development of coal-steam plants in Russia

Evaluation of the technical state of the modern coal-fired power plants and quality of coal consumed by Russian thermal power plants (TPP) is provided. Measures aimed at improving the economic and environmental performance of operating 150–800 MW coal power units are considered. Ways of efficient use of technical methods of NO _x control and electrostatic precipitators’ upgrade for improving the efficiency of ash trapping are summarized. Examples of turbine and boiler equipment efficiency upgrading through its deep modernization are presented. The necessity of the development and introduction of new technologies in the coal-fired power industry is shown. Basic technical requirements for a 660–800 MW power unit with the steam conditions of 28 MPa, 600/600°C are listed. Design solutions taking into account features of Russian coal combustion are considered. A field of application of circulating fluidized bed (CFB) boilers and their effectiveness are indicated. The results of development of a new generation coal-fired TPP, including a steam turbine with an increased efficiency of the compartments and disengaging clutch, an elevated steam conditions boiler, and a highly efficient NO _x /SO₂ and ash particles emission control system are provided. In this case, the resulting ash and slag are not to be sent to the ash dumps and are to be used to a maximum advantage. Technical solutions to improve the efficiency of coal gasification combined cycle plants (CCP) are considered. A trial plant based on a 16 MW gas turbine plant (GTP) and an air-blown gasifier is designed as a prototype of a high-power CCP. The necessity of a state-supported technical reequipment and development program of operating coal-fired power units, as well as putting into production of new generation coal-fired power plants, is noted.     

煤耗高的原因分析和降低煤耗的建议

节能降耗是国家提出可持续发展战略的一项重要举措，对于火力发电厂来说，降低供电煤耗是节约成本、提高市场竞争力的一项非常重要的工作。针对国华盘电公司发电煤耗高的情况从汽轮机角度进行了分析，同时根据设备状况提出了一些可行的降低煤耗的建议。     

火电厂热工控制系统的故障诊断研究

结合火电厂的实际情况，确定了热工控制系统中的故障诊断对象、常见故障类型和故障诊断方法；对系统中重要传感器、执行器的常见故障提出了基于信号分析和数据统计的诊断方法。以某300MW机组过热汽温控制系统为例，对传感器的断线、增益、偏差和超速等故障以及执行器的卡死、滞环、粘滞一滑动等故障的诊断进行研究，最后给出两个诊断实例。     

Methodical principles of multicriterial optimization of daily operating conditions of power equipment at thermal power stations

We describe a procedure for optimizing the long-and short-term operating conditions of the equipment at thermal power stations that is based on a multicriterial approach and takes into account the factors of economic efficiency, reliability, and maneuverability     

汽轮机转子在线故障诊断系统

汽化机转子在线故障诊断是关系到发电厂安全运行的重要课题之一。为此,开发了基于Windows,采用DELPHI语言编程的汽轮机在线故障诊断系统（TRFDS）。其硬件包括传感器、振动数据采集卡和计算机设备;系统软件包括数据采集、振动信号的监测及分析,模糊故障诊断、数据库管理功能模块及其它辅助软件。TRFDS具有操作简单、采集分析速度快、精度高、故障诊断和预测功能较强等特点,模拟实验表明,该系统能满足现场在线监测和故障诊断的要求。