Concept of turbines for ultrasupercritical,supercritical, and subcritical steam conditions

The article describes the design features of condensing turbines for ultrasupercritical initial steam conditions (USSC) and large-capacity cogeneration turbines for super- and subcritical steam conditions having increased steam extractions for district heating purposes. For improving the efficiency and reliability indicators of USSC turbines, it is proposed to use forced cooling of the head high-temperature thermally stressed parts of the high- and intermediate-pressure rotors, reaction-type blades of the high-pressure cylinder (HPC) and at least the first stages of the intermediate-pressure cylinder (IPC), the double-wall HPC casing with narrow flanges of its horizontal joints, a rigid HPC rotor, an extended system of regenerative steam extractions without using extractions from the HPC flow path, and the low-pressure cylinder’s inner casing moving in accordance with the IPC thermal expansions. For cogeneration turbines, it is proposed to shift the upper district heating extraction (or its significant part) to the feedwater pump turbine, which will make it possible to improve the turbine plant efficiency and arrange both district heating extractions in the IPC. In addition, in the case of using a disengaging coupling or precision conical bolts in the coupling, this solution will make it possible to disconnect the LPC in shifting the turbine to operate in the cogeneration mode. The article points out the need to intensify turbine development efforts with the use of modern methods for improving their efficiency and reliability involving, in particular, the use of relatively short 3D blades, last stages fitted with longer rotor blades, evaporation techniques for removing moisture in the last-stage diaphragm, and LPC rotor blades with radial grooves on their leading edges.     

Improvement in the corrosive fatigue damage to the low-pressure steam turbine blades due to unbalanced currents

This paper presents two improved methods for the corrosive fatigue damage to the blades of low-pressure steam turbines due to corrosive operating environments and power system unbalance. Two blade materials as AISI-403 and 17-4PH are chosen into the investigation, which provides an enhanced understanding on the effect of materials to reduce the corrosion fatigue damage of blades. To verify the validity of the proposed methods, simulated results of a 951 MW operating turbine generator for the corrosive fatigue damage are presented in this paper. From the simulated results, it can be found that the corrosive fatigue damage to the low-pressure steam turbine blades is significantly reduced. In addition, the effects of unbalanced currents (I₂) on the corrosive fatigue damage to the steam turbine blades are estimated when turbine generators operate in various stress concentration factors and corrosive conditions. The estimations may provide with the safe operating standard on the new or designed generator sets under corrosive environments.     

Prospects of using two-tier low-pressure cylinders in steam-turbine power units

Possible ways for increasing the throughput capacity of the low-pressure cylinders of the condensing steam turbines are discussed. It is shown that the use of two-tier low-pressure cylinders allows the flowrate of steam through them to be increased by 65–70% without the need of increasing the length of last-stage blades.     

Problems relating to operation of geothermal power stations stemming from the presence of admixtures in the geothermal heat carrier

The effects the specific features of chemical composition and the thermophysical properties of geothermal heat carrier have on the metal erosion-corrosion processes and on the formation of deposits during operation of a geothermal power station are analyzed. Methods for preventing the formation of deposits and making the geothermal power station equipment more resistant to erosion and corrosion are considered. Results from calculation and experimental investigations aimed at studying how the concentration of silicic acid and other admixtures vary in the working loop and turbine flow path at the Verkhne-Mutnovsk geothermal power station are presented. The possibility of using surface-active inhibitors to prevent the formation of deposits and erosion-corrosion processes in the geothermal power station equipment is demonstrated.     

Modern geothermal power: GeoPP with geothermal steam turbines

The first part of the review presents information on the scale and specific features of geothermal energy development in various countries. The classification of geothermal power plant (GeoPP) process flow diagrams by a phase state of the primary heat source (a geothermal fluid), thermodynamic cycle, and applicable turbines is proposed. Features of geothermal plants using methods of flashing and steam separation in the process loop and a flowsheet and thermodynamic process of a geothermal fluid heat-to-power conversion in a GeoPP of the most widespread type using a double-flash separation are considered. It is shown that, for combined cycle power units, the specific power-to-consumption geothermal fluid ratio is 20–25% higher than that for traditional single-loop GeoPP. Information about basic chemical components and their concentration range for geothermal fluids of various formations around the world is presented. Three historic stages of improving geothermal energy technologies are determined, such as development of high-temperature geothermal resources (dry, superheated steam) and application of a two-phase wet-steam geothermal fluid in GeoPP power units with one or two expansion pressures and development of binary cycle GeoPPs. A current trend of more active use of binary power plants in GeoPP technological processes is noted. Design features of GeoPP’s steam turbines and steam separating devices, determined by the use of low-potential geothermal saturated steam as a working medium, which is characterized by corrosion aggressiveness and a tendency to form deposits, are considered. Most promising Russian geothermal energy projects are determined. A list of today’s most advanced geothermal turbine performance technologies is presented. By an example of a 25 MW steam turbine design, made by JSC Kaluga Turbine Works, advantages of the internal moisture separation with a special turbine-separator stage are shown.     

Start-up circuit upgrading to reduce the erosion of the rotor blades of the last stages of steam turbines and prevent the mass strips of stellite plates

At turbine starts with low steam flow rates in idle mode, the low-pressure rotor blades consume energy, causing the ventilation heating of the stages and creating higher depression in them than in the condenser. This leads to the return steam flows in the exhaust of the low-pressure cylinder (LPC), reducing the heat due to the moisture of starting steam damps and cooling injections. It is shown that, as a result of upgrading with the transition to fully milled shroud platforms of rotor blades, the depression in the stages decreases and their cooling efficiency is reduced due to the removal of an elastic turn of the rotor blades under the action of centrifugal forces and seal of them by periphery. Heating the rotor blades of the last stages exceeds the temperature threshold of soldering resistance of stellite plates (150°C), and their mass strips begin. The start-up circuit providing both the temperature retention of the last stages lower the soldering resistance threshold due to overwetting the steam damps up to saturation condition and the high degree of removal from the dump steam of excessive erosive-dangerous condensed moisture was proposed, applied, and tested at the operating power unit. The investment in the development and application of the new start-up circuit are compensated in the course of a year owing to guaranteed prevention of the strips of stellite plates that lengthens the service life of the rotor blades of the last stages as well as increase of the rotor blade efficiency due to the sharp decrease of erosive wear of the profiles and reduction of their surface roughness. This reduces the annual consumption of equivalent fuel by approximately 1000 t for every 100 MW of installed capacity.     

大功率汽轮机末级长叶片超声检验方法及应用

介绍了大功率汽轮机叉型叶根叶片、枞树型叶根叶片、叶身和叶根过渡区、拉筋、围带的检测方法。提出应进一步完善和开发短前沿、小晶片、低噪声的微型探头,以提高检验结果的可靠性和准确性,为末级长叶片安全运行和监督提供有效的手段。     

大功率汽轮机末级长叶片起声检验方法及应用

介绍了大功率汽轮机叉型叶根叶片、枞树型叶根叶片、叶身和叶根过渡区、拉筋、围带的检测方法.提出应进一步完善和开发短前沿、小晶片、低噪声的微型探头,以提高检验结果的可靠性和准确性,为末级长叶片安全运行和监督提供有效的手段.     

Development, pilot commercial operation, and introduction of automated monitoring systems for LMZ K-210-12.8 turbine units

We present automated systems for monitoring and diagnostics of turbine units at the Shatura GRES-5 district power station, specifically, systems for monitoring their vibration state and the state of the last-stage blading of the low-pressure cylinder. Results are presented from the development of a channel for monitoring the pulsation characteristics of the working medium in the flow path of the steam-admission devices of an LMZ K-210-12.8-4 turbine. The relationship between unstable operating conditions of the control valves and the vibration characteristics of high-pressure rotor bearings is investigated. Results of the operation of the systems and the monitoring channels under the operational conditions of the turbine unit are presented.     

倒置微带贴片谐振器测量汽轮机湿度的研究

汽轮机蒸汽湿度的在线测量,对汽轮机的安全、经济运行具有重要的理论意义和实用价值。根据微扰法的基本理论,提出一种结构简单、灵敏度高的倒置微带贴片谐振器,实现汽轮机湿度的准确在线测量。湿蒸汽的湿度变化反应为谐振器介质层介电常数的变化,根据微带贴片谐振器的基本原理,仿真计算不同介电常数下的谐振频率,得到其变化关系曲线;讨论样本厚度、基质厚度和基质介电常数对频率偏移量的影响;设计微带贴片谐振器模型,并分别在HFSS和CST软件下进行仿真。研究及仿真结果表明,微带贴片谐振器模型适用于汽轮机蒸汽湿度的在线测量,蒸汽湿度每变化1%,谐振器频偏约为18 k Hz,约为微带缝隙谐振器频偏的3.6倍,有利于蒸汽湿度的准确测量。     

超临界压力汽轮机固体颗粒侵蚀的表面硬化处理技术

简要介绍汽轮机的固体颗粒侵蚀及其对机组安全性和经济性的危害，介绍国外为预防汽轮机通流部分的某些喷嘴和动叶固体颗粒侵蚀所采用的各种表面硬化处理技术，包括等离子喷涂和扩散渗层的现场运行经验，供我国发展高性能大容量超临界压力汽轮机及亚临界压力机组受到固体颗粒侵蚀损伤恢复其性能时参考。     

超临界直流炉首次检修化学检查共性问题及对策

总结了河南省8 台采用给水还原性全挥发处理方式的600 MW超临界直流炉机组首次检修化学检查中发现的共性问题：水冷壁、省煤器的结垢速率较高;汽轮机叶片积盐速率较高,沉积物成分复杂;机组停运揭缸后低压缸叶片有锈蚀。针对以上问题,分析了其原因,并提出了解决问题的建议。     

600MW超临界机组汽轮机低压转子末级叶片损坏原因分析

介绍某发电厂发生的一起超临界机组低压转子末级叶片损坏事故,宏观检查发现是因为反向第6级蜂窝汽封跌落引起的。进一步开展材质分析、力学性能试验、金相试验,并对蜂窝汽封的加工工艺综合分析,得出如下结论:钎焊工艺影响了汽封体的原始热处理状态,使汽封体的综合机械性能下降,而且汽封体结构不合理,加上运行蒸汽的冲击,导致汽封体跌落断裂,造成末级叶片损坏。分析结论对汽轮机的检修、改造具有指导意义。     

汽轮机热力设计平台

介绍一套集汽轮机热力设计计算、产品数据库管理、热力性能图表生成于一体的设计平台。使用该平台能够直观、快速、高效地进行汽轮机通流部分及热力方案设计。文章阐述了汽轮机通流部分及热力方案设计和数据库系统的运行环境、总体结构、各子系统结构与功能以及开发中的技术要点。     

大同二电厂600MW直接空冷汽轮机设计特点

针对国电电力大同第二发电厂二期扩建工程的600MW直接空冷汽轮机组,结合空冷机组的特点和国产600MW空冷汽轮机的主要设计原则,介绍了哈尔滨汽轮机厂有限责任公司为大同二期工程设计制造的国产首台600MW直接空冷汽轮机的低压缸、背压、低压缸末级叶片、低压缸落地轴承等技术和结构设计特点,从设计角度介绍了空冷汽轮机的主要技术规范及投运以后的机组性能状况。     

Development of High-Powered Steam Turbines by OAO NPO Central Research and Design Institute for Boilers and Turbines

The article provides an overview of the developments by OAO NPO TsKTI aimed at improvement of components and assemblies of new-generation turbine plants for ultra-supercritical steam parameters to be installed at the power-generating facilities in service. The list of the assemblies under development includes cylinder shells, the cylinder’s flow paths and rotors, seals, bearings, and rotor cooling systems. The authors consider variants of the shafting–cylinder configurations for which advanced high-pressure and intermediate-pressure cylinders with reactive blading and low-pressure cylinders of conventional design and with counter-current steam flows are proposed and high-pressure rotors, which can increase the economic efficiency and reduce the overall turbine plant dimensions. Materials intended for the equipment components that operate at high temperatures and a steam cooling technique that allows the use of cheaper steel grades owing to the reduction in the metal’s working temperature are proposed. A new promising material for the bearing surfaces is described that enables the operation at higher unit pressures. The material was tested on a full-scale test bench at OAO NPO TsKTI and a turbine in operation. Ways of controlling the erosion of the blades in the moisture–steam turbine compartments by the steam heating of the hollow guide blades are considered. To ensure the dynamic stability of the shafting, shroud and diaphragm seals that prevent the development of the destabilizing circulatory forces of the steam flow were devised and trialed. Advanced instrumentation and software are proposed to monitor the condition of the blading and thermal stresses under transient conditions, to diagnose the vibration processes, and to archive the obtained data. Attention is paid to the normalization of the electromagnetic state of the plant in order to prevent the electrolytic erosion of the plant components. The instrumentation intended for monitoring the relevant electric parameters is described.     

双区加热型汽轮机排汽湿度探针测量方法探讨

介绍了双区加热法测量蒸汽湿度的热力学基本原理,并对探针汽液两相区流动压降进行了计算,得出了判定探针蒸发段管长大于水滴汽化长度的热力学检测标准,为保证探针在测量汽轮机排汽湿度时的准确性提供了理论依据。     

A numerical analysis of the serial design of the T-250/300-23.5 cogeneration turbine low-pressure cylinder’s exhaust hood

A mathematical model of the low-pressure cylinder’s exhaust compartment used in the serial design version of the T-250/300-23.5 turbine is constructed. The exhaust compartment consists of the turbine flow path last stage, a moisture removal chamber, and an exhaust hood (the EH stage). The effect of individual elements of the low-pressure cylinder exhaust compartment’s flow path on its gas dynamic characteristics in condensing modes of operation is numerically modeled for a wide range of steam flow rates. For the compartment with the exhaust hood completely filled with its inner elements, the flow patterns are calculated in partial modes of operation with presenting data on losses and flow-averaged integral characteristics at the diffuser inlet. The calculation results have been verified against the data of full-scale and model tests.     

汽轮机排汽湿度的在线监测方法及工业试验研究

蒸汽湿度对汽轮机的安全性和经济性有重要的影响.该文提出了可以在线监测汽轮机排汽湿度的双区加热方法,将加热段分为蒸发段和过热段,各段独立加热,通过过热段测量蒸汽流量,简化了测量装置,提高了探针的可靠性.湿度测量探针设计中仔细考虑了散热损失、汽化长度、热阻力的影响,提高了测量精度,实现了对汽轮机排汽湿度的长期在线监测.对采用双区加热法研制的湿度测量探针进行了工业试验,试验结果表明测量结果是可信的.     

Investigation of Technical and Economic Viability of the 450-MW CCGT Unit’s Operation in the GTU Based CHP Mode

Technical viability and economic feasibility of improving the technology of a 450-MW CCGT unit’s participation in power load leveling of the power system operating in a GTU based CHP mode by transferring a 450-MW CCGT T-125/150 steam turbine to the driving mode instead of its shutdown are considered. It is shown that the shutdown of the steam turbine is associated with increased fuel consumption under start-up conditions, delayed steam turbine loading and the CCGT unit as a whole, and a loss of steam turbine life characteristics. The technology of transferring the 450-MW CCGT unit to the GTU based CHP mode, possible schemes of high- and low-pressure steam distributions between line water heaters, and methods and results of calculation of power parameters of the 450-MW CCGT unit with the turbine shutdown and transferring it to the driving mode in the absence and presence of peak-load heaters in the heat balance are presented. It is shown that switching the 450-MW CCGT unit from the base 290 MW electric load and 1006 GJ/h heat production to the GTU based CHP mode leads to a decrease in electric capacity of the CCGT unit by 90 MW and an increase in heat production by 335–348 GJ/h. Comparative graphs of the steam turbine start-up and the CCGT unit rated loading in the comparable variants after its operation in the GTU based CHP mode for 8–10 h are given. Evaluation techniques and results of the economic efficiency of the generator driving mode are compared with the shutdown of the steam turbine. Based on the performed calculations, it is shown that, for various combinations of fuel equivalent and electricity costs and heating tariffs, the expedient time for switching the steam turbine to the driving mode is 10–18 h. Additional advantages of the driving mode are noted, such as improvement of the steam turbine reliability due to the elimination of cyclic temperature variations of its steam-inlet elements and vibrational oscillations in the final stages of the low-pressure cylinder and the possibility of the steam turbine generator to operate as a synchronous condenser.