Use of a turboexpander in steam power units for heat energy recovery in heat supply systems

A method for raising the efficiency of a boiler plant by installing a unit operating by the organic Rankine cycle is presented. Such units allow one to generate electricity to cover the auxiliaries of a heat source at a heat-transfer fluid temperature of no more than 130°С. The results of commissioning tests of boilers revealed that their efficiency is maximized under a load that is close or corresponds to the nominal one. If this load is maintained constantly, excess heat energy is produced. This excess may be used to generate electric energy in a steam power unit with a turboexpander. A way to insert this unit into the flow diagram of a boiler plant is proposed. The results of analysis of turbine types (turboexpanders included) with various capacities are presented, and the optimum type for the proposed flow diagram is chosen. The methodology for the design of turboexpanders and compressors used in the oil and gas industry and their operational data were applied in the analysis of a turboexpander. The results of the thermogasdynamic analysis of a turboexpander and the engineered shape of an axial-radial impeller are presented. Halocarbon R245fa is chosen as the working medium based on its calorimetric properties.     

Reliability and availability modelling of combined heat and power (CHP) systems

Many subsystems are involved in the reliability modeling of combined heat and power (CHP) systems, but in most studies these subsystems have not been classified and in many cases have been considered separately. Furthermore, calculating the reliability from the generation point to the consumer has not yet been studied. Herein, we classify combined heat and power subsystems and model their reliability, availability and mean-time-to-failure indices based on interactions between subsystems from the generation site to consumer delivery. The proposed CHP reliability and availability model is based on the state space and the continuous Markov method with electricity-generation, fuel-distribution and heat-generation subsystems. The effects of fuel- and water-distribution networks at the CHP site and the hot-water-distribution network on the consumer-utility reliability of CHP systems were fully assessed in an applicable case study. Additionally, we present a sensitivity analysis for island, standby and parallel operational modes of CHP systems. The results from the case study prove that improving the gas-distribution network, the network delivering hot water to the consumers and the water-delivery network to the CHP, in addition to optimizing the failure and repair rates of CHP systems, have considerable effects on the reliability improvement of the complete integrated system and have major roles in technical and economic feasibility studies of CHP systems.     

Computer models of heat supply networks and circulating systems

We consider the construction of computer models of heat supply networks and circulating systems with which the flowrates and pressure of heat carrier can be determined at any point of the network. The model is constructed on the basis of Kirchoff’s equations and graph theory. The obtained system of equations is solved using the iteration method.     

西门子V94．3A燃气轮机配套余热锅炉设计

华能上海石洞口燃机电厂燃气—蒸汽联合循环工程选用西门子V94.3A型燃气轮机,余热锅炉是国内设计生产的第一台配该型号燃机的余热锅炉。由于机组整体性能由西门子保证,故余热锅炉的系统设计必须考虑满足西门子提出的相关要求。介绍了余热锅炉主要设备的结构特点,详细介绍了配V94.3A型燃机的余热锅炉设计技术数据,可为国内大型联合循环机组余热锅炉的设计提供参考。     

New hot water boilers for heat supply systems

The design features of new hot-water water-tube boilers with capacities of 7.56, 11.63, 23.26, and 35.0 MW fitted with heating surfaces made of all-welded membrane panels and finned tubes are described together with the technical principles used for developing them.     

联合循环机组余热锅炉主要调节系统设计实践

介绍了GE109FA型390MW单轴燃气—蒸汽联合循环机组余热锅炉主要控制系统的设计思想,着重叙述了负荷、汽包水位、主蒸汽温度、旁路压力和温度控制系统、高压汽包和中压汽包抽汽控制以及燃机排汽匹配温度与匹配速率计算。     

A study of natural circulation in the evaporator of a horizontal-tube heat recovery steam generator

Results obtained from investigations of stable natural circulation in an intricate circulation circuit with a horizontal layout of the tubes of evaporating surface having a negative useful head are presented. The possibility of making a shift from using multiple forced circulation organized by means of a circulation pump to natural circulation in vertical heat recovery steam generator is estimated. Criteria for characterizing the performance reliability and efficiency of a horizontal evaporator with negative useful head are proposed. The influence of various design solutions on circulation robustness is considered. With due regard of the optimal parameters, the most efficient and least costly methods are proposed for achieving more stable circulation in a vertical heat recovery steam generator when a shift is made from multiple forced to natural circulation. A procedure for calculating the circulation parameters and an algorithm for checking evaporator performance reliability are developed, and recommendations for the design of heat recovery steam generator, nonheated parts of natural circulation circuit, and evaporating surface are suggested.     

浅谈大型联合循环机组的余热锅炉

分析了大型燃气-蒸汽联合循环机组余热锅炉补燃与不补燃的应用条件及各自特点,给出了几种蒸汽轮机循环系统的布置方案,并分析了蒸汽循环系统的选择方法,对余热锅炉型式进行了分析比较。     

Thermal and chemical tests of the steam generator of unit 3 at the Kalinin nuclear power station

The results obtained from combined thermal and chemical tests of the steam generator of Unit 3 at the Kalinin nuclear power station are summarized. The obtained data are compared with the results of thermal and chemical tests carried out on steam generators at other nuclear power stations equipped with VVER-1000 reactors, and recommendations on selecting the steam-generator blowdown schedule are given.     

Investigation of failures in operation of heat networks of large heat supply systems

The effect of deviations in heat network parameters on operation of heating system and hot-water supply systems in buildings is examined. The consequences of a decrease in the water temperature in a heat network under extreme weather conditions in a range below the design ambient air temperature, the efficiency of disconnection of a hot water supply system (HWSS) heater in this period, and deviations in the normal heat supply in the transition period at relatively high outdoor temperatures are considered. The specific and scope of failures depend on the design-heating load to design hot water supply load ratio for the heat network. A mathematical model was developed, and numerical investigation was performed of modern schemes of heat points which are designed primarily for covering the hot water supply load and recovering the heating system heat output in case of low or no hot water consumption in HWSS. The performed calculations demonstrate that the heating system has no time to restore its heat output, thereby considerably reducing air temperature in the heated premises. The lower the ambient air temperature and the lower the ratio of the design loads for hot water supply and heating, the greater is this decrease. At the same time, in case of a sudden decrease in the outdoor temperature and an accident in the heat supply system, the heating system must be the priority consumer, since a heating failure not only decreases the thermal comfort of consumers but can cause emergency situations in local utility systems, such as a cold water supply system. Correction of failures in a heat supply system requires calculation of operating conditions of heat networks.     

An increase in the efficiency of heat supply systems on reconstruction of energy sources and modernization of gas supply systems

The present paper deals with technical and economic problems related to an increase in the efficiency of the use of natural gas on reconstruction of the hest supply systems in the urban-type settlement of Nogliki, with the use of combined heat and power production at the local gas-turbine-based power plant.     

大型天然气联合循环电厂对余热锅炉蒸汽系统的选择

为迎接西气东输和液化天然气的输人，我国东部地区正准备建设一批大型联合循环电厂。为使建成后的电厂单位投资少、热效率高、投产后具有较好的效益，选择合适的余热锅炉蒸汽系统至关重要。对我国急需建设的大型天然气联合循环电厂的余热锅炉蒸汽系统中有关余热锅炉节点温差和接近点温差的选取、蒸汽压力级数的选择、排烟温度的高低、烟气阻力的大小、蒸汽参数和再热的确定、给水的加热和除氧方式及炉型的选择进行分析和研究，得出明确的优化结论。     

Expedient arrangement of newly constructed systems for centralized heat supply

It is shown that for newly constructed combined-cycle cogeneration plants and nuclear cogeneration plants, the optimum arrangement of the centralized heat supply system is the combination of a cogeneration plant and a district heat-supply station (a boiler house).     

Methods for analyzing thermal-hydraulic operating conditions of large heat supply systems

Mathematical models of large heat supply systems with arbitrary configuration (highly branched and multiloop) and structure are presented, and methods for calculating their steady and dynamic thermal-hydraulic operating conditions are considered.     

家用燃料电池热电联供系统的建模与仿真

家用燃料电池热电联供系统是一种清洁高效的分布式发电方式,近年来发展迅猛。开展家用热电联供系统建模与仿真,对于构建热电联供实际系统具有一定指导意义。在Matlab/Simulink平台上搭建了千瓦级燃料电池热电联供系统(包括电模型和热模型),电模型包含氢氧供应子系统、质子交换膜燃料电池模型以及功率控制模型;热模型包括热管理子系统和辅助热水器等模型。基于此热电联供模型,进行了燃料电池发电系统动态特性分析,然后采用电跟随策略,通过参考模拟工况下的电负荷与热负荷曲线研究了可变负载下系统的动态行为。仿真结果表明,该系统在热负荷与电负荷上都有较短的响应时间和较高的控制精度。     

Comparative analysis of cooling systems for energy equipment of combined heat and power plants and nuclear power plants

In the 20th century, the thermal power engineering in this country was oriented toward oncethrough cooling systems. More than 50% of the CHPP and NPP capacities with once-through cooling systems put into operation before the 1990s were large-scale water consumers but with minimum irretrievable water consumption. In 1995, the Water Code of the Russian Federation was adopted in which restrictions on application of once-through cooling systems for newly designed combined heat and power plants (CHPPs) were introduced for the first time. A ban on application of once-through systems was imposed by the current Water Code of the Russian Federation (Federal law no. 74-FZ, Art. 60 Cl. 4) not only for new CHPPs but also for those to be modified. Clause 4 of Article 60 of the Water Code of the Russian Federation contravenes law no. 7-FZ “On Protection of the Environment” that has priority significance, since the water environment is only part of the natural environment and those articles of the Water Code of the Russian Federation that are related directly to electric power engineering, viz., Articles 46 and 62. In recent decades, the search for means to increase revenue charges and the economic pressure on the thermal power industry caused introduction by law of charges for use of water by cooling systems irrespective of the latter’s impact on the water quality of the source, the environment, the economic efficiency of the power production, and the living conditions of the people. The long-range annual increase in the water use charges forces the power generating companies to switch transfer once-through service water supply installations to recirculating water supply systems and once-through–recirculating systems with multiple reuse of warm water, which drastically reduces the technical, economic, and ecological characteristic of the power plant operation and also results in increasing power rates for the population. This work comprehensively substantiates the demands of power engineering specialists that the ban on development and construction of once-through service water supply systems should be lifted and the proposals for new parameters, e.g., temperature and back pressure, for designing low-potential equipment of steam-gas and steam-power plants.     

Use of multilevel modeling for determining optimal parameters of heat supply systems

The problem of finding optimal parameters of a heat-supply system (HSS) is in ensuring the required throughput capacity of a heat network by determining pipeline diameters and characteristics and location of pumping stations. Effective methods for solving this problem, i.e., the method of stepwise optimization based on the concept of dynamic programming and the method of multicircuit optimization, were proposed in the context of the hydraulic circuit theory developed at Melentiev Energy Systems Institute (Siberian Branch, Russian Academy of Sciences). These methods enable us to determine optimal parameters of various types of piping systems due to flexible adaptability of the calculation procedure to intricate nonlinear mathematical models describing features of used equipment items and methods of their construction and operation. The new and most significant results achieved in developing methodological support and software for finding optimal parameters of complex heat supply systems are presented: a new procedure for solving the problem based on multilevel decomposition of a heat network model that makes it possible to proceed from the initial problem to a set of interrelated, less cumbersome subproblems with reduced dimensionality; a new algorithm implementing the method of multicircuit optimization and focused on the calculation of a hierarchical model of a heat supply system; the SOSNA software system for determining optimum parameters of intricate heat-supply systems and implementing the developed methodological foundation. The proposed procedure and algorithm enable us to solve engineering problems of finding the optimal parameters of multicircuit heat supply systems having large (real) dimensionality, and are applied in solving urgent problems related to the optimal development and reconstruction of these systems. The developed methodological foundation and software can be used for designing heat supply systems in the Central and the Admiralty regions in St. Petersburg, the city of Bratsk, and the Magistral’nyi settlement.     

300 MW汽轮发电机故障修复

简述益阳电厂1号发电机故障现象及原因,介绍在进行定子铁芯修复、线棒绝缘损坏后更换、转子绕组绝缘隔板处理过程中的修复方案、修复工艺及检修经验,并提出了避免同类型机组定子铁芯、线棒绝缘损坏的建议。     

An integrated approach for optimizing the operation of modern heat supply systems

We discuss matters concerned with applying an integrated approach for optimizing the operation of modern heat supply systems on the basis of constructing interconnected models of heat consumers, heat networks, and heat supply sources together with carrying out experimental field studies of the real state of a system, and with correcting the distribution of flows and the set of equipment used at stations distributing heat to consumers. Two examples of using the method for closed- and open-circuit systems are given.