Modern geothermal power: Binary cycle geothermal power plants

In the second part of the review of modern geothermal power plant technologies and equipment, a role, a usage scale, and features of application of binary cycle plants in the geothermal economy are considered. Data on the use of low-boiling fluids, their impact on thermal parameters and performance of geothermal binary power units are presented. A retrospective of the use of various low-boiling fluids in industrial binary power units in the world since 1965 is shown. It is noted that the current generating capacity of binary power units running on hydrocarbons is equal to approximately 82.7% of the total installed capacity of all the binary power units in the world. At the same time over the past 5 years, the total installed capacity of geothermal binary power units in 25 countries increased by more than 50%, reaching nearly 1800 MW (hereinafter electric power is indicated), by 2015. A vast majority of the existing binary power plants recovers heat of geothermal fluid in the range of 100–200°C. Binary cycle power plants have an average unit capacity of 6.3 MW, 30.4 MW at single-flash power plants, 37.4 MW at double-flash plants, and 45.4 MW at power plants working on superheated steam. The largest binary cycle geothermal power plants (GeoPP) with an installed capacity of over 60 MW are in operation in the United States and the Philippines. In most cases, binary plants are involved in the production process together with a steam cycle. Requirements to the fluid ensuring safety, reliability, and efficiency of binary power plants using heat of geothermal fluid are determined, and differences and features of their technological processes are shown. Application of binary cycle plants in the technological process of combined GeoPPs makes it possible to recover geothermal fluid more efficiently. Features and advantages of binary cycle plants using multiple fluids, including a Kalina Cycle, are analyzed. Technical characteristics of binary cycle plants produced by various manufacturers are considered, and data on the Russian pilot binary geothermal power unit in the Pauzhetskaya GeoPP is provided. Expediency of the use of binary cycle plants for autonomous power supply and energy extension of existing GeoPPs without drilling extra wells and in flowsheets of newly designed combined GeoPPs are noted.     

Evaluating the Effect from Constructing Binary Geothermal Power Units Based on Spent Petroleum and Gas Boreholes in the South Regions of Russia

The article substantiates the possibility of efficiently harnessing the geothermal resources available in the North Caucasian region through constructing binary geothermal power plants (GeoTPPs) using idle petroleum and gas wells. The power capacities of GeoTPPs are evaluated, and the basic characteristics of these power plants in case of constructing them in the promising areas are determined. The overall useful GeoTPP capacity equal to approximately 330 MW can be obtained from using the entire fleet of idle wells available in these areas. Diagrams confirming the possibility of reaching the optimal flowrate of geothermal heat carrier circulating in the geothermal circulation system loop are presented. This flowrate corresponds to a binary GeoTPP’s maximal useful power output. The article shows, taking the Ternair geothermal field as an example, that it is inefficient to use medium-enthalpy thermal waters for generating energy at a binary GeoTPP involving reinjection of a spent heat carrier. It is shown that good prospects can be expected from applying a hybrid geothermal and combined-cycle technology, by means of which it is possible to use lowenthalpy (80–100°С) thermal waters for generating electricity in a highly efficient manner. In accordance with such technology, geothermal heat is used in the binary GeoTPP cycle for heating low-boiling working fluid to its evaporation temperature. The working fluid is evaporated and superheated by using the heat of exhaust gases from a gas turbine power unit. Owing to combined use of the thermal water heat potential and the heat of exhaust gases from a gas turbine power plant in a hybrid process system, it becomes possible to obtain high power performance indicators of hybrid geothermal and combined-cycle power plants. This conclusion is confirmed by the results from numerical evaluations carried out as applied to the Ternair geothermal field. With the fully harnessed resource potential of the Ternair field, the total capacity of hybrid geothermal and combined-cycle power plants may reach 60 MW, a level that would make it possible to relieve a significant part of energy, environmental, economic, and social problems faced by the city of Makhachkala.     

大容量地热有机朗肯循环发电机组配置研究

地热发电是地热能利用的最重要方式之一,目前我国地热发电装机容量较小,技术发展缓慢,未能满足可再生能源多样化、平衡发展的要求。以某地热电站二期项目为例,通过对地热资源品质分析,建立大容量有机工质朗肯循环发电系统模型,对发电机组配置进行研究,并对系统性能进行预测分析。当室外温度为0℃时,机组可满负荷17.6 MW运行,室外温度小于0℃时,最高发电功率可达19 MW以上。     

Geothermal Power Supply Systems around the World and in Russia: State of the Art and Future Prospects

Solar and geothermal energy systems are shown to have received the widest use among all kinds of renewable sources of energy for heat supply purposes around the world. The power capacities and amounts of thermal energy generated by solar and geothermal heat supply systems around the world are presented by way of comparison. The thermal power capacity of solar heat supply systems installed around the world as of 2015 totaled 268.1 GW, and the thermal energy generated by them amounted to 225 TW h/year. The thermal power capacity of geothermal heat supply systems installed around the world totaled 70.3 GW, and the thermal energy generated by them amounted to 163 TW h/year. Information on the geothermal heat supply systems in the leading countries around the world based on the data reported at the World Geothermal Congress held in 2015 is presented. It is shown that China, with the installed thermal power capacities of its geothermal heat supply stations totaling 17.87 GW and the amount of thermal energy generated per annum equal to 48.435 TW h/year, is the world’s leader in this respect. The structures of geothermal heat supply systems by the kinds of heat consumption used around the world are presented. The systems equipped with geothermal heat pumps accounted for 70.95% in the total installed capacity and for 55.3% in the total amount of generated heat. For systems that do not use heat pumps, those serving for pools account for the largest share amounting to 44.74% in installed capacity and to 45.43% in generated heat. A total of 2218 geothermal wells with the total length equal to 9534 km (with 38.7% of them for heat supply purposes) were drilled in 42 countries in the period from 2010 to 2014. In Russia, geothermal heat supply systems are in operation mainly in Dagestan, in Krasnodar krai, and in Kamchatka. The majority of these systems have been made without breaking the stream after the well outlet. A cyclic control arrangement is also used. The combined geothermal and solar heat supply system with an installed thermal power capacity of 5 MW that is in operation in the Rozovyi settlement, Krasnodar krai, is described. In the summer time, the solar installation with a capacity of 115 kW is used for supplying hot water to residential houses and for restoring the geothermal well pore pressure. The basic process circuit and characteristics of the geothermal heat supply system with the installed thermal power capacity of 8.7 MW operating in the Khankala settlement, the city of Groznyi, are given. The specific feature of this system is that the spent geothermal heat carrier is reinjected into a specially drilled inclined well. Advanced geothermal heat supply technologies involving reinjection of the spent geothermal heat carrier, combination with binary power units, use of heat pumps for recovering the spent heat carrier, and protection of equipment from corrosion and deposits are proposed.     

Choice of optimal working fluid for binary power plants at extremely low temperature brine

The geothermal energy development problems based on using binary power plants utilizing lowpotential geothermal resources are considered. It is shown that one of the possible ways of increasing the efficiency of heat utilization of geothermal brine in a wide temperature range is the use of multistage power systems with series-connected binary power plants based on incremental primary energy conversion. Some practically significant results of design-analytical investigations of physicochemical properties of various organic substances and their influence on the main parameters of the flowsheet and the technical and operational characteristics of heat-mechanical and heat-exchange equipment for binary power plant operating on extremely-low temperature geothermal brine (70°С) are presented. The calculation results of geothermal brine specific flow rate, capacity (net), and other operation characteristics of binary power plants with the capacity of 2.5 MW at using various organic substances are a practical interest. It is shown that the working fluid selection significantly influences on the parameters of the flowsheet and the operational characteristics of the binary power plant, and the problem of selection of working fluid is in the search for compromise based on the priorities in the field of efficiency, safety, and ecology criteria of a binary power plant. It is proposed in the investigations on the working fluid selection of the binary plant to use the plotting method of multiaxis complex diagrams of relative parameters and characteristic of binary power plants. Some examples of plotting and analyzing these diagrams intended to choose the working fluid provided that the efficiency of geothermal brine is taken as main priority.     

俄罗斯穆特诺夫斯克现代地热电站的建设

俄罗斯穆特诺夫斯克地热电站总装机容量50MW，是一座在电力和热能生产上有重大突破的新型样板地热电站。为此，介绍了穆特诺夫斯克现代地热电站现状，对地热电站设备、汽轮发电机组、热力系统结构与特点作了阐述。地热发电与传统燃煤、燃油、燃气电厂相比，具有生态洁净、节约燃料运输贮存和管理费用、建设周期较短等优势。鉴于目前我国地热发电正处于起步阶段，地热发电装机容量只占世界上地热电站的装机总容量很少份额，因而可加快我国地热资源的开发应用，促进我国地热电站的发展。     

Combined cycle power unit with a binary system based on waste geothermal brine at Mutnovsk geothermal power plant

The Russian geothermal power systems developed in the last few decades outperform their counterparts around the world in many respects. However, all Russian geothermal power stations employ steam as the geothermal fluid and discard the accompanying geothermal brine. In reality, the power of the existing Russian geothermal power stations may be increased without drilling more wells, if the waste brine is employed in combined cycle systems with steam and binary turbine units. For the example of the 50 MW Mutnovsk geothermal power plant, the optimal combined cycle power unit based on the waste geothermal brine is considered. It is of great interest to determine how the thermodynamic parameters of the secondary steam in the expansion unit and the pressure in the condenser affect the performance of the equipment in the combined cycle power unit at Mutnovsk geothermal power plant. For the utilization of the waste geothermal brine at Mutnovsk geothermal power plant, the optimal air temperature in the condensers of the combined cycle power unit is +5°C. The use of secondary steam obtained by flashing of the geothermal brine at Mutnovsk geothermal power plant 1 at a pressure of 0.2 MPa permits the generation of up to 8 MW of electric power in steam turbines and additional power of 5 MW in the turbines of the binary cycle.     

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.     

热泵技术回收火电厂循环水余热的研究

热泵是利用一部分高质能从低位热源中吸取一部分热量,并把这两部分能量一起输送到需要较高温度的环境或介质的设备.火电厂循环水中存在大量余热,利用热泵技术将有效回收这部分热量用于冬季供暖或常年加热凝结水.对热泵技术回收火电厂排汽潜热及循环水余热的5种方式进行综合阐述,同时根据热泵系统的冷凝器取代低压加热器的循环方式,以3台额...     

Prospects of development of highly mineralized high-temperature resources of the Tarumovskoye geothermal field

The promising nature of integrated processing of high-temperature geothermal brines of the Tarumovskoye geothermal field is shown. Thermal energy of a geothermal brine can be converted to the electric power at a binary geothermal power plant (GPP) based on low-boiling working substance. The thermodynamic Rankine cycles are considered which are implemented in the GPP secondary loop at different evaporation temperatures of the working substance―isobutane. Among them, the most efficient cycle from the standpoint of attaining a maximum power is the supercritical one which is close to the so-called triangular cycle with an evaporation pressure of р_e = 5.0 MPa. The used low-temperature brine is supplied from the GPP to a chemical plant, where main chemical components (lithium carbonate, burnt magnesia, calcium carbonate, and sodium chloride) are extracted from it according to the developed technology of comprehensive utilization of geothermal brines of chloride-sodium type. The waste water is delivered to the geotechnological complex and other consumers. For producing valuable inorganic materials, the electric power generated at the GPP is used. Owing to this, the total self-sufficiency of production and independence from external conditions is achieved. The advantages of the proposed geotechnological complex are the full utilization of the heat potential and the extraction of main chemical components of multiparameter geothermal resources. In this case, there is no need for reverse pumping, which eliminates the significant capital costs for building injection wells and a pumping station and the operating costs for their service. A characteristic of the modern state of the field and estimated figures of the integrated processing of high-temperature brines of well no. 6 are given, from which it follows that the proposed technology has a high efficiency. The comprehensive development of the field resources will make it possible to improve the economic structure of the region and fully meet the needs of Russia in lithium carbonate and sodium chloride.     

Equipment of the binary-cycle geothermal power unit at the Pauzhet geothermal power station

The equipment of and technological processes in the pilot industrial model of the domestically produced binary-cycle geothermal power unit operating on the discharge separate at the Pauzhet geothermal power station are considered. The development principles, the design and operational features, and the data on selecting the metal in manufacturing the main equipment of the 2.5-MW binary power unit of the geothermal power station are described.     

Development of geothermal power engineering technologies in Russia

The present state of geothermal power engineering in Russia and prospects for its development are considered. An assessment is given of the projects of constructing a pilot binary geothermal power plant in Kamchatka, developing geothermal heat supply systems in the town of Vilyuchinsk and settlement of Rozovyi, and increasing the installed capacity of the Mutnovsk geothermal power station, which are the top-priority projects implemented by OAO RusGidro with scientific and technical support from ZAO GEOINKOM and ZAO Geoterm-EM.     

高背压双抽热电联产机组联合运行特性及负荷分配

大型汽轮机组采用高背压方式进行供热能够尽可能多利用排汽余热,节能效果显著,在热负荷允许的条件下,已成为越来越多火电厂供热改造的首选。针对某电厂2×330 MW高背压抽汽热电联产机组进行建模,分析其理论供热能力,结合热网供回水温度分析其调峰能力与经济性投运条件,研究了采用抽凝-抽背方式(EC-EHBP)、双抽凝方式(EC-EC)运行时的抽汽与负荷分配问题,确定了抽汽分配和电负荷分配原则,明确了不同环境温度下的背压运行方式。研究结果对电厂实际运行具有指导意义。     

高背压双抽热电联产机组联合运行特性及负荷分配

大型汽轮机组采用高背压方式进行供热能够尽可能多利用排汽余热,节能效果显著,在热负荷允许的条件下,已成为越来越多火电厂供热改造的首选。针对某电厂2×330 MW高背压抽汽热电联产机组进行建模,分析其理论供热能力,结合热网供回水温度分析其调峰能力与经济性投运条件,研究了采用抽凝-抽背方式(EC-EHBP)、双抽凝方式(EC-EC)运行时的抽汽与负荷分配问题,确定了抽汽分配和电负荷分配原则,明确了不同环境温度下的背压运行方式。研究结果对电厂实际运行具有指导意义。     

国产300 MW机组深度调峰运行的可靠性和经济性研究

电力工业所面临的是日益加大的峰谷电差,因此就必须加大占全国火电机组装机容量１／３的国产３００ Ｍ Ｗ 机组的调峰任务。外高桥电厂３００ Ｍ Ｗ 机组,在通过１６８ ｈ 试运行后即参与１２０ Ｍ Ｗ的调峰,为国内同类机组提供了良好的经验。     

二连浩特风光互补城市供电示范项目风光互补容量的确定分析

通过对内蒙古二连浩特市年用电负荷及日用电负荷统计分析计算,初步确定二连浩特风光互补城市供电示范项目风光互补容量配置标准方案,即该项目风电场装机容量为72 MW,光伏电站装机容量为22 MW.之后经过风光互补容量配置修正方案分析,22 MW光伏电站发电量可以弥补风电出力低谷时间的用电负荷需求,因此光伏电站装机容量不再调整.根据二连浩特市城市规划及基本用电负荷需求预测,经分析计算,二连浩特地区需要总体配置120 MW风电场和22 MW光伏电站,考虑到二连浩特市已并网运行风电场20 MW、在建风电场50 MW,因此确定该示范项目的风光互补容量配置方案只需配置50 MW风电场及22 MW光伏电站即可,风电场与光伏电站同场同期建设.     

计及市场收益的含储能火电厂日前-日内两阶段优化调度方法

火电厂的市场收益主要包括电能收益与备用收益,机组容量的分配是影响市场收益的重要因素之一,因此提出考虑优化机组容量分配的日前-日内两阶段优化调度方法。分析储能参与电力调度的机理,量化储能可用备用容量,以减小机组爬坡频次、提高机组发电利用率为目标,建立含储能火电厂日前与日内两阶段优化调度模型。采用拉格朗日松弛法对模型进行处理,基于市场边际电价理论求解容量价格与电量价格,并计算火电厂总售电收益。在安装储能与否的两种场景中进行算例分析,结果表明,在火电厂侧安装储能可以有效提高机组发电利用率,增加火电厂收益。     

135MW机组封存保养实践

对135MW机组进行封存保养的情况目前比较少见,随着我国火电机组装机容量的不断增加,将有越来越多更大容量的机组进入封存保养或检修保养状态。通过总结135MW机组的封存保养实践经验,认为对锅炉采用气相缓蚀剂法、对汽机采用干风干燥法能起到较好的封存保养效果。     

Power Sources Planning,Construction and Operation

The year 2000 was a year when China's nationaleconomical and social development witnessed tremendousachievements, and China's electric power industrysuccessfully realized the objectives set at the beginningof the year 2000.In 2000, the nationwide electricity generation fulfilled1368.5TWh, an increase of 10.975% on the basis of year-on-year; the newly commissioned generating capacityreached 20,553 MW. With annual newly commissionedgenerating capacity exceeding 10,000 MW consecutivelyfor thir…     

燃煤电厂水平衡模型与节水分析

随着水资源的日益短缺和火电装机容量的持续增加,应用节水技术是目前火电行业可持续发展的重要途径。基于煤种、气象条件和电厂性能参数,提出了电厂水平衡模型,绘制了电厂水流图,直观体现了进入和离开电厂的水平衡关系,辨析系统节水的关键环节。定量分析了烟气余热及水分回收系统的节能和节水效果。以燃烟煤的超临界机组为例,在离开电厂的水流中,冷却塔蒸发、风吹损失占60%,冷却塔排污占20%,排烟中水分占15%。火电厂节水的重点在于冷却系统、废水排放和排烟水分回收。针对火电厂余热和水分回收的系统,理论计算表明：对于湿冷机组,如果烟气水分回收60%,则超临界机组单位供电量耗水量下降19.2%;对于空冷机组,如果烟气水分回收60%,则电厂的取水量为零;如果同时采用半干法或干法脱硫系统,则电厂可以成为供水方。