地热资源发电技术特点及发展方向

地热资源是一种清洁无污染、可再生的新型能源,对于发展低碳经济、实现可持续发展具有积极的作用.目前地热发电技术主要包括干蒸汽发电、扩容式蒸汽发电、双工质循环发电和卡琳娜循环发电等.其中干蒸汽发电系统工艺简单,技术成熟,安全可靠,循环效率可达20％以上,是高温地热田发电的主要形式；扩容式发电技术已在地热发电领域得到广泛应用,尤其是中高温地热田,二级扩容系统循环效率约为15％～20％；针对中低温地热资源,双工质循环发电技术是较为适用的,它由地热水系统和低沸点介质系统组成,循环效率较扩容式蒸汽发电技术可提高20％～30％;卡琳娜循环在低温地热资源应用领域中有其独特的优越性,通过调整氨和水的比例,可以适应低温地热水的发电特性,卡琳娜循环发电技术的循环效率比朗肯循环的效率高20％～50％.在低温地热资源的开发利用过程中,双工质循环和卡琳娜循环技术具有广阔的发展前景.作为一种新型地热资源,干热岩具有很高的开发利用价值.新型的联合循环发电技术是地热发电技术的发展方向.在浅层地热能得到大规模开发后,中深层地热资源和干热岩资源将成为地热发电技术新的资源,我国应注重中深层地热资源和干热岩资源的开发.

Characteristics of Geothermal Resource-based Power Generation Technology and Development Trends

Geothermal resources are clean,green and renewable energy sources and could play an important role in promoting China′s effort to develop low-carbon economy and achieving sustainable growth.The main geothermal resource-based power generation techniques currently available include dry steam power generation,expansion-type steam power generation,dual-working medium cycle power generation and Kalina cycle power generation.The dry steam power generation technology is characterized by simple process,proven technology and high safety and reliability.Its cycle efficiency could exceed 20%.This technology is the main form of high-temperature geothermal field power generation.The expansion-type power generation technology has been widely used in geothermal resource-based power generation.Particularly in high and medium-temperature geothermal fields,the cycle efficiency of a secondary expansion-type system reaches some 15%-20%.For low and medium geothermal resources,the dual-working medium cycle power generation technology is more appropriate.This technology consists of a geothermal water system and a low-boiling point medium system.The cycle efficiency of this technology is 20%-30% higher than that of the expansion-type steam power generation technology.The Kalina cycle has unique superiority in low-temperature geothermal applications.The technology can meet the requirements for power generation using low-temperature geothermal water.The efficiency of the Kalina cycle is 20%-50% higher than that of the Rankine cycle.In the development and utilization of low-temperature geothermal resources,the dual-working medium cycle and the Kalina cycle have bright prospects for further development.As a new type of geothermal resource,hot dry rock has high potential to become commercially viable development.Innovative combined cycle power generation technology is the development trend for geothermal power generation.After shallow geothermal resources are developed on commercial scale,geothermal and dry hot rock resources buried in medium and deep formations will become the new resources for geothermal power generation.Therefore,China should put a premium on the development of geothermal and dry hot rock resources in medium and deep formations.