China hosts global ACC meeting to share know-how, innovation

Soon after the Seventh Annual Meeting of the Air-Cooled Condenser (ACC) Users Group in Gettysburg, Pa, Sept 21-24, 2015, industry attention shifted to the International Air-Cooled Condenser Conference in Xi’an, Shaanxi province, China.

Like Gettysburg, the international meeting was a notable venue—in this case the ancient Chinese city with the eminent Tomb of Qin, known for its terracotta warriors and horses. It also is home to the Xi’an Thermal Power Research Institute (TPRI), a primary sponsor and key participant with 25 attendees and focused presentations.

Beyond TPRI, the October 13-16 meeting drew participants from the US, UK, Canada, Netherlands, Germany, Japan, and South Korea. Additional Chinese participants represented power generators, research groups, universities, vendors, and the Chinese affiliates of eight international companies.

China’s expanding power-generation capacity includes more than 100 dry-cooled stations. The conference was organized to share technical information between China and the rest of the world, which has many more ACCs and decades of experience in construction and operation. The most significant information benefiting participants included:

      • Descriptions of current design and operating practices.

      • Problem-solving scenarios and approaches.

      • Innovative applications and future directions for dry cooling.

      • Significance of overlooked operating details.

The meeting opened with welcome addresses by Dr Andrew Howell, chairman of the ACC Users Group (US) and by Lin Weijie, president of TPRI. Keynote reports then discussed direct ACC system developments (China Power Engineering Consulting Group Corp), an industry overview (ACC Users Group), TPRI’s 2015 development plan, and an overview on corrosion and chemistry (Structural Integrity Associates Inc).

Session organization covered condensate polishing, design optimization, operational improvements, corrosion protection, and new technology. Within that structure, TPRI offered specifics on resin separation and transport for mixed-bed polishers, application of pre-coat filters, FAC influencing factors, plate evaporative condensers, and experimental plant operations.  

Meeting content included site-specific discussions on condensate polishing at Dingzhou (Guohua EPRI), ion exchange resins for ultra-supercritical plants (Mitsubishi Heavy Industries Ltd), and ACC commissioning cleaning at Eskom’s Medupi Unit 6 (South Africa).

Other presentations provided insight into measurement and analysis of design data (CPECC), a focus on air-side performance (Howden Group Ltd), chromatography (Thermo Fisher Scientific), current research and application of amines for steam-cycle pH and corrosion control (EPRI), anti-freezing of indirect ACCs (Longyuan Power), a theoretical design called “Lotus Condenser and Hertz” dry cooling (Northwest Electric Power Design Institute), and optimization of internal walkways (Xi’an Jiaotong University).

Some information from the Gettysburg meeting was revised and presented, including updates of guidance documents provided by the International Association for Properties of Water and Steam (IAPWS), examples of low-cost performance improvement (ACC-Team), ACC tube aluminum cladding (Wickeder Group), and hands-on guidance for ACC internal inspections (ACC User Group).

At Gettysburg, a noteworthy new application of ACCs featured the Ivanpah solar project. A similar presentation in Xi’an featured the intent to apply ACCs to new AP1000 nuclear units in China (Electric Power Planning & Engineering Institute).

China ACC Fig 1

Tours of two Huaneng Power International plants completed the meeting: the direct-cooled Tongchuan Power Plant (1200 MW, coal) shown in Fig 1, and the indirect-cooled Qinling Power Plant (2000 MW, coal) shown in Fig 2. The Tongchuan ACC showed the relative design maturity that rapidly has been reached for Chinese ACCs. Basic features are similar to those elsewhere in the world, with minor variations.

China ACC Fig 2

The indirect-cooled ACC design at Qinling has become more common in recent years in China, partly because of efficiency opportunities. This design uses high-purity water in a closed loop that condenses turbine exhaust steam via a typical water-cooled condenser. The cooling water then travels through finned tubes at the base of a natural draft tower.China ACC Fig 3

Energy efficiency is gained by elimination of mechanical fans, and the opportunity for water-enhanced cooling of finned tubes during periods of high ambient temperature. A further item of interest is the routing of flue gas into the natural-draft tower, enhancing air flow as hot flue gas exits the tower (Fig 3).  

The International meeting was sponsored by the China Society for Electrical Engineering (CSEE), TPRI, ACC User Group, CCJ-Online Inc, EPRI, and IAPWS.

According to Howell, who helped organize the event, “Our Chinese hosts did a superb job with all aspects of the meeting, from logistics to technical content. There was excitement on all sides about the opportunities to develop beneficial working relationships for dry cooling in power generation.”

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