Advanced Humid Air Turbine System Research Articles

Part-load performance modelling of a reheated humid air turbine power cycle

Humid air turbines have previously demonstrated the potential to deliver high efficiency and power output combined with low emissions. This paper investigates the part-load performance of a 40 MW class advanced humid air turbine for power generation applications across a range of operating conditions. The paper investigates the impact of the main burner and reheater burner on the system’s part-load power output and thermal efficiency and provides insights into the behavior of the key modules across the power spectrum of operation including the saturator tower which was never reported previously. The impact of the ambient air and sea water temperature on the cycle’s performance are also investigated. The outcome of the research shows that the thermal efficiency if the system is less than 0.26% penalized when operating down to 50% of the design power output. Sea water temperature was found to have a more notable impact than ambient air temperature on both power output and thermal efficiency Overall, this work constitutes a step ahead in understanding the potential benefits of an advanced humid air turbine system for power generation applications across a range of operating conditions which is not previously shown.

C204 高湿分空気利用ガスタービンシステムの40MW級総合試験(OS7 高温・高効率発電)

A 40MW-class AHAT (Advanced Humid Air Turbine) test facility was built and rated output was achieved Through operations at this facility, it has been verified for the first time that the key components of the medium-class gas turbines, such as an axial compressor and multi-can combustor, can be applied to the AHAT system. The cold start-up time from ignition to rated power was about 60 minutes, which is approximately one-third that of a gas turbine combined cycle plant. NO_x concent ration was 24ppm (at 16% O2) when the humidity of combustion air was approximately a half of the commercial AHAT plant, and an outlook of achieving NO_x concentration of less than l0ppm was achieved for the commercial plant. Through continued operations at this facility, further tests to confirm operating characteristics under various conditions and component reliability will be conducted to assess system characteristics of commercial AHAT equipment.

Experimental and Analytical Study on the Operation Characteristics of the AHAT System

Operational flexibility, such as faster start-up time or faster load change rate, and higher thermal efficiency, have become more and more important for recent thermal power systems. The advanced humid air turbine (AHAT) system has been studied to improve operational flexibility and thermal efficiency of the gas turbine power generation system. Advanced humid air turbine is an original system which substitutes the water atomization cooling (WAC) system for the intercooler system of the HAT cycle. A 3 MW pilot plant, which is composed of a gas turbine, a humidification tower, a recuperator and a water recovery system, was built in 2006 to verify feasibility of the AHAT system.In this paper, ambient temperature effects, part-load characteristics and start-up characteristics of the AHAT system were studied both experimentally and analytically. Also, change in heat transfer characteristics of the recuperator of the 3 MW pilot plant was evaluated from Nov. 2006 to Feb. 2010. Ambient temperature effects and part-load characteristics of the 3 MW pilot plant were compared with heat and material balance calculation results. Then, these characteristics of the AHAT and the combined cycle (CC) systems were compared assuming they were composed of mid-sized industrial gas turbines.The measured cold start-up time of the 3 MW AHAT pilot plant was about 60 min, which was dominated by the heat capacities of the plant equipment. The gas turbine was operated a total of 34 times during this period (Nov. 2006 to Feb. 2010), but no interannual changes were observed in pressure drops, temperature effectiveness, and the overall heat transfer coefficient of the recuperator.

E113 高湿分空気利用ガスタービンの大気温度特性と部分負荷特性(OS6 高温・高効率発電),動力エネルギーシステム部門20周年,次の20年への新展開)

E113 高湿分空気利用ガスタービンの大気温度特性と部分負荷特性(OS6 高温・高効率発電),動力エネルギーシステム部門20周年,次の20年への新展開)

C220 3MW級高湿分空気ガスタービンAHATのシステム検証試験(ガスタービンその他,OS7 高温・高効率発電)

The Advanced Humid Air Turbine (AHAT) system improves the gas turbine thermal efficiency by using high-humidity air without needing a high firing temperature and pressure ratio. A system verification plant that consists of a gas turbine generator (two-stage radial compressor with pressure ratio 8, two-stage axial turbine, single-can combustor), recuperator, humidification tower, water recovery system, and other components was constructed to validate performance of AHAT system. The verification test has been begun since October 2006. The test results showed good performance such as thermal efficiency over 40 %(LHV) and NOx emissions less than 10 ppm.

Development of Elemental Technologies for Advanced Humid Air Turbine System

The advanced humid air turbine (AHAT) system improves the thermal efficiency of gas turbine power generation by using a humidifier, a water atomization cooling (WAC) system, and a heat recovery system, thus eliminating the need for an extremely high firing temperature and pressure ratio. The following elemental technologies have been developed to realize the AHAT system: (1) a broad working range and high-efficiency compressor that utilizes the WAC system to reduce compression work, (2) turbine blade cooling techniques that can withstand high heat flux due to high-humidity working gas, and (3) a combustor that achieves both low NOx emissions and a stable flame condition with high-humidity air. A gas turbine equipped with a two-stage radial compressor (with a pressure ratio of 8), two-stage axial turbine, and a reverse-flow type of single-can combustor has been developed based on the elemental technologies described above. A pilot plant that consists of a gas turbine generator, recuperator, humidification tower, water recovery system, WAC system, economizer, and other components is planned to be constructed, with testing slated to begin in October 2006 to validate the performance and reliability of the AHAT system. The expected performance is as follows: thermal efficiency of 43% (LHV), output of 3.6MW, and NOx emissions of less than 10ppm at 15% O2. This paper introduces the elemental technologies and the pilot plant to be built for the AHAT system.

F207 ガスタービン翼の高湿分冷却試験(OS-7 高温・高効率発電(1),一般講演,地球温暖化防止と動力エネルギー技術)

Experiments of gas turbine blades cooled by high-humidity air were performed to examine the effect on reducing cooling air for AHAT(Advanced Humid Air Turbine) system. Two types of hybrid cooling structure using dry air and high-humidity air as a coolant were considered. A hot wind tunnel was used to realize the real combustion gas condition. The experimental result shows this hybrid cooling structure has high cooling effectiveness compared with the conventional cooling structure.

Design Study of a Humidification Tower for the Advanced Humid Air Turbine System

The advanced humid air turbine (AHAT) system, which can be equipped with a heavy-duty, single-shaft gas turbine, aims at high efficiency equal to that of the HAT system. Instead of an intercooler, a WAC (water atomization cooling) system is used to reduce compressor work. The characteristics of a humidification tower (a saturator), which is used as a humidifier for the AHAT system, were studied. The required packing height and the exit water temperature from the humidification tower were analyzed for five virtual gas turbine systems with different capacities (1, 3.2, 10, 32, and 100MW) and pressure ratios (π=8, 12, 16, 20, and 24). Thermal efficiency of the system was compared with that of a simple cycle and a recuperative cycle with and without the WAC system. When the packing height of the humidification tower was changed, the required size varied for the three heat exchangers around the humidification tower (a recuperator, an economizer, and an air cooler). The packing height with which the sum total of the size of the packing and these heat exchangers became a minimum was 1m for the lowest pressure ratio case, and 6m for the highest pressure ratio case.

高湿分空気利用ガスタービンの検討 : (1)性能評価(FP1 高温・高効率発電・エネルギー貯蔵技術)

This paper describes advanced utilization of moisture in gas turbine systems for the purpose of improving thermal efficiency and output. We have proposed and been developing AHAT(Advanced Humid Air Turbine) system. The AHAT system is a system which uses existing mutual technologies and aims highperformance equal to that of the HAT system. Comparative calculations results on the small-scale AHAT system are presented. All results are evaluated by the in-house heat cycle simulator, which performs mass and energy balancing based on enthalpy calculations. As a result, AHAT system has 1.27 times larger output and 1.63 times higher thermal efficiency than the simple cycle system. The possibility of remodeling a gasturbine designed for AHAT system (recuperative or simple cycle system) for use in other systems is also examined. As a result, a gas turbine designed for AHAT system is available for use in recuperative or simple cycle system.

高湿分空気利用ガスタービンの検討 : (2)加湿方法とシステム性能(FP1 高温・高効率発電・エネルギー貯蔵技術)

The characteristic of a saturator (a humidification tower), which is used as a humidifier of the AHAT( Advanced Humid Air Turbine) system, were studied. For various pressure ratios (from 8 to 24) of a gas turbine, the required packing height and the exit water temperature from the saturator were analyzed. Thermal efficiency of the system was compared with the simple cycle and the recuperated cycle. The highest thermal efficiency of the system was 54.7% LHV when the pressure ratio was 20. The efficiency can be raised further by cooling blades with humid air. When the packing height of the saturator was changed, the required size of three heat exchangers around the saturator (a recuperator, an economizer and an air cooler) varied. The packing height with which the sum total of the size of the saturator and these heat exchangers become the minimum was 1m when the pressure ratio was 8, and 6m when the pressure ratio was 24.

1007 アドバンスト高湿分ガスタービン用拡散燃焼器の実験的検討

In this work, an experimental study is carried out to obtain the combustion characteristics of a diffusion flame combustor used under high humidity condition of the advanced humid air turbine (AHAT) system. Low flame temperature caused by high humidity condition is expected to decrease NOx emission, but it may weaken flame stability. The influence of humidity on NOx emission and flame stability is studied with combustion test using three types of combustor with different axial distribution of combustion air. The flame stability of diffusion flame combustor is enough for AHAT operation. NOx emission of the combustor with local humidification is 10ppm at 16.8wt% of humidity. The result shows that it is possible to cope with both flame stability and NOx reduction in AHAT system.

D203 高湿分空気利用ガスタービン発電システム

This paper describes advanced utilization of moisture in gas turbine system for the purpose of improving efficiency and output. We have proposed and been develping a concept of Advanced Humid Air Turbine (AHAT) system. In AHAT system, unlike the original HAT system which used inter-cooling type compresser, water atomization cooling (WAC) is used to cool the suction air. More water is added between compresser and recuperator to increase recuperated heat and turbine output. Heat cycle evaluation has shown that the optimum pressure ratio to AHAT is close to that of heavy duty gas turbines. The evaluation also revealed that efficiency of AHAT exceeds combined cycle and the difference is greater in small unit.