Mitsubishi Heavy Industries Technical Review Vol. 58 No. 3 (September 2021)

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Operation Status of 1650°C Class M501JAC Gas Turbine
at T-point 2 Power Plant Demonstration Facility

KAZUKI MORIMOTO*1

YOSHIKAZU MATSUMURA*2

KENTARO SUZUKI*1

SUSUMU WAKAZONO*3

MASAHITO KATAOKA*4 MASANORI YURI*5

Renewable energy has become more widespread in recent years. At the same time, theimportance of gas turbine combined cycle (GTCC) power generation has also been on the risebecause of the power supply instability of renewable energy. For higher GTCC efficiency, a higher
temperature of the gas turbine is important. Mitsubishi Power, Ltd. (Mitsubishi Power) developed
the high-efficiency M501J gas turbine, which attained the world’s first turbine inlet temperature of
1600°C, utilizing the development results from the “1700°C class Ultrahigh-Temperature Gas
Turbine Component Technology Development” national project in which it has participated since2004. We have since steadily accumulated operating results. At T-point 2 in January 2020, we
started test operation of the next-generation 1650°C class JAC series gas turbine, which is basedon the proven J series and uses an enhanced air-cooled system for cooling the combustor, a thicker
TBC (thermal barrier coating) and a compressor with a high pressure ratio as its coretechnologies, all of which have been validated as individual elements at the T-point demonstration
facility. The final confirmation of the integrity of equipment reliability, performance, etc., wascompleted and commercial operation started in July 2020. This report presents the verification
results of the test operation and the operation status thereafter.

|1. Introduction
Since it has recently become very important to reduce CO2 emissions, power supply by
renewable energy sources such as wind power generation and solar photovoltaic power generation
has been planned and carried out. However, such renewable energy sources are unstable andnatural fluctuations are unavoidable and present concerns such as sudden frequency and load
fluctuations in the power system. Against this background, GTCC power generation, which is more
efficient and more operable than conventional thermal power generation, is becoming more
important in terms of global environmental conservation and a stable energy supply. For higher
GTCC efficiency, a higher temperature of the gas turbine plays an important role. We developed
the M701D, a 1150°C class large-capacity gas turbine, in the 1980s. This was followed by the
M501F, which had a turbine inlet temperature of 1350°C and the M501G, which employed asteam-cooled combustor and had a turbine inlet temperature of 1500°C (Figure 1). Through thesedevelopments, we have verified the high plant thermal efficiency and reliability, as well as low
emissions. From 2004, we participated in the “1700°C class Ultrahigh-Temperature Gas Turbine
Component Technology Development” national project to conduct research and development of thelatest technology necessary for higher temperature and efficiency and utilized the results of these
*1
*2
*3
*4
*5

Large Frame Gas Turbine Engineering Department, Gas Turbine Technology & Products Integration Division, Mitsubishi
Power, Ltd.
Chief Staff Manager, Large Frame Gas Turbine Engineering Department, Gas Turbine Technology & Products Integration
Division, Mitsubishi Power, Ltd.
Manager, Large Frame Gas Turbine Engineering Department, Gas Turbine Technology & Products Integration Division,
Mitsubishi Power, Ltd.
Director, Large Frame Gas Turbine Engineering Department, Gas Turbine Technology & Products Integration Division,
Mitsubishi Power, Ltd.
Senior General Manager, Gas Turbine Technology & Products Integration Division, Mitsubishi Power, Ltd.

Mitsubishi Heavy Industries Technical Review Vol. 58 No. 3 (September 2021)

efforts to develop the M501J, which attained the world’s first turbine inlet temperature of 1600°C.
Verification operation of the M501J GTCC started in 2011 at the gas turbine combined cycle power
plant demonstration facility (T-point) located in Mitsubishi Power Takasago Works and operating
results have been steadily accumulated.
The J series gas turbine adopts a steam-cooled system for cooling the combustor, but if an
air-cooled system can be used while maintaining the high turbine inlet temperature, further
improvement in the efficiency and operability of GTCC is expected. Therefore, we worked on thedevelopment of next-generation GTCC that realizes air cooling of high-temperature gas turbinesand devised the enhanced air-cooled system that is one of its core technologies. In the spring of
2015, we completed the validation test of the entire system at T-point and since then the system has
been in operation for more than 10,000 hours. This core technology is applied to thenext-generation high-efficiency JAC (J-Air-Cooled) series gas turbine, which has achieved a highturbine inlet temperature of 1650°C. We have been proceeding with the construction of the second
gas turbine combined cycle power plant demonstration facility (hereinafter referred to as T-point 2)
located in Mitsubishi Power Takasago Works for long-term actual-equipment validation of the JAC
series gas turbine. T-point 2, which is state-of-the-art GTCC equipment with an output of 566 MW
that combines the 1650°C next-generation JAC high-efficiency gas turbine and the
newly-developed high-efficiency steam turbine, has been in test operation since January 2020 andachieved a combined rated output of 566 MW on April 2. We then carried out various tests andadjustments necessary to operate T-point 2 as a power plant, completed all the functional
confirmations and started commercial operation on July 1. Due to the adoption of the JAC series
gas turbine, the power generation efficiency of the GTCC reached 64%. During test operation, inorder to verify the underlying technology, we carried out thousands of temporary large-scalemeasurements in addition to those provided by regular measurement instruments and monitored
and evaluated them online. This report presents the development concept of the state-of-the-art
high-efficiency JAC series gas turbine, the verification results obtained at the T-point 2
demonstration facility and the operation status including commercial operation for about one year
thereafter.

Figure 1

Developmental trend of large gas turbine models|2. Development concept of 1650°C class M501JAC gas turbine
We proceeded with the development of the next-generation 1650°C class JAC series gas
turbine in order to further improve the efficiency and operability by applying to the proven M501J
gas turbine the following validated component technologies: (1) an enhanced air-cooled system forcooling the combustor, (2) a thicker TBC and (3) a compressor with a high pressure ratio.
The basic concept of this gas turbine is as follows (Figure 2 and Figure 3). Validation ofthese individual component technologies was completed at the T-point demonstration facility and2Mitsubishi Heavy Industries Technical Review Vol. 58 No. 3 (September 2021)

they were then applied to the 1650°C class JAC series gas turbine (Table 1).
(1) Adopting an enhanced air-cooled system to improve operability and increase the turbine
inlet temperature in comparison to that of the J series.
(2) Adopting a thicker TBC developed based on the technology resulting from the national
project to achieve both high performance and reliability despite the increased turbine inlet
temperature.
(3) Adopting a compressor with a high pressure ratio design equivalent to the M501H (validated
from 1999 to 2000, hereinafter referred to as the H series) to suppress the increase in theexhaust gas temperature at the gas turbine outlet.

Figure 2

Development concept of 1650°C class JAC gas turbine

Figure 3

Application flow of component technology to 1650°C class JAC gas turbine3

Mitsubishi Heavy Industries Technical Review Vol. 58 No. 3 (September 2021)

Table 1Comparison of gas turbine performance(ISO, standard conditions)
M501J

M501JAC

Frequency (Hz)60

60

Pressure ratio (-)

23

25

Gas turbine output (MW)

330

435

Gas turbine efficiency (%-LHV)

42

44

Combined cycle output (MW)

484

630

Combined cycle efficiency (%-LHV)

62

>64

|3. Verification results and operation status of the 1650°C class
M501JAC gas turbine at T-point 2
T-point 2 is a state-of-the-art GTCC facility with an output of 566 MW that combines a
1650°C next-generation high-efficiency JAC series gas turbine and a newly-developed
high-efficiency steam turbine. The M501JAC gas turbine was shipped and installed in the spring of2019 and test operation at T-point 2 commenced in January 2020. In this test operation, first the gas
turbine alone was operated and reached its rated load after 10 starts from the first ignition. After
steam ventilation, the operability confirmation test was carried out by Combined Cycle (CC)operation and commercial operation began on July 1 (Figure 4 and Figure 5). In test operation, weconstantly monitored the start-up acceleration, no-load rated speed and state quantity during
partial-load and rated-load operation of the gas turbine in order to make a final confirmation of thereliability, actual performance, exhaust gas emissions, etc., of the equipment. Next, functional tests
and special tests required for actual commercial plants were completed.

Figure 4

Test operation schedule at T-point 2

Figure 5

Overview of T-point 2 combined cycle plan4

Mitsubishi Heavy Industries Technical Review Vol. 58 No. 3 (September 2021)

During test operation, more than 2,800 temporary large-scale measurements were conducted
to evaluate the integrity in order to verify the technologies that are the basis of the JAC series gas
turbine. For the rotating parts, roughly 100 large-scale telemetric measurements were carried out toconfirm the metal temperature and vibration stress integrity of the compressor rotors and turbine
blades. This chapter presents the final confirmation results of the integrity of each component(Figure 6), as well as the status following the commercial operation verification test run overapproximately one year after the final integrity confirmation observed in the inspection during aplanned stop in March 2021.

Figure 6

Implementation status of test operation and temporary measurements

3.1 Enhanced air-cooled combustor and enhanced air-cooled system

The enhanced air-cooled system had already been validated at the T-point demonstration
facility, including its ability to follow transient changes. In addition, the metal temperature of theenhanced air-cooled combustor was measured in this test operation and its cooling performance inthe actual equipment was ultimately validated. As a result, it was confirmed that the combustion
casing metal temperature distribution was lower than the design allowance value, so there were no
problems in terms of cooling performance (Figure 7). It was also confirmed that there were no
particular problems with the combustion vibration characteristics and exhaust gas emissions andstable operation was possible under partial-load to rated-load conditions.
The JAC series gas turbine uses a system that enables clearance control during under-load
operation based on the enhanced air-cooled system. This system uses two cooling air supply
methods: one causes cooling air to bypass the turbine blade ring and introduces it directly into the
combustor and the other causes cooling air to pass through the turbine blade ring in advance tosupply it to maximize the performance by reducing the turbine clearance during load operation.
These two systems can be switched by the switching valve (three-way valve) even during load
operation. The former can handle operation with large load fluctuations by opening the clearance(Flexible Mode). On the other hand, the latter can close the clearance during load-hold operationand maximize the performance of steady operation (Performance Mode). Figure 8 shows the
behavior of the clearance when the three-way valve is switched during load operation. It was
ultimately confirmed that this system can improve operability more than before while maximizing
performance.

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Mitsubishi Heavy Industries Technical Review Vol. 58 No. 3 (September 2021)

Figure 7

Measurement results of enhanced air-cooled combustor metal temperature

Figure 8

Turbine clearance control using enhanced air-cooled system

3.2 Turbine blade metal temperature

The turbine inlet temperature of the 1650°C class JAC series gas turbine can become 50°C
higher than that of the J series and adopts a thicker TBC to achieve both high performance andreliability. As mentioned above, the integrity of the thicker TBC has been verified and confirmed atT-point over the long term. Figure 9 shows the specially-measured metal temperature distributionof the JAC series turbine row 1 vane to which the TBC is applied in order to optimize the coolingdesign. It was confirmed that although the turbine row 1 vane was subjected to the strictest heatload and its cooling structure was complicated, there were no local high temperature parts, all parts
were below the design allowance temperature and the integrity was maintained under the conditionof an inlet gas temperature of 1650°C. The integrity was also confirmed in the inspection after
operation.

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Mitsubishi Heavy Industries Technical Review Vol. 58 No. 3 (September 2021)

Figure 9 Metal temperature distribution measurement results of turbine row 1 vane andinspection results after operation

For the turbine row 1 blade, in addition to confirmation of the blade surface metal
temperature and vibration stress using telemetric measurements, pyrometric measurement, which
has been introduced at T-point, was carried out. The pyrometer was inserted into the gas path fromthe standby position through the insertion hole provided in the combustor casing and the turbine
row 1 vane to confirm the integrity of the blade surface temperature distribution around the leadingedge of the blade surface, which was subjected to a particularly high heat load. The integrity was
also confirmed in the inspection after operation (Figure 10).

Figure 10 Surface temperature distribution measurement results of turbine row 1
blade and inspection results after operation

3.3 High pressure ratio compressor

The compressor of the 1650°C class JAC series gas turbine has a pressure ratio that wasincreased from 23 to 25. However, since a high pressure ratio compressor has a design in which theoutlet flow path area is relatively narrow, there is a concern that the flow rate will decrease and therotating stall will relatively deteriorate during startup with a low pressure ratio. As mentioned
above, an H series compressor with a similar pressure ratio of 25 was validated, as was acompressor with a pressure rate of 25 based on the J series in May 2018 at T-point. Detailed
temporary measurements were also carried out for the JAC series and it was ultimately confirmedthat the starting characteristics, blade vibration stress and aerodynamic performance were favorable(Figure 11).

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Mitsubishi Heavy Industries Technical Review Vol. 58 No. 3 (September 2021)

Figure 11 Verification results of JAC gas turbine high pressure ratio
compressor

3.4 Status of gas turbine after one year of operation

Commercial operation commenced on July 1, following the test operation that started in
January 2020. It has been confirmed that the components are sound after about one year of power
supply operation and verification test operation, as a result of inspection of various parts including
the compressor, combustor, turbine and inlet/exhaust systems and thus there is no problem in termsof the long-term reliability (Figure 12). After the completion of the verification test operation in
the spring of 2021, power supply operation will be continued again and operational hours and thenumber of starts will be further accumulated to continuously confirm the long-term reliability.

Figure 12

Overview of JAC series gas turbine inspection results in March 2021

3.5 Future development of JAC series gas turbine

As shown below, the construction and operation of customers' commercial plants using JAC
series gas turbines that have been verified at our power plant demonstration facility T-point 2 andconfirmed to offer long-term reliability as described above have commenced, striving steadily forrealizing a more stable global energy supply. 60 Hz M501JAC gas turbines have been shipped tocommercial plants in North America and other countries one after another since September 2020
and the local installation work is being carried out (Figure 13). The first of the eight 50 Hz
M701JAC gas turbines for Thailand started operation on March 31, 2021, as scheduled despite the
COVID-19 disaster. The construction work of the remaining units is progressing toward the start ofoperation of all turbines in 2024 (Figure 14).

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Mitsubishi Heavy Industries Technical Review Vol. 58 No. 3 (September 2021)

Figure 13

Shipping of commercial 60 Hz M501JAC gas turbine

Figure 14

Operation start of commercial 50 Hz M701JAC gas turbine|4. Conclusion
For higher GTCC efficiency, a higher temperature of the gas turbine plays an important role.
Mitsubishi Power has participated in the “1700°C class Ultrahigh-Temperature Gas Turbine
Component Technology Development” national project since 2004. We utilized the results of these
efforts to develop the high-efficiency M501J gas turbine, which attained the world’s first turbine
inlet temperature of 1600°C and we have since steadily accumulated operating results. In order tofurther improve the efficiency and operability of GTCC, we developed the next-generation 1650°C
class JAC series gas turbine, which is based on the proven J series and uses an enhanced air-cooledsystem for cooling the combustor, a thicker TBC and a compressor with a high pressure ratio as itscore technologies and completed the validation of the individual elements at the T-point
demonstration facility.
We had been proceeding with construction of the second gas turbine combined cycle power
plant demonstration facility (T-point 2) at our Takasago Works for long-term verification of the
JAC series gas turbine. We started its test operation in January 2020, carried out as many as about
2,800 temporary large-scale measurements and made final confirmation of the integrity of the JAC
series components, such as the reliability and performance during 1650°C operation. At T-point 2,
the combined rated output reached 566 MW on April 2 and all the functional confirmations as a
power generation facility were completed. Commercial operation commenced on July 1. Since
then, both operational hours and number of starts continue to be accumulated in the operationaccording to the supply and demand requirements. It has been confirmed that the components after
about one year of operation are sound and that they offer long-term high reliability.
Verified M501JAC gas turbines have been shipped to commercial power plants in North
America, etc., one after another and the 50 Hz M701JAC gas turbine also started operation in
Thailand in March 2021 as scheduled despite the COVID-19 disaster. Hydrogen co-firing isplanned for a future GTCC power generation project in Utah in the United States. By incorporating
our proprietary combustor technology, we aim to start the operation of the JAC series gas turbinewith a hydrogen co-firing rate of 30% and to realize 100% hydrogen-fired operation in the future.
The long-term verification operation at T-point 2 is carried out from our RMC (remotemonitoring center). We aim to improve the reliability of not only major equipment such as gas
turbines, but also the entire plant including auxiliary equipment, validate various applications

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included in the “TOMONI” digital solution, such as shortening the startup time and automatically
optimizing operating parameters and realize autonomous operation in the future.

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Takamura, Wakazono, Yuri, et al., Development of 1650℃ Class Next Generation JAC Gas Turbine
based on J Experience, Mitsubishi Heavy Industries Technical Review Vol.56 No.3 (2019)(3) Morimoro, Wakazono, Yuri, et al., Validation Results of 1650°C Class JAC Gas Turbine at T-point 2
Demonstration Plant, Mitsubishi Heavy Industries Technical Review Vol.58 No.1 (2021)(4) Matsumi, Kawamura et al., MHPS’s Gas Turbine Technologies for Rapid Load Change, GTSJ Vol.47
No.1 (2019.1)(5) Hada, S., Masada, J., Ito, E. and Tsukagoshi, K., Evolution and Future Trend of Large Frame Gas Turbine
for Power Generation - A new 1600 degree C J class gas turbine -, ASME Turbo Expo, GT2012-68574(6) Hada, Yuri, et al., High-efficiency Gas Turbine Development applying 1600°C class "J" Technology,
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