Mitsubishi Heavy Industries Technical Review Vol. 50 No. 3 (September 2013)
1Development of 1600°C-Class High-efficiency Gas Turbinefor Power Generation Applying J-Type Technology
MASANORI YURI*1

JUNICHIRO MASADA*2

KEIZO TSUKAGOSHI*3 EISAKU ITO*4SATOSHI HADA*5

Mitsubishi Heavy Industries, Ltd. (MHI) has continued to contribute to the preservation ofthe global environment and the stable supply of energy through gas turbine development based on
our abundant operating experience and state of the art technology. In recent years, usingdevelopment results from the “1,700°C-Class Ultrahigh-Temperature Gas Turbine Component
Technology Development” national project that MHI has participated in since 2004, we havesuccessfully developed and verified the M501J, thereby capable of achieving the world’s first
turbine inlet temperature of 1600°C and a gas turbine combined cycle (GTCC) thermal efficiencyof 61.5% or more. Further based on the core technology employed in the M501J (60Hz unit), MHI
developed the M701J as a 50Hz J unit. M501JAC, in which an air-cooling combustor wasemployed for better operational flexibility, is also under development. This paper presents how
these advanced high-efficiency gas turbines are being developed and operated.

|1. Introduction
Gas turbine-combined cycle (GTCC) power generation, as the highest efficiency and cleanest
power generating system using fossil fuel, also has a high affinity for renewable energy due to its
excellent load ramp rate capability. With the expansion of global demand for electric power andbroadening supply sources of natural gas through actions such as shale gas field exploitation in thebackground, its presence is becoming greater and greater.
For higher GTCC efficiency, a higher temperature of the gas turbine has played an importantrole, and MHI developed the M701D, a 1,150°C-class, large-capacity gas turbine, in the 1980s. Thecompany later developed the M501F with a turbine inlet temperature of 1,350°C in 1989, and theM501G, which employs a steam cooled combustor and has a turbine inlet temperature of 1,500°C
in 1997. Through these developments, MHI has demonstrated high plant thermal efficiency andreliability, as well as low emission (Figure 1). Subsequently, aiming at further higher efficiency,
MHI participated in the national project “1,700°C-Class Ultrahigh-Temperature Gas Turbine
Component Technology Development” to grapple with development of the latest technology
necessary for higher temperature/efficiency and using the results of such development,
developed/demonstrated the capability of M501J to achieve the world’s first turbine inlet
temperature of 1,600°C and GTCC thermal efficiency of 61.5% or more. Furthermore, based on thecore technology used in the M501J (60-Hz unit), M701J was also developed as the 50-Hz unit theJ. The development of M501JAC, in which operational flexibility was improved while maintaining
the same level of performance as the J-type gas turbines by employing an air-cooled combustor inaddition to J type technology, is also under way at the same time.
Table 1 shows gas turbine performance and main specifications. This paper describes how
these state-of-the-art high-efficiency turbines are developed and operated.
*1Manager, Gas Turbine Engineering Department, Power Systems*2Director, Gas Turbine Engineering Department, Power Systems*4

Deputy Director, Gas Turbine Engineering Department, Power Systems*5

Chief Staff Manager, Gas Turbine Engineering Department, Power Systems*3Power Systems

Mitsubishi Heavy Industries Technical Review Vol. 50 No. 3 (September 2013)
2Figure 1

Changing development of turbine models

Table 1 Gas turbine performance (ISO’s standard conditions) and main specifications
60Hz unit
TypeRotating speed
GTCC output(generating-end)
GTCC efficiency(generating-end, on theLHV base)Compressor/pressure ratio
Combustor
Turbine

M501J
3600rpm

M501JAC
3600rpm

50Hz unit
M701J
3000rpm

470MW

450MW

680MW

61% or more

61% or more

61% or more

15 stages/23
Steam-cooled, 16 cans
Air-cooled, 16 cans
Steam-cooled, 22 cans
Row 1-4 rotating blade, air-cooled
Row 1-3 stationary vane, air-cooled
Row 4 stationary vane, non-cooling|2. Development and Verification of M501J Gas Turbines
2.1

Development of M501J gas turbines

The M501J was able to achieve a turbine inlet temperature of 1,600°C through thecompilation of component technologies already demonstrated by the operationally ubiquitous F
type and G/H type, with turbine inlet temperature classes of 1,400°C and 1,500°C, respectively, as
well as through the application of a national project that resulted in the development of the mostadvanced 1,700°C-class technology (Figure 2).

Figure 2

Design concept of M501J gas turbine

Mitsubishi Heavy Industries Technical Review Vol. 50 No. 3 (September 2013)
3The H type shown in Figure 2 is a 1,500°C-class gas turbine that also employs steam coolingin its turbine rotor-stator blades, and has been demonstrated employing a high pressure ratio
compressor with a pressure ratio of 25. This increase in the turbine inlet temperature and theadoption of the latest component technology substantially raises the thermal efficiency comparedwith conventional units, and the M501J can achieve 61.5% or more (ISO’s standard conditions,
low heating value-base) (Table 1). CO2 emissions can be reduced by about 60% if a conventional
coal-fired thermal power plant is replaced by a natural gas-fired J-type combined cycle power
plant. The technical characteristics of the M501J shown in Figure 3 are described in the following:

Figure 3(1)Characteristics of M501J-type gas turbine

Structual design features
The basic structure of the M501J is of the ubiquitous F and G type-based design, and has
inherited characteristics including (a) a connection to the generator using a cold end drive
method that is less affected by thermal elongation and that requires no flexible coupling, etc.,(b) a rotor of the double-bearing structure that is supported by the compressor-side bearing andthe turbine-side bearing, (c) an axial exhaust turbine that is best suited to the layout of a GTCC
plant, and (d) a rotor structure that allows the transmission of the torque by bolt-jointing thetorque pin-clipped disk with the compressor rotor and the curvic coupling-equipped disk withthe turbine rotor.
(2) Compressor
The M501J compressor is a 15-stage axial flow type with a pressure ratio of 23, designedin accordance with the technology of the H-type compressor with a pressure ratio of 25.
Advanced three-dimensional design has been applied for better performance, mitigating theshock loss in the front stage and friction loss in the middle-rear stage. After three-dimensional
CFD-based evaluation, this concept was verified, applying the high-speed research compressor(HSRC, Figure 4) to a real machine-scale model. Air is bled from the three pressure stages –low, middle and high – while the compressor is in operation to control the inlet guide vane
(IGV) and front 3-stage variable vane (VV), thereby limiting the occurrence of rotating stall
while in operation and improving the partial load performance of GTCC.
(3) Combustor
The M501J combustor employs the closed steam cooling method successfully used in theG type. The turbine inlet temperature rose by 100°C from the G type’s 1,500°C to 1,600°C, but
NOx reduction technology was applied, such as lowering the peak flame temperature in thecombustion area through the improvement of combustor nozzle surrounding (Figure 5) for thepurpose of more homogeneous fuel-air mixing, thereby limiting NOx emission concentrations
to a level equivalent to that of the G type. The combustor was verified for its performance andreliability using cold flow, atmospheric pressure rig combustion and high pressure rigcombustion tests, and this was reflected in its detailed design.

Mitsubishi Heavy Industries Technical Review Vol. 50 No. 3 (September 2013)
4

Figure 4 Appearance of high-speed research compressor(HSRC)

Figure 5 Improvement of combustor nozzle(4)Turbine
The turbine is a highly loaded 4-stage axial flow type for high performance. In addition
to the fully three-dimensional design so far employed in the G type for better performance, theturbine aerodynamic technology developed in the national 1,700°C-class gas turbine project
was applied. That is, considering such matters as flow field intervention and the effects of ahorse shoe vortex from the front edge of the blade, we employed a non-axisymmetric endwall
contouring that limits the secondary flow generated on the endwall area. As for the temperatureincrease from the G type, the technology developed in the national project was applied,enabling a conventional equipment-level metal temperature to be maintained. Of the 100°C gas
temperature increase, about 50°C depends on improved turbine cooling technology and about
50°C on advanced thermal barrier coating (advanced TBC) (Figure 6).
Air cooled blades are used for turbine row 1-4 (rotating) blades and row 1-3 (stationary)vanes. Row 4 blade of the G type was an uncooled blade, but the J type’s was cooled due to anincrease in turbine inlet temperature. The blade material employed was MGA1400 (MitsubishiGas Turbine Alloy 1400) for the rotating blades and MGA2400 for stationary vanes, with therow 1-3 rotating blades being of directional solidification. MGA1400/2400 has already been
employed in F and G types.

Figure 6 Component technology to realize turbine inlet
temperature of 1600°C

Mitsubishi Heavy Industries Technical Review Vol. 50 No. 3 (September 2013)
5As shown in Figure 7, the cooling structure has been upgraded each year to the F andthen to the G type, and the J type has, as mentioned earlier, employed high performance filmcooling and advanced TBC as improved turbine cooling technology developed in the nationalproject. As for high performance film cooling, after the film shape was optimized throughcomponent tests of a flat plate (Figure 8) and film efficiency was verified by low-speed
rotating turbine (LSRT) and medium pressure cascade tests, it was employed in the M501G at
T-point and its validity was confirmed. The results of these tests were reflected in the design of
the J type’s turbine blade and the high pressure/hot cascade test was followed by the final test
using the first unit of M501J. Advanced TBC was applied to the T-point M501G turbine blade
and after long-term verification experiments, high pressure/hot cascade tests of the J-typeturbine blades were conducted for verification.

Figure 7 Improvement of turbine cooling structure (Row 1 stationary vane)

Figure 8 Verification of high performance film cooling

2.2

Verification using T-point power generation demonstrator

In the development of the M501J, verification tests were conducted for each component at
the stage of basic design to reflect the results in the detailed design and finally, after verification
experiments using a power generation demonstrator, the commercial unit was manufactured.
Figure 9 shows the appearance of a gas turbine combined cycle power plant demonstrator(T-point) located within the MHI Takasago Machinery Works. At T-point, a combined cycle power
plant equipped with a M501G gas turbine, a steam turbine and a heat recovery steam generator(HRSG) built as a demonstration unit underwent 39,253 hours of operation and 2,301 starts/stops
from January 1997 to October 2010, greatly contributing to the improved performance and higher
reliability of the M501G.

Mitsubishi Heavy Industries Technical Review Vol. 50 No. 3 (September 2013)
6Figure 9

Demonstration facility at MHI Takasago Machinery Works

From October 2010, work to replace the M501G with the M501J was under way and inFebruary 2011, the first M501J unit started trial operation. Trial operation proceeded as scheduled
and after the first spin on February 2, the first ignition on the 7th day of the same month and only 7
starts/stops, the turbine inlet temperature of 1,600°C was reached (Figure 10). Thereafter, various
tests were conducted and overhaul inspections were carried out, and each component and part wasdetermined to be sound. This first unit was subjected to a special 2,300-point measurement,
verifying its performance, mechanical properties and combustion characteristics to satisfy the targetvalues. As an example, Figure 11 shows the blade surface metal temperature distribution of a row
1 stationary vane. With respect to the platform and blade surface of a turbine row 1 rotating blade,the surface metal temperature distribution was measured using a pyrometer. Figure 12 shows ameasurement result of the metal temperature of the rotating blade platform.

Figure 10

T-point demonstrator verification state

Figure 11Turbine Row 1 Stationary vane surface metal temperature measurement results

Mitsubishi Heavy Industries Technical Review Vol. 50 No. 3 (September 2013)
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Figure 12 Turbine row 1 rotating blade platform metaltemperature distribution measured by pyrometer

In addition, the design of gas turbines in recent years features, in addition to component tests
and verification experiments, optimization design to which large-scale analysis including CFD isapplied. These design tools were used effectively not only for the design stage of the M501J, butalso for the analysis of the verification results, and the utilization of such results is reflected in thedevelopment of the high-efficiency gas turbines cited in this paper, greatly contributing to theimprovement of performance and reliability. Figure 13 and Figure 14 show examples ofcompressor/turbine full stage CFD analysis results, and it is apparent that CFD analysis results
reasonably agree with the measurement results.

Figure 13 Full stage CFD analysis and total pressure distribution of actual compressor(Left: Row 5 stationary vane inlet, right: diffuser inlet)

Figure 14 CFD Analysis-measurement comparison of full stage turbine

Mitsubishi Heavy Industries Technical Review Vol. 50 No. 3 (September 2013)
8From July 2011, operation to demonstrate the long-term reliability of M501J was under way
at T-point, reaching 10,548 hours of continuous operation with 120 starts/stops at the end of March2013, and demonstration operation steadily continues. Figure 15 shows the results of major
overhaul inspections in March 2013, where each component and part was found to be sound.

Figure 15 T-point M501J major overhaul inspection results(March 2013, 10548-Hour Continuous Operation, 120 Starts/Stops)|3. J-type technology applied to gas turbine development
Sixteen units of the commercial M501J demonstrated at T-point have been ordered so far,and commissioning of the first commercial unit completed in the summer of 2013 and started thecommercial operation (Figure 16).

Figure 16

Operation schedule

Based on the core technology employed in the M501J, for which excellent performance andhigh reliability were demonstrated, MHI is continually engaged in the development ofhigh-efficiency gas turbines. One of such example is the M701J as the 1,600°C-class J type's 50Hz
unit and the production of its first unit is currently under way. Development of the M501JAC, theoperational flexibility of which was improved by employing an air-cooled combustor, is also takingplace. The characteristics of these high-efficiency gas turbines are described in the following:

3.1

M701J gas turbine

The M701J (rotating speed: 3000rpm, 50Hz) as a scaled version of the M501J (rotatingspeed: 3600rpm, 60Hz) was developed by applying the full-scale design concept with the rpm’s
reciprocal value of 1.2 against 1 as the scale ratio (Figure 17). Namely, with the size of M701J
taken as the 1.2-time scale of the size of M501J, similarity design rules become effective, thus
keeping the stress, temperature and other characteristics of each M701J part similar to those of theM501J. On the other hand, since air flow and output are proportional to the second power of thescale ratio, M701J type’s GTCC output is 680MW, or about 1.44 times that of the M501J (Table1). The shipment of its first unit of the M701J is scheduled in 2014.

Mitsubishi Heavy Industries Technical Review Vol. 50 No. 3 (September 2013)
9Figure 17

3.2

Scale design concept applied to the M701J

M501JAC gas turbine

The M501JAC is a gas turbine which, based on the M501J employing steam cooling for thecombustor, employs the air-cooled combustor successfully used in the M501GAC and offers
improved operational flexibility, such as by shortening the starting time while maintaining the samelevel of performance as that of the M501J (Figure 18).
Figure 19 shows the characteristics of the M501JAC. The compressor is the same as that of
the M501J. The flow pass design of the turbine area is also the same, but the cooling structure of
the turbine rotor/stator blade is optimized in line with the air-cooled combustor employed. The
combustor adopts the air-cooling system successfully used in the M501GAC and the low NOx
technology verified using the J type was applied. The M501JAC is under development aiming at
the first unit shipment in 2015, and in 2014, an air-cooled combustor is expected to undergo
verification with the T-point demonstrator.

Figure 18M501JAC gas turbine design concept

Figure 19Features of M501JAC gas turbine

Mitsubishi Heavy Industries Technical Review Vol. 50 No. 3 (September 2013)10|4. Conclusion
Gas turbine combined cycle (GTCC) power generation is both environmentally andeconomically friendly as the cleanest high-efficiency power generating system using fossil fuel,and is a technology for which society has great hope. Using the results of the “1,700°C-Class
Ultrahigh-Temperature Gas Turbine Component Technology Development” national project thatMHI has participated in since 2004, we have successfully developed/demonstrated the M501J,
which is capable of achieving the world’s first turbine inlet temperature of 1600°C and GTCC
thermal efficiency of 61.5% or more. In addition, based on such core technologies, MHI isproceeding with the development/production of the M701J and M501JAC. These gas turbines,
amid further diversification/decentralization of power sources, will continue to contribute to thestable global supply of electric power as high-efficiency equipment offering both good
performance and operational flexibility.

References
1. 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
2. Hada et al., Test Results of the World's First 1,600C J-series Gas Turbine, Mitsubishi Heavy Industries
Technical Review Vol. 49 No. 1 (2012)
3. Tsukagoshi, K., Evolution of High Temperature and High Efficiency Gas Turbine for Power Generation,and Its Future, GTSJ Vol.41 No.1 (2013-1)
4. Ito, E., CFD Application to Major Component Design and Inlet / Exhaust of the Gas turbine, and theOptimization, GTSJ Vol.40 No.1 (2012-11)