1. Basic Knowledge of Gas Turbines

Gas turbines primarily consist of three core components: the compressor, combustion chamber, y turbine. The gas turbine cycle is commonly referred to as a simple cycle, which is the most widely used configuration. However, heavy-duty gas turbines often employ a combined cycle scheme to enhance efficiency. Historically, gas turbines have evolved along different technical paths. Aero-derivative gas turbines, used in industrial and marine applications, are derived from modified aircraft engines. In contrast, heavy-duty industrial gas turbines are developed based on traditional steam turbine concepts and are primarily utilized for mechanical drives and large-scale power generation.

A gas turbine can be visualized as three sections from left to right: the compressor (blue), combustion chamber (red), y turbine (yellow).

2. Classification of Gas Turbines

Globally, dozens of companies are engaged in the research, design, and manufacturing of gas turbines. Currently, the four companies that have fully mastered heavy-duty gas turbine technology are General Electric (GE) of the United States, Siemens of Germany, Mitsubishi Heavy Industries (MHI) of Japan (which initially licensed technology from Westinghouse in the U.S.), and Ansaldo of Italy. According to Mr. Chen Xuewen, Vice Chairman of Shanghai Electric Gas Turbine Co., Ltd., there is no international standard for gas turbine model classification, and the distinctions have become increasingly blurred. Based on available information, gas turbines can be classified as follows:

2.1 Classification by Combustion Temperature (in increments of 100°C):

• General Electric (GE):
  • E-class: 1100°C
  • F-class: 1200°C
  • H-class: 1400°C
• Mitsubishi Heavy Industries (MHI):
  • F-class: 1400°C
  • G-class: 1500°C
  • H-class: Intermediate test product
  • J-class: 1600–1700°C
• Siemens:
  • Older models (V64.3A, V84.3A, V94.3A): 6F-class
  • Newer models (SGT6-5000F, SGT-8000H):
    • F-class: 1200°C
    • H-class: 1500°C

2.2 Classification by Output for Heavy-Duty Gas Turbines:

Heavy-duty gas turbines for power generation are typically classified by output when the combustion temperature ranges between 1100°C and 1500°C:

• Class B: ≤100MW
• Class E: 100–200MW
• Class F: 200–300MW
• Class G/H: 300–400MW

However, as gas turbine outputs have rapidly advanced, this classification method has become somewhat outdated.

3. Development of International Gas Turbines

Siemens:

El SGT5-8000H super gas turbine is a flagship product, weighing 390 tons (equivalent to a fully fueled Airbus A380) and measuring 13.1 meters in length, 4.9 meters in width, and 4.9 meters in height. With a combined cycle power output of 595MW, it can supply electricity to a large industrial city. Its turbine blades endure temperatures exceeding 1500°C, surpassing the turbine inlet temperatures of the GE90 turbofan and F404 jet engines. The blade tip speed exceeds 1700 km/h, subjecting each blade to centrifugal forces equivalent to 10,000 times Earth’s gravity. Manufacturing tolerances are within tens of microns, as even minor flaws can render a blade unusable. It is often said that a single blade is worth the value of a BMW.

Mitsubishi Heavy Industries (MHI):

El M701J super gas turbine, with a combined cycle power output of 650MW, features a 15-stage axial compressor with a pressure ratio of 23:1. The burner and 4-stage axial turbine are air-cooled, with the first three stages incorporating advanced technologies such as high-temperature protective coatings, ceramic thermal barrier coatings, y high-performance air film cooling. With a turbine inlet temperature of 1600°C, it ensures the longevity of high-temperature components. The J-series innovations focus on reducing carbon emissions. In March 2020, MHI received an order for two M501JAC powertrains from the Intermountain Power Authority in Utah, USA. These turbines utilize an air-cooled dry low-NOx combustion system and can operate on up to 30% renewable hydrogen fuel. Compared to coal-fired plants of similar capacity, the 30% hydrogen system reduces carbon emissions by over 75%, while a 100% hydrogen system eliminates carbon emissions entirely. The plant aims to achieve 100% renewable hydrogen electricity generation between 2025 and 2045.

General Electric (GE):

El 9HA series of heavy-duty gas turbines are the most efficient combined cycle gas turbines globally. The latest 9HA.02 model boasts a combined cycle efficiency exceeding 64% and a power output of 826MW, surpassing its competitors. GE employs cutting-edge 3D printing technology to manufacture key components, further enhancing performance and reliability.

Conclusión

The gas turbine industry continues to advance, driven by innovations in materials, cooling technologies, and combustion systems. Companies like Siemens, Mitsubishi Heavy Industries, and General Electric are leading the way with turbines that offer unprecedented efficiency, power output, and environmental sustainability. These advancements not only meet the growing demand for energy but also align with global efforts to reduce carbon emissions and transition to cleaner energy sources.