GAS TURBINE POWER PLANTS AND ITS SPECIFICATIONS

  INTRODUCTION:

 A combustion turbine, is a type of continuous and internal combustion engine. The basic operation of the gas turbine is a Brayton cycle with air as the working fluid: 

The fourth step of the Brayton cycle (cooling of the working fluid) is omitted, as gas turbines are open systems that do not reuse the same air.

THE THREE MAIN SECTIONS OF A GAS TURBINE:

Figure 1. Gas Turbine

• The compressor which draws air into the engine, pressurizes it, and feeds it to the combustion chamber at speeds of hundreds of miles per hour. 
• The combustion system typically made up of a ring of fuel injectors that inject a steady stream of fuel into combustion chambers where it mixes with the air. The mixture is burned at temperatures of more than 2000 degrees F. The combustion produces a high temperature, high pressure gas stream that enters and expands through the turbine section. 
• The turbine is an intricate array of alternate stationary and rotating aerofoil-section blades. As hot combustion gas expands through the turbine, it spins the rotating blades. The rotating blades perform a dual function: they drive the compressor to draw more pressurized air into the combustion section, and they spin a generator to produce electricity.

TYPES OF GAS TURBINES: 

• Turboprop 
• Turboshaft 
• Aeroderivative 
• Amateur 
• Auxiliary power unit 
• Industrial for power generation 
• Industrial for mechanical drive 
• Radial

TESTING: 

• Selection of the test code to be used is an agreement between the purchaser and the manufacturer and has some significance to the design of the turbine and associated systems. 

Figure 2. Testing

• ASME has produced several performance test codes on gas turbines. This includes ASME PTC 22–2014. These ASME performance test codes have gained international recognition and acceptance for testing gas turbines. 
• The single most important and differentiating characteristic of ASME performance test codes, including PTC 22, is that the test uncertainty of the measurement indicates the quality of the test and is not to be used as a commercial tolerance. 

SIEMENS V94.2 GAS TURBINE

Figure 3. siemens V94.2 gas turbine

• The core engine has a horizontally split casing and two walk-in combustion chambers, equipped with individually replaceable ceramic tiles. This design allows a hot-gas-path inspection without cover lift. The 16-stage axial-flow compressor with variable-pitch inlet guide vanes enhances peak load operation and supports frequency stabilization. 
• The robust 4-stage turbine incorporates the latest blade and vane design for stable, improved performance. The hybrid burners are able to operate in premix and diffusion mode with natural gas, fuel oil and special fuels such as heavy oil and refinery residues. 
• Thanks to its fast start-up capability, you can achieve full load in only about 12 min. With its fast load change capability, in turn, you will meet the most stringent grid requirements for optimal frequency stabilization. 
• offers dual-fuel capability and excellent fuel flexibility: It can be fired with low calorific gases or gases containing CO₂, H₂S and N₂, as well as with crude oil and other liquid fuels with high viscosity. The engine, equipped with DLE burners, is capable to burn up to 30 vol% of hydrogen (H2). 
• NOₓ emissions at 15% O₂ on fuel gas (with DLE) at ISO ambient conditions.

SPECIFICATIONS:

• Output: 187 MW
• Fuel: Natural gas, Distillate oil, Biodiesel,Crude oil, HFO, Kerosene,
• Condensate.
• Frequency: 50 Hz
• Gross Efficiency: 76.5%
• Heat rate: 9863 kg/kWh
• Turbine speed: 3000 rpm
• Pressure ratio: 12.8:1
• Exhaust mass flow: 558 kg/s
• Exhaust Temperature: 536°C

PROVEN DESIGN FEATURES:

•  16/17 Stage compressors – One row adjustable inlet guide vane, fast acting for grid frequency stabilization. 
•  Two large external silo-type combustors - 2x8/2x6 hybrid burners for 50- 60 Hz. 4-stage Turbine. 
•  Built disc-type rotor – Radial coupling and one centre tie rod. 
•  Cold end drive. 
•  Weld design for hot gas casing

THE SIEMENS V94.2 IS SUITABLE FOR THE FOLLOWING APPLICATIONS AND INDUSTRY: 

Figure 4. applications of siemens V94.2 gas turbine

KAWASAKI L30A GAS TURBINE:

Figure 5. kawasaki L30A gas turbine

• The performance characteristics of 5 to 35 MW class industrial gas turbines. 
• With one of the development targets set at an efficiency of 40% or more, the world’s highest in the 20 to 35 MW class gas turbines, which are the most needed, and with the petroleum and gas markets and turbines for mechanical drive units in sight. 
• The L30A gas generator module adopts a multistage axial-flow compressor, a multi-can combustor, and a horizontal split casing structure. 
• For the power turbine module, a ring structure that resists deformation and allows for greater efficiency was designed after proven two-shaft type gas turbines — small-sized gas turbine, the M1F series, and the Super Marine Gas Turbine (SMGT).

Figure 6. Thermal efficiency of generator end vs electric output

FEATURES:

• World’s highest efficiency in 30 MW class gas turbines, the pressure ratio of a compressor used to be about 18, but the L30A achieves 24.5, which dramatically surpasses conventional characteristics. For the compressor, a blade profile optimization tool was applied and, at the same time, inter-stage matching was adjusted via Computational Fluid Dynamics (CFD) across all stages. For the turbine, Kawasaki’s patented technologies for film cooling and conjugate heat transfer and flow (CHT flow) analysis were applied to grasp detailed temperature distributions on turbine blades to improve the design accuracy. 
• Low emission, along with the CO2 emissions reduced through an increase in engine efficiency, the dry low NOx combustor that had produced satisfactory results in the L20A series (third generation) was adopted as design concepts. With a pre-mixing lean-burn type fuel nozzle, three kinds of burners are used to enable Dry Low Emission (DLE) operations across a wide range. 
• Ease of maintenance, the high-temperature section of the gas generator module is structured as a horizontally split casing and a multi-can combustor with the aim of shortening the maintenance time for periodic replacement. In addition, a modular structure design enables easy and fast replacement work in overhauls. 

SPECIFICATIONS: 

• Type: Open cycle, Two-shaft
• Fuel: Natural 
• Gas Output: 30.9 MW 
• Thermal efficiency: 41.3% 
• Compressor: Axial Flow 14 stage 
• Combustor: 8 can 
• Generator turbine, rpm: Axial flow 2 stage, 9330 
• Power turbine, rpm: Axial flow 3 stage, 5600 
• Mass flow rate: 86.5 kg/s 
• Pressure ratio: 24.5 
• Exhaust gas temperature: 470˚C

TECHNICAL DESCRIPTION:

Figure 7. Technical description of kawasaki L30A gas turbine 

CONCLUSION:

• Siemens V94.2 has resulted to be very efficient and robust gas turbine whereas Kawasaki L30 is also efficient but not so strong. 
• Siemens gas turbine can be operated on variety of fuels which makes its very abundant to use but in the case of Kawasaki’ gas turbine can only be operated on natural gas, which makes it limited to a certain application. 
• Siemens and Kawasaki both have vast configuration which helps us to setup it for any heavy operations. 
• Both these turbines are mainly operated at high speeds and temperature which it bulky, expensive and used only where the volume is high. 

Blog Published by :-

1) Upendra Dani-55 ; Mechanical Engineering Department , VIT Pune.

2) Vishwajeet Desai -64; Mechanical Engineering Department , VIT Pune.

3) Nivedita Deshmukh-66; Mechanical Engineering Department , VIT Pune.

4) Swanand Deshmukh-69 ; Mechanical Engineering Department , VIT Pune.

5) Saurabh Dhirde -76; Mechanical Engineering Department , VIT Pune.