The Benefits of Combustion Gas Turbines (CGT)
Combustion gas turbines are a great choice for utility plants as they can provide both base and peak loads. With a wide range of power available from fractional megawatts to hundreds of megawatts, CGTs offer a high power-to-weight ratio, are compact and fuel-flexible, and require no cooling water. Additionally, they can be used for combined cycle and cogeneration, and have a minimum environmental impact due to combustion at very lean conditions.
Types of CGT
Gas turbines can be classified according to their application or design. For application, they can be micro gas turbines, aero-derivatives, industrial gas turbines, and heavy-duty gas turbines. Regarding design, CGTs are single-shaft and two-shaft turbines, which eliminates the need for a gearbox, and are suitable for driving compressors and pumps.
Performance Factors
Gas turbine performance is affected by a variety of factors, including ambient conditions, installation, and ISO conditions. Inlet air chilling of the air going to the CGT compressor can enhance power output and heat rate due to the increase in density and mass flowrate to the constant volume CGT machine.
Advantages and Disadvantages of CGT
The advantages of CGT include a wide power range, high power-to-weight ratio, fuel flexibility, no need for cooling water, and suitability for combined cycle and cogeneration. However, there are some disadvantages, such as relatively low thermal efficiency when used as a simple cycle, not being suitable for solid fuels, and power output and efficiency being sensitive to site conditions.
Conclusion
Combustion gas turbines are a great choice for utility plants as they offer a wide range of power, a high power-to-weight ratio, and fuel flexibility. They also require no cooling water, are suitable for combined cycle and cogeneration, and have a minimum environmental impact. However, there are some disadvantages, such as relatively low thermal efficiency when used as a simple cycle, not being suitable for solid fuels, and power output and efficiency being sensitive to site conditions.
How Steam Turbines Work and Their Different Types
Steam turbines are a type of turbine used to convert thermal energy into mechanical energy. They are commonly used in power plants to generate electricity. Steam is generated in boilers, which is then used to turn the turbine shaft to generate power.
The three main types of steam turbines are condensing, back-pressure and extraction turbines. Each type has its own unique design and applications. Understanding how they work and the differences between them is essential for selecting the right turbine for the job.
Condensing Turbines
Condensing turbines are the most common type of steam turbine. In this type of turbine, steam is fed into the throttle and expands to the condensing pressure. The pressure difference between the inlet and outlet of the throttle is used to turn the turbine shaft. The steam is then condensed into liquid form and the energy is recovered.
Back-Pressure Turbines
Back-pressure turbines are designed to operate with an exhaust pressure that is equal to or greater than atmospheric pressure. This allows the turbine to generate power to meet the process steam requirements. The pressure difference between the inlet and outlet of the throttle is used to turn the turbine shaft.
Extraction Turbines
Extraction turbines are a type of steam turbine that extracts steam at one or more intermediate stages. This is done to meet the process load or to heat boiler feed water. This type of turbine can be used in either condensing or back-pressure turbines. The pressure difference between the inlet and outlet of the throttle is used to turn the turbine shaft.
Operating Conditions
When selecting a steam turbine, it is important to consider the operating conditions. These include the ambient pressure, temperature, relative humidity, and inlet and outlet pressure losses. For example, a condensing turbine typically requires an inlet pressure loss of 100 mm H2O and an outlet pressure loss of 200 mm H2O.
Conclusion
Steam turbines are an important source of power for many industries. There are three main types of steam turbines: condensing, back-pressure and extraction turbines. Understanding the differences between them is essential for selecting the right turbine for the job. Additionally, it is important to consider the operating conditions, such as the ambient pressure, temperature, relative humidity and inlet and outlet pressure losses.