Stringent emission regulations force the gas turbine combustor community to come up with new designs. Lean Premixed combustion (LPM) is gaining popularity to meet the emission regulations. However, lean combustion process is prone to other issues like combustion instabilities and noise.
Self-excited combustion instabilities in a gas turbine play a vital role in the lifecycle of combustor, noise generation and pollutant formation. If the instabilities in the combustor dominate at natural modes, there are risks of resonance that can lead to bursting damage to the combustors. Therefore, it is necessary to understand the combustion dynamics performance of a given lean premixed combustor. Continue reading
In a past blog, I discussed gasification as a clean coal technology (CCT). Today, my discussion is about oxy-fuel combustion as another clean way of burning fuels. CFD is widely used to design oxy-fuel combustion systems that burn as cleanly as possible. One of the most important decision when simulating such systems is to choose the modeling strategy that will give accurate and reliable predictions of the combustion performance and pollutant emissions levels. In oxy-fuel combustion, the oxygen required for combustion is separated out from air prior to combustion. Fuel is burned in either an oxygen-rich (~95% oxygen) environment, as in welding and cutting of metals where higher flame temperature is required, or diluted with recycled flue-gas, as in pulverized coal-fired boilers.
Oxy-fuel combustion using pulverized coal as fuel with flue-gas recirculation is gaining popularity in electricity-generation application. This is due to the fact that flue-gas contains mainly carbon dioxide after condensing the water vapor, and it is, therefore, a good candidate for CO2-capture-and-sequestration. Since these types of power plants have lower NOx emission — nitrogen from the air stream is absent — an optimized oxy-combustion power plant has lower overall emissions. Continue reading
Coal will remain the key fuel for electricity generation in the near future, despite its major contribution to the greenhouse effect. That was the key takeaway from the 38th International Technical Conference on Clean Coal and Fuel Systems, which concluded recently in Clearwater, Florida, U.S.A. A large focus of the event was to provide information about the cleaner use of coal now and in the future.
That message was expected, given that there has been a concentrated effort by many researchers and engineers to make energy from coal as clean as possible. It was interesting to hear one of the speakers directly couple the economic growth of a country with its use of coal.
The five-day conference provided comprehensive and up-to-date information on emerging, evolving and innovative technologies, fuels and policies in the power generation industry. Information and discussions during the conference help industrialists, academicians, researchers, and technology and equipment suppliers to plan their strategies for cleaner use of coal to mitigate environmental concerns in the 21st century. Continue reading