Researchers examine the combined effects of two combustion technologies on emissions from coal-fired boilers

Coal-fired power plants have been around for a long time to meet the world’s demands for power generation. It goes without saying that there are environmental and human health concerns that need to be addressed on this front. While there are ongoing efforts to transition to renewable energy resources, coal-fired power plants may not become obsolete just yet.

In this context, it is pertinent to explore how the efficiency of these coal-fired boilers can be improved and mitigate their harmful effects on the environment, namely greenhouse gas emissions, acid rain and photochemical smog generation and the Human health.

To this end, various combustion methods have been proposed, such as air-staged and eddy flow. However, the effectiveness of these technologies in mitigating pollutant emissions and maximizing combustion performance remains unclear. Now, in a recent study in the journal Energy An international team of researchers led by Prof. Gyungmin Choi from Pusan ​​National University, Korea, analyzed the effectiveness of combining eddy flow and air stage in improving combustion performance and reducing pollution.

“The exhaust pipe vortex (ETV) structure that accompanies the eddy flow improves flame stability and combustion performance, but has the disadvantage of generating a large amount of NO_X emissions In contrast, air-stage technology creates a fuel-rich environment in the primary combustion zone, which has a positive effect on NO_X but negatively affects combustion performance,” explains Professor Choi. “Therefore, if these two technologies are properly combined and applied in real life, a synergistic effect can be expected that reduces the emission of air pollutants and improves combustion efficiency.

Consequently, the team used simulations and experiments to study the combined effects of different eddy configurations and air stages within a 16 kW generator._he Retrofitted pulverized coal boiler. The coal boiler was made up of three sections: the eddy burner, the boiler, and the exhaust pipe.

For staged combustion, staged air was divided into two sides and tangentially injected into the boiler. Liquefied petroleum gas (LPG) was used for preheating and flame stabilization. The air flows by stages and LPG were regulated and, for each configuration, the temperature was measured by thermocouples. In addition, the amount of species in the gas phase was measured using a multigas analyzer.

Air staging with two eddy configurations, namely co-eddy and counter-eddy flames, was evaluated to understand which of them is more beneficial in terms of pollutant emission reduction. In the case of the co-turbulent burner, where the air and fuel circulated in the same direction, the carbon particles were evenly distributed due to the formation of the internal circulation zone and the ETV, two vital characteristics to optimize the design of the burner. charcoal burners. boilers.

In addition, the team observed a uniform depletion zone for the co-turbulence setup, which ensured complete combustion of the fuel, reducing emissions of gas species. It also facilitated further conversion of chemical energy into thermal energy, increasing the efficiency of combustion. In contrast, countereddy burners showed uneven distribution of coal particles, uneven depletion, and increased NO_X emissions, suggesting that a co-turbulence configuration was the best option.

In addition, the team demonstrated that the aerial scenery technology reduced environmental costs from $0.003 to $0.015 per day.

Overall, the insights from this study could prove extremely valuable in solving the environmental problems and health hazards associated with coal-fired power plants. “We have identified and studied the structure and flame of ETV for the first time, and we will continue to research and strive to use it in combustion-based industry,” concludes Professor Choi.

Provided by Pusan ​​National University