Effects of different sodium species on PM10 formation during high-sodium coal gasification by using McKenna burner

PM10 generated from high-sodium coal combustion results in considerable ash deposition. A comparable occurrence may arise during high-sodium coal gasification. This work added NaCl and NaAc to the HCl acid-washed high-sodium coal to investigate their contributions to PM10 formation during entrained flow gasifica-tion. The PM10 from HCl acid-washed and NaAc-addition coal gasification showed a bi-modal distribution, while it exhibited a tri-modal one for the NaCl-addition coal. NaCl and NaAc increased PM10 production, but this increase is relatively minimal compared to coal combustion due to the lower Na release rate. NaCl formed more PM1 than NaAc because of variations in their transformation mechanisms. NaCl vaporized and directly formed flocculent PM with sizes less than 1 mu m by nucleation/condensation without sulfation. NaAc was mainly released as Na atoms formed spherical PM with sizes less than 0.255 mu m by hydrochlorination and nucleation/conden-sation. The simulations suggested that the faster release rate of NaCl than NaAc was the main reason for this phenomenon. Besides, simulation results also indicated that gasified refractory elements have a strong coagu-lative effect on NaCl and NaAc, which promoted particle growth and determined the location and peak of the PM1.

Automated summary

PM10 generated from high-sodium coal combustion and gasification was studied in this research by adding NaCl and NaAc to investigate their contributions. The results showed that both NaCl and NaAc increased PM10 production, with NaCl forming more PM1. NaCl vaporized and directly formed particles through nucleation/condensation, while NaAc released as Na atoms and formed spherical particles through hydrochlorination and nucleation/condensation. The faster release rate of NaCl than NaAc was found to be the main reason for the difference.