Normally there were four pyres on the mizbeach, but on Yom Kippur there were five according to Reb Mayer. Reb Yossi says normally there were three and on Yom Kippur there were four. Reb Yehuda says there were two and on Yom Kippur there were three.

Yuma 5:1

They would then bring him a ladle and a shovel. He took two cupped handfuls of kitores and he put it in the ladle. He took the shovel in his right hand and the ladle in his left. He walked through the kodesh until the two partitions (which were separated by a cubit) that divided the holy and the holy of holies. Reb Yossi says there was only one partition. The outer partition was pinned up from the south side, and the inside one was pinned up from the north side. He walked in from the south side all the way across to the north. When he was in the holy of holies, he faced the south and walked alongside the curtain until he reached the aron. When he got there he put the shovel between it’s two poles, piled the kitores on the coals, and the kodesh kadashim would fill with smoke.

He went out the same way he came in and he said a small prayer. This prayer was done in the outer chamber. He did not say a long prayer so as not to frighten the Jews.