Are these two raids or one continuous siege in 2 kings 25?

Question

2 Kings 25:1 (KJV)

1 And it came to pass in the ninth year of his reign, in the tenth month, in the tenth day of the month, that Nebuchadnezzar king of Babylon came, he, and all his host, against Jerusalem, and pitched against it: and they built forts against it round about. 2 And the city was besieged unto the eleventh year of king Zedekiah.

2 Kings 25:8 (KJV)

8 And in the fifth month, on the seventh day of the month, which is the nineteenth year of king Nebuchadnezzar king of Babylon, came Nebuzaradan, captain of the guard, a servant of the king of Babylon, unto Jerusalem: 9 And he burnt the house of the LORD, and the king's house, and all the houses of Jerusalem, and every great man's house burnt he with fire.

One raid seems to be led by king Nebuchnezzar who takes Zedekiah to Babylon & the other led by captain of the guard Nebuzaradan who takes Seraiah the chief priest & Zephaniah the second priest, who seem to have been left in the first raid.

Are these two different raids of Jerusalem or one continuous siege?

Answer 1

It is clear that this is a single protracted seige with the "ninth year of his reign" of 2 Kings 25:1 refers to Zedekiah. The immediate context is 2 Kings 24:20 (last bit of last verse of preceding chapter):

Now Zedekiah rebelled against the king of Babylon.

OP includes 2 Kgs 25:2 in the quotations in the question, which itself provides the answer:

The city was kept under siege until the eleventh year of King Zedekiah.

As the 11th year of Zedekiah equates (roughly -- close enough!) to the 19th year of Nebuchnezzar (2 Kgs 25:8).

The broad chronology of the siege is fairly outlined in the Wikipedia article on the event, although the chronology of the fall of Jerusalem to the Babylonians is complex. Even deciding between 586 and 587 cannot be settled with certainty: see, e.g., Gershon Galil, “The Babylonian Calendar and the Chronology of the Last Kings of Judah”, Biblica 72.3 (1991): 367–378.