visa free transit for only one of these stop overs applicable?

Hello,

I have purchased following two flight tickets.

first flight ticket:
02.01.2020
SYDNEY 11:20
QUINGDAO 19:50
+17h stop over
QUINGDAO 13:15 (on 03.01. 2020)
HARBIN 15:10

second flight ticket:
04.01.2020
HARBIN 22:20
BEIJING 00:45 (on 05.01.2020)
+18h stop over
BEIJING 18:55
BANGKOK 00:05 (on 06.01.2020)

Do I understand correctly, that I could apply for a 72 hour visa free transit for the 31 hours in Harbin, but I would then have to stay at the airport in Quingdao and Beijing?
Is that even possible to stay at the airports over night?
Thank you for your help!!