I am arriving in Thailand (BKK) on the 23rd at 8.00 am by Air India and leaving at 17.00 hrs on China Eastern to Guangzhou. Do I need a visa to collect my checked in baggage? I don't intend to go outside of the airport but both tickets have been booked separately.
Yes, you need a visa for this, because you will need to leave the international area, collect your bags, and check them in for your next flight. This is because you have purchased separate tickets from airlines in different alliances.
Fortunately, Indian citizens can apply for a visa on arrival at BKK.
Nationals of Bhutan, India, Romania and Ukraine with a normal passport traveling as tourists can obtain a visa on arrival at Bangkok (BKK and DMK), Chiang Mai (CNX), Chiang Rai (CEI), Hat Yai (HDY), Krabi (KBV), Phuket (HKT), Samui Int'l (USM), Sukhothai Int'l (THS), Surat Thani (URT) and Utapao (UTP) for a maximum stay of 15 days. They must have a confirmed return/onward ticket with a departure within 15 days from arrival date, 1 recent passport photo and at least THB 10,000.- per person (or THB 20,000.- per family). Their passport must contain at least 1 unused visa page.
Note that you must show you have 10000 baht (~ 22483 INR), but the cost of the visa on arrival is 2000 baht (~ 4497 INR). It must be paid in cash and in baht, so you will probably need to use an ATM on arrival. To save a few minutes filling out paperwork at immigration, you can apply online for the visa on arrival and bring the printout with you.