Authorize Transit hours in Pudong Shanghai Intl Airport

Hi Iris,
follow up questions for other Option.
Can a transit spend more than 24 hours in any Chinese airport, say 48 hours? I have a confirm flight on 22 April 2012 from Hong Kong to Shanghai (arriving in Shanghai 10:30 AM). My connecting flight schedule is on 23 April (1:00 PM), it's 3.5 hours difference. This is 27.5 hours and more than 24 hours. Is this authorized in the airport. I won't go out from the immigration/port of entry. I will only stay at the departure area and wait. will this situation be possible and authorized? Please advice. Thank you. Will J