Asked by Canadian Citizen, will be taking a flight from Toronto-HK-BJ-Van-Toronto

I'm holding a Canadian passport, and will flying from Toronto for HK on June 26th. My return ticket will transit via Beijing on July 26th and depart on July 29 2:00am., then fly via Vancouver and back to Toronto. Will a 72 hours visa free permit applied to my situation? If do so, when I arrived to Beijing on July 26th, how and where can I get the free permit in the airport? During a 72 hour free permit period, can I go to nearby city - TienJin for sightseeing also?