There is no direct train route, Mr Beh. You should take airport bus from Tianjin Airport to Tianjing Railway Station first, then catch bullet train there to Beijing SOuth Railway Station. Train ticket fee: 58/69RMB for half a hour. The new Exhibition Center is not far from Capital International Airport. So, you can consider to get to Beijing by air directly from your country. Or you should take Subway Line 4 and Line 2 to Dongzhimen, then change to Bus 915 to Maliandian.