Brussels - Shanghai Pudong - Singapore - Brussels

I have booked following flights:

12/01/13 Brussels - Shanghai
15/01/13 Shanghai - Singapore
18/01/13 Singapore - Brussels

Does this mean I do not need a visa for Shanghai and can benefit from the 72-hours visa-free transit in Shanghai. How does this procedure work, can I just leave Brussels without visa and am I sure not to encounter problems in Shanghai? I can't find any information on the embassy website about this even my travel agency is not aware about this.
Thank you for your fast reply.