Can economy passangers from international to international flights access showers in Baiyun Airport?

Certainly! You can have a rest and take a shower at the Hourly Lounge. It is located beside the metro station, on B1, main building of the terminal. It costs CNY 40 to 50 per hour between 8:00 to 22:00; CNY 240 to 300 for a whole night between 22:00 to 8:00. Have a try! :)