If you use Phratch, by default, you cannot load Scratch projects.
Now, if you want to load a Scratch or BYOB project in Phratch, it is possible. You just have to load the add-on. In the Add-on menu, select the ScratchLoader entry, and it will load the necessary to load Scratch. It means that you need an Internet connection !
Then, a new menu entry is available to open a Scratch project, as in the following picture.
That’s all ! You can import your Scratch project in Phratch.
Pay attention: if you modify and save your project, it will be saved in the Phratch format, not in the Scratch format.