PPJ projects that come from one of the older versions of Adobe Premiere Pro, may be potentially exported to several multimedia formats (including AVI) that were or supported in that particular version of the program.
It is not clear whenever the latest version of Adobe Premiere Pro still support .ppj file type or you will have to use some of the older version of the program to perform ppj to avi conversion. At any rate, it is unlikely any 3rd party software would be capable of working with .ppj projects.