I have a number of AutoCAD 3D Solid files which I want to convert to CADWORX Equipment without having to remodel it. Is this possible?

Depends what you mean by "convert".

You can have dumb solids in an equipment DWG model; we do this frequently for complex equipment. The intelligent bit with the CWX Equipment data is just a box and maybe some of the nozzles for ISOGEN purposes.

The easiest I think would be use your 3d solids as is, then add Generic Nozzles as needed.