Doing a search, I found one program that may work. You can check it out here:
VeryPDF PDF to EPUB Converter. It uses a command line to convert and ignore images. There's also Adobe Acrobat itself (or other PDF editors) that can be used to remove images, but that has to be done one file at a time. Otherwise you may be stuck doing it manually as there's no other automagic way (that I've ever personally seen) of stripping images besides just converting / saving to pure text.