What is the name of this animated movie?

The movie is animated. Not Disney/Dreamworks/Don Bluth. Only scene I remember is in the reception (red carpet) area of the Kings palace. The boy hero is meeting the king and some black goo comes from somewhere and captures the king and maybe the Princess (?). I seem to remember that maybe the boy was an inventor or something like that. I think there may have been zepplins in the movie too. Animation-wise, it seemed an older style... late 80's, early 90's maybe? Not the super color saturated movie like Disney. The artwork seemed Japanese though the setting of the movie seemed sort-of European. Thanks.