I've never done this so by no means am I even close to informed on the process, but those wood chunks look very large compared to most lump coal I've seen. Maybe try chunking them up a little to make them smaller? I dunno just thinking out loud here. I'd love to make my own coal as well, but I got window-peeping neighbors with nothing better to do than call the city on us any chance they get. The farkers, karma will sort them out in time!!!
Good luck man keep us posted.
UDS, Akorn, Weber Red Head Kettle, Drum Grill, Gasser w/cobwebs all over it. I'm JD.