The burner tube is the thing that's connected to the valve (the thing that says "UNITROL" on it).There should be a sleeve on it with slots that control the amount of air that the flame gets. Too much air and you get an orange flame and lots of soot. It looks like someone tried to improvise by clamping that piece of metal around the tube with that nut and bolt. That doesn't look like a factory arrangement. In the second pic you can see the gap into the tube. I'd try to close it off as much as you can and see if you get a decent flame. You should have very little orange in the flame and if you do it would be way out at the end.
EDIT: This is obviously a different model, but it shows how it's supposed to work:
https://www.youtube.com/watch?v=nSjDklZh4ws
