Typically scrap metal dealers will not take burnt wire because they do not want to be accused of encouraging their customers to poison the air. Also, when you burn wire, you lose nearly half of it unless it's #14 or thicker.
I am a member over at scrapmetalforum.com where they come up with all kinds of ideas for stripping the wire. There are actual wire stripping machines that you can get for a few hundred dollars. It's probably worth it if you scrap enough wire in a month to pay for it. Also, I've seen a technique where somoene stacked an empty oil barrel on top of another that was burning wood. The barrel on top had a hole on both sides and the person demonstrating the technique pulled the wire through both holes allowing it to heat up warm enough to soften the jacket where it could easily be pulled off by hand while wearing gloves.
