Coal consists mostly of carbon. Carbon melts at 3500°c and boils at 4827°c. It would be very unrealistic if "coal gas" burned at only 400°c if it is only in that state at nearly 5000°c. Not to mention the fact that the other compounds found in coal would've vapourised before it even melts, making gaseous coal impossible.
That's regardless of the fact that the way you've suggested this is too brief and lacks content such as "uses"
@therocketeer(View Post) Yes, but that's because 80% of them are bad suggestions that are completely useless or repeated suggestions (like moving solids). This one doesn't really have much of a use, and isn't even realistic. Some suggestions are thought out well though, they are more likely to get in. If they are too long though, I don't really read them. Minor details should be at the end.