Not even in the ballpark. By 800F, all the water is gone and the carbon has burned or is burning…which creates heat rather than uses heat. There is probably 1/10 or less of the original mass to heat from 800Fto 1600F F. So the shitty analysis has a HUGE error in it that greatly overestimates the fuel required. A shitty estimate like that would never have gotten by this experienced engineer in a project review.