There are still arguments on the coal combustion reactivity under conventional and oxy-coal combustion atmospheres. The selection of the experimental device in such a study is crucial. A laminar entrained flow reactor system that is capable of producing a similar combustion environment of a utility furnace in terms of the high heating rate and temperature was adopted in this study. This study investigated the characteristics of sub-bituminous coal combustion in its processes of devolatilization and char oxidation by examining the structure and length of the flame. The effects of the particle size and oxygen molar fraction in N 2 and CO 2 diluent gases were studied. The O 2 mole fraction was varied from 0 to 50%. The flame became shorter as the O 2 concentration increased. It means that reactivity in both the devolatilization and char oxidation processes increased in a higher O 2 concentration environment. It was barely seen that the volatile burning realm shrunk, O 2 diffusion accelerated, and luminosity concentrated near the burning particle as the O 2 concentration increased. The larger size coals showed thicker and longer flames, and there is a small difference in the burning time between two different sub-bituminous coals. When the O 2 /CO 2 and O 2 /N 2 environment effects are compared, the flame was shorter in the oxy-fuel condition than in the O 2 /N 2 condition.

Char oxidation experiments were performed with a sub-bituminous roto-middle coal in the Drop Tube Furnace (DTF) at atmospheric pressure condition. While temperatures varied between 900, 1100, 1400, particle ℃

No abstract

No abstract

Integrated Coal Gasification Combined Cycle (IGCC) power plants have been developed to reduce carbon dioxide emissions and to increase the efficiency of electricity generation. A devolatilization process of entrained coal gasification is predicted by CPD model which could describe the devolatilization behavior of rapidly heated coal based on the chemical structure of the coal. This paper is intended to compare the mass release behavior of char, tar and gas(CO, CO 2 , H 2 O, CH 4) for three different coals. The influence of coal structure on gas evolution is examined over the pressure range of 10~30atm.