Question Statement:
Which of the following statements regarding the thermo-chemical gasification of agricultural crop residues in downdraft biomass gasifiers is/are CORRECT?
Options:
- (A) In a downdraft gasifier, biomass and air move downwards together, forcing tars and volatile gases to pass through a high-temperature glowing char oxidation throat ($900\text{--}1100^\circ\text{C}$)
- (B) The thermal cracking of tar in the throat results in clean producer gas with low tar content, making it suitable for internal combustion engines
- (C) The combustible constituents of cleaned producer gas are predominantly Carbon Monoxide ($\text{CO}$), Hydrogen ($\text{H}_2$), and small amounts of Methane ($\text{CH}_4$)
- (D) The Lower Heating Value (LHV) of standard producer gas typically ranges between $28$ and $35\text{ MJ/Nm}^3$