Two-section gasifier, from top to bottom, consists of carbonization section and gasification section. Through the carbonization section, coal is sufficiently dried and destructively distilled under low temperature for a long time. The gas produced during the process of carbonization is called carbonization gas, namely upper gas. With high calorific value, the temperature of the gas is low and it contains low-temperature tar. After carbonization, the coal turns into carbon coal and enters gasification section where it fully reacts with gasification agent which enters the bottom of the gasifier. The so-produced gas is called gasification gas, namely lower gas. With low calorific value, the temperature of the gas is high and it contains dust.
  The gas produced by two-section gasifier has high and steady calorific value and its gasification efficiency and comprehensive heat efficiency are both higher than single-section gasifier, such as coaling automatically or manully by motorized pulleys of two-path, high ash pan water seal, high pressure gasification operating, high operating flexibility and automatic poking or hand-poking. For this type of gasifier, the labour intensity is low, while the automaticity is high.