Working principle: Coal is added from the top and enters the retort section of the two-stage gas generator (i.e. the upper section). It is heated by the heat of the gas in the lower section for low-temperature retort. The low-temperature carbonized coal gas and tar are produced, and then mixed with the partial gasification section gas rising from the lower section to form the upper section gas. After low-temperature carbonization, the coal generates semi-coke, which descends to the gasification section and undergoes oxidation and reduction reactions with the blown gasification agent (mixed with air and steam) to produce lower-section gas. Part of this gas enters the carbonization section and directly heats the coal. The other part preheats the coal in the carbonization section through the partition wall composed of vertical channels. The heat is also brought to the coal in the carbonization section through pipelines and then discharged. This is the lower-section gas.

Process flow: Qualified coal for gasification is transported toTwo-stage gas generatorThe coal bunker is then added into the two-stage gas generator through an automatic stoker. The coal is heated by the gas from the gasification section and is carbonized. The semi-coke after carbonization moves down to the gasification section and reacts with the gasification agent to generate gas (the gasification agent is composed of air and steam).

The gas generated in the gasification section is divided into two parts: one part is discharged from the gas outlet of the lower section, and the other part is mixed with the retort gas and discharged from the gas outlet of the upper section. The gas from the lower section outlet enters the cyclone dust collector, wet disc valve, and ash hopper and then enters the hot gas main pipe for dust removal. The gas from the upper section outlet enters the electric tar collector to remove tar, and then enters the gas main pipe of the two-stage gas generator to mix with the lower section gas. The mixed gas is sent to various gas consumption points through hot gas pipelines.