BIOMASS CARBONIZATION PLANT

The biomass carbonization process can be divided into two parts: biomass material carbonization and secondary utilization of exhaust gas.

1. Biomass Material Carbonization

Biomass material carbonization mainly takes out in a carbonization rotary kiln. In the kiln, the biomass material is gradually heated, and then undergoes a series of physical changes (dehydration and degassing) and chemical changes (polycondensation and pyrolysis). Finally, the carbonized material with a primary-pore structure is formed.

The appearance of the carbonized material should meet certain specifications and shape requirements, the internal structure must be the primary-pore structure, and at the same time, it should have high mechanical strength. The carbonization process can be divided into the following stages:

Drying Stage (<150℃):

At this stage, the external moisture and internal moisture of biomass raw materials evaporate by the heat supplied from the kiln, and the shape of the raw materials does not change at this time.

Pyrolysis Stage (150-300℃):

Raw material begins to decompose and releases gaseous products (such as CO, CO2, H2S, etc.), in addition to this, the chemical composition of the raw material begins to change. Different materials start pyrolysis at different temperatures.

Carbonization Stage (300-650℃):

Through polycondensation and thermal decomposition reactions, a large amount of volatiles is precipitated from the raw materials, such as tar, methanol, and ethylene. The material gradually softens and melts to form a colloid with three phases of gas, liquid, and solid coexisting. After that, it is transformed into semi-coke, needle semi-coke, or block semi-coke through the processes of flow, polycondensation, and solidification.

Cooling Stage (<50℃):

After the carbon is produced, it is rotated and discharged through the cooling tube on the rotary kiln, and then enters the water cooler, where it is water-cooled for about 3 minutes in an oxygen-free state. After that, it gets into the finished product silo through a closed air conveying device.

2. Secondary Utilization Of Exhaust Gas

The exhaust gas produced in the biomass carbonization process is mainly composed of two parts: the high-temperature gas produced by fuel combustion and the volatile components produced by material thermal decomposition. These gases contain small amounts of harmful substances, so they need to be treated before being released into the atmosphere.

AGICO carbonization plant mainly adopts combustion methods to treat exhaust gas. After the exhaust gas is discharged from the rotary kiln, it is sent into an incinerator to be fully burned at 800-950 ℃, so that the combustible gas and harmful substances are all transferred into CO2. The heat generated by combustion can be recovered by the waste heat boiler to generate steam.