Review

Currently, biomass carbonization processes can be broadly categorized into various carbonization technologies, including horizontal indirect biochar furnaces, open intermittent biomass carbonization kilns, and vertical continuous biochar furnaces. Through our deep exploration and meticulous work in the field of coal gasification, our company has developed the Huichuan vertical continuous biochar furnace (hereinafter referred to as the "biochar furnace").

The biomass carbonization furnace utilizes rural straw, agricultural and forestry waste, and urban discarded wood furniture as carbonization raw materials. It employs the HC new-type carbonization furnace for continuous charcoal production and gas generation. The generated biomass gas undergoes dust removal, temperature reduction, oil removal, purification, and pressurization before being used as fuel gas for production.

1. Carbonization and gas generation process:

Biomass raw materials are fed into the carbonization furnace through a feeder. The internal structural design of the furnace body divides the raw materials into multiple layers for pyrolysis treatment, as shown in the figure below. There are a total of 8 layers. The raw materials are carbonized into biochar, which is discharged from the carbonization furnace through a discharger. The gas-liquid mixture is then transported to the purification system for separation and purification.

    Drying layer: Evaporation of free and bound water in raw materials at 20-200℃.

    Pyrolysis layer: At temperatures ranging from 800 to 600 ℃, the raw material undergoes pyrolysis in an oxygen-deficient environment, producing a significant amount of combustible gases (such as CO, H2, CH4), charcoal, and biomass extract.

    Oxidation layer: 700-1100 ℃, reduction reaction.

    Reduction layer: 800-600℃

    C+H2O = CO+H2 

    CO+H2O = CO2+H2

    C+CO2 = 2CO

    C+2H2 = CH4

    CO2+H2 = 2CO+H2O    

2. Biomass gas cooling and purification process

The temperature of the gas exiting the furnace is approximately 300-350℃. The gas first enters the cyclone dust collector to remove the dust particles from it. Then, it enters the cooling tower for purification and cooling, reducing its temperature to around 70-80℃. After that, the gas passes through a droplet catcher to remove water droplets and light oil mist droplets from it. The gas is then pressurized by a Roots induced draft fan and delivered to the gas consumption point at a certain pressure.