Introduction:

Downdraft fixed bed biomass gasifier can gasify a variety of biomass materials such as wood chips, wood blocks, pellets, herbs, straw, etc.

The flow direction of the combustible gas in this furnace is the same as the feeding direction of the biomass. A high-temperature oxidation zone is set in the furnace, and the combustible gas is sucked out from the bottom of the grate.

The structure of the downdraft gasifier requires the combustible gas to pass through the high-temperature oxidation zone, which is conducive to further cracking of tar, and the tar content is very low. During the reaction process, the amount of air supplied to the gasifier increases, and the throat area or oxidation zone of the gasifier burns more violently, causing the temperature of the oxidation zone to rise sharply in a short period of time, thereby driving the temperature of the drying zone, pyrolysis zone and reduction zone to rise through mass transfer and heat transfer;

Gasification principle:

The downdraft fixed bed biomass gasification process is mainly divided into four reaction zones from top to bottom: drying zone, pyrolysis zone, reduction zone, and oxidation zone.

1.Drying zone: The free water and bound water in the biomass evaporate, and the moisture content drops from less than 20% to below 5%. The temperature in the drying zone is 30-200°C.

2.Pyrolysis zone: Biomass is cracked under oxygen-deficient conditions to produce a large amount of non-condensable combustible gases (CO, H2, CH4, etc.) and condensable tar, with a temperature range of 200-600°C.

3.Oxidation zone: Biochar burns with supplied oxygen to produce CO2, and H2 produced by partial cracking will also react with oxygen to produce water. These two oxidation reactions will generate a lot of heat. If the oxygen supply is not enough to completely convert the char into CO2, the char will also partially produce CO, and the temperature is 800-1200℃.Due to the tar moves downward with the combustible gas, it must pass through a high-temperature oxidation zone, so the tar will undergo secondary cracking.

4.Reduction zone: At 800-1000℃ and in an oxygen-deficient environment, multiple endothermic reduction reactions will occur, increasing the content of CO, H2, and CH4 in the combustible gas and improving the calorific value of the gas produced.

Applicable raw materials:

Advantages and features:

The pyrolysis gasification furnace uses insufficient air (anaerobic) to pyrolyze organic matter into combustible gas, transforming the incomplete combustion process into a gas complete combustion process, reducing the emission of solid particulate matter to below the emission standard requirements.

The gasification system is fully enclosed, the site is clean and beautiful, and harmless to operators.

Fully automatic control process, simple and convenient operation.

All feeding doors, slag discharge doors and inspection doors are soft-sealed. A sealing cover is provided on the top of the pyrolysis furnace to avoid gas leakage. The furnace body is well sealed to ensure the effect of oxygen-controlled pyrolysis.

When the pyrolysis gas spontaneously ignites, it enters the spontaneous combustion process, and the combustion-supporting device automatically stops. The entire spontaneous combustion process reaches more than 90%, greatly reducing the operating cost. It achieves the resource utilization of thermal energy, not only making the flue gas harmless, but also reducing the total amount of CO2 emissions.

Application:

Biomass gas has slightly different calorific values depending on the different biomass materials produced, with gas calorific values ranging from 1100 to 1300 kcal/m 3, and is widely used in industrial and agricultural production fields. 30-50mm wood chips or pellets (straw, wood chips, rice husk, palm shell, bagasse, etc.) and agricultural and forestry wastes are all acceptable.

Parameter:

Factory real photos: