Comparison of Characteristics of Various Fixed-bed Biomass Gasifiers

Updraft Gasifier

Principle: Reactions proceed from top to bottom, and producer gas exits from the upper section.

Features: Simple structure and low cost; however, high tar content and low thermal efficiency.

Downdraft Gasifier

Principle: Reactions proceed from top to bottom, and producer gas exits from the bottom.

Features: Low tar content and high thermal efficiency, yet strict feedstock requirements and low single-unit capacity.

Two-stage Gasifier

Principle: Three-layer furnace body with precise temperature control by stages for more thorough reactions.

Features: Wide adaptability to raw materials, high gas strength, high calorific value, zero tar wastewater, and suitability for long-distance transportation of gas.

All the above gasifier types have respective advantages and disadvantages. The selection shall be determined based on comprehensive analysis of actual project working conditions.