Method of purification of biomass syngas under positive pressure

A method for purifying biomass syngas, comprising:

• a) aerating a pyrolysis gasifier using an oxidation fan;
• b) introducing syngas produced in the pyrolysis gasifier through a water-cooling flue to a water-cooling quench tower, where water is sprayed into the syngas for quenching slag;
• c) introducing the syngas from the water-cooling quench tower to a waste heat boiler of a water-tube type to yield a first cooled syngas and a first vapor;
• introducing the first cooled syngas to a waste heat boiler of a heat-tube type to yield a second cooled syngas, a heavy tar, and a second vapor;
• and supplying the first vapor and the second vapor to external devices;
• d) washing the second cooled syngas in a Venturi scrubber in the absence of a filler to yield a first purified syngas;
• e) introducing the first purified syngas from the Venturi scrubber to a wet electrical dust precipitator to yield a second purified syngas having a dust content <10 mg/Nm3, a tar content <10 mg/Nm3, and a temperature <45° C.;
• and
• f) transporting the second purified syngas to a wet gas tank for storage or to a downstream process for use;
• wherein an outlet pressure of the oxidation fan is controlled to provide positive pressure to the water-cooling quench tower, the waste heat boiler of the water-tube type, the waste heat boiler of the heat-tube type, the Venturi scrubber, the wet electrical dust precipitator, and the wet gas tank.