Thermochemical conversion of biomass III

Principle of Pyrolysis

heat > gas + liquid + char

Characteristic

Moisture (110 oC)

Hemicellulose (200-260 oC)

Cellulose (240-340 oC)

Lignin (280-500 oC)

refer to TGA profile

Fast pyrolysis

Small particles: 1-3 mm

Short residence time: 0.5-2 s

Moderate temperature: 400-500 C

Rapid quenching at the end of the process

Typical yield

Oil(60-70%),

Char (13-25%),

Gas (13-25%)

Bio-oil

Characteristic

Low viscosity

Dark brown fluid with up 15 to 20 % water

Advantages

Liquid fuel

Decoupled conversion processes

Easier to transport than biomass or syngas

Disadvantages

High oxygen and water content

Difficult to store

Hydrocracking

Directly converts biomass into liquid bio oil

Catalytically converted into hydrocarbon fuel