Thermochemical Processes

What is the Difference Between Gasification, Pyrolysis and Liquefaction?
Although liquefaction, pyrolysis and gasification are three, similar thermochemical processes designed to convert carbonaceous feedstock at elevated temperatures into usable products, they should not be confused with one another. Of the three processes, liquefaction uses the lowest temperatures to alter a substance from a solid into a liquid state; pyrolysis is the thermal degradation or volatilization of a substance without the addition of air or oxygen at temperatures between 400° to 800° Centigrade to generate a combination of liquid and gaseous products; and gasification is a more reactive thermal process with the controlled introduction of air, oxygen, or steam at temperatures between 700° to 800° Centigrade to generate primarily gaseous products.

Pyrolysis and gasification are similar, multi-step processes, typically including: (1) feedstock preparation; (2) introduction of the feedstock into the reactor; (3) the pyrolytic decomposition (in the case of pyrolysis), or gasification reaction; and (4) separation and post-processing of the gases, oils (in the case of pyrolysis), solid char and ash.

Improvements in gasifier system efficiency, combined with the higher cost of oil and natural gas, make environmentally clean biomass energy through gasification a more competitive alternative. The process can now be made to operate economically even on a relatively small scale, making it of growing importance to the need for an increasingly decentralized energy distribution network.