Black liquor gasification is an emerging commercial technology
founded on decades of research and development. Its goal is to
produce a combustible mixture of raw gases as well as separate
out the inorganic pulping chemicals for recycling for the
pulping process. The processes can take place at low, 600
degrees Celsius, or high temperatures around 1000 degrees
Celsius. The predominant form of biomass energy available at
pulp mills today is black liquor, the ligninrich byproduct of
fiber extraction from wood. Black liquor contains about half the
energy of the wood input to a kraft pulp mill, along with all of
the spent pulping chemicals (Na2 and NAOH) used in the kraft
process, the predominant process for pulp production. Pulp mills
have used black liquor as an energy source since the 1930s. At
pulp mills today, black liquor is burned in so-called Tomlinson
recovery boilers to generate steam and recover pulping chemicals
for re-use. The steam is expanded through a turbine to make
electricity that meets a porti