Alkali enhanced biomass gasification with in situ S capture and novel syngas cleaning. Part 1 : Gasifier performance

• Previous research shows that alkali addition in entrained flow biomass gasification can increase char conversion and decrease tar and soot formation through catalysis. This paper investigates two other potential benefits of alkali addition: increased slag flowability and in situ sulfur capture. Thermodynamic equilibrium calculations show that addition of 2–8% alkali catalyst to biomass completely changes the chemical domain of the gasifier slag phase to an alkali carbonate melt with low viscosity. This can increase feedstock flexibility and improve the operability of an entrained flow biomass gasification process. The alkali carbonate melt also leads to up to 90% sulfur capture through the formation of alkali sulfides. The resulting reduced syngas sulfur content can potentially simplify gas cleaning required for catalytic biofuel production. Alkali catalyst recovery and recycling is a precondition for the economic feasibility of the proposed process and is effected through a wet quench. It is shown that the addition of Zn for sulfur precipitation in the alkali recovery loop enables the separation of S, Ca and Mg from the recycle. For high Si and Cl biomass feedstocks, an alternative separation technology for these elements may be required to avoid build-up.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Naturresursteknik -- Energisystem (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Environmental Engineering -- Energy Systems (hsv//eng)

TEKNIK OCH TEKNOLOGIER  -- Maskinteknik -- Energiteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Mechanical Engineering -- Energy Engineering (hsv//eng)

Nyckelord

Alkali

Biomass gasification

Catalysis

Entrained flow

Slag

Biomass

Catalysts

Feedstocks

Precipitation (chemical)

Recycling

Slags

Sulfur

Sulfur compounds

Synthesis gas

Biofuel production

Economic feasibilities

Separation technologies

Sulfur precipitation

Thermodynamic equilibrium calculation

Gasification

alkalinity

biofuel

carbonate

catalyst

chemical alteration

entrainment

feasibility study

gas

performance assessment

thermodynamics

Energiteknik

Publikations- och innehållstyp

ref (ämneskategori)

art (ämneskategori)