Slagging Behavior of Straw and Corn Stover and the Fate of Potassium under Entrained-Flow Gasification Conditions

Abstract

The behavior of straw and corn stover (non-food agricultural residues potentially available for power generation) was studied in a lab-scale reactor under entrained-flow gasification conditions typical for existing integrated gasification combined cycle power systems. This experimental work was assisted by a range of ash-specific analyses and thermodynamic modeling to gain insights into both the physics and chemistry of ash formation and melting behavior. It was observed that, although the major part of the primarily siliceous native ash promptly forms a molten slag, much of the alkalis are evaporated into the syngas. These gas-borne alkalis can potentially cause aerosol formation in the gasifier, gas quench, syngas cooler, and quench systems, resulting in both operating problems (fouling) and emission issues. To minimize the alkali release from straw and corn stover, the addition of an additive (clay) has been proven to be a highly promising method without the negative effects for the melting behavior of the slag.

A review of catalysts for the gasification of biomass char, with some reference to coal

“…A study by Leiser et al examined the gasification of pulverised straw and corn stover in entrained flow with pure oxygen [65]. The trials resulted in >99% burnout after 2 s, with any potassium collected at 600 C appearing as flyash, predominantly as potassium salts (KOH, KCl and K 2 SO 4 ) in the sub-micron range.…”

Influence of biomass addition on Jincheng coal ash fusion temperatures

“…Several researchers have studied the ash fusion temperatures or slag characteristics of different rank coals [12,13] and various biomasses [14,15]. However, only a few investigations [16,17] are closely related to the coal and biomass blending ash.…”

Tensile and flammability characterizations of corn straw slagging/high-density polyethylene composites

“…5,6 During biomass combustion, the alkali metal or alkaline earth metal was volatilized in the form of gas, then condensed on fly ash particles in the form of sulfates or chlorides, which reduced the melting point of fly ash and increased the surface viscosity of fly ash, and the slagging formed on the heated surface under the action of the furnace gas flow. 7 On the utilization of slagging, many scholars have also carried out some relevant research. Etiegni et al 8 thought that there were inorganic substances in straw slag, which could expand after water contact, which may block the gap of soil and reduce the permeability of soil, but it could improve the water storage capacity of soil.…”