Ash Melting Behavior during Co-gasification of Biomass and Polyethylene

Abstract

In the present study, cogasification of straw and polyethylene was investigated in a fixed-bed gasification system. The fusion characteristics of ash during cogasification of two different kind of straw and polyethylene were investigated by AFT (Ash Fusion Test), XRD (X-ray diffraction), XRF (X-ray fluorescence), and SEM-EDX (scanning electron microscopy and energy dispersive X-ray). The results showed that the addition of polyethylene had little influence on the mineral species in the gasified ash and only affected the deformation temperature (DT) of gasified ash. The degree of disintegration of gasified ash was positively correlated to the amount of polyethylene, which was beneficial for the gasification process. The changes in relative contents of acidic oxides (SiO 2 +P 2 O 5 +Al 2 O 3 +SO 3 ) and basic oxides (Na 2 O+K 2 O+CaO+MgO+Fe 2 O 3 ) showed a consistent trend in influencing DT of the gasified ashes of two kinds of mixtures while showed different trends in influencing the softening temperatures (ST). PE addition reduces the amount of KCl formed in gasification of RS.

Properties of Animal-Origin Ash—A Valuable Material for Circular Economy

“…Chlorine is a key compound in ash fusibility since its presence leads to the forming of inorganic mixtures with Si and reducing their fluid temperatures to about 750 • C. The molten mixtures of alkali chlorides can merge, form larger droplets and thus initiate the formation of slag. Moreover, alkali vapors that contain chlorine are prone to condensation more than non-chlorinated volatile alkalis [58]. The free-range cow manure and chicken litter examined in this study contain chlorine at a relatively low level, comparable to plantorigin biomass.…”

Carbonization of biomass: Effect of additives on alkali metals residue, SO 2 and NO emission of chars during combustion

“…Little work has been done on ash fusibility of torrefied or carbonized biomass, especially potassiumrich crops straw and stalk. Investigation of ash fusibility and transformation of alkali metals of biomass in co-gasification, co-combustion process [34,35,36,37,38] provides significant hints for improving the ash fusibility, mainly involving the conversion of alkali metals to high melting point compounds: KAlSi 2 O 6 (1500 • C), CaKPO 4 (1560 • C), Ca 2 Al 2 SiO 7 (1593 • C), K 2 Ca(SiO 4 ) 2 (1600 • C), Na 2 Al 2 Si 2 O 8 (1250 • C), CaK 2 P 2 O 7 (1143 • C), etc.…”

Modification of Ash Fusion Behavior of Lignite by the Addition of Different Biomasses

“…Thus, gasification is considered as one of the most viable technologies for chemical production from low-rank coals. Pilot tests on co-gasification of lignite and biomass in a pressurized ash agglomerate fluidized bed (elaborated in detail in a previous paper) were performed at the Gasification Center at the Institute of Coal Chemistry (ICC), Chinese Academy of Sciences (CAS), on the basis of previous experimental results. , However, slag sometimes forms during the co-gasification process of lignite and biomass because of the high concentration of alkali metals (K and Na) in biomass . Slagging not only reduces gasification efficiency but also increases the probability of shutdown of the gasification system and reduces the lifetime of the gasifier.…”

“…24,25 However, slag sometimes forms during the cogasification process of lignite and biomass because of the high concentration of alkali metals (K and Na) in biomass. 26 Slagging not only reduces gasification efficiency but also increases the probability of shutdown of the gasification system and reduces the lifetime of the gasifier.…”