Distinctive Effects of CaO Additive on Atmospheric Gasification of Biomass at Different Temperatures

Abstract

Calcium oxide has long been recognized as an effective in-bed catalyst for reforming or cracking tars generated in thermally decomposing hydrocarbon fuels such as biomass. Under pressures as high as 20 atm, the oxide was also widely tested as a good CO 2 acceptor to capture CO 2 on-site to produce high-caloric pipeline gas from gasifying coal and coal-coke. By using CaO as an additive of the fuel and bed material, the research detailed in this research note demonstrated that CaO could also be a substantially good CO 2 acceptor for the atmospheric gasification of biomass, provided the reaction temperature is appropriately low, such as not much over 973 K. At temperatures >1073 K, the additive exhibited basically the catalytic effect only, which led the H 2 content of the product gas to increase and the tar release with the gas to decrease.

Air–steam gasification of biomass in fluidized bed with CO2 absorption: A kinetic model for performance prediction

“…It may be noted that the type of gasifier, bed materials and biomass used shall affect the concentration of H 2 . The model results agree well with the experimental results from Mahishi and Goswami [20] and Xu et al (2005) [23] as shown in the table.…”

“…LHV (MJ/Nm 3 ) of syn gas produced via air-steam gasification can be augmented (from 5.58 to 6.12 for ER = 0.25, SBR = 1) with increase in CaO content (SOBR from 0.75 to 1.5) in the system. The reaction kinetic model is compared with experimental studies of Mahishi and Goswami [20] and Xu et al (2005) [23] and good agreement is observed. As an alternative to fossil fuel expended steam gasification, pure oxygen (or oxygen enriched air) gasification is suggested by the study, since comparable richness in H 2 in producer gas can be achieved by both.…”

“…The corresponding figures for steam gasification of saw dust [21] and Salix viminalis [22] were 45% (CaO-biomass ratio = 0.5) and 62% (CaO-biomass ratio = 4.0-4.7), respectively. Major reasons attributed to the product gas enrichment with H 2 in the presence of CaO are catalytic reforming of tars and hydrocarbons, and absorption of CO 2 from gas mixture [23].…”

Experimental study on air/steam gasification of leather scraps using U-type catalytic gasification for producing hydrogen-enriched syngas

“…Thereby the energy conversion efficiency was promoted by 14.2% compared with that without catalyst. Previous studies showed that the main components of calcined dolomite were CaO and MgO [35], in the surface of which many active sites with polarity could reduce the activation energy of tar cracking and reforming reactions by destroying the CeC and CeH bonds of tar components, thereby enhanced the transformation of tar into gases [37]. Fig.…”

Influence of CaO additives on wheat-straw pyrolysis as determined by TG-FTIR analysis

“…Detailed descriptions of the approach can be found in the literature [4,5]. Extensive research on biomass gasification with in situ CO 2 capture has been conducted using batch-type reactor [6][7][8], moving bed reactor [9] and fluidized bed reactor [10] under either atmospheric [6,9,10] or pressurized [7,8] …”