Potential of molten lead oxide for liquid chemical looping gasification (LCLG): A thermochemical analysis. (1st March 2018)

• Record Type: Journal Article
• Authors: Sarafraz, M.M.; Jafarian, M.; Arjomandi, M.; Nathan, G.J.
• Is Part Of: International journal of hydrogen energy. Volume 43:Number 9(2018)
• Page Start: 4195
• Page End: 4210
• Publication Date: 2018-03-01
• Subjects: Liquid chemical looping gasification -- Molten lead -- Nitrogen dilution -- Power block -- Syngas production; Hydrogen as fuel -- Periodicals; Hydrogène (Combustible) -- Périodiques; Hydrogen as fuel; Periodicals; 665.81
• DOI: 10.1016/j.ijhydene.2018.01.035
• Languages: English
• ISSNs: 0360-3199

Abstract

Abstract: Molten lead oxide is revealed to have favourable thermodynamic performance for gasification in a new process employing chemical looping of a molten liquid metal oxide. In this process, the feedstock is partially oxidized with molten lead oxide in the fuel reactor, while the reduced molten lead is oxidized in the air reactor. As with other chemical looping processes, this avoids direct contact between air and fuel, which prevents the undesirable dilution of the gaseous product with nitrogen. The Gibbs minimization method was employed together with thermo-chemical equilibrium analysis to assess the feasibility of the gasification process using graphite as a surrogate for more realistic, but complex carbonaceous fuels, together with steam and/or carbon dioxide as the gasifying agent. It was found that both the reduction and oxidation reactions of molten lead oxide with carbonaceous fuel are spontaneous. Likewise, the ratio of H2 :CO can be as high as 2.5, while the carbon conversion can reach 94% based on the thermochemical analysis. An energetic performance analysis was also employed for the case of a supercritical steam turbine cycle to extract work from the hot gaseous co-products. On this basis, the first law efficiency of the power cycle was estimated to be up to 33.8%, while the syngas co-product stream for applications such as Fischer-Tropsch synthesis has a chemical exergy efficiency of 41%. Highlights: A concept for the gasification of fossil fuels is thermodynamically assessed. Molten lead oxide is used as an oxygen carrier. Chemical performance of the system modelled using HSC chemistry. Energetic performance of a steam turbine power block connected to LCLG is studied.