Stoichiometric, mass, energy and exergy balance analysis of countercurrent fixed-bed gasification of post-consumer residues

Abstract Air-blown gasification studies were conducted on a countercurrent fixed-bed gasifier for municipal residue-based Refuse Derived Fuel (RDF) pellets and compared with the mass and energy performance features of gasifier with other biomass and residual fuels. The mass conversion efficiency and cold gas efficiency (CGE) of the gasifier were observed to be 83% and 73%, respectively for RDF pellets. The higher heating value and global energy content of the producer gas generated from gasification of RDF pellets was observed to be 5.58 MJ Nm −3 and 12.2 MJ kg −1 , respectively. The tar content in the gas generated from RDF pellets was observed to be about 45% less than the tar content in the gas generated from wood chips (WC). Empirical stoichiometric equations were developed to describe the gasification of different fuels. A complete thermodynamic analysis was performed to determine the magnitudes of various inefficiencies and irreversibilities involved in the process. It was evaluated for RDF pellets that 27% of the exergy or available energy input was dissipated in the system due to various irreversibilities taking place in the gasification process. The second law CGE was observed to be highest for RDF pellets i.e. 56% followed by charred soybean straw pellets and WC. Thermal energy in the form of sensible heat energy accounted for 6–7% of the total energy; the available energy accounted for 2–3% of the total energy output of the process.

[1]  Jukka Leppälahti,et al.  Updraft gasification of peat and biomass , 1989 .

[2]  L. T. Fan,et al.  Estimation of Energy (Enthalpy) and Exergy (Availability) Contents in Structurally Complicated Materials , 1982 .

[3]  Albrecht Kaupp,et al.  Small Scale Gas Producer-Engine Systems , 1984 .

[4]  Esa Kurkela,et al.  Development of simplified IGCC-processes for biofuels: Supporting gasification research at VTT , 1993 .

[5]  L. K. Mudge,et al.  Fundamentals of thermochemical biomass conversion , 1985 .

[6]  H.E.M. Stassen,et al.  Biomass gasification: field monitoring results , 1989 .

[7]  G. E. Lightner.  Production of syngas from a biomass , 1994 .

[8]  R. Reid,et al.  The Properties of Gases and Liquids , 1977 .

[9]  Jesús Arauzo,et al.  Scale-up of downdraft moving bed gasifiers (25-300 kg/h) - design, experimental aspects and results , 1994 .

[10]  Gao Xian Sheng.  Biomass gasifiers: from waste to energy production , 1989 .

[11]  J. I. Joubert,et al.  Fuels and combustion , 1978 .

[12]  L. T. Fan,et al.  Mass and energy balance analyses of a downdraft gasifier , 1989 .

[13]  G. J. Esplin,et al.  Development of sampling and analytical procedures for biomass gasifiers , 1985 .

[14]  Cift.  Annual Report 1996-'97 , 1997 .

[15]  D. Klass.  Energy from Biomass and Wastes , 1984, Bio/Technology.

[16]  Eddie G. Baker,et al.  Environmental design considerations for thermochemical biomass energy , 1986 .

[17]  D. O. Hall,et al.  Biomass : regenerable energy , 1987 .

[18]  L. T. Fan,et al.  Operating parameters influencing downdraft gasifier performance. , 1988 .