Hydrodynamic Modelling of Municipal Solid Waste Residues in a Pilot Scale Fluidized Bed Reactor

Abstract

Abstract:The present study investigates the hydrodynamics and heat transfer behavior of municipal solid waste (MSW) gasification in a pilot scale bubbling fluidized bed reactor. A multiphase 2-D numerical model following an Eulerian-Eulerian approach within the FLUENT framework was implemented. User defined functions (UDFs) were coupled to improve hydrodynamics and heat transfer phenomena, and to minimize deviations between the experimental and numerical results. A grid independence study was accomplished through comparison of the bed volume fraction profiles and by reasoning the grid accuracy and computational cost. The standard deviation concept was used to determine the mixing quality indexes. Simulated results showed that UDFs improvements increased the accuracy of the mathematical model. Smaller size ratio of the MSW-dolomite mixture revealed a more uniform mixing, and larger ratios enhanced segregation. Also, increased superficial gas velocity promoted the solid particles mixing. Heat transfer within the fluidized bed showed strong dependence on the MSW solid particles sizes, with smaller particles revealing a more effective process.

Comparative scaling analysis of two different sized pilot-scale fluidized bed reactors operating with biomass substrates

“…These routines make use of a set of polynomial equations created to enhance the fluidization process, increasing the model's accuracy and predictability by minimizing deviations between the experimental and numerical results. Such UDF improvements were already confirmed and validated in previous works [4,20]. The five gasification runs, previously described in Section 2.2, using eucalyptus wood as a fuel and atmospheric air as gasification agent were also used to evaluate the model fitting regarding the different syngas composition species.…”

“…The heat absorption and thermal conductivity between the gas and the two solid phases were defined by implementing a UDF. This already implemented and validated routine adapts the default gas and solid phases heat absorption and transfer coefficient, by applying a set of polynomial equations designed to improve the gas-solid heat interactions [4,20].…”

“…The applied routine acts over the drag coefficients values fitting the solution to our modeling needs towards a better agreement with the experimental setup. The UDF routines improvements over the fluidization process were already validated in previous papers published by the authors [4,20]. Syamlal-O'Brien drag function for a single spherical particle in a fluid goes as follows [21]: Further information regarding the model can be found in [7,8,23].…”

Modelling and experimental analysis of a small-scale olive pomace gasifier for cogeneration applications: A techno-economic assessment

“…Producer gas samples are then inserted into the chromatograph for further analysis within one hour after collection. Additional details on all remaining components are fully explained in [16,17].…”

Exergo-Ecological Assessment of Waste to Energy Plants Supported by Solar Energy

“…Gasification of MSW has been proposed as energy conversion method. It was shown that the process could be enhanced when MSW is reduced to small particle sizes [6]. However, among others possible thermal treatments for energy recovery from waste, nowadays, combustion processes-in the following simply named WtE-are the most commonly widespread and applied for different types of waste, including MSW [7].…”