Session: 08-05-01: Energy-Related Multidisciplinary I

Paper Number: 144972

144972 - Simulation of Oxygen-Enhanced Municipal Solid Waste Combustion in a Novel Cyclonic Furnace 

Increased investment in the electrolytic separation of water for both utility-scale and distributed hydrogen; the drive for effective carbon capture; the continuing need for economical waste recycling; concerns resulting in legislation addressing solid waste landfill emissions and land usage; and the closure of numerous coal-fired thermoelectric plants; taken together, provide opportunities for new waste-to-energy system designs.

This study investigates an oxygen-enhanced combustion (OEC) employing flue gas recirculation (FGR) thermal dilution, in a scheme intended to mitigate the challenges associated with municipal solid waste (MSW) as fuel.

First, based upon literature review, a baseline fuel composition and a simplified treatment train are established. The OEC combustion of the heterogeneous solid fuel with significant moisture content and moderate energy content is next examined: variations in combustion chamber radiative flux, chamber gas specific heat and viscosity, concentration of carbon dioxide in flue gases, and thermal performance are derived from a series of simulations. A revised furnace configuration is proposed to potentially reduce the high maintenance costs associated with refractory erosion and low availability in cyclonic furnaces, thereby enhancing the possibility of retrofitting existing fossil fuel plants.

The MSW feedstock is considered to have undergone coarse shredding; magnetic, eddy, and density separation to remove (using common removal efficiencies) salable ferrous, aluminum, and glass, respectively; liquid draining; and one stage of ball milling. The maximum water content derived from preliminary calculations is 25%, and the expected mean particle diameter is 6 mm, prior to any heating.

Ash and fixed carbon particle streams are modeled using a Rosin-Rammler distribution with dehydration/devolatilization volume reduction for the fixed carbon particles. Volatiles are modeled as carbon monoxide and methane with water content; solid fuel as carbon particles, and slag/ash as calcium oxide. A cyclonic slagging furnace operating at slightly elevated pressure is used to increase residence times for the large particles while minimizing chamber volume.

Ultimate and proximate analyses from an existing study of typical landfill MSW composition in Michigan are used as the baseline fuel composition for the first simulation run. A low-grade coal fuel will be simulated, and the results will be compared to simulation and experimental data obtained from a previous study (by others), as validation. Heterogeneity and moisture content effects are to be assessed by simulation of modifications of the baseline Michigan waste with a high concentration case and a low concentration case (+20/-20 mass percent from the baseline) for significant individual constituents.

A series of multiphase 3d reacting flow Ansys Fluent simulations, using a common setup that includes radiation and soot, provides the basis for final analysis. For additional input data, the open-source process software DWSIM is used in a 17 MW nominal input Gibbs reactor simulation to determine overall wall cooling loads, FGR mass flow and compositions using fixed vessel discharge temperature (2373K), overall oxygen concentration (30%) and residual (3%), and dry FGR ratio (70%), which preliminary calculations and a literature review show to be within effective practical ranges.

Cooling requirements, radiative flux patterns, and variation in the idealized performance relative to feedstock composition are to be analyzed and the practicality of the application with respect to thermal output, residence times, and wall cooling is to be assessed. A basic economic analysis incorporating oxygen separation costs is intended. Preliminary simulations indicate reasonable performance and agreement between DWSim and Fluent.

Presenting Author: Duane Brow Lawrence Technological University

Presenting Author Biography: Founder and former President of Superior Fluid Systems, an industrial mechanical design, fabrication and installation company. BSCE, Lawrence Technological University; MBA, Wayne State University; MSME, Lawrence Technological University; current PhD ME student, Lawrence Technological University.

Authors:

Duane Brow Lawrence Technological University
Badih Jawad Lawrence Technological University
Hossam Metwally Lawrence Technological University
Vernon Fernandez Lawrence Technological University
Selin Arslan Lawrence Technological University
Liping Liu Lawrence Technological University
Nikolina Samardzic Lawrence Technological University