A mechanistic investigation of ash deposition in pulverized-coal and biomass combustion.

摘要

This investigation details the effects of fuel constituents on ash deposition through systematic experimental and theoretical analyses of fundamental particle experiments and a suite of fuels with widely varying inorganic contents and compositions. The experiments were carried out in the Multifuel Flow Reactor (MFR) at Brigham Young University. Fuels included several biomass fuels (straw, sawdust and mixtures of straw-sawdust with other additives such as Al(OH) 3, CaCO3, etc.) and four commercially-used coals (Illinois;In deposition investigation, the most significant deposition mechanisms in a general ash deposition model - inertial impaction, condensation and eddy impaction - were selected. In this PhD work, these three mechanisms are analyzed using simulation techniques such as Fluent and programming languages such as C++. The experimental data was collected for deposition rate measurements to provide a data set for the model validations except for eddy impaction. In this model analyses, the impaction efficiency model predictions from this work indicated lower impaction efficiencies than the traditional potential flow model presented by others (Israel 1983). The experimental data by others (Lokare 2003) and the data collected in this work support these predictions and present a new impaction efficiency correlation as a function of Stokes number. Similarly, the capture and condensation models perform well and are supported by the respective experimental data. The comprehensive ash deposition model predicts ash deposition rates within 10% of experimental data and is able to distinguish the role of various additives in recipe fuels combustion. As an additional results, NOx behavior of Illinois