Acoustically enhanced combustion of micronized coal water slurry fuel. Final report.

摘要

A multi-faceted investigation has been carried out to demonstrate analytically and experimentally, that a high intensity acoustic field can be substantially enhance the convective transfer processes occurring during MCWSF (micronized coal water slurry fuel) combustion. The initial stage of the investigation dealt with elucidating the transient as well as time-averaged efforts of high intensity acoustic fields on the heat and mass transfer between a single spherical particle and its environment. A two-dimensional unsteady computer code was developed, which employs the unsteady conservation of mass, momentum, and energy equations for laminar flow in spherical coordinates. One objective of the present project was the modeling of MCWSF combustion in a laboratory scale combustor with and without the application of a sonic field. The influence of various operating parameters (sound frequency and level, etc.) on sonic enhancement could thus be studied. The combustion of pulverized coal (PC) was also modeled for the sake of comparison. The first of the two coal combustion experiments was performed using a flat flame methane-air burner. Micronized coal was injected in the same direction as, and burned together with the methane. The final investigation was carried out in a 300,000 Btu/h sonic combustor. For the runs conducted, SPLs of 156 dB and 145 dB, respectively, were measured below the fuel injection point and before the exit to the combustor. Frequency was held at 1400 Hz. Finally, an attempt was made to model the runs performed in the down-fired unit, using the PCGC-2 code. 61 refs., 60 figs., 8 tabs.