Combustion Science and Technology

PAYNE, R.; L CHEN, S.; WOLSKY, A. M.; RICHTER, W. F.

doi: 10.1080/00102208908924058pmid: N/A

Abstract The combustion of coal in oxygen with recycled flue gases has been proposed as a means of recovering carbon dioxide during power generation in existing boilers. The feasibility of this process has been evaluated in a pilot scale test furnace and by the use or a boiler performance model to assess the impact on the performance of a 50MWe lignite fired boiler using oxygen plus recycled products as the oxidant. Results show that flue gas recycle is a viable means of controlling combustion and heat transfer characteristics, and that recycle conditions exist at which performance changes are minimal compared to operation on air.

LHUISSIER, N.; GOUESBET, G.; WEILL, M. E.

doi: 10.1080/00102208908924059pmid: N/A

Abstract The data obtained by Quasi-Elastic Light-Scattering Spectroscopy on twenty five alkane-oxygen sooting flames are presented. This optical method, based on the interaction between particles and their surrounding, allows the granulometric study of the soot aerosol evolution accounting for the specific aerosol regime existing in the considered flame. Diffusion Broadening and/or Photon Correlation Spectroscopy adapted to a Brownian aerosol in a flowing high temperature medium are used for the simultaneous measurements of soot diameter and number density or diameter and polydispersity. The data reduction method employed permits easy analysis including the transit time and the polydispersity aspects of the scatterers. Soot coagulation growth rates are also determined for these flames.

CHO, S. Y.; TAKAHASHI, F.; L DRYER, F.

doi: 10.1080/00102208908924060pmid: N/A

Abstract The combustion and disruption or free slurry droplets are studied theoretically to elucidate a mechanism for the overall disruptive burning process. The disruptive burning process consists of three stages; a d2-law stage, a shell formation stage, and a disruption stage. It is proposed that the agglomeration of particles near the droplet surface due to capillary forces causes the shell formation and that the pyrolysis of additives due to the temperature rise in the outer surface of the shell produces an impermeable shell immediately and eventually disruption activity. A simple mathematical model is formulated to predict the shell formation and disruption time, and the fragmented shell thickness. The model simulation results for the disruptive burning of boron/JP-IO slurry droplets show good agreements with Takahashi er al. (1988a, b)'s experimental results. The disruption time increases with increasing initial slurry droplet diameter or increasing initial boron loading. The thickness of the fragmented shell increases as the initial diameter or the initial boron loading is increased. Finally, results show that the disruption time increases significantly whereas the thickness of the fragmented shell increases slightly as the environmental oxygen concentration is increased.

GODOY, S. G.; ISMAIL, M.; LOCKWOOD, F. C.

doi: 10.1080/00102208908924061pmid: N/A

Abstract Species concentration, temperature and char burnout data are presented for a cylindrical furnace fired with a bituminous pulverized coal for a burner swirl number of 1.45. These data are compared with previously reported data for the lower swirl numbers of 0.78 and 1.03. They permit a rational physical description of the near burner field to be constructed, and highlight the importance on combustion performance of parameters like residence time and mixing which are directly related to strength of swirl.