Particle behavior and char burnout mechanisms under pressurized combustion conditions
Combined cycle systems with coal-fired gas turbines promise highest cycle efficiencies for this fuel. Pressurized pulverized coal combustion, in particular, yields high cycle efficiencies due to the high flue gas temperatures possible. The main problem, however, is to ensure a flue gas clean enough to meet the high gas turbine standards with a dirty fuel like coal. On the one hand, a profound knowledge of the basic chemical and physical processes during fuel conversion under elevated pressures is required whereas on the other hand suitable hot gas cleaning systems need to be developed. The objective of this work was to provide experimental data to enable a detailed description of pressurized coal combustion processes. A series of experiments were performed with two German hvb coals, Ensdorf and Goettelborn, and one German brown coal, Garzweiler, using a semi-technical scale pressurized entrained flow reactor. The parameters varied in the experiments were pressure, gas temperature and bulk gas oxygen concentration. A two-color pyrometer was used for in-situ determination of particle surface temperatures and particle sizes. Flue gas composition was measured and solid residue samples taken and subsequently analyzed. The char burnout reaction rates were determinated varying the parameters pressure, gas temperature and initial oxygen concentration. Variation of residence time was achieved by taking the samples at different points along the reaction zone. The most influential parameters on char burnout reaction rates were found to be oxygen partial pressure and fuel volatile content. With increasing pressure the burn-out reactions are accelerated and are mostly controlled by product desorption and pore diffusion being the limiting processes. The char burnout process is enhanced by a higher fuel volatile content.
- Research Organization:
- Univ. Stuttgart (DE)
- Sponsoring Organization:
- German Federal Department for Education, Science, Research and Technology
- OSTI ID:
- 20013455
- Resource Relation:
- Conference: 24th International Technical Conference on Coal Utilization and Fuel Systems, Clearwater, FL (US), 03/08/1999--03/11/1999; Other Information: PBD: [1999]; Related Information: In: The proceedings of the 24th international technical conference on coal utilization and fuel systems, by Sakkestad, B.A. [ed.], 1091 pages.
- Country of Publication:
- United States
- Language:
- English
Similar Records
Improving Flexibility and Performance of Staged Pressurized Oxy-Combustion
Performance and flexibility improvements of Staged Pressurized Oxy-Combustion