97/02136 Dynamic simulation of advanced PFBC plant operation

Abstract

The Advanced or Second-Generation Pressurized Fluidized Bed Combustor (APFBC) concept is an efficient coal-fired combined cycle. This concept utilizes mild gasification to produce a low-Btu fuel gas and char from coal. Fuel gas generated in the carbonizer is combusted and expanded in a gas turbine (GT) following solid particulate removal. GT combustion air is directly heated through char combustion in a pressurized fluidized bed combustor (PFBC). A fluidized bed heat exchanger (FBHE) and heat recovery steam generator (HRSG) is used to remove heat from the process. Heat recovered in the FBHE and HRSG is utilized in a steam turbine cycle. The carbonizer and PFBC are large vessels containing significant volume. The freeboard volume of the carbonizer is approximately an order of magnitude greater than that of the GT. The PFBC volume is roughly six times greater than that of the carbonizer. The carbonizer, PFBC, and FBHE all have thermal inertias due to the presence of solid particles. The steam bottoming cycle contains both slow dynamics, such as those associated with evaporative steam drums, and quick dynamics, such as those present in a high pressure steam header. The dynamic response of each component affects the other components due to the highlymore » integrated nature of the APFBC combined cycle concept. A dynamic model of a commercial-size APFBC power plant was constructed in order to determine representative operating characteristics of the APFBC plant and to gain some insight into the best type of control system design. The dynamic model contains both process and control model components. This paper describes development of the model used to describe the commercial APFBC power plant. Results of exercising the model to simulate plant performance are presented.« less