A COMPARISON OF THE AHLSTROM PYROFLOW PRESSURIZED CIRCULATING FLUIDIZED BED AND COMPETING PRESSURIZED BUBBLING FLUIDIZED BED COMBUSTION TECHNOLOGIES

摘要

Much has been published regarding the two pressurized fluid bed combustion technologies now under development and demonstration. These technologies, the Pressurized Circulating Fluidized Bed (PCFB) and Pressurized Bubbling Fluidized Bed (PBFB), both show great promise for clean, efficient, and cost effective generation of electricity during the next century. The market is becoming increasingly competitive, as these technologies are developed and commercially demonstrated, leaving potential customers with many questions regarding the similarities and differences between the two processes. On the one hand, the PBFB system has now achieved significant operational successes, demonstrating the reality of pressurized fluidized bed combustion as a commercially viable power generation technology. On the other hand, the alternative Pressurized Circulating Fluidized Bed Technology, which is at an earlier stage of commercial development and demonstration, may offer significant cost and operational advantages when compared with the PBFB. Ahlstrom Pyropower, Inc. (API) has been invoved in the development of the Ahlstrom PYROFLOW PCFB technology since 1986. API operates a 10 MW{sub}th PCFB Test Facility at its Hans Ahlstrom Laboratory in Karhula, Finland. To date, more than 6000 hours of operation and testing of the PCFB with various coals have been completed using the PCFB Test Facility. A project to demonstrate the PCFB system in the 120 MWe scale, is in the engineering phase under the DOE Clean Coal III Technologies Program. That demonstration is scheduled to start operation in 1998. This will provide a market for competing options for users of Pressurized Fluidized Bed Systems in the future. This paper will present a brief description of the PCFB process, followed by a comparison of certain key aspects of the PCFB and PBFB technologies. These aspects include the effects of gas residence time and solids/gas contacting on combustion efficiency and emissions, complexity of fuel feed systems, pressure parts arrangement and erosion considerations, component sizes and plant space requirements, and plant operation and load following.