Hundred years of fluidization for the conversion of solid fuels

Abstract

This is a summary of the development of conversion of solid fuels in fluidized bed during the hundred years that follow the first patent of Winkler in September 1922. The Winkler gasifiers and their followers are described first. Other fuel converters, such as boilers, appeared only in the 1960–70s and became of interest because of their expected environmental advantages. Initially, bubbling bed boilers were introduced, followed by circulating fluidized bed (CFB) boilers in the beginning of the 1980s. Now, CFB is the dominant technology. The entire development has not been conditioned by technological breakthroughs, but rather by the surrounding conditions: industrial demand, wars, environmental effects, availability and price of fuels. The recent development of the presently rather mature technology depends very much on the necessity to limit greenhouse gas accumulation in the atmosphere. Although fluidized bed technology offers solutions to reduce CO 2 emissions, so far, no decisive line of application has been established for CO 2 reduction, except for the use of biomass and waste. Number of publications per year dealing with Fluidization, FBC or CFBB (from Scopus). • Fluidization was proposed in a patent for gasification of coal 100 years ago. • It took about 50 years after the patent before it was introduced for combustion. • Circulating fluidized bed proved the most suitable device for combustion of coal. • Non-circulating beds are frequently used for combustion of biomass.