Use of circulating fluidized bed technology for power generation
Combustion within a circulating atmospheric fluidized bed (CFB) has proved its efficiency for many years and distinguishes itself by both flexibility with respect to feedstock and a high level of environmental acceptability. Thanks to the additional feed of lime stone, sulphur dioxide produced during the combustion process is absorbed to a degree of 90 % yet in the combustion chamber. Gypsum produced in this process is subject to disposal together with the ash. The formation of thermal nitrogen oxides is largely excluded due to the moderate combustion temperature and a staged combustion air feeding mode. CFB allows for a high degree of material and thermal transformation processes at a steady and constant combustion temperature of app. 850 °C.
During recent years Envirotherm GmbH, apart from performing the design of coal-fired CFB power stations, has rendered specific support to power station operating companies, particularly, by conducting research studies concerning the extension of fuel feedstock ranges by envisaging an additional feed of fuel substitutes, biomass and sewage sludge. In this course, particular restructuring measures were proposed which, afterwards, were respectively implemented by operating companies.
In this context, the following activities need to be mentioned:
- Change of design of an existing pressurized fluidized bed in order to eliminate process bottlenecks which permitted a significant improvement of plant availability and full-load features.
- Adaption of control systems to modern control concepts and revamping of individual items of equipment.
- Extensive research studies concerning an additional feed of up to 40 % of biomass at a large CFB power plant (100 MWel).
In addition to CFB technology Envirotherm also provides the classic stationary fluidized bed technology.