Fluidised bed technology

 New incineration plants use circulating fluidised bed (CFB) technology to recover energy from its waste. CFB technology is proven to be better suited for high moisture content waste such as sludges, sewerage waste, agricultural waste etc. The waste has to be pre-dried. A fluidized bed is a bed of solid particles, through which gas is flowing in order to liquidize it. The principle behind the operation of the beds is that the particles in a vessel offer resistance to the flow of gas inserted in the vessel basin. Waste is mixed with hot circulating sand at lower temperatures compared with conventional incineration. The lower temperatures used, together with the more uniform distribution of temperatures – which eliminates hot spots and high oxygen zones, results in reduced thermal NOx production. The low combustion temperatures promote the formation of the greenhouse gas Nitrous Oxide (N2O). It is also possible to reduce the production of Nitrous Oxide. Emissions decrease with increasing bed temperature, and increase to a certain degree with increasing oxygen concentration.