Gas fluidised beds are often used for generating power from materials such as waste and biomass. They consist of a bed of particles through which hot gas is passed. When the gas flow is high enough to support the weight of the particles, the bed behaves in a fluid-like manner and is agitated by bubbles that form at the bottom and grow as they move up the bed. When the combustible material is introduced, the fluid-like nature and agitation of the bed allows it to be well mixed and the particle bed maintains the combustion temperature. This is a difficult system to control as it is non-uniform and unsteady and it is difficult to select and measure a suitable control variable as the bed is opaque and any sort of probe is intrusive so that its presence affects the measurement. A measurement that avoids these difficulties is that of pressure measured at the walls of the bed; however, the resulting signal is complex and difficult to interpret and then control. This has been tackled using complex control techniques; however, it can be shown that the pressure signal in a bed is generated by the pattern of bubbles. It is straightforward to simulate this pattern of bubbles and identify features of the pressure signal with what is happening inside the bed. This greatly simplifies the control algorithm necessary to control the performance of the bed, and this can be done rigorously and easily from a single pressure signal.
|Translated title of the contribution||The control of gas-fluidised beds through pressure management|
|Title of host publication||Power plant applications of advanced control techniques|
|Publisher||ProcessEng Engineering GmbH|
|Pages||181 - 208|
|Number of pages||27|
|Publication status||Published - 2010|