Biomass level mesurement: Stockpile profiling and measurement of wood pellets

Application:

At a power station complex in Belgium, there is a plant where the boiler powered with wood pellets alongside the coal fired stations. The existing conveyor system can transport both fuels; the coal to its designated storage or pellets into a covered warehouse.
 
The CO2-neutral fuel arrives by ship and is transported by conveyor belts to the warehouse with a storage capacity of 100,000 tons. The pellets must be stored as dry as possible to retain their maximum calorific value and avoid self-ignition by bio degradation. Conveying of the wood pellets always produces excessive dust and filling noise. The high levels of dust in the warehouse irritates the eyes and reduces visibility below the conveyor system to just a few metres. A continuous and reliable filling level measurement is essential for the constant supply of biomass fuel.

Compared with coal, wood pellets are lighter, have a lower calorific value and they degrade more quickly, so they need to be used in their optimum condition. Thus a continuous turnover of product by perfectly controlled supply logistics, storage and handling are especially important. A reliable filling level measurement technology is a key part to this.

Solution:

Two Dust ATEX approved VEGAPULS 68 radar sensors are mounted on the conveyor car. They reliably measure the filling height in the warehouse without contact and control the moving conveyor position. Heavy dust and deposits, abrasion and filling noise have no influence on the measurement. The reliability of this measurement enables the conveyor to fill the warehouse fully automatically without the need for supervision by an operator. The two radar signals have no influence on each other.
 
The radar sensors also supply the necessary information about the free storage capacities to the unloading rig at the pier as well as the available stocks for optimisation of the fuel supply to the power station control centre. This ensures there is always a supply of wood pellets to the power station.