Bed material load
The term refers to a bulk granular or lumpy mixture which is in a pourable form. It determines the properties of bulk material by the particle size and the particle size distribution and bulk density, angle of repose, the humidity and the temperature.
Solids can be distinguished into two groups:
- Cohesionless, free-flowing bulk materials
- Cohesive, cohesive bulk materials
The term " spill " is defined in the DIN standards of transport and process engineering concept with the handling of bulk materials. A bed, especially the loose fill, means any goods which are free to move in a container or are not otherwise secured in position.
The bulk mechanics deals with storage and transport conditions of bulk materials such as angle of repose ( angle of repose ), discharge behavior of silos, fluidization and bulk density. After activation energy is exceeded, bulk materials can behave like a fluid, ie flow. The particles are retained substantially or change their shape in transit. The most important parameter for this is the flowability. Be treated Physical properties of the bulk material in the theory of granular matter.
Features
Species
The bulk materials include materials such as topsoil, sand, gravel, cement and raw materials such as ore, coal or salt. Further facilities include foods such as cereals, sugar, salt, coffee and flour to the group of bulk materials. Powdered materials such as pigments and fillers, granules and pellets can be assigned as well.
Storage and transport
Bulk materials are often stored in silos or bunkers due to their material properties. Depending on material property, a distinction is free-flowing and cohesive bulk materials. The former are easily unsubscribe with, for example, a rotary valve or using a slider. In difficult (complex) bulk materials, for example, in cohesive, hygroscopic, demixing, shooting, non-flowable or pasty bulk materials is the host (especially just the right amount ), more than challenging. The above described properties can be easily removed with a Kippbalkenboden. Commodity that is weather resistant, can be stored outdoors. In the carriage, a distinction is continuous, ie uninterrupted flowing, and discontinuous transport.
The continuous transport processes include basic facilities such as hoses and pipes (called pneumatic transport ), but also complex systems such as continuous conveyor belt ( troughed belt, conveyor belt ), chain elevators and conveyors, vibratory conveyors and bucket elevators and rotary valves for discharging and metering. Furthermore, the double pendulum flap is used for the transport of coarse bulk material. Discontinuous transport occurs in bulk silos or bunkers ( as in ships, there referred to as Stürzgut ) in hollows and high-sided vehicles ( road and rail), as well as in Silo, tank trucks, semi-trailers with sliding floor and in bags or in big bags.
Schüttguttechnik
In bulk solids technology to deal with the functionally appropriate design of equipment in mechanical process engineering, in particular silos. Through knowledge of experimentally determined bulk material properties, a silo with the aim of avoiding discharge disorders such as holing, bridging or segregation is possible.
Experimentally determined properties are:
- The unconfined yield strength,
- The bulk density,
- The effective friction angle,
- Angle of wall friction