The flow rate of bulk solids can be determined by dosing processes. Also the total amount of the product is measured. For the dosing it is essential that enough product is available.
Continous dosing of free flowing products
Fig.4: Installation of Flow Controller FC3 with the advantage of low height
Dosage usually takes place at an outlet of a silo or container. In many cases there is not many space inbetween outlet port and conveyor (chain conveyor, elevator, e.g.). The overall height sometimes allows less than 30 cm of space. Because of this problem, we constructed a feed gate, which has a height of 135 mm if the outlet is quadratic or a hight of 220 mm if the outlet is round.
Bag filling of free flowing products
Big bag filling and emptying for free flowing products
Continuous dosing of heavy flowing products
Fig.3: control circuit of cohesive bulk solids Besides registration of quantities the dosage plays an important role in processing of bulk solids. Usually the dosing is performed by a volumetric controlled screw. Therefore it is necessary to assume a constant density of product. Effectively most products do not have constant density. To achieve an exact dosage a scale is necessary.
We realise gravimetric dosing of heavily flowing products by
- measuring the weight of bulk-flow with the Rotor Weigher and
- derously driving a screw or volumetric conveyor (depending on attributes of product and constructional conditions).
Regulation (including input of target capacity) and evaluation is performed by an electronic, easily to handle. An intergrated controller adjusts a frequency converter (FU) which drives the rotation speed to the target flow. The result is an exact continuous dosage of heavily flowing products.
By Realization of such a dosing system it is possible to produce blendings continuously. Thereby it is possible to continuously weigh, dose and blend heavily flowing products in one process step. By input of percentaged proportions, individual material flow lines can be determined accurately. Using the weighing signals, the evaluation electronic regulates the t/h flow rate, which is conveyed by the screws. Subsequently these material flows are being merged. The proportion ratio is already accomplished.
An advantage of this method is the immediate homogenization: Compared to batch mixers, which are filled consecutively and – initially – inhomogeneously, these lines are merged online. This largely reduced energy costs. Also a combination of this method with batch mixers is possible and can help to reduce the mixing costs.