DASAG GmbH Verfahrenstechnik + Anlagenbau

Big Bag Metering Station

A multitude of manufacturers offer equipment for emptying Big-bags. When you get a general idea on all that you will find some greater differences between the several concepts. This is largely due to the customer’s specifics. It becomes especially complicated when you have a so-called “problematic” bulk material. Imagine some properties like bad flowing, bridging, cohesive, fibrous or blocking. Additionally the emptying of the Bags is not the only imperative. Mostly the material has to be conveyed to the further use, if possible weighed and metered also.

There are some invaluable advantages when all technique comes from one source – an in this special case everything is combined in one compact device.

The objectives of this new DASAG development were set clearly:

•  Steady metering
•  Dust-free handling within a closed system
•  Adjustable flow volume and flow velocity
•  Partly emptying of the Big bags
•  Possibility to feed back the excessive material into the big bag
•  Flexible, autarkic concept of design

The way of solution was to design a metering unit with the Big bag as a flexible weighing container as well as an integrated powder pump.

The plant consists of the following essential parts and functional groups:

•  Load lifting cross with docking connection and filter bag
•  Big bag receiving frame with integrated guide sled
•  Receiving table for Big bag
•  Receiving construction for the docking system and the powder pump, altogether designed as a weighing frame
•  Hand-operated on-docking system with passage adapter to the powder pump
•  DASAG Powder pump with weighing compensator after the pressure spout
•  Control system with SIWAREX module and a SPS S7-300 with OP3 panel to control all functions of the plant.

Recapitulating, it is to notice that this metering system bases significant upon the advantages of the powder pump because the preparation of material as well as the steady conveying runs over the pump. If you consider the complete system especially concerning the extensive use for a wide range of bulk material, then you will find some further advantages which have not been mentioned as yet. We remember the suction effect of the pump, the permanent pressure monitoring, the optimal material load with absolutely low pressure in the line, the low air volume in the conveying flow and connected with this the small de-dusting equipment, the possible operation with inert gas. Of course some special functions are to be adjusted closely to the respective bulk material. This is possible about the DASAG controls with access to approved function programmes for different product groups. E.g. the mode of action of pneumatic or mechanical discharge assistance can be modified for highly different materials. Anyway a universal and flexible application of the proposed system for a wide range of bulk material is possible.

DASAG Powder Pump – News and Advancements

Within the last years conventional double membrane pumps have been employed increasingly for the pumping of powdery bulk materials. The relatively slow and gentle discharge with a small air share and, at least partly, the suction mode of these pumps account decisively for this development. The pumping of bulk materials with simple membrane pumps, which are mainly employed with liquids, does usually only work with fine powders with a relatively low bulk density. But a multitude of powders and mixtures show bulk densities of > 500 kg/m³ and partly bulk characteristics which do not allow discharge via simple membrane pumps.

The clear advantages of being able to pump even such bulk materials were the initial point to de-velop a special pump for powdery and granular bulk materials based on the system of the mem-brane pump. Electro-pneumatically actuated valves were installed at the in- and outlets of the pump chambers and the pump cycle was controlled. Connections for controlled air supply and pressure control were established at suitable positions at the pump chambers and in the outlet area. The general flow direction through the pump was set from top to bottom in gravity direction in order to reach a certain self-fluidisation of the material when in free fall. The entire system is controlled by a programmable control system. Various adaptable programmes allow an optimal adjustment to the respective materials and conditions.

The DASAG pump systems have conquered a remarkable position on the market within the last 10 years. Simultaneously the powder pump has been enhanced according to the very special requirements of the customers. This is subject of the following: A controlled air supply is given in order to keep the materials in a state where they can be pumped. The gas share of the flow is to be kept as small as possible. This is especially important with materials which are to convey with inert gas and subsequent preparation procedures of the gas phase. If required you can separate the driving air from the fluidising air or inert gas. This could be important for customers with poor air supply because they can feed in with two different pressures. Moreover you can agitate complicated bulk material by special pneumatic or mechanical devices so that it flows into the pump chambers. In a lot of cases it is verified that the powder pump is the perfect conveyer for complicated bulk material such as structure-sensitive, bridging, fragile, cohesive and adhesive.

The flow volume of these versatile compact pumps is approx. 3 - 4 m³ for distances up to approx. 40 m with powdery bulk materials with bulk densities of approx. 1,000 kg/m³. With optimal bulk ma-terials and transport systems higher flow rates and longer distances are possible. To increase the capacity the “Duo Pump” was developed with two identical pump blocks.

Meantime there are various designs of the powder pump, e.g.

• with suction amplifier to suck material from several stations and pump it into other stations.
• Pump combined with container weigher
• With variable product inward transfer (smallest components)
• Pump as tie-in point, especially in metering plants
• Equipped for explosive regions
• Combined with sac-, bin- or IBC-discharger
• As above, additionally the complete unit is designed as a metering device (see adjoining pic-ture).
• Application for IBC or container filling

Powder pumps are often a part of complete systems for the transport of bulk material in dosing, mixing, packaging and recycling plants in many lines of business.

Dosierung von Chromat-Reduzierern in Zementanlagen

Kleinkomponenten-Dosierung in Mischprozessen