How can a cone valve as a discharge device improve residual discharge and dosing accuracy?
A cone valve is an active discharge device for bulk materials in which a conically shaped closing body is moved vertically into, or lifted out of, a correspondingly shaped valve seat at the vessel outlet. This geometry creates an annular discharge cross-section whose size can be set precisely via the stroke of the cone. This design offers substantial advantages for residual discharge and dosing accuracy in the bulk solids and process industries.
Improving the residual discharge
A flow profile that promotes mass flow
The conical contour of the valve body widens the annular gap towards the outlet and encourages mass flow behaviour: the entire product column is set in motion, whereby dead zones, core flow and bridging are markedly reduced. The bulk material is thereby drawn off across the entire cross-section instead of only via a central flow channel.
Avoidance of bridging and ratholing
Through the vertical lifting of the cone, the material is broken up mechanically directly in the core. Stable bulk material bridges above the outlet as well as ratholing are thereby avoided, which enables an almost complete residual discharge.
Active product displacement on closing
During the closing operation, the cone actively displaces the residual product out of the valve seat and outlet area. Build-up on vessel walls and in the outlet is minimised, which is advantageous particularly with cohesive, moist or poorly flowing media.
Mechanical activation and optional vibration
The stroke movement of the cone induces shear stresses in the bulk material and thereby helps to overcome internal cohesive forces. Optional vibration or pulsating stroke movements can detach adhering residues and transfer them into the product stream, whereby even critical products are discharged better.
A low-residue outlet geometry
In the closed state, the cone seals the outlet across its full area and has no horizontal edges or dead spaces. As a result, practically no product residues remain in the vessel outlet or valve area after the discharge operation, which increases the yield and reduces the cleaning effort.
Improving the dosing accuracy
An infinitely adjustable annular gap
The annular gap cross-section can be set infinitely via the vertical stroke adjustment. This enables sensitive control of the mass flow – from a coarse stream for rapid filling to a fine stream for exact final dosing. The product stream thereby becomes reproducible and readily automatable.
Coarse and fine stream dosing in a single device
A cone valve supports classic two-stage dosing strategies: first a high volume flow is realised with a larger stroke in order to reach the set point quickly, and the stroke is then reduced in order to set a small, stable fine stream for precise final dosing. Trailing quantities are thereby minimised and the repeat accuracy of the dosing is increased.
Defined closing behaviour with little delay
The centric, axially symmetrical closure ensures a readily reproducible stop of the material stream with little trailing. Since the valve closes directly in the product stream and against gravity, the material flow is interrupted quickly and in a defined manner when the target weight is reached, which reduces the standard deviation of gravimetric dosing.
Uniform discharge resistance and low shear loading
The symmetrical annular gap produces a uniform flow resistance and prevents uncontrolled surges of material or blockages. The gentle flow profile reduces segregation effects with mixtures of differing particle sizes or densities, whereby fidelity to the formulation is improved through to the end of the process.
Further process engineering advantages
- High sealing effect against fine dusts and powdered media
- Less cleaning effort thanks to product-contact surfaces without dead spaces and with little residual build-up
- Suitability for automated processes, since the stroke and opening characteristics can be controlled precisely
Through this combination of mass-flow-promoting geometry, mechanical product activation and precise stroke control, a cone valve contributes substantially to optimising both the residual discharge and the dosing accuracy in continuous and batch bulk solids processes.
How amixon® solves residual discharge and accurately dosed discharge by design
Geometry and mixing tool work together
amixon® designs the mixing chamber, mixing tool and discharge as a functional unit. In the cone single-shaft mixer AM, the conical geometry of the mixing chamber guides the product specifically to the central outlet, while the SinConvex® mixing tool not only enables the highest mixing qualities but at the same time supports complete discharge. Free-flowing goods can thereby be discharged to 99.997 per cent and better.
The KoneSlid® mixing system goes one step further. Here the lowerable closing system opens the entire cross-section, so that the batch can flow out within a few seconds, without a cone of repose and without a segregation path. The discharge is therefore particularly rapid, uniform and reliable.
The cone closure as closing device, dosing device and mixing tool
At amixon®, the cone closure performs several tasks at once. It acts as a tight closing device, as a precise dosing device and at the same time as a static mixing tool that has a favourable structural effect on the discharge area. Dead spaces are thereby avoided, the material flow remains controllable and the residual discharge is integrated into the discharge rather than compensated afterwards.
Dead-space-free discharge devices with a dosing function
Available as discharge devices are dead-space-free standard connections with a discharge flap as well as vacuum-tight and pressure-tight ball segment valves. Similarly to the DosiFlap® system, accurately dosed filling of big bags and containers directly from the KoneSlid® mixer is possible, without an intermediate vessel and without a segregation path. The discharge device closes flush with the inner wall of the mixing chamber, so that no dead spaces arise above the fitting in which residual quantities could remain.
The economic effect
A high residual discharge means less product loss per batch, less cross-contamination when formulations are changed and shorter cleaning. Good residual discharge saves time and money every day, and with high-value formulations this design advantage pays for itself very quickly.
Manufacture in Paderborn as the quality foundation
amixon® develops and manufactures exclusively at the Paderborn works with a high depth of manufacture and all components from Germany. As a certified welding company with European, Japanese, Korean and American qualifications, amixon® designs every apparatus as a one-off on the basis of the operator's URS, and quality control remains entirely in-house without gaps.
Qualifiable and documented
For regulated environments, amixon® supplies the plant in qualifiable form. Every apparatus is a one-off in accordance with the URS from its own production with quality control that has no gaps, and amixon® assists on request with DQ, IQ and OQ. On request, the mixers meet relevant standards such as EHEDG, the FDA hygiene guidelines, the 3-A Sanitary Standards, USDA, GMP, ATEX and ASME.
Verification in the amixon® pilot plant
amixon® checks in advance in the pilot plant, with 35 test units, whether the specific formulation delivers the expected results. Trials with the original product under real conditions are carried out, evaluated and documented jointly and serve as a robust basis for decision-making before the investment.