Stirred, Not Shaken: Three Ways to Maximize the Lifetime of Agitator Parts

Related Vendors

Glatt Ingenieurtechnik GmbH

Italvacuum, Srl

Angst+Pfister AG

EKATO Process Technologies GmbH

Measure 3: Ceramic Components

In addition to the possibilities described above to increase equipment service life, it is also possible to manufacture impeller blades or complete impellers using solid ceramic components. As opposed to coatings, a solid construction offers the advantage that the same surface hardness exists throughout the entire component. Then once the protective coating is worn off, the base material will again be subject to high wear rates.

Complex geometries can be manufactured thanks to recent developments in the field of ceramic materials and their improved processing options. Nevertheless, it is still especially important to exactly know the hydraulic and vibrational loads on the agitators when designing impellers using brittle ceramic materials.

These are decisive factors for an operationally reliable design. A ceramic-compliant design of the composite — metal and ceramic — or solid structures is a critical factor for the technical feasibility and economic viability of the project. When designing industrial impellers, composite structures are usually used where only the wear-exposed areas are designed of solid ceramic components. Those areas that are not so affected by abrasion — for example blade holders, hub and hub connections — are made of metallic materials.

Gallery

It is possible to compare uncoated, coated and solid ceramic components with each other in regard to their abrasion behavior on the basis of pilot wear tests at the Ekato test center in 1 m³ scale. Based on measurements, it was possible to draw conclusions concerning the relative wear resistance of the materials and their differences in service life. A comparison of solid ceramic components with coated components revealed that the lifetime can be increased by a factor of 10 to 15 with solid ceramic components. The use of advanced ceramics is not only worthwhile in areas where components wear out very quickly and plant shutdowns cause high costs, but their use is equally attractive if metallic attrition or dissolved metal ions due to corrosion are not permitted. Highly pure and fine-particle silica serves here as an example.

Summary

Impeller wear is a frequently encountered problem in mixing applications. The lifetime of agitator parts can be extended using the measures described. The increase in cost and time pressure during maintenance work can make an investment using impeller coatings or ceramic materials profitable within a short period of time. Apart from the direct investment for parts to be replaced, downtime costs can be reduced and unplanned breakdowns caused by wear issues can be avoided. Ekato offers for this purpose individual, custom-made solutions. These range from an optimization of mixing processes based on tests in pilot plants and the scale-up to industrial scale as well as an operationally safe design of all agitator components and the vessel.

* B. Multner is Head of Mechanical Development R&D and W. Keller Senior Process Engineer R&D at Ekato, Schopfheim.

(ID:44238699)