Technical Paper

Typical cavitation wear in swirl tube cyclones

pass between the vanes and the tube surface with high velocities.

7.3 Available armour systems for [thin] erosion- resistant refractory linings

In FCCU's erosion depends merely on the interactions of the strip thickness, the jet speed, the angle & direction of impact, the catalyst particle size and concentration, and the hardness of the substrate. The strip thickness and length should be reduced as much as possible to become less dependent on the above variables. Complete omission of visible steel parts in the surface, like e.g. V-anchors do, shall predominantly depend on the lining thickness and layout.

Hexmesh is a hexagonal shaped panel which is formed by continuous strips fitted together. Standard strip thickness is 1.5 - 2 mm and hexagons are Across-Flat [A/F] 50 or 75 mm. Refractory is commonly finished flush with the top side of the Hexmesh. Hexmesh is therefore rather vulnerable for all abrasive actions.

Flexmesh is contrary to Hexmesh rollable over one side to fit inside smaller piping, etc. where Hexmesh is not suitable anymore.

Main manufacturers are a.o.: VICO-Costacurta SpA, IT and Causeway Steel products Ltd, UK.

(Punched) Tabs, in various sizes and shapes based on the same strip type of Hexmesh, are available to accommodate the continuation of a Hexmesh/ Flexmesh armour over and around corners, angles, etc. during installation.

Manufacturer: Many suppliers.

Common V-anchors, are generally small wires of Ø6 mm, with V-shaped (corrugated) bended prongs and variable height, which occasionally surface the refractory material or stay approx. 10 mm below. They can be shaped for hand-welding as well for stud welding.

Manufacturer: Many suppliers.

Speed Cells™, with dimensions A/F 30 or 50 mm, also have a hexagonal shape but the steel thickness is 0.8-1.0 mm, and of which the upstanding 'lip', forming an interrupted hexagon, has a maximum length of 22 mm (A/F 50) surfacing the refractory material. Due to its reduced thickness, even in longitudinal direction erosion becomes very limited; catalyst particles become easily 'trapped'.

Manufacturer: Silicon B.V., NL. Speed Hex®

, resulted from a further development by Silicon NL where a

greater flexibility was achieved by changing from the existing hexagonal shapes with a centre stud to the triangles shape with (or without) the integrated stud ‘in the corner’ of a hexagonal pattern. Again where possible ‘lips’ are incorporated to improve retainability of the refractory.

Manufacturer: Silicon B.V., NL.

Main feature of Speed Cell, Speed Hex is of course the reliable and quick method of installation, i.e. by Rapid Arc Welding, contrary to time consuming forming, cutting and finally hand-welding of Hexmesh [ref 6.3].

Furthermore readers attention is also suggested to earlier publications with regards to steel anchoring and armour in refractory linings published in this Journal.

Pitfalls with steel anchorage within your refractory lining, Theron J., Refr. Eng. July 2014, p.17-20;

Pitfalls with steel anchorage within your refractory lining, Pt.2, Theron J., Refr.Eng. September 2014, p.19-21;

Pitfalls with steel anchorage within your refractory lining, Pt.3, Theron J., Refr.Eng. November. 2014, p.15-17;

Hexmesh May 2019 Issue


(Punched) Tabs 19

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