Flowserve Delivers Valve Solutions

Complete controls assembly for Imerys tube presses

A major operational re-structure at Imerys Pigments for Paper has seen a large part of the company’s Cornwall production facilities re-focused on the production of high-volume paper filler kaolins.

Imerys’ Pigments for Paper unit is a world leading producer of white pigments, such as kaolin ground calcium carbonates and precipitated calcium carbonates. Its Cornwall facilities are particularly well suited to the production of filler grade material used in a range of papers which make up magazines, newspapers and catalogues across Europe.

In concentrating filler production at St Austell, Imerys invested significantly in new clay drying plant to improve the production processes. China clay production is a mining process involving the washing of clay out of altered granite rock. After processing, the feed material has a very high water content which is reduced through use of a tube filter press.

The press consists of two tubes one inside the other, with an internal space between them, except at the bottom where the inner tube is bell shaped to fit closely within the outer tube. The inner tube contains drainage holes and is covered with a filter cloth. The outer tube has a tubular rubber bladder inside it. Clay is pumped into the space between the filter cloth and the rubber bladder. Hydraulic fluid is then pumped into the space between the outer tube and the rubber bladder. This compresses the clay and forces water through the filter cloth. The advantage of this method, is that very high pressures of up to 100 bar can be used and the filter cake can be reduced to 18% water content. When the pressing cycle is complete, the inner tube can be lowered slightly within the outer tube and the clay cake is pushed off by compressed air.

As part of the restructuring project Imerys commissioned 120 new tube presses at its Rocks plant near St Austell. A key success factor was to design an efficient, resilient mechanism to control the ingress of slurry and the egress of water drained from the tube pressing process.

The company turned to Flowserve Flow Control who, with many years of experience of working with Imerys, produced a modified ball valve and actuator design which featured Flowserve Worcester A44 series valves and Norbro actuators with:

. UHMWPE valve seats to provide abrasion resistance
. Special hardened matched ball and stem to handle the highly abrasive slurry and high cycling duty
. High tensile strength valve stems
. Bespoke high cycling stem build

A key feature of the solution is that for each tube process, Flowserve was able to supply Imerys with a bespoke valve manifold and pneumatic control design, which was pre-mounted, assembled and tested as one complete unit. This solution was identified as a far more cost-effective proposition than a fabricated assembly.

Particularly important to Imerys was Flowserve’s ability to produce 3D solid modeling of the assemblies as their design evolved and their subsequent ability to integrate the models into their own plant layout designs.

This highly collaborative approach meant that the 120 valve/actuator packages and manifold assemblies were all delivered on time and achieved significant installation cost savings for Imerys. Subsequently the success of the Flowserve solution has been recognized by orders for a further 33 manifold assemblies for a plant upgrade at Imerys’ facility in Brazil.

Flowserve Flow Control,
Tel: 01444 314400
Website:
www.flowserve.com

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