Resolution of Equipment Blockage and Scaling Problems

A large manufacturer of burnt dolomite and furnace refractories was experiencing severe problems with its recently installed dust and fume scrubbing equipment on its dolomite roasting kilns. Dust removal efficiencies were inadequate and the units were completely blocking within 1 to 3 days of start up following a thorough clean out. In addition, pipework, pumps, nozzles, filters, etc. were suffering from a combination of rapid wear and rapid building up of a very hard scale. The original equipment suppliers had been unable to resolve these problems.

RPA identified that the principal causes of the problem were a combination of a posalanic chemical reaction between the scrubbing water and the dust, carbonate based scale formation, inappropriate duct and pipe sizing, inappropriate style of venturi scrubber and inappropriate detailing as regards pipework and ductwork arrangements and componentry.

RPA Venturi Scrubber Design Concept

RPA were commissioned by the site to work with one of the equipment suppliers to re-design and rebuild one of the dust control units. The result was a greatly improved situation. However, plant operation between shut downs was still poor. As a result of ongoing active co-operation between the site engineering staff and RPA, this situation was progressively improved to an operationally acceptable performance.

This was achieved through a combination of successive improvements to the stability of the kiln, a sequence of upgrades to the method of handling the dust slurry which was created by the scrubbers and by careful attention to design details, especially at the wet-dry interface within the venturis themselves.

As a result, RPA were commissioned to design and specify new scrubbing equipment for the other operating kilns.

RPA also carried out an overall water balance for the site as a whole and developed a holistic strategy for the overall site whereby the handling of dirty surface water run off and wash down, etc. waters could be integrated with the water and solids handling infrastructure associated with the scrubbers. This strategy, when fully implemented, will make the site as a whole into a zero effluent site, should reduce the annual water supply requirements for the site by over one third and should prevent all discharges of unacceptable quality surface water to the adjacent water course, even during a very severe rain event or wet period.

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