April, 2022

Cooling tower refurbishment for fertiliser plant

IWC are currently in the process of finalising the refurbishment of 2 cells of a larger 12 cell forced draught cooling tower. With civil repairs completed, all that’s left is to install a fibreglass liner (corrosion barrier) whereafter the internals are to be fitted. The fertiliser plant is one of the major suppliers of granular fertilisers, namely diammonium phosphate (DAP) and monoammonium phosphate (MAP), core ingredients in final fertiliser products comprising nitrogen, phosphates and potassium, also known as NPKs in South Africa.

The phosphate rock concentrate, a key input in phosphoric acid production, is railed primarily from Phalaborwa to Richards Bay. Richards Bay is one of the country’s largest harbours and interestingly, it is also the deepest natural harbour on the African continent.

Requirement

The 12 cell, forced draught concrete cooling tower was in a poor state of repair. Severe clogging of the internals had occurred due to the nature of the process solution as well as the harsh site-specific ambient conditions.

Solution

We partnered with a local civil specialist repair contractor to undertake the civil repairs on our behalf.  The concrete and steelwork was reinstated using suitable modern repair materials and methodologies that considered the aggressive operating conditions of the plant and would thus ensure the mechanical integrity of structure going forward. The existing fibreglass liner also had to be repaired and reinstated in many areas, requiring adequate surface preparation and strict quality control with respect to the application thereof.

The severely clogged internals were stripped and safely disposed of. The existing fibreglass liner was then inspected, and all damaged areas removed exposing the deteriorated concrete substrate. Civil repairs were carried out, and the re-application of a suitable fibreglass liner was undertaken. A new treated timber structure with exotic stainless steel fasteners was installed; ideally suited for the corrosive process water and ambient conditions. A new fibreglass water distribution trough system with purpose made polypropylene sprayers was installed on top of the timber structure. The fill consists of treated timber splash bars to ensure that clogging is kept to a minimum. New PVC drift eliminators with clipped polypropylene spacers were also installed at the top of the cooling tower.