In a notable feat of process engineering, Arvand Petrochemical Company has carried out the in-line dredging and sludge removal of its cooling tower basins without halting operations, utilizing a novel Air Lifting Pump system to maintain continuous production and operational efficiency.
The company operates two cooling tower units with cooling capacities of 12,000 and 16,000 cubic meters per hour, respectively. After nearly 14 years of uninterrupted service, significant sludge and sediment accumulation at the bottom of the cooling cells had begun to impair thermal performance. With the strategic importance of maintaining uninterrupted national PVC production, the company opted for a live-cleaning approach.
The operation was executed using an air-lift technique, whereby suction arms extracted the sediments from the bottom of each cell, transferring them to sedimentation tanks. There, polyamide was added to the water-sludge mixture to facilitate clarification. The thickened sludge was then collected in jumbo bags for disposal. The process was performed incrementally, cell by cell, ensuring no impact on cooling performance or plant operations.
The entire project — from design and engineering to execution, supervision, and operation — was fully developed and implemented by the company's in-house process engineering team. The solution was achieved without the use of high-cost mechanical tools or traditional pumping systems. Notably, the treated water was clarified with no additional energy consumption and returned to the cooling cycle.
The Air Lift technology, which operates on the principles of fluid transfer through compressed air pressure, offers a cost-effective and corrosion-resistant alternative to conventional dredging systems. The successful deployment of this method at Arvand has preserved process continuity, reduced production downtime costs, enhanced thermal efficiency, and lowered structural corrosion risks in the cooling system.
This innovation is considered a replicable model for other petrochemical complexes across the country facing similar operational maintenance challenges.