Cold water side stream filtration package for Shell’s Ethylene Cracker Complex in Singapore

Cold water side stream filtration package consisting of DynaSand internal filters. The wash water from the DynaSand filters is processed by Lamella plate packs and Zickert bottom sludge scrapers. The entire system is built in concrete tanks.

Shell case

The challenge
The Ethylene Cracker Complex (ECC) is a petrochemicals plant in Singapore that produces 800,000 tonnes of ethylene, 450,000 tonnes of propylene and 230,000 tonnes of benzene a year. The plant is connected to the Pulau Bukom refinery, which is owned by Shell Eastern Petroleum (Pte) Ltd. Vast amounts of water are required to keep the plant cool, and this water needs to be purified. The facility is built on reclaimed land, which means that space is limited.

The solution
ABB Lummus Global (now CB&I) granted Nordic Water Benelux BV the task of preparing the basic design for the cold water side stream filtration package.

Based on this, an order was placed for DynaSand filters, Lamella plate packs and a Zickert bottom sludge scraper.

The result
The cold water system for Shell ECC in Singapore is an open circulation system with a
cooling tower that uses an evaporative cooling method. Fresh water circulates in an open circuit and is cooled in the cooling tower. Water is fed into the cooling system through pipelines from mainland Singapore and blow down is directed out to sea.

To prevent the cold water system from becoming excessively polluted, 2-3% of the pumped, circulated cold water is channelled over the side stream filter system in order to remove any suspended solids (e.g. dirt, corrosion products). The outflow from the filters is fed back into the cold water tank. The wash water is processed by plate packs and the treated effluent water is fed into the cold water tank. The sludge is removed by the Zickert scraper and channelled into a centrifuge.

Once the system had been put into operation, it soon became apparent that it was working even better than expected. See below for some more information.

Technical data

DynaSand filters:
– Average flow rate: 1,687 m³/h, maximum flow rate: 1,800 m³/h
– Inflow TSS: < 50 mg/l - Outflow TSS: < 15 mg/l, values between 5-10 mg/l normally achieved Lamella plate packs and Zickert bottom sludge scraper: - Flow rate: 120 m³/h - Inflow TSS: < 500 mg/l - Outflow TSS: < 25 mg/l, values of < 20 mg/l normally achieved Installation: - 30 DS6000AE-B DynaSand internal filters, five tanks with six internal filters each - Two Lamella plate packs (type LP140/140-05) - A Zickert bottom sludge scraper (type Z2011, 8 x 3.5 m)

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