Recycling of high temperature steam condensed water from petroleum refinery by thermostable PPESK ultrafiltration membrane

The purification and reclaiming of synthetic and industrial high temperature condensed water containing excess oil and iron is investigated in this study using thermostable poly(phthalazine ether sulfone ketone) (PPESK) ultrafiltration membranes. The results show operation parameters such as transmembrane pressure, temperature and pH of feed solution, initial oil and iron concentration each play important roles in the permeate flux and oil/iron removal efficiencies. Membrane performance is almost recovered after washing with a combination of NaOH and ethanol. High temperature condensed water from Daqing petroleum refinery can be consecutively purified using a PPESK ultrafiltration membrane. The turbidity of the solutions is almost removed. Oil and iron concentrations in the permeate solutions are below 1 mg/L and 50 μg/L, respectively, which satisfy the Quality Criterion of Water and Steam for Steam Power Equipment in China. UF process shows a promising alternative to existing technology in the Daqing petroleum refinery in terms of cost and environmental protection as well as energy recovery. For future possible combination of UF and NF process application, both economic cost and saving are evaluated, and the breakeven time is about 11 months.

► Excess oil and iron in high temperature condensed water are removed by UF membrane. ► Operation parameters affect permeate flux, removal efficiencies and membrane fouling. ► Membrane performance is recovered after NaOH in combination with ethanol washing. ► Reclaiming high temperature condensed water can prevent thermal emission pollution. ► Reclaiming it also reduces economic cost, saves energy and realizes water recycling.