Study On Online Removal Of Oil From Refining Circulating Water

During the circulating water system of petrochemical enterprises operation process, often have oil leaks into the system, the oil formed in the metal surface of the device, resulting in lower equipment heat transfer efficiency; adsorbed by the circulating water of suspended solids and colloidal particles formed on the surface dirt, resulting in increased corrosion of the equipment; the existence of petroleum substances also encourages the growth of bacteria and algae, water quality deterioration. At the same time, the filter packing can easily be compacted by the oil-leakage and cleaning is very difficult. At present the usual treatment is injecting replenishment or drainage replacement in circulating water system, thus, causing the water reuse rate is low, wastewater emissions increase, sewage charge rise and wastewater treatment plant production load heavier. Until effectively implemental the national environmental emission reduction policies and develop recycling economy, where more rational use of water resources, reducing wastewater. Therefore, it needs to find an effective solution to this problem. This article study the feasibility, the influence factors and optimum process parameters of the coagulation-air flotation used in refining enterprise circulating cooling water system of oil water treatment, achieved good results in the lateral line amplification test. The study results will be provide a basis reference and technical support for circulate cooling water reuse project of petrochemical enterprise.In this experiment, using the coagulation treatment on oil-containing circulate cooling water. Research indicated that, when the PAC/CPAM dosage respectively is60mg/L and1.0mg/L, the fast stirs speed is300r/min, the fast stirs time is60s, the slow stirs speed is60r/min, the slow stirs time is10min and the settlement time is20min is the best experimental conditions, turbidity water, oil content and CODcr respectively is1.98NTU,1.15mg/L and25.91mg/L. Although coagulation method has good treatment effect, but due to the longer processing time, large dosage and residues difficult to treat as existence of these problem which need to be improved. Therefore, on this basis, using the coagulation-air flotation to experiment of oil cooling water circulation is a good choice. The experimental results showed that when the PAC and CPAM was formed a composite drug, oil removal efficiency is up to84%, the CODcr removal rate more than up to89%and the turbidity removal efficiency higher than95%, after treated the water quality was achieved to reuse requirements by the coagulation-air flotation. Subsequently, use of coagulation-air flotation in the lateral line amplification test, after the treatment, turbidity water quality reduced from76～105NTU to3.0NTU, the removal efficiency of up to95%; suspended solids content from85～102mg/L reduced to4.0mg/L below, suspended solids removal efficiency of greater than95%; oil content from19～29mg/L reduced to30mg/L, the removal efficiency of up to85%; CODcr from70-78mg/L reduced to12mg/L below and removal efficiency of greater than82%. Water quality key indicators are significantly better than "sewage reuse engineering design standard"(GB/T50335-2002) related index requirements, while also achieved the stable of a petrochemical company "renewable water circulation index requirement", especially oil water content of circulating water which influence of the water system was reduced and operation test achieved the expected effect.