Corrosion Characteristics Of Material In Treated Refinery Wastewater

At present, there is a large number of low temperature waste-heat in the refinery which is not used. The quantity of discharged wastewater in the refinery is large, so the recovery of the low temperature waste-heat and wastewater will improve the energy and water utilization efficiency. Low temperature multi-effect desalination has a series of advantages, for example, it can recycle the low temperature waste-heat, the quality of produced water is also good. The low temperature multi-effect desalination not only can be carried out on the low temperature waste heat recycling, but also can be used to recycling water as a source of the refinery industrial water. Due to large fluctuations in water quality of the treated refinery effluent wastewater and the complicated composition of wastewater, it’s important to pay attention to the metal corrosion in the refinery wastewater when applying the low temperature multiple effect desalination on recycling wastewater. In this paper, the corrosion and scaling characteristics of material in treated refinery wastewater were studied, which provides the basis for selecting material in the design of low temperature multi-effect.Combined with the actual situation in low temperature multi-effect evaporator the value of LSI, RSI and PSI index which is used to judge calcium carbonate scaling tendency are calculated in the treated refinery effluent wastewater. The results show that with increasing temperature and rising concentration ratio, the water tends to increase the occurrence of fouling. With increasing the number of effects, the calculated value of LSI index increases, the calculated value of RSI and PSI decreases, the results show that with the increase of the number of effects, the occurrence of fouling tendency is growing, the calculated value of three index show that it’s easy to occur severe fouling effect in the sixth effect of evaporator. To prevent serious fouling phenomenon and affect the heat transfer coefficient, taking appropriate measures is necessary.In order to investigate the effect of temperature and concentration ratio change on the material corrosion in the low temperature multi-effect evaporation process, this paper investigated the corrosion behavior of304,316stainless steel and HA177-2aluminum brass in the treated refining wastewater by static soaking experiments, metallographic microscope and other methods. The results about corrosion rate calculated by weight loss method indicate that304and316stainless steel have good corrosion resistance, it can be used as the materials of equipment. At different temperature, uniform corrosion rate of HA177-2aluminum brass is greater than304and316stainless steel, the corrosion of HA177-2aluminum brass is more serious than304and316stainless steel, and found that at80℃, the corrosion rate in unconcentrated water samples is0.0343mm/a, according to Chinese corrosion ten degree standard, it is in the fourth degree. We can infer that the uniform corrosion resistance of HA177-2aluminum brass is available. As the temperature rises, HA177-2aluminum brass’s uniform corrosion rate rises, but increase of concentration will reduce the corrosion rate of HA177-2aluminum brass,it can be used as the first choice of heat transfer materials.In view that pitting and other localized corrosion often occurs in a chlorine solution for the304and316stainless steel, this article investigate the pitting corrosion of304,316stainless steel in treated refinery wastewater by potentiodynamic scanning. The study found that as the temperature rises, the pitting potential of304and316stainless steel decrease, the maintaining passivity current density increased, the pitting resistance ability decrease. At55°C under the chloride ion content for the8212mg/L, the pitting potential of304and316stainless steel are the least,0.12V and0.26V V respectively, the pitting corrosion resistance of316stainless steel in the treated refinery wastewater are better than that of the304stainless steel.