Research On Hydrothermal Decreasing Technology Of Dehydrated Oily Scum

Oily sludge produced in the process of oil-wastewater treatment in petroleum exploration and petrochemical industry,which belongs to hazardous solid wastes and has complex composition and serious emulsification.Its dehydration and drying treatment is the bottleneck of treatment and resource utilization,and has become a difficult problem that must be solved for the sustainable development of petroleum and petrochemical enterprises.This topic aims at the oily scum after centrifugal dehydration in the 91 oil wastewater treatment plant of Heavy Oil Development Company in Xinjiang Oilfield.The combined process of hydrothermal conditioning and destabilisation,flash evaporation and mechanical dehydration technologies to treat the scum is designed.It can simultaneously realize sludge dehydration reduction and mineral oil recovery.The results show that the optimum operating parameters of hydrothermal treatment are170?,reaction time 30 min and stirring speed 150 r/min.The best cooling method is flash evaporation.The optimal mechanical dehydration method is centrifugal dehydration.After hydrothermal deweighting treatment under the best process conditions,the water content of oily scum is reduced to about 50%,and the reduction rate is over 55%.SEM,EDS,particle size,FTIR and four-component analysis were used to characterize the structure and component determination of sludge flocs before and after hydrothermal treatment.It was concluded that the combined water in sludge flocs was transformed into free water or interstitial water,and the dehydration performance was greatly improved.The concentration of organic matters in the separation liquid is high,and the content of Ca²⁺and other elements in the hydrothermal residue is greatly reduced,which proves that some inorganic salts and organic matters in the oil sludge are dissolved.The oil recovered by flash evaporation has a high content of light components,and the high content of CO₂ and low carbon hydrocarbon components in the gas indicate that the organic matter has cracked and hydrolyzed.Hydrothermal method is a good technology for condition and destabilizing for high water-contain oily sludge.It can not only improve the dehydration performance of water contain oily sludge,but also realize the effective recovery of mineral oil,which is conducive to subsequent dehydration and drying treatment.