Research On The Oil Sludge Dynamic Washing Bythermochemical Method

Oily sludge is one of the major pollutants in the oil production process.Oil sludge has the characteristics of large production volume and high difficulty in handling oil.If it is piled up without treatment,it will not only cause environmental pollution,but also cause waste of crude oil resources.Therefore,in this paper,the composition and physicochemical properties of the oily sludge were studied for the oily sludge in Daqing Oilfield.Based on this,the simulated oil sludge was formulated to study the effect of various process parameters on the deoiling effect in the cleaning process.Good process conditions.The process of thermal chemical dynamic cleaning of oil-containing sludge was designed.The cleaning agent of oily sludge and the flocculant processed by the subsequent cleaning fluid were screened and compounded to determine the best cleaning agent formulation and formulation of flocculant.Experimental results show that:The three component ratio of water,oil and solid in oily sludge is 34.63%:19.32%:46.05%.The four component ratio of fat hydrocarbon,aromatic hydrocarbon,colloid and asphaltene in crude is 51.2%:26.8%:15.8%:6.2%;The ratio of gas,liquid and solid phase in oily sludge pyrolysis product is 15.6%:37.7%:46.7%.The major constituents of gas phase product is combustible gas.The major constituents of liquid phase product is light hydrocarbon with C₇^C₁₅5 and fatty hydrocarbon and aromatic hydrocarbon content is main.The solid product composition is complicated;Oily sludge heat weightlessness process is divided into four stages:<160?,evaporate of moisture and part of the light hydrocarbon,160⁴70?,hydrocarbons evaporation,470⁶50?,pyrolysis of heavy component,>650?,calcination of sludge residue.The nature of simulative oily sludge is the most stable and similar with oily sludge when the three component ratio of water,oil and solid is 34.63%:19.32%:46.05%.Within the scope of the test,The optimum conditions of Thermochemistry-Ultrasonic Dynamic Cleaning System:the ratio of oily sludge and the cleaning fluid of 1:5,the pH value of 8,washing temperature of 40?,the stirring speed of300r/min,washing time of 20min,the oil removal rate was 81.23%.The oil removal rate of Chemical cleaning obviously higher than pure water cleaning.The lower the frequency and the higher the power of the ultrasonic wave,the more effective the degreasing effect.The oil removal rate can reach 94.26%,when sodium silicate:SP169:AS-1=40.0%:30.0%:30.0%,sum dose of 3mg/L;The secondary cleaning process was simulated in the room and the oil removal rate only increased by 0.51%.For this oily sludge,the primary cleaning can meet the emission standards;The most effective flocculant is polyaluminium chloride and cationic polyacrylamide.When the PAC is 8mg/L and CPAM is 80mg/L the oil removal rate can reach 88.72%,the effect is better than single dose treatment.The mixed agent composed of sodium silicate,demulsifier SP169 and AS-1 can effectively reduce the interfacial of tension three-phase,making the oil in the liquid phase of the oil-containing sludge clean and emulsified,and greatly reducing the in-phase The electrostatic resistance facilitates agglomerating into large particles and eventually separates and removes oil.PAC is used as inorganic polymer flocculant,its molecular formula is[Al₂?OH?_nCl_6-n]_m.These complexes have a large net structure and can sweep flocs in the flocculation process.Additionally,PAC can form positively charged complex compounds through hydrolysation,which diffuses to the interface and are characteristically absorbed onto the double layer at the oil-water interface.These adsorbed complex compounds can neutralize some of negative charges on the oil-water interface.CPAM is a cationic flocculant that can neutralize negative charge of oil drops and lower zeta potential and electric double-layer thickness,reducing the repulsion between the oil drops and destroying their stability.The effects of polymer molecular weight on flocculation are best described in terms of bridging and electrostatic patch character mechanisms,which help the resulting flocs to become larger,allow their aggregation with each other.With the combined use of PAC and CPAM,more positive charges are integrated into the floc hydroxide,which is capable of electrostatic adhesion.