| Oil-bearing sludge is a kind of hazardous solid waste containing a large amount of hard-to-degrade organic substances,heavy metals and toxic and harmful substances generated during the process of oil extraction,processing and transportation.Oil-bearing sludge with petroleum pollutants is one of the important indicators of oil-bearing sludge treatment,and the tempering-centrifugal separation process can effectively dewater and remove oil from oil-bearing sludge,which is in line with the national green development concept.In this paper,firstly,the physicochemical properties of the oil-bearing sludge from an oil-bearing sludge treatment station in Daqing oilfield were analyzed,in order to understand the nature of the oil-bearing sludge and lay the foundation for the subsequent screening of chemicals.Single-factor experiments were also conducted to determine the initial experimental conditions and to establish the scope for orthogonal experiments.The effect of the type of agent and its dosage application sequence on the tempering effect was examined,and the intrinsic effects of temperature and mixing time on the tempering effect were also analyzed.The study showed that the best conditioning effect was achieved when the flocculant Polyacrylamide(PAM)and the emulsion breaker Sodium Dodecyl Benzene Sulfonate(SDBS)were used together,with the optimal dosage of PAM being 0.006 mg/g and SDBS being 0.08 mg/g.The best dosage of PAM was 0.006mg/g and the best dosage of SDBS was 0.08mg/g,and the flocculation and demulsification of the sludge was more beneficial when PAM was applied first and then SDBS.Then,based on the two-phase flow model of oily sludge solid particles and water,COMSOL software was applied to numerically simulate the mixing behavior of sludge and water in the homogenization tank and the mud-water separation characteristics in the centrifuge.It was found that the mixing speed,sludge-water ratio and mixing time play a decisive role in the mixing of sludge and water,the larger the mixing speed the stronger the vortex generated and the easier the mixing of the two phases,increasing the sludge-water ratio can reduce the viscosity of sludge and also promote the mixing of sludge and water,while the longer the mixing time the more uniform the mixing of sludge and water.In addition,increasing the centrifugal speed and centrifugal time within a certain range can improve the mud-water separation effect in the centrifugal process,and the optimal centrifugal speed is2600r/min and the optimal centrifugal time is 10 min.In addition,the optimal conditioning temperature was 50 ℃.After adding PAM and SDBS,the oil removal rate of the sludge was 87.05% after centrifugation by only heating to50℃.The oil removal rate of the oil-bearing sludge increased very little when the temperature continued to increase under the same conditions.When the centrifugal speed was 2600r/min and the centrifugal time was 10 min,the oil content of the sludge after centrifugal treatment decreased from 221.77mg/g to 28.72mg/g,which was in line with the emission standard stipulated in the new national standard "Control Standard for Agricultural Sludge Pollutants"(GB4284-2018).Based on this,the sludge-water ratio was increased to 1:5,and the oil content of sludge was reduced from 230.75mg/g to 22.36mg/g after centrifugal treatment,and the oil removal rate was increased by 3.26%.The research results of this paper can enable the effective treatment of oil-bearing sludge generated from oil fields,provide a new solution for oil-bearing sludge treatment technology,and advance the development of oil-bearing sludge tempering-centrifugal separation treatment technology.The oil substances separated by tempering-centrifugal separation treatment can be recycled,which realizes the recycling of resources and conforms to the national green development concept. |
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