Study On Treatment Of Oily Wastewater By Coalescence Technology

At present, most oilfields in china have entered into mid-late oil exploitation stage. Crude oil moisture content was generally 70-80%, even reach 90%. Large amount of oily wastewater was produced from oil-water phase separation process. Discharge of untreated wastewater would put hazardous risk to environment and public health. Therefore, development of highly effective economical treatment and reusing technologies has become an important problem of the modification and establishment of oily wastewater processing station. The per-treatment of oily wastewater by coalescence can reduce the oil content greatly, and then secondary and deep treatment can make oil content and other indexes reach the standard of water quality for reinjection in the low permeability oil reservoir.Through the comparison experiment on the selection of coalescence material and reactor type, this paper discovered the efficiency of coalescence of ceramic packing is better than others significantly, and the oil removal efficiency of heap type reactor is higher than swash plate type as well as effective particle velocity period. The mechanism and reaction dynamics of coalescence were explored through the experimental results. Results showed that as the collision coalescence and the wetting coalescence mechanism were coexistence and the efficiency of coalescence was enhanced remarkably. The surface property and spatial constitution form of the fillers had important effect on the oil removal efficiency of coalescence.In order to understand coalescence technology more clearly, the experiment of influence factors was carried out. The results showed that there will be better efficiency of coalescence at particle size of l~3mm; alkaline condition and high temperature favored coalescence reaction; up-flow direction can accelerate coalescence; it's resulted the better efficiency of coalescence at 6m/h.Combined with the parameters determined by experiment, internal recycling continuous flow reactor for coalescence was designed. The oil removal efficiency of this reactor can be high up to 80% for over 12 hours, when particle size of ceramic packing at 1.6-3mm and the velocity of the up-flow at 6m/h. Otherwise, it takes about 20 minutes to make the total packing layer clean by backwashing, and 5-8 minutes to backwash the effective packing layer for coalescence.Compared with traditional coalescence equipments, this equipment has advantages of larger capacity of pollutant removal, longer period, and no medicine needed. The oil content in oilfield water treated by the equipment was greatly decreased, which relieved the loading of the sequenced processes, and the quality of the effluent water satisfied the higher requirement of injected water in exploiting low-permeability reservoir.