Centrifugal Reduction Treatment Process for High-Water-Content Sludge in Oilfield

Abstract

To ensure that injection water quality reaches the standard, oil field sewage stations adopt a continuous sludge dredging process to reduce the content of suspended solids and sand. A large amount of highwater- content oily sludge is produced, which results in increased costs of transportation and subsequent harmless treatment. Therefore, a sludge reduction treatment is necessary. A set of centrifugal reduction processes for oily sludge was designed in this study, with the horizontal screw centrifuge as the key piece of equipment. In the laboratory, CPAM flocculant was screened. In the field test, the effects of four factors rotational speed, differential speed, the feeding quantity of sludge, and flocculant dosage on the reduction effect were determined. The results show that when the rotational speed is higher, the differential speed is lower, and the feeding quantity of sludge remains lower, and the flocculant dosage remains higher, after treatment, the water content of the sludge is lower and the solid content of the sludge is higher. The optimal parameters of the centrifugal reduction process were determined using an orthogonal experimental design as follows: rotational speed 2,607 rpm, differential speed 8 rpm, the feeding quantity of sludge 7 m3/h, and flocculant dosage 100 g/m3. After treatment, the average water content of the sludge decreased from 92.75% to 56.57%, and the average solid content of the sludge increased from 2.30% to 36.72%. The split ratio of the water-outlet and sludge-outlet was in the range of 8.71:1 to 12.57:1, and the corresponding sludge reduction ratio was 89.70% to 92.63%, confirming successful sludge reduction.