Screening organic flotation agent in oily waste-water treatment

Author of the article:DONG Linlin

Author's Workplace：PetroChina Liaohe Engineering Co., Ltd., Panjin, Liaoning, 124010, China

Key Words： Organic flotation agent; Compound; Screening; Compatibility

Abstract：Flotation agent can be divided into organic and inorganic agent. The organic flotation agent has the advantages of smaller dosage, less and recyclable scum over the inorganic flotation agent. There is a variety of oily waste-water types in Liaohe oil field, and the flotation unit is usually filled with compound inorganic chemicals PAC (Poly Aluminium Chloride)+PAM (Polyacrylamide), which has high chemical cost and produces large amount of flotation scum. According to the waste-water from common heavy oil, high pour-point oil, and thin oil, screening experiments were conducted using three organic flotation agents, namely A, B(B1+B2) and C(C1+C2). The oil content and suspended solids performance indexes of the effluent outflow were measured at different retention time frame and dosing levels, and these flotation agents were also tested for compatibility with the dosing agents of the crude oil dehydration system. The experimental protocol and screening process were developed for different agent combinations and dosing concentrations. The experiment results concluded that the optimum retention time frame is 15 minutes for all three organic flotation agents. The performance indexes of effluent outflow can be achieved at suitable dosing level. With the increase of dosing level, the flocculation particles changed from small to big, and the state gradually changed from loose suspension to dense flotation, which tends to stabilize when optimum dosage is reached. The compound organic agents which include B (B1+B2) and C (C1+C2) are compatible with the dehydrating agents of common heavy oil, high pour-point oil and thin oil. Organic flotation agent C (C1+C2) has the lowest capital cost in processing waste-water from common heavy oil, high pour-point oil and thin oil, taking into account the overall cost of the agent and the scum treatment. The experiment results presented in this paper provide a useful reference for the screening of organic flotation agents.