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Issue:ISSN 1006-5539
          CN 51-1183/TE


Your Position :Home->Past Journals Catalog->2020 Vol.6

Analysis on the Rectification of Uneven Liquid Distribution into Two Parallel Secondary Separators
Author of the article:Zhang Hao, Cui Changfu, Zhan Ruilin
Author's Workplace:Weizhou Operation Company, CNOOC(China) Zhanjiang Branch, Zhanjiang, Guangdong, 524057, China
Key Words:Separators uneven liquid distribution; Even control; Uneven liquid level; Liquid level control; Branch line

At one on-site crude oil treatment facilities, the crude oil passes through a primary separator before entering two paralleled secondary separators. Due to the different positions of the two parallel secondary separators with different piping configurations, there is an uneven distribution of liquid entering the two separators. Based on a theoretical analysis of the liquid flow at the inlet and outlet of the separators, the liquid level control strategy and vessel pressure control strategy are reviewed. The process control algorithm was modified following the study: 1. Replace the original single control scheme, with flexible use of servo control and single feedback loop control; 2. Switching between multiple control modes; 3. Optimizing PID parameters. The problem of uneven liquid distribution in two paralleled secondary separators was solved successfully. After one-year field application, the two secondary separators have a stable liquid inflow and the oil-water separation efficiency has improved significantly after modification of the control scheme. The oil content at the water-phase outlet drops from 250 ppm to 120 ppm, and the water content at the oil-phase outlet drops from 20% to 12%. The process system is more stable and the unfavorable influence of upstream flow fluctuation is significantly reduced. The total processing capacity after balancing the liquid distribution is increased by about 1000 m3/d, thereby improves the production efficiency and reduces the production cost.

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