[Haichuan’s Best Practices] Beihai Refining & Chemicals Achieves Oxygen-Free Coking Removal in Fractionation Towers for the First Time

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Beihai Refining & Chemical completed anaerobic coking removal from the distillation tower for the first time 2019-01-28 Source: Sinopec News Network Recently, the catalytic cracking unit at Beihai Refining & Chemical was shut down for maintenance; given the tight schedule and heavy workload, removing coke from the bottom of the distillation tower posed a significant challenge. As planned, the rectification efforts are primarily focused on emergency repairs to the regenerator and reboiler systems as well as the fractionated slurry system. The distillation tower was only subjected to steam purging, inspection, and maintenance for the heavy oil system; the entire distillation system was not thoroughly drained of oil and purified with steam in accordance with overhaul procedures, nor was the distillation tower subjected to chemical cleaning or passivation. Coking removal in distillation towers poses risks such as spontaneous combustion of ferrous sulfide, asphyxiation by oil and gas, and burns from oil coke. Beihai Refining & Chemical Processing organized repeated discussions and analyses, and selected an anaerobic operation plan from several proposed coking removal schemes. Anaerobic coking cleaning is rarely used in the refining and chemical enterprises of the group company, with Beihai Refining and Chemical being the first to adopt it. The company attaches great importance to this matter, has established a technical team to determine safety measures and construction plans, and has prepared a checklist. Equipment, safety, technical, and process personnel conduct on-site verification of the pipelines and valves to ensure that the processes that need to be isolated are properly isolated, and that the processes that need to remain operational are functioning correctly, thus keeping the risks in the working environment under control. During the coking removal process, company management provided on-site supervision and guidance, coordinating safety measures to ensure that the nitrogen content at the bottom of the distillation tower remained at least 96%. At 11:00 on January 20, specialized workers entered the tower to begin the coking removal operation, which was successfully completed by 16:30 on the 21st. A total of 14 tons of coke were removed, which saved labor costs and gained time; the results exceeded expectations. (Huang Lifeng, Zhang Zhipu)