No.3 unit in polypropylene workshop of Maoming Petrochemical Company was cut into a formal silo to produce S1113 material, and the product index was qualified. The maintenance task was completed two days ahead of schedule, and the start-up was successful. It is reported that the plant was successfully started ahead of schedule, with an output of 1,511 tons more than originally planned, which not only greatly eased the pressure on the propylene tank position of the company, but also created nearly 2 million yuan for the company.

this overhaul involves a lot of complicated work and extensive field work. The overhaul includes many important overhaul tasks such as cleaning the first reactor, replacing the quench liquid nozzle, replacing the thermowell in the first zone, handling the second reaction block, and replacing the screw shaft sleeve of the extruder. The polypropylene workshop started the maintenance plan in advance, cooperated with the electromechanical instrument and other units efficiently, made the maintenance task list, prepared the technical transformation of the project, and collected materials, so as to realize the scientific and overall management of various maintenance work. The process, equipment and safety management team of polypropylene workshop started from overall planning, construction design, safety guarantee and other aspects, and strictly implemented the maintenance management regulations of the company and its divisions.

since the shutdown of the plant, the workshop has strengthened the safety and environmental protection management in the shutdown process, strictly controlled all kinds of emission indicators, ensured that the pipeline surplus of No.3 plant was recovered by 111%, and realized "zero emission" shutdown. In the maintenance work, strictly implement the requirements of environmental protection, so as to achieve "no gas, no dust, no oil pollution". At the stage of unit shutdown and purging, polypropylene workshop made a detailed "Three Wastes" emission plan based on the principle of "zero pollution" before the shutdown of Unit 3, conducted many discussions and desktop deduction, and distributed the plan to the team in advance, so that all staff could learn the risk assessment content of each operation from multiple angles and in all directions. Implement "all-weather and 24-hour" monitoring at the purging site, pay close attention to equipment leakage points and low-point discharge points, and recycle oil, waste water and waste materials at designated points to ensure a clean maintenance environment without dead ends.

It is reported that the replacement of the filter element of the bag filter S311 is a difficult point in this clean and green overhaul operation. There are a large number of filter elements in S311, and the concentration of triethylaluminum residue in the fine powder adhered inside the filter element is high, which makes it difficult to deactivate. In the process of replacing the filter element in the past, when the S311 head cover is opened and exposed to air, there will always be different degrees of smoke, which is a bottleneck problem in the safety and environmental protection maintenance work. The residual triethylaluminum in the system is flammable and explosive, and whether its inactivation effect is complete is the guarantee of maintenance safety. Before stopping, focusing on the key operation points such as replacement, deactivation and safe delivery of unit 311, the polypropylene workshop actively carried out technical research, conducted special analysis and discussion for many times, and optimized the S311 maintenance process treatment scheme. In addition to the conventional CO2 deactivation treatment, 4.5% O2/N2 deactivation, factory air mixed nitrogen purging and other treatment steps were carried out in turn, and the on-site construction operation could only be carried out after the temperature change and on-site exhaust conditions confirmed that it was completely deactivated. This operation adopts the gradual method of triple gas deactivation. During deactivation, the amount of carbon dioxide, oxygen and nitrogen is constantly adjusted according to the temperature change, and the rising range of temperature and pressure in the tank is closely monitored, and no smoke is generated in the whole process. Innovative thinking in the workshop, the smoke-free deactivation of 3# device was realized for the first time, which provided an effective guarantee for safe and green maintenance.

during the maintenance, the workshop strictly implements the HSE management principles centering on "risk management and control", insists on "safety propaganda" and "safety disclosure" before operation, pays special attention to all operation links, keeps all operation links under control at all times, and effectively avoids accidents such as leakage, material cross-linking, overtemperature and overpressure. They strengthened the safety supervision of operation links, took "zero tolerance, zero violation" as the criterion, strengthened the overall planning of maintenance projects, made targeted preventive measures through comprehensive JSA safety analysis, controlled operation risks in advance, and built a safety wall. In addition, the workshop management personnel must go to the site to implement various safety measures before the operation, adopt irregular inspection methods, immediately investigate and reform the illegal behavior of the operation, conduct high-pressure situation management on the supervision of the direct operation link, strictly control the "low old and bad" behavior in the operation process, ensure the safety control of the whole operation process, and achieve high-standard and high-quality maintenance results of "stable stop, good repair and smooth start".