The styrene plant has started operation!

　(1) Analysis of hazards associated with startup and shutdown, as well as preventive measures 　　1. Analysis of hazards during the startup of styrene plants and corresponding preventive measures 　　Starting up a plant after maintenance is one of the most important aspects of safe production. During the commissioning of the plant, overpressure, overheating, material leaks, as well as various equipment and mechanical failures can easily lead to various safety accidents. Therefore, special attention must be paid to safety during startup after maintenance. The safety requirements for starting up the styrene plant are as follows: (1) After maintenance on the styrene plant, the maintenance team shall hand over responsibility to the production workshop. The construction site must be left in order after work is completed, with all materials removed and the area cleaned. Toxic and harmful waste metals, equipment, and pipelines must be handled safely by designated personnel to prevent future problems. The equipment and pipelines after maintenance must be thoroughly cleaned; they can be sealed only after careful inspection, with inspection records and signatures from the maintenance personnel provided. 　　(2) The production supervisor in the workshop shall organize a comprehensive inspection in accordance with the startup plan to prepare for the system startup. And maintain close contact with the plant dispatcher for unified command, starting the units in sequence. The maintenance and construction unit shall organize personnel responsible for ensuring service continuity, tasked with monitoring and carrying out emergency repairs. 　　(3) Before starting the vehicle, conduct a thorough inspection of all safety facilities such as ventilation, communication systems, fire suppression equipment, ladders, platform railings, and lighting to ensure they are in good condition. Pay special attention to flammable materials like wooden planks left on high-temperature equipment and pipelines; these must be removed to prevent fires caused by high temperatures. 　　(4) Before starting up the plant, it is necessary to modify the control parameters and operating procedures in a timely manner according to any changes in processes, equipment, instruments, and electrical systems. The workers on duty must be informed and trained so that they become familiar with the new parameters and operating procedures. 　　(5) Pressure vessels, storage tanks, and pipelines that have been overhauled must undergo pressure testing, leak testing, and airtightness tests as specified. Transmission equipment must be tested individually, and safety valves and explosion-proof membranes must be properly adjusted and reset ； The instruments (including control valves) and interlocks that have been overhauled must be recalibrated and tested to ensure they are functioning properly. 　　(6) For closed equipment and pipelines that receive flammable and explosive materials, gas displacement must be carried out in accordance with the process requirements before the materials are introduced, ensuring that the oxygen content is below 0.3%. The blind plates must then be removed step by step as specified in the flowchart for removing blind plates, and verification checks must be conducted after completion. 　　(7) Feeding must be carried out slowly; after increasing the amount, it is necessary to monitor changes in process parameters. Only once everything is stable should the amount be increased again. 　　(8) The temperature increase should also be carried out gradually; the rate of temperature increase for the hydrocarbonation/dehydrocarbonation reactions should not exceed 30°C/h, and the rate of temperature increase in each column should not exceed 10°C/h ； The temperature rise rate in the first stage of the dehydrogenation reactor/302 shall not exceed 10°C/h. 　　(9) The system’s voltage rise and fall speed should be slow. 　　(10) While driving, pay attention to checking and monitoring the on-site equipment, with special focus on the hydrocarbonation/dehydrocarbonation reactor and dehydrogenation reactor systems; any abnormalities should be reported promptly for proper handling. 　　2. Analysis of hazard factors during the shutdown of styrene plants and preventive measures The shutdown of such plants is an important aspect of safe production. During the shutdown of the plant, overpressure, overheating, material leakage, pump cavitation, and tank roof collapse can occur easily. During periods of plant shutdown, serious accidents occur frequently. Furthermore, the shutdown of the plant is intended to prepare for its major maintenance. If the safety requirements are not met, it will inevitably affect the safety of the maintenance work and even pose risks to it; therefore, the shutdown must be carried out safely and smoothly to create conditions for safe maintenance. 　　During the shutdown of the styrene plant, in addition to the regular tasks, coking of the dehydrogenation catalyst as well as cleaning and steaming of ethylbenzene in tower DA-401—the ethylbenzene/styrene separation tower—and in the styrene distillation tower are required. To ensure the safety of shutting down the plant, in addition to following the operating procedures and shutdown plans strictly, the safety requirements for shutting down the styrene plant are as follows: (1) The shutdown of the styrene plant shall be uniformly directed by the production scheduler and the workshop supervisor in accordance with the shutdown plan, to ensure a safe shutdown. 　　(2) When the alkylation/alkyl transfer reactors DR—101A/B and the alkyll transfer reactor are shut down, the pressure drop rate of the system must not exceed 0.1 MPa/h. 　　(3) The cooling rate of the steam superheater BA—301 shall not exceed 60°C/h, and the pressure change rate in the dehydrogenation system shall not exceed 0.1 MPa/h. 　　(4) The cooling rate when each tower is shut down shall not exceed 10°C/h. 　　(5) When the dehydrogenation reaction system chokes, the temperature rise rate of the system shall not exceed 30°C/h. During the burning process, if the temperature at any point in the catalyst bed exceeds 500°C, the amount of air supplied should be reduced accordingly to keep the temperature below 500°C. 　　(6) During shutdown, empty the tower using a pump; someone should monitor the liquid level in the tank. Once the level reaches zero, the pump must be stopped immediately to prevent it from running dry or leaking. 　　(7) After the unit is shut down, the materials flowing in and out of the unit shall be cut off in accordance with the shutdown plan and process requirements, and all such materials shall be removed from the unit area as per relevant regulations. Flammable, explosive, toxic, and corrosive materials are recovered or vented through flares. Flammable and explosive gases under pressure without flare facilities should be released slowly, with gradual pressure reduction ； Fire protection measures must be taken at the end of the vent pipeline. 　　(8) Equipment, containers, and pipelines containing toxic, flammable, or corrosive materials shall be thoroughly cleaned using steam purging, hot water boiling, alkaline neutralization, and nitrogen purging as specified, to ensure that no oil or air remains inside them. Sampling and analysis shall meet the safety technical requirements. After the analysis is successful, a blind flange that meets the requirements of the process pressure rating is added to isolate it from the connected equipment and pipeline systems. 　　(9) Designate a specific person to apply blind flanges in accordance with the blind flange diagram specified in the parking plan; the blind flanges must be numbered uniformly, and their markings must be clear, in order to prevent leaks. 　　(10) When parking, for equipment such as tanks, vats, towers, and pipelines that still contain flammable, explosive, toxic, or corrosive materials, warning signs stating “Materials present; be careful of fire or isolate” should be placed on the outlet openings or at the connections to the equipment system, and a dedicated person should be assigned to supervise them. 　　(II) Analysis of hazard factors in normal production and preventive measures Based on the analysis of the hazard factors present during the production process in oxidation reactors, operational hazards also exist in actual production operations. 　　1. The reason for the high levels of superoxide in the exhaust gas from the SMART ethylbenzene oxidation dehydrogenation reactor is: (1) During startup/shutdown and load changes, the feed rate of the ethylbenzene mixture and the oxygen feed rate are not matched ； 　　(2) During normal production, the ethylbenzene feed pump suddenly failed and stopped operating ； 　　(3) Later stages of use of oxidation catalysts and dehydrogenation catalysts ； 　　(4) The water ratio in the ethylbenzene mixture is too low ； 　　(5) The pressure of compressed oxygen rises suddenly, while the feed rate of the ethylbenzene mixture remains unchanged. 　　2. Factors causing overheating and runaway temperature in the reactor 　　(1) The flow rate of dilution steam is controlled too low, or even set to zero ； 　　(2) The pressure of compressed oxygen rises suddenly, while the feed rate of ethylbenzene and other compounds remains unchanged ； 　　(3) Compressor failure ； 　　(4) The positive pressure feeding time during the first start-up is too long ； 　　(5) Sudden reactor leakage.

Thank you so much! Are there any special plans or protective measures for starting up, shutting down, and maintaining the inhibitor system?