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This post was last edited by Tianyi on 2015-4-20 at 19:16. The impact of lightning on the plant: The moving equipment in the Unipol polyethylene plant includes the recycle gas compressor (K24003), temperature control water pumps (G24004/4005), catalyst feeders (V24036/4037), triethylaluminum pumps (G21503/1504), nitrogen compressors (K21102/1103), off-gas compressors (K25206/5207), the chiller system (X25214), and the granulation system (Y27001), among others. The occurrence of voltage fluctuations often leads to the shutdown of some or even all of the above-mentioned mechanical equipment. The shutdown of K24003 and/or G24004/4005 can cause serious damage to the production facility, while the short-term shutdown of other mechanical devices results in the shutdown of individual systems, increasing material and energy consumption; however, the impact on the facility is relatively much less severe. 2.1 If power fluctuations cause K24003 and G24004/4005 to stop operating, it will have a fatal impact on the plant, especially during periods of high production load. This situation can lead to caking inside the reactor, as well as blockages in the reactor’s distribution plates and the pipes associated with E24002, thereby affecting the plant’s operational cycle or causing blockages in the discharge system. In severe cases, large clumps form inside the reactor, forcing a shutdown of the reactor for cleaning. The average shutdown time to open the reactor in Unipol’s polyethylene plant is over 50 hours. 2.2 When K24003 stops due to voltage fluctuations, G24004/4005 do not stop; the impact on the reactor is similar to that described in 2.1, but it helps to reduce blockages in E24002. 2. 3 G24004/4005 shutdown: If the power fluctuations do not cause K24003 to shut down, then the impact on the equipment is relatively minor. However, the shutdown of G24004/4005 will lead to a sharp rise in the reactor temperature; if this is not addressed promptly, clumping or even violent reactions may occur inside the reactor. 3 Handling after a power fluctuation: If a power fluctuation causes K24003 and/or G24004/4005 to stop operating, it is necessary to follow the principle of prioritizing the operation of the equipment over that of the reactor, to carry out rapid procedural actions, and to restart K24003 and G24004/4005 as soon as possible. 3.1 After K24003 stops, a delay of 10 seconds occurs; regardless of whether G24004/4005 stop or not, Type II termination should be triggered automatically. HV258 should be turned off automatically, HV260 should be turned on, and CO should be injected into the reactor automatically. Additionally, the spare CO cylinder should be opened to supply more CO to the reactor. If Type II termination is not triggered automatically, HV258 should be manually shut down promptly, HV260 or HV264 should be opened, and 2–3 bottles of CO should be quickly injected into the reactor manually. Once the reactor has been depressurized, K24003 and G24004/4005 should be started immediately, after which appropriate process adjustments should be made based on the reactor’s operating conditions. 3.2 G24004/4005 stops; after a power fluctuation, K24003 does not stop. The stopping of G24004/4005 causes the reaction temperature (TIC226) to rise rapidly. When the actual temperature exceeds the set point by 7 ℃, Type I termination should be triggered automatically, with CO being injected into the reactor. If Type I termination is not triggered automatically, it should be triggered manually or CO should be injected manually. 4 Measures to reduce the hazards caused by surge voltage: (1) Increasing the memory time for K24003’s shutdown due to surge voltage can **reduce the likelihood of such shutdowns; this measure needs to be carefully evaluated for different compressors. (2) G24004/4005 can be set to start automatically. (3) Check each time the machine is stopped to ensure that the automatic switching and self-starting functions of the K24003 lubrication oil pump are working properly. (4) Ensure that the logic for Type I and Type II termination, as well as the 4 programmable valves of the termination system, are in good standby condition. (5) After a power fluctuation causes K24003 and/or G24004/4005 to stop, CO should be injected into the reactor promptly, and K24003 and G24004/4005 should be restarted as soon as possible. (6) The shutdown alarm settings for key devices such as K24003, G24004/4005 have special sounds. (7) A special audible alarm is set for the rising rate of the reactor temperature. 5 Conclusion (1) The K24003 unit at the Central Plains polyethylene plant was manufactured by Italian company Pignone; its memory time has been increased from 0.5 s to 0.8 s. Since its operation began in 1996, there have been 13 instances of power fluctuations, and after the memory time was increased, such fluctuations have not caused the K24003 unit to stop operating. (2) The self-start-up operation after shock stop for G24004/4005 is currently in progress. (3) At present, the most economical and effective measure to increase the production capacity of similar devices worldwide is to implement condensation operations, which can boost production capacity by 30% to 200%. Operating at such high loads, if disruptions such as power fluctuations cause K24003 and G24004/4005 to stop functioning, it can cause even greater damage to the devices. Therefore, it is urgent for all such devices to take effective measures to minimize the impact of power fluctuations. The measures mentioned above are for reference only.