Report on the “9.7 Shutdown Incident” at Northwest Energy Chemical Company

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On September 7, at around 1:40, operators at the gasification plant of Northwest Energy & Chemical Company noticed that the flow rate at the outlet of the high-pressure coal slurry pump in Unit 1 was fluctuating repeatedly. By 1:44, these fluctuations intensified; there was no flow at the pump’s outlet and the oxygen-to-coal ratio was high. To ensure the safe operation of the facility, Unit 1 was shut down urgently. From 6:00 to 9:00 on the morning of September 8, the inlet pipeline of the high-pressure coal slurry pump in Unit 2 also experienced blockages, resulting in repeated fluctuations in the pump’s outlet flow rate. By 9:30, the fluctuations became more severe and again there was no flow at the outlet. To ensure system safety, Unit 2 was shut down urgently, followed by the shutdown of other systems as well. The accident lasted from 01:44 a.m. on September 7 until 16:00 p.m. on September 10, when Unit 2 and Unit 1 gasifiers were restarted; pure methanol was produced at 09:24 a.m. on September 10. The accident disrupted normal production for approximately 80 hours. On September 11, the Group Company’s Safety Supervision Department and the Chemical Industry Department initiated an investigation into the \"Northwest Energy Chemicals 9.7 shutdown accident.\" After three days of investigation, it was determined that this was a level-2 accident without any casualties. The direct economic losses, such as the costs for repairing and replacing the reducer of the large coal slurry tank mixer, amount to approximately 100,000 yuan ； It affects the production of pure methanol by 3,500 tons, resulting in indirect losses of around 1.4 million yuan. This was an accident that could have been avoided. The day before the incident, the mixer in the large coal slurry tank was out of service for over 8 hours, and the on-site inspector carried out patrols without actually conducting any inspections ； The DCS trend charts clearly show abnormal current values of the mixer in the large coal slurry tank, yet the control room operators recorded these values without reporting them… The equipment continued to operate despite being faulty, with dangerous signals being issued over and over again, yet no opportunity was seized to prevent accidents from occurring. All assumptions are merely that – assumptions. An accident that shouldn’t have happened did occur, leaving many things worth reflecting on. Equipment inspections: Inspections are carried out in a perfunctory manner. According to the report issued by the accident investigation team of the group company, at 17:45 on the day before the incident (September 6), the mixer in the large coal slurry tank in the gasification workshop of Northwest Energy Chemicals had broken off, and the motor was actually running idle. At 19:54, condensation began to occur at the bottom of Tank 1 for high-pressure coal slurry… It was not until around 00:56 on September 7 that the gasification operators, while conducting inspections of the large coal slurry tank, noticed fractures in the bolt holes of the base plate of the reducer; they immediately contacted the shift supervisor to shut down the mixer. During the emergency repair, the outlet flow rate of the high-pressure coal slurry pump in Gasifier No. 1 fluctuated repeatedly. Fluctuations intensified at 1:44. To ensure the safety of the equipment, an emergency shutdown was immediately implemented for #1 gasifier. By now, 8 hours have passed. Regrettably, during this period, although various signs indicated that the mixer reducer was actually no longer functioning properly (and had stopped mixing), no one detected any abnormalities despite 8 inspections, thereby missing the optimal time for maintenance. It is worth noting that, based on the damage observed on the equipment inspected by the post-investigation team, there was an old crack in one of the anchor bolts of the mixer’s reduction gearbox, and the bolts showed signs of being loose... This indicates that the equipment had been operating with defects for a long time. All of this points to gaps in on-site inspections and equipment management. It is understood that, due to the special nature of their industry, chemical enterprises have certain differences in equipment management compared to ordinary enterprises. Its equipment is characterized by large size, high value, and difficulty in management; therefore, it is necessary to establish a dedicated team for management, maintenance, and upkeep, along with comprehensive maintenance standards. According to authoritative data, 70% of equipment failures are attributed to poor maintenance of the equipment, which is mainly reflected in routine and minor tasks such as failing to lubricate the equipment regularly, not removing dust in a timely manner, and failing to address minor defects in the equipment promptly. The basic aspects of equipment maintenance generally include daily maintenance, regular maintenance, periodic inspections, and accuracy checks. However, a review of the on-site inspection system and equipment management regulations reveals that there is almost no content related to mixer management. The equipment managers failed to implement the inspection system properly; their superficial inspections, coupled with blind spots in the monitoring coverage of the mixer units, turned these areas into gaps in equipment management, creating potential risks that led to accidents. Fortunately, since the mixer in the large-scale coal slurry tank is imported equipment from the United States and is a device that operates for long periods of time, Northwest Energy Chemical Company purchased spare parts in advance, which provided valuable time for the emergency repair of the device. Otherwise, just the process of acquiring new equipment alone will take half a year, and in a market where methanol prices remain high, the financial losses for enterprises will be immeasurable. Data reporting: Data was copied but not reported. By reviewing the control room reports, it is clear that at 17:45 on September 6th, the current value of the mixer in the large coal slurry tank in the gasification workshop dropped from the normal level of 78A to 45A. At 19:54, the current of the 1# high-pressure coal slurry pump also experienced a significant short-term fluctuation... The handwriting was neat and the records were clear... Unfortunately, the control room operators turned a blind eye and failed to report it for further action; this was the last chance to prevent this accident, and we failed to seize it. But why didn’t the operator report it immediately? Why didn’t the on-duty management staff detect the anomaly in the reports and take appropriate action? Do the subsequent handover personnel also choose to ignore it? Why do the operators in the control room turn a blind eye to abnormal process parameters shown on the DCS trend charts? Further investigation revealed that the operator on duty was a new employee who lacked the necessary technical knowledge and had not received any pre-job training; he merely copied the data mechanically, without understanding abnormal changes in the data or knowing how to report them. In fact, according to the \"Northwest Energy and Chemical Safety Education and Training Management System,\" new employees must complete three levels of safety training (i.e., plant-level safety training → workshop-level safety training → team-level safety training), and only after passing the examinations can they start working officially. The team safety training specifies that new employees must be familiar with the safety conditions of their team (position) in terms of production, the safety operating procedures for their position, the performance of the production equipment involved in their tasks, the precautions for maintenance, as well as the correct ways to use such equipment. System documents are left untouched, while implementation is compromised, which inevitably leads to reduced safety outcomes and leaves safety hazards behind. On the other hand, the shift supervisors, those responsible for shift handovers, and the key operators failed to maintain the patience required for their work due to a mindset of \"being accustomed to doing this, being accustomed to seeing it, and being accustomed to *this\". They lacked a sense of responsibility and proper oversight; they turned a blind eye to abnormal data and failed to report or address it, allowing potential problems to develop and spread. Accountability for accidents: a constant reminder. According to the well-known DuPont theory, all safety accidents can be prevented, and all potential hazards can be controlled. According to incomplete statistics, since Northwest Energy Chemical began operating its production facilities, unplanned shutdowns caused by equipment failures have accounted for over 70% of such incidents. The reasons cited in the reports on these incidents are almost always the same: insufficient skill levels among operators, inadequate management and maintenance of equipment, and poor implementation of inspection procedures, among others. Looking at this parking accident, it is striking that all three safety safeguards – equipment inspections, chemical process inspections, and central control – failed one after another; the reasons behind this are worth careful consideration. “‘\"People, machines, materials, methods, and environment\" are the six key elements of modern enterprise management, among which \"people\" is the most crucial element among these. ‘The ’9·7 unplanned shutdown incident’ profoundly exposed the lack of responsibility on the part of a few managers and operators, as well as issues with poor corporate management. It has been preliminarily determined that this is a level-2 non-personal liability accident; accountability must be enforced to ensure that job responsibilities are fulfilled, and such accidents must be prevented from occurring again. ”The staff of the investigation team said.