An anomaly during the oil priming phase before operation

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The conversion of the diesel hydrogenation unit into a system for priming oil during the start-up of the heat high and low fractionation units involved initially establishing the reaction cycle and the distillation cycle separately; however, to accelerate start-up, both systems were primed with oil at 200°C, thereby reducing the time required for product adjustment. However, during operation, due to insufficient preparation of the liquid levels in the two systems involved, no liquid level was detected in the hot high-pressure tank even 30 minutes after oil intake began, and still no liquid level was observed after 45 minutes. Investigations were carried out throughout this period, and it was found that the liquid level in the hot high-pressure tank was inaccurate; once it reached its capacity, the oil flowed into the cold high-pressure tank. By the time a liquid level appeared in the cold high-pressure tank, the hot high-pressure tank had already been full. No liquid level is visible in the circulating hydrogen separation tank. Fortunately, the reactor outlet temperature was not high during startup, so no serious consequences occurred. Conclusion: The start-up process should be carried out step by step, without making arbitrary decisions on a whim. In particular, changes in processes and steps can easily lead to accidents due to staff unfamiliarity.