How to understand T210?

Thread Content

Rapid adjustment of the circulating hydrogen heat exchange bypass valve (T210) caused leakage at the feed orifice plate flange of furnace F102 (the second circulating hydrogen heater). Day shift, February 22, 1990. Progress: During the midnight shift, hydrogen production could not be maintained due to instrument failures, forcing the plant to shut down at 7 a.m. As instructed by higher authorities, the day shift should bring the plant up to conditions for resuming operation by 14:00. At that time, the inlet temperature of reactor R101 was 291°C, and the inlet temperature of R102 was 289°C. Furnace F101 had 7 burners lit, while furnace F102 had 8 burners lit (the first and second cycle hydrogen heating furnaces). To increase the furnace load and adjust the inlet temperature of the reactor after feeding through the heat exchanger cold bypass, at 13:50, the shift supervisor manually adjusted T210, causing the valve position to increase instantaneously from 30% to 95%. About 4 seconds later, a sound of leakage from the flange could be heard coming from the furnace. Upon reminder from the operator, T210 was immediately adjusted back to its original setting. After that, the leaking sound disappeared. When the valve position changed, the TRC-210 temperature reading dropped instantaneously from 220°C to 75°C, and temperature fluctuations of 15–25°C occurred at the inlets of reactors R101 and R102A respectively, which caused the start-up of oil feeding to be delayed by one and a half hours. Afterward, the conditions for oil inflow were restored: the inlet temperature of R101 was 295°C, and that of R102A was 293°C; however, a slight leakage was still detected at this flange. Reason: 1: Excessive temperature rise due to improper operation caused the material to emerge from the valve gland. 2: Low level of operational skills, blind operation. 3: There is no proper planning in work, and there is a rush to achieve results. 4: Training on relevant process operation knowledge is insufficient. 5: Employees lack safety awareness. Lessons learned: 1: Operations must be carried out strictly in accordance with the procedural guidelines, respecting the regulations regarding temperature changes and load levels. 2: Strengthen training in operational skills. 3: During the production process, it is necessary to carry out pre-adjustments, frequent adjustments, and fine-tuning!