What are the start-up and heating steps for an external coil reactor?

The start-up and heating of an external coil reactor must follow a strict temperature gradient control procedure to prevent thermal stress damage and equipment failure. In the initial stage, the circulating pump must be started to fill the coil system with heat transfer medium, and the vent valve should be opened to remove gas from the coils, ensuring unobstructed medium flow. During the low-temperature preheating stage, the temperature should be increased to 80-100℃ at a rate not exceeding 25℃/h, and maintained at this temperature for 1-2 hours to ensure uniform heating. During this stage, the temperature difference between the coils and the reactor body must be closely monitored and controlled within 30℃. In the intermediate-temperature stage, the temperature is gradually increased to 50% of the process temperature, and the heating rate can be increased to 40℃/h, but the stirring speed must be adjusted simultaneously to promote convective heat transfer of the material inside the reactor.

When the process temperature is reached to within 50℃, the fine temperature control stage begins, reducing the heating rate to 10-15℃/h, and the PID controller is activated to automatically adjust the heat transfer medium flow. After the temperature stabilizes, a hot tightening operation is required to re-tighten the flange bolts to compensate for the decrease in sealing pressure caused by thermal expansion. Throughout the entire process, the temperature difference between the inlet and outlet of the coil must be monitored in real time. Under normal operating conditions, the temperature difference should be maintained within the range of 10-20℃. An excessively large temperature difference may indicate insufficient medium flow or scaling. The emergency cooling system must be kept on standby and able to immediately inject cooling medium in case of overheating. Temperature record curves must be completely saved as a basis for assessing the health status of the equipment.