Issues with heating up during the catalytic start-up of heavy oil
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In heavy oil catalytic cracking, after the routine maintenance (during which part of the lining was repaired) was completed and heating up of the two reactors started, we filled the external heat-extraction steam drum with water at the appropriate time, and we also introduced steam for protection into the medium-pressure steam network (for both internal and external heat extraction). In our plant, we filled the steam drum with water and activated steam protection for the medium-pressure system once the temperature of the two reactors reached 150°C. How is it done in your plant? . Since part of the lining has been repaired, is it necessary to bake the lining according to the heating curve? (Which teacher can draw a rough temperature rise curve for the two devices?), and what are the things to keep in mind during the temperature rise process of these two devices? I hope to get some guidance from all the teachers. Thank you!
We only started using external boilers after operations resumed normally
It is essential to maintain the liquid level in the drum; the internal heating coil should not reach temperatures above 400 degrees. Steam can be used as a backup protection mechanism to prevent damage to the furnace tubes caused by dry burning. Which lining needs to be replaced? The heating curves are different; for large-scale replacements, it is advisable to consult the design institute.
Lining near the discharge port of the triple cone
The three-choice lining allows for a slower temperature increase when the smoke extractor is turned on, maintaining a constant temperature
The three-choice lining allows for a slower temperature increase when the smoke extractor is turned on, maintaining a constant temperature
Starting early has its advantages; when things get busy, one can ignore it. The heating curve is roughly as follows: maintain a temperature of 150 degrees for 24 hours, then raise the temperature to 350 degrees at a rate of 15 to 20 degrees per hour; keep this temperature for 24 to 36 hours. After that, increase the temperature to 500 degrees at a rate of 20 to 25 degrees per hour, and maintaining this temperature for 24 hours should be sufficient
The temperature for heating should be set according to the specific circumstances! Here, water is introduced as soon as the external extraction process starts; steam is fed into the boiler for protection, and all the steam valves are opened. During the entire startup process, it’s sufficient to maintain an appropriate level of liquid in the boiler. There’s no need to worry about merging the steam with the system at that point. Since the boiler pressure is higher than the system pressure, the steam will naturally merge with the system, thereby avoiding water hammer issues that can arise from improper merging
Water is supplied to the steam drum at 100°C, and the two vessels have constant-temperature linings at 150°C to remove surface water. Steam protection is applied to the medium-pressure steam pipeline network at 250–280°C. The 315°C lining of the two devices loses its crystalline water. Use hot steam for air protection within the range of 350–400°C. (Internal heat extraction is used only for superheating steam; no drum is involved.) The linings of the two vessels are sintered at 500°C. Make sure to activate backflow air or steam at each loose connection. Cooling steam is used for sliding valve purging at 400°C.
(Internal heat extraction is used only for superheating steam; no drum is involved.) Is it not necessary to establish a flow path for the medium-pressure system in the reverse regeneration system?