External heat gas return line issue
Thread Content
Due to frequent leakage issues at the wall valve flanges and the wall welds of our external heat extraction gas return line, we simply stopped using that line! Is your gas return line in use? And what impact does disabling the gas return line have on heat extraction from outside? (During the shutdown in the previous cycle, it was found that there was extensive lining detachment and cracking at the external heat extraction discharge port; it is not clear whether this is related to the shutdown of the gas return line.) I hope the experts can provide some guidance. Thank you!
How did you deactivate it? Was it cut off during maintenance? There are usually no valves for this
In the gas return line, due to the relatively high flow rate (and the fact that such lines are generally not very thick), catalyst particles are present within it, which causes wear on the pipeline
The last edit to this post was made by Refiner on 2017-11-2 at 10:48. Here, there is no gas return line for external heat extraction; however, it is present in the premixing section of the second catalytic riser
Teacher: There are wall valves that should be turned off during operation! What are the advantages and disadvantages of disabling the gas return line?
The previous gas return lines were lined inside, but the newly installed chromium-molybdenum pipelines do not have a lining
Teacher: In what form is heat extracted externally?
Don’t yours have a lining? If not, they wear out very quickly
Is the return phase of this flue gas return line a dense phase or a dilute phase?
Currently, most external extraction systems are of the downflow type; therefore, a gas return line must be installed. If you shut it off, it will definitely affect the operation of the external extraction system! The catalyst slurry flows downward to the lower part, where fluidizing air is used to keep it in a fluidized state. This gas phase needs an outlet; otherwise, it’s like trying to pour cola from a bottle in an upright position – gas buildup will occur, and this will have a negative impact on the equipment Therefore, it is necessary for us operators to find a suitable flow rate of fluidizing air during operation and maintain it at a relatively stable level, so as to ensure a stable operating condition for the external heat exchanger!