Breakage of the pre-lift steam pipe in the catalytic cracking riser
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We have two sets of catalytic cracking units: one is of the coaxial type and the other is of the parallel high-low type. The riser sections of both were modified to use the patents from Luoyang Petrochemical Research Institute, and the Y-shaped section includes a horizontal portion. The lift steam and the lift dry gas are mixed together in a lift pipe. But this time, both of them broke during the maintenance – please help analyze the reasons.
The approach is sound; it’s the details that determine success or failure.
It is estimated that it is the low temperature of water vapor and dry gas, combined with a high catalyst temperature, that causes large stress variations in the pipes, leading to their rupture; I wonder if there are any other reasons as well?
Has it been checked to find out what caused the break? Whether it is caused by wear, corrosion, thermal stress, or other factors, the characteristics of the fracture surface should differ depending on the cause.
We also underwent modifications as part of the pre-upgrade in 06; I’m not sure if that connection was severed as well We’ll talk about it when it’s time for maintenance.
1 Material issue with the fractured lift pipe. 2 The quality of the raw materials is poor. 3 The feeding atomization effect is poor, with deviation in flow. 4. The number of reaction cut feedings is high.
We also want to adopt this type of pre-lifting. We would like to ask those who have already carried out technical upgrades upstairs: to what extent does it help improve liquid yield and address the problem of coking in the lift pipe? This post was last edited by netuser on 2009-2-4 22:50]
Catalyst erosion, steam thermal shock; corrosion can occur when dry gas is used
Could the original poster draw a schematic showing the mixing location, the path and angle of the pipelines, the location of the break, and are there any photos of the broken area? Improper stress design, low-quality materials, and catalyst wear are all possible factors; analysis should be conducted in conjunction with on-site photos.