Pre-heating line in front of the smoke extractor inlet gate valve in the heavy oil catalytic unit
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Our company’s 600,000 tons per year heavy oil catalytic unit was designed by the Beijing Institute. A DN50 pre-heating line was installed at the inlet gate valve of the flue gas engine; however, in practice this pipeline often became blocked, preventing normal operation. This year, after the maintenance of the flue gas engine was completed and testing began, the machine suddenly shut down due to instrument-related issues, and the gate valve dropped suddenly. At that moment, the pre-heating line for the flue gas engine was not functional, resulting in an excessive drop in temperature of the flue gas pipes, which stretched the length of those pipes by about 1 meter. In future designs, could the diameter of this pipeline be considered larger? I would appreciate the advice from all experts. Thank you to all the experts.
Hello! As far as I know, the function of this line is to raise the temperature of the pipeline carrying the gate valve fluid; it can be modified to an upward flow configuration. Alternatively, expand the diameter of this pipe by only 100, install it after the pressure-reducing orifice plate, use two valves along with an air vent, for pipeline preheating.
Ours is DN150, and we haven’t encountered this issue in two years. Regarding the DN50 mentioned by the poster, what size is your installation?
Change it to DN150-200 pipelines, and add anti-settling as well
Is our device still 300,000 or 150? Why are you so meticulous?
The pre-heating line in front of the gate valve usually has an upper opening; a size of DN200 or larger is preferable. Whenever the smoke extraction system needs to be repaired urgently, the pre-heating line remains unobstructed
Our unit does not have a pre-heating line, but there is one that leads to the chimney; once the gate valve is closed, this line should remain unobstructed, with a DN50 diameter
Logically, for a catalytic system of 60 tons, the pre-heating line for flue gas is generally designed to be DN250; a pipeline of DN50 is too small, and the catalyst in the flue gas will definitely accumulate there, causing blockages.
We have a model of 150, and we’ve never had such problems; I suggest the original poster consider making some improvements.
It has happened to us before; I believe the reason was the lack of insulation at that time, and after installing insulation, there have been no more blockages. However, DN50 is indeed too small; it is recommended to use DN100 or higher. For reference only.