Abnormal fluctuations in reboiler steam flow and sensitive plate temperature
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The bottom reboiler of the distillation tower uses steam at 2.2 MPa, while the side-line reboilers use saturated steam at 0.45 MPa; under normal conditions, the consumption of each type of steam is around 6 t/h. The steam condensate from the two horizontal thermosyphon reboilers flows into the condensate tank and is then discharged via control valves. Currently, the steam flow rate to the side-line reboiler and the liquid level in the condensate tank experience sudden and significant fluctuations. Meanwhile, fluctuations in the temperature of the stream exiting the reboiler cause variations in the overall tower pressure and bottom temperature; in severe cases, the condensate tank becomes full instantly, and the steam flow rate drops to zero right away. I wonder which sea traveler has encountered such a situation? It has been determined that there is a slight leak in the tube bundle of the side-reboiler; the light components inside the tower are isobutane along with a small amount of n-butane. The tower pressure is higher than that of the condensate tank, and it is not clear whether this is related to the leak.
I assume the tank is positioned below the reboiler, with the condensate flowing into the tank by gravity. The force driving the discharge of condensate is the pressure in the gas phase space of the condensate tank; when this pressure decreases, it becomes difficult to discharge the liquid even if the LV is fully open, and in some cases the condensate may even flow back into the tank through the piping system. Behind the FV, there should be a balance tube connected to the gas space of the condensate line to establish pressure. A pressure of 2.2M is high enough, even if it is slightly subcooled. The saturated vapor pressure inside the tank is also high enough to allow it to return. It’s hard to say about low-pressure steam.
This post was last edited by HEJIYUER on 2021-2-19 at 23:38. I assume the tank is located below the reboiler, and the condensate flows into the tank due to gravity. The force driving the discharge of condensate is the pressure in the gas phase space of the condensate tank; when this pressure decreases, it becomes difficult to discharge the liquid even if the LV is fully open, and in some cases the condensate may even flow back into the tank through the piping system. Behind the FV, there should be a balance pipe connected to the gas space of the condensate tank to establish pressure. A pressure of 2.2M is high enough, even if it is slightly subcooled. The saturated vapor pressure inside the tank is also high enough to allow it to return. It’s hard to say about low-pressure steam.
Since a leak has been detected, the heat exchanger must be replaced first. How did you determine the minor leak?