Problem identification of depropanizer reboiler or condensate pipeline
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Please help with the analysis: The low-pressure steam enters the reboiler T1 after throttling, and the condensate flows into the condensate recovery tank M1 and is discharged into the condensate recovery system through pump P1A/B and valve V1 (linked with the M1 liquid level). For a long time, the full opening of valve V1 was still insufficient and a normally open bypass was required. Therefore, the production comrades believed that the original design of valve V1 was not good and needed to be recalculated and resized. However, after on-site measurement, the temperature of the condensate was about 104 degrees, which was much higher than the normal value. Therefore, it is suspected that the reboiler T1 is partially blocked, resulting in a decrease in heat exchange capacity. I hope some Haichuan friends can help analyze how to support which conjecture is the real problem to be solved. Thanks!
Based on the analysis of the phenomenon you gave, both conjectures are wrong. First, if the heat exchanger capacity is reduced due to partial blockage of the reboiler T1, the temperature of the condensate will not be high. Second, the temperature of the condensate is high, indicating a large temperature difference. The increase in temperature difference is beneficial to heat exchange, but when the conditions on the process side remain unchanged, the amount of condensate will not increase due to high heating temperature, which means that the amount of heat exchange will not increase. If the drain valve remains fully open at this time, it means that the flow rate on the process side is large, and the increase in heat exchange will cause a large amount of condensate. There is no blockage at this time, but it is very smooth. Therefore, the real reason should be that the temperature on the process side is too low, or the components are too light, and the process side takes too much heat, which causes a large increase in heat exchange, so the amount of condensate is large. Treatment method: Reduce backflow.