What are the solutions to the high COD level in the hot water system of catalytic cracking units?
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Recently, this device inspected the hot water system and took samples for analysis from all the heat exchangers through which the hot water passed (all at the outlet of the heat exchangers). The test results showed that the COD value of the hot water at the outlets of the heat exchangers and at the sampling points was around 13–15 mg/L in almost all cases. Yesterday, a water sample was collected; it was a transparent liquid with a faint yellow color, and it felt smooth when applied to the hand. I’m not sure what the quality of hot water is like in everyone’s devices.
What medium is used for heat exchange with your hot water? A high COD value indicates that oil has leaked into the hot water; check the system, remove the faulty heat exchanger, and replace the hot water
We are currently conducting investigations, but it seems a bit impractical to remove the heat exchangers for processing. The results obtained from sampling and analysis behind each heat exchanger so far are also not satisfactory
Looking for heat exchangers whose working fluid pressure is higher than that of hot water – there aren’t many of such devices, I guess
Special attention must be paid to the hot water system; it is a closed system, and it’s difficult to detect problems once they occur. Once an issue arises, the heat exchangers in the entire hot water system will be damaged.
Check the hot water and top circulation heat exchanger.
I’m not sure which has a higher pressure, your hot water or the oil used in the top circulation system. Here, we use variable-frequency pumps for the oil in the top circulation system, and its pressure is much lower than that of the hot water; in the event of a leak, it’s the hot water that leaks into the oil system