External heat exchanger issue
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The heat extraction efficiency of the external heat exchanger in our newly installed reheating unit is poor. Some time ago, with the flow rate of the fluidizing air and the lifting air remaining unchanged, the steam production volume suddenly dropped; no matter how we adjusted the air flow, it wasn’t possible to increase it again. The bed temperature is now at 709 degrees. Please advise us on what to do
Actually, there are many possible scenarios for this. Could you please describe the specific details of your device?
Please check whether it is caused by poor water circulation, and what is the water circulation rate?
1. Is the heat extraction mode of your unit upstream or downstream? 2. Observe whether the temperature distribution gradient across the upper, middle, and lower sections of the external heat exchanger is reasonable, in order to determine if there is any localized poor fluidization within the external heat exchanger. 3. Check whether the opening degree of the double-acting slide valve has increased compared to the previous stage; if it has increased, then the possibility of leakage in the tubes of the external heat exchanger cannot be ruled out. 4. Determine whether forced circulation is available for the external heat exchanger; if so, activate it
The most direct approach is to check the inventory of the external heat exchanger; based on the question raised by the poster, it seems that there is a problem with the fluidization in the regenerator. It’s about whether the dense phase in the regenerator is dense or not. This results in insufficient catalyst entering the external heat extraction inlet, with no heat flow in the external heat exchanger, thereby leading to a reduction in heat extraction.
The original poster posted a message and then disappeared; it’s not clear whether the issue was resolved or not. Please show up and share some updates with everyone
Our external heat extraction air volume is 6000, with a range of 8000; there are three temperature settings – high, medium, and low – at values of around 400, over 100, and also over 100 respectively. The inlet temperature is 650. There are two streams of air for fluidization and two streams for lifting, but the heat extraction effect is very poor; the amount of water supplied is only in the teens of tons
1. Check whether the inlet valve for the supply air is unobstructed and whether there are any abnormalities in the entire air duct system. 2. Check the changes in the flow rate of the fluidization air, and determine whether fluidization is inadequate by considering the temperature distribution within the internal fluidization air coils. 3. Compare to determine whether both external heat exchangers exhibit the same phenomenon
Based on the data analysis you mentioned, the external heat extraction system has not achieved fluidization; adjustments are needed to establish catalyst fluidization for external heat extraction. Can I ask you a few questions about data? 1. What is the opening degree of the external heat slide valve? Spool valve pressure drop? Density above the slide valve? 2. What were the main air flow rates before and after this phenomenon occurred, what was the opening degree of the external circulation slide valve, and what were the levels of carbonized material and the secondary storage? I need to have these data to help you analyze it.