Why does the bed temperature in the reduction section of continuous reforming decrease?
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Dear colleagues: Recently, we have been carrying out continuous reformation of the UOP third generation, and the bed temperature in the reduction section has decreased compared to before; it now varies mainly between 380 and 400 degrees. The highest temperature, namely the last temperature point in the reduction stage, fluctuates between 405 and 430 degrees (fortunately it doesn’t drop below 400 degrees, otherwise regeneration would be halted due to heat). And both the amplitude and frequency are greater than before. The inlet temperatures at the beginning of sections 1 and 2 in the reduction section are normal, with no changes. Our workshop suspects that it might be due to changes in the purity of reduced hydrogen, but the test analyses show no significant changes. I would like to ask: 1. What are the reasons that can cause a decrease in the temperature of the reduction section as well as significant fluctuations in it? 2. What range is appropriate for the bed temperature during the reduction stage? What is the minimum level required to ensure a good reduction effect (PS6 catalyst)? 3. What is the best approach to take under current conditions? Please do not provide further advice. Thank you
The reason for this situation could be an excessive circulation rate of the catalyst, or an inappropriate temperature of the reducing hydrogen. It is personally recommended to adjust the temperature of the catalyst in combination with reduced hydrogen to the optimal value.
It is possible that the error of the level gauge in the reduction zone is actually low; personally, I suggest increasing the material level in the reduction zone and raising the flow rate of the reducing gas accordingly. Also, check whether the temperature of the regenerated catalyst and the lift gas is low.
I encountered such a problem with my unit before; it was resolved by increasing the material level in the reduction zone and raising the amount of reduction gas. Another thing to pay attention to is the drying in the regeneration tower; if the flow rate of the drying gas is too low, the catalyst won’t dry properly, and excess moisture will be carried into the reduction section, which may also cause a low temperature in that section. Additionally, it’s necessary to have the instruments checked to ensure that the thermocouples are properly sealed. These are all issues we have encountered and resolved in practice. I hope this information is helpful to you, even though it may not be presented perfectly.
The reduction reaction is related to hydrogen partial pressure, water vapor pressure, temperature, and flow rate; then there’s also the catalyst to consider
1. The catalyst’s heating rate is too high. 2. The electric heater is faulty, resulting in a low temperature of the gas. 3. The reducing gas is too pure. 4. The regenerated catalyst contains excessive moisture! That’s all I know, as my knowledge is limited!
First, increase the flow rate and temperature of the reducing gas; it’s not necessarily 377 and 482 degrees. I encountered this issue once before due to water in the reducing gas; also, consider reducing the catalyst circulation rate – in the past, we saw a significant drop in temperature when it was above 90%. If all the thermocouples show a decrease in temperature, the board or connectors of the thermocouple instrument should be checked, as well as to see if water has entered the thermocouple box