The relationship between the blending of vacuum residue and regenerator bleedoff
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The unit has experienced three incidents of agent leakage from the regenerator, all of which occurred as a result of an increase in the amount of slag added – initially it was oil from the bottom of the flash tower, and later it was vacuum residue. The symptom was a decrease in density in the middle and lower sections of the regenerator’s dense phase, while the density in the upper part of the dense phase, as well as the density in the dilute phase and at the inlet of the centrifuge, increased. In severe cases, the temperature in the upper part of the three centrifuge waste tank would rise by more than 30 degrees. When the pressure drop across the agent distributor increased, the check valves opened wider; the subsequent measure taken was to reduce the amount of vacuum residue used. Gradually, the situation returned to normal. Therefore, the agent leakage is definitely related to vacuum residue. The preliminary conclusion in the workshop is that catalyst caking has affected its fluidization properties. I would like everyone to discuss possible causes. Vacuum residue has a high tendency to coking and contains high levels of heavy metals. From the information I’ve found, only iron can cause catalyst caking; I would appreciate it if experts could suggest other possible causes
Previously, the workshop experienced catalyst calcium poisoning, resulting in a low yield of light oil as well as leakage of the catalyst. At that time, the analysis also indicated catalyst caking. Are there any other factors that could cause caking?
Could it be that the slag mixing ratio has increased, resulting in more coking in the regenerator? The catalyst circulation rate has gone up as well, which in turn leads to an increase in the main air flow. Consequently, the dilute-phase density in the regenerator increases, exacerbating catalyst loss
There are many reasons for agent leakage in the regenerator, and frequent fluctuations in regenerator pressure are also one of the causes of such leakage.