How to judge excessive absorption and excessive desorption in catalytic operation?
Thread Content
Based on which parameters can we judge whether the absorption tower is over-absorbing or the desorbing tower is over-desorbing? How much should we control the bottom temperature and top temperature of the desorption tower of our catalytic cracking unit?
Consider the content of c3 or above in dry gas
The manifestation of excessive absorption is that even if the other parameters remain unchanged, even if the bottom temperature of the desorption tower is higher than usual, the pressure of the stable tower will not be avoided, the C2 content in the liquefied gas will increase, and the amount of non-condensable gas in the liquefied gas reflux tank will increase.； The manifestation of excessive desorption is that the desorption gas flow rate at the top of the desorption tower increases. Even if the load of the absorption tower is very large, the content of C3 and C4 components in the dry gas cannot be avoided. The pressure of the stabilization tower decreases to varying degrees, and there is almost no C2 in the liquefied gas. In actual operation, we need to rely on rich experience to judge. For example, if the content of C3 and C4 components in dry gas increases, it may be caused by excessive desorption, or the heat extraction effect of the middle section is reduced, or it may be caused by the quality reduction of the absorbent, or it may be caused by the change of absorbed dose, etc. Therefore, when judging the cause of abnormal phenomena in operation, we must integrate as many known conditions as possible and use the elimination method to find out the problem. Please correct your personal understanding.
The third floor made it very clear, it is mainly determined by analyzing the ingredients.
1. It is judged by the quality of dry gas and liquefied gas. 2. Excessive absorption and insufficient analysis will bring C2 into the stabilizing tower, causing the stabilizing tower pressure to exceed the pressure, forcing the liquefied gas reflux tank to discharge non-condensable gas. 3. The analysis should not be excessive. The increase of C3 and above components in the dry gas will increase the load of the absorption tower and waste the heat source of the analysis tower. 4. When adjusting the quality, in addition to paying attention to the pressure of each tower, you must also pay more attention to the parameters of desorbed gas volume, dry gas volume, absorption tower top temperature, analysis tower bottom temperature, and stable tower top temperature and post-cooling temperature. Gradually find out the appropriate operating conditions.
Excessive absorption and insufficient analysis will bring C2 into the stabilizing tower, causing the pressure of the stabilizing tower to fluctuate or even overpressure, forcing the top reflux tank of the stabilizing tower to discharge non-condensable gas.
Mainly rely on quality analysis and experience to judge material balance.