Questions regarding the catalytic desorption tower
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Why is the feed to the desorption tower of the catalytic unit supplied through two separate paths? I have installed a desorption tower with 30 layers, equipped with two feed streams (at the first and seventh layers); the ratio of the flow rates of these two feed streams is 2:5, with the feed to the seventh layer being heat-exchanged. What impact does this have on the desorption process? In operation, it is common to encounter the problem that raising the bottom temperature of the tower leads to excessively high top pressure, while lowering or not adjusting the bottom temperature results in an excess of non-condensable gases at the top of the stabilizer, causing overpressure. Please help find a solution to this issue.
I have worked in catalysis before; the two feed streams seem to be designed taking into account the temperature differences between winter and summer. I can’t figure out the specific reason; you can think carefully along this line of thought. .
The two feeding methods mentioned by the original poster have little impact on our actual operations. As for the issues of temperature and pressure you mentioned, I think there are some problems with the operation of your absorption tower; the phenomena you described are caused by excessive absorption. You can try reducing the absorption dose and increasing the temperature at the top of the absorption tower.
We use thermal feeding to the distillation column only when there is insufficient heat source at the bottom of the column, the temperature is low, and the distillation efficiency is poor. They are generally in standby mode. The phenomenon mentioned by the poster is likely an imbalance in the analysis tower’s balance, resulting in excessive or insufficient analysis.
Cold material is fed at the top of the tower, while hot material is fed in the middle. Energy is utilized to the fullest extent; the hot feed reduces the reboiling load at the bottom of the tower. The cold feed at the top takes advantage of the available cold energy. Check the temperature distribution within the tower.
Feeding in two streams makes full use of the heat. The temperature varies at different locations in the tower; therefore, feed materials at different temperatures are fed at different locations as well. However, it is necessary to conduct calculations to determine whether the mass transfer task can be completed. Due to fluctuations in the feed components, the temperature at the bottom of the tower sometimes needs to be adjusted; however, this causes changes in the pressure at the top of the tower. To improve this situation, it is necessary to speed up the response time of the pressure control system at the top of the tower, in order to prevent pressure buildup.
In operation, it is common to encounter the problem that raising the bottom temperature of the tower leads to excessively high top pressure, while lowering or not adjusting the bottom temperature results in an excess of non-condensable gases at the top of the stabilizer, causing overpressure. Please help find a solution to this issue. Raising the temperature at the bottom of the stripping tower leads to excessive stripping effects; whereas keeping the temperature low or not adjusting it results in an excess of non-condensable gases in the stabilizing tower, which keeps the pressure in that tower high. The main reason is that it is necessary to maintain appropriate temperatures in all three towers, with the temperature at the bottom of the stripping tower generally being around 160 degrees
To address the issue of excessive desorption, reduce the proportion and temperature of the hot feed, and increase the proportion of the cold feed, provided there are no problems with the heat source at the bottom of the tower. If the heat source is insufficient, it is still necessary to increase the amount of heat input; when excessive desorption occurs, it is a gradually worsening process similar to a snowball effect. The solution is to significantly reduce the heating load at the bottom of the tower, at the expense of quality. Replace the components in the intermediate condensate tank to restore the normal composition. An old problem.
I’ve learned a lot again; thank you all!