Who knows how to deal with liquefied gas in catalytic dry gas?
Thread Content
The dry gas from our plant contains a large amount of liquefied gas, with a concentration of about 5 percent as determined by testing. Many methods have been tried, but none have effectively solved this problem. I’d like to ask everyone for their help in thinking this through.
1. Improve the absorption efficiency of the absorption tower. 2. If no reabsorbent is used in the reabsorption tower, apply an absorbent (diesel is preferred). 3. Keep the temperature at the bottom of the separation tower not too high (usually 110–120°C); otherwise, excessive separation will increase the absorption load.
The load on the absorption and stabilization system is too high; the temperature of the absorption tower is too high, and the pressure of the absorption tower is too low.
1. Excessive rich gas volume results in a low absorption dose and a low oil-gas ratio, leading to poor absorption efficiency; therefore, the flow rate of stabilized gasoline returning to the system should be increased. 2. If the temperature of the stabilized gasoline is too high, reduce the flow rate of the stabilized gasoline back to the system in order to improve the cooling efficiency of the stabilized gasoline cooler. 3. The temperature at the bottom of the desorption tower is too high, causing a large amount of C3 and C4 components to be desorbed into the dry gas. 4. The pressure in the absorption tower and reabsorption tower is too low or experiences significant fluctuations. 5. The liquid levels in the absorption tower and reabsorption tower are too high. This post was last edited by maysee on 2008-1-23 10:17.]
Check whether the trays or packing in the absorption tower are clogged or experiencing flow deviation, as this can easily lead to liquid being carried along with the gas, resulting in a high content of heavier components in the dry gas; we have encountered such problems before.
Let’s clarify the issue: has it always been this way, or did the presence of LPG in the dry gas start only recently? This will help us determine the cause of the problem. I suggest you rule out each possibility mentioned in posts 2 and 4 one by one.
It is possible to increase the top pressure of the tower without affecting the centrifuge; additionally, the amount of absorbent used can be increased or the temperature of the absorbent can be reduced. Reabsorption can be employed – if it is already in use, it is necessary to check whether the level of the reabsorption liquid is correct, as well as the quantity and temperature of the reabsorbent. If the temperature at the bottom of the desorption tower is too high, it can be lowered appropriately.
The temperature at the bottom of the stabilizer is too high; the reflux rate is too low, resulting in poor absorption efficiency. The temperature at the bottom of the desorber is also too high
The pressure in the reabsorption tower should not be lower than 9. The presence of liquefied gas in the dry gas is mainly a problem with the absorption tower, not the reabsorption tower； Is it the fact that the dry gas volume exceeds the design load, resulting in an excessively high linear velocity in the empty tower? The high dry gas volume may be due to poor reaction conditions that result in a high dry gas yield, or excessive desorption in the desorption tower, which leads to a high amount of gas entering the analyzer and thus an increased load on the absorption tower. High temperature in the absorption tower, improper operation of the stabilizer, or poor quality of the supplementary absorbent can all lead to poor quality of the dry gas.