Pressure issues in the catalytic cracking absorption and stabilization system
Thread Content
The pressure in the catalytic cracking absorption and stabilization system is generally around 10 kilograms. Is it possible to reduce this pressure, as well as the temperature? Analyze the reasons
Low temperatures are favorable for absorption, but low pressure affects the absorption efficiency
It should be possible; the key is to reduce the temperature at the top of the tower, so that the pressure there can be lowered. Otherwise, it will result in excessive levels of heavier components in the LPG product.
It depends on the specific procedures; high pressure is beneficial for absorption and can reduce liquid carried in the dry gas； However, it is not conducive to analysis; poor analysis results can cause the carbon dioxide component to enter the stabilizer, affecting its operation. Lowering the temperature can also improve the absorption efficiency, but it increases the heating load at the bottom of the separation tower. This requires finding the balance point, that is, the optimal operating scheme, by considering various parameters during operation. Devices vary from one another; a one-size-fits-all approach won’t work. As long as one makes an effort to explore and learn, the stable system will operate very smoothly.
High pressure is favorable for absorption but unfavorable for separation, affecting the operation of the stabilizer. Lowering the temperature can also improve the absorption efficiency, but it increases the heating load at the bottom of the separation tower. It can be adjusted according to the cooling load, and experimental adjustments can be carried out to determine the optimal operating parameters of the device.
The level of pressure in the stabilizer is determined by the composition of the product desired as a result of the reaction; high pressure facilitates absorption but hinders separation, and there is a balance point to be achieved in actual operation.
It depends on how low you want to bring it: the temperature at the top of the absorption tower should be between 15 and 50, with a pressure of 1.0 to 1.3; the temperature at the top of the desorption tower should be between 48 and 80, while the temperature at the bottom of the desorption tower is between 115 and 150, with a pressure of 1.1 to 1.4. The temperature at the top of the stabilization tower should be between 50 and 75, and the temperature at its bottom between 155 and 190, with a pressure of 0.9 to 1.05. The parameters can vary greatly; adjust them according to the requirements of the product. Lower temperatures are favorable for absorption but not for desorption, and increasing the load on the desorption tower is necessary to ensure stable operation. High pressure facilitates absorption but hinders desorption
As long as the dry gas, liquefied gas, and gasoline are of acceptable quality, the pressure can be reduced appropriately
This post was last edited by Barber Trains Apprentice on 2010-7-20 08:54. The temperature should correspond to the pressure; qualitatively speaking, it is correct and feasible to reduce both the pressure and the temperature, depending on how low the temperature can be reduced. Regarding absorption, if the pressure in the reabsorption tower or absorption tower is low and more C3 ends up in the dry gas, what should be done? The temperature can be lowered; it then depends on how much it’s possible to reduce the temperature, or adding more trays might be an option. A lower pressure in the separation tower is advantageous, but when the pressure drops, C2 will escape, and it’s possible that more C3 will also escape; therefore, it’s appropriate to reduce the temperature slightly. For the stabilizer column, it is necessary to ensure that the liquefied gas is in a liquid phase under operating conditions, so as to guarantee reflux; accordingly, the temperature and pressure must be fixed.
It is entirely possible to reduce the pressure; when our catalytic system was first set up, we used an old compressor, and we could only control the pressure at the top of the absorption tower at 0.75 MPa. At the beginning of operation, it was difficult to keep the content of components above C3 in the dry gas below 5%; by increasing the absorption dose and modifying the tower, we managed to reduce this value to below 1%. At the beginning of operation for our second set of catalysts, the pressure at the top of the absorption tower was also controlled at 0.8 MPa following *conventional practices, and the dry gas content remained above C3 but below 1%.
This is mainly related to the processing volume; when the processing volume is high, reducing the pressure will result in an excessively high line speed, which in turn causes a large amount of liquid-phase components to be carried up to the top of the absorption tower, thereby hindering the yield of light oil.