Absorption stability
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Hello everyone. Recently, I read some articles and flowcharts, and noticed that in some absorption and stabilization processes the temperature at the bottom of the desorption tower is only around 125–135°C, while in other cases it can reach 180°C. There’s a huge difference between these values. Why is that? It shouldn’t make much difference even if the pressure is different, right? With such high temperatures, the amount of C3 and C4 entering the absorption tower must be quite high, right? (In a process where the temperature at the bottom of the desorption tower is 180°C, the temperatures in the other towers are also considerably higher, ranging from 125 to 135°C or so.) Please give me your advice: handshake
The requirements for this design still need to be considered in terms of both the reflux rate and the control of the top temperature of the tower. A high bottom temperature means that the temperature at the top of the tower will be lower, and the reflux ratio will need to be much higher. If the control requirements regarding the concentration of the C2 component are not very strict, it is possible to reduce the bottom temperature slightly while adjusting the reflux rate to see whether this can meet the requirements. A high bottom temperature implies higher energy consumption to some extent.
The temperature at the bottom of the desorption tower is 180 degrees; is the operating pressure of the tower 1.0–1.2 MPa?
I initially had the same doubts, as the pressure of the desorption tower wasn’t indicated in that diagram; then I checked the pressures of the other towers, and they were all at normal pressures corresponding to stable absorption conditions. There’s no need to increase pressure on one hand while raising the temperature on the other.
It is set based on the processing volume and product quality; while ensuring that the product quality remains satisfactory, the temperature at the bottom of the desorption tower can be appropriately reduced, which not only lightens the load on the absorption tower but also saves energy
I conducted simulations for absorption stabilization, and the results showed that a temperature as high as 187 is not necessary at the bottom of the distillation column; C2 can be controlled well at lower temperatures. So when I see some flow diagrams showing such high bottom temperature values, it seems really strange to me; I’m not sure what the reasoning behind that is. Or have I missed something in my consideration?
Pay close attention to the analysis of the tower top temperature; monitor both the tower top temperature and the reflux volume.
It has something to do with design, I guess. Some desorb 15 kilograms, some 17 kilograms.
The temperature difference at 15 kg of pressure and 17 kg of pressure won’t be that great
There is also a common range of 1.1~1.2 MPa
This has a lot to do with the composition of the raw materials. I just hope to hear what everyone has to say, in case there’s something I haven’t thought of