Absorption tower in the purification section
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In the low-temperature methanol washing process, if the acid gas absorption tower is a single tower with the upper section primarily used for absorbing CO2 and the lower section primarily used for absorbing H2S, can it be divided into upper and lower sections during the design calculations, treating each section as a single-component absorption process? In other words, can we ignore the absorption of H2S in the upper section and the absorption of CO2 in the lower section?
The upper section does not need to take into account H2S absorption, but the lower section must consider CO2 absorption; the amount of CO2 absorbed in the upper and lower sections is roughly the same
I think CO2 absorption can be disregarded, as the main task of this section is to absorb H2S; achieving the design goal is sufficient as long as all the H2S is absorbed!
The main control in the lower section is the absorption of H2S; the amount of CO2 absorbed is not important, as CO2 absorption primarily takes place in the upper section.
The impact of CO2 should be taken into account in the lower section, because pure methanol and methanol that has absorbed CO2 have different capacities for absorbing H2S! I’m not sure if it’s like this!
I think what the original poster is asking is whether, in the design of this downflow absorption tower, it is still necessary to take into account methanol’s ability to absorb CO2. I think he must also have designed it to use rich methanol to absorb H2S. The focus of his question was whether, after designing a system to produce sufficient methanol rich in H2S, it would still be necessary to consider using some livestock to absorb CO2.
I think the methanol rich in carbon used for absorbing hydrogen sulfide comes from the carbon dioxide absorption section; this methanol has an extremely low capacity to absorb carbon dioxide in the hydrogen sulfide absorption section, to the point where it can be ignored
Is the main discharge outlet of the absorption tower at the bottom of the tower? In actual production, is there a sulfur-enriched methanol CO2 desorption tower at the lower end of the CO2 absorption section in the upper part of the absorption tower? Is the amount of material discharged from this tower large? In the design calculations, can I ignore this portion of the output and assume that all the output is at the bottom of the tower? Does the output first go to the CO2 desorption tower, and then the sulfur-rich methanol from the bottom of the CO2 desorption tower goes to the H2S concentration tower? (This is done because calculations without a side-line outlet are much simpler.) Last edited by xkzzj on 2009-3-19 10:29 in this post.]
Generally, the rich methanol from the upper column is refluxed back to the lower column! I think you can’t ignore it. Also, there is side-line extraction at the top of the tower – how do you design that?
Where does the side-stream output from the upper tower go? Is it to discharge the material from the upper tower due to the temperature rise caused by the heat of dissolution of methanol, in order to carry out heat exchange and cooling?
The methanol washing tower is divided into an upper tower and a lower tower, with the lower tower being primarily used for desulfurization. Since the solubility and dissolution rate of H2S and COS in methanol are much higher than those of CO2, only the methanol solution that has absorbed CO2 in the upper column is required for desulfurization in the lower column, with a volume accounting for about 50% of the total amount. The methanol solution, which has been washed in the lower tower and absorbed all of the sulfur, is discharged from the bottom of the tower; most of the H2 in the methanol solution is removed there by cooling and vacuum flashing.
After the side stream from the top of the tower is taken out, it returns to the tower after being cooled, so it also needs to be calculated in segments. The upper tower is divided into 3 sections.
It’s a bit dizzying to watch! ! ! ! ! How is the design process calculated? Why not consider the amount of CO2 at the tower? If there’s no amount for going down the tower, how can we calculate it for going up the tower? ? ? Both carbon dioxide and hydrogen sulfide are saturated in the lower tower! The amount of carbon dioxide in the upper tower is the total amount minus the amount in the lower tower, right? Even if you don’t count the amount of the lower tower? So what do you do with the carbon dioxide that is stripped out at the bottom of the T3 tower behind it? ? How is the carbon dioxide level calculated?