Seeking advice on the design of activated carbon adsorption towers
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It’s my first time working on a design, and I need an activated carbon adsorption tower. The principle behind such towers seems simple, but I’m not sure if I can build one by myself. If I do decide to try, what should I keep in mind? The specific situation is as follows: the gas flow rate is variable, with a maximum of no more than 1500 cubic meters per hour; the gas mainly contains pollutants of the gasoline type. Moreover, this adsorption tower will not be used for a long time, at most one year, so the regeneration of activated carbon is not considered. The gas is discharged from a vortex air pump and enters the adsorption tower. I would like to ask everyone: under such circumstances, how should the diameter, height, volume, etc. of the adsorption tower be designed? Thank you all!
Reply to 1# holmes8519: How should the diameter, height, volume, etc. of an absorption tower be designed? Thank you all! This depends on the particle size of the adsorbent you choose, its dynamic adsorption capacity, the volume of gas, the concentration of oil and gas in the gas, as well as the treatment requirements. I can’t say much since you don’t have any data.
Reply to 3# HanGuangDuanShui: My situation is rather complex; as I am engaged in research, the gas flow rate varies. The maximum flow rate of the gas pump selected is 1940 m³/h, but this value will certainly not be reached. It’s also difficult to determine the concentration in the exhaust gases. Based on experience, the concentration of total petroleum hydrocarbons can reach up to 5000 ppm. Since the gas comes from underground, the relative humidity is high. The exhaust emissions need only meet the **emission standards GB16297－1996; that is, the level of petroleum hydrocarbons should not exceed 150 mg/m³. May I ask whether the particle size of activated carbon has a significant impact on its effectiveness? What factors are mainly affected? Pressure drop? Adsorption efficiency?
Reply: HanGuang DuanShui. The maximum flow rate of the selected air pump is 1940 m³/h, but this value will certainly not be reached. It’s difficult to determine the concentration in the exhaust gas; based on experience, the concentration of total petroleum hydrocarbons can reach up to 5000 ppm. Since the gas comes from underground, the relative humidity is high. The exhaust emissions need only meet the **emission standards GB16297－1996; that is, the level of petroleum hydrocarbons should be 150mg/m³. I would like to ask: does the particle size of activated carbon have a significant impact on its effectiveness? What factors are mainly affected? Pressure drop? Adsorption efficiency? 5000 PPM means that 1 cubic meter of exhaust gas contains 5000 ml of pure hydrocarbons. Assuming the average molecular weight of hydrocarbons is 100 (this value is necessary to know), under standard conditions, (5/22.4)*100 = 22.32. According to the emission standards, 22.32 – 0.15 = 22.17 grams per cubic meter should be absorbed. This amounts to 43 kg per hour. Considering an adsorption efficiency of around 15% for activated carbon, 286 kilograms of activated carbon are required, which translates to 6 tons per day! ! ! ! It seems impossible to avoid regeneration with this amount; the key issue is that your concentration of 5000 PPM is too high. Even though the volume of gas isn’t large, a high concentration results in a significant amount of adsorption. The particle size of activated carbon is related to the flow rate of the gas through the bed during adsorption as well as the pressure drop, and it is an important parameter for calculating the diameter of the tower and the height of the bed.
Reply to 4# Han Guang Duan Shui – Thank you so much! Your calculation is excellent!
Reply to 5# holmes8519: http://bbs.hcbbs.com/viewthread.php?tid=521334&extra=&highlight=&page=1. This post is one I previously posted discussing a process scheme for using activated carbon adsorption towers to remove toluene; you can take a look at it.
Reply to 6# Han Guang Duan Shui: I’ve learned it, thank you so much!
It’s well written; I just don’t know the specifications and models of the activated carbon.