3 replies to this topic

[ganesh2009kumar]

hi...
i am doing a project on co2 capture from atmosphere. please suggest some easy techniques to estimate the amount of co2 present in the air. we are using planning to use mono ethanol amine for co2 scrubbing. will this process be efficient? . we have chosen a packed column of height 50 cm and diameter 10 cm. Is this dimension of the packed column is enough for the scrubbing process?.
explain easy techniques for estimation of the co2 at the inlet and outlet of the column.

regards.
ganesh

[Art Montemayor]

ganesh:

I started my engineering career capturing and producing food grade CO₂ – and I designed, installed, and operated many units over the years. Since this thread is in the Industrial professionals, I’ll make my comments as I would to any professional engineer in the business, although the query seems to come from a student or a lay person:

• You don’t present sufficient nor detailed basic data; this does not allow for constructive comments.
• We should all know the average composition of CO₂ in the atmosphere – as mentioned in the literature, it is miniscule. And it depends on where you take the sample – in a crowded room or in desert, or on a mountain top.
• What do you mean by “efficient”? Please be specific. Do you mean economically efficient? If so, the answer is certainly NO. If you mean whether the MEA will absorb a LOT of CO₂ at the relatively weak concentration in air, then the answer is that it will probably absorb more than other absorbents, but that depends on process conditions and what you call a LOT.
• As an engineer, you should be aware that without telling us your process flow rates, temperatures, pressures, and compositions we can’t even GUESS what the dimensions of your absorber should be. This is a not an engineering query. It is more of a layman’s naive question.
• There are no “easy” techniques for estimating the CO₂ composition in the absorber outlet. You should run a process simulation on the proposed process and see if it works. I seriously doubt it will.

[kkala]

In addition to above post, in case that your query also asks "how to measure CO2 of the air ingoing or leaving the packed column", have a look at http://www.cheresources.com/invision/topic/11264-lab-scale-pilot-plant-design/, as well as the attached "labequip.doc". The measuring apparatus consists mainly of an air cooler, air pump, analyser and gas meter (similar to those for natural gas metering, soon to be replaced due to corrosion). The analyser is actually a series of barboters, full of pure, dilute NaOH solution. Any condensate from cooler should also be mixed with NaOH solution during collection (ie during the measurement).
Barboters can be supplied from a good shop of lab equipment, also selling air pumps (of stainless steel) and glass coolers using raw water. I am not certain that cooling is feasible in the specific case, yet any gas cooling will reduce humidity, hence corrosion in the downstream gas meters (speaking of lab equipment only).

Edited by kkala, 08 June 2012 - 10:08 AM.

[Technical Bard]

Google can tell you that the concentration of CO2 in the atmosphere averages about 385 ppmv and it is rising slowly.

Removal of CO2 from the atmosphere using amine is unlikely to be very effective, as the partial pressure of CO2 is extremely low due to the low concentration. Amine can be used in flue gas applications because the concentrations are many PERCENT and there is more driving force.