User talk:JoseZZ/sandbox

Peer Review Feedback

I liked your article and thought the sections were well thought out and the examples provided were interesting. I hadn't thought very much before about applications for hybrid processes and think your description of what is going on at UT Austin was a solid practical example. As for areas to improve I think the cascade process was well described but would be more clear to the reader if a diagram was included. Also, in the second paragraph of Membrane Use in Hybrid Processes there is a minor grammar error in the 3rd sentence (is also,). I think you could expand a little more about what cryogenic technology you are referring to, as the linked page doesn't provide the reader any clarity. The last paragraph was incredibly strong and provided the reader with a good view of cost comparisons, though the title of the section is very long and could be summarized more. Good job overall! (Tressamikel (talk) 21:49, 2 May 2017 (UTC))

Direct Air Capture (DCA) Process Example using NaOH

Figure 1: This PFD summarizes the main steps in a DCA processes that uses NaOH (aka Caustic Soda) as the absorber.

This processes is outlined by Figure 1.

The chemistry of this process is explained in the "Sodium Hydroxide" section in the Carbon dioxide scrubber page. In short, CO₂ from the air is chemically dissolved into NaOH(aq) solution as Na₂CO₃; the Na₂CO₃ is then reacted with solid Ca(OH)₂, which regenerates the solvent and produces CaCO₃ crystals; lastly, heat is applied to the CaCO₃ crystals to produce pure CO₂ gas.

Air is pumped through the CO₂ absorber as the first step of this process. CO₂ absorber for DAC are designed either as a counter-current spray tower or as a counter-current thin-falling-film contractor to maximize the contact area between the air and the solvent and thus maximize the absorption driving force.  The solvent is regenerated in the causticization unit by reacting the Na₂CO₃ with Ca(OH)₂, which also transfers the captured CO₂ to the form of CaCO₃ solid crystals.  A mechanical filter is then used to separate the CaCO₃ crystals form the water.  Since the crystals come out wet from the filter, they are dried in a steam dryer.  Then the dry crystals are heated in a furnace to produce CaO and pure CO₂ gas. The CaO is then hydrated to regenerate the Ca(OH)₂ used for the causticization reaction. The pure CO₂ stream is then compressed and ready to be transported for geologic sequestration, EOR, or other commercial applications.

1 M NaOH (aq) is a typical solvent concentration because this concentrations is limited by the causticization reaction that regenerates the solvent it is not too far from the practical maximum of 2 M NaOH. The furnace/kiln can be powered renewably or by burning fuel on-site with pure oxygen produces in a on-site air separation unit.

NaOH is economically competitive with other absorbents (e.g. Amines) used for DAC processes. DAC processes are energy intensive. Calcination (at the furnace) is the most energy intensive step of this process.

 

To consider for main project (CBE 195, S2017):

A. https://en.wikipedia.org/wiki/Membrane_gas_separation

1. Section: Membrane Materials for Carbon Capture in Flue Gas Streams

- Hybrid Membranes

2. Section: Current Status of CO2 Capture with Membranes

- Backup/ alternative Process Design

Go in depth on Dr. Baker’s process design for membrane separation.  We have many of his articles at our disposal

B. https://en.wikipedia.org/wiki/Carbon_capture_and_storage

3. Section: CO2 Separation Technologies

Add content about membranes Article says membrane technology is “still in the developmental phase,” then links to the gas separation article.  There is potential to include add material here, while linking to the gas separations page.