Capturing CO2 from ambient air - David Keith

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B.1.5 Measurement The primary goal of the experiments was to calculate pumping energy, fan energy, and water loss per unit CO2 captured. Accordingly, the quantities we meant to measure were: 1. CO2 uptake 2. liquid flow rate 3. liquid line pressure 4. air flow rate 5. air pressure drops 6. inlet temperature 7. inlet humidity 8. outlet temperature 9. outlet humidity. CO2 uptake was primarily measured by real-time monitoring of the CO2 concentration in air, alternately at the inlet and outlet of the reaction chamber. Measurement points are shown in Figure B.7. Air was pumped continuously from the end of a 1/4 in PE tube inserted at the measuring point through a LiCOR infrared CO2 analyzer. A computer connected to the LiCOR recorded the CO2 reading in ppm every second. This yields a (∼ 3 second delayed) time series of CO2 concentration at the sampling point. Sampling background at the tower inlet was straightforward. Some concerns, however, were raised about whether outlet concentration at any given sample point is representative of the average rate of CO2 capture. Hence, six different points at the outlet were tried. Sampling directly in the reaction chamber proved problematic as drops would get pulled into the sampling tube and bias the measurement. Sampling in the donut appeared to be the most reliable approach. Agreement between the two sampling points and among different depths of tube insertion (5, 10, and 20 cm) was good (the differences were not distinguishable from noise). Agreement between the donut and duct measurements was also good. Measurements from the box and blower tended to run higher (indicating less CO2 absorption) than donut measurements in some trials. This is probably explained by dilution of the process air with room air through leaks in the box and duct connections. Overall, the data used in final calculations appear to be valid representations of average outlet concentration. As a double-check on the LiCOR readings, the quantity of CO2 absorbed into solution for some trials was measured also with a Total Organic Carbon analyzer so that results could be compared. Total liquid flow rate was measured with an inline digital turbine flowmeter for some trials. When this was not available, total flow was estimated from manufacture specifications for the nozzle at the given pressure. Flow of the active spray was taken to be the difference between total flow and dribbler flow. Dribbler flow was measured for some trials by diverting the flow to a 2 L graduated cylinder for 78
Figure B.7: Sampling points of CO2 concentration in air. Arrows indicate position of the end of the sampling tube. Multiple locations for outlet concentration were tested and compared. 79
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Capturing CO2 from ambient air: a f
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For my family, friends, and everyon
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etween the National Science Foundat
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Contents Acknowledgments iv Abstrac
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List of Figures 1.1 Global CO2 emis
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Chapter 1 Introduction The climate
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egeneration at a high enough concen
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1.4 Routes to air capture 1.4.1 Org
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The NaOH approach is the primary su
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there is no compelling reason to ca
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7Na2CO3(l)+5Na2Ti3O7(s) ⇋ 4Na8Ti5
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changing the process design to acco
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Component / source GJ/t-CO2 electri
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Chapter 3 Contactor In this chapter
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the CO2 capture rate in a spray sys
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CO 2 absorption per pass [mol/l] 10
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CO 2 absorption [mmol/pass] 16 14 1
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Figure 3.5: Water loss measured in
Page 37 and 38: 3.3.1 CO2 depletion in air With lon
Page 39 and 40: where vt,1 and vt,2 are the termina
Page 41 and 42: surface area [m 2 -surface / m 3 -r
Page 43 and 44: spray mass density [kg / ln(μm)] 1
Page 45 and 46: average surface area [m 2 -spray /
Page 47 and 48: As a bound on the effects of coales
Page 49 and 50: Draft type Height [m] Crosssectiona
Page 51 and 52: 2. Median assumptions, no coalescen
Page 53 and 54: capture system. We can also see tha
Page 55 and 56: Multistage spray One possible solut
Page 57 and 58: Although, the cost of water loss ma
Page 59 and 60: 3.5.6 Solids formation - scaling an
Page 61 and 62: Chapter 4 Cost of air capture Altho
Page 63 and 64: Capital Capacity Electric a Thermal
Page 65 and 66: Component Capital + O&M Energy cost
Page 67 and 68: Chapter 5 Discussion Overview In th
Page 69 and 70: 5.2 Lessons for assessing of future
Page 71 and 72: Bibliography Adams, P. J. and Seinf
Page 73 and 74: IPCC (2001). Climate Change 2001: M
Page 75 and 76: Tzivion, S., Feingold, G., and Levi
Page 77 and 78: F Liquid flow rate in the contactor
Page 79 and 80: Appendix B Experimental details and
Page 81 and 82: Figure B.2: Photograph of completed
Page 83 and 84: Figure B.4: Two cranes lift the rea
Page 85 and 86: fastened together and lined, the re
Page 87: The prototype has three particle fi
Page 91 and 92: In order to calculate CO2 absorbed,
Page 93 and 94: Absorbed CO 2 [mol/l] 0.3 0.25 0.2
Page 95: periodic switching of the spray on
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Capturing CO2 from ambient air - David Keith

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