Final Year Project

1. DIRECT AIR CAPTURE OF
CARBON DIOXIDE
let's Reverse Climate Change
GHULAM ISHAQ KHAN INSTITUTE OF ENGINEERING SCIENCES & TECHNOLOGY
Department of Chemical Engineering
TALHA RAFIQUE (2017475)
ABDUL REHMAN VIRK(2017012)
ALI KHAN LODHI (2017064)
SAMIULLAH SHEIKH (2017409)
ADVISOR: DR. MUHAMMAD SHOZAB MEHDI
CO-ADVISOR: IMRAN ABBAS

2. 1800 1850 1900 1950 2000 2050 2100
800
600
400
200
0
C
0
2
c
o
n
c
e
n
t
r
a
t
i
o
n
(
p
p
m
)
Historical and predicted C02 emissions
by Scripps Institution of Oceanography
Problem Overview
2
Now or Never; Are We to Live or Perish Forever?
Carbon Dioxide: The No. 1 Greenhouse Gas
Carbon dioxide is accounted for about 81.3
percent of all greenhouse gas emissions from
human activities (The United States
Environmental Protection Agency, 2018).
36–70% of the greenhouse effect is due to
carbon dioxide in the Earth's atmosphere
(IPCC, 2017).

3. Process Description
3
(Keith, et al., 2018)

4. Material Balance
Specie Inlet(kmol/hr) Reacted Outlet(kmol/hr)
CO2 3880 2910 970
KOH 7760 5820 1940
H2O 0 2910 2910
K2CO3 0 2910 2910
X = 0.75, Conversion of Carbon dioxide
Air Contactor Mole Balance
Specie Inlet(kmol/hr) Reacted Outlet(kmol/hr)
CaO 2595.138 2205.8673 389.2707
H2O 2595.138 2205.8673 389.2707
Ca(OH)2 0 2205.8673 2205.8673
X = 0.85, Conversion of Calcium Oxide
Lime Slaker Mole Balance
which is the basis of this material balance.
Specie Inlet(kmol/hr) Reacted Outlet(kmol/hr)
K2CO3 2910 2648.1 261.9
Ca(OH)2 2910 2648.1 261.9
KOH 0 5296.2 5296.2
CaCO3 0 2648.1 2648.1
X = 0.91, Conversion of Potassium Carbonate
Pellet Reactor Mole Balance
Specie Inlet(kmol/hr) Reacted Outlet(kmol/hr)
CaCO3 2648.1 2595.14 52.962
CaO 0 2595.14 2595.138
CO2 0 2595.14 2595.138
X = 0.98, Conversion of Calcium Carbonate
Calciner Mole Balance
4
2595.138 kmol/hr Carbon dioxide approximates to 1 Million tons of carbon dioxide captured per year,

5. Main Flowsheet of Aspen Plus Simulation
5

6. PROPERTY METHOD
• Electrolyte NRTL (Non-Random Two-Liquid), applied for the liquid phase.
• SRK EOS (Soave-Redlich-Kwong Equation of State), applied for the gas phase.
CHEMICAL REACTIONS
Reactions generated by Aspen Plus® Electrolyte wizard
REACTION TYPE
H2O + HCO3- ↔ CO3
2- + H3O+ Equilibrium
CaOH+ ↔ Ca2+ + OH- Equilibrium
2 H2O + CO2 ↔ HCO3- + H3O+ Equilibrium
2 H2O ↔ OH- + H3O+ Equilibrium
K2CO3 ↔ CO3-2 + 2 K+ Salt
CaCO3 ↔ CO3-2 + Ca+2 Salt
KOH → OH- + K+ Dissociation
Ca (OH)2 → CaOH+ + OH- Dissociation
6

7. Air
0.06% C02,
23% O2,
75.96% N2
0.98% H20
KOH solution
0.101 % KOH
0.899% H20
O2
N2
CO2
K2C03
Towards
Pellet
Reactor
AIR CONTACTOR
0
500
1000
1500
2000
2500
3000
3500
4000
4500
0 0.05 0.1 0.15 0.2 0.25
CO2
absorbed
(kmol/hr)
Wt.% KOH
Effect on Carbon dioxide absorbance by
varying KOH wt.% generated by
using Sensitivity Analysis on Aspen Plus
7

8. Effect on Conversion of Carbonate ions by varying calcium hydroxide wt.% generated by
using Sensitivity Analysis on Aspen Plus
0
0.2
0.4
0.6
0.8
1
1.2
0 0.1 0.2 0.3 0.4 0.5 0.6
Conversion
CO3
ions
to
CaCO3
wt% Ca(OH)2
Pellet Reactor
8

9. CaCO3
Seed
Ca(OH)2
KOH
K2C03
CaCO3
Towards
Calciner
CaCO3
Draw off
9

10. Calciner Section
10

11. Slaker Section
11

12. CO2 Compression Section
Specie Mol flow (kmol/hr) Mol%
Carbon Dioxide 3498.661 0.954
Oxygen 77.21755 0.021
Nitrogen 91.8834 0.025
Temprature 45 Celsius
Pressure 150.0625 Bar
Final Stream Temperature Pressure
12

13. Power Generation Section
13

14. References
• Keith, D. W., Holmes, G., Angelo, D. S., & Heidel, K. (2018). A Process for Capturing CO2 from
the Atmosphere. Joule, 2(8),1573-1594. doi:10.1016/j.joule.2018.05.006
• Beuttler, C., Charles, L. & Wurzbacher, J., 2009. The Role of Direct Air Capture in Mitigation of
Anthropogenic Greenhouse Gas Emissions. Frontiers in Climate, Volume 1, p. 10.
• M. Ranjan and H. J. Herzog, “Feasibility of air capture,” Energy Procedia, vol. 4, no. 2010, pp.
2869–2876, 2011.
• de Jonge, M. M. et al., 2019. Life cycle carbon efficiency of Direct Air Capture systems with
strong hydroxide sorbents. International Journal of Greenhouse Gas Control, Volume 80, pp. 25-31.
• United Nations, 2015. The Paris Agreement.
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