Hydrocarbon Processing - June 2021 - 59

Sustainability
A. JHA, V. RAVURU, M. YADAV, S. MANDAL
and A. K. DAS, Reliance Industries Ltd.,
Jamnagar, Gujarat, India
A critical analysis of CO2
The use of fossil fuels as a source of energy continues to add
carbon dioxide (CO2
) to the atmosphere, causing detrimenemissions,
and many recapture
technologies, solvent-based
tal effects to the environment. Scientists around the world are
working to reduce the effects of CO2
search efforts are ongoing at both academic and industrial levels.
Among the available CO2
technologies are commercially proven and practiced in many
industries. Despite the commercialization of solvent-based technologies,
research on CO2
capture processes is still vigorously being
pursued to significantly minimize capital and operating costs
per ton of CO2
capture, while improving operational reliability.
capture, with the potential
for CO2
capture
In the last decade, solid sorbents have been recognized as a
very promising technology for CO2
to overcome the existing limitations of solvent-based technologies.
This article highlights the recent developments in commercial
solvent-based technologies and compares their economics
with a proprietary hydrated sorbent processa
recently developed by the authors' company.
Contributing
to global warming and environmental
damage. Rapid industrial growth globally has increased CO2
emissions from pre-industrial levels of 280 ppm to 407.4 ppm
in 2018-up 2.4 ppm since 2017-and is growing rapidly at
approximately 1.5 ppm/yr-2.5 ppm/yr.1
Coal is the secondemissions.
Fossil
emissions.2
largest source of primary energy: China, India and the U.S. have
accounted for 85% of the net increase in CO2
fuel combustion supplies more than 85% of energy for industrial
activities and is the major contributor of CO2
Moreover, fossil fuels will remain the major sources of energy
for the next several decades.
The process of carbon capture and storage (CCS) has the potential
to reduce future world emissions from energy by 20%.3
According to the Global CCS Institute CO2
2018, 23 large-scale CCS facilities were in operation or under
construction, capturing ~40 MMtpy of CO2
.4
separation from flue gas.
RE database, in
The separation of
CO2 from the source consumes approximately 75% of the total
cost of the CCS system, which impacts system implementation.5
Therefore, it is necessary to employ a cost-effective technology
for CO2
Three main techniques are commercially used for CO2
capture:
* A post-combustion capture process, which involves CO2
capture from flue gas after the complete combustion of fuel
* A pre-combustion capture process in which fuel is placed
in the furnace by first converting coal into a clean-burning
gas and stripping out the CO2
released by the process
capture technologies
* An oxyfuel process, which burns the coal in the pure
oxygen-rich atmosphere, resulting in an exhaust gas
with almost pure CO2
.6
Among these technologies, the post-combustion capture
technique involves a higher cost of capture per ton of CO2
, as
it involves the diluted concentration of flue gas (i.e., < 15%).7
Based on the technological readiness level (TRL), the available
post-combustion capture technologies can be classified at various
stages of development.
Abanades, et al., reviewed various CO2
in the context of post-combustion capture, including calcium
looping, chemical looping, post-combustion capture using adsorbent,
solvent and membrane, and concluded that post-combustion
capture is the most mature and successful technique for
CO2
capture using solvent.8
capture technologies
In recent years, the solid sorbent
route is garnering the most attention for use in the post-combustion
capture process due to its inherent advantage of wider temperature
range application from ambient temperature to 700°C,
less waste formation during cycling, and the safe disposal of
spent solid sorbent without undue environmental precautions.7
Published literature on CO2
capture by the adsorption techcapture
nique
using porous organic frameworks, supported alkali metal
carbonate and membranes has shown considerable CO2
capacity. However, the high temperature and resource requirements
to regenerate the solid sorbent negatively influences the
overall cost and time efficiency of the process.9
In this article, the most recent and promising developments
in post-combustion capture technologies that are at pilot and
commercial scale are reviewed critically. Further, the proprietary
hydrated CO2
sorbent processa
Post-combustion CO2
is discussed and compared,
as well as its economic and energy estimates vs. the conventional
and hindered amine process.
capture technologies. The two
major technologies for post-combustion capture are based on
solvents and solid sorbents. These two technologies differ, particularly
in terms of reaction rate, CO2
capture capacity, absorption/regeneration
temperature, capital cost, corrosivity, mass
and heat transfer and stability (thermal, oxidative and chemical,
where chemical stability denotes reactivity against the impurities
present in the flue gas).9
SOLVENT TECHNOLOGIES
The solvent route is based on chemical absorption of CO2
from the source, such as a coal-fired power plant. The developHydrocarbon
Processing | JUNE 2021 59
Hydrocarbon Processing - June 2021

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