13 research outputs found
Understanding the impact of solvent properties and process design on the cost of CO2 capture for absorption systems
No full textCarbon capture and storage (CCS) is one of the technologies that may enable large-scale fossil fuel power generations and industries to stay economically viable while reducing their CO2 emissions. Currently, the cost of CO2 capture using chemical absorption, the most promising technology for post-combustion CO2 capture, is high and improvements in absorption technology are essential to make CCS competitive.
The objective of this thesis is to evaluate the impacts of solvent parameters and process configurations on performance and costs of absorption systems to identify areas for future development. This is achieved by performing a high-level assessment of two solvent classes (aqueous and phase-change) in a conventional and an encapsulated solvent system.
For aqueous solvents in a conventional absorption system, cost reductions through improvements in process design are smaller than reductions through improvements in solvent properties. Among the solvent properties, solvent stability to SOx and NOx, heat of reaction, solvent concentration, and solvent working capacity have the largest influence on CO2 capture cost.
For phase-change solvents in a conventional absorption system, cost reductions can be achieved when the CO2 absorption process is operated in a packed column and low-grade heat is utilised to fully supply the dissolution heat exchanger duty. Using this configuration, the capture cost for phase-change solvents can be up to 40 % lower than that of current estimates using MEA 30 %-wt.
For encapsulated solvent systems, the capture cost using MEA 30 %-wt. can be up to double the cost of using the same solvent in a conventional absorption system. Among the different configurations investigated, using a fluidized-bed configuration coupled with heat recovery between the rich and lean sorbent streams resulted in lower costs than the alternate fixed-bed configuration. In order for encapsulated solvent systems to be economically competitive, improvements in heat recovery, a thinner capsule shell, and novel absorber and regenerator columns are necessary.
The results of a Monte Carlo analysis show that to achieve significant cost reductions, new solvents do not necessarily require superior values for all properties and various combinations can be used. However, in general it was found that all solvents require good stability towards SOx and NOx, low heat of reaction and water vaporization, as well as being inexpensive
Solvent Development for Post-Combustion CO<sub>2</sub> Capture: Recent Development and Opportunities
No full textChemical absorption is widely regarded as the most promising technology for post-combustion CO2 capture from large industrial emission sources with CO2 separation from natural gas using aqueous amine solvent system having been applied since the 1930s. The use of monoethanolamine (MEA) in CO2 absorption system possesses several drawbacks, such as high regeneration energy, high solvent loss, and high corrosion tendency. Various solvents have been developed for post-combustion CO2 capture application including the development of aqueous solvents and phase-change solvents. Some of these alternate solvents have been reported to have better solvent properties, which could improve the CO2 absorption system performance. This paper reviews key parameters involved in the design improvement of several chemical absorption process systems. In addition, some novel solvent systems are also discussed, for example encapsulated solvents systems. Some of the key solvent parameters that affect the capture performance, such as heat of reaction, absorption rate, solvent working capacity, solvent concentration, and solvent stability, are discussed in this paper, particularly in relation to the economic viability of the capture process. In addition, some guidelines for the future solvent development are discussed.</jats:p
Solvent Development for Post-Combustion CO2 Capture: Recent Development and Opportunities
No full textChemical absorption is widely regarded as the most promising technology for post-combustion CO2 capture from large industrial emission sources with CO2 separation from natural gas using aqueous amine solvent system having been applied since the 1930s. The use of monoethanolamine (MEA) in CO2 absorption system possesses several drawbacks, such as high regeneration energy, high solvent loss, and high corrosion tendency. Various solvents have been developed for post-combustion CO2 capture application including the development of aqueous solvents and phase-change solvents. Some of these alternate solvents have been reported to have better solvent properties, which could improve the CO2 absorption system performance. This paper reviews key parameters involved in the design improvement of several chemical absorption process systems. In addition, some novel solvent systems are also discussed, for example encapsulated solvents systems. Some of the key solvent parameters that affect the capture performance, such as heat of reaction, absorption rate, solvent working capacity, solvent concentration, and solvent stability, are discussed in this paper, particularly in relation to the economic viability of the capture process. In addition, some guidelines for the future solvent development are discussed
Understanding the Impact of Process Design on the Cost of CO2 Capture for Precipitating Solvent Absorption
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Reducing The Cost of CO2 Capture From Flue Gases Using Phase-change Solvent Absorption
No full textAbstractThere has been increasing interest in the development of alternative solvents for CO2 capture, including solvents that involve precipitation during CO2 absorption. Based on the precipitating species, there are two classes of phase- change solvents. One of the benefits of using phase-change solvents is the opportunity to use low grade heat (around 80°C or higher) for precipitate dissolution. The objective of this paper is to carry out a cost-benefit analysis of phase-change solvents for CO2 capture. For each phase-change solvent class, multiple levels of heat integration are considered and their impact on total heat duty is quantified
Selective H2S Absorption Using the Mixture of NaOH-NaHCO3-Na2CO3 Buffer Solvent Solution
No full textAcid gas enrichment unit (AGEU) involves selective separation of H2S from acid gas mixture, for example using absorption with an NaOH solvent solution. Sodium carbonate (Na2CO3) and sodium bicarbonate (NaHCO3) buffer addition to NaOH solution suppresses CO2 absorption, thereby increasing the selectivity of H2S absorption. This study evaluated the effect of buffer addition to increase H2S absorption selectivity using an NaOH solution. It was shown that both buffer addition and L/G ratio decrease could increase H2S selectivity by limiting CO2 absorption. Based on the simulation results, in the 0.006 to 0.030 L/G ratio range and NaOH solvent concentration greater than 2%-mass, the addition of NaHCO3 with mass ratio greater than 1.5:1 to NaOH and the addition of Na2CO3 at 1.26 times NaHCO3’s mass increased H2S absorption selectivity up to 17.3%. The combination of an L/G ratio of 0.006 and solvent with a composition of 5%-mass NaOH, 15%-mass NaHCO3, and 18.9%-mass Na2CO3 produced the highest H2S selectivity of 23.1 (379.7% H2S selectivity increase)
Understanding the Impact of Process Design on the Cost of CO<sub>2</sub> Capture for Precipitating Solvent Absorption
No full textThere has been increasing interest
in the development of solvents
for CO<sub>2</sub> capture including solvents that involve precipitation
during CO<sub>2</sub> absorption. On the basis of Le Chatelier’s
principle, the CO<sub>2</sub> absorption equilibrium can be shifted
by removing one of the reaction products, resulting in a higher absorption
capacity. Two phase-change solvents are investigated: promoted potassium
carbonate (where the CO<sub>2</sub> is incorporated in the solid phase)
and potassium taurate (where the CO<sub>2</sub> is incorporated in
the liquid phase). A high-level assessment is performed with the two
phase-change solvents in order to identify key areas in solvent system
design for possible cost reduction. The impacts of absorption contactor
type, the addition of a solid–liquid separator, and heat integration
opportunities on capture cost and total heat duty are investigated.
For both phase-change solvents, the lowest capture cost is found when
the CO<sub>2</sub> absorption is operated in a packed column and advanced
heat exchanger integration is used in which the dissolution heat exchanger
duty is supplied without consuming low pressure (LP) steam for the
power plant. For the cases investigated, there is little difference
in capture cost between the two phase-change solvents
Reducing the Cost of CO<sub>2</sub> Capture from Flue Gases Using Aqueous Chemical Absorption
No full textChemical absorption is widely regarded
as the most promising technology
for CO2 capture from large industrial sources in the short
term. The cost of CO2 capture from postcombustion power
plants using monoethanolamine (MEA), the benchmark for chemical absorption,
is currently over US62–80 per metric ton
of CO2, with the most likely cost of US44–59
per metric ton of CO2, with the most likely cost of US$52
per metric ton of CO2 avoided, if the flue gas desulfurization
(FGD) and selective catalytic reduction (SCR) units can be eliminated
