Energy Consumption For Regeneration Research Articles

Composite Sorbents for CO2 Capture Based on Polyethyleneimine and Silica Gel: Study of Sorption Properties and Analysis of Thermal Energy Consumption

Studies of CO2 sorption by composite sorbents containing the active component (branched polyethylenimine) dispersed in the pores of mesoporous support (silica gel) have been carried out. It is shown that as silica gel pores are filled with polyethylenimine, the sorption efficiency of CO2 by the active component decreases, and the dynamic sorption capacity per 1 g of material passes through a maximum. The enthalpy values of CO2 sorption by composite sorbents have been determined. It is shown that the enthalpy values of CO2 sorption depend on the proportion of pore filling by the active component and on the characteristics of the porous structure of the support. Thermal energy consumption for regeneration of composite sorbents within the adsorption cycle was analyzed.

Novel DETA-Isobutanol biphasic solvent for post-combustion CO2 capture: High cyclic capacity and low energy consumption

In recent years, research into biphasic solvents has become an important direction more efficient control of CO2 emissions. However, most biphasic absorbents still face challenges such as low cyclic capacity and high viscosity of the rich phase. To develop a novel solvent with enhanced cyclic capacity and reduced regeneration energy consumption, a biphasic solvent consisting of DETA/Isobutanol/H2O was proposed. The results demonstrate excellent absorption and desorption performance of the DETA/Isobutanol/H2O biphasic solvent, with an absorption capacity ranging from 1.13 to 1.35 mol/mol and a cyclic capacity ranging from 0.61 to 0.84 mol/mol. After conducting 5 times absorption-desorption experiments, the cyclic capacity of DETA/Isobutanol/H2O biphasic solvent remained at 0.8 mol/mol. The estimated energy consumption for regeneration, under lean phase load, was calculated to be 2.42 GJ/t CO2, which was 42.24 % lower than that of 30wt% MEA aqueous solution (4.19 GJ/t CO2). The DETA/Isobutanol/H2O solution exhibits promising potential in terms of absorption-desorption performance and regenerative energy consumption, making it an exceptional CO2 absorbent.

N-doped carbon sphere-SiO2 composite structure materials with high adsorption rate and low regeneration energy consumption for CO2 capture from flue gas

N-doped carbon sphere-SiO2 composite structure materials with high adsorption rate and low regeneration energy consumption for CO2 capture from flue gas

Integrated CO2 absorption-mineralization process by the MEA + MDEA system coupled with Ba(OH)2: Absorption kinetics and mechanisms

In order to address the problems of poor performance of a single amine solvent in CO2 absorption and high regeneration energy consumption for thermal desorption, an integrated process was proposed in this study for CO2 absorption and mineralization using MEA + MDEA mixed amines coupled with Ba(OH)2 to produce high value-added BaCO3. The results showed that the optimal CO2 absorption performance was achieved with the use of 5 wt% of MEA and 2 wt% of MDEA. The Arrhenius activation energy Ea was 1.63 × 104 kJ/kmol, and the interaction coefficient β between MEA and MDEA reached up to 0.5, which had a positive effect on the absorption kinetics. The density functional theory (DFT) confirmed the reaction between the electron-donating group (−R3N¨) of MDEA and the strong electron withdrawing H+ of MEAH+, which contributed to the synergistic absorption mechanism involving proton transfer and formation of new bonds. The BaCO3 synthesized under conditions of 40 ℃, 60 min, and Ba(OH)2 addition ratio of 1: 1 was sphere-like and had a particle size of 150–200 nm and a specific surface area of 6.4430 m2/g, which aligned with the industry standard (1.5–15 m2/g) for opto-electronic level BaCO3. The FTIR spectra elucidated the CO2 absorption-mineralization mechanism that Ba(OH)2 could mineralize carbamate, CO32–/HCO3– and simultaneously regenerate free amine. The chemically regenerated MEA + MDEA solution performed stably in cyclic CO2 absorption and mineralization. This research sheds light on carbon emission reduction and CO2 resource utilization.

Investigating the Impact of Electrochemical Active Surface Area of Cu with Surfactant-Modified Carbon on Electrochemical CO2 Reduction in Acidic Electrolyte

Electrochemical CO2 reduction reaction (CO2RR) offers a promising avenue for transforming CO2 into valuable products, which can enable sustainable carbon utilization when powered by renewable energy sources. Traditionally, neutral or alkaline electrolytes are used in CO2RR to prevent hydrogen evolution reaction (HER). Employing such electrolytes, however, poses challenges due to homogeneous equilibrium reactions, leading to limiting CO2 availability and high energy consumption for electrolyte regeneration. Lowering electrolyte pH can address this issue and mitigate the required energy, resulting in industrially relevant efficiencies. Recent studies demonstrated encouraging results for CO2RR in acidic environments using flow cells. However, it remains unclear how conventional electrocatalysts perform under acidic conditions compared to neutral or alkaline ones. In addition, it is uncertain whether previous knowledge can be applied to acidic electrolytes in the same manner from neutral and alkaline conditions. Thus, in this study, we aim to evaluate the influence of surfactant-modified synthesis methods on the electrochemical active surface area (ECSA) of Cu and CO2RR performance in an acidic electrolyte.Different types of surfactants were employed to synthesize size-modulated Cu nanoparticles (NPs) on carbon black. Specifically, cetyltrimethylammonium bromide (CTAB), sodium dodecyl sulfate (SDS), and Triton X-100 represented cationic, anionic, and nonionic surfactants, respectively. Synthesis without surfactant treatment was further performed to elucidate surfactant-driven effects. Interestingly, variations in the size and distribution profiles of Cu NPs on carbon black were observed due to two roles of surfactant used in the synthesis: surface charge modifier and capping agent. In addition, the ECSA of Cu depended on the size and distribution of Cu NPs, highlighting the importance of both small size and uniform distribution to maximize ECSA. Finally, CO2RR activity was measured in a lab-made flow cell using 0.1 M H2SO4 with 0.4 M K2SO4. It was observed that large ECSA was beneficial to promoting CO2RR over HER with selective production of C2H4 over CH4 while the intrinsic activity of Cu itself was maintained. It was additionally reported that the selectivity of C2H4 over CH4 in the acidic electrolyte was more than 5 times higher than that in a neutral electrolyte, emphasizing the importance of the use of acid for CO2RR. Overall, this work provides critical electrocatalyst design criteria for efficient C2H4 production under acidic environments.

Effect of sterically hindered amines on the cycling capacity of biphasic absorbents for industrial CO2 capture

The biphasic solvent is a promising solution to reduce regeneration energy consumption in CO2 capture. However, most current biphasic solvents suffer from high viscosity and poor desorption of the rich phase. To the issues, a novel pentamethyldiethylenetriamine (PMDETA)-2-amino-2-methyl-1-propanol (AMP)/diethylenetriamine (DETA)-sulfolane biphasic solvent was developed. The mechanism of AMP affecting CO2 recycling capacity was analyzed. By adjusting the ratio of AMP and DETA, the absorption and desorption performance were balanced, and the recycling capacity and renewable energy consumption of the absorbent were improved. For the P2.4A0.8D0.8S2 biphasic solvent, the CO2 loading of the rich phase was 5.87 mol/L, and the proportion of the rich phase volume ratio was 35%, which surpasses most reported biphasic solvents. The viscosity of the absorbent significantly decreased from 527.00 mPa·s to 92.26 mPa·s, attributed to the beneficial effect of AMP. Thermodynamic analysis showed that the biphasic solvent produced a lower regeneration energy consumption of 1.70 GJ/t CO2, which was 57% lower than that of monoethanolamine (MEA). Overall, the PMDETA-AMP/DETA-sulfolane biphasic solvent exhibited cycle capacity, which provided new insights for the designing of biphasic solvent.

New insights into the functional group influence on CO2 absorption heat and CO2 equilibrium solubility by piperazine derivatives

Piperazine (PZ) derivatives which have been widely used in CO2 capture technology exhibit stable physicochemical properties, such as resistance to thermal degradation and low regeneration energy consumption. Both two parameters of CO2 absorbents, low CO2 absorption heat (ΔHabs) and large CO2 equilibrium solubility (αe), are important to CO2 capture performance. However, the influence of functional group types of PZ derivatives on their CO2 capture performance remained unclear. This research aimed to study the functional group influence on the ΔHabs and αe by PZ derivatives with two amines using experimental and quantum chemical methods. The results indicated that PZ derivatives with the ethyl side chain had larger ΔHabs and αe than those with the methyl side chain. The presence of the hydroxy group in PZ derivatives reduced the ΔHabs and the αe. The presence of cyclic methyl side chains on the N atom of PZ derivatives decreased the ΔHabs and increased αe at the same time. The findings show that PZ derivatives with cyclic methyl side chains, steric hindrance effect, and no hydroxy group are favorable for CO2 capture. Among the eight PZ derivatives, TEDA with lower ΔHabs (48.99 kJ/mol) and higher αe (0.917 mol CO2/mol amine) is an excellent absorbent. The results of this study are very important for screening efficient and low-energy consumption absorbents for CO2 capture.

Dual-bonded polyethyleneimine network with electron-withdrawing groups at α, β-sites for ultra-stable and low-energy CO2 capture in harsh environments

As an innovative approach to addressing climate change, significant efforts have been dedicated to the development of amine sorbents for CO2 capture. However, the high energy requirements and limited lifespan of these sorbents, such as oxidative and water stability, pose significant challenges to their widespread commercial adoption. Moreover, the understanding of the relationship between adsorption energy and adsorption sites is not known. In this work, a dual-bond strategy was used to create novel secondary amine structures by a polyethyleneimine (PEI) network with electron-extracted (EE) amine sites at adjacent sites, thereby weakening the CO2 binding energy while maintaining the binding ability. In-situ FT-IR and DFT demonstrated the oxygen-containing functional groups adjacent to the amino group withdraw electrons from the N atom, thereby reducing the CO2 adsorption capacity of the secondary amine, resulting in lower regeneration energy consumption of 1.39 GJ t−1-CO2. In addition, the EE sorbents demonstrated remarkable performance with retention of over 90 % of their working capacity after 100 cycles, even under harsh conditions containing 10 % O2 and 20 % H2O. DFT calculations were employed to clarify for the first time the mechanism that the oxygen functional group at the α-site hinders the formation of the urea structure, thereby being an antioxidant. These findings highlight the promising potential of such sorbents for deployment in various CO2 emission scenarios, irrespective of environmental conditions.

Enhanced SO2 and CO2 synergistic capture with reduced NH3 emissions using multi-stage solvent circulation process

NH3-based SO2 and CO2 synergistic capture technology shows promise in reducing the costs associated with current flue gas desulfurization and CO2 capture systems. However, it faces challenges such as NH3 slip and high energy consumption. In this study, we proposed an advanced Multi-Stage Solvent Circulation (MSC) process that incorporates a desulfurization-washing solution circulation, which involved partitioned absorption according to different functions of SO2 capture, CO2 capture, and NH3 emission control. The experimental results demonstrated that using desulfurization solution in place of water for washing reduced the NH3 emissions from the absorber and desorber by 10.6 % and 7.9 %, respectively. Additionally, the recovered NH3 enhanced SO2 capture, resulting in a 61.8 % decrease in SO2 emission concentration. A pilot-plant trial model for SO2 and CO2 synergistic capture was further developed using Aspen Plus. The impact of operational time and parameters on capture efficiency and energy consumption were analyzed. Under typical flue gas conditions, the process achieved SO2 capture efficiency of > 99 %, regeneration energy consumption of 2.42 GJ/t CO2, NH3 emissions of < 5 ppm. This study presents a novel approach for designing a SO2 and CO2 synergistic capture system, which has the potential to facilitate the economic and effective implementation of post-combustion flue gas pollutant control management and carbon emission reduction.

Comparison of liquid–liquid phase equilibrium behavior of acetonitrile–water system using choline chloride salt and water-based deep eutectic solvent

The liquid–liquid equilibrium (LLE) data for the ternary systems of (acetonitrile (ACN) + water (W) + choline chloride (ChCl)) and (ACN + W + water-based deep eutectic solvent (WDES) consisting of ChCl:W (1:3)) were measured at 298 K. The consistency of tie-lines was verified by the Bachman and Othmer–Tobias correlations. ChCl as an organic salt and its WDES (within the water content range of less than 50 w%) as green extractants represent feasible performances in terms of selectivity and distribution coefficients for separation of water from acetonitrile-water system in comparison to other inorganic salts and hydrophobic DESs. ChCl in the (ACN + W + ChCl) system can separate water from the solution in the form of hydrate ions while WDES in the (ACN + W + WDES) system tends to absorb water by intermolecular forces. The experimental data of the (ACN + W + ChCl) system was correlated using the symmetric electrolyte non-random two liquid (e-NRTL) model while the equilibrium data of the (ACN + W + WDES) system was correlated using NRTL and universal quasi-chemical activity coefficient (UNIQUAC) models. ChCl in the form of salt represents a better separation performance than WDES for water removal from the acetonitrile mixture. Meanwhile, WDES might be considered to be superior compared to ChCl in terms of regeneration energy consumption and operating considerations.

Ethyl levulinate regulates traditional sulfolane biphasic absorbent for energy-efficient CO2 capture

Traditional CO2 biphasic absorbents currently suffer from problems such as high initial phase separation loading, poor product distribution selectivity, and weak dynamic phase separation ability, which limit their potential for industrial applications. This study developed a biphasic absorbent regulated by dual physical solvents by introducing partial ethyl levulinate (EL) into a sulfolane biphasic system. The optimal composition of this system was 30 wt% 1-amino-2-propanol (MIPA), 20 wt% sulfolane and 30 wt% EL. Under dual physical solvent conditions, strong electrostatic attraction between MIPA and CO2 promoted generation of MIPA zwitterions and carbamate. Analysis of the interactions between different product components through electrostatic potentials and with an independent gradient model based on Hirshfeld's partitioning revealed only extremely weak van der Waals force-driven interactions between the reaction products and EL. These interactions substantially reduced the initial phase separation loading and offered precise control over phase transition behavior. Compared with MIPA/sulfolane system, the MIPA/sulfolane/EL system achieved a 48.9 % lower initial phase separation loading, an 11.6 % lower proportion of saturated rich phase volume, a 10.1 % higher CO2-rich phase loading, and a 6.7 % lower viscosity. The excellent dynamic phase separation performance was verified using a customized device and the energy consumption for CO2 regeneration decreased to 2.2 GJ/t CO2.

Investigation on CO2 capture performance of low-viscosity diamine non-aqueous absorbents with N-methyldiethanolamine regulation

In recent years, non-aqueous absorbents have attracted increasing attention due to their ability of significantly reducing sensible and latent heats in regeneration processes compared to conventional organic amine aqueous solution. But high viscosity of non-aqueous absorbents after CO2 absorption saturation became an obstacle to their industrial application. Here, a novel low-viscosity diamine non-aqueous absorbent for high-efficiency CO2 capture was proposed, in which N-methyldiethanolamine (MDEA) with steric hindrance effect was introduced as a regulator and dimethyl sulfoxide (DMSO) as a cosolvent. The effects of MDEA on CO2 capture performance of various non-aqueous absorbents and its regulation mechanism on CO2 absorbent viscosity were investigated systematically. Experimental results showed that when 25 wt% 2-(2-aminoethylamino)ethanol (AEEA) was screened as main CO2 absorption component, AEEA/MDEA/DMSO non-aqueous absorbent exhibited a high CO2 absorption capacity of 2.55 mol/kg and a fast CO2 absorption rate. Based on further mass fraction optimisation, it was found that the lowest viscosity of non-aqueous absorbents after CO2 absorption was 13.12 mPa s and the highest CO2 regeneration reached 93.5 % with AEEA and MDEA were 17.5 wt% and 12.5 wt%, respectively. 13C NMR tests showed that two characteristic peaks of carboxylated carbon appeared in CO2 products, which indicated that both amino groups on AEEA molecule were involved in CO2 absorption reaction. DFT calculations indicated that hydrogen bonding strength between MDEA and CO2 products was relatively lower than that of AEEA and CO2 products, which favored reducing absorbent saturation viscosity significantly. Thermodynamic analysis revealed that total regeneration energy consumption for 17.5 wt% AEEA/12.5 wt% MDEA/70 wt% DMSO non-aqueous absorbent was 1.72 GJ/t CO2, which was 53 % lower than that of MEA aqueous solution.

Simulation and optimization for flue gas CO2 capture by energy efficient water-lean ionic liquid solvent

Ionic liquids (IL) are treated as advanced materials for energy-saving carbon dioxide (CO2) capture from flue gas but suffer from serious challenges in energy and mass management. Herein, a water-lean IL-based deep eutectic solvent with 1,8-diazabicyclo [5.4.0] undec-7-ene imidazole ([DBU] [IM]) and ethylene glycol (EG) blends was prepared with a screened proportion of IL:EG=7:3. The CO2 loading and saturated solvent viscosity were 1.89 mol/L and 95 mPa·s, respectively. The foundational properties of the IL-EG solvent were determined by experimental measurements and thermodynamic modeling. The vacuum flashing desorption technology was innovatively adopted for energy-saving solvent regeneration. Industrial-scale process simulation of multistage flashing was used to explore the energy consumption during solvent regeneration. Meanwhile, the segmented cooling paved a route for water separation from water-lean solvent. A comprehensive analysis was performed out to optimize the operating parameters for CO2 absorption and desorption. For the recommended 3-stage flashing configuration, the specific process regeneration energy consumption amounted to only 1.54 GJ/tCO2. Consequently, the total capture cost reduced to 48.1 $/tCO2, marking a decrease of 31.28 %, 16.55 % and 10.25 %, compared with MEA solvent, water-lean solvent and biphasic solvent, respectively. This work offered insights for future endeavors in the development of IL-based CO2 capture process from industrial flue gas.

Systematic experiment on adsorption, separation and regeneration of X zeolites for LNG production with different regeneration strategies: vacuum, purging, heating and hybrid combinations

This work experimentally investigated the adsorption, separation and regeneration properties of two X zeolites for natural gas deep decarbonization in liquified natural gas (LNG) production. The regeneration properties of JLOX500 and 13X were compared with relation to regeneration efficiency, energy consumption, desorption and adsorption rate of CO2, and other factors in different pathways: vacuum, purging, heating, and hybrid combinations. The results demonstrated that fresh JLOX500 with more cations and less binders had significantly greater CO2 adsorption capacities and larger separation factor (CO2/CH4) than those of fresh 13X, because of its larger micro-porosity and higher CO2 isosteric heat. Due to higher partial pressure, the adversely significant effect of CH4 competing adsorption against CO2 on adsorbent regeneration is confirmed. The flow rate increases of purge gas had no effects on regeneration efficiency for 13X when the CO2 concentration of desorbed gas reached to zero. Because of a greater cumulative pore volume, JLOX500 after sufficient regeneration has a larger CO2 adsorption capacity and a higher desorption rate of CO2 than 13X, which also makes it more efficient with regards to purge gas and energy consumption utilization. With 150 mL/min of purge gas, the energy consumptions for 13X and JLOX500 regenerated at 150 °C were 4.20 and 2.89 MJ/kg-CO2, respectively. The CH4 recovery relied on the regeneration efficiency of adsorbents, duration of adsorption, and the amount of purge gas used. Both X zeolites regenerated by purging (150 mL/min) or vacuuming at 1 kPa at 150°C could purify the feed to the CO2 content less than 50 ppm, but JLOX500 is more efficient with regards to the overall performance.

Study of ship-based carbon capture optimization considering multiple evaluation factors and main engine loads

Ship-Based Carbon Capture (SBCC) technology presents a promising approach to reduce greenhouse gas emissions in the marine transportation. Solvent-based carbon capture has emerged as a leading technology for SBCC, primarily due to its low retrofit costs and effectiveness in treating flue gas with low carbon content. However, challenges remain in optimizing system operation efficiency under the variable conditions of ship main engine loads and in understanding the mechanisms by which process parameters influence key evaluation factors. Consequently, this study established a pilot-scale experimental platform for solvent-based SBCC and developed a carbon capture model based on it. The influence of process parameters, such as main engine exhaust flow rate and liquid/gas ratio (L/G), on the evaluation factors was thoroughly explored. With the utilization of Shapley Additive Explanations (SHAP) analysis to quantify the influence of process parameters on the evaluation factors, a multi-objective optimization equation is proposed. The combination of machine learning and optimization algorithms offers an efficient approach for determining the optimal process of the SBCC system under different main engine loads. The research results show that the main engine exhaust flow rate is the most important process parameter affecting the carbon capture rate (CR), with an influence ratio as high as 64.33%. As the main engine exhaust flow rate increases, the maximum CR decreases from 97.84% to 61.13%. Although the extreme value of the regeneration energy consumption (REC) also decreases from 6.66 to 4.42 GJ/t CO2, the solvent flow rate's influence on REC is also significant, with influence ratios of 38.49% and 35.53%, respectively. A data-driven approach examined the optimal operating conditions at eight main engine loads, achieving a carbon capture rate prediction error of only 1.42% and a maximum REC error of only 0.55 GJ/t CO2. This study provides essential guidance for assessing the suitability of SBCC systems.

Dihydroxyl-Cooperative 1,2,4-Triazole-Based Ionic Liquid for Robust Reversible CO2 Absorption.

The development of aqueous absorbents for CO2 capture is significantly important to reduce global industrial gas emissions through high regeneration efficiency and low energy consumption. Herein, we newly designed and prepared a dihydroxylated ionic liquid (IL) bis(2-hydroxyethyl)dimethylammonium 1,2,4-triazole ([N1,1,2OH,2OH][TZ]) for highly efficient CO2 absorption through anion-cation cooperative interactions. A superior capacity of 1.33 mol of CO2 per mol of IL and excellent reversibility have been achieved by the introduction of dihydroxy sites on the ammonium-based Tz IL. 1H and 13C nuclear magnetic resonance, Fourier transform infrared, and quantum chemical calculations demonstrate bihydroxyl-cooperative absorption of CO2 via hydrogen bond interaction between the cation and anion of the IL. The theory calculation shows that IL displays a superlow reactive absorption enthalpy, favorable to the reversible CO2 absorption, which can maintain an initial absorption capacity of 98.5% with the cycle numbers of 100, implying the facile regeneration and superlow energy consumption. Thus, the functionalized ILs toward group cooperative gas absorption and excellent reversibility may open a door to designing new materials for enhancing CO2 absorption and utilization.

Molecular simulation and experimental understanding of piperazine-promoted 2-cyclopentylaminoethanol for energy-efficient carbon capture

With the serious climate change and carbon emissions issues facing the world, it is becoming increasingly important to find effective methods to reduce the post-combustion CO2 concentrations. Piperazine −enhanced aqueous amine solvents are still being developed due to the technology is more applicable to large −scale industry. However, the sustainability of the CO2 capture process is still hindered by high energy consumption and amine losses. To tackle this issue, a novel secondary amine, 2-cyclopentylaminoethanol, was synthesized from a primary amine, monoethanolamine. It has a more stable structure than monoethanolamine and was further activated by piperazine. Its effectiveness was compared with piperazine-enhanced N-methyldiethanolamine, N-methyldiethanolamine/triethylenediamine, and 2-amino-2-methyl-1-propanol. The experimental results showed that 2-cyclopentylaminoethanol/piperazine presents the fastest CO2 mass transfer rate, the largest CO2 cyclic capacity and a lower latent heat. The regeneration energy consumption of the absorbent is approximately 2.44 GJ/ton CO2, which is approximately 37.45% lower than that of 30 wt% monoethanolamine solvent. The results are in accordance with the findings of a laboratory-scale pilot plant study, which demonstrated an average reduction of 35.3% in energy consumption. Molecular simulations have revealed that 2-cyclopentylaminoethanol exhibits the lowest energy barrier for reacting with CO2, rendering it more conducive to CO2 reaction. The intermolecular interactions indicate that the hydrogen bonding in the solution after monoethanolamine reacts with CO₂ becomes more pronounced, coupled with a higher energy barrier. Consequently, a greater amount of energy is required during desorption. It can be inferred that 2-cyclopentylaminoethanol/piperazine is a promising energy-efficient and stable absorbent for post-combustion CO2 capture.

Understanding the Catalytic Effect on the CO2 Regeneration Performance of Amine Aqueous Solutions

To address the high energy consumption of the carbon capture and storage process in the shipping industry, the effects of several commonly used commercial catalysts, such as HZSM-5-25, γ-Al2O3, and SiO2, as well as a self-prepared catalyst, Zr-HZSM-5-25, on the regeneration of MEA solution and MEA + MDEA mixed solution were investigated in this paper. The results showed that Zr-HZSM-5-25 had the best catalytic effect on the regeneration process of the MEA aqueous solution, which could increase the instantaneous maximum CO2 regeneration rate of the MEA-rich solution by about 8.25% and the average regeneration rate by about 5.28%. For the MEA + MDEA mixed solution, the reaction between tertiary amine MDEA and CO2 produced a large amount of HCO3− in the reaction system, which could accelerate the release of CO2 to a large extent, which resulted in the catalytic effect of the Zr-HZSM-5-25 catalyst on the regeneration process of the mixed amine solution being significantly lower than that on the single MEA solution, with an increase of 4.91% in the instantaneous maximum regeneration rate. This instantaneous maximum regeneration rate was only increased by 4.91%. While Zr-HZSM-5-25 showed a better performance in the bench-scale test, it reduced CO2 regeneration energy consumption by 7.3%.

Synthesis of desulfurization solvent networks based on process characteristics: New insights of desulfurization units and a novel synthesis method

Synthesis of desulfurization solvent network (DSN) can reduce the solvent circulation and the energy consumption for solvent regeneration. Based on the desulfurization process characteristics, this work proposes a novel graphic to explore the operating limitations of a desulfurization unit. A feasible operating window of the desulfurization unit is presented with three boundary lines to constrain the solvent reuse. Different cases for the solvent reuse between units are analyzed in details, and two rules for rich solvent reuse are proposed and proven. A novel hierarchical method is developed for the DSN synthesis. A refinery case is investigated using the proposed method. Four DSN designs are obtained, and the fresh solvent consumption can be reduced by 13.7 %. The accuracy of the four designs is verified by rigorous simulation, showing a maximum relative error of 1.22 %. The proposed method can show clear insights in DSN synthesis and give reliable and concise designs.

Energy consumption optimization of CO2 capture and compression in natural gas combined cycle power plant through configuration modification and process integration

Currently, natural gas combined cycle (NGCC) power plants account for a quarter of global electricity power supply and lead to greenhouse gas emissions. Carbon capture and storage (CCS) is one of the most effective technologies to reduce carbon emissions in the short term. However, the monoethanolamine (MEA)-based CO2 absorption and compression process is energy-intensive, which significantly reduces the power generation efficiency of NGCC. In addition, the waste hot and cold energy from NGCC and liquefied natural gas (LNG) regasification process, which are generally wasted, can be recovered for the CCS process. Therefore, this study aims to reduce the energy consumption of the carbon capture process and recover waste LNG cold energy and hot energy in the NGCC through configuration modification and process integration. The results show that the energy consumption of CO2 regeneration in the proposed CO2 capture process configuration is reduced by 18.03 %, and the net power efficiency of the NGCC plant increases from 48.88 % to 50.10 %. Furthermore, a cascade two-stage organic Rankine cycle is integrated into the system for waste heat recovery, which can generate 5.04 MW electric power and reduce the efficiency penalty of the plant from 13.72 % to 10.29 %. By contrast, the alternative application of LNG cold energy to the CO2 compression process reduces compression power by 3.95 MW with a lower footprint and utility requirement while the efficiency penalty is decreased by 3.15 %.