Experimental and process simulation of hydrate-based CO2 capture from biogas

Qi, Li; Fan, Shuanshi; Chen, Qiuxiong; Yang, Guang; Chen, Yunwen; Li, Luling; Li, Gang

doi:10.1016/j.jngse.2019.103008

Cited by 35 publications

(24 citation statements)

References 31 publications

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“…Clearly, understanding the formation process of this clathrate is fundamental to the engineering and scientific community. As such, CO 2 hydrates have been studied extensively recently. − …”

Section: Introductionmentioning

confidence: 99%

Molecular Understanding of Homogeneous Nucleation of CO₂ Hydrates Using Transition Path Sampling

Arjun

Bolhuis

2020

J. Phys. Chem. B

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Carbon dioxide hydrate is a solid built from hydrogen-bond stabilized water cages that encapsulate individual CO 2 molecules. As potential candidates for reducing greenhouse gases, hydrates have attracted attention from both the industry and scientific community. Under high pressure and low temperature, hydrates are formed spontaneously from a mixture of CO 2 and water via nucleation and growth. Yet, for moderate undercooling, i.e., moderate supersaturation, studying hydrate formation with molecular simulations is very challenging due to the high nucleation barriers involved. We investigate the homogeneous nucleation mechanism of CO 2 hydrate as a function of temperature using transition path sampling (TPS), which generates ensembles of unbiased dynamical trajectories across the high barrier between the liquid and solid states. The resulting path ensembles reveal that at high driving force (low temperature), amorphous structures are predominantly formed, with 4 1 5 10 6 2 cages being the most abundant. With increasing temperature, the nucleation mechanism changes, and 5 12 6 2 becomes the most abundant cage type, giving rise to the crystalline sI structure. Reaction coordinate analysis can reveal the most important collective variable involved in the mechanism. With increasing temperature, we observe a shift from a single feature (size of the nucleus) to a 2-dimensional (size and cage type) variable as the salient ingredient of the reaction coordinate, and then back to only the nucleus size. This finding is in line with the underlying shift from an amorphous to a crystalline nucleation channel. Modeling such complex phase transformations using transition path sampling gives unbiased insight into the molecular mechanisms toward different polymorphs, and how these are determined by thermodynamics and kinetics. This study will be beneficial for researchers aiming to produce such hydrates with different polymorphic forms.

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Section: Introductionmentioning

confidence: 99%

Molecular Understanding of Homogeneous Nucleation of CO₂ Hydrates Using Transition Path Sampling

Arjun

Bolhuis

2020

J. Phys. Chem. B

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“…However, the weakly selective gas can also form hydrates, resulting in the lower selectivity of hydrate-based gas separation (HBGS) . In addition, HBGS requires separation operations at higher pressures, while some studies , have indicated that the compression energy consumption accounts for more than 50% of the total technological energy. Therefore, more in-depth research is needed to improve the mild experimental condition and separation selectivity.…”

Section: Introductionmentioning

confidence: 99%

Hydrate-Based Mild Separation of Lean-CH₄/CO₂ Binary Gas at Constant Pressure

Fan

Huang

et al. 2021

Energy Fuels

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The product gas of natural gas hydrate production by CO2 replacement is the lean-CH4/CO2 binary gas which contains 85–95% CO2. In this work, the lean-CH4/CO2 (10 mol % CH4/90 mol % CO2) binary mixture was used to simulate the product gas of natural gas hydrate production via CO2 replacement, and a promising and mild (low pressure) hydrate-based gas separation (HBGS) technology was employed. This work innovatively proposes to inject the reaction liquid to maintain the constant pressure of the whole process, which makes hydrates form continuously to increase the gas consumption. First, the hydrate phase equilibrium of 10 mol % CH4/90 mol % CO2 + 5 wt % tetrabutylammonium bromide (TBAB, aq) was measured in the range of 280–287 K and 0.5–4 MPa. After that, hydrate-based mild separation of the lean-CH4/CO2 binary gas was conducted with the help of TBAB at a constant pressure in the range of 1–4 MPa. The results show that after HBGS in addition with 5 wt % TBAB(aq) at 1 MPa and 278 K, the CH4 concentration could be increased from 17.2 to 66.2 mol % under constant pressure operation, while it was just slightly increased to 17.2 mol % under nonconstant pressure operation. HBGS with 5 wt % TBAB under constant pressure had the best separation performance. Subcooling has a greater effect on the separation kinetics. HBGS of 10 mol % CH4/90 mol % CO2 under a constant pressure operation of 2 MPa, subcooling of 6 K, and 5 wt % TBAB has the highest separation factor above 37. It is suggested that hydrate-based lean-CH4/CO2 separation experiments are carried out at a mild pressure with low G/L and, more importantly, in a short time. This work proposed a mild HBGS of lean-CH4/CO2 separation, which could benefit the separation of gas produced by natural gas hydrate replacement exploitation. This work also simultaneously provides insights into other HBGS for other gas mixtures (flue gas, coalbed methane, biogas, and shift gas) to achieve low energy consumption, high gas consumption, and high efficiency.

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“…Liu et al 19 studied shale gas CO 2 decarbonation process using [C 4 Mim][NTf 2 ], and the result indicated that the IL-based process can reduce over 42.8% of energy consumption. Li et al 20 simulated a biogas upgrading process using 5.0 wt % tetra-n-butylammonium bromide (TBAB), and the result illustrated that compared with the chemical absorption process, the energy consumption of their new upgrading process was 0.357 kW h/kg of biogas which was below that of chemical absorption process (0.582 kW h/kg of biogas) at CH 4 concentration from 67.00 to 97.00 mol %. Wang et al 21 modeled and simulated the process of CO 2 capture from flue gas using choline chloride/urea (1:2) deep eutectic solvent.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Several operational parameters are optimized for the ammoniacontaining tail gas purification process, such as the number of total theoretical stage (N stage ), feed stage of semilean liquid (N solvent ), the ratio of splitted lean liquid to the total liquid flow rate (R SLT ), total absorbent flow ratio (F total ), absorption pressure (P ab ), pressure of flash 1 (P flash1 ), pressure of flash 2 (P flash2 ), and temperature of flash 1 (T flash2 ). The value ranges are [6,20] for N stage , [4,18] for N solvent , [0.2, 0.8] for R SLT , [5,40] The optimization of the purification process is shown in the following equation. The objective functions are the minimum of TPC and TPCOE and maximum of η eff .…”

mentioning

confidence: 99%

Process Simulation and Optimization of Ammonia-Containing Gas Separation and Ammonia Recovery with Ionic Liquids

Zhan

Cao

Bai

et al. 2020

ACS Sustainable Chem. Eng.

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Ionic liquids (ILs) have been experimentally proved to be effective for ammonia-containing gas separation and recovery. A systematic strategy including thermodynamic models, process simulation, multiobjective genetic algorithm, and assessment for novel IL-based separation of ammonia-containing tail gas and ammonia recovery process was proposed. The conventional IL ([C4Mim][NTf2]) and the functional IL ([C4im][NTf2]) were selected, and their NH3 removal performance was investigated. Physical properties of models of IL systems were established with temperature-dependent equations, and gas–liquid phase equilibria of the NH3-IL system were molded with the nonrandom two liquid model equation. Total purification cost (TPC), total process CO2 emission (TPCOE), and thermodynamic efficiency (ηeff) were selected as the objective functions to be optimized. Process simulation results indicated that under same operational parameters, using functional ILs results in lower NH3 concentration in purified gas and higher removal efficiency than that of conventional ILs. After optimization, a series of solutions satisfying the constraints was provided by the Pareto front. The lowest objective functions can achieve 0.0211 $/N m3 (TPC), 265.67 kg CO2/h (TPCOE), and 48.05% (ηeff). Moreover, using functional ILs could greatly decrease purification cost and energy consumption and avoid wastewater discharge, which is an inevitable environmental problem in the water scrubbing process.

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Experimental and process simulation of hydrate-based CO2 capture from biogas

Cited by 35 publications

References 31 publications

Molecular Understanding of Homogeneous Nucleation of CO₂ Hydrates Using Transition Path Sampling

Molecular Understanding of Homogeneous Nucleation of CO₂ Hydrates Using Transition Path Sampling

Hydrate-Based Mild Separation of Lean-CH₄/CO₂ Binary Gas at Constant Pressure

Process Simulation and Optimization of Ammonia-Containing Gas Separation and Ammonia Recovery with Ionic Liquids

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Experimental and process simulation of hydrate-based CO2 capture from biogas

Cited by 35 publications

References 31 publications

Molecular Understanding of Homogeneous Nucleation of CO2 Hydrates Using Transition Path Sampling

Molecular Understanding of Homogeneous Nucleation of CO2 Hydrates Using Transition Path Sampling

Hydrate-Based Mild Separation of Lean-CH4/CO2 Binary Gas at Constant Pressure

Process Simulation and Optimization of Ammonia-Containing Gas Separation and Ammonia Recovery with Ionic Liquids

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Molecular Understanding of Homogeneous Nucleation of CO₂ Hydrates Using Transition Path Sampling

Molecular Understanding of Homogeneous Nucleation of CO₂ Hydrates Using Transition Path Sampling

Hydrate-Based Mild Separation of Lean-CH₄/CO₂ Binary Gas at Constant Pressure