CAS Guangzhou Center for Gas Hydrate Research

Guangzhou, China

CAS Guangzhou Center for Gas Hydrate Research

Guangzhou, China
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Li X.-S.,CAS Guangzhou Institute of Energy Conversation | Li X.-S.,CAS Guangzhou Center for Gas Hydrate Research | Xu C.-G.,CAS Guangzhou Institute of Energy Conversation | Xu C.-G.,CAS Guangzhou Center for Gas Hydrate Research | And 5 more authors.
Energy | Year: 2011

Effects of 0.29mol% tetra-n-butyl ammonium bromide (TBAB) solution in conjunction with cyclopentane (CP) on the hydrate-based pre-combustion CO2 capture are investigated by the measurements of the gas uptakes, CO2 separation efficiencies and induction time of the hydrate formation at the different temperature-pressure conditions. The results show that the volume of the TBAB has an effect on the CO2 separation and the induction time, and the addition of the CP into the TBAB solution remarkably enhances the CO2 separation and shortens the induction time. The system with the CP/TBAB solution volume ratio of 5vol% and TBAB solution/reactor effective volume ratio of 0.54 is optimum to obtain the largest gas uptake and the highest CO2 separation efficiency at 274.65K and 4.0MPa. Compared to the results with tetrahydrofuran (THF) as an additive [1], the gas uptake is enhanced by at least 2 times and the induction time is shortened at least 10 times at the similar temperature-pressure condition. In addition, the CO2 concentration in the decomposed gas from the hydrate slurry phase reaches approximately 93mol% after the first-stage separation at 274.65K and 2.5MPa. The gas uptakes of more than 80mol% are obtained after 400s at the temperature range of 274.65-277.65K and the pressure range of 2.5-4.5MPa. © 2011 Elsevier Ltd.


Xu C.-G.,CAS Guangzhou Institute of Energy Conversation | Xu C.-G.,CAS Guangzhou Center for Gas Hydrate Research | Li X.-S.,CAS Guangzhou Institute of Energy Conversation | Li X.-S.,CAS Guangzhou Center for Gas Hydrate Research
RSC Advances | Year: 2014

Hydrate-based CO2 separation and capture from gas mixtures containing CO2 has gained growing attention as a new technology for gas separation, and it is of significance for reducing anthropogenic CO 2 emissions. Previous studies of the technology include the thermodynamics and kinetics of hydrate formation/dissociation, hydrate formation additives, analytical methods, separation and capture progress, equipment and applications. Presently, the technology is still in the experimental research stages, and there are few reports of industrial application. This review examines research progress in the hydrate formation process and analytical methods with a special focus on laboratory studies, including the knowledge developed in analog computation, laboratory experiments, and industrial simulation. By comparing the various studies, we propose original comments and suggestions on further developing hydrate-based CO2 separation and capture technology. © 2014 The Partner Organisations.


Xu C.-G.,CAS Guangzhou Institute of Energy Conversation | Xu C.-G.,CAS Guangzhou Center for Gas Hydrate Research | Chen Z.-Y.,CAS Guangzhou Institute of Energy Conversation | Chen Z.-Y.,CAS Guangzhou Center for Gas Hydrate Research | And 4 more authors.
Energy and Fuels | Year: 2014

Technology of hydrate-based CO2 separation and capture is considered as a green and economical gas separation technology and is extensively studied. Most of the previous studies involving the aspects of thermodynamics and kinetics of the CO2 gas hydrate formation were carried out with small reactors, whereas few studies were carried out with pilot-scale equipments. In this paper, a pilot-scale CO2 separation from flue gas by the hydrate method is reported. By the equipment, we successfully realize CO2 separation from flue gas. By a two-stage hydrate separation process, the CO2 concentration can be enhanced to approximately 90.0% from 17.0%. The effects of the operating pressure and gas flow rate on CO2 recovery are also investigated by comparing and analyzing the data of the CO2 concentration, gas consumption, and CO2 recovery. The higher pressure results in the higher CO 2 recovery, and there is an optimal ratio of the gas flow rate to the fluid flow rate for obtaining the highest gas consumption. The results achieved in this paper will be an important foundation to further develop the continuous CO2 hydrate separation process. © 2013 American Chemical Society.


Zhang Z.,Taiyuan University of Technology | Yan K.,CAS Guangzhou Institute of Energy Conversation | Yan K.,CAS Guangzhou Center for Gas Hydrate Research | Yan K.,University of Chinese Academy of Sciences | Zhang J.,Taiyuan University of Technology
RSC Advances | Year: 2013

In order to investigate the initiation mechanisms associated with the pyrolysis of triglyceride that could potentially be used as petrochemical replacements, we carried out 500 ps molecular dynamics simulations employing the ReaxFF reactive force field using tripalmitin as the model molecule at 1500 and 2000 K. We find that the primary decomposition reactions of tripalmitin initiate with the successive scission of the alkyl-oxygen bond to form three straight chain C16H31O2 (RCOO) radicals and C3H5 radical. The deoxygenated alkyl chain is produced through the decarboxylation of the RCOO radical with concurrent production of CO2. The resulting alkyl and C3H5 radicals further undergo recombination and decomposition to yield mainly alkanes and alkenes, with the actual product distribution being dependent on reaction temperature. β-Scission plays an important role in alkyl chain decomposition with a concomitant release of C2H4. Compared to 1500 K, this reaction is accelerated at 2000 K. In addition, the formation of cyclic hydrocarbon is also observed at 2000 K. As opposed to previous proposed Diels-Alder reactions or intramolecular cyclizations of alkenyl radicals mechanisms, it is found that cyclopentane could be produced by intramolecular cyclization of a biradical. © 2013 The Royal Society of Chemistry.


Xu C.-G.,CAS Guangzhou Institute of Energy Conversation | Xu C.-G.,CAS Guangzhou Center for Gas Hydrate Research | Zhang S.-H.,CAS Guangzhou Institute of Energy Conversation | Zhang S.-H.,CAS Guangzhou Center for Gas Hydrate Research | And 6 more authors.
Energy | Year: 2013

The hydrate-based CO2 (carbon dioxide) separation and capture from CO2/H2 (hydrogen) gas mixtures with the different CO2 concentrations is investigated in 0.29mol% TBAB (tetra-n-butyl ammonium bromide) solution. Raman spectroscopic analysis is employed to determine the compositions of the mixed hydrates containing CO2, H2, TBAB and H2O (water). The phase equilibrium conditions shift to extreme conditions as decreasing CO2 from 40.0% to 10.0% in the gas mixtures. At the temperature of 274.15K and under driving force of 3.0MPa, the hydrate formation induction time increases while the CO2 recovery (or separation fraction) decreases with the decrease of CO2. Raman peaks for CO2 gas shift to higher frequency side of 6-10cm-1 as the CO2 concentration turns from 40.0% to the range of 10.0-18.0%. Meanwhile, no Raman spectral signal is detected for H-H stretching vibration in the mixed hydrates. © 2013 Elsevier Ltd.


Li X.-S.,CAS Guangzhou Institute of Energy Conversation | Li X.-S.,CAS Guangzhou Center for Gas Hydrate Research | Yang B.,CAS Guangzhou Institute of Energy Conversation | Yang B.,CAS Guangzhou Center for Gas Hydrate Research | And 7 more authors.
Applied Energy | Year: 2013

A 117.8. L three-dimensional pressure vessel is used to study the methane hydrate dissociation with the steam assisted gravity drainage (SAGD) method. It is called the Pilot-Scale Hydrate Simulator (PHS). This study proposes the evaluation and the comparisons of the gas production performance by SAGD method from the methane hydrate reservoir with different steam injection rates. It indicates that the experiment could be divided into three main stages: the original gas releasing stage, the original and the hydrate-originating gas releasing stage, and the hydrate-originating gas releasing stage (the SAGD process). Furthermore, the temperature change consists of the four periods: decreasing dramatically, keeping stable, rising gradually, and keeping steady. With the injected steam flowing downwards and sideways, the steam chamber is expanding. The gas production rate increases with the steam injection rate, while the Energy Efficiency Ratio (EER) and gas-to-water ratios are improved by the decrease of the steam injection rate. © 2013 Elsevier Ltd.


Xu C.-G.,CAS Guangzhou Institute of Energy Conversation | Xu C.-G.,CAS Guangzhou Center for Gas Hydrate Research | Li X.-S.,CAS Guangzhou Institute of Energy Conversation | Li X.-S.,CAS Guangzhou Center for Gas Hydrate Research | And 6 more authors.
Energy | Year: 2012

The hydrate-based carbon dioxide (CO 2) capture from the integrated gasification combined cycle (IGCC) synthesis gas using the bubble method is investigated with a set of visual equipment in this work. The gas bubble is created with a bubble plate on the bottom of the equipment. By the visual equipment, the hydrate formation and the hydrate shape are visually captured. With the move of the gas bubble from the bottom to the top of the reactor, gas hydrate forms firstly from the gas-liquid boundary around the bubble, then the hydrate gradually grows up and piles up in the bottom side of the bubble to form a hydrate particle. The gas hydrate shape is affected by the gas flow rate. The hydrate is acicular crystal at the low gas flow rate while the hydrate is fine sand-like crystal at the high gas flow rate. The bubble size and the gas flow rate have an obvious impact on the hydrate-based CO 2 separation process. The experimental results show the gas bubble of 50 μm and the gas flow rate of 6.75 mL/min/L are ideal for CO 2 capture from IGCC synthesis gas under the condition of 3.0 MPa and 274.15 K. © 2012 Elsevier Ltd.


Peng X.,Beijing University of Chemical Technology | Peng X.,CAS Guangzhou Center for Gas Hydrate Research | Zhou J.,CAS Institute of High Energy Physics | Wang W.,Beijing University of Chemical Technology | Cao D.,Beijing University of Chemical Technology
Carbon | Year: 2010

We perform a molecular simulation study on methane and carbon dioxide storage in carbon nanoscrolls. The effects of temperature and pressure, interlayer spacing, VDW gap and innermost radius on the gas storage have been examined extensively. It is found that the adsorption of gases on pristine carbon nanoscrolls is relatively low. However, once the interlayer spacing is expanded, both adsorption capacities of methane and carbon dioxide exhibit a significant improvement. In particular, the excess uptake of methane reaches 13 mmol/g at p = 6.0 MPa and T = 298.15 K and VDW gap Δ = 1.1 nm, which is about 3.5 times of uptake of the pristine carbon nanoscrolls; while the uptake of carbon dioxide could also be raised by 294.9% at T = 298.15 K and p = 3.0 MPa and Δ = 1.5 nm, reaching 30.21 mmol/g at 6.0 MPa. This work demonstrates that carbon nanoscrolls with an expansion of interlayer spacing may be a suitable material for methane storage and carbon dioxide capture. © 2010 Elsevier Ltd. All rights reserved.


Li X.-S.,CAS Guangzhou Institute of Energy Conversation | Li X.-S.,CAS Guangzhou Center for Gas Hydrate Research | Xu C.-G.,CAS Guangzhou Institute of Energy Conversation | Xu C.-G.,CAS Guangzhou Center for Gas Hydrate Research | And 5 more authors.
Energy | Year: 2010

To determine the appropriate operating conditions for separating carbon dioxide from flue gas via the hydrate formation, the effects of the concentrations of dodecyl trimethyl ammonium chloride (DTAC) in 0.29mol% Tetra-n-butyl ammonium bromide (TBAB) aqueous solution and the initial pressures on the induction time of the hydrate formation and CO2 separation efficiency are investigated. The experiments are conducted at the DTAC concentration range of 0-0.056mol%, initial pressures range of 0.66MPa-2.66MPa and temperature range of 274.95K-277.15K. The results indicate that the initial pressure of 1.66MPa in conjunction with the concentration of 0.028mol% DTAC is most favorable for CO2 separation. At the condition, the induction time of forming the hydrate can be shortened considerably and CO2 can be purified from 17.0mol% to 99.4% with the two-stage hydrate separation process. CO2 split fractions for Stage 1 and Stage 2 are 0.54 and 0.39, respectively, and the separation factors are 9.60 and 62.25, respectively. © 2010.


Yan G.,Taiyuan University of Technology | Zhang Z.,Taiyuan University of Technology | Yan K.,CAS Guangzhou Institute of Energy Conversation | Yan K.,CAS Guangzhou Center for Gas Hydrate Research | Yan K.,University of Chinese Academy of Sciences
Molecular Physics | Year: 2013

To investigate the detailed mechanisms for brown coal oxidation at high temperatures, a ReaxFF reactive forcefield was used to perform a series of molecular dynamics simulations from 1000 K to 2500 K. Analyses indicated that the chemical system tend to be more reactive with increasing temperature. It was found that the oxidation process of brown coal primarily initiates from hydrogen abstraction reactions by O2 and related oxygenated radicals from phenolic hydroxyl groups, methyl groups, especially carboxyl groups in lower temperature to form peroxygen species, or by either thermal decomposition of brown coal backbone in higher temperature. These peroxygen species usually could chemically adsorb on the C-centered radicals of brown coal backbone. The weak O-O bond in peroxygen makes them easier to break into oxygenated radical, which could also chemically adsorb on the C-centred radical to form hydroxyl group and other oxygenated compounds. In the oxidation process of brown coal, the decomposition and oxidation of aliphatic chain is easier than aromatic ring. The chemisorption of peroxygen radical induces the breakage of aromatic ring and accelerates the depth oxidation of brown coal. An increasing number of products are observed with increasing temperature. © 2013 Taylor and Francis.

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