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Investigations of natural gas hydrate dissociation from a slurry to a water-in-oil emulsion are conducted in a high-pressure hydrate experimental flow loop equipped with on-line microcosmic instruments including a focused beam reflectance measurement (FBRM) probe and a particle video microscope (PVM) probe. Three stages of the dissociation processes are observed and sketched in a conceptual mechanistic...
The catalytic effect of calcium on the steam gasification of Shengli chars was studied in this work. The calcium-added chars were prepared by pyrolysis under argon atmosphere from calcium oxide added demineralized Shengli lignite. The chars were characterized in detail by SEM-EDX, XRD, Raman, FTIR and XPS and were tested on a fixed-bed reactor to evaluate its performances steam gasification. Calcium...
The water vapor and trace gas impurities play important roles on CO2 capture performance using porous materials. We investigated the effects of H2O, SO2, and O2 on CO2 capture in a series of ZIFs with same SOD topology but different functional groups, such as ZIF-8, ZIF-90, ZIF-Cl, ZIF-NO2, and SALEM-2 by grand canonical Monte Carlo simulations. The results show that H2O and SO2 show a cooperative...
Studies of spent coffee grounds (SCGs) as a potential biodiesel feedstock in recent years mostly started from solvent extraction to obtain coffee oil, and then converted it into coffee biodiesel in two steps, acid esterification followed by alkaline transesterification. This paper presents a direct transesterification (in situ) method that produces biodiesel from SCGs without the need for oil extraction...
Experiments of ignition delay times on 2,4,4-trimethyl-1-pentene were performed behind reflected shock waves at pressure ranging from 2atm to 10atm, at equivalence ratios from 0.5 to 2.0, and with fuel concentrations of 0.5%, 0.75% and 1%. All ignition delay times follow the Arrhenius rule, and discussions on the effect of pressure, temperature, equivalence ratio and fuel concentration on ignition...
Moderate or intense low-oxygen dilution (MILD) combustion has increasingly attracted the attention of scholars because of its high efficiency and low-pollutant emission, particularly its emission of CO and NOX. MILD combustion without preheated air was achieved in this study. Numerical results obtained by a computational fluid dynamics model with GRI-Mech 3.0 conform well to those from the experiments...
Ignition delay times of dimethoxy methane (DMM), n-heptane and DMM/n-heptane mixtures were measured behind reflected shock waves. The experiments were performed at the temperature ranges of 1100–1600K, at pressures of 2 and 10atm and equivalence ratios of 0.5, 1.0 and 2.0. A chemical kinetic model for DMM/n-heptane blends was built and validated with the experimental data. The calculations well agreed...
The efforts of supercritical water (SCW) on sulfur transformation during coal gasification process were studied in a batch autoclave. Sulfur morphological distribution of two different rank coals on solid, liquid and gas phase at different temperatures were thoroughly investigated during coal SCW gasification compared with coal pyrolysis. Compared with coal pyrolysis, the removal of sulfate-sulfur...
Removal of mercury from flue gas has been considered as one of the hot topics in both the scientific and industrial world. Adsorption of elemental mercury (Hg0) and oxidized mercury species (HgCl2, HgO, and HgS) on a novel metal organic framework (MOF) material, named Mg/DOBDC, with unsaturated metal centers was investigated using density functional theory (DFT) calculations. The results show that...
Understanding the nature of CO2 adsorption in porous materials is important to developing the next generation high performance adsorbents for CO2 capture. The mechanism of CO2 adsorption in a typical metal organic framework (MOF) material, named Mg/DOBDC (DOBDC=1,4-dioxido-2,5-benzenedicarboxylate), was investigated by experiments and theoretical calculations. Needle-shaped Mg/DOBDC crystals were...
There has been a controversy about the reactivity of coal/char combustion under oxyfuel and air conditions. The conversions of NCP anthracite and DT bituminous coal chars were studied under different atmospheres, using simultaneous thermogravimetry and differential scanning calorimetry (TG–DSC). A model of the intrinsic reaction rate was developed to obtain the variable activation energy at different...
Oxy-fuel combustion has been deemed a promising technology to reduce CO2 emissions from coal-fired power stations, and oxy-steam combustion technology is regarded to be the next-generation oxy-fuel combustion technology. The characteristics and mechanism of NO formation were numerically studied in the counter-flow laminar diffusion flame using methane as fuel. The comparisons of the N conversion rate...
It is difficult to selectively remove H2S and simultaneously avoid SO2 emission in biogas purification process with a low-cost and efficient method. In this study, an efficient hybrid adsorbent/photocatalytic composite (TiO2/zeolite) was synthesized for the H2S removal and SO2 capture by coating TiO2 on the surface of cheap natural zeolite with an ultrasonic-calcination way. The TiO2/zeolite showed...
Methane has been attracting increasing attention in the area of global carbon cycle and sustainable bioenergy. Interaction between iron containing minerals and microorganism played an important role in the anaerobic transformation of organic substances. In the current paper, change of methane production and microbial community in the goethite facilitated anaerobic digestion process using algal biomass...
Oxy-fuel combustion is regarded as a promising technology for CO2 abatement in coal-fired power generation. Oxy-steam combustion technology is regarded as the nextgeneration of oxy-fuel combustion technology because it has numerous advantages over O2/CO2 recycled combustion. The ignition of coal particles was investigated using numerical and experimental analysis in O2/N2 and O2/H2O atmospheres with...
The steam-enhanced carbonation reaction of CaO with CO 2 is a widely observed phenomenon, but its mechanism is unclear. This study proposed that OH − formation caused by the dissociation of H 2 O molecules may explain enhanced carbonation. The relationship of oxygen vacancies with OH − at different temperatures and steam fractions was established and integrated into...
An experimental study was carried out to examine the effect of different reaction conditions on the changes in the tumbling strength of coke samples from two types of pilot-scale coke ovens. Cokes were reacted with different CO 2 concentration and different duration at the CSR test temperature of 1373K and 1573K. Tumbling strength of the reacted cokes was measured using a typical CSR test...
Capturing CO 2 from the flue gases for sequestration is currently a key issue in environmental protection. Metal–organic frameworks (MOFs) are a new class of porous materials and have shown great promise for CO 2 adsorption and separation applications. While the linkers of MOFs influence the CO 2 adsorption performance greatly, the mechanism about it is still not clear. In...
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