The combustion characteristics (ignition delay and combustion period) of heavy fuel oil (HFO) for marine diesel engines may be affected by many factors such as density, carbon residue, asphaltene content, aromaticity, carbon/hydrogen (C/H) ratio, and so on. Investigation of the causes of operational problems in marine diesel engines should include examination of the fuel oil in service. The present study investigated the most important properties of HFO for such examination, using combustion tests and oil analysis. Marine HFOs with and without problems were analyzed using the same oil analyses and combustion tests. This study also tried to identify any threshold value of a fuel oil property related to poor ignition delay and combustion period. The constant volume combustion test apparatus (FIA 100), which has the same fuel injection mechanism as a diesel engine, was used in all the tests. This study reached the following conclusions: (1) Percentage of paraffinic carbon (%CP) and C/H mass ratio of marine HFO have a good correlation with the combustion characteristics. (2) Density has a higher correlation with the combustion characteristics than viscosity. (3) Carbon residue and asphaltene in fuel oil have lower correlations with ignition delay, but some correlation with combustion period. (4) Sulfur content has a low correlation with the combustion characteristics. (5) Threshold values of C/H mass ratio = 8.3 may indicate ignition delay and prolonged combustion period in fuel oils of poor quality.
The streamline method was extended to thermal oil-recovery simulation by developing an appropriate heat transport model based on the streamline method for implemention into a thermal recovery simulator. The heat transport model consisted of convection from the flowing phases and diffusion terms of gravity, capillary force, and conduction. An operator splitting technique was applied to decouple the convective and diffusive parts for separate solution. The convective part, a non-linear one-dimensional hyperbolic equation, was solved by the implicit single-point upwind scheme along the streamlines. The diffusive part, a non-linear, mixed hyperbolic-parabolic equation modeling gravity, capillary force and conduction, was solved using finite-difference discretization over the three-dimensional grid. The pressures for defining streamlines were obtained by solving the fluid flow equations with a finite-difference Newton method considering the compressibility, depletion and capillary forces. Simulations of hot water-flooding in two-dimensional and three-dimensional heavy-oil reservoirs were conducted to verify the model. The simulation results were compared with those of a commercial thermal simulator, which demonstrated that the streamline approach is a viable alternative to conventional finite-difference methods for heat transport calculations within a thermal simulator.
The reforming behaviors of hexane and isooctane were studied using microwave steam plasma under atmospheric pressure without additional plasma supporting gas. The experimental results showed that the reforming process for both hydrocarbons was rapid and that the product gas consisted predominantly of hydrogen and carbon monoxide. The reforming process was less dominant for higher hydrocarbons due to the supplementary energy required as indicated by the equilibrium calculation. The features of the proposed microwave steam plasma reforming system were presented with many advantages.
Aminosilane-modified mesoporous silica was prepared by grafting various aminosilanes on mesoporous silica, SBA-15, and the applicability as a novel adsorbent for CO2 capture and separation from flue gases was examined. Pore walls of SBA-15 were modified uniformly with aminosilanes by grafting and relatively high surface area and uniform pore size were retained. Adsorption capacities of CO2 in the presence of water were compared with those in the absence of water by a flow method. Adsorption capacities of aminosilane-modified SBA-15 were comparable in the presence and absence of water vapor. In particular, the adsorption capacity of (3-trimethoxysilylpropyl)diethylenetriamine SBA-15 reached 1.2 mmol·g−1 in the presence of water vapor at 333 K, which is comparable to the adsorption capacity of zeolite Na-Y in the absence of water vapor. In addition, these adsorbents were completely regenerated by heating to 423 K in a He flow.
Mo catalysts were prepared by impregnation of titania synthesized by the pH swing method which provides a TiO2 carrier with a high specific surface area (134 m2·g−1) and excellent mechanical properties. Dibenzothiophene (DBT) hydrodesulfurization (HDS) activity was estimated over the obtained catalysts under typical HDS reaction conditions for various Mo contents. The activity increased linearly with Mo content up to ca. 16 wt% MoO3 and then decreased for higher Mo loadings. The sulfur behavior on the sulfided Mo/TiO2 catalysts was elucidated under the reaction working conditions using a 35S radioisotope tracer method, or the HDS of 35S-labeled DBT. The results indicated that at a given temperature the H2S release rate constant (kRE) was almost constant irrespective of the Mo content, and the amount of labile sulfur (S0) increased linearly with the Mo content in parallel with the activity up to ca. 16 wt% MoO3. The optimal Mo dispersion was 5.2 atom/nm2, which is higher than the optimal Mo dispersion on 70 m2·g−1 TiO2 (4.2 atom/nm2). Comparison of kRE and S0 of the titania-based catalysts and the alumina-based catalysts suggested that the active phase consists of a 'TiMoS' phase exhibiting a promoting effect similar to the well-known 'CoMoS' phase (promotion of the MoS2 active phase by Ti atoms).
For the proposed synthesis of liquefied petroleum gas (LPG), MFI zeolite catalysts were prepared for selective conversion of methanol or dimethyl ether (DME) through either surface modification of parent ZSM-5 or isomorphous substitution of MFI metal heteroatoms. Fe3 +-exchanged ZSM-5 was most effective to improve C3-C4 fractional selectivity among the surface modified H-ZSM-5 catalysts. The presence of iron, gallium and/or aluminum among the framework heteroatoms of MFI metallosilicates was correlated with improved methanol conversion to LPG hydrocarbons. Zeolites containing gallium or gallium_aluminum catalyzed methanol conversion together with aromatization. The incorporation of iron into MFI framework greatly reduced aromatization and carbon-chain growth. Zeolite containing iron and aluminum was quite effective for improving the LPG fractional selectivity. Effects of the modification procedure with iron species on catalytic performance were verified. The co-existence of iron with aluminum as heteroatoms in the MFI framework provided the best selectivity compared to ion-exchange with Fe3 + and loading of iron or oxides. DME conversion over H-FeAlMFI-silicate and unmodified H-ZSM-5 confirmed the improvement in catalytic selectivity and stability.
NO decomposition over supported alkaline earth metal oxide catalysts was strongly dependent on the type of metal oxide support. Y2O3 was the most effective support. Ba/Y2O3 showed the highest NO decomposition activity, which decreased in the order of Ba/Y2O3 > Sr/Y2O3 > Ca/Y2O3 > Mg/Y2O3 ~ Y2O3. The catalytic activity of Ba/Y2O3 for NO decomposition at 900°C gradually increased with reaction time. The activity enhancement was due to the decomposition of barium carbonate into barium oxide during the reaction. Barium carbonate was completely decomposed by reduction with H2 at 900°C, resulting in significant enhancement of NO decomposition activity. The activity of Ba/Y2O3 increased with higher barium loading up to 5 wt%, and then became constant. There was a strong relationship between NO conversion and the amount of NO adsorption on Ba/Y2O3, suggesting that NO adsorption sites are the reaction sites for NO decomposition. The relationship between the activity for 1-butene isomerization, which is an indicator for the basicity of Ba/Y2O3 catalysts, and the activity for NO decomposition suggests direct participation of basic sites in the NO decomposition reaction over supported alkaline earth metal oxide catalysts.
Solvent extraction was applied to the separation of tar light oil and absorption oil, and solvent recovery in the separation of these coal tar fractions by extraction with secondary oil solvent. The liquid-liquid equilibria were measured with various combinations of oil and aqueous methanol phases that occur throughout the whole extraction process. Based on the equilibrium results, a process separating absorption oil and tar light oil simultaneously with a single aqueous solvent is suggested, in which the two feed oils also act as secondary solvents for mutual separation. In the separation of feed oils by aqueous methanol solution as solvent, nitrogen heterocyclic compounds in the absorption oil and the tar light oil were extracted preferentially to other compounds including homocyclic hydrocarbons and oxygen heterocyclic compounds. In the solvent recovery in the separation of absorption oil, the aqueous extract phase containing aqueous solvent and extractants was separated by tar light oil as secondary oil solvent. In the solvent recovery in the separation of tar light oil, the aqueous extract phase was separated by absorption oil as the secondary oil solvent. The distribution coefficients were not affected by the type of oil phase of coal tar fraction and by the presence of the extractants in the aqueous phase. The distribution coefficients in all cases of oil phases of absorption oil and tar light oil could be classified into three groups: monocyclic nitrogen compounds, bicyclic nitrogen compounds, and other compounds including hydrocarbons and oxygen compounds. By integrating the two separation processes of absorption oil and tar light oil into one process separating both coal tar fractions simultaneously with a single aqueous solvent, several extractors and solvents required in the two separate processes can be eliminated.