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The physical properties (density, kinematic viscosity, surface tension, and hydrogen solubility) and their correlations for a slurry-phase hydrocracking reaction were investigated with a vacuum residue (VR, as a feedstock) and hydrocracked products from VR conversion of 32.3%, 73.9% at different temperature and pressure conditions. As a result, the density, kinematic viscosity, and surface tension of the product decreased with converting VR, while the solubility of hydrogen increased. And the dependence of product properties on temperature showed to be similar to feedstock. Based on the measured data, the empirical correlations that can predict from VR to products were obtained with R-square of 0.9930 by modifying the existing correlations. From these properties change, it was confirmed that the hydrocracking temperature and the degree of the hydrocracking conversion of VR is the most dominant parameters to govern the change of physical properties. Finally, it was found that the mass transfer rate of hydrogen into oil is important because the hydrogen solubility (0.8 mol H2/kg feed or 0.16 wt.% on the feed weight at 160 bar, 410 ℃) on the liquid phase is much smaller than the chemical consumption of hydrogen (about 2–3 wt.% on the feed weight) for near full conversion of VR.

Globally, the demand for masks has increased due to the COVID-19 pandemic, resulting in 490,201 tons of waste masks disposed of per month. Since masks are used in places with a high risk of virus infection, waste masks retain the risk of virus contamination. In this study, a 1 kg/h lab-scale (diameter: 0.114 m, height: 1 m) bubbling fluidized bed gasifier was used for steam gasification (temperature: 800 °C, steam/carbon (S/C) ratio: 1.5) of waste masks. The use of a downstream reactor with activated carbon (AC) for tar cracking and the enhancement of hydrogen production was examined. Steam gasification with AC produces syngas with H

This study provides combined isothermal and non-isothermal pyrolysis properties of Kazakhstan coals necessary for development and optimization of thermal processes. Devolatilization properties are ...

In the present study, a syngas was produced by preparing coal water mixtures of two different concentrations and gasifying the coal water mixtures. An entrained-flow gasifier of 1 ton/day scale was used and, after undergoing a purification process, the produced syngas was applied to a modified diesel engine for power generation. As the gasification temperature increased, the carbon conversion and the cold gas efficiency were found to increase. In the composition of the produced syngas, the content of H2 remained constant, that of CO increased, and those of CO2 and CH4 decreased. The carbon conversion increased with equivalence ratio. A maximum cold gas efficiency of 66.1% was found at the equivalence ratio of 0.43. N2 was additionally supplied to verify the gasification characteristics depending on the gas feed flow rate. The optimum feed flow rate was verified at different slurry concentrations and equivalence ratio. The produced syngas was supplied to a modified diesel engine and operated depending on the syngas feed flow rate and the engine operation conditions. The brake thermal efficiency of the engine was constant regardless of the syngas feed flow rate. The diesel engine showed high efficiency despite the mixing of the syngas.

Cracking, steam reforming, dry reforming, and combined steam and dry reforming of toluene in model syngas were performed using catalysts to simulate tar removal produced during biomass gasification...

This study aims to optimize the oxy-circulating fluidized bed combustion (oxy-CFBC) process by reducing the amount of flue gas with high-purity carbon dioxide. To achieve this, the stable transition from air mode to oxy mode is tested and validated in a 0.1-MW oxy-CFBC test rig. The results prove that flue gas carbon dioxide separation can achieve 96 vol% (dry) through a stable transition from air mode to oxy mode. Moreover, flue gas production emitted in oxy mode is reduced to one fifth compared to air mode. The proven technologies and oxy-fuel combustion database from this test rig operating experience can be used as empirical operating parameters for the next steps such as demonstration and commercial-scale operation.

The effect of reaction temperature and time on the products and the asphaltene dispersion according to the residue conversion was investigated in a slurry-phase hydrocracking reaction. The experiments were carried out with two different approaches to control the hydrocracking reaction, which the reaction time was changed from 4 h to 20 h (at 410 °C) and the reaction temperature from 430 °C to 453 °C (for 1 h) at 100 bar (at 80 °C) of initial hydrogen pressure and 500 wt.ppm of molybdenum concentration. As a result, it was found that the control of the reaction time and reaction temperature may give different effect to the stability of the asphaltene in the liquid phase in spite of the same VR conversion. In order to understand this, the dipole moments of the liquid product and structural change of the asphaltene was compared. And it was found that enhancing hydrogenation reaction by increasing reaction time at low temperature delayed the time of decreasing point for dipole moments of the liquid phase and increased the length of alkyl chain of remaining asphaltene. Therefore, it is considered that the dispersibility of asphaltene with high polarity is increased. Additionally, it was found that enhancing hydrogenation can also improve the catalyst dispersion in the liquid phase below 80% of residue conversion.

This study investigates air gasification properties of SRF with high content of residual mixed waste plastic in a 1 kg/h lab scale bubbling fluidized bed gasifier. Gasifier internal diameter is 0.114 m and its height is 1 m. Silica sand particles with a mean diameter of 400 μm is used as the bed material. During the gasification experiments the effect of bed temperature is determined in the range of 600–900 °C and the effect of air-to-fuel equivalence ratio (ER) is investigated in the range of 0.15–0.30. Gas analysis is conducted using a non-dispersive infrared analyzer and gas chromatograph. As the operating temperature and ER increases, the gas yield increases, and tar yield decreases. The yield of CO, CH4, H2, and C2H2 in the gas product increases with temperature, whereas those of CO2, C2–C3 hydrocarbons decreases. The increase in ER decreases the concentrations of CO, CH4, H2, and C2–C3 hydrocarbons and increases the CO2 in the gas product. H2/CO ratio substantially increases with rising temperature and decreases with rising ER. Carbon conversion efficiency (CCE) and cold gas efficiency reach peak at 800 °C and ER of 0.25.

To improve the fluidity of a coal water mixture (CWM) having lower viscosity and higher solid concentration, the effects of surfactants (five kinds) and experimental variables such as temperature (5-65 °C), pH (1-11), particle size distribution (PSD) on the viscosity characteristics of two different coals (Shenhua and Kideco Coal) were investigated. Relatively economical surfactants were chosen in this study: sulfonated melamine formaldehyde polymer (SMF-30), naphthalene formaldehyde sulfonate (Sikament-NN), naphthalene sulfonate water reducer (NSWR), naphthalene formaldehyde sulfonate (PC-1000) and poly-carboxylate (PC). The SMF-30, an anionic surfactant, revealed the most significant reduction in viscosity of CWM among the five surfactants since the SMF-30 forms electric double layer on the surface of coal, and the repulsive force of this layer surpasses the aggregation of coal particles. In addition, the viscosity of CWM decreased with increasing pH and temperature, in particular, the increase in OH- on the surface of coals by the addition of NaOH caused the increase in the repulsive force between the negatively charged coal particles. Furthermore, the very fine particles (less than 45 μm) of coals should be removed before making CWMs since it revealed the increase in viscosity of CWMs.

Entrained-flow gasifiers used in commercial integrated gasification combined cycles are usually oxygen-blown. However, oxygen-blown gasification system is expensive to install and operate due to the equipment involved in oxygen purification and supply. To resolve this issue, this study mixed air and oxygen to perform coal gasification. An entrained-flow gasifier of 1 T/D scale was used with the coal water mixture as feedstock. Gasification was carried out at a temperature range of 970–1220 °C, an equivalence ratio of 0.25–0.62, and an air/O 2 ratio of 2.17–9.0. With an increasing gasification temperature, the amount of CO in the syngas increased while CO 2 and CH 4 decreased. Carbon conversion and cold gas efficiency continued to increase with the gasification temperature. In the equivalence ratio test, cold gas efficiency reached 52.1% at around 0.53 before decreasing under a fixed air flow rate of 90 N m 3 /h. By performing gasification with a varying air/O 2 ratio after fixing the flow rate, the influence of the equivalence ratio was examined. In addition, the influence of the flow rate was observed through changes in the air/O 2 ratio of the gasification agent with fixing the equivalence ratio. The maximum carbon conversion and cold gas efficiency were 90.7 and 57.7%, respectively, and the optimal air/O 2 ratio fell in the range of 2.86–3.1.

Biomass combustion in the oxy-fuel circulating fluidized bed is a promising technology to maximize the negative carbon dioxide emission and reduce pollutants emission in power plants. However, biomass ash related behaviors under oxy-combustion with kaolin additives still lack sufficient information. In this study, kaolin was used as an additive to manage ash problems during oxy-biomass combustion in a 0.1 MWth circulating fluidized bed combustion facility. Kaolin was fed at ratios of kaolin/wood pellet (wt./wt.): 0.21 and 0.25 by separately feeding or pre-mixing, respectively. The sampled ashes were characterized using X-ray fluorescence and X-ray diffraction analysis. Additionally, the potassium capture performance, slagging and fouling indices, attrition characteristics, and strength were also evaluated. The results revealed that potassium capture performance was improved by up to 24% at the ratio of kaolin/wood pellet (0.25) and kalsilite (KAlSiO4) within ash increased by adsorption on the metakaolin surface of gaseous potassium. The fouling formation decreased from 0.43 without kaolin to 0.07–0.15 with kaolin. In terms of oxy-fuel operation, SO2 emission was decreased when kaolin used, performing a high CO2 concentration of over 93 vol% and combustion efficiency of over 99%.

The effects of plasma power (1–1.8 kW), oxygen/fuel (0–2.5) and steam/fuel ratios (0–1) on the gasification characteristics of glass fiber-reinforced plastic (GFRP) wastes have been determined in a microwave plasma reactor. GFRP, which is thermosetting plastic composed of glass fibers embedded within a polymer matrix, was used as an experimental sample. While carbon conversion increased with oxygen/fuel ratio, syngas heating value and cold gas efficiency decreased with oxygen supply due to the onset of combustion. With increasing steam/fuel ratio, water-gas shift and ion-reforming reaction favored higher concentration of H2. Increasing the plasma power was found to promote the conversion of carbon dioxide to carbon monoxide. The char surfaces of GFRP that were subjected to variable power and oxygen supplies were analyzed by scanning electron microscopy.

The hydrodynamic velocity and effect of the reaction temperature on the cracking performance were investigated for the production of light oil through the rapid pyrolysis of heavy oil in a circulating fluidized bed reactor. From this study, the gas velocity in the loop seal to prevent slugging, the transport gas velocity to form a dense phase of solids on the bottom of the riser, and the minimum bubbling fluidization velocity for stable solid circulation in the reheater were determined. Under the steady supply of feed through the internal mixing with steam inside the feed nozzle, the reactivity for a temperature change from 527 to 574 °C was investigated. As a result, the residue (>535 °C) conversion and liquid yield of up to 71.1 and 78.2%, respectively, were found. The maximum impurity removal rates for sulfur, Conradson carbon residue, and metals (nickel and vanadium) were found to be 18.7, 50.4, and 83.6%, respectively.

Tar formation resulting during lignocellulosic biomass gasification is a major impediment to utilizing biomass energy sources, in that it blocks and fouls the processing equipment; as such, any tar present in the produced syngas much be effectively removed. This study analyzes the ability of commercially available Ni and Ru based CH4 reforming catalysts to effect tar removal and compares deactivation characteristics. Toluene was used as the model biomass tar at concentrations of 30 and 100 g/Nm3. Several additional parameters were also tested, including reaction temperatures (400–800 °C), space velocities (5000–30,000 h−1), and the steam/toluene ratios (2–20). The variation of toluene conversion and product gas composition with reaction conditions was analyzed. Overall, H2 and CO production were favored by the Ru catalyst and generally increased with temperature. Conversion also increased with temperature, with conversions higher than 90% obtained at 800 °C.

This study investigated the hydrocracking reaction performance of Mo-dispersed catalysts in relation to operating conditions in a bench scale slurry bubble column reactor. Experiments were performed at various temperatures (405–435 °C), LHSV (0.2–0.45 h − 1 ), superficial gas velocities (0.4–2.2 cm/s) and pressures (80–180 bar). As a result, it was found that the temperature and LHSV influenced the VR conversion, and the yield and properties of the product had a strong dependence on the VR conversion. And a reliable correlation between product yield, properties and VR conversion can be obtained using these relationships. In terms of the hydrogenation reaction, the change of hydrogen pressure significantly affected the removal of impurities, with reduced sediments. Even with the dispersed catalysts, it was confirmed that the sediment content rapidly increased at a certain VR conversion (about 50–60 wt%) as similarly a heterogeneous catalyst was shown. Finally, it was found to keep the VR conversion below 60 wt% and the pressure above 120 bar for the stable operation of the slurry-phase hydrocracking and sediment control.

Nanostructured silicon (Si) is useful in many applications and has typically been synthesized by bottom-up colloid-based solution processes or top-down gas phase reactions at high temperatures. These methods, however, suffer from toxic precursors, low yields, and impractical processing conditions (i.e., high pressure). The magnesiothermic reduction of silicon oxide (SiO2) has also been introduced as an alternative method. Here, we demonstrate the reduction of SiO2 by a simple milling process using a lab-scale planetary-ball mill and industry-scale attrition-mill. Moreover, an ignition point where the reduction begins was consistently observed for the milling processes, which could be used to accurately monitor and control the reaction. The complete conversion of rice husk SiO2 to high purity Si was demonstrated, taking advantage of the rice husk’s uniform nanoporosity and global availability, using a 5L-scale attrition-mill. The resulting porous Si showed excellent performance as a Li-ion battery anode, r...

Technology for converting biomass such as rice husk into a useable energy sources are key to address energy consumption issues. The effects of temperature (600–900 °C), equivalence ratio (ER, 0.15–0.3), and addition of catalyst on the gasification characteristics of rice husk were investigated in a bubbling fluidized bed reactor with an inside diameter of 0.067 m and a height of 1.55 m. As the reaction temperature and ER were increased, the concentrations of CO and CO 2 in the product gas decreased. Slight increases in CH 4 and H 2 concentrations were also observed with increasing temperature. Throughout the temperature range of interest, an increase in ER resulted in decrement of both the higher heating value of the product gas and the cold gas efficiency. Furthermore, the effect of operating condition and addition of bed material were determined in a bubbling fluidized bed reactor. An increase in reaction temperature and ER decreased the tar content. The addition of calcined dolomite and olivine in the bed material reduced the amount of tar during rice husk gasification in a bubbling fluidized bed reactor. These results have the potential to be applied to the conversion of biomass into a useable energy source.

We investigate fluidization characteristics of the mixture of rice husk, silica sand and rice husk ash as a preliminary study for valuable utilization of rice husk ash obtained from gasification of rice husk in a fluidized bed reactor. As experiment valuables, the blending ratio of rice husk and sand (rice husk: sand) is selected as 5:95, 10:90, 20:80 and 30:70 on a volume base. Rice husk ash was added with 6 vol% of rice husk for each experiment and air velocity to the reactor was 0~0.63 m/s. In both rice husk/sand and rice husk/sand/ash mixture, the minimum fluidization velocity (Umf) is observed as 0.19~0.21 m/s at feeding of 0~10 vol.% of rice husk and 0.30 m/s at feeding of 20 vol.% of rice husk. With increasing the amount of rice husk up to 30 vol.%, can not measure due to segregation behavior. The mixing index for each experiment is determined using mixing index equation proposed by Brereton and Grace. The mixing index of the mixture of rice husk/sand and rice husk/sand/ash was 0.8~1 and 0.88~1, respectively. The optimum fluidization condition was found for the good mixing and separation of rice husk ash.

Steam reforming of tar produced from biomass gasification was conducted using several Ni-based catalysts. In lab- scale, the catalytic steam reforming of toluene which is a major component of biomass tar was studied. A fixed bed reactor was used at various temperatures of 400-800 ℃. Ru (0.6 wt%) and Mn or K (1 wt%) were applied as a promoter in Ni based catalysts. Generally, Ni/Ru-K/Al2O3 catalyst shows higher performance on steam reforming of toluene than Ni/Ru-Mn/Al2O3 catalyst. Used catalysts were analyzed by XRD and TGA to detect sintering and carbon deposition. Base on the lab-scale studies, the monolith and pellet type catalysts were tested in 1 ton/day scale biomass gasification system. Ni/Ru-K/Al2O3 monolith catalyst shows high tar reforming performance at high temperature. In addition, Ni/Ru-Mn/Al2O3 monolith catalyst was showed deactivation with operation time. Reforming performance of Ni/Ru-K/Al2O3 pellet catalyst which showed 66.7% tar conversion at 587 ℃ was compared to regenerated one. Overall, Ni/Ru-K/Al2O3 pellet catalyst shows higher stability and performance than other used catalysts.

The catalytic steam reforming of the major biomass tar component, toluene, was studied over two commercial Ni-based catalysts and two prepared Ru–Mn-promoted Ni-base catalysts, in the temperatures range 673–1073 K. Generally, the conversion of toluene and the H2 content in the product gas increased with temperature. A H2-rich gas was generated by the steam reforming of toluene, and the CO and CO2 contents in the product gas were reduced by the reverse Boudouard reaction. A naphtha-reforming catalyst (46-5Q) exhibited better performance in the steam reforming of toluene at temperatures over 873 K than a methane-reforming catalyst (Reformax 330). Ni/Ru–Mn/Al2O3 catalysts showed high toluene reforming performance at temperatures over 873 K. The results indicate that the observed high stability and coking resistance may be attributed to the promotional effects of Mn on the Ni/Ru–Mn/Al2O3 catalyst.

Carbonization is a low-temperature thermochemical process that converts organic matter in the absence of oxygen mainly into char, gas, and liquids. Bio-coke is a char prepared from a mixture of biomass/charcoal and a coal blend. It can reduce greenhouse gas emissions by replacing coke and reducing coal consumption in the ironmaking process. In this study, the carbonization characteristics such as char conversion, gas and tar composition of bio-coke were determined using a batch-type carbonization reactor. Yellow poplar wood used as a biomass was added to a coking coal in different ratios (0, 10, 15, 20, and 30 wt%) and the resulting raw bio-coke was carbonized at different final temperatures (500–800 °C). The calorific value of bio-coke was higher than 7000 kcal/kg, exceeding the standard value. Moreover, the initiation combustion temperature of the resultant bio-coke determined using TGA was in the range of 400–600 °C. It is concluded that bio-coke is a suitable substitute for conventional fossil fuels reducing CO2 emissions.

Asphaltene precipitation is known as a challenging issue to fully upgrade heavy oils. In this study, asphaltene dispersion stability and sediment formation for a slurry phase hydrocracking reaction of vacuum residue was investigated with changes of temperatures (405–435 °C), LHSV (0.20–0.45 h r - 1 ), pressures (80–180 bar) and superficial gas velocities (0.4–2.2 cm/s) in a bench-scale continuous system. The characteristics of dispersion stability were examined with the solubility parameters at the flocculation point (UV titration), the structure of the asphaltenes (H-NMR), and sediment content in the liquid product (Hot filtration). As results, it was found that the dispersion stability of asphaltene was mainly dependent on the VR conversion. In particular, at about 50% of the VR transition, the solubility was found to be unstable and the amount of deposition increased dramatically. At the same time, microscopic observation directly confirmed asphaltene flocculation. However, when H2 partial pressure was increased, the hydrogenation reaction of asphaltene was promoted so that it could reduce sediment formation and improve both the asphaltene solubility and structure for the stable dispersion. On the other hand, increasing the superficial gas velocity did not give an effect on the asphaltene dispersion stability.

Implementation of circulating fluidized bed (CFB) boilers in the energy sector has witnessed a steady increase owing to their afforded advantages of operational flexibility in terms of compliance with several low-grade fuels and in-situ DeSOx and DeNOx capabilities. In recent years, the rise in global warming and development of intermittent power-generation technologies have stressed the need for development of techniques to afford high-efficiency low-emission (HELE) power-generation, effective carbon capture and storage, and flexible operation of thermal power plants. To meet these demands, the Future Energy Plant Convergence Research Center (FEP CRC) has investigated oxy-combustion technologies for CFB boilers that use low-grade fuels with calorific values

Oxy-combustion with a circulating fluidized bed (Oxy-CFBC) can facilitate the separation of high CO2 concentration and reduce emissions by biomass co-firing. This study investigated Oxy-CFBC characteristics such as temperature, solid hold-up, flue gas concentrations including CO2, pollutant emissions (SO2, NO, and CO), combustion efficiency and ash properties (slagging, fouling index) with increasing input oxygen levels (21–29 vol%), and biomass co-firing ratios (50, 70, and 100 wt% with domestic wood pellet). The possibility of bio-energy carbon capture and storage for negative CO2 emission was also evaluated using a 0.1 MWth Oxy-CFBC test-rig. The results show that combustion stably achieved with at least 90 vol% CO2 in the flue gas. Compared to air-firing, oxy-firing (with 24 vol% oxygen) reduced pollutant emissions to 29.4% NO, 31.9% SO2 and 18.5% CO. Increasing the biomass co-firing from 50 to 100 wt% decreased the NO, SO2 and CO content from 19.2 mg/MJ to 16.1 mg/MJ, 92.8 mg/MJ to 25.0 mg/MJ, and 7.5 mg/MJ to 5.5 mg/MJ, respectively. In contrast to blends of sub-bituminous coal and lignite, negative CO2 emission (approximately −647 g/kWth) was predicted for oxy-combustion only biomass.

The adoption of oxy-combustion in a circulating fluidized bed (CFB) producing ultra-supercritical (USC) steam has been investigated to increase energy efficiency and reduce CO2 emissions of coal-fired power plants. This paper presents a techno-economic analysis for 500 MWe USC-CFB power plants with air- and oxy-combustion in the presence of CO2 capture. An amine absorber unit (AAU) and a CO2 processing unit (CPU) were used to capture CO2 in the air- and oxy-combustion power plants, respectively. The air-combustion power plant without CO2 capture (Case 1) showed the highest net electricity efficiency (46%), whereas the introduction of an AAU in the air-combustion power plant (Case 2) reduced the net efficiency to 36%. The net efficiency (39%) of the oxy-combustion power plant with CPU (Case 3) was higher than that of Case 2 owing to the recycling of hot flue gas. The levelized cost of electricity (LCOE) of Case 3 (59 $/MWh) was lower than that of Case 2 (64 $/MWh), which demonstrated that oxy-combustion was advantageous compared to air-combustion in a scenario with CO2 capture. The sensitivity analyses of the electricity price and CO2 credit showed economic situations where Cases 2 and 3 would be profitable.

The pyrolysis characteristics of GFRP (glass fiber reinforced plastic) were determined under isothermal conditions at 500–1000 °C using a thermo-balance reactor (TBR) and wire mesh reactor (WMR). The kinetics parameters for the GFRP were derived using the activation energy, of 28.17 kJ mol−1, of frequency factor, 2.12 s−1, and reaction order, of 0.48–0.8. The structural variations in the GFRP char were determined using BET, SEM, and FT-IR techniques. Organic compounds and polymers were decomposed with increasing temperature. The experimental results showed that increasing the temperature and reaction time favored polymer scission at temperature of 600–1000 °C with residence time of 2–10 s.

The pyrolysis characteristics of GFRP (Glass Fiber Reinforced Plastic), which is a thermosetting plastic composed of glass fibers and polymer compounds, were determined under non-isothermal conditions while heating at 5–20 °C/min from 500 to 900 °C using a thermo-gravimetric analyzer (TGA) and a batch-type pyrolyzer. The kinetic parameters for the GFRP were derived from the Freedman method with resultant activation energy ranging from 41.4 kJ/mol to 78.4 kJ/mol. The main components of the product gases were carbon monoxide from the ether and carbonyl decomposition of polymer and hydrogen from the aromatic ring breakage. The structural variations in the GFRP char were determined using BET, SEM, and FT-IR techniques. The surface area of GFRP char exhibited its maximum value at 600 °C, decreasing at higher temperatures with the collapsing macro-pore structure. The decomposed portion of the polymers attached to the glass fiber increased when increasing the temperature from SEM image. These data are useful for understanding the GFRP pyrolysis and gasification processes.

>> The catalytic steam reforming of toluene, a major component of biomass tar, was studied using severalcatalysts at various temperatures 400-800℃, kind of metal, and metal loading content. Ru and K promoted Ni-basecatalyst were prepared, and used for steam reforming of toluene with steam/toluene molar ratio of 25. Concentrationof toluene in reactant flow is 30 g/Nm 3 that is usual content of tar from biomass gasifier. The result from experiments showed that H 2 content in product gas and toluene conversion increased with temperature. Where inhigh temperature range, CO and CO 2 content in product gas were affected mainly by Boudouard reaction. Ni/Ru-K(3wt%)/Al 2 O 3 catalyst showed best performance on steam reforming of toluene than used catalysts in this studyat whole temperature. Catalysts have been characterized by XRD, TG. XRD analysis displayed that Ni particlesize on Ni/Ru-K (3wt%)/Al 2 O 3 catalyst was 29.4nm. Activation energy of Ni/Ru-K (3wt%)/Al 2 O 3 catalyst was calculated 36.8kJ/mol by Arrhenius plot.

Considering the importance of the detailed resolution of the reacting flow field inside a gasifier, the objective of this study lies on to investigate the effect of important variables to influence on the reacting flow and thereby to clarify the physical feature occurring inside the gasifier using a comprehensive gasifier computer program. Thus, in this study the gasification process of a 1.0 ton/day gasifier are numerically modeled using the Fluent code. And parametric investigation has been made in terms of swirl intensity and aspect ratio of the gasifier. Doing this, special attention is given on the detailed change of the reacting flow field inside a gasifier especially with the change of this kind of design and operation parameters. Based on this study, a number of useful conclusions can be drawn in the view of flow pattern inside gasifier together with the consequence of the gasification process caused by the change of the flow pattern. Especially, swirl effect gives rise to a feature of a central delayed recirculation zone, which is different from the typical strong central recirculation appeared near the inlet nozzle. The delayed feature of central recirculation appearance could be explained by the increased axial momentum due to the substantial amount of the presence of the coal slurry occupying over the entire gasifier in gasification process. Further, the changes of flow pattern are explained in detail with the gasifier aspect ratio. In general, the results obtained are physically acceptable in parametric study.

The extra-heavy oil fraction upgrading process, which consisted of a pyrolyzer and a bubbling bed as a combustor/gasifier, was developed. Prior to operating a dual circulating fluidized bed reactor, the transition velocities of flow regime were determined at different temperatures using silica sand particles as the bed material. The transition velocities included minimum fluidization velocity (Umf), transition velocity to turbulent fluidization (Uc, Uk) and transport velocity (Utr). The minimum fluidization velocity determined by measuring bed pressured drop with increasing gas velocity was observed to decrease with increasing temperature. Both the transition velocities from bubbling to turbulent fluidized bed behavior determined by measuring bed pressure drop fluctuation and transport velocity from turbulent to fast fluidized bed behavior by emptying time method increased with increasing temperature. Based on the experimental data, correlations are proposed to predict the transition velocities at different temperatures. As the actual dual circulating fluidized bed reactor operation occurs at relatively high temperature, the correlations obtained in this study are directly applicable to the extra-heavy oil fraction upgrading process. Thus, the transition velocities and flow regimes in a dual circulating fluidized bed reactor are determined.

A novel process has been developed at KIER (Korea Institute of Energy Research) for upgrading extra-heavy oil fractions. This process uses a rapid thermal pyrolysis (RTP) of extra-heavy oil with a gasifier/combustor of RTP residue to produce syngas as well as to supply heat to the pyrolyzer. Unreacted carbon in RTP residues from the pyrolyzer are used as a feedstock to the gasifier/combustor. The RTP residue is mostly sand with 1 wt % of petroleum coke.The possibility that product gas from the gasifier/combustor can supply heat to the pyrolyzer is examined. A continuous fluidized bed reactor with the maximum capacity of 10 kg/h (0.05 m I.D. × 1.2 m high) was designed and constructed for RTP residue gasification/ combustion. Air, oxygen, and steam were used as gasifying agents. The results of gasification are evaluated, including product gas composition, carbon conversion, gas yield, and heating value of the product gases. In air-blown gasification, the HHV (higher heating value) of the product gas ranges from 72.3 to 303.2 kcal/m 3 , which is lower than that of typical gasification. The carbon conversion is below 0.37, due to the low reactivity of petroleum coke and the diluting effects of nitrogen. In contrast, carbon conversion was greater than 0.93 with a higher equivalence ratio (ER = 1.0) in the O2-blown gasification mode. Product calorific values of up to 3739 kcal/m 3 can be obtained, with the steam serving as a gasifying agent.

A wire mesh reactor was used to investigate the devolatilization process of coal particle during entrained flow gasification. Coal from Indonesia East Kalimantan mine, which has high moisture and high volatile matter, was chosen as a sample. Experiments were carried out at the heating rate of 1,000 °C/s and isothermal condition was kept at peak temperature under atmospheric pressure. The char, tar and gas formation characteristics of the coal as well as the composition of the gas components at peak temperatures were determined. The experimental results showed that devolatilization process terminated when temperature reached above 1,100 °C. Most of tar was formed at about 800 °C, while the rate of tar formation decreased gradually as the temperature increased. CH4 was observed at temperatures above 600 °C, whereas H2 was detected above 1,000 °C. The amount of formed gases such as H2, CO, CH4 and C n H m increased as the temperature increased. From the characteristics of devolatilization with residence time, it was concluded that devolatilization terminated within about 0.7 second when the temperature reached 1,000 °C. As the operating temperature in an entrained flow gasifier is higher than ash melting temperature, it is expected that the devolatilization time of high volatile coal should be less than one second in an entrained flow gasifier.

The BTL (biomass-to-liquid) process is an attractive process that produces liquid biofuels from biomass. The FT (Fisher–Tropsch) process is used to produce synfuels such as diesel and gasoline from gasified biomass. However, the H2S (hydrogen sulfide), COS (carbonyl sulfide) and CO2 (carbon dioxide) in the syngas that are produced from the biomass gasifiers cause a decrease of the conversion efficiency and deactivates the catalyst that is used in the FT process. To remove the acid gases, a pilot-scale methanol absorption tower producing diesel at a rate of 1 BPD (barrel per day) was developed, and the removal characteristics of the acid gases were determined. A total operation time of 500 h was achieved after several campaigns. The average syngas flow rate at the inlet of methanol absorption tower ranged from 300 to 800 L/min. The methanol absorption tower efficiently removed H2S from 30 ppmV to less than 1 ppmV and COS from 2 ppmV to less than 1 ppmV with a removal of CO2 from 20% to 5%. The outlet gas composition adhered to the guidelines for FT reactors. No remaining sulfurous components were found, and the tar component was analyzed in the spent methanol after long-term operations.

To investigate the kinetic characteristics of coking coal mixed with biomass during pyrolysis, thermogravimetric (TG) and thermo-balance reactor (TBR) analyses were conducted under non-isothermal and isothermal condition. Yellow poplar as a biomass (B) was mixed with weak coking coal (WC) and hard coking coal (HC), respectively. The calculated activation energies of WC/B blends were higher than those of HC/B blends under non-isothermal and isothermal conditions. The coal/biomass blends show increased reactivity and decreased activation energy with increasing biomass blend ratio, regardless of the coking properties of the coal. The different char structures of the WC/B and HC/B blends were analyzed by BET and SEM.

Glycerol which is a byproduct of biodiesel production is considered as a potential feedstock for syngas production with the increase of biodiesel demand. In this study, the charac- teristics of glycerol gasification under a microwave plasma torch with varying oxygen and steam supply conditions were investigated. The experimental results demonstrated that the gasification efficiency and syngas heating value increased with the supplied microwave power while the increase of oxygen and steam led to a lower gasification performance. In order to achieve high carbon conversion and cold gas efficiency in the microwave plasma gasification of glycerol, the O2/fuel ratio should be maintained at 0e0.4. It was revealed that the fuel droplet size and the mixing effect and retention time inside the plasma flames are critical factors that influence the product gas yield and gasification efficiency. This study verified that syngas with a high content of H2 and CO could be effectively produced from glycerol through microwave plasma gasification.