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Production of producer gas from waste cooking oil in a fluidized bed reactor: Influence of low-temperature oxidation of fuel
... However, some studies use different technologies with other types of biofuels produced through the valorization of WCO, such as the production of hydrogen-rich syngas in gasification, bio-oils through various types of pyrolysis, and biokerosene, among others. Table 3 shows the leading technologies used to produce biofuel and the product of that technology [23][24][25][26][27][28][29][30][31][32][33][34]. ...
... The ashes produced during this process are removed from the bottom of the gasifier [40,43,51,54]. Kim (2015) carried out WCO valuation studies of soy oil to produce syngas gasified with air in a fluidized bed reactor. The gas produced was filtered with activated charcoal. ...
... It was observed that oxidation at low temperature (808.5 °C) significantly changed the composition of the fuel, making the WCO more favorable to the gasification reaction, producing a more significant amount of hydrogen and carbon monoxide. In addition, with the filtration of activated charcoal, the gas (WCO product) fulfilled the tar requirement (<0.1 g/Nm 3 ) for the energy production of an engine by syngas [30]. ...
In search of a more sustainable society, humanity has been looking to reduce the environmental impacts caused by its various activities. The energy sector corresponds to one of the most impactful activities since most energies produced come from fossil fuels, such as oil and coal, which are finite resources. Moreover, their inherent processes to convert energy into electricity emit various pollutants, which are responsible for global warming, eutrophication, and acidification of soil and marine environments. Biofuels are one of the alternatives to fossil fuels, and the raw material used for their production includes vegetable oils, wood and agricultural waste, municipal waste, and waste cooking oils (WCOs). The conventional route for WCO valorization is the production of biodiesel, which, as all recovery technologies, presents advantages and disadvantages that must be explored from a technical and economic perspective. Despite its successful use in the production of biodiesel, it should be noticed that there are other approaches to use WCO. Among them, thermochemical technologies can be applied to produce alternative fuels through cracking or hydrocracking, pyrolysis, and gasification processes. For each technology, the best conditions were identified, and finally, projects and companies that work with this type of technology and use WCO were identified.
... Li et al. reported that WCO can be entirely converted into syngas at 750 C in the presence of ferric oxide (Fe 2 O 3 ), with H 2 and carbon monoxide (CO) contents of 48% and 10% in the syngas, respectively . Kim et al. used waste soybean oil as a raw material to generate a producer gas by gasification with air, and reported that low-temperature oxidation improves the quality of the gas (Kim et al., 2015). ...
... WCO is an organic substance consisting of hydrocarbon and oxygen macromolecules. Previous research indicates that WCO can be cracked into CO, H 2 , C, and other micromolecular gases (Kim et al., 2015). H 2 , CO, and C can effectively reduce Fe 3 O 4 as well as iron oxides. ...
... The equilibrium diagram of reduction of iron oxides by H 2 and CO is shown in Fig. 3. When the volume fractions of H2 H2þH2O and CO COþCO2 are above 4.0% and 11.5%, respectively, Fe 3 O 4 reduces to ferrous oxide (FeO) at 1250 C. In cracking of WCO, CO and H 2 are the primary gas constituents, similar to what is seen in the generation of syngas from WCO (Kim et al., 2015), indicating that iron oxides would be readily reduced at high temperature. This provides a theoretical support that WCO can be used as a reductant in this application. ...
Currently, waste cooking oil (WCO) as a renewable energy is not widely utilized. Copper slag cleaning in an electric furnace is a critical process for reducing the excessive magnetite (Fe3O4) present in the copper slag to decrease the slag viscosity, which can promote the sedimentation of matte/copper in the slag, thus reducing the copper content of slag. In this study, laboratory-scale experiments were performed for copper slag cleaning using WCO as a reductant instead of traditional fossil fuel-based reductants. The results showed that the Fe3O4 content of the copper slag significantly decreased from 17.8% to 4.2% with the addition of 2 mL of WCO at 1250 °C. To better understand the reduction process, the cracking characteristics of WCO over corundum and Fe3O4 were investigated at 600–1300 °C. The cracking of 1 mL of WCO over corundum and Fe3O4 at 1300 °C yielded 1450 and 1770 mL of gases (H2, CO, CO2, and methane (CH4)), respectively. Combined with thermodynamic analysis, it was found that all the cracking products participated in the reaction of copper slag cleaning. This work offers a novel approach for the clean utilization of WCO for copper slag cleaning.
... Kim et al. [99] performed the pyrolysis conversion of waste soybean oil in a bench-scale fluidized-bed reactor gasified with air. Other auxiliaries include a cyclone to remove the formed char, fabric filter to capture the tar and moisture from the gaseous products collected using gasbags. ...
... For instance, the uneven heat distribution in conventional pyrolysis affects the heating process, prolonging the pyrolysis reaction time. Previous studies reported that 2.5 to 13 h were required to operate the pyrolysis process, especially for the time to start heating the furnace, achieving the steady-state conditions and cooling process [73,99,100]. The pyrolysis reaction time may, in turn, influence the yield and properties of the pyrolysis products. ...
Pyrolysis is a potential technology used for the transformation of municipal wastes into energy products such as biofuel. Existing reviews on pyrolysis mainly focus on agroforestry biomass and conventional pyrolysis heating techniques. There is limited literature on the application of recent pyrolysis techniques, types of reactors, key operating parameters, and properties of pyrolysis products from conventional versus recent/novel pyrolysis techniques, and particularly the application of the oil products in fuel engines. Here we focus on the performance of various pyrolysis techniques for valorizing municipal wastes, with an explicit emphasis on the progress and application of co-pyrolysis as a recent technique for value-added products recovery from municipal wastes. We review the main operating parameters of co-pyrolysis, concerns and disputes arisen from the technique, and the resultant liquid fuel properties. In particular, co-pyrolysis using microwave heating shows proficiency to resolve several drawbacks of conventional pyrolysis techniques such as reduced oxygen content and viscosity and increased calorific value of liquid oil, hence promising as a method to generate environmental friendly and sustainable third-generation fuels. Sorting of municipal wastes is recommended as an approach to improve the feasibility of co-pyrolysis by having desired quantity and type of municipal wastes as the feedstock, and more research and development on co-pyrolysis utilizing municipal wastes is necessary to maximize the yield and quality of target pyrolytic products. Thus, we conclude that co-pyrolysis is a feasible and sustainable method for recovering biofuel from municipal wastes to obtain green energy and energy security.
... Despite the production of biodiesel and biolubricants from WCO, it can also serve as a promising precursor for hydrogen and/or synthesis gas (syngas) production via the thermochemical pathway. Young-Doo Kim et al. [18] studied fresh and waste soybean oil gasification with air in a bench-scale fluidised-bed reactor. The effects of the equivalence ratio on the gas composition and tar content, as well as low-temperature oxidation on the fuel properties, were examined. ...
... Therefore, the produced syngas quality in this experimental research would require additional tar removal or process optimization if the syngas was planned to be used for power generation in the ICE. Kim et al. [18] used the activated carbon filter installed just after the electrostatic precipitator in the treatment of the WCO to syngas in a fluidised-bed reactor. It was reported that the filter did not affect the concentration of the syngas, but the tar content decreased significantly from 0.308 g/Nm 3 to 0.069 g/Nm 3 . ...
The depletion and usage of fossil fuels causes environmental issues and alternative fuels and technologies are urgently required. Therefore, thermal arc water vapor plasma for a fast and robust waste/biomass treatment is an alternative to the syngas method. Waste cooking oil (WCO) can be used as an alternative potential feedstock for syngas production. The goal of this experimental study was to conduct experiments gasifying waste cooking oil to syngas. The WCO was characterized in order to examine its properties and composition in the conversion process. The WCO gasification system was quantified in terms of the produced gas concentration, the H2/CO ratio, the lower heating value (LHV), the carbon conversion efficiency (CCE), the energy conversion efficiency (ECE), the specific energy requirements (SER), and the tar content in the syngas. The best gasification process efficiency was obtained at the gasifying agent-to-feedstock (S/WCO) ratio of 2.33. At this ratio, the highest concentration of hydrogen and carbon monoxide, the H2/CO ratio, the LHV, the CCE, the ECE, the SER, and the tar content were 47.9%, 22.42%, 2.14, 12.7 MJ/Nm3, 41.3% 85.42%, 196.2 kJ/mol (or 1.8 kWh/kg), and 0.18 g/Nm3, respectively. As a general conclusion, it can be stated that the thermal arc-plasma method used in this study can be effectively used for waste cooking oil gasification to high quality syngas with a rather low content of tars.
... These reductants have different degrees of industrial success; however, all of them cause high levels of greenhouse gas emission [27]. Previous studies [28] report the use of organic substances to produce CO, H 2 , C and other gases, which are used as effective reducing agents of Fe 3 O 4 and other iron oxides. Therefore, green hydrogen could improve environmental performance and save costs in the smelter operation. ...
This study explores the use of green hydrogen as a flexible and environmentally-friendly energy vector in copper mining. The refining of copper sulphide ores involves several stages, such as comminution, froth flotation and smelting. The latter produces a higher concentration of copper through chemical transformations of copper sulphide ores. Reducing agents such as coal, coke, ferrosilicon and diesel are typically used in this step, but these reagents unfortunately have a considerable environmental footprint. The main goal of this work was therefore to perform a techno-economic analysis for methane production from the use of green hydrogen as a reducing agent for the smelting stage. The methodology involved the evaluation of the project based on a Net Present Value calculation and a sensitivity analysis of the main parameters which were performed using Oracle Crystal Ball software. The main results show a Net Present Value of 5.459 M USD and an 11.8-year pay-back. Multiparametric analysis shows that NPV is positive with 97.32% of confidence and that the main variable affecting the NPV is the methane price (contribution to variance of 97,8%). We conclude that the use of green hydrogen in copper smelting is a technically viable solution with economic and environmental benefits. The economic evaluation could be further improved with the incorporation of the heat and oxygen by-product, further reducing the CO2 emission.
... At the same time, many researchers have reused waste cooking oil in many ways. For instance, production of producer gas from waste cooking oil in a fluidized bed reactor [12], development of porous media burner operating on waste vegetable oil [13], chemical modification of waste cooking oil to improve the physical and rheological properties of asphalt binder [14] and so on. It can be seen that no researchers had added nanoparticles into the waste cooking oil and recycling it in the industry. ...
... Gasification is a useful thermochemical conversion process that generates syngas from low-rank fuels like coal, biomass, and waste [1,2]. In general, the product gas from a gasifier mostly contains combustible gases like H 2 , CO, CH 4 , and high-molecular-weight hydrocarbons (tar), along with pollutants such as H 2 S, COS, NH 3 , and HCl [3]. ...
Hot gas cleaning of producer gas generated from a gasification process has many advantages in terms of thermal efficiency, gas-quality improvement, compact gas-cleaning devices, and economic feasibility. In this study, the characteristics of molten tin as a working fluid for hot gas cleaning were examined. To evaluate the hot gas cleaning performance of molten tin, the producer gas generated from the gasification of empty fruit bunch pellets was tested with a molten-tin-based gas cleaning system connected to the downstream of the gasifier. Gas chromatographic analysis of the producer gas shows that the removal efficiencies of hydrogen sulfide and non-condensable tar were about 97% and 80%, respectively, in a molten tin bed maintained at 400 °C. The results suggest that molten tin could be used as a multifunctional gas-cleaning medium for the simultaneous removal of tar and hydrogen sulfide from the producer gas.
This paper reviews the renewable hydrogen generation pathways, along with purification and storage technologies, and discusses the hydrogen economy and future prospects from an Indian context.
Waste Motor Oil (WMO) has great potential to be utilized as a green fuel feedstock via thermochemical process as its high carbon content is suitable as alternative source during steam reforming reactions (SR). This process not only has potential for high syngas (CO and H2) production but also elimination of undesirable components, polyaromatic hydrocarbons (PAHs) and heavy metals in WMO. Here, evaluation of optimal conditions for WMO catalytic steam reforming in fixed-bed laboratory reactor to produce quality syngas was carried out. Influences of residence time (7–20 s), reaction temperature (700–900 °C), steam to carbon (S/C) ratio (1:2, 1:1, and 2:1), and Fe loadings (5% and 10%) on olivine support on carbon and hydrogen conversions were investigated. Results showed that the highest carbon and hydrogen conversions could be obtained after 10 s due to reactions achieving equilibrium. As for temperature, carbon and hydrogen conversions increased with temperature from mainly endothermic reactions which cause more hydrocarbon cracking. S/C volume ratio of 1:1 was preferable to obtain better carbon and hydrogen conversions due to superior heat distribution. Thus, the optimal conditions of WMO reforming were 10 s and S/C ratio of 1:1 at 800 °C which resulted in 94.68% and 79.34% carbon and hydrogen conversions, respectively, while gas product LHV was 4.44 MJ/m³. As for Fe loading on olivine, the best performance was acquired at 800 °C, residence time of 15 s, and S/C ratio of 1:1 with 10% Fe/olivine. Carbon and hydrogen conversions increased by 7.60% to 69.91% and by 13.70% to 69.31%, respectively, when compared to non-catalytic cases. This is because of higher cracking of heavy hydrocarbons from greater Fe active sites. Application of this work may lead to decrease in environmental impact from WMO disposal and make available the green fuel for sustainable power generations or as chemical intermediates in many industries.
One of the most challenging issues concerning the gasification of oil palm fronds (OPF) is the presence of tar and particulates formed during the process considering its high volatile matter content. In this study, a tar sampling train custom built based on standard tar sampling protocols was used to quantify the gravimetric concentration of tar (g/Nm(3)) in syngas produced from downdraft gasification of OPF. The amount of char, ash, and solid tar produced from the gasification process was measured in order to account for the mass and carbon conversion efficiency. Elemental analysis of the char and solid tar samples was done using ultimate analysis machine, while the relative concentration of the different compounds in the liquid tar was determined making use of a liquid gas chromatography (GC) unit. Average tar concentration of 4.928 g/Nm(3) and 1.923 g/Nm(3) was obtained for raw gas and cleaned gas samples, respectively. Tar concentration in the raw gas sample was found to be higher compared to results for other biomass materials, which could be attributed to the higher volatile matter percentage of OPF. Average cleaning efficiency of 61% which is comparable to that of sand bed filter and venturi scrubber cleaning systems reported in the literature was obtained for the cleaning system proposed in the current study.
Hydrogen is of great interest as the cleanest fuel for power generation using fuel cells and for transportation. Biomass can be thermochemically converted to hydrogen via two distinct strategies: (1) gasification followed by shift conversion, and (2) fast pyrolysis of biomass followed by catalytic steam reforming and shift conversion of specific fractions. This paper presents the latter route. The process begins with fast pyrolysis of biomass to produce bio-oil, which (as a whole or its selected fractions) can be converted to hydrogen via catalytic steam reforming followed by a shift conversion step. Such a process has been demonstrated at the bench scale using model compounds and the aqueous fraction of poplar oil with commercial nickel-based steam-reforming catalysts. Hydrogen yields as high as 85% of the stoichiometric value have been obtained. Initial catalyst activity can be maintained through periodic regeneration via steam or carbon dioxide (CO2) gasification of the carbonaceous deposits.
An experimental investigation of a downdraft biomass gasifier is carried out using furniture wood and wood chips. The effect of equivalence ratio on the gas composition, calorific value and the gas production rate is presented. The calorific value of the producer gas increases with equivalence ratio initially, attains a peak and then decreases with the increase in equivalence ratio. The gas flow rate per unit weight of the fuel increases linearly with equivalence ratio. It is also observed that complete conversion of carbon to gaseous fuel has not taken place even for the optimum equivalence ratio.
Bio fuel oil combustion experiments were successfully demonstrated at the 75 MWe oil-fired power plant without major equipment retrofit and 100% bio-fuel oil combustion was possible without big problems. The experimental data error correction was conducted and numerical model-based analysis technique was applied for the evaluation of the results. Incase of bio fuel oil combustion, heat absorption of radiative heat transfer section was reduced while convection section has opposite trend. The furnace exit gas temperature tends to rise slightly. Environment emissions such as NOx and SOx concentrations showed a tendency to decrease during the bio fuel oil combustion period. On the other hand, boiler efficiency was slightly underestimated.
Waste cooking oil to biodiesel conversion efficiency depends on the recycling mode that is being practiced. The recycling modes in China, the US and Japan can be placed in two categories: third party take-back (TPT) and the biodiesel enterprise take-back (BET). We review the operation mechanisms of theses modes, their advantages and disadvantages in three countries and compare them using recycling costs and profits of biodiesel enterprises, subsidies for manufacturers, recycling rates, degree of administrative control, technical support and incentive mechanisms provided for the restaurants. We find that the TPT mode practiced in Japan and the US is superior to the BET mode due to the subsidies provided for biodiesel enterprises and the implementation of strict regulation policies in place for the restaurants. In China, Suzhou and Ningbo cases may have better resource recovery effect than the TPT mode practiced elsewhere, if further enhanced. Finally, we provide suggestions for improving waste oil to biodiesel conversion in China.
The black liquor gasification based bio-fuel production at chemical pulp mill is an attractive option to replace conventional recovery boilers increasing system energy efficiency. The present paper studies circulating fluidized bed system with direct causticization using TiO2 for the gasification of the black liquor to the synthesis gas. The advantage of using direct causticization is the elimination of energy-intensive lime kiln which is an integral part of the conventional black liquor recovery system. The study evaluates the effects of gasifying medium i.e. oxygen or air, on the fluidized bed gasification system, the synthesis gas composition, and the downstream processes for the synthesis gas conversion to the synthetic natural gas (SNG). The results showed higher synthetic natural gas production potential with about 10% higher energy efficiency using oxygen blown gasification system than the air blown system. From the pulp mill integration perspective, the material and energy balance results in better integration of air blown system than the oxygen blown system, e.g. less steam required to be generated in the power boiler, less electricity import, and less additional biomass requirement. However, the air blown system still requires a significant amount of energy in terms of the synthesis gas handling and gas upgrading using the nitrogen rejection system.
A model is proposed to describe soot formation and oxidation during bio-oil gasification. It is based on the description of bio-oil heating, devolatilization, reforming of gases and conversion of both char and soot solids. Detailed chemistry (159 species and 773 reactions) is used in the gas phase. Soot production is described by a single reaction based on C2H2 species concentration and three heterogeneous soot oxidation reactions. To support the validation of the model, three sets of experiments were carried out in a lab-scale Entrained Flow Reactor (EFR) equipped with soot quantification device. The temperature was varied from 1000 to 1400 °C and three gaseous atmospheres were considered: default of steam, large excess of steam (H2O/C = 8), and the presence of oxygen in the O/C range of 0.075–0.5. The model is shown to accurately describe the evolution of the concentration of the main gas species and to satisfactorily describe the soot concentration under the three atmospheres using a single set of identified kinetic parameters. Thanks to this model the contribution of different mechanisms involved in soot formation and oxidation in various situations can be assessed.
The process of bio-oil pyrolysis/gasification and gas evolution characteristic was studied using a thermogravimetric analyzer coupled with Fourier transform infrared spectroscopy (TG-FTIR). Pyrolysis/gasification of bio-oil and its fractions were also performed in a fixed bed. As a result, the process of bio-oil pyrolysis/gasification can be divided into two stages. The first is volatilization and pyrolysis of the light compounds at low temperature and the second is cracking and polymerization of the heavy compounds at high temperature. The values of activation energy are 35–38 kJ/mol in the first stage and 15–22 kJ/mol in the second stage, respectively. With temperature increasing, the conversion of pyrolysis/gasification grows higher and the yield of synthesis gas (syngas) increases. However, the calorific value of the gas has an inverse correlation with the temperature. In comparison, the light fraction (LF) makes more contribution to the overall H2 release; while CO and CH4 are mainly generated from the heavy fraction (HF).
Hydrogen production was prepared via catalytic steam reforming of fast pyrolysis bio-oil in a two-stage fixed bed reactor system. Low-cost catalyst dolomite was chosen for the primary steam reforming of bio-oil in consideration of the unavoidable deactivation caused by direct contact of metal catalyst and bio-oil itself. Nickel-based catalyst Ni/MgO was used in the second stage to increase the purity and the yield of desirable gas product further. Influential parameters such as temperature, steam to carbon ratio (S/C, S/CH4), and material space velocity (WBHSV, GHSV) both for the first and the second reaction stages on gas product yield, carbon selectivity of gas product, CH4 conversion as well as purity of desirable gas product were investigated. High temperature (> 850 °C) and high S/C (> 12) are necessary for efficient conversion of bio-oil to desirable gas product in the first steam reforming stage. Low WBHSV favors the increase of any gas product yield at any selected temperature and the overall conversion of bio-oil to gas product increases accordingly. Nickel-based catalyst Ni/MgO is effective in purification stage and 100% conversion of CH4 can be obtained under the conditions of S/CH4 no less than 2 and temperature no less than 800 °C. Low GHSV favors the CH4 conversion and the maximum CH4 conversion 100%, desirable gas product purity 100%, and potential hydrogen yield 81.1% can be obtained at 800 °C provided that GHSV is no more than 3600 h− 1. Carbon deposition behaviors in one-stage reactor prove that the steam reforming of crude bio-oil in a two-stage fixed bed reaction system is necessary and significant.
A novel technology to mitigate the climate changes and improve energy security is Pressurized Entrained flow High Temperature Black Liquor Gasification (PEHT-BLG) in combination with an efficient fuel synthesis using the resulting syngas. In order to optimise the technology for use in a pulp and paper mill based biorefinery, it is of great importance to understand how the operational parameters of the gasifier affect the product gas composition. The present paper is based on experiments where gas samples were withdrawn from the hot part of a 3 MW entrained flow pressurized black liquor gasifier of semi industrial scale using a high temperature gas sampling system. Specifically, the influence of process conditions on product gas composition (CO2, CO, H2, CH4, H2S, and COS) were examined by systematically varying the operational parameters: system pressure, oxygen to black liquor equivalence ratio, black liquor flow rate to pressure ratio and black liquor pre-heat temperature. Due to the harsh environment inside the gasification reactor, gas sampling is a challenging task. However, for the purpose of the current study, a specially designed high temperature gas sampling system was successfully developed and used. The results, obtained from two separate experimental campaigns, show that all of the investigated operational parameters have a significant influence on the product gas composition and present valuable information about to the process characteristics.
Experiments were carried out with a woody waste fraction using a two-stage gasifier consisting of a fluidized bed zone and a tar cracking zone that was filled with activated carbon. In the experiments, the effects of experimental conditions such as the temperature and the equivalence ratio were investigated. In addition, the results of the experiments with virgin activated carbon, without activated carbon, and with spent activated carbon were compared. The producer gases that were obtained in the experiments were analyzed using GCs (FID and TCD) and a GC–MS system. The producer gas obtained with the application of activated carbon at an ER of 0.2 had high H2 content (16vol.%, N2-free), and its lower heating value was above 10MJ/Nm3. In addition, the total amount of the tar captured by the scrubbers and the electrostatic precipitator was reduced sixfold when activated carbon was applied.
Gasification of pyrolysis oil was studied in a fluidized bed over a wide temperature range (523−914 °C) with and without the use of nickel-based catalysts. Noncatalytically, a typical fuel gas was produced. Both a special designed fluid bed catalyst and a crushed commercial fixed bed catalyst showed an initial activity for syngas (H2 and CO) production at T > 700 °C. However, these catalysts lost activity irreversibly and elutriation from the fluid bed occurred. The equilibrium catalytic activity suffered from incomplete reforming of hydrocarbons (CH4). In all the experiments the carbon to gas conversion was incomplete, which was mainly caused by the formation of deposits and the slip of microcarbonaceous particles. A two-stage reactor concept, which consisted of a sand fluidized bed followed by a fixed catalytic bed, was proposed and tested. This system uncouples the atomization/cracking of the oil and the catalytic conditioning of the produced gases, enabling protection of the catalyst and creating opportunities for energy efficiency improvements. In a bench scale unit of this reactor (0.5 kg oil/h), methane and C2−C3 free syngas (2.1 Nm3 CO + H2/kg dry oil, H2/CO = 2.6) with a low tar content (0.2 g/Nm3; dry, N2 free gas) was produced in a long duration test (11 h).
Bio-oil reforming to produce hydrogen could be an attractive option for sustainable hydrogen. Hydrogen production via catalytic steam reforming of bio-oil in a fluidized-bed reactor was studied in this paper. The optimum conditions on hydrogen production were obtained at 700 °C, steam/carbon mole ratio (S/C) of 17, and weight hourly space velocity (WHSV) of 0.4 h−1. In addition, the reason for catalyst deactivation in a fluidized-bed reactor was investigated. The fresh and deactivation catalysts were analyzed by X-ray diffraction (XRD), Brunauer−Emmett−Teller (BET), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM), which showed that the carbon deposition is not the main reason for catalyst deactivation. The main reason for fresh catalyst deactivation was the NiO grain sintered on the supporter surface.
Bio-oil/char mixtures and whole bio-oil from rapid pyrolysis of woody biomass are potential feeds for synthesis gas production via steam gasification. A 7.8 cm diameter, atmospheric pressure, fluid bed gasifier was constructed and operated with either a nickel-containing steam reforming catalyst or silica sand as bed material. Both bio-oil and a slurry of 80 wt % bio-oil and 20 wt % char were tested as feedstocks. Effects of bed temperature, steam to carbon molar ratio, and space velocity on gaseous component yields and carbon conversion are reported for both feedstocks using catalytic and noncatalytic bed material. At the moderate temperatures (<840 °C) of the experiments, carbon conversion is incomplete, and some mixed hydrocarbons are present in the produced gases. Yields of the main gas constituents are compared with an equilibrium model which was modified to correct for these two factors. Observations are made on stability and attrition issues with the catalyst.
Hydrogen produced from renewable energy sources is of great interest as an alternative to fossil fuels and as a means for power generation via fuel cells. The aqueous fraction of bio-oil can be effectively reformed to hydrogen-rich streams in the presence of active catalytic materials. In this paper, we present the experimental work carried out in a fixed bed reactor for the reforming of bio-oil. The performance of the reactor was studied at various conditions and compared to the values theoretically predicted by thermodynamic equilibrium. The effect of reaction temperature, steam-to-carbon ratio in the feed, and space velocity was investigated in the presence of a commercial nickel catalyst. Runs were conducted with acetic acid, acetone, and ethylene glycol, representative model compounds of bio-oil, and the aqueous phase of a real bio-oil derived from beech wood. The results of the selected model compounds show that all can be effectively reformed with hydrogen yields up to 90% at reaction temperatures higher than 600 °C and steam-to-carbon ratios higher than 3. The reforming of the aqueous fraction of bio-oil proved to be more difficult, with the hydrogen yield fluctuating at about 60%. The most serious problem encountered in these experiments is coking. The formation of carbonaceous deposits in the upper part of the catalyst zone limits the reforming time and necessitates frequent regeneration of the catalyst.
It has been shown that thermal oxidation of corn oil at 200°C. caused the formation of polymeric material. A combination of
urea fractionation and molecular distillation was employed to concentrate the polymeric material. Further fractionation of
the polymer concentrates was performed with the aid of solvent-extraction procedures. These procedures resulted in the isolation
of several polymer fractions with molecular weights ranging from 692 to 1,600. Analyses of the fractions indicated that they
were of high oxygen content and that they contained unsaturation, difficult to remove by hydrogenation. The oxygen present
in the fractions was shown to be in the form of hydroxyl and carboxyl groups. The polymeric materials could be linked together
in a noncyclic structure.
The catalytic steam gasification of palm oil wastes for hydrogen-rich gas production was experimentally investigated in a combined fixed bed reactor using the newly developed tri-metallic catalyst. The results indicated that the supported tri-metallic catalyst had greater activity for the cracking of hydrocarbons and tar in vapor phase and higher hydrogen yield than the calcined dolomite in catalytic steam gasification of palm oil wastes. A series of experiments have been performed to explore the effects of temperature, steam to biomass ratio (S/B) and biomass particle size on gas composition, gas yield, low heating value (LHV) and hydrogen yield. The experiments demonstrated that temperature was the most important factor in this process; higher temperature contributed to higher hydrogen production and gas yield, however, it lowered gas heating value. Comparing with biomass catalytic gasification, the introduction of steam improved gas quality and yield, the optimal value of S/B was found to be 1.33 under the present operating condition. It was also shown that a smaller particle size was more favorable for gas quality and yield. However, the LHV of fuel gas decreased with the increasing S/B ratio and the decreasing biomass particle size.
Edible oil wastes (EOW) are generally used in the production of soap and/or disposed in waste water treatment stations. In Europe, their use for energy is almost exclusively for the production of biodiesel. However, the nature and quality of EOW may turn their use for biodiesel not always suitable. Therefore, for environmental reasons, it is important to investigate other options like co-gasification with coal. Gasification is generally considered more environmentally friendly and its impact is considerably less polluting than other thermochemical processes. Co-gasification requires that synergy exists between coal and EOW to take profit of their complementary advantages. Co-gasification runs were undertaken on a bench-scale atmospheric fluidised bed gasifier, using both steam and air-steam mixtures as gasification medium. Operating conditions like gasification temperature, steam/air ratio and oil content in feedstock blends were varied to check their effect with the aim of optimising the gasification process. Some difficulties in feeding the blend of coal with EOW were observed when the oil content increased, which also raised hydrocarbons content in the gas produced. Both the rise of temperature and of air flow rate allowed lower tars and gaseous hydrocarbons concentrations. Higher gas yields were obtained at higher gasification temperatures, the gas being richer in hydrogen content at the expense of hydrocarbons. Solid residues (ashes and char) produced by gasification of blends of coal and EOW were also analysed to understand their nature and to evaluate their impact on the environment.
Gas cleaning for tar and particle removal is necessary for internal combustion (IC) engine applications of producer gas from fixed bed biomass gasifiers which are usually in the capacity range from 100 kW up to 5000 kW. In the present investigation, tar and particle collection efficiencies have been determined in a sand bed filter, a wash tower, two different fabric filters, and a rotational particle separator (RPS) in different test runs with fixed bed gasifiers. Tar adsorption on coke has been investigated in a fixed bed batch reactor. Furthermore data from literature for catalytic tar crackers, venturi scrubbers, a rotational atomizer, and a wet electrostatic precipitator (ESP) are given. Based on the presented gas cleaning efficiencies and the investment cost, an assessment of gas cleaning systems is made for IC engine applications from cocurrent gasifiers. The results show that the postulated gas quality requirements for IC engines cannot be safely achieved with state-of-the-art gas cleaning techniques and that 90% particle removal is easier to achieve than 90% tar removal. Except for the catalytic tar crackers which are considered as an option for applications above several MW and for gases with a high tar level, none of the investigated gas cleaning systems can securely meet a tar reduction exceeding 90%. Therefore one of the key issues for a successful application of biomass derived producer gas from small scale gasifiers is the tar removal, where further development is needed.
Catalytic gasification of waste motor oil (MO) for the generation of high purity of hydrogen and then integrated to a proton exchange membrane fuel cell (PEMFC) is economically and environmentally attractive. Thus, the objective of the present work was to investigate a MO catalytic gasification for generating high-purity hydrogen with 15 wt.% NiO/Al2O3 catalysts. In a tab-scale fixed-bed downdraft experimental approach, catalytic gasification of MO was accompanied by a substantial production of syngas at 760-900 K. From the XANES spectra, most of the Ni(II) reduced to Ni(0) was found in the MO catalytic gasification process. The EXAFS data also showed that the central Ni atoms have a Ni-O and a Ni-Ni with bond distances of 2.04 +/- 0.05 angstrom and 2.48 +/- 0.05 angstrom. respectively. In addition to over 85% of syngas generation, approximately 8.35 x 10(5) kcal h(-1) of thermal energy was recovered and cold gas efficiency (CGE) was 77-84% when the catalytic gasifier was operated at O/C atomic ratios between 1.1 and 1.3. The proposed syngas production unit can be integrated in a fuel processor (e.g. PEMFC), in order to separate and purify the syngas to yield a 99.99% hydrogen stream. Moreover, cost or benefit analyses of MO catalytic gasifiers of 10-and 20-TPD (tons per day) were also performed.
Biodiesel co-firing – field demonstration results. Final report, Electric Power Research Institute
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Fuel supply plan for transportation with biodiesel Gyeonggi Research Institute
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Lee JI. Fuel supply plan for transportation with biodiesel. Gyeonggi Research Institute; December 2010. <http://gri.re.kr/korea/jsp/policy/gri_view.jsp?idx= 2931:3551&go=15&gogroup=>.
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Biodiesel co-firing -field demonstration results
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Facchiano A. Biodiesel co-firing -field demonstration results. Final report,
Electric Power Research Institute; April 2007.
Fuel supply plan for transportation with biodiesel
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Lee JI. Fuel supply plan for transportation with biodiesel. Gyeonggi Research
Institute; December 2010. <http://gri.re.kr/korea/jsp/policy/gri_view.jsp?idx=
2931:3551&go=15&gogroup=>.
System analysis of dry black liquor gasification based synthetic gas production comparing oxygen and air blown gasification systems
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