Fixed-bed Gasification Process Research Articles

CO2 energy vector in the concept of circular energy

The paper analyzes the conversion of the carbon dioxide (CO2) through recovery and storage into an energy production vector by transforming it into methanol (CH3OH) and carbon monoxide (CO). These gaseous components can produce energy by combustion, and the resulting carbon dioxide is reintroduced into the capture and storage circuit. This type of carbon dioxide transformation into an energy vector in a circular energy system will contribute to the elimination or to the significant reduction of its long-term storage in caves or under the sea water. By eliminating storage, the costs will be significantly reduced, as well as the environmental pollution. The paper considers the methanol use in residential heating instead of liquid hydrocarbons, especially for isolated areas or without a natural gas network, and also in the internal combustion engines in transport, agriculture and construction. The first direction of the research included an experimental phase that involved using a 55kW boiler for medium-sized residential heating. The second direction analyzed the transformation of CO2 into CO (fuel gas) through gasification technology. For this transformation, the fixed bed gasification process was considered. The carbon monoxide can be used in a pure state or mixed with methane or other combustible gases, both in power plants and in internal combustion engines. The current significant results in the methanol production field enables CO2 to become an energy vector, instead of a gas with zero potential and expensive to store. Thus, the research can significantly contribute to the development of power engineering as a circular application in the context of circular economy.

Experimental Analysis of Four Agricultural Biomass Fuel (Wood Charcoal, Maize Straws, Palm Kernel Sawdust and Rice Husks) Subjected to Fixed Bed Gasification Process

The production of syngas from gasification is a heathy way to convert agricultural residues into energy. In fact the gasification characteristics, konwn as the temperature and the plasma duration, were assessed. The gasification process consisted in introducing into a designed updraft gasifier four types of biomass (maize, rice husks, charcoal and kernel palm) of a well known quantity (2, 4, 6, 8, and 10 kgs). The biomass choice was done because of their abundance and they can assure the renewal of resources in an industrial project setting. Air used as a gasifying agent, was introduced in the gasifier through a control valve. Air supply in the gas producer to favor the biomass conversion was done using a fan of 12 Volts turned by photovoltaic solar panels of 100 W each. The main results of this study were as follows. Whatever the quantity of biomass used, the highest gasification temperature was recorded with the charcoal followed by the palm kernel. The plasma or flame duration was the highest during the gasification of 10 kgs of charcoal followed by the palm kernel. The palm kernel and the maize straws are more advisable for the gasification purpose in rural areas of Cameroon.

Analysis of biochars produced from the gasification of Pinus patula pellets and chips as soil amendments

In this work, biochar (BC), a co-product of the fixed bed gasification process of Pinus patula wood pellets (PL) and chips (CH), was characterized as soil amendment. The physicochemical properties and the mineral content of the pellet’s biochar (PL-BC) and the chips biochar (CH-BC) were analyzed following the NTC5167 Colombian technical standard. The BET surface area values of the BCs were 367,33 m2/g and 233,56 m2/g for the PL-BC and the CH-BC, respectively, and the pore volume was 0,20 cm3/g for the PL-BC and 0,13 cm3/g for the CH-BC. These characteristics favor the increase of the BCs water-holding capacity (WHC). Properties such as the pH (8,8-9,0), the WHC (219 %-186,4 %), the total organic carbon (33,8 %-23,9 %), the metalloid presence (Ca, Mg, K, Mn, Al, Si, and Fe), and the ash (1,92wt % - 2,74 wt %) and moisture contents (11,13wt %-11,63 wt %) for both BCs were found to be within the limits set by the standard. Furthermore, the presence of micro and macronutrients, such as Fe and phosphorus (P), and the alkaline pH, make possible the use of these BCs as amendments for acid soils.

Simulation of thermochemical processes in Aspen Plus as a tool for biorefinery analysis

The development of tools for the synthesis, design, and optimization of biorefineries requires deep knowledge of the thermochemical processes involved in these schemes. For this project, three models from scientific literature were implemented to simulate the processes: fast pyrolysis in a fluidized bed, fixed-bed, and fluidized-bed gasification using the Aspen PlusTM software. These models allow the user to obtain performance, consumption, and cost parameters necessary for the design and optimization of biorefineries schemes. The fast pyrolysis model encompasses a detailed description of biomass decomposition and kinetics of the process (149 reactions). In the fixed-bed gasification process, seven reactions that model the process have been integrated into two equilibrium reactors that minimize the Gibbs free energy. The model used for fluidized bed gasification considers both hydrodynamic and kinetic parameters, as well as a kinetic model that considers the change in the combustion reaction rate of biomass with oxygen leading to a change in temperature. Due to the complexity and detail of all these models, it was necessary to use FORTRAN subroutines and iterative Excel macros linked to Aspen PlusTM. Finally, the results of each simulation were validated with data from the model sources, as well as experimental results from the literature.

Modeling and simulation of a fixed bed gasification process for thermal treatment of municipal solid waste and agricultural residues

This work aims to develop a numerical simulation model of the combined and integrated production process of combustion and gasification, for a synthesis gas production system (SYNGAS), fed with municipal solid waste (MSW), agricultural and forestry waste. For this purpose, the EMSO software (Environment for Modeling, Simulation, and Optimization) was used in the formulation of a fixed-bed gasifier with the co-current flow. The model is developed based on mathematical calculations of partial differential equations, being one-dimensional (1-D), and considers chemical kinetics, diffusivity, and heat and mass transfer phenomena. Its validation is based on data available in the literature (variables, initial and operational conditions). As a result, a simulation of a gasifier was obtained, capable of predicting the production of Syngas, having a good correlation with the published experimental results. The general data obtained were in agreement, with high consistency for the analysis of the pilot plant in the laboratory and semi-industrial scale for solid waste processing. However, detailing the behavior of the gasifier is essential to maximize the efficiency of the process. For that, the numerical simulation tested several operational parameters, such as air–fuel ratio and gasifier temperature for instance.

Composition of phenolic compounds in wastewater from the fixed-bed gasification of Baishihu coal

Crude phenols extracted using organic solvent from the wastewater of a typical fixed-bed gasification process was used as a raw material, and the distillation range was analyzed. The wide and narrow fractions of the raw material derived from distillation range analysis were cut using a real boiling point distillation device. The phenolic compounds in the different fractions were then qualitatively and quantitatively analyzed by gas chromatography after derivatization pretreatment. The yield of the < 290 °C fraction was 68.50% (mass fraction). A total of 33 effective phenolic compounds were identified in this fraction, and the percentage of identified phenols was nearly 80%. The contents of eight phenolic compounds were high, with phenol being the most abundant (26.34%) followed by catechol (13.44%). The contents of the remaining six abundant phenols ranged from 4% to 8%. The sum of the contents of m-cresol and p-cresol exceeded 12%, and the content of 5-indenol was nearly 8%. The yield of the fraction rich in low-grade phenols (< 230 °C) was 35.40%. The content of phenol in this fraction was more than 40%, the total content of cresol was over 23%, and the total content of m-cresol and p-cresol was nearly 20%. At room temperature, the 235–245 °C and 245–260 °C fractions were white crystals in which the catechol content was approximately 50%, and the 5-indenol content was more than 10%. The contents of these two high-value-added phenolic compounds are low in typical coal tar, making them difficult to extract. However, due to their strong polarity and good water solubility, catechol and 5-indenol are enriched in gasification wastewater by water selection, allowing their further extraction.

Development of a Chemical Equilibrium Model of the Downdraft Fixed Bed Gasification Process with known Product Temperature, Using air as an Oxidizing Agent

A chemical equilibrium model for known outlet temperature of the products was carried out on a downdraft fixed bed gasifier. Biomass from oil palm kernel is used with proximate and ultimate analysis; the general gasification reaction takes into account the biomass moisture, the reaction products are formed by CH4, H2O, N2, CO, CO2 and H2. The model is described in detail and the equations are solved using the EES software. The model shows the results obtained for temperature ranges from 500 K to 1500 K and 1.0 atm. The model is validated by direct comparison of the gas composition with the results reported in the literature for similar conditions, obtaining favorable results.

Experimental Gasification of Coffee Husk Using Pure Oxygen-Steam Blends

This work discusses results on temperature profile, syngas composition, High Heating Value, and efficiency of a Coffee Husk counter-current fixed-bed gasification process, in which oxygen-steam blends were used as oxidizing agent. The experimentation was carried out for various Equivalence Ratio (ER) and Steam-Fuel Ratio (SF), whose ranges were [1.6 – 5.6] and [0.4 – 0.8] respectively. The results show that Increased steam (higher steam fuel ratios) improves the H2/CO molar ratio i.e., for a constant ER=3.7 and SF at 0.4, 0.6, and 0.8, the H2/CO ratio was 1.2, 1.4, and 1.8 respectively. Also, the addition of steam tends to increase the syngas Higher Heating Value, which ranged between 7714 kJ/m3 at ER = 1.6 and SF = 0.4 and 8841 kJ/m3 at ER = 3.2 and SF = 0.8. On the other hand, increased ER (lower oxygen) decreases the Net Cold Gasification Efficiency (CGENET) which was between 53 % at ER = 5.6 and SF = 0.6 and 82 % at ER = 1.6 and SF = 0.4. Results were also compared to results published before for gasification of the same biomass but using air-steam mixtures for partial oxidation. This comparison shows that the use of oxygen increases both the temperature profile in the bed and the yield of CO and H2 contained in the syngas.

Thermodynamic assessment of the fixed-bed downdraft gasification process of fallen leaves pelletized with glycerol as binder

In this work, the effect of airflow rate and glycerol content of pelletized fallen leaves (FL) on a fixed bed gasification process is studied. FLs were collected in the main campus of the University of Antioquia (Medellin, Colombia). Levels of airflow rate tested were 0.075, 0.150, and 0.225 kg/s/m2; and the glycerol content of pellets evaluated were 0 and 5%wt. When the airflow rate increased, flame front velocity increased up to 51.3%. This behavior was attributed to high temperatures in the reaction front, which were favored by the decrease of fuel-air equivalence ratio leading to high biomass consumption in the gasification process. Regarding the glycerol content of the pellets, production of gaseous species was favored with this compound, where an increase of CH4 by 25% and H2 by 20% was observed with regard to the raw pellets. The high concentration of the gaseous fuel species leads to an increase of cold gas efficiency (CGE) as well as chemical exergy efficiency (CEE) by ∼13%. Whereas, the irreversibilities (I) of the thermochemical process decreased by 10% when pellets with glycerol content were gasified.

Numerical analysis of wood biomass packing factor in a fixed-bed gasification process

Abstract The biomass gasification process in fixed bed was studied by means of computational fluid dynamics (CFD) numerical analysis. The aim was to evaluate the effect of the biomass packing factor on the thermochemical process. The fuel-wood used was Jacaranda Copaia in various shapes: chips, cylinders, and cubes with packing factors (PF) of 0.38, 0.48, and 0.59, respectively. The mathematical model is a transient 2D CFD model, which was developed through the implementation of User Defined Functions in ANSYS-Fluent. The model was extended to simulate the gasification process by expanding the chemical kinetic mechanism and by adapting the stages of pyrolysis, oxidation, and reduction. The model was validated with experimental data. The average relative error between experimental and numerical data was 5.45%. By means of the sensitivity analysis, it was found that with an increase in the packing factor from 0.38 to 0.59, the absorption of radiative heat transfer increases by 27% leading to increase the solid temperature in the reaction front, but due to a lower penetration of radiation, the drying and pyrolysis reaction rates decrease. But nevertheless, the higher solid temperature with packing factor favors the convective solid-gas heat transfer in the drying stage.

Experimental activities on Sotacarbo 5 MWth gasification demonstration plant

In the field of coal and biomass gasification for distributed power generation, ENEA and Sotacarbo are developing several activities on demonstration plant scale in order to test gasification technologies for combined production of synthesis gas and electric power in medium and small-scale industrial plants.The Sotacarbo pilot platform has been built up to test different plant solutions at different operating conditions; therefore, a very flexible and simple layout has been designed and constructed. Both demonstration and pilot plants are based on an up-draft, air-blown and fixed-bed gasification process, suitable to be fed with both coal and wood chips.In particular, the demonstration unit of the plant platform includes a 5MWth gasifier equipped with a wet scrubber for syngas clean up in equicurrent conditions and a flare.This presentation reports some results of the experimental activities related to the start-up of coal and biomass gasification carried out on a demonstration plant at Sotacarbo Research Centre in the South-West of Sardinia (Italy). The aim is to assess the system behaviour and to evaluate the gasification performance. The experimental activity was carried out in order to check the operability of all components and to improve the knowledge of gasifier operation in the different phase of start-up, run and shut down. A characterization of the process was performed and the modalities and key parameters to achieve standard operating conditions were identified. The ultimate aim is to provide useful data so as to improve the system efficiency and to make electricity generation suitable by an internal combustion engine fed by clean syngas. In particular, during the experimental tests different types of fuel were tested: wood chips, Colombian coal, blends of Colombian coal and wood chips. A steady-state simulation model of the gasification process has been developed in the Aspen Plus v.8 simulation environment. The experimental data were used for a first tuning of the model. The validating activity is still going on with newer experimental data. The aim is to realise a model of the plant able to predicts syngas composition, heating value, cold gas efficiency (CGE) and performance at different operating conditions. The model will be a useful tool for future experimental activities.

Experimental analysis of the fixed bed gasification process of the mixtures of the chicken manure with biomass

The increasing worldwide demand for poultry, mainly chickens, has resulted in a growing generation of poultry derived wastes. Among many types of biomass, the animal waste, including poultry manure, can have a significant potential for application in the energy industry. In this work, the proposal of thermal utilization of the chicken manure was given. The laboratory scale research on co-gasification chicken manure with wood pellets has been carried out in a fixed bed gasifier of capacity 5 kg/h. The experiments were done for two types of fuel blends. In the first experiment stage wood pellets were mixed with a raw, pre-dried chicken manure. Another part of test concerned gasification of blends of pelletized chicken manure and wood pellets.The main goal of the experiments was to determine the influence of the addition of dried chicken manure to the wood pellet feedstock on the gasification process as well as on physicochemical properties of generated syngas.The results of the gasification tests confirm that co-gasification of the chicken manure with wood biomass can be a promising proposal for the utilization of a poultry derived wastes. Gasification of a chicken manure provides generation of combustible syngas with the lower heating value LHV equal to 2.0 MJ/m3 in case of a raw, pre-dried chicken manure and 2.7 MJ/m3 in case of chicken manure pellets. Increasing share of woody biomass in the feedstock significantly increases the calorific value of the syngas. Different physical properties of the feedstock components (fraction and ash content) require further research to define reactor suitable for co-gasification of analyzed fuel blends.

Mathematical Modelling of the Fixed-Bed Biomass-Coal Co-Gasification Process

The paper considers mathematical modelling of downdraft fixed-bed gasification process of the mixtures of woody biomass and coal. Biomass/coal ratio, biomass moisture content and air equivalence ratio are varying parameters. Boundaries of the efficient gasification regimes are estimated.

Simulation Research on the Fixed-Bed Gasification Process in a Two-Stage Combined Gasifier

The novel two-stage gasification process that is combined entrained-flow for first stage and fixed-bed for second stage was shown in the study. The benefit of the second stage was to recycle the sensible heat from first stage syngas and enhance the energy utilization. The fixed-bed gasification reaction of second stage was individually investigated by numerical simulation. The simulated results were validated well with the experimental data in terms of gas concentration, gas flow rate, and carbon conversion. The distributions of velocity, temperature, gas concentration, solid mass fraction, and carbon conversion during the gasification process were analyzed. The influences of coal amount and particle size in the second stage on gasification reactivity were also discussed in the study. Results showed that the gas temperature was reduced and the effective gas concentration increased when first stage syngas flowing through the second stage coal layer. The increase of coal amount of second stage showed a more significant heat recovery, but the heating rate and ultimate carbon conversion would be reduced. The increase of particle size resulted in the decreasing of effective gas concentration and gas–solid reaction rate, which was attributed to the change of specific surface area and the increase heat transfer resistance from the particle surface to inside.

High temperature air-blown gasification of Korean anthracite and plastic waste mixture

Korean anthracite is too high in ash contents and low in calorific value to be used as an industrial energy source, the demand for anthracite has rapidly decreased and its competitiveness weakened. To overcome the problem, a mixture of Korean anthracite and plastic wastes low in ash and high in calorific value was manufactured. A 1.0T/D fixed bed gasification process was developed to understand the gasification characteristics of the mixtures and secure operation technology using Korean and Chinese anthracite. For the Korean anthracite, the syngas composition and heating value are varied from 10 to 20% and from 300 to 800 kcal/Nm3 as a function of steam/air/fuel ratio. Therefore, it is concluded that Korean anthracite is hard to gasify because of low reactivity. For the Chinese anthracite low ash content and higher heating value than domestic anthracite, the syngas composition was maintained at about 20–40% and the calorific value was 800–1,300 kcal/Nm3. A reformer using high-temperature air/steam was installed just after the gasifier to combust and convert tar and soot into syngas. We confirmed that the amount of generated tar and soot showed a salient difference after running the reformer. In the future, gasification experiments of manufactured mixtures of anthracite and plastic waste using 1.0T/D fixed bed gasifier will be performed.

96/00241 Repowering applications using the British Gas/Lurgi fixed-bed gasification process

96/00241 Repowering applications using the British Gas/Lurgi fixed-bed gasification process

95/00314 Application of the British Gas/Lurgi fixed-bed gasification process in the U.S. DOE clean coal five program

95/00314 Application of the British Gas/Lurgi fixed-bed gasification process in the U.S. DOE clean coal five program