Product Gas Composition Research Articles

Experimental research on hydrogen-rich syngas yield by catalytic biomass air-gasification over Ni/olivine as in-situ tar destruction catalyst

This research focuses on investigating the air-gasification process of pine sawdust using a fluidized bed unit with Ni/olivine as an in-situ tar destruction catalyst. The goal is to eliminate tar production and obtain high-quality synthesis gas. Consequently, the effects of reaction conditions and catalyst properties on the producer gas composition, the lower heating value (LHV) of the yielded synthesis gas (syngas), char conversion efficiency (CCE), and cold gas efficiency (GE) are comprehensively explored. The conclusions indicate that higher temperatures favor the H2 and CO production and result in an evident decrease of CH4 and C2H4, which is responsible for the increasing gas LHV. The tar capture efficiency (TCE) increases by increasing the equivalence ratio (ER); however, a reverse trend obtains for gas LHV because of a significant decline in the combustible gas contents. The results also reveal that when using Ni/olivine as the bed material, GE reaches an optimum value of 72.4% at equivalence ratio (ER) of 0.21 and then lowers down with a further increase in ER to 0.39 due to the enhanced char combustion reaction. The tar yield (1.3–6.8 g/Nm3) significantly decreases with temperature, whereas H2 concentration (14.1–29.8 vol %), CCE (51.3–89.1%), GE (44.8–86.1%) and gas LHV (5.13–7.19 MJ/Nm3) promote at high temperature. Compared to raw-olivine, the lower heating value (LHV) of the producer gas slightly increases under the same conditions (T = 800 °C and ER = 0.21) when the bed material is Ni/olivine. The conclusions obtained help to provide reliable theoretical guidance for operating condition optimization of biomass catalytic air-gasification with Ni/olivine as bed material in a fluidized bed reactor.

Air gasification of high-ash solid waste in a pilot-scale downdraft gasifier: Experimental and numerical analysis

The present work investigates the effect of process parameters on the gasification potential of high-ash solid wastes in a downdraft gasifier using experimental and simulation studies. The air gasification of lignocellulosic garden waste was conducted in a lab-scale fixed bed reactor for the equivalence ratio range of 0.25–0.39. An exhaustive model was devised in Aspen Plus process simulator incorporating the parametric geometry of the gasifier and comprehensive gasification kinetics. Furthermore, the developed model was validated using the experimental results and a fair agreement was obtained. Both the experimental and simulation studies affirmed that the maximum gasification efficiency was obtained at an equivalence ratio of around 0.32. Sensitivity analysis was conducted to scrutinize the effect of critical process parameters on output parameters such as producer gas composition, lower heating value, carbon conversion efficiency, and system's cold gas efficiency. This modeling approach provides valuable insight for generating producer gas from low-grade biomass by optimizing the operating parameters of the downdraft gasifiers. This research can also assist as a guide for stakeholders in renewable energy, waste to energy, and environmentally friendly technologies.

Kinetic and thermodynamic evaluation of almond shells pyrolytic behavior using Coats–Redfern and pyrolysis product distribution model

ABSTRACT Rigid environmental regulations and the energy crisis are pursuing researchers to investigate eco-friendly and more energy-generating alternatives to conventional resources. Biomass has the required potential and is drawing keen attention, especially in the field of energy. This work includes the thermal decomposition of almond shells under pyrolysis (N2) conditions in a thermogravimetric analyzer (TGA) and estimated pyrolysis product gas composition and thermo-kinetic parameters. Pyrolysis experiments were conducted at heating rates of 10°C/min, 20°C/min, and 30°C/min. Using 11 reaction models, the Coats–Redfern method was applied to determine kinetic and thermodynamic parameters. The pyrolysis product gas composition was estimated using correlations based on elemental composition and pyrolysis temperature. Thermal decomposition mainly occurred in the temperature range 150–550°C with a peak temperature of 292°C, 310°C, and 321°C for the three heating rates, i.e. 10°C/min, 20°C/min, and 30°C/min, respectively, and 99.40% total weight loss. High regression coefficients (R2) in the range of 0.90–0.99 were obtained for the Coats–Redfern models. High mean relative reactivity (0.04%min−1°C−1) and low activation energies showed a high tendency to degrade thermally. The overall activation energy Eα range for almond shell was 2–84 kJ/mol at all heating rates. The pyrolysis gas composition showed good agreement with the experimental results of similar biomass.

Composition of the Gas-Air Mixture in the Containment and Suppression of Forest Fires with Promising Extinguishing Agents

This paper presents experimental research findings on the gas composition of pyrolysis and combustion products of typical forest fuels (leaves, needles, twigs, a mixture of these, and timber). These experiments were performed for the combustion and application of a fire extinguishing agent to a pyrolyzing material. Water, a bischofite solution, a bentonite slurry, and a foaming agent solution were utilized. Two gas analysis systems were used, as follows: an industrial one based on CO2, CO, H2, CH4, and O2 sensors and a scientific one (a gas analyzer with H2, CH4, H2S, SO2, CO, and CO2 sensors). Fires were extinguished by using two common techniques, as follows: continuous liquid supply and cycling spraying. The comparative efficiency of applying a group of fire extinguishing agents to forest fires was estimated, taking account of liquid consumption, suppression time, and environmental pollution. A method was proposed for calculating the relative efficiency factors of fire extinguishing agents when containing and suppressing forest fires, allowing for the consumed time, resources, and anthropogenic emissions.

Hydrogen production and pollutants emission characteristics by co-gasified of paper-mill sludge and automobile shredder residues in a commercial scale fluidized bed gasifier

This research investigated the hydrogen production and energy conversion from automobile shredder residues (ASRs) and paper mill sludge (PMS) co-gasified in a full-scale fluidized bed gasification plant. The results obtained from full-scale tests provided important information on the feasible assessment of ASRs-to-energy and the selection of alternative technologies for ASRs. Based on the analysis results of produced gas composition, H2, CO, and CH4 composition produced from paper-mill sludge gasified were 4.17%–6.01%, 3.08%–4.32%, 1.71%–2.4%, respectively. Another C2 gas composition ranged from 2.9% to 3.59%. The heating value of produced gas ranged between 1.64 MJ/Nm3 and 2.18 MJ/Nm3. In the case of 10% ASR addition, the heating value of produced gas was slightly increased to 1.84 MJ/Nm3-2.34 MJ/Nm3. The dioxin emission concentration of flue gas was approximately 0.064 ng I-TEQ/Nm3. It can comply with Taiwan regulation thresholds. The dioxin leaching concentrations of residues derived from gasification were also in compliance with regulation limits by the TCLP test. Meanwhile, in the case of 10% ASRs addition, the dioxin equivalence concentration of gasified residue was nearly 0.002 ng I-TEQ/Nm3. It was far below the current regulation standard limit. In summary, the results of this research have proved the performance of ASRs-to-energy by co-gasified with paper mill sludge using a full-scale gasification plant. The results obtained from this research also provided the information for selecting ASRs alternative technologies and operating full-scale gasifiers in the future.

Application of MgO-Titanomagnetite mixture in high-temperature catalytic pyrolysis of radiata pine

This study aimed to investigate the effect of MgO and titanomagnetite mixture on the high-temperature pyrolysis of radiata pine wood in a fluidised bed reactor at 850 °C. The catalytic performance of the MgO-titanomagnetite (MgO-TM) mixture was experimentally evaluated based on product distribution, gas composition, gas properties, and tar composition. The results revealed that addition of MgO-titanomagnetite resulted in a decrease in gas yield (67.2 wt.%) compared to addition of titanomagnetite (TM) alone (72.9 wt.%), but an improvement was found compared to addition of MgO alone (63.9 wt.%). The hydrogen concentration in the gas product was significantly enhanced (23.2 vol.%) compared to titanomagnetite alone (12.8 vol.%) or to non-catalytic (NC) pyrolysis (14.1 vol.%) but was similar to that with addition of MgO alone (22.6 vol.%). However, the addition of MgO and titanomagnetite mixture resulted in a reduction in CO concentration to 2.7 vol.% in the gas product whereas increased the CO2 and light olefins formation. It was also found that the addition of the MgO and titanomagnetite mixture significantly increased the total concentration of ethylene and propylene (18.3 vol.%) compared to addition of titanomagnetite (5.8 vol.%), MgO (9.0 vol.%), or non-catalytic pyrolysis (12.0 vol.%). The lower heating value of the gas product and the H2 to CO ratio (17.5 MJ/Nm3 and 8.7) were also improved with addition of the MgO-titanomagnetite mixture. These findings demonstrate that application of physically mixed MgO and titanomagnetite as catalyst is a promising method for converting biomass into a H2-rich gas product via high-temperature pyrolysis. This study offers a useful reference for the development of novel catalytic systems for biomass conversion.Graphical

Investigations on biomass gasification of compact-fast dual fluidized bed calcium looping

In this study, a 10 kWth hot rig of dual fluidized bed is developed to investigate the performance of the calcium looping process for biomass hydrogen-rich gasification and carbon dioxide capture. The system consists of a compact fluidized bed and a fast fluidized bed riser. The compact fluidized bed, which is comprised of a lower bubbling fluidized bed and an upper riser, is used as the gasifier, and the fast fluidized bed riser is used as the regenerator. The solid from the regenerator goes upward from the bottom of the upper riser gasifier, and then downward to the lower bubble fluidized bed gasifier, bringing heat from the generator to the gasifier, and is finally circulated to the regenerator form the bottom of the bubble fluidized bed, taking carbon dioxide from the gasifier to the regenerator. Dolomite and quartz sand are used as bed materials. The effects of variables such as temperature, bed material, and solid circulating flux on product gas compositions, yield, calorific value, tar content, and cold gas efficiency were investigated. The dolomite bed material has a more obvious improvement in hydrogen production as compared with quartz sand as bed material. The maximum H2 production is 0.46 Nm3/kgFuel, the purity reaches 70.88%, the cold gas efficiency is 45.93%, and the low calorific value is 13.26 MJ/Nm3. The high temperature of the upper riser favors tar conversion. When the riser temperature was 800 °C, the tar content decreased by 4.46 g/Nm3, and the total gas production increased by 0.03 Nm3/kgFuel. In addition, the increase of solid circulating flux can improve the concentration and the yield of hydrogen, and decrease the content of tar.

Beyond purified dietary fibre supplements: Compositional variation between cell wall fibre from different plants influences human faecal microbiota activity and growth in vitro.

Dietary fibre is a major energy source for the human gut microbiota, but it is unclear to what extent the fibre source and complexity affect microbial growth and metabolite production. Cell wall material and pectin were extracted from five different dicotyledon plant sources, apples, beet leaves, beetroots, carrots and kale, and compositional analysis revealed differences in the monosaccharide composition. Human faecal batch incubations were conducted with 14 different substrates, including the plant extracts, wheat bran and commercially available carbohydrates. Microbial activity was determined for up to 72 h by measuring gas and fermentation acid production, total bacteria (by qPCR) and microbial community composition by 16S rRNA amplicon sequencing. The more complex substrates gave rise to more microbiota variation compared with the pectins. The comparison of different plant organs showed that the leaves (beet leaf and kale) and roots (carrot and beetroot) did not give rise to similar bacterial communities. Rather, the compositional features of the plants, such as high arabinan levels in beet and high galactan levels in carrot, appear to be major predictors of bacterial enrichment on the substrates. Thus, in-depth knowledge on dietary fibre composition should aid the design of diets focused on optimizing the microbiota.

Producer Gas Composition Prediction using Artificial Neural Network Algorithm

Nowadays, methods to increase efficiency in producer gas have become major issues in biomass gasification research. Producer gas is a renewable energy source that does not take as much time to obtain as fossil fuels. It is typically a mixture of combustible gases like carbon monoxide, hydrogen and methane, and non-combustible gases like carbon dioxide and nitrogen. A high percentage volume of combustible composition in the producer gas output will have a high calorific value or heat of combustion. These combustible gases are determined by the design of the gasifier. In today's era of Industrial Revolution 4.0 and Society 5.0, the use of simulation is highly prioritised in all aspects of engineering, especially in gasification applications. Simulation is a useful tool for learning about the governing principles and optimal operating points of the gasification process. Artificial intelligence (AI), is a major focus of Industry Revolution 4.0. In this project, the producer gas composition prediction is studied by computer simulation. The goals are to predict the output producer gas using an algorithm and to compare the trained prediction result with actual experiment data for rice husk gasification. This simulation was created with MATLAB software's artificial neural network (ANN). Three parameters (the height of the gasifier, the diameter of the gasifier, and the weight of the rice husk) are set as input data, and six types of the composition of producer gas (carbon dioxide, carbon monoxide, methane, oxygen, hydrogen, and nitrogen) are set as output data. The algorithm is trained, tested, and verified with the experiment data. It is then used to predict the output gas composition from the parameters of a gasification experiment that has been used before in UiTM’s laboratory. The simulation results of producer gas composition between prediction and actual values revealed a relative error of 1.159 %, 0.370 %, and 0.330 %. These results were less than 9% and were found to give a very good fit to the neural network algorithm.

Transformation of Heavy Oil Components in the Process of Initiated Cracking

In this work, the effect of butyl bromide on the thermal transformations of heavy oil from the Karmalskoye field (Republic of Tatarstan) in the presence of an initiating additive, n-butyl bromide, was studied. It was shown that the addition of butyl bromide increased the yield of gasoline and diesel fractions due to the destruction of high-molecular-weight components. It was established that almost all bromine from butyl bromide entered the compaction products upon the cracking of heavy oil, and butyl radicals entered the composition of gaseous products. It was noted that the direction of thermal transformations of hydrocarbons changed in the presence of butyl bromide. As compared to the initial oil, the amount of low-molecular-weight alkanes and isoprenoids increased significantly, the concentration of cyclohexanes and cyclopentanes decreased, and tri-, tetra- and pentacyclic saturated hydrocarbons were completely destroyed.

Biomass gasification to syngas in thermal water vapor arc discharge plasma

This study investigated biomass (wood pellets) gasification to syngas using direct current (DC) thermal arc plasma at atmospheric pressure. Water vapor was used as a main gasifying agent and a plasma-forming gas. The biomass gasification system was quantified in terms of the producer gas composition, the tar content, the H2/CO ratio, the carbon conversion efficiency, the energy conversion efficiency and the specific energy requirements. It was found that the gasification performance efficiency was highest at the water vapor-to-biomass ratio of 0.97. The producer gas was mostly composed of H2 (43.86 vol.%) and CO (30.93 vol.%), giving the H2/CO ratio of 1.42 and the LHV of 10.23 MJ/Nm3. However, high content of tars of 13.81 g/Nm3 was obtained in the syngas. The yield of H2 and CO was 48.31% and 58.13%, respectively, with the highest producer gas yield of 2.42 Nm3/kg biomass. The carbon conversion efficiency and the energy conversion efficiency were 100% and 48.83%, respectively, and the production of 1 kg of syngas required 1.78 kWh of electric energy input. Finally, the obtained results were compared with different plasma methods, including plasma-assisted application coupled with conventional gasification.

The influence of Pd4Cr6@(NH2)M-MOF(Cr) catalyst on components of formic acid dehydrogenation gaseous products

ABSTRACT In the dehydrogenation of formic acid, catalyst has a great influence on the composition and formation rate of gaseous products. However, the hydrogen used in fuel cells has strict requirements on the content of carbon monoxide impurities. Therefore, it is very important to study the relationship between catalyst components and their synergistic effects and the composition of gaseous products. The role of Pd-Cr bimetallic nanoparticles supported on amino modified Cr-based metal-organic framework catalyst (Pd4Cr6@(NH2)M-MOF(Cr)) in the formic acid dehydrogenation was explored through comparative experiments and catalyst characterization. Results show that both Cr-based metal-organic framework (MOF(Cr)) and amino-modified Cr-based metal-organic framework ((NH2)M-MOF(Cr)) have no effect on promoting the generation of gaseous products. The presence of Cr and NH2 groups in Pd4Cr6@(NH2)M-MOF(Cr) greatly improves the formation rate of H2 and CO2 products, the gas production rate of Pd4Cr6@(NH2)M-MOF(Cr) is 2.89 times that of Pd4@(NH2)M-MOF(Cr), and the gas production rate of Pd4Cr6@(NH2)M-MOF(Cr) is 6.26 times of Pd4Cr6@MOF(Cr). However, the formation rate of H2 increases more in the presence of Cr. Synergy of Pd-Cr and Pd-NH2 in the Pd4Cr6@(NH2)M-MOF(Cr) catalyst promotes CO formation.

Stationary expansion of gas mixture from a spherical source into vacuum

Sublimation under solar illumination of diverse ices composing the cometary nucleus forms multispecies gas coma. Depending on the heliocentric distance, the gas production of the nucleus varies in a broad range that results in circumnucleus flow regimes ranging from free-molecular to fluid. Therefore it is important to consider kinetic effects occurring in the gas and their influence on the flow and boundary conditions.We consider stationary flows of pure gases (H2O, CO2, CO) and their mixtures from a spherical surface. It is assumed that gas production of the surface is a consequence of sublimation within the surface layer. The detailed study of the structure and parameters of the gas outflow is based on the kinetic approach. The study considers flow conditions from fluid to free molecular.The results are numerically computed quantities which make the link between production rate, gas composition and surface temperature and: (1) velocities and abundances of gas species beyond the acceleration region; (2) mass, momentum and energy fluxes from the gas environment towards the surface; (3) parameters of the gas flow at the sonic surface circumscribing the source. Also, we define regions and conditions where the fluid approximation of the flow can be correctly applied. These data are necessary for definitions of parameters in: (1) simplified “Haser-type” models; and (2) advanced models of cometary activity which take into consideration the influence of gas environment on nucleus surface; and (3) coma models based on the fluid description of the gas flow.

Pyrolysis kinetics of bio-based polyurethane: Evaluating the kinetic parameters, thermodynamic parameters, and complementary product gas analysis using TG/FTIR and TG/GC-MS

In this study, the pyrolysis behavior and reaction kinetics of bio-based polyurethane (BPU) was investigated in comparison to the individual components enzymatic lignin (EL) and polyurethane (PU). The produced gas composition during their pyrolysis were investigated using thermogravimetric (TG) analysis combined with FTIR and TG coupled with TG-GC/MS. TG analysis indicated that the decomposition of BPU was comparable with that of PU. However, the larger peak temperatures in DTA curves and residue mass for BPU than that for PU indicated that the incorporation of EL improved its thermal resistance. Most of the absorbance bands in FTIR for both samples were similar, except of the absorbance at 1500-1750 cm−1 for PU and 1000-1150 cm−1 for BPU. The dominant evolved products were N-containing compounds for PU and BPU, however, the phenols and furans were detected during BPU pyrolysis. Based on the Flynn-Wall-Ozawa model, the average activation energy was determined as 176.1 kJ mol−1 for BPU, which was larger than 159.5 kJ mol−1 for PU and smaller than that of 298.5 kJ mol−1 for EL. For PU and BPU, the experimental curves were comparable with F1.5 model at the conversion rate in the α range of 0.1–0.5 and F3 model beyond that range.

Valorization of Sugarcane Bagasse for Hydrogen-Rich Gas Production using Thermodynamic Modeling Approach

Hydrothermal gasification also known as supercritical water gasification (SWG) has been considered a promising approach for converting wet biomass such as sugarcane bagasse into high-quality syngas. This study presents the thermodynamic modeling of the hydrothermal gasification of sugarcane bagasse using Aspen Plus. The effects of process parameters on the composition and yield of product gases were also investigated. It was found that the effect of temperature and biomass concentration were significant in the production of hydrogen-rich gas, while less impact was observed with pressure. The hydrogen gas (H2) produced with the highest mole fraction (56.70 mol%) and yield (103.26 kmol/kg) was obtained at 750°C and low biomass concentration of 10 wt%, while the lowest yield (1.52 kmol/kg) and mole fraction (2.45 mol%) of H2 were obtained at 450°C and high biomass concentration of 50 wt%. Findings from this study also showed that the highest net calorific value (17.55MJ/kg) was reached at 450˚C and 50 wt% of biomass concentration. This study would help to consolidate research on hydrothermal gasification of sugarcane bagasse and optimization of experimental processes and also serve as an important benchmark in the utilization of biomass as a clean energy source for future projects.

Effect of Biomass Particle Size on the Torrefaction Characteristics in a Fixed-Bed Reactor

The aim of this study is to investigate the influence of biomass particle size on the torrefaction characteristics under different torrefaction temperatures and times. Paulownia wood with particle sizes ranging from 12 to <0.3 mm was selected. It was torrefied at 260 and 290 °C in a fixed-bed reactor for 30–90 min. The results showed that biomass particle size did affect the product’s evolution during biomass torrefaction. With the decrease in particle size from 12 to <0.3 mm, the yield of the solid product decreased by 5.41 and 3.54 wt.%, the yield of the liquid product increased by 5.87 and 3.25 wt.%, and the yield of the gas product changed insignificantly, at 260 and 290 °C, respectively. Comparatively, torrefaction temperature had a more significant effect on the composition of gas products than particle size and torrefaction time. At lower temperatures, decarboxylation reactions dominated in the torrefaction process with more CO2 produced. However, at higher temperatures, decarbonylation reactions were significantly strengthened with more CO generated. The contents of CO2 and CO could account for more than 98 vol% of the product gas. The influence of particle size on the chemical composition of the solid product was much smaller than that of torrefaction temperature and time, but the energy yield of the solid product decreased with the decrease in particle size. The increase in torrefaction temperature and time could significantly increase the C content in the solid product while reducing its O content. It is recommended to use a relatively higher temperature (e.g., 290 °C) for the torrefaction of large particle biomass, as it could significantly reduce the impact of particle size on the torrefaction process and reduce the torrefaction time.

Impact of Plastic Blends on the Gaseous Product Composition from the Co-Pyrolysis Process

The co-pyrolysis of various biomasses mixed with two types of plastic waste was investigated in this study. Mixture M1 consisted of 30% m/m styrene–butadiene rubber (SBR), 40% m/m polyethylene terephthalate (PET), and 30% m/m polypropylene (PP). M2 consisted of 40% m/m PET, 30% m/m PP, and 30% m/m acrylonitrile–butadiene–styrene copolymer (ABS). The SBR, ABS, and PP used in this study were from the automotive industry, while the PET originated from scrap bottles. Co-pyrolysis was performed using wood biomass, agricultural biomass, and furniture trash. Thermal treatment was performed on samples from room temperature to 400 or 600 °C at a heating rate of 10 °C/min under N2 at a flow rate of 3 dm3/min. Based on the findings of the experiments, an acceptable temperature was found for the fixed-bed pyrolysis of biomass–plastic mixtures with varying ratios, and the raw materials were pyrolyzed under the same conditions. The composition of the derived gaseous fraction was investigated. The co-pyrolysis studies and variance analysis revealed that combining biomass with plastic materials had a good influence on the gaseous fraction, particularly in the presence of 6.6–7.5% v/v hydrogen and a lower heating value of 15.11 MJ/m3. This type of gaseous product has great potential for use as a replacement for coke oven gas in metallurgy and other applications.

Comparative study on the gasification performance of two energy crops by steam or carbon dioxide

The gasification of two energy crops (Cynara cardunculus L. and Helianthus annuus L.), under steam or carbon dioxide atmosphere, in a fixed bed system was compared. The efficiency of the process was determined in terms of thermal behavior, reactivity, conversion, energy recovery and product gas composition, which was quantitatively analyzed by a mass spectrometer unit. When the steam/biochar ratio increased from 1 to 3, conversion was enhanced and the concentration of H2 in the product gas was raised up to 56 %. The yield of syngas was higher for cardoon fuel and that of CO2 lower, as compared to helianthus fuel. Upon carbon dioxide gasification, helianthus biochar presented a higher reactivity and conversion (80.7 %) than cardoon biochar (64.9 %). Under a steam atmosphere the higher heating value of generated gas was lower, however energy recovery from the two crops was significantly enhanced in relation to carbon dioxide gasification.

Feedstock flexible numerical analysis of sewage sludge gasification

Sewage sludge properties vary with the origin and treatment method of the wastewater. When converting the sewage sludge thermally for material and energy recovery, these properties affect the composition of the products and the efficiency of the process. Rotary kiln gasifiers can handle these variations in the raw materials. For further development, process integration, optimization of the process, upscaling, and industrial application, it is helpful to understand and describe the impact of the sewage sludge properties on operating parameters and product quality. This work analyses the impact of sewage sludge properties numerically using detailed chemistry and the surrogate approach. Sewage sludge is described using woody biomass components, sugars, lipids, proteins, inorganic species, moisture, and ash. The stochastic reactor model (SRM) is used to model the gasification process. In contrast to ideal reactors, stochastic reactors allow for resolving inhomogeneity. Hence, the predicted gas composition results from local temperature and available oxygen. For the analysis, temperature, airflow rate, and fuel properties, i.e., the amount and composition of volatiles, including fuel-bonded nitrogen and sulfur, and the moisture level are varied. Their results are analysed regarding the produced gas composition, emission precursor formation, and cold gas efficiency of the process. The highest efficiencies are found for temperatures of 1223 K and rich conditions. High concentrations of methane and hydrogen accompany this maximum. However, the producer gas’s highest heating value is found at low temperatures thanks to the presence of small hydrocarbons. Furthermore, a high volatile amount and a dry feedstock favour methane and carbon monoxide formation. The hydrogen concentration is found to be sensitive to the moisture content and is the highest at 30%. The cold gas efficiency is predicted to depend strongly on the feedstock and varies for the same operating conditions up to 60%. With increasing fuel-bonded nitrogen and sulfur content, the concentrations of NO and SO2 formation and their precursors increase, respectively. The released ammonia leads to significantly reducing emitted NO through the ThermalDeNOx mechanism. Overall, the generated maps provide a detailed insight in species formation and allows for the prediction of process parameters sensitive to the sewage sludge properties.

Combined combustion of pulverized coal and liquid fuel in a low power vortex burner

In this work we study the process of co-combustion of pulverized coal fuel (coal grinded up to 100 microns) and liquid (diesel) fuel in a new low power burner, where coal-air mixture is fed tangentially together with secondary air, and liquid fuel is atomized by a high velocity steam jet. Temperature profiles and composition of intermediate combustion products along the vertical axis of the burner have been studied. The heat release (power) and the gas composition of final combustion products have been measured. This allowed us to demonstrate the principal possibility of combined combustion of coal dust and diesel fuel in a compact laboratory burner.