Experimental analysis of air-steam gasification of biomass with coal-bottom ash

Biomass gasification is an attractive option for producing high-quality syngas (H₂+CO) due to its environmental advantages and economic benefits. However, due to some technical problems such as tar formation, biomass gasification has not yet been able to achieve its purpose. The purpose of this work was to study the catalytic activity of coal-bottom ash for fuel gas production and tar elimination. Effect of gasification parameters including reaction temperature (700–900 °C), equivalence ratio, EQR (0.15–0.3) and steam-to-biomass ratio, SBR (0.34–1.02) and catalyst loading (5.0–13 wt %) on gas distribution, lower heating value (LHV) of gas steam, tar content, gas yield and H₂/CO ratio was studied. The tar content remarkably decreased from 3.81 g/Nm³ to 0.97 g/Nm³ by increasing char-bottom ash from 5.0 wt% to 13.0 wt%. H₂/CO significantly increased from 1.12 to 1.54 as the char-bottom ash content in the fuel increased from 5.0 wt% to 13.0 wt%.     

Experimental research for biomass steam gasification in a fluidized bed

A fluidized bed gasification system was built to investigate the biomass steam gasification performance in different conditions. Medium heating value syngas with 34% H₂ content and no more than 20 g/Nm³ tar content could be obtained under 800°C with a S/B (steam vs. biomass ratio) of 0.9 by using olivine as bed material. The results indicated that syngas quality (including H₂ content, gasification efficiency, tar reduction, etc.) is in a positive correlation with temperature and S/B, but has a negative correlation with fluidization number (FN). Compared with quartz sand and dolomite, olivine is more suitable for fluidized bed because of its catalytic ability and good abrasion performance for fluidized bed gasifier. As a result, a set of optimum parameters is recommended with S/B of 0.9~1.0, FN of 1.4, and temperature of 800°C in this study.

Tar is a by-product from the gasification process, which will cause the pipeline congestion, reduce the gasification efficiency, and deteriorate the working condition. According to this experiment, the temperature and S/B both have a negative effect on tar content, while tar content increased with increase in the FN. Dolomite and olivine both have an inhibition function on tar, and the olivine is considered the best choice of bed material because of its good anti-wear properties.     

Co–gasification of coal/biomass blends in 50 kWe circulating fluidized bed gasifier

This paper reports gasification of coal/biomass blends in a pilot scale (50 kWe) air-blown circulating fluidized bed gasifier. Yardsticks for gasification performance are net yield, LHV and composition and tar content of producer gas, cold gas efficiency (CGE) and carbon conversion efficiency (CCE). Net LHV decreased with increasing equivalence ratio (ER) whereas CCE and CGE increased. Max gas yield (1.91 Nm³/kg) and least tar yield (5.61 g/kg of dry fuel) was obtained for coal biomass composition of 60:40 wt% at 800 °C. Catalytic effect of alkali and alkaline earth metals in biomass enhanced char and tar conversion for coal/biomass blend of 60:40 wt% at ER = 0.29, with CGE and CCE of 44% and 84%, respectively. Gasification of 60:40 wt% coal/biomass blend with dolomite (10 wt%, in-bed) gave higher gas yield (2.11 Nm³/kg) and H₂ content (12.63 vol%) of producer gas with reduced tar content (4.3 g/kg dry fuel).     

Effect of design and operating parameters on the gasification process of biomass in a downdraft fixed bed: An experimental study

The main objective of this paper is to study the effect of design and operating parameters, mainly reactor geometry, equivalence ratio and biomass feeding rate, on the performance of the gasification process of biomass in a three air stage continuous fixed bed downdraft reactor. The gasification of corn straw was carried out in the gasifier under atmospheric pressure, using air as gasifying agent. The results demonstrated that due to the three stage of air supply, a high and uniform temperature was achieved in the oxidation and reduction zones for better tar cracking. The designing of both the air supply system and rotating grate avoided bridging and channeling. The gas composition and tar yield were affected by the parameters including equivalence ratio (ER) and biomass feeding rate. When biomass feeding rate was 7.5 kg/h and ER was 0.25–0.27, the product gas of the gasifier attained a good condition with lower heating value (LHV) about 5400 kJ/m³ and cold gas efficiency about 65%. An increase in equivalence ratio led to higher temperature which in turn resulted in lower tar yield which was only 0.52 g/Nm³ at ER = 0.32. Increasing biomass feeding rate led to higher biomass consumption rate and process temperature. However, excessively high feeding rate was unbeneficial for biomass gasification cracking and reforming reactions, which led to a decrease in H₂ and CO concentrations and an increase in tar yield. When ER was 0.27, with an increase of biomass feeding rate from 5.8 kg/h to 9.3 kg/h, the lower heating value decreased from 5455.5 kJ/Nm³ to 5253.2 kJ/Nm³ and tar yield increased from 0.82 g/Nm³ to 2.78 g/Nm³.     

Novel hydrogen‐rich gas production by steam gasification of biomass in a research‐scale rotary tubular helical coil gasifier

The concept of biomass steam gasification offers platform for production (i) of hydrogen, (ii) hydrocarbons and (iii) value added chemicals. Majority of these developments are either in nascent or in pilot/demonstration stage. In this context, there exists potential for hydrogen production via biomass steam gasification. Gaseous products of biomass steam gasification consist of large percentage of CO, CH₄ and other hydrocarbons, which can be converted to hydrogen through water‐gas‐shift reaction, steam reforming and cracking respectively. Although there are many previous research works showing the potential of production of hydrogen from biomass in a two stage process, challenges remain in extended biomass and char gasification so as to reduce the amount of carbon in the residual char as well as improve conversion of heavy hydrocarbon condensates to hydrogen rich gas. In the current work, the characteristics of biomass steam gasification in an in‐house designed rotary tubular helical coil reactor at temperatures less than 850 °C, in the presence of superheated steam, were presented. The objectives were to obtain high carbon conversion in the primary biomass steam gasification step (upstream) and high product gas yield and hydrogen yield in the secondary fixed bed catalytic step (downstream). The influence of temperature, steam‐to‐biomass ratio and residence time on product gas yield in the rotary tubular helical coil gasifier was studied in detail using one of the abundantly available biomass sources in India‐rice husk. Further, enhancement of product gas yield and hydrogen yield in a fixed bed catalytic converter was studied and optimized. In the integrated pathway, a maximum gas yield of 1.92 Nm³/kg moisture‐free biomass was obtained at a carbon conversion efficiency of 92%. The maximum hydrogen purity achieved under steady state conditions was 53% by volume with a hydrogen yield of 91.5 g/kg of moisture‐free biomass. This study substantiates overall feasibility of production of high value hydrogen from locally available biomass by superheated steam gasification followed by catalytic conversion. Copyright © 2016 John Wiley & Sons, Ltd.     

Integrated catalytic adsorption (ICA) steam gasification system for enhanced hydrogen production using palm kernel shell

This paper investigates the integrated catalytic adsorption (ICA) steam gasification of palm kernel shell for hydrogen rich gas production using pilot scale fluidized bed gasifier under atmospheric condition. The effect of temperature (600–750 °C) and steam to biomass ratio (1.5–2.5 wt/wt) on hydrogen (H₂) yield, product gas composition, gas yield, char yield, gasification and carbon conversion efficiency, and lower heating values are studied. The results show that H₂ hydrogen composition of 82.11 vol% is achieved at temperature of 675 °C, and negligible carbon dioxide (CO₂) composition is observed at 600 °C and 675 °C at a constant steam to biomass ratio of 2.0 wt/wt. In addition, maximum H₂ yield of 150 g/kg biomass is observed at 750 °C and at steam to biomass ratio of 2.0 wt/wt. A good heating value of product gas which is 14.37 MJ/Nm³ is obtained at 600 °C and steam to biomass ratio of 2.0 wt/wt. Temperature and steam to biomass ratio both enhanced H₂ yield but temperature is the most influential factor. Utilization of adsorbent and catalyst produced higher H₂ composition, yield and gas heating values as demonstrated by biomass catalytic steam gasification and steam gasification with in situ CO₂ adsorbent.     

Hydrogen-rich gas production from biomass steam gasification in an updraft fixed-bed gasifier combined with a porous ceramic reformer

This paper investigates the hydrogen-rich gas produced from biomass employing an updraft gasifier with a continuous biomass feeder. A porous ceramic reformer was combined with the gasifier for producer gas reforming. The effects of gasifier temperature, equivalence ratio (ER), steam to biomass ratio (S/B), and porous ceramic reforming on the gas characteristic parameters (composition, density, yield, low heating value, and residence time, etc.) were investigated. The results show that hydrogen-rich syngas with a high calorific value was produced, in the range of 8.10–13.40 MJ/Nm³, and the hydrogen yield was in the range of 45.05–135.40 g H₂/kg biomass. A higher temperature favors the hydrogen production. With the increasing gasifier temperature varying from 800 to 950 °C, the hydrogen yield increased from 74.84 to 135.4 g H₂/kg biomass. The low heating values first increased and then decreased with the increased ER from 0 to 0.3. A steam/biomass ratio of 2.05 was found as the optimum in the all steam gasification runs. The effect of porous ceramic reforming showed the water-soluble tar produced in the porous ceramic reforming, the conversion ratio of total organic carbon (TOC) contents is between 22.61% and 50.23%, and the hydrogen concentration obviously higher than that without porous ceramic reforming.     

Hydrogen production from oil sludge gasification/biomass mixtures and potential use in hydrotreatment processes

Gasification of oil sludge (OS) from crude oil refinery and biomass was investigated to evaluate hydrogen production and its potential use in diesel oil hydrodesulphurization process. Gasification process was studied by Aspen Hysys^® tools, considering different kinetic model for main OS compounds. Air and superheated steam mixtures as gasifying agents were simulated. Gasification parameters like: temperature, syngas chemical composition and gas yield were evaluated. Results showed OS thermal conversion needs a working temperature above 1300 °C to ensure a high conversion (>90%) of OS compounds. Thermal energy requirement for gasification was estimated between 0.80 and 1.25 kWh/kg OS, considering equivalence air (ER) and steam/oil sludge (SOS) ratio between 0.25-0.37 and 0.2–1.5 kg steam/kg OS, respectively. The gas yield was 2.28 Nm³/kg OS, with a H₂ content close to 25 mol%, for a H₂ potential production about 1.84 Nm³ H₂/kg OS; nevertheless, when OS and biomass mixtures are used, hydrogen production increases to 3.51 Nm³ H₂/kg OS, meaning 37% of H₂ (from natural gas) required for diesel oil hydrodesulphurization could be replaced, becoming an added value technological alternative for OS waste conversion as a source of H₂, inducing a considerable reduction of greenhouse gases and non-renewables resources.     

Biomass gasification in a 100 kWth steam-oxygen blown circulating fluidized bed gasifier: Effects of operational conditions on product gas distribution and tar formation

Biomass gasification is one of the most promising technologies for converting biomass, a renewable source, into an easily transportable and usable fuel. Two woody biomass fuels Agrol and willow, and one agriculture residue Dry Distiller’s Grains with Solubles (DDGS), have been tested using an atmospheric pressure 100 kWth steam-oxygen blown circulating fluidized bed gasifier (CFB). The effects of operational conditions (e.g. steam to biomass ratio (SBR), oxygen to biomass stoichiometric ratio (ER) and gasification temperature) and bed materials on the composition distribution of the product gas and tar formation from these fuels were investigated. Experimental results show that there is a significant variation in the composition of the product gas produced. Among all the experiments, the averaged concentration of H₂ obtained from Agrol, willow and DDGS over the temperature range from 800 to 820 °C was around 24 vol.%, 28 vol.% and 20 vol.% on a N₂ free basis, respectively. A fairly high amount of H₂S (∼2300 ppmv), COS (∼200 ppmv) and trace amounts of methyl mercaptan (<3 ppmv) on a N₂ free basis were obtained from DDGS. Due to a relatively high content of K and Cl in DDGS fuel, an alkali-getter (e.g. kaolin) was added to avoid agglomeration during gasification. Higher temperatures and SBR values were favorable for increasing the mole ratio of H₂ to CO and the tar decomposition but less advantageous for the formation of CH₄. Meanwhile, higher temperatures and SBR values also led to higher gas yields, whereas a higher SBR caused a lower carbon conversion efficiency (CCE%), cold gas efficiency (CGE%) and heating values of the product gas due to a high steam content in the product gas. From solid phase adsorption (SPA) results, the total tar content obtained from Agrol was the highest at around 12.4 g/Nm³, followed by that from DDGS and willow gasification. The lowest tar content produced from Agrol, willow and DDGS using Austrian olivine (Bed 1) as bed materials was 5.7, 4.4 and 7.3 g/Nm³, values which were obtained at a temperature of 730, 820 and 730 °C, SBR of 1.52, 1.14 and 1.10, and ER of 0.36, 0.39 and 0.37, respectively.     

Experimental study on sawdust gasification in a spout–fluid bed reactor

This paper summarizes the experimental results of sawdust gasification in a spout–fluid bed reactor. Three scenarios were investigated in this study. In the base case scenario, a total of 15 experiments consisting of three different flow rates (55, 65 and 75 m³ h^{? 1}) of primary air of each of having five equivalence ratios (ER) (0.35, 0.3, 0.25, 0.2 and 0.15) were conducted. The influence of secondary air in the freeboard and the effect of the recirculation of carryover captured by the cyclone to the reactor's freeboard at an ER of 0.25 were investigated in two other scenarios. Higher heating values of 3.02 and 5.15 MJ Nm^{? 3} were obtained with the ER values of 0.35 and 0.15, respectively, in the base case. However, opposite trend was observed for the tar content in the producer gas. At ER of 0.35, a value of 2.35 g Nm^{? 3} was found compared with 8.4 g Nm^{? 3} at ER of 0.15. The tar content in the producer gas was reduced from 5.63 to 1.53 g Nm^{? 3} when secondary air was supplied in the freeboard due to an increase in temperature. The gasification efficiency was increased from 24.96% at the base case to 36.22% with the recirculation of carryover. Higher heating value of producer gas was found to be 4.2–4.4 MJ Nm^{? 3} in this case. The second law analysis of this process estimated the average exergy efficiency as 35.92% at ER of 0.35 and it increased with increasing ER. The recirculation of carryover not only increased the carbon conversion efficiency but also the exergy efficiency. Copyright © 2010 John Wiley & Sons, Ltd.     

Biomass to hydrogen-rich syngas via tar removal from steam gasification with La1-XCeXFeO3/dolomite as a catalyst

Biomass gasification produces hydrogen, which is a clean and promising technology. One of the most important aspects of the biomass gasification process is choosing the right catalyst. In this study, 10% La_1-XCe_XFeO₃/Dolomite (X = 0,0.2,0.4,0.6,0.8) synthesized using the sol-gel method was used as a catalyst in biomass gasification for the production of hydrogen-rich syngas. Gasification tests were carried out in a fixed bed reactor. The effects of an elemental substitution in LaFeO₃, temperature on the product were examined. Ce-substitution boosted the activity of LaFeO₃/DOL according to the data. Among the prepared catalysts, La_0.8Ce_0.2FeO₃/DOL performed the best, yielding a greater H₂ production and tar with a higher naphthalene concentration. As the temperature rises, so does the H₂ yield, at 850 °C, the highest H₂ yield is 0.69Nm³/Kg. Furthermore, the aromatization of phenols in tar is more likely to occur at high temperatures.     

Influences of equivalence ratio,oxygen concentration and fluidization velocity on the characteristics of oxygen-enriched gasification products from biomass in a pilot-scale fluidized bed

The influences of equivalence ratio (ER), oxygen concentration (OC) and fluidization velocity (FV) on the gasification performance in a pilot-scale fluidized bed with capacity of 1 ton biomass (the mixture of agricultural residue) per day were investigated using oxygen-enriched air as gasification agent and high-alumina bauxite as bed material. The characteristics of syngas (lower heating value (LHV), gas yield (Y), carbon conversion (CC) and cold gas efficiency (CGE)), bio-char (LHV and Proximate analysis) and tar (tar yield and LHV) were used to evaluate the gasification performance in this study. The results showed that 0.161 was the optimal ER due to the high quality of syngas produced and relatively lower tar generation with ER changing from 0.115 to 0.243 at OC ≈ 40% and FV ≈ 1.20.29.7% was the optimal OC due to the highest Y and CC and relatively low tar generation when OC varied from 21% to 44.7% at ER ≈ 1.40 and FV ≈ 1.15. Although higher FV could improve syngas quality, it also resulted in the higher tar yield and heavier wear, therefore, the optimal gasification performance was achieved at moderate FV (FV = 1.13). This study proved that oxygen-enriched gasification in a large-scale fluidized bed was an effective option to produce gaseous biofuels with high quality.     

The performance of nickel-loaded lignite residue for steam reforming of toluene as the model compound of biomass gasification tar

Tars should be removed from biomass gasification systems so as not to damage or clog downstream pipes or equipment. In this paper, lignite insoluble residue (LIR) after extraction of humic acids was used as the support to prepare a nickel-loaded LIR (Ni/LIR) catalyst. This novel catalyst Ni/LIR was tested in steam reforming of toluene as a model compound of biomass tar conducted in a laboratory-scale fixed bed reactor. When compared to the reactions without catalyst or with Ni/Al₂O_3, Ni/LIR was confirmed as an active catalyst for toluene conversion at a relatively low temperature of 900 K. The investigated reforming parameters during the experiments in this research were selected as reaction temperature at a range of 850–950 K, steam/carbon molar ratio at a range of 2–5 mol/mol, and a space velocity from 1696 to 3387 h^?1. It was concluded that, under optimum conditions, significant amount of syngas yields, acceptable Ni/LIR consumption and more than 95% of toluene conversion can be obtained from the biomass Ni/LIR catalytic gasification system.     

Hydrogen-rich gas from catalytic steam gasification of biomass in a fixed bed reactor: Influence of particle size on gasification performance

The catalytic steam gasification of biomass was carried out in a lab-scale fixed bed reactor in order to evaluate the effects of particle size at different bed temperatures on the gasification performance. The bed temperature was varied from 600 to 900 °C and the biomass was separated into five different size fractions (below 0.075 mm, 0.075–0.15 mm, 0.15–0.3 mm, 0.3–0.6 mm and 0.6–1.2 mm). The results show that with decreasing particle size, the dry gas yield, carbon conversion efficiency and H₂ yield increased, and the content of char and tar decreased. And the differences due to particle sizes in gasification performance practically disappear as the higher temperature bound is approached. Hydrogen and carbon monoxide contents in the produced gas increase with decreasing particle size at 900 °C, reaching to 51.2% and 22.4%, respectively.     

Performance evaluation of an innovative 100 kWth dual bubbling fluidized bed gasifier through two years of experimental tests: Results of the BLAZE project

In this work, the results of two years of experimental tests on an innovative dual bubbling fluidized bed gasifier are reported. These are related to the activities of the BLAZE project (Horizon 2020) for the integration of steam biomass gasification and solid oxide fuel cell. Several tests were carried out on the pilot-scale reactor at various operating conditions, and in this work the results are reported in terms of dry gas composition and yield, organic and inorganic contaminants (tar, particulate matter, H₂S). The compact design of the gasifier (a single reactor with two concentric chambers and in-situ hot gas cleaning and conditioning) reduces the heat losses and produces close to nitrogen-free syngas. Preliminary tests using a filter candle filled with conventional catalyst, installed in the freeboard of the gasifier, show that the tar content dropped to about 2 g/Nm³, and the H₂ concentration increased up to 41%_vol,dry.     

Desulfurization and tar reforming of biogenous syngas over Ni/olivine in a decoupled dual loop gasifier

For the production of bio-SNG (substitute natural gas) from syngas of biomass steam gasification, trace amounts of sulfur and tar compounds in raw syngas must be removed. In present work, biomass gasification and in-bed raw gas upgrading have been performed in a decoupled dual loop gasifier (DDLG), with aggregation-resistant nickel supported on calcined olivine (Ni/olivine) as the upgrading catalyst for simultaneous desulfurization and tar elimination of biogenous syngas. The effects of catalyst preparation, upgrading temperature and steam content of raw syngas on sulfur removal were investigated and the catalytic tar reforming at different temperatures was evaluated as well. It was found that 850 °C calcined Ni/olivine was efficient for both inorganic-sulfur (H₂S) and organic-sulfur (thiophene) removal at 600–680 °C and the excellent desulfurization performance was maintained with wide range H₂O content (27.0–40.7%). Meanwhile, tar was mostly eliminated and H₂ content increased much in the same temperature range. The favorable results indicate that biomass gasification in DDLG with Ni/olivine as the upgrading bed material could be a promising approach to produce qualified biogenous syngas for bio-SNG production and other syngas-derived applications in electric power, heat or fuels.     

Steam catalytic gasification of municipal solid waste for producing tar-free fuel gas

In the paper, a two-region municipal solid waste (MSW) steam catalytic gasification process was proposed. The gasifier was composed of two individual reactors: one is the gasification reactors and the other is the catalytic reactor. The MSW was initially gasified and the produced tar was gasified in the gasification reactor, and further, the tar not gasified entered the catalytic reactor together with the fuel gas and was catalytically decomposed to fuel gas. The influences of the catalysts, steam and temperature on the content of tar, dry gas yield and composition, and carbon conversion efficiency were studied. The results indicated that under the optimum operating conditions, the dry gas yield can be up to 1.97 Nm³/kg MSW and the tar in the product can be completely eliminated. The concentration of hydrogen, carbon monoxide and methane in the fuel gas produced was 50.8%, 9.32% and 13.3%, respectively.     

Hydrogen-rich gas production from pyrolysis of wet sludge in situ steam agent

A series of wet sludge samples with different moisture contents were pyrolyzed in situ steam in a bench-scale fixed bed reactor in order to examine the influence of moisture and temperature on product distribution and gas composition. The results demonstrated that inherent moisture in wet sludge had a great effect on the product yield. The pyrolysis of wet sludge (43.38% moisture content) at 800 °C exhibited maximum H₂ yield (7.76 mol kg^?1 dry basis wet sludge) and dry gas yield (0.61 Nm³ kg^?1) and H₂ content of 42.13 vol%. When the moisture exceeded 43.38%, H₂ yield and gas yield both tended to decline. It was also shown that the elevated temperature exhibited a significant influence on gas content increase and tar reduction; at the same time, H₂ yield and H₂ content were increased from 1.83 mol kg^?1 dry basis wet sludge and 16.67 vol% to 9.15 mol kg^?1 dry basis wet sludge and 45.67 vol%, respectively, as temperature increased from 600 °C to 850 °C. LHV of fuel gas varies from 15.49 MJ Nm^?3 to 11.65 MJ Nm^?3 because of decrease in CH₄ and C₂H₄ content as temperature increasing. In conclusion, hydrogen rich gas production by pyrolysis of wet sludge which avoided pre-drying process and utilized in situ steam agent from wet sludge is an economic method.     

Investigation of a multi-generation system using a hybrid steam biomass gasification for hydrogen, power and heat

In this paper, an integrated process of steam biomass gasification and a solid oxide fuel cell (SOFC) is investigated energetically to evaluate both electrical and energy efficiencies. This system is conceptualized as a combined system, based on steam biomass gasification and with a high temperature, pressurized SOFC. The SOFC system uses hydrogen obtained from steam sawdust gasification. Due to the utilization of the hydrogen content of steam in the reforming and shift reaction stages, the system efficiencies reach appreciable levels. This study essentially investigates the utilization of steam biomass gasification derived hydrogen that was produced from an earlier work in a system combines gasifier and SOFC to perform multi-duties (power and heat). A thermodynamic model is developed to explore a combination of steam biomass gasification, which produces 70–75 g of hydrogen/kg of biomass to fuel a planar SOFC, and generate both heat and power. Furthermore, processes are emerged in the system to increase the hydrogen yield by further processing the rest of gasification products: carbon monoxide, methane, char and tar. The conceptualized scheme combines SOFC operates at 1000 K and 1.2 bar and gasifier scheme based on steam biomass gasification which operates close to the atmospheric pressure, a temperature range of 1023–1423 K and a steam-biomass ratio of 0.8 kmol/kmol. A parametric study is also performed to evaluate the effect of various parameters such as hydrogen yield, air flow rate etc. on the system performance. The results show that SOFC with an efficiency of 50.3% operates in a good fit with the steam biomass gasification module with an efficiency, based on hydrogen yield, of 55.3%, and the overall system then works efficiently with an electric efficiency of ∼82%.     

Downdraft gasifier structure and process improvement for high quality and quantity producer gas production

The current study reveals several efficient amenities that can affect the gasification process to improve syngas quality and yield. A comprehensive study was carried out using a 24 kW downdraft gasifier to evaluate the effect of uniform air distribution in the oxidation zone, additional throat on the reactor temperature distribution and the overall gasification process. The effect of fuel moisture, equivalence ratio, gasifying agent type and pre-treatment of the gasifying agent on producer gas yield and composition were also evaluated. The biomass feeding rate was 30–40 kg/h, and the maximum gas flow rate was 90 m³/h. When corn cobs and waste wood (carpenter waste) with moisture content from 5 to 30% were used as feed stock, with 70 °C air as the gasifying/oxidizing agent, the energy value of the producer/syngas obtained was 6.31 and 6.66 MJ/m³, respectively. The heating value was improved to 6.72 and 8.43 MJ/m³ when using 150 °C air-steam mixture as the gasifying agent, with the optimum equivalence ratio of 0.30. The methane, hydrogen and carbon monoxide concentration (on volume basis) were 6.20, 19.32 and 21.00. The average amount of syngas produced from 1 kg of corn cobs and waste wood were 2.94 and 2.62 m³, while the average amount of tar produced was 2.2 and 1.8 g/Nm³ respectively. The investigation revealed that uniform air distribution in the oxidation zone, fuel moisture content, gasifying agent type and the pre-treatment of gasifying agent played a significant role in enhancing the quantity and quality of the producer gas.