Biomass Gasification For Production Research Articles

Hydrogen-rich gas production from biomass air and oxygen/steam gasification in a downdraft gasifier

Biomass gasification is an important method to obtain renewable hydrogen. However, this technology still stagnates in a laboratory scale because of its high-energy consumption. In order to get maximum hydrogen yield and decrease energy consumption, this study applies a self-heated downdraft gasifier as the reactor and uses char as the catalyst to study the characteristics of hydrogen production from biomass gasification. Air and oxygen/steam are utilized as the gasifying agents. The experimental results indicate that compared to biomass air gasification, biomass oxygen/steam gasification improves hydrogen yield depending on the volume of downdraft gasifier, and also nearly doubles the heating value of fuel gas. The maximum lower heating value of fuel gas reaches 11.11 MJ/N m 3 for biomass oxygen/steam gasification. Over the ranges of operating conditions examined, the maximum hydrogen yield reaches 45.16 g H 2/kg biomass. For biomass oxygen/steam gasification, the content of H 2 and CO reaches 63.27–72.56%, while the content of H 2 and CO gets to 52.19–63.31% for biomass air gasification. The ratio of H 2/CO for biomass oxygen/steam gasification reaches 0.70–0.90, which is lower than that of biomass air gasification, 1.06–1.27. The experimental and comparison results prove that biomass oxygen/steam gasification in a downdraft gasifier is an effective, relatively low energy consumption technology for hydrogen-rich gas production.

A novel biomass air gasification process for producing tar-free higher heating value fuel gas

Biomass is a promising sustainable energy source. A tar-free fuel gas can be obtained in a properly designed biomass gasification process. In the current study, a tar-free biomass gasification process by air was proposed. This concept was demonstrated on a lab-scale fluidized bed using sawdust under autothermic conditions. This lab-scale model gasifier combined two individual regions of pyrolysis, gasification, and combustion of biomass in one reactor, in which the primary air stream and the biomass feedstock were introduced into the gasifier from the bottom and the top of the gasifier respectively to prevent the biomass pyrolysis product from burning out. The biomass was initially pyrolyzed and the produced char was partially gasified in the upper reduction region of the reactor, and further, char residue was combusted at the bottom region of the reactor in an oxidization atmosphere. An assisting fuel gas and second air were injected into the upper region of the reactor to maintain elevated temperature. The tar in the flue gas entered the upper region of the reactor and was decomposed under the elevated temperature and certain residence time. This study indicated that under the optimum operating conditions, a fuel gas could be produced with a production rate of about 3.0 Nm 3/kg biomass and heating value of about 5000 kJ/Nm 3. The concentration of hydrogen, carbon monoxide and methane in the fuel gas produced were 9.27%, 9.25% and 4.21%, respectively. The tar formation could be efficiently controlled below 10 mg/Nm 3. The system carbon conversion and cold gasification efficiency reached above 87.1% and 56.9%, respectively. In addition, the investigation of energy balance for the scale-up of the proposed biomass gasification process showed that the heat loss could be recovered by approximately 23% of total energy input. Thus, partial fuel gas that was produced could be re-circulated and used to meet need of energy input to maintain the elevated temperature at the upper region of reactor for tar decomposition. It was predicted the heating value of product fuel gas would be 8000 kJ/Nm 3 if the system was scaled up.

Biomass gasification using capacitively coupled RF plasma technology

A laboratory-scale capacitively coupled radio frequency (RF) plasma pyrolysis reactor working in reduced pressure has been developed. Experiments have been performed to examine the characteristics of this RF plasma reactor and the products of biomass gasification. It was found that the electrode geometry, input power and reactor pressure were the key parameters affecting the plasma characteristics such as plasma length, temperature, and energy transfer efficiency. Biomass gasification using input power 1600–2000 W and reactor pressure 3000–8000 Pa produced a combustible gas consisted of H 2, CO, CH 4, CO 2 and light hydrocarbons as well as a pyrolytic char. On average, the gas yield can reach 66 wt% of the biomass feed. An energy balance analysis on the RF plasma pyrolysis system was also given.

An experimental study on biomass air–steam gasification in a fluidized bed

The characteristics of biomass air–steam gasification in a fluidized bed are studied in this paper. A series of experiments have been performed to investigate the effects of reactor temperature, steam to biomass ratio (S/B), equivalence ratio (ER) and biomass particle size on gas composition, gas yield, steam decomposition, low heating value (LHV) and carbon conversion efficiency. Over the ranges of the experimental conditions used, the fuel gas yield varied between 1.43 and 2.57 N m 3/kg biomass and the LHV of the fuel gas was between 6741 and 9143 kJ/N m 3. The results showed that higher temperature contributed to more hydrogen production, but too high a temperature lowered gas heating value. The LHV of fuel gas decreased with ER. Compared with biomass air gasification, the introduction of steam improved gas quality. However, excessive steam would lower gasification temperature and so degrade fuel gas quality. It was also shown that a smaller particle was more favorable for higher gas LHV and yield.

Air gasification of biomass in a downdraft fixed bed: A comparative study of the inorganic and organic products distribution

Air gasification of biomass in a downdraft fixed bed: A comparative study of the inorganic and organic products distribution

An Experimental Investigation of Alkali Removal from Biomass Producer Gas Using a Fixed Bed of Solid Sorbent

A bench-scale gasifier system composed of a fluidized-bed gasifier, high-temperature ceramic filter, and fixed-bed solid sorbent reactor was used to study the removal of alkali from a hot product gas stream. During a test conducted with an empty solid sorbent reactor, dry gas-phase concentrations of 28 ppmw K, 11 ppmw Na, and 1309 ppmw Cl were measured. Four subsequent tests utilized 2.4−3.4-mm-diameter particles of activated bauxite or emathlite in the solid sorbent reactor. Over these four tests, K concentrations ranged from 0.03 to 0.07 ppmw, and Na concentrations ranged from 0.2 and 0.9 ppmw at the exit of the solid sorbent reactor. Chlorine concentrations at the exit of the reactor were essentially unaffected. Hot-water leaching tests indicated that alkali capture by activated bauxite and emathlite was through physical adsorption and chemisorption, respectively.

Air Gasification of Biomass in a Downdraft Fixed Bed: A Comparative Study of the Inorganic and Organic Products Distribution

This paper deals with the gasification of agricultural residues such as almond shells and wood at high temperature (850 °C) in a small-scale gasification plant coupled with a reciprocated internal combustion engine. Detailed investigation of both organic (tar) and inorganic (NH3, HCN, metals, etc.) products distribution in the process streams are provided. This research aims to assess the existence of certain relations between feedstock composition and the observed products distribution in the steady state. Biomass feedstock is characterized for its elemental composition, its content of metallic species, and lignin, cellulose, and hemicellulose fractions. A different feedstock composition was found to be associated with some important variations in the process monitored parameters such as the gasification rate, the tar content, and the char yield in the flue gas. Also a relation was found between the relative amount of ammonia and cyanide species in the flue gas at the operating conditions of the gasifier (oxygen-to-biomass ratio and activated carbon support). Spectroscopic features of the sludgy condensate formed in the upper part of the gasifier during the early stage of the process together with the characterization of char, fly ash, and acidic species in the flue gas shed light on some mechanistic aspects of the gasification process.

98/03688 Catalytic tar removal from biomass producer gas with secondary air

98/03688 Catalytic tar removal from biomass producer gas with secondary air

98/01171 Catalytic tar removal from biomass producer gas with in situ catalyst regeneration: Lammers, G. and Beenackers, A. A. C. M. Biomass Energy Environ., Proc. Eur. Bioenergy Conf., 9th, 1996, 2, 1416–1422. Edited by Chartier, P., Elsevier, Oxford, UK

98/01171 Catalytic tar removal from biomass producer gas with in situ catalyst regeneration: Lammers, G. and Beenackers, A. A. C. M. Biomass Energy Environ., Proc. Eur. Bioenergy Conf., 9th, 1996, 2, 1416–1422. Edited by Chartier, P., Elsevier, Oxford, UK

98/00420 Catalytic tar removal from biomass producer gas with in situ catalyst regeneration

98/00420 Catalytic tar removal from biomass producer gas with in situ catalyst regeneration

Catalytic Gas Conditioning: Application to Biomass and Waste Gasification

Catalytic gas conditioning is a key step in producing clean syngas via gasification of heterogeneous materials. Our work has focused on the steam re-forming of naphthalene and orthodichlorobenzene as prototypes of polyaromatic hydrocarbons (PAHs) and halogenated aromatics. Subsequently, we have studied the conversion of tar present in the syngas derived from biomass and waste gasification. Steam re-forming of naphthalene was initially studied over a UCI GB-98 commercial catalyst in a fixed bed reactor operated at atmospheric pressure, in the temperature range 873−1123 K, with residence times of 0.31−0.82 s and steam to naphthalene molar ratios of 10−22. Although the catalyst is efficient, it suffers from a progressive drop in activity due to coke formation as well as weight loss (35% weight loss after 24 h on stream). To overcome deactivation and catalyst weight loss, a robust catalyst formulation has been developed. It has demonstrated excellent activity as well as reasonable time-on-stream and easy regeneration without significant loss of activity. Total conversion of naphthalene and dichlorobenzene has been observed at 1023 and 1123 K, respectively. The yields of dry gas in both cases have been higher than 90%. After 60 h on stream, the catalyst weight loss is less than 5%. This catalyst has also performed efficiently in the conversion of tar present in the producer gas from air gasification of biomass and mixed wastes.

Synthesis of liquid fuels from products of biomass gasification

Liquid hydrocarbons can be successfully produced from the product of air-biomass gasification by Fischer-Tropsch synthesis over cobalt catalysts. The presence of considerable concentrations of carbon dioxide and nitrogen in the reaction feed influences this process: carbon dioxide by reducing the probability of side reactions, and nitrogen by promoting the formation of diesel range hydrocarbons.

Chemical Equilibrium Computations for Gasification of Biomass to Produce Methanol

Gasification of biomass into synthesis gas is the first step in producing methanol from biomass. Catalytic conversion of the gas produced by the gasifier into methanol is strongly affected by the composition of the product gas. It is thus important to know what the gas composition would be under different gasification conditions and to be able to identify those conditions that would be optimal for methanol production. A computer program is developed to determine the equilibrium composition of biomass gasification products under various conditions. The theoretical influence of temperature, pressure, moisture, and equivalence ratio on gasification is analyzed. The equilibrium computations are used to define appropriate gasification conditions for methanol production and related gasification parameters. By judiciously adjusting certain gasification parameters, it appears that one can optimize the gas generated from biomass for subsequent synthesis into methanol. Energy balances and theoretical methanol yield...