Solid Biomass Gasification Research Articles

Hydrogen rich gas production by thermocatalytic decomposition of kenaf biomass

Kenaf ( Hibiscus cannabinus L.), a well known energy crop and an annual herbaceous plant grows very fast with low lodging susceptibility was used as representative lignocellulosic biomass in the present work. Thermocatalytic conversions were performed by aqueous phase reforming (APR) of kenaf hydrolysates and direct gasification of solid biomass of kenaf using 5% Pt on activated carbon as catalyst. Hydrolysates used in APR experiments were prepared by solubilization of kenaf biomass in subcritical water under CO 2 gas pressure. APR of kenaf hydrolysate with low molecular weight polysaccharides in the presence of the reforming catalyst produced more gas compared to the hydrolysate that had high molecular weight polysaccharides. APR experiments of kenaf biomass hydrolysates and glucose, which was used as a simplest biomass model compound, in the presence of catalyst produced various amounts of gas mixtures that consisted of H 2, CO, CO 2, CH 4 and C 2H 6. The ratios of H 2 to other gases produced were 0.98, 1.50 and 1.35 for 150 °C and 250 °C subcritical water-treated kenaf hydrolysates and glucose, respectively. These ratios indicated that more the degraded organic content of kenaf hydrolysate the better selectivity for hydrogen production. Although APR of 250 °C-kenaf hydrolysate resulted in similar gas content and composition as glucose, the gas volume produced was three times higher in glucose feed. The use of solid kenaf biomass as starting feedstock in APR experiments resulted in less gas production since the activity of catalyst was lowered by solid biomass particles.

H 2 rich product gas by steam gasification of biomass with in situ CO 2 absorption in a dual fluidized bed system of 8 MW fuel input

The steam gasification of solid biomass by means of the absorption enhanced reforming process (AER process) yields a high quality product gas with increased hydrogen content. The product gas can be used for a wide range of applications which covers the conventional combined heat and power production as well as the operation of fuel cells, the conversion into liquid fuels or the generation of synthetic natural gas and hydrogen. On the basis of a dual fluidized bed system, steam gasification of biomass is coupled with in situ CO 2 absorption to enhance the formation of hydrogen. The reactive bed material (limestone) used in the dual fluidized bed system realizes the continuous CO 2 removal by cyclic carbonation of CaO and calcination of CaCO 3. Biomass gasification with in situ CO 2 absorption has been substantially proven in pilot plant scale of 100 kW fuel input. The present paper outlines the basic principles of steam gasification combined with the AER process the investigations in reactive bed materials, and concentrates further on the first time application of the AER process on industrial scale. The first time application has been carried out within an experimental campaign at a combined heat and power plant of 8 MW fuel input. The results are outlined with regard to the process conditions and achieved product gas composition. Furthermore, the results are compared with standard steam gasification of biomass as well as with application of absorption enhanced reforming process at pilot plant scale.

Fluidized Bed Steam Gasification of Solid Biomass - Performance Characteristics of an 8 MWth Combined Heat and Power Plant

The work focuses on a dual fluidized bed gasification technology that is successfully operated for combined heat and power production at a scale of 8 MWth in Guessing/Austria since 2002. The reactor concept consists of a circulating fluidized bed system with a steam-fluidized bubbling bed integrated into the solids return loop. Accompanying the operation of the commercial scale plant, parameter models have been developed and validated by comparison to measured data. As the models naturally fulfill mass and energy balances, the simulation also allows the validation of measurement data. The behaviour of the plant is studied by carrying out variations of selected parameters. Evaluation of different plant operation cases yields correlations between process variables. The solids circulation rate is shown versus riser exit velocity. Fuel water content and gasification temperature significantly influence global plant performance. Simulation predicts the efficiency of the existing power plant in optimized operation. Finally, part load behaviour is investigated and performance maps of the CHP plant are presented. High fuel water content at high gas engine load results in high gas velocities in the riser (erosion limit) and higher heat ratio in the produced energy. It is concluded that CHP-concepts based on fluidized bed steam gasification can reach high electric efficiencies and high overall fuel utilization rates even at small plant capacities of about 10 MWth.

In-Situ CO2-Absorption in a Dual Fluidized Bed Biomass Steam Gasifier to Produce a Hydrogen Rich Syngas

Within the last years renewable energy sources came more and more into the public focus. Steam gasification of solid biomass yields high quality producer gases that can be used for efficient combined heat and power production (CHP) and as a renewable resource for chemical syntheses. The dual fluidized bed steam gasification technology provides the necessary heat for steam gasification by circulating hot bed material that is heated in a second fluidized bed reactor by combustion of residual biomass char. The hydrogen content in producer gas of such gasifiers is about 40vol% (dry basis). Addition of carbonates to the bed material and adequate adjustment of operation conditions in the reactors allow selective transport of CO2 from gasification to combustion zone (Absorption Enhanced Reforming – AER concept). An 8MW (fuel power) CHP plant successfully demonstrates gasification in Guessing, Austria since 2002. A process development unit (100 kW fuel power) has been recently operated to investigate the potential of the selective CO2 transport achieving a H2 content of up to 75vol% (dry basis) in the producer gas. No significant increase in tar formation occurs despite the low gasification temperatures (600-700°C). It can be shown, that the selective transport of CO2 yields high hydrogen contents in the producer gas and the possibility of operating at lower temperatures increases the efficiency of energy conversion.

03/01799 Method and device for gasification of solid biomass fuel: Shionotani, K. et al. Jpn. Kokai Tokkyo Koho JP 2002 285,172 (Cl. C10J3/00), 3 Oct 2002, Appl. 2001/89,854. (In Japanese)

03/01799 Method and device for gasification of solid biomass fuel: Shionotani, K. et al. Jpn. Kokai Tokkyo Koho JP 2002 285,172 (Cl. C10J3/00), 3 Oct 2002, Appl. 2001/89,854. (In Japanese)

99/01413 Hot corrosion of the steel grades 12Ch1MF, 13CrMo4-4 and 10CrMo9-10 in a pulverized coal boiler at a metal temperature

Although biomethanol production has attracted most of the attention in the past years, there is a current trend for the synthesis of higher alcohols (i.e. ethanol, plus C3–C4) from biomass gasification. These compounds could be used directly as fuel or fuel additives for octane or cetane number enhancement. These also serve as important intermediates for the chemical industry. In this paper a comparison is performed between the different process configurations a higher alcohols production plant from biomass gasification can take. These options are modelled in Aspenplus™; all steps and important unit operations are presented with the aim to correctly evaluate the peripheral energy requirements and conclude with the overall thermodynamic limitations of the processes. The differentiation between black liquor and solid biomass gasification, the type of catalyst employed, and the effect of the recycling scheme adopted for the reutilization of unreacted syngas are evaluated. The design has to cope with the limited yields and poor selectivity of catalysts developed so far. The gas cleaning is different depending on the different requirements of the catalysts as far as H2S purity. The process modelling results reveal that the hydrogenation of CO to higher alcohols is favoured by high pressure, temperature around 325 °C and high reactor residence times. A biorefinery using modified Fisher–Tropsch (FT) catalysts (MoS2) prevail over modified MeOH catalyst (Cu–Zn based) for HA production. The efficiency of HA production in HHV terms can reach up to 25%.