Reactors for Catalytic Methanation in the Conversion of Biomass to Synthetic Natural Gas (SNG)

Production of Synthetic Natural Gas (SNG) from biomass is an important step to decouple the use of bioenergy from the biomass production with respect to both time and place. While anaerobic digestion of wet biomass is a state-of-the art process, wood gasification to producer gas followed by gas cleaning and methanation has only just entered the demonstration scale. Power-to-Gas applications using biogas from biomass fermentation or producer gas from wood gasification as carbon oxide source are under development. Due to the importance of the (catalytic) methanation step in the production of SNG from dry biomass or within Power-to-Gas applications, the specific challenges of this step and the developed reactor types are discussed in this review

Online elemental analysis of process gases with ICP-OES: A case study on waste wood combustion

A mobile sampling and measurement system for the analysis of gaseous and liquid samples in the field was developed. An inductively coupled plasma optical emission spectrometer (ICP-OES), which is built into a van, was used as detector. The analytical system was calibrated with liquid and/or gaseous standards. It was shown that identical mass flows of either gaseous or liquid standards resulted in identical ICP-OES signal intensities. In a field measurement campaign trace and minor elements in the raw flue gas of a waste wood combustor were monitored. Sampling was performed with a highly transport efficient liquid quench system, which allowed to observe temporal variations in the elemental process gas composition. After a change in feedstock an immediate change of the element concentrations in the flue gas was detected. A comparison of the average element concentrations during the combustion of the two feedstocks showed a high reproducibility for matrix elements that are expected to be present in similar concentrations. On the other hand elements that showed strong differences in their concentration in the feedstock were also represented by a higher concentration in the flue gas. Following the temporal variations of different elements revealed strong correlations between a number of elements, such as chlorine with sodium, potassium and zinc, as well as arsenic with lead, and calcium with strontium. (c) 2012 Elsevier Ltd. All rights reserved

Online elemental analysis of process gases with ICP-OES: A case study on waste wood combustion

A mobile sampling and measurement system for the analysis of gaseous and liquid samples in the field was developed. An inductively coupled plasma optical emission spectrometer (ICP-OES), which is built into a van, was used as detector. The analytical system was calibrated with liquid and/or gaseous standards. It was shown that identical mass flows of either gaseous or liquid standards resulted in identical ICP-OES signal intensities. In a field measurement campaign trace and minor elements in the raw flue gas of a waste wood combustor were monitored. Sampling was performed with a highly transport efficient liquid quench system, which allowed to observe temporal variations in the elemental process gas composition. After a change in feedstock an immediate change of the element concentrations in the flue gas was detected. A comparison of the average element concentrations during the combustion of the two feedstocks showed a high reproducibility for matrix elements that are expected to be present in similar concentrations. On the other hand elements that showed strong differences in their concentration in the feedstock were also represented by a higher concentration in the flue gas. Following the temporal variations of different elements revealed strong correlations between a number of elements, such as chlorine with sodium, potassium and zinc, as well as arsenic with lead, and calcium with strontium. (c) 2012 Elsevier Ltd. All rights reserved

Gasification of Hay in a Bench Scale Fluidised Bed Reactor with Emphasis on the Suitability for Gas Turbines

Thermal gasification of pasture plants (hay) is so far considered as difficult mainly due to the high amount of inorganics (ash, alkalis). Under certain circumstances it could be an additional resource for power production. There has been some experiments to test hay in gasification plants but most lack inorganic analysis. A bubbling fluidized bed was set up and gasification experiments with extensive analysis of the gas composition was conducted. Dolomite, silica and alumina particles were used as bed material. Silica proved to work successfully at 700 degrees C. Ash experiments showed that at higher temperatures silica forms compounds that melt and lead to unstable gasification conditions. Dolomite proved to be not stable enough for fluidised bed conditions, since it was ground down to smaller particles and subsequently entrained. Alumina was the best bed material tested, which was used up to 750 degrees C with good results. The longest run was 10 h at 750 degrees C without defluidisation. Despite the low temperature in the process the bulk tar concentration was low. The heating value of the gas was good (4-6 MJ m(-3)). The concentration of sodium and potassium in the syngas after the warm gas filter at 400 C is low enough towards a cofiring IGCC application with 10% energy input from hay. (C) 2012 Elsevier Ltd. All rights reserved

Sulphur poisoning of Ni catalysts in the SNG production from biomass: A TPO/XPS/XAS study

Ni-based catalysts are prone to deactivation (poisoning) of their active surface sites by sulphur and carbon species contained in the gas fed to the reactor. This study focuses on Ni/Al2O3-based catalyst samples which had allegedly been deactivated by sulphur poisoning. The samples had been collected from a 10 kW methanation reactor fed with producer gas from the industrial biomass gasifier in Gussing (Austria). The samples allowed intensive investigation using several analytical tools to identify the chemical nature (inorganic, organic) of the S-poisoning species. Temperature-programmed oxidation (TPO) allowed quantification of the sulphur content, but not the identification of the S species responsible. S 2p X-ray photoelectron spectroscopy (XPS) pointed at the presence of sulphide and sulphate, but the data were too noisy to reach more specific conclusions. Ni K-edge X-ray absorption spectroscopy (XAS) in the fine structure (EXAFS) region suggested the presence of elemental or thiophenic sulphur, but the contribution was masked heavily by other backscattering paths. Only S Kedge analysis in the near edge (XANES) region showed unambiguously that the catalyst could not have been deactivated by inorganic H2S only. This conclusion is supported by S K-edge XANES results with model catalysts which had either been poisoned by H2S or thiophene (C4H4S), representing a cyclic, aromatic S compound. Short-term H2S poisoning in the absence of air led to a white-line position characteristic for sulphide (2470 eV), whereas with thiophene the white-line position started at 3 eV higher energy. The XANES signatures changed with the catalyst samples after contacting air, but remained unique for each of the two S-poison types studied here. (C) 2009 Elsevier B.V. All rights reserved

Impact of syngas from biomass gasification on solid oxide fuel cells: A review study for the energy transition

Operating solid oxide fuel cells (SOFC) with gas from biomass gasification ensures a combined heat and power system with a less complex gas cleaning and an efficient use of biogenic resources. The main challenge and obstacle for the application of SOFCs with bio-syngas is the degradation of Nickel anode caused by carbon deposition, Nickel re-oxidation and contaminants such as tar and sulfur. Understanding the degradation mechanisms, identifying the optimal operation conditions and developing advanced SOFC materials, regeneration methods and diagnosis tools are essential for a stable, efficient and eco-friendly system. This work reviews the current development in terms of the deterioration of cell anodes, the underlying materials sciences, operation of coupled system, the economic feasibility and further approaches of efficiency elevation