No abstract

The interaction between alkali chloride and sulfur oxides has important implications for deposition and corrosion in combustion of biomass. In the present study, the sulfation of particulate KCl (90−125 μm) by SO 2 was studied in a fixed bed reactor in the temperature range 673−1023 K and with reactant concentrations of 500−3000 ppm SO 2 , 1−20% O 2 , and 4−15% H 2 O. The degree of sulfation was monitored by measuring the formation of HCl. Analysis of the solid residue confirmed that the reaction proceeds according to a shrinking core model and showed the formation of an eutectic at higher temperatures. On the basis of the experimental results, a rate expression for the sulfation reaction was derived. The model compared well with literature data for sulfation of KCl and NaCl, and the results indicate that it may be applied at even higher SO 2 concentrations and temperatures than those of the present study. Simulations of sulfation of KCl particles with different size indicate that only for very small KCl particles, below 1 μm, a considerable in-flight sulfation is achievable at the short gas residence times typical of combustion systems.

No abstract

No abstract

Two new sulfated saponins (1 and 2) were isolated from a butanol-soluble extract of the roots of Gypsophila bermejoi and were identified by a combination of chemical degradation and spectral methods as the 3beta-sulfate ester of gypsogenin 28-O-beta-D-glucopyranosyl(1-->2)-[beta-D-glucopyranosyl(1-->6)]-beta -D-glucopyranoside (1), and the 23-sulfate ester of hederagenin 28-O-beta-D-glucopyranosyl(1-->2)-[beta-D-glucopyranosyl(1-->6)]-beta -D-glucopyranoside (2), respectively. Plants of the genus Gypsophila (Caryophyllaceae) are important industrially because of the capacity of their saponin constituents to behave like natural detergents.1 Saponins from this genus are based on oleanolic acid (3-hydroxyolean-12-en-28-oic acid), with gypsogenin being the main pentacyclic triterpenoidal aglycon found. In general, this aglycon is substituted at the C-3 hydroxyl and/or C-28 carboxylic acid groups by saccharide units.2

Biomass is presented as a valuable alternative to partially substitute fossil fuels to decrease CO 2 emissions. Two different energy crops (cynara and poplar) were co-fired with a South African coal in a 500 kW th pulverized fuel pilot plant to analyze their fouling tendency at different shares. Results were also compared to a pine residue, and finally, the coal was substituted in cynara co-firing by a high sulfur sub-bituminous coal to see its effect on ash deposition. Deposit samples from a deposition probe were analyzed with scanning electron microscopy/energy-dispersive spectrometry and inductively coupled plasma−optical emission spectroscopy techniques, and results were evaluated together with different theoretical indexes. No operational problems were found in the tested shares (up to 15% biomass energy based). Nevertheless, coal appeared to have conclusive influence on ash deposition, which was more important for the sub-bituminous coal tested. Alkali chlorides were destroyed in all of the cases, because no chlorine was found in deposits (even though cynara has a high Cl content). Main differences among biomasses lied in the inorganic content, which was higher for cynara than for the others.

Gypsophila bermejoi G. López is an allopolyploid species derived from the parental G. struthium L. subsp. struthium and G. tomentosa L. All these plants are gypsophytes endemic to the Iberian Peninsula of particular ecological, evolutionary and biochemical interest. In this study, we present evidence of a possible repression on the process of G. bermejoi speciation by climatic factors. We modelled the ecological niches of the three taxa considered here using a maximum entropy approach and employing a series of bioclimatic variables. Subsequently, we projected these models onto the geographical space of the Iberian Peninsula in the present age and at two past ages: the Last Glacial Maximum and the mid-Holocene period. Furthermore, we compared these niches using the statistical method devised by Warren to calculate their degree of overlap. We also evaluated the evolution of the bioclimatic habitat suitability at those sites were the soil favors the growth of these species. Both the maximum entropy model and the degree of overlap indicated that the ecological behavior of the hybrid differs notably from that of the parental species. During the Last Glacial Maximum, the two parental species appear to take refuge in the western coastal strip of the Peninsula, a region in which there are virtually no sites where G. bermejoi could potentially be found. However, in the mid-Holocene period the suitability of G. bermejoi to sites with favorable soils shifts from almost null to a strong adaptation, a clear change in this tendency. These results suggest that the ecological niches of hybrid allopolyploids can be considerably different to those of their parental species, which may have evolutionary and ecologically relevant consequences. The data obtained indicate that certain bioclimatic variables may possibly repress the processes by which new species are formed. The difference in the ecological niche of G. bermejoi with respect to its parental species prevented it from prospering during the Last Glacial Maximum. However, the climatic change in the mid-Holocene period released this block and as such, it permitted the new species to establish itself. Accordingly, we favor a recent origin of the current populations of G. bermejoi.

Agropellets are presented as a suitable product to be produced in certain agro-industries which could become Integrated Biomass Logistic Centres (IBLC) by taking advantage of its current resources during those periods in which their facilities are underused. Wheat straw and maize stalk were selected to be blended with forestry wood in an agro-industry dedicated to animal feed production. The materials were characterized to assess the quality of the input material. Taking into account the former, different pellets (blends of woody and herbaceous biomass) were produced and tested in a fixed bed reactor in order to study their combustion behaviour. Additionally, several predictive indexes were also calculated to assess sintering and deposition occurrence probability. Ash sintering degree was found to be directly related to composition and highly dependent on Si content. Moreover, an increase of the wood content in the blend did not proportionally imply a higher quality of the final blend, as would be expected. Regarding deposition, due to the high number of factors involved in this phenomenon, it has not been possible to draw clear conclusions. To do this, it was necessary to delve into the deposition mechanisms, which is addressed in the second part of this paper. Thus, despite the appearance of sintering and deposition phenomena, the combustion behaviour was satisfactory in the test carried out. Additionally, it has been demonstrated that agro-industries can act as IBLCs, producing blended pellet for the energy market that aligns with the standard ISO 17225-6.