Investigation into the applicability of Bond Work Index (BWI) and Hardgrove Grindability Index (HGI) tests for several biomasses compared to Colombian La Loma coal

With increasing quantities of biomass being combusted in coal fired power stations, there is an urgent need to be able to predict the grindability of biomass in existing coal mills, but currently no standard biomass grindability test exists. In this study, the applicability of the Hardgrove Grindability Index (HGI) and Bond Work Index (BWI) as standard grindability tests for biomass were investigated for commercially sourced wood pellets, steam exploded pellets, torrefied pellets, sunflower pellets, eucalyptus pellets, miscanthus pellets, olive cake and Colombian La Loma coal. HGI predicts the behaviour of fuels in vertical spindle mills and BWI for tube and ball mills. Compared to La Loma (HGI of 46), all biomasses tested performed poorly with low HGI values (14–29). Miscanthus pellets had the highest BWI or Wi at 426 kW h/t. Despite similar HGI values, some untreated biomasses showed lower BWI values (Eucalyptus pellets Wi 87 kW h/t, HGI 22) compared to others (sunflower pellets Wi 366 kW h/t, HGI 20). Torrefied pellets had the lowest Wi (16 kW h/t), with La Loma coal at 23 kW h/t. Wood, miscanthus and sunflower pellets exhibited mill choking during the BWI test, as the amount of fines produced did not increase with an increasing revolution count. An approximate correlation between HGI and BWI was found for the biomass samples which did not experience mill choking in the BWI test. Milling results in this paper suggest that biomass pellets should be composed of pre-densified particles close to the target size in order to minimise the energy use in mills and possibility of mill choking. Our findings would also suggest that the BWI is a valid test for predicting the potential for mill choking of biomass in a tube and ball mill. HGI, however, appears to be a poor method of predicting the grindability of biomass in vertical spindle mills. A new standard grindability test is required to test the grindability of biomasses in such mills

Experiments on torrefied wood pellet: study by gasification and characterization for waste biomass to energy applications

Samples of torrefied wood pellet produced by low-temperature microwave pyrolysis were tested through a series of experiments relevant to present and near future waste to energy conversion technologies. Operational performance was assessed using a modern small-scale downdraft gasifier. Owing to the pellet's shape and surface hardness, excellent flow characteristics were observed. The torrefied pellet had a high energy density, and although a beneficial property, this highlighted the present inflexibility of downdraft gasifiers in respect of feedstock tolerance due to the inability to contain very high temperatures inside the reactor during operation. Analyses indicated that the torrefaction process had not significantly altered inherent kinetic properties to a great extent; however, both activation energy and pre-exponential factor were slightly higher than virgin biomass from which the pellet was derived. Thermogravimetric analysis-derived reaction kinetics (CO2 gasification), bomb calorimetry, proximate and ultimate analyses, and the Bond Work Index grindability test provided a more comprehensive characterization of the torrefied pellet's suitability as a fuel for gasification and also other combustion applications. It exhibited significant improvements in grindability energy demand and particle size control compared to other non-treated and thermally treated biomass pellets, along with a high calorific value, and excellent resistance to water

Benefits of dry comminution of biomass pellets in a knife mill

The potential benefits of dry comminution in a knife mill for a diverse range of biomass 6 pellets are explored. The impact of dry comminution on energy consumption, particle size and shape, 7 is examined as well as the link between milling and mechanical durability. Biomass pellet comminution 8 energy was significantly lower (19.3-32.5 kW h t-1 [fresh] and 17.8-23.2 kW h t-1 [dry]) than values 9 reported in literature for non-densified biomass in similar knife mills. The impact of drying was found 10 to vary by feedstock. Dry grinding reduced milling energy by 38% for mixed wood pellets, but only 2% 11 for steam exploded pellets. Particle size and shape, particle distribution dispersion, and distribution 12 shape parameters changes between fresh and dry milling were also material dependent. Von Rittinger 13 analysis showed that to maximise mill throughput, pellets should be composed of particles which can 14 pass through the screen and thus have a neutral size change. A strong correlation was found between 15 pellet durability and energy consumption for fresh biomass pellets. Dry grinding has the potential to 16 significantly reduce energy consumption without compromising the product particle size, as well as 17 enhancing product quality and optimising biomass pellet comminution and combustion

Isoform-selective interaction of the adaptor protein Tks5/FISH with Sos1 and dynamins

The adaptor protein Tks5/FISH (tyrosine kinase substrate 5/five SH3 domains, hereafter termed Tks5) is a crucial component of a protein network that controls the invasiveness of cancer cells and progression of Alzheimer's disease. Tks5 consists of an amino-terminal PX domain that is followed by five SH3 domains (SH3A-E), and two different splice variants are expressed. We identified son of sevenless-1 (Sos1) as a novel binding partner of Tks5 and found colocalization of Tks5 with Sos1 in human epithelial lung carcinoma (A549) cells and in podosomes of Src-transformed NIH 3T3 cells. We observe synergistic binding of SH3A and SH3B to Sos1 when peptide arrays are used, indicating that the tandem SH3A and SH3B domains of Tks5 can potentially bind in a superSH3 binding mode, as was described for the homologous protein p47phox. These results are further corroborated by pull-down assays and isothermal titration calorimetry showing that both intact SH3 domains are required for efficient binding to the entire proline-rich domain of Sos1. The presence of a basic insertion between the SH3A and SH3B domains in the long splice variant of Tks5 decreases the affinity to Sos1 isoforms about 10-fold as determined by analytical ultracentrifugation. Furthermore, it leads to an alteration in the recognition of binding motifs for the interaction with Sos1: While the insertion abrogates the interaction with the majority of peptides derived from the proline-rich domains of Sos1 and dynamin that are recognized by the short splice isoform, it enables binding to a different set of peptides including a sequence comprising the splice insertion in the long isoform of Sos1 (Sos1_2). In the absence of the basic insertion, Tks5 was found to bind a range of Sos1 and dynamin peptides including conventional proline-rich motifs and atypical recognition sequences. Hereby, the tandem SH3 domains in Tks5 employ two distinct types of binding modes: One class of peptides is recognized by single SH3 domains, whereas a second class of peptides requires the presence of both domains to bind synergistically. We conclude that the tandem SH3A and SH3B domains of Tks5 constitute a versatile module for the implementation of isoform-specific protein-protein interactions