Combustion of Pulverized Biomass Crop Residues and Their Explosion Characteristics

Two Pakistani crop residues bagasse (B) and wheat straw (WS), both with high ash content, were milled to <63µm and the ISO 1 m3 explosion equipment was used to investigate flame propagation in the dispersed cloud of pulverised biomass. Their turbulent flame speed was measured and the Kst (dP/dtmaxV1/3) and comparison was made with two pulverised coal samples. Minimum Explosion Concentration (MEC) values for B and WS were, in terms of the burnt dust mass equivalence ratio (Ø) 0.2Ø to 0.3Ø , which was leaner than for the coal samples. These MEC were lower than had previously been determined using the Hartmann explosion tube, and this was considered to be due to the 10 kJ ignition energy in the 1 m3 equipment and 4J spark energy in the Hartmann explosion tube, which extended the lean limit in the 1 m3 equipment. Peak turbulent flame speeds were 3.8 m/s for B and 3.0 m/s for WS compared with 3.5–5.2 m/s for the two coal samples. The peak Kst was 103 bar m/s for bagasse and 80 bar m/s for wheat straw and the two coal samples had peak Kst of 78 and 120 bar m/s. Overall the agricultural biomass and coal samples had a similar range of reactivity. Thus these agricultural crop residues are a viable renewable fuel for co-firing with coal or as 100% biofuel operation of steam power plants

Flame speed and Kst reactivity data for pulverised corn cobs and peanut shells.

Power generation using waste material from the processing of agricultural crops can be a viable biomass energy source. However, there is scant data on their burning properties and this work presents flame speed and explosion Kst data for two agricultural waste materials: corn cobs and peanut shells. Both parameters were measured on the ISO 1 m3 dust explosion equipment. Two coarse size fractions of corn cobs (CC) and peanut shells (PS) of size less than 500 μm were tested using the Leeds 1 m3 vessel and were compared with two pulverized coal samples. This is typical of the size fraction used in pulverized coal power stations and of pulverized biomass currently used in power generation. The explosion parameters minimum explosive concentration (MEC), rate of pressure rise (dP/dt), deflagration constant (Kst), peak to initial pressure rise (Pm/Pi), turbulent and laminar flame speeds were determined using a calibrated hemispherical disperser in the 1 m3 vessel. MEC were measured in the range of 0.6-0.85 in terms of burnt equivalence ratio, Øburnt, which were comparable to the coal samples. The measured Kst (25-60 bar m/s) and turbulent flame speeds (~1.3 m/s) were lower than for coal, which was a reflection of the lower calorific value. These results showed that these crop residues are technically feasible power plant fuels to burn alongside coal or as a renewable biofuel on their own

Flame Propagation of Pulverised Biomass Crop Residues and their Explosion Characteristics

Pulverised agricultural crop residues were investigated using the ISO 1 m3 turbulent explosion vessel. This was modified to enable the spherical flame propagation flame speed and the heat release rate in MW/m2 to be determined. From the turbulent flame speed, the laminar flame speed and laminar burning velocity and global heat release, MW/m2, were determined. In addition the equipment was used to determine the biomass explosibility, Kst (= dP/dtmaxV1/3), and the minimum explosion concentration (MEC). Two Pakistani crop residues bagasse (B) and wheat straw (WS) were investigated. Particle size distribution, elemental and proximate analysis and surface morphology for the raw powders and for their post explosion residues were carried out. It was found that these crop residues have explosibility characteristics comparable to wood biomass powders. MEC values as low as equivalence ratios of 0.18 to 0.3 were found which were lower than for gaseous hydrocarbons, but similar to other measurements for biomass using the Hartmann explosibility equipment. Peak turbulent flame speeds were measured at 3-4 m/s. There was a significant post explosion residue of unburned material which was shown to have an increase in char content relative to the raw biomass, while the volatile content was reduced. The BET surface area of the post explosion residue of bagasse was higher than that of the wheat straw residue, showing a higher release of volatiles for bagasse with a more porous char residue in the burnout indicating higher reactivity. These crop residues are a viable renewable fuel for existing coal power plants or as a basis for a new generation of small scale steam power generators in Pakistan

The Burning Velocity of Pulverised Biomass: The Influence of Particle Size

The use of pulverised biomass as a replacement for coal in power generation is a major source of renewable electricity in the UK. However, there is little data on flame propagation rates for pulverised biomass and this makes it difficult to design burners and model these flames using the traditional burning velocity approach. An ISO 1 m3 dust explosion vessel was modified to enable constant pressure spherical expanding turbulent flame speeds, ST, to be measured for pulverised biomass. The turbulence generated by the new dust injection system was calibrated using turbulent and laminar gas explosions and this enabled the dust laminar flame speed, SL, to be determined from ST. The burnt gas expansion ratio, EP, was determined from the peak pressure rise and this enabled the laminar burning velocity, Su, to be determined from the measured ST. The results showed for a range of biomass that the peak ST was in the range 3–5.5 m/s. The laminar burning velocity for 26 biomass and two coal samples and were very low at 0.1 – 0.2 m/s for the most reactive mixture, depending on the biomass particle size

Ignition sensitivity of solid fuel mixtures

Due to both environmental concerns and the depletion of the reserves of fossil fuels, alternative and more environmentally friendly fuels, such as biomass and waste products, are being considered for partial or full fossil fuel replacement. The main disadvantage of these products is their lower energy density compared to fossil fuels. To deal with this several heat and power generation facilities are co-firing fuel mixtures. These processes involve mixtures of flammable dusts whose ignitability and explosibility characteristics are not known and therefore present un-quantified safety risk to the new technologies. This study reports on these risks and on the reactivity characteristics of two and three components dust mixtures of coal/sewage-sludge/torrefied-wood-pellet. In particular chemical composition, ignition sensitivity parameters (including minimum ignition energy, minimum ignition temperature on a layer, minimum explosive concentration) and flame speed have been determined. In all cases the measured parameters for the mixtures were within the range defined by the lower and upper value of the constituent. However, the expected values do not agree with the experimentally obtained ones, providing more relaxed values than the ones needed on this facilities

Identification of Heterozygous Single- and Multi-exon Deletions in IL7R by Whole Exome Sequencing

PURPOSE: We aimed to achieve a retrospective molecular diagnosis by applying state-of-the-art genomic sequencing methods to past patients with T-B+NK+ severe combined immunodeficiency (SCID). We included identification of copy number variations (CNVs) by whole exome sequencing (WES) using the CNV calling method ExomeDepth to detect gene alterations for which routine Sanger sequencing analysis is not suitable, such as large heterozygous deletions. METHODS: Of a total of 12 undiagnosed patients with T-B+NK+ SCID, we analyzed eight probands by WES, using GATK to detect single nucleotide variants (SNVs) and small insertions and deletions (INDELs) and ExomeDepth to detect CNVs. RESULTS: We found heterozygous single- or multi-exon deletions in IL7R, a known disease gene for autosomal recessive T-B+NK+ SCID, in four families (seven patients). In three families (five patients), these deletions coexisted with a heterozygous splice site or nonsense mutation elsewhere in the same gene, consistent with compound heterozygosity. In our cohort, about a quarter of T-B+NK+ SCID patients (26%) had such compound heterozygous IL7R deletions. CONCLUSIONS: We show that heterozygous IL7R exon deletions are common in T-B+NK+ SCID and are detectable by WES. They should be considered if Sanger sequencing fails to detect homozygous or compound heterozygous IL7R SNVs or INDELs

Allogeneic hematopoietic stem cell transplantation for severe, refractory juvenile idiopathic arthritis.

Patients with juvenile idiopathic arthritis (JIA) can experience a severe disease course, with progressive destructive polyarthritis refractory to conventional therapy with disease-modifying antirheumatic drugs including biologics, as well as life-threatening complications including macrophage activation syndrome (MAS). Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a potentially curative immunomodulatory strategy for patients with such refractory disease. We treated 16 patients in 5 transplant centers between 2007 and 2016: 11 children with systemic JIA and 5 with rheumatoid factor-negative polyarticular JIA; all were either refractory to standard therapy, had developed secondary hemophagocytic lymphohistiocytosis/MAS poorly responsive to treatment, or had failed autologous HSCT. All children received reduced toxicity fludarabine-based conditioning regimens and serotherapy with alemtuzumab. Fourteen of 16 patients are alive with a median follow-up of 29 months (range, 2.8-96 months). All patients had hematological recovery. Three patients had grade II-IV acute graft-versus-host disease. The incidence of viral infections after HSCT was high, likely due to the use of alemtuzumab in already heavily immunosuppressed patients. All patients had significant improvement of arthritis, resolution of MAS, and improved quality of life early following allo-HSCT; most importantly, 11 children achieved complete drug-free remission at the last follow-up. Allo-HSCT using alemtuzumab and reduced toxicity conditioning is a promising therapeutic option for patients with JIA refractory to conventional therapy and/or complicated by MAS. Long-term follow-up is required to ascertain whether disease control following HSCT continues indefinitely

Treosulfan, Fludarabine Conditioning for HSCT in Children with Primary Immunodeficiency: UK Experience

We previously published results of 70 children who received treosulfan with cyclophosphamide (30) or fludarabine (40) before haematopoietic stem cell transplantation (HSCT) for Primary Immunodeficiency (PID). Toxicity was lower and T cell chimerism better in those receiving fludarabine, but numbers were relatively small and follow-up short. We now report outcome of 160 children who received homogeneous conditioning with treosulfan, fludarabine mostly with alemtuzumab (n=124). Median age at transplant was 1.36 years (0.09-18.25). Donors were: matched unrelated, 73; 1-3 antigen mismatched unrelated, 54; matched sibling, 12; other matched family, 17; haploidentical, 4. Stem cell source was: peripheral blood stem cells (PBSCs), 70; Bone marrow, 49; Cord Blood, 41. Median follow up was 4.3 years (0.8-9.4). Overall survival was 83%. There was no veno- occlusive disease. Seventy-four (46%) had acute GVHD, but only 14(9%) greater than grade II. Four patients were successfully retransplanted for graft loss or poor immune reconstitution. One further patient who rejected the graft, died. There was no association between T cell chimerism > 95% and stem cell source, but a significant association with myeloid chimerism > 95% and use of PBSC without an increased risk of significant GVHD compared to other sources. All 11 patients with severe combined immunodeficiency diagnosed at birth are alive with up to 8.7 years follow up. Long-term studies are required to determine late gonadotoxic effects and pharmacokinetic studies are needed to identify whether specific targeting is advantageous. The combination of treosulfan, fludarabine and alemtuzumab gives excellent results in HSCT for PID