A novel method of pure oxy-fuel circulating fluidized bed combustion with zero recirculation flue gas : experimental validation

Applying oxy-fuel combustion requires more advanced combustion control methods to avoid inadmissible high flam temperature. In fluidized beds and pulverized unites, enhanced heat transfer and recirculation flue gas are used. On other hand, higher oxygen concentration has pluses viz. better heat transfer, higher efficiency, compact setup and lower installation and operating costs. In pulverized power unites, pure oxy-fuel combustion is used with 100% O2 in the oxidant. In contrast, the highest experimental O2 % in oxy-fuel circulating fluidized bed (CFB) combustor is 70%. To the best of authors’ knowledge, there is no single CFB power plant operating under pure oxygen condition. In this work, we are aiming to use pure oxygen for oxy-CFB combustion, with new temperature controlling method for CFBs depending on combustion staging by fuel staging rather than using RFG. Fuel staging allows controlling combustion and varying SR. At the first stage, the used oxidant is 100% O2, and fuel is fed to achieve over SR (λ>1), where the excess oxidant absorbs heat and does not take a part in the reaction. The products of the first stage are reach of O2 and subsequently it is used as an oxidant for the second stage. For validation, a series of experiments are conducted using mini-CFB, and an oxidant of 100% O2 concentration is used with three SR ratios λ=1.25, 2.0, and 3.0. The resulted average temperatures along the riser for biomass are 1031°C, 950°C, and 798°C; and for coal 1129 °C, 1051 °C, and 961 °C respectively. The controlling of AFT with pure oxy-fuel combustion eliminates the recycled flue gas (RFG) in oxy-fuel CFB combustion and flue gas recirculation section; this simplifies the power plants’ design, fabrication and its installing-operating costs. Familiarising this concept can accelerate adapting oxy-fuel combustion in CFB power plant for Carbon Capturing and Sequestration (CCS). This contribution can commence and commercialise the third generation of oxy-fuel CFB combustion with zero recycled flue gas. Finally, the concept of controlling AFT by SR (λ) is validated experimentally

Simulation Studies of Gas-Solid in the Riser of a Circulating Fluidized Bed

A numerical parametric study was performed on the influence of various riser exit geometries on the hydrodynamics of gas-solid two-phase flow in the riser of a Circulating Fluidized Bed (CFB). A Eulerian continuum formulation was applied to both phases. A two fluid framework has been used to simulate fully developed gas-solid flows in vertical riser. A two dimensional Computational Fluid Dynamics (CFD) model of gas-particle flow in the CFB has been investigated using the code FLUENT. The turbulence was modeled by a k-e turbulence model in the gas phase. The simulations were done using the geometrical configuration of a CFB test rig at the Universiti Teknologi Malaysia (UTM). The CFB riser column has 265 mm (width), 72 mm (depth) and 2.7 m height. The riser is made up of interchangeable Plexiglas columns. The computational model was used to simulate the riser over a wide range of operating and design parameters. In addition, several numerical experiments were carried out to understand the influence of riser end effects, particle size, gas solid velocity and solid volume fraction on the simulated flow characteristics. The CFD model with a k-e turbulence model for the gas phase and a fixed particle viscosity in the solids phase showed good mixing behaviour. These results were found to be useful in further development of modeling of gas solid flow in the riser

Regulation of C3 Activation by the Alternative Complement Pathway in the Mouse Retina

The purpose of this study was to examine the retinas of mice carrying hemizygous and null double deletions of Cfb-/- and Cfh-/-, and to compare these with the single knockouts of Cfb, Cfh and Cfd. Retinas were isolated from wild type (WT), Cfb-/-/Cfh-/-, Cfb-/-/Cfh+/-, Cfh-/-/Cfb+/-, Cfb-/-, Cfh-/- Cfd-/-, and Cfd+/- mice. Complement proteins were evaluated by western blotting, ELISA and immunocytochemistry, and retinal morphology was assessed using toluidine blue stained semi-thin sections. WT mice showed staining for C3 and its breakdown products in the retinal vasculature and the basal surface of the retinal pigment epithelium (RPE). Cfb-/- mice exhibited a similar C3 staining pattern to WT in the retinal vessels but a decrease in C3 and its breakdown products at the basal surface of the RPE. Deletion of both Cfb and Cfh restored C3 to levels similar to those observed in WT mice, however this reversal of phenotype was not observed in Cfh-/-/Cfb+/- or Cfb-/-/Cfh+/- mice. Loss of CFD caused an increase in C3 and a decrease in C3 breakdown products along the basal surface of the RPE. Overall the retinal morphology and retinal vasculature did not appear different across the various genotypes. We observed that C3 accumulates at the basal RPE in Cfb-/-, Cfb-/-/Cfh-/-, Cfb-/-/Cfh+/-, Cfd-/- and WT mice, but is absent in Cfh-/- and Cfh-/-/Cfb+/- mice, consistent with its consumption in the serum of mice lacking CFH when CFB is present. C3 breakdown products along the surface of the RPE were either decreased or absent when CFB, CFH or CFD was deleted or partially deleted

The accumulation of the cyanobacterial toxin, microcystin, in cherry tomato (Solanum lycopersicum) and bush bean (Phaseolus vulgaris) plants

We aimed to develop a high-sensitivity method to detect microcystin toxins in fruit tissue and to determine if irrigation with water containing toxic cyanobacteria may result in accumulation of microcystin toxins in fruit tissue and affect fruit development. In a greenhouse experiment bush beans (Phaseolus vulgaris) and tomato plants (Solanum lycopersicum) were grown in the summer under natural light and temperature between the months of September and August. Mature plants received treatments of toxic, Microcystis aeruginosa, applied twice weekly to the soil. To simulate naturally contaminated irrigation water, the M. aeruginosa were applied to plants as a suspension of intact cells. After harvesting, fruiting bodies (beans and tomatoes) were homogenized and extracted with 80% methanol (MeOH) and analyzed by ELISA for microcystins. The first extraction method tested the extraction of 0.45 g fruit tissue in 1.5 mL MeOH, buffered with PBS after 24 hr and yielded MC concentrations just above detectable limits of the ELISA. The second extraction method concentrated samples using a SpeedVac and yielded MC concentrations in range of the ELISA. The third method filtered samples from Method 2 as a preliminary investigation into matrix effects and reduced MC concentration on an average of 84%. To determine if Microcystis affected the growth of the plant’s fruit, all harvested beans and tomatoes were individually measured, weighed and photographed before processing their tissue for ELISA. The presence of cyanobacteria stimulated bean growth (t-Test P\u3c0.05), although there was no effect on the size or growth of tomatoes. Treated plants produced more fruit than the controls, although the difference was not statistically significant. The high - sensitivity method of MC extraction allows for detection of the cyanotoxins and microcystins, in the fruiting bodies of plants and an assessment of the health risk to humans and livestock

Forward-backward elliptic anisotropy correlation in parton cascade

A potential experimental probe, forward-backward elliptic anisotropy correlation ($C_{FB}$), has been proposed by Liao and Koch to distinguish the jet and true elliptic flow contribution to the measured elliptic flow ($v_2$) in relativistic heavy-ion collisions. Jet and flow fluctuation contribution to elliptic flow is investigated within the framework of a multi-phase transport model using the $C_{FB}$ probe. We found that the $C_{FB}$ correlation is remarkably different and is about two times of that proposed by Liao and Koch. It originates from the correlation between fluctuation of forward and backward elliptic flow at low transverse momentum, which is mainly due to the initial correlation between fluctuation of forward and backward eccentricity. This results in an amendment of the $C_{FB}$ by a term related to the correlation between fluctuation of forward and backward elliptic flow. Our results suggest that a suitable rapidity gap for $C_{FB}$ correlation studies should be around $\pm$ 3.5.Comment: 4 pages, 3 figure

COMPLEMENT FACTOR B IS A DETERMINANT OF BOTH METABOLIC AND CARDIOVASCULAR FEATURES OF METABOLIC SYNDROME

CFB (complement factor B) is elevated in adipose tissue and serum from patients with type 2 diabetes mellitus and cardiovascular disease, but the causal relationship to disease pathogenesis is unclear. Cfb is also elevated in adipose tissue and serum of the spontaneously hypertensive rat, a well-characterized model of metabolic syndrome. To establish the role of CFB in metabolic syndrome, we knocked out the Cfb gene in the spontaneously hypertensive rat. Cfb−/− rats showed improved glucose tolerance and insulin sensitivity, redistribution of visceral to subcutaneous fat, increased adipocyte mitochondrial respiration, and marked changes in gene expression. Cfb−/− rats also had lower blood pressure, increased ejection fraction and fractional shortening, and reduced left ventricular mass. These changes in metabolism and gene expression, in adipose tissue and left ventricle, suggest new adipose tissue-intrinsic and blood pressure-independent mechanisms for insulin resistance and cardiac hypertrophy in the spontaneously hypertensive rat. In silico analysis of the human CFB locus revealed 2 cis-regulated expression quantitative trait loci for CFB expression significantly associated with visceral fat, circulating triglycerides and hypertension in genome-wide association studies. Together, these data demonstrate a key role for CFB in the development of spontaneously hypertensive rat metabolic syndrome phenotypes and of related traits in humans and indicate the potential for CFB as a novel target for treatment of cardiometabolic disease