Evaluating the impact of feed location on the bubbling fluidized bed gasification of biomass

For fluidized bed gasifiers of biomass the selection of feeding location has been identified as a significant factor in determining gasifier performance, including carbon conversion, gas efficiency, and tar concentration in the producer gas. Over-bed feeding is a simpler arrangement where the biomass feed falls onto the surface of the fluidized bed from above. This can cause elutriation of fines without ever making contact with the bed, limiting carbon conversion or increasing tar loading in the gas. On the other hand, in-bed feeding inserts the biomass feedstock beneath the surface of the bed meaning that all the biomass particles, regardless of size, must contact the fluidized bed. In-bed feeding systems are generally more complex since the feed system must seal against the hydrostatic pressure of the bed and there may be issues with heat conduction or hot sand erosion of feed system components. This work reviews published experimental comparisons between over-bed and in-bed feeding locations, including analysis of impact of the different feeding strategies on mixing and fluidized bed hydrodynamics. The findings from the review are compared against experimental results from a pilot scale (200-250 kg/h biomass feed rate) gasification of two woody feedstocks each from an in-bed and an over-bed feed position. At similar equivalence ratios, the bed temperature was decreased with in-bed feeding relative to the over bed feeding. Although in-bed feeding appeared to have improved carbon conversion to gas, the tar concentration in the producer gas was not decreased with in-bed feeding relative to over-bed feeding

Mainstream short-cut N removal modelling: current status and perspectives

This work gives an overview of the state-of-the-art in modelling of short-cut processes for nitrogen removal in mainstream wastewater treatment and presents future perspectives for directing research efforts in line with the needs of practice. The modelling status for deammonification (i.e., anammox-based) and nitrite-shunt processes is presented with its challenges and limitations. The importance of mathematical models for considering N2O emissions in the design and operation of short-cut nitrogen removal processes is considered as well. Modelling goals and potential benefits are presented and the needs for new and more advanced approaches are identified. Overall, this contribution presents how existing and future mathematical models can accelerate successful full-scale mainstream short-cut nitrogen removal applications

Microalgae biodiesel and macroalgae bioethanol: the solar conversion challenge for industrial renewable fuels

Large-scale biofuel production from a range of biomass feedstocks (i.e., oil seeds, tallow, sugar cane, corn, etc.) is technically achievable, yet, a fundamental challenge is reducing the high costs of production. This chapter summarizes the current advances and challenges of novel biofuel technologies and feedstocks, their relationship to nonrenewable and renewable inputs, and the wider advantages and disadvantages they may be expected to produce. Present technological development in the relatively mature solar—electric industry tends to focus on cost reduction of existing technical applications and designs. Macroalgae and microalgae biofuel production systems have a biological advantage in requiring less arable land than conventional agricultural biofuels. Yet, generating efficient commercial microalgae or macroalgae biofuels will require large investment in research and development through the entire production chain. Species-specific characteristics, such as high biofuel precursor productivities and suitable cultivation and harvesting methods, are vital to the success of mass biofuel production facilities

Experimental analysis of the unit cell approach for two-phase flow dynamics in curved flow channels

Flow behavior of gas\u8211liquid mixtures in thin channels has become increasingly important as a result of miniaturization of fluid and thermal systems. The present empirical study investigates the use of the unit cell or periodic boundary approach commonly used in twophase flows. This work examines the flow patterns formed in small tube diameter (<3 mm) and curved geometry flow systems for air\u8211water mixtures at standard conditions. Liquid and gas superficial velocities were varied from 0.1 to 7.0 (approx. \ub10.01) m/s and 0.03 to 14 (approx. \ub10.2) m/s for air and water respectively to determine the flow pattern formed in three geometries and dispersed bubble, plug, slug and annular flow patterns are reported using high-frame rate videography. Flow patterns formed were plotted on the generalized two-phase flow pattern map to interpret the effect of channel size and curvature on the flow regime boundaries. Relative to a straight a channel, it is shown that a \u8216C shaped\u8217 channel that causes a directional change in the flow induces chaotic advection and increases phase interaction to enhance gas bubble or liquid slug break-up thus altering the boundaries between the dispersed bubble and plug/slug flow regimes as well as between the annular and plug/slug flow regimes.NRC publication: Ye

The Role of Neutrophils in Oncolytic Orf Virus-Mediated Cancer Immunotherapy

Neutrophils are innate leukocytes with diverse effector functions that allow them to respond to pathogens rapidly. Accumulating evidence has highlighted these cells’ complex roles in the host’s response to viral infections and tumor progression. Oncolytic virotherapy is emerging as a promising treatment modality in the armamentarium of cancer therapeutics. Oncolytic viruses preferentially kill cancer cells and stimulate tumor-associated inflammation, resulting in tumor regression. Assessing the activity of individual effector cell subsets following oncolytic virotherapy is important in identifying their contribution to antitumor immunity. In this study, we investigated the role of neutrophils in oncolytic Orf-virus-mediated immunotherapy in a murine model of pulmonary melanoma metastases. The systemic administration of the Orf virus stimulated a dramatic increase in the number of leukocytes in circulation and within the tumor microenvironment, most of which were neutrophils. Analysis of tumor-burdened lungs shortly after therapy revealed significant numbers of phenotypically immature neutrophils, with the enhanced expression of molecules affiliated with activation, migration, and cytotoxicity. Neutrophils stimulated by Orf virus therapy were directly tumoricidal through tumor necrosis factor-α-mediated effects and were required for optimal antitumor efficacy following Orf virus therapy. Taken together, these data reveal neutrophils as a crucial innate effector to consider when investigating oncolytic virotherapy

Murine Mast Cells That Are Deficient in IFNAR-Signaling Respond to Viral Infection by Producing a Large Amount of Inflammatory Cytokines, a Low Level of Reactive Oxygen Species, and a High Rate of Cell Death

Mat cells (MCs) are located in the skin and mucous membranes at points where the body meets the environment. When activated, MCs release inflammatory cytokines, which help the immune system to fight viruses. MCs produce, and have receptors for interferons (IFNs), which belong to a family of cytokines recognized for their antiviral properties. Previously, we reported that MCs produced proinflammatory cytokines in response to a recombinant vesicular stomatitis virus (rVSVΔm51) and that IFNAR signaling was required to down-modulate these responses. Here, we have demonstrated that UV-irradiated rVSVΔm51 did not cause any inflammatory cytokines in either in vitro cultured mouse IFNAR-intact (IFNAR+/+), or in IFNAR-knockout (IFNAR−/−) MCs. However, the non-irradiated virus was able to replicate more effectively in IFNAR−/− MCs and produced a higher level of inflammatory cytokines compared with the IFNAR+/+ MCs. Interestingly, MCs lacking IFNAR expression displayed reduced levels of reactive oxygen species (ROS) compared with IFNAR+/+ MCs. Additionally, upon the viral infection, these IFNAR−/− MCs were found to coexist with many dying cells within the cell population. Based on our findings, IFNAR-intact MCs exhibit a lower rate of rVSVΔm51 infectivity and lower levels of cytokines while demonstrating higher levels of ROS. This suggests that MCs with intact IFNAR signaling may survive viral infections by producing cell-protective ROS mechanisms and are less likely to die than IFNAR−/− cells