Level Of Oxygen Transport Research Articles

Thermochemical Recycling of Automotive Shredder Residue by Chemical-Looping Gasification Using the Generated Ash as Oxygen Carrier

Recycling of the carbon atoms from plastic waste is a crucial step in establishing a circular economy. The intense sorting required to produce easily treatable streams inevitably produces highly heterogeneous waste byproducts, which are challenging to recycle. In this paper, we propose that automotive shredder residue (ASR), which is one such heterogeneous waste, can be recycled by chemical-looping gasification (CLG), using its own ash as the oxygen-carrying bed material. We investigate two critical issues regarding the feasibility of the process: how to achieve complete conversion of the ASR in the fuel reactor and whether the heat of oxidation of the bed material is sufficient to fulfill the energy demand of the process, especially when complete conversion of ASR is achieved in the fuel reactor. This work is based on experiments conducted in the 2–4 MWth Chalmers dual fluidized bed gasifier. Assessed were the impacts on ASR conversion of four operational parameters: the bed material circulation rate; the ASR feeding rate; the levels of oxygen transport between the reactors; and the fuel reactor temperature. A heat balance for the system was established to assess the feasibility of CLG from the energy standpoint. The transport of oxygen was found to be the decisive parameter in the process, as it had the strongest impact on ASR conversion and directly affected the heat release in the air reactor. The oxygen transport level was found to be insufficient to cover the heat demand of the CLG process, indicating that strategies to increase oxygen transport are needed. However, carbon dioxide was found to be the main product of the process (on a carbon basis) and the carbon that was converted by increasing the oxygen transport formed carbon dioxide exclusively. Therefore, the viability of the CLG process for ASR recycling requires the valorization of carbon dioxide.

Using Ilmenite To Reduce the Tar Yield in a Dual Fluidized Bed Gasification System

Biomass gasification plays an important role in the emerging production of second-generation biofuels. One of the major challenges facing biomass gasification is to find simple and efficient ways to reform tar components. While the tar causes operational problems, it can be reformed to increase the chemical efficiency of the gasification process. With respect to tar reforming, catalytic materials are of special interest. Many of the materials that have been proposed as promising catalysts are metal oxide-based materials. However, metal oxides also have the ability to transport oxygen when subjected to alternating oxidizing and reducing atmospheres, similar to that which occurs in a dual fluidized bed gasification system. In this work, ilmenite was used as the catalytic material in the Chalmers 2–4 MWth dual fluidized bed gasifier to decrease the yield of tar. The ilmenite was mixed with the silica sand, which was used as the bed material, to investigate how the level of ilmenite affected chemical efficiency and tar yield. Furthermore, energy balance calculations were established to elucidate the general aspects of oxygen transport in dual fluidized bed gasification systems. The results presented in this paper reveal that adding low levels of ilmenite reduces the tar yield by ∼50%mass. However, the oxygen transport induced by ilmenite caused a reduction in the chemical efficiency of the gasifier and the heating value of the gas, compared to using 100% silica sand as the bed material. The impact of adding ilmenite was found to be dependent upon the operational conditions of the gasifier; a low fluidization velocity gave the highest reduction of the tar yield, whereas higher fluidization velocities led to increased levels of heavy components. Overall, the use of ilmenite as a catalyst for reduction of the yield of tar appears promising, provided that the level of oxygen transport can be restricted.

Oxygen transport and stability of asymmetric SrFe(Al)O 3− δ-SrAl 2O 4 composite membranes

In order to appraise a two-stage compaction procedure using pore-forming additives for the fabrication of asymmetric mixed-conducting membranes where the porous and dense layers are made of the same composition, the oxygen permeability of a series of (SrFeO 3− δ ) 0.7(SrAl 2O 4) 0.3 composite samples with varying architecture was studied at 1073–1223 K. The preparation route for the crack-free supported membranes included pressing of the starch-containing and pure dual-phase composite powders, sintering at 1623 K, and subsequent surface modification of the dense layers having the thickness of 0.12–0.15 mm. Analysis of the oxygen permeation fluxes show a significant limiting effect of oxygen diffusion through the support, where the porosity and average pore size are 20% and 2–4 μm, respectively. The overall level of oxygen transport, higher than that in the symmetric surface-activated membranes, was only achieved at 1173–1223 K for the porous layer thickness of 0.4 mm. Slow microstructural degradation due to the support sintering, evidenced by dilatometry, leads to a moderate decrease in the oxygen fluxes with time. At 1973 K, the corresponding changes were approximately 16% during 220 h. The results suggest that increased total porosity, preferential pore orientation perpendicular to the dense layer and incorporation of nano-sized catalyst particles into the pores are needed to increase the performance of asymmetric ferrite-based membranes.

Blood rheology of Antarctic fishes: viscosity adaptations at very low temperatures

Viscosity of whole blood and plasma from Antarctic fishes were compared over a temperature range of −1.5 to 5°C; human samples and water provided reference values. Blood viscosity of nototheniids was greater than that of the haemoglobinless icefish, reflecting differences in packed cell volume, being 5.27 v. 3.27 cP at 0°C for Notothenia coriiceps and Chaenocephalus aceratus, respectively. The reduction in MCHC, rather than haematocrit, in nototheniids suggests that selection pressure has not acted at the level of oxygen transport. However, icefish plasma viscosity was similar to human, but greater than that of Notothenia spp., suggesting that viscometric influences on cardiac afterload may be adaptive for the latter. Indeed, handling stress induced a significant increase in viscosity of both whole blood and plasma which may impair cardiovascular performance. Such a response was not observed in icefish, and in view of the large blood vessels it is unlikely that viscosity plays any significant role in limiting activity of this species.

Blood rheology of Antarctic fishes: viscosity adaptations at very low temperatures

Viscosity of whole blood and plasma from Antarctic fishes were compared over a temperature range of −1.5 to 5°C; human samples and water provided reference values. Blood viscosity of nototheniids was greater than that of the haemoglobinless icefish, reflecting differences in packed cell volume, being 5.27 v. 3.27 cP at 0°C for Notothenia coriiceps and Chaenocephalus aceratus, respectively. The reduction in MCHC, rather than haematocrit, in nototheniids suggests that selection pressure has not acted at the level of oxygen transport. However, icefish plasma viscosity was similar to human, but greater than that of Notothenia spp., suggesting that viscometric influences on cardiac afterload may be adaptive for the latter. Indeed, handling stress induced a significant increase in viscosity of both whole blood and plasma which may impair cardiovascular performance. Such a response was not observed in icefish, and in view of the large blood vessels it is unlikely that viscosity plays any significant role in limiting activity of this species.

5403575 Highly fluorinated, chloro-substituted organic compound-containing emulsions and methods of using them

This invention relates to compositions comprising highly fluorinated, chloro-substituted, non-cyclic organic compounds having 7 to 9 carbon atoms and to processes of using them. More particularly, this invention relates to emulsions comprising those highly fluorinated, chloro-substituted organic compounds in a sufficiently high concentration to be effective in the desired level of oxygen transport, which emulsions are capable of sterilization; have long term stability, persist for sufficiently long times in the bloodstream to deliver useful quantities of oxygen, yet be eliminated rapidly enough from the body to avoid toxicity arid retention in body parts and organs. This invention also relates to emulsions comprising non-cyclic perfluorochloroethers having 7 to 10 carbon atoms, preferably 7 to 9 carbon atoms, especially perfluoro-bis-chlorobutyl ether. These novel emulsions have various medical and oxygen transport applications, such as "artificial blood" and preserving organs.

Septic shock

Reduced cardiac output is a crucial determinant in hypovolemic, cardiogenic and obstructive types of acute circulatory failure, but cardiac output is considered less meaningful in septic shock where the primary defect is thought to be peripheral. In septic states, oxygen transport values are typically elevated, and the altered oxygen extraction (ratio of oxygen uptake over oxygen supply) limits the ability of the tissues to increase their oxygen uptake in relation to high oxygen needs. To correct tissue hypoxia, oxygen consumption should be increased to a level where oxygen uptake equals oxygen demand and lactic acidosis resolves. For a given level of oxygen demand, the best option is to improve oxygen extraction so that oxygen consumption will be higher for the same level of oxygen transport. This, however, is very difficult. Another approach can consist of further increasing oxygen transport to meet the elevated oxygen demand. Whenever possible, the metabolic needs of the tissues should be restrained.