Performance of The Decarboxylation Index To Predict CO2 Removal And Mechanical Ventilation Reduction Under VV-ECMO Or High-Flow ECCO2R

Background: Optimal decarboxylation dose under extracorporeal respiratory support to ensure sufficient reduction of mechanical ventilation stress remains unclear and understudied. The aim of this study was to assess the interdependence of blood flow (BF) and gas flow (GF) in predicting CO2 removal and mechanical ventilation reduction (MVR) under extracorporeal respiratory support. Methods: All patients who benefited from veno-venous ECMO (HLS-maquet 7.0, 1.8 m²) and high-flow ECCO2R (HLS-maquet 5.0, 1.3 m²) in our intensive care unit over a period of 18 months were included. CO2 removal was calculated from inlet/outlet blood gases performed in clinical practice during the first 7 days of oxygenator use. The relationship between the BF × GF product and CO2 removal or MVR was studied using linear regression models. Results: Eighteen patients were analysed, corresponding to 24 oxygenators and 261 datasets. CO2 removal was 393 mL/min (IQR, 310–526 mL/min) for 1.8 m2 oxygenators and 179 mL/min (IQR, 165–235 mL/min) for 1.3 m2 oxygenators. The decarboxylation index was associated linearly with CO2 removal (R2 = 0.62 and R2 = 0.77 for the two oxygenators, respectively) and MVR (R2 = 0.72 and R2 = 0.62, respectively). Values in the range 20−30L2/min2 were associated with an MVR ratio between 38% and 58% for 1.8 m2 oxygenators, and between 37% and 55% for 1.3 m2 oxygenators. Conclusion: The decarboxylation index is a simple parameter to predict CO2 removal and MVR under extracorporeal respiratory support. A BF of 2 L2/min2 or more may be necessary to obtain a significant reduction of mechanical convection.Trial Registration: Being a retrospective study, no trial registration was made.

Comparison of CO2 Separation Efficiency from Flue Gases Based on Commonly Used Methods and Materials

The comparison study of CO2 removal efficiency from flue gases at low pressures and temperatures is presented, based on commonly used methods and materials. Our own experimental results were compared and analyzed for different methods of CO2 removal from flue gases: absorption in a packed column, adsorption in a packed column and membrane separation on polymeric and ceramic membranes, as well as on the developed supported ionic liquid membranes (SILMs). The efficiency and competitiveness comparison of the investigated methods showed that SILMs obtained by coating of the polydimethylsiloxane (PDMS) membrane with 1-ethyl-3-methylimidazolium acetate ([Emim][Ac]) exhibit a high ideal CO2/N2 selectivity of 152, permeability of 2400 barrer and long term stability. Inexpensive and selective SILMs were prepared applying commercial membranes. Under similar experimental conditions, the absorption in aqueous Monoethanolamine (MEA) solutions is much faster than in ionic liquids (ILs), but gas and liquid flow rates in packed column sprayed with IL are limited due to the much higher viscosity and lower diffusion coefficient of IL. For CO2 adsorption on activated carbons impregnated with amine or IL, only a small improvement in the adsorption properties was achieved. The experimental research was compared with the literature data to find a feasible solution based on commercially available methods and materials.

Low CO2 Levels Are Detrimental for In Vitro Plantlets through Disturbance of Photosynthetic Functionality and Accumulation of Reactive Oxygen Species

Photosynthesis of plantlets in tissue culture containers is not considered important, compared to photosynthesis of ex vitro plants, due to the exogenous source of carbohydrates present in tissue culture media. However, CO2 starvation can generate a burst of reactive oxygen species (ROS). We examined this phenomenon in tissue culture, since CO2 levels may become very low during the light period. The research was carried out with lily scales, regenerating adventitious bulblets, and with Arabidopsis seedlings. CO2 starvation was achieved by placing a small vial of concentrated KOH solution in the culture container. CO2 removal reduced the growth of regenerated lily bulblets by 33% or 23%, with or without sucrose in the medium, respectively. In Arabidopsis seedlings, CO2 removal decreased growth by 50% or 78% in the presence or absence of sucrose in the medium, respectively. Therefore, the addition of sucrose as a replacement for photosynthesis resulted in only partial recovery of growth. Staining with nitroblue tetrazolium (NBT) showed little to no ROS in ex vitro growing seedlings, while abundant ROS were detected in seedlings grown under in vitro CO2 starvation. Seedlings grown under normal tissue culture conditions (no CO2 withdrawal) showed low levels of ROS. In lily tissue culture, CO2 starvation decreased the maximum quantum efficiency of photosystem II (Fv/Fm) from 0.69 to 0.60, and in Arabidopsis from 0.76 to 0.62. Fv/Fm of ex vitro lily and Arabidopsis seedlings was 0.77 and 0.79, respectively. This is indicative of a disturbance in photosynthesis functionality and the occurrence of in vitro stress under reduced CO2 concentrations. We conclude that poor growth, in the absence of CO2, was partly due to strongly reduced photosynthesis, while the detrimental effects were most likely due to a burst of ROS.

Optimized CO2 Capture Solutions for Carbon Free Hydrogen Production with Development of New Demixing Solvent Technology DMX™

CO2 capture & storage is foreseen as a necessity to limit global warming, as indicated by the recent reports from International Energy Agency. Major initiatives have to be initiated in a near future with concrete actions to get efficient results in limiting global warming. Based on its decades of experience in gas sweetening AXENS has developed an expertise in CO2 removal technologies. While conventional amine based processes can be used for some CO2 capture applications like for instance the treatment of process gas streams under pressure, other applications for low pressure gas streams like flue gases will require innovative advanced solutions. AXENS has studied various options for the removal of CO2 in SMR based hydrogen schemes, including the treatment of the process gas or the treatment of the flue gases from the SMR furnace, evaluating the respective merits of those options. For the treatment of the flue gases a new technology developed by IFPEN and AXENS based on a second generation amine solvent is considered : DMX™ DMX™ process, is foreseen as a key contributor for the removal of CO2 from all kind of low pressure gas streams. This process allows drastic reduction of CO2 capture cost in comparison to more conventional solvent such as MEA and others available solvents. The specific features of this solvent allows significant reduction of the heat requirements for the regeneration of the solvent. It also allows regenerating the solvent directly under pressure up to 6 bara, reducing the costs for downstream CO2 compression Preliminary techno-economic studies show significant advantage of DMX™ technology relatively to MEA : up to 30 % reduction in OPEX can be obtained for lower or similar CAPEX, depending on the condition. This process has been developed at the lab scale and is now going to be demonstrated in an industrial pilot unit installed in ArcelorMittal's steel mill plant in Dunkirk (France). This demonstration benefits from the support of EU's H2020 programme, under 3D project.

Optimizing Location of CO2 Recovery Units

In line with ADNOC Sustainability policy, reduction of GHG emissions, AGP has initiated projects for recovery of CO2 from existing plants. The extracted CO2 is planned to be used for Enhanced Oil Recovery. The current paper highlights method used for evaluation of various location and technology options for implementation of the new CO2 recovery units, considering existing plants flow schemes along with their interfaces and associated challenges. Key Performance Indicators (KPIs) were identified based on Inherent Safety, Economics, Technology Maturity, Product Quality, Operability / Flexibility, Constructability. Identified options were further developed and subsequently evaluated based on preliminary economic analysis and available technical information. Accordingly, weighted scores of the KPIs developed for option selection. Major criteria used for ranking were unit cost of CO2 product, adherence to required H2S and COS specifications, technology maturity and deployment in industry.For one location, the options considered included installation of new Acid Gas Removal Unit (AGRU) upstream of existing AGRU, revamp of existing Acid Gas Enrichment Unit (AGEU), new AGEU, and direct feed of Acid gas to new CO2 recovery unit to supplement falling upstream reservoir profile.For another location, the options included new CO2 recovery plant upstream of existing Sulphur Recovery Unit (SRU) or downstream of existing Tail Gas Treatment Unit (TGTU), compression of TGTU gases upstream of proposed CO2 recovery unit, installation of new unit downstream of existing incinerators, combination of CO2 recovery units of both plants, were also assessed.In addition, new CO2 Dehydration and Compression units considered to meet CO2 product specifications and B/L requirements. Based on project requirements, physical methods of CO2 removal like membranes and molecular sieves deemed unsuitable. Further to discussions with various licensors, emphasis remained on chemical and physical solvent technologies. Based on assessment, solvent swap for AGEU (upstream of existing SRUs) with reduced lean solvent temperature at one location, solvent swap in TGTU followed by a new polishing unit at another location combined with common high pressure compression facility, was selected for engineering development.

Colonic Oxygen Microbubbles Augment Systemic Oxygenation and CO2 Removal in a Porcine Smoke Inhalation Model of Severe Hypoxia

Inhalation injury can lead to pulmonary complications resulting in the development of respiratory distress and severe hypoxia. Respiratory distress is one of the major causes of death in critically ill patients with a reported mortality rate of up to 45%. The present study focuses on the effect of oxygen microbubble (OMB) infusion via the colon in a porcine model of smoke inhalation-induced lung injury. Juvenile female Duroc pigs (n=6 colonic OMB, n=6 no treatment) ranging from 39-51 kg in weight were exposed to smoke under general anesthesia for 2 h. Animals developed severe hypoxia 48 h after smoke inhalation as reflected by reduction in SpO2 to 66.3 % +/- 13.1% and PaO2 to 45.3 +/- 7.6 mmHg, as well as bilateral diffuse infiltrates demonstrated on chest x-ray. Colonic OMB infusion (75 - 100 mL/kg dose) resulted in significant improvements in systemic oxygenation as demonstrated by an increase in PaO2 of 13.2 +/- 4.7 mmHg and SpO2 of 15.2% +/- 10.0% out to 2.5 h, compared to no-treatment control animals that experienced a decline in PaO2 of 8.2 +/- 7.9 mmHg and SpO2 of 12.9% +/- 18.7% over the same timeframe. Likewise, colonic OMB decreased PaCO2 and PmvCO2 by 19.7 +/- 7.6 mmHg and 7.6 +/- 6.7 mmHg, respectively, compared to controls that experienced increases in PaCO2 and PmvCO2 of 17.9 +/- 11.7 mmHg and 18.3 +/- 11.2 mmHg. We conclude that colonic OMB therapy has potential to treat patients experiencing severe hypoxemic respiratory failure.

Impact of CCUS Impurities on Dense Phase CO2 Pipeline Surface Engineering Design

Numerous CO2 injection pipeline applications have been developed and implemented in the past decades in the UAE and all around the globe. Transporting the CO2 in dense phase, rather than in gas or liquid phases, is well recognized of being techno-economically attractive with respect to its major CAPEX benefits of optimized pipeline material of construction; which is driven by the high water solubility in dense phase CO2 as well as the optimized pipeline size which is greatly influenced by the density and viscosity characteristics of supercritical/dense phase CO2. In light of the active deployment of dense phase CO2 injection EOR pipeline transportation across the various existing and future CO2 capture facilities across the UAE, ADNOC onshore technical expertise team has been conducting intensive research analysis on the unique thermodynamic aspects of dense phase CO2 pipeline systems. The focus was directed towards understanding the transient characteristics, which directly influence crucial design strategies including and not limited to CO2 purity specifications, CO2 pipeline pressure and temperature operating envelopes as well as the developed operating philosophy which involves start-up, shutdown and depressurization. While optimizing the economics of the carbon capture units (CCUS) is a pivotal strategy mandating rationalizing the dictated purity level of the captured CO2 and valorizing the projects. However, such thrifty initiatives to moderate the costs of the selected CO2 removal technologies can lead to underlying cascading effects of the lower purity recovered CO2 on systems design and its operation. As part of the nation's strategic objective to reduce carbon footprint, CO2 has been recovered for EOR re-injection applications. Relaxing the purity specification met by the CO2 capture units can positively improve the cost of the recovery plant while may potentially have adverse impacts on CO2 pipeline integrity. This paper provides a comprehensive analysis of the impact of the CO2 purity specification on the flow assurance safety performance of dense phase CO2 pipeline. It is worth highlighting that the design of CO2 systems is challenged by the paucity of the available reference design guidelines since domain of CO2 itself is still evolving under an active area of research. Although some previous publications have demonstrated the latent underlying effects of imputiries such as (N2, H2, SO2, NO2, CH4, C2H6, and Argon) on the physical and thermodynamic behavior of CO2 systems, however, this was supported by literature experimental modelling without transient analysis. In this paper, the behavior of varying CO2 purity levels on the design and operational aspects of CO2 pipeline is substantiated and both steady state and transient flow assurance modelling are presented. Gauging the system's design integrity cannot be solely assured from the perspective of steady state behavior and hence this paper's findings provide additional information to that previously published with the detailed modelling applied for varying purity scenarios of captured CO2 streams employed in EOR applications across the UAE. The findings of the analysis are benchmarked against plausible worldwide CO2 compositions with a wide range of impurity levels with further in depth demonstration of the transient effects which are usually absent in the available literature.