Towards Biomass Gasification Enhanced by Structured Iron-Based Catalysts

The main drawback for the development of biomass gasification technology is tar conversion. Among the various methods for tar abatement, the use of catalysts has been proposed in the literature. Most of the works reported in the literature on catalytic systems for biomass tar conversion refers to catalysts in the form of powder; however, deactivation occurs by fast clogging with particulates deriving from biomass gasification. The integration of catalytic filter element for particle and tar removal directly integrated into the freeboard of the reactor is a new concept recently proposed and patented. In this context, this paper evaluates the possibility to integrate a structured iron-based catalytic monolith in the freeboard of a fluidized bed gasifier to enhance biomass gasification. The effectiveness of using a monolith for gas conditioning has been preliminarily verified. The limited effect on the gas production and composition seems to be related to the limited range of operating conditions explored in this work rather than to the low activity of the iron-based catalyst. Further studies to optimize the performance and to assess the possible deactivation of the catalyst due to coke deposition must be carried out.

Gas conditioning during helmet noninvasive ventilation: effect on comfort, gas exchange, inspiratory effort, transpulmonary pressure and patient–ventilator interaction

Background There is growing interest towards the use of helmet noninvasive ventilation (NIV) for the management of acute hypoxemic respiratory failure. Gas conditioning through heat and moisture exchangers (HME) or heated humidifiers (HHs) is needed during facemask NIV to provide a minimum level of humidity in the inspired gas (15 mg H2O/L). The optimal gas conditioning strategy during helmet NIV remains to be established. Methods Twenty patients with acute hypoxemic respiratory failure (PaO2/FiO2 < 300 mmHg) underwent consecutive 1-h periods of helmet NIV (PEEP 12 cmH2O, pressure support 12 cmH2O) with four humidification settings, applied in a random order: double-tube circuit with HHs and temperature set at 34 °C (HH34) and 37 °C (HH37); Y-piece circuit with HME; double-tube circuit with no humidification (NoH). Temperature and humidity of inhaled gas were measured through a capacitive hygrometer. Arterial blood gases, discomfort and dyspnea through visual analog scales (VAS), esophageal pressure swings (ΔPES) and simplified pressure–time product (PTPES), dynamic transpulmonary driving pressure (ΔPL) and asynchrony index were measured in each step. Results Median [IqR] absolute humidity, temperature and VAS discomfort were significantly lower during NoH vs. HME, HH34 and HH37: absolute humidity (mgH2O/L) 16 [12–19] vs. 28 [23–31] vs. 28 [24–31] vs. 33 [29–38], p < 0.001; temperature (°C) 29 [28–30] vs. 30 [29–31] vs. 31 [29–32] vs 32. [31–33], p < 0.001; VAS discomfort 4 [2–6] vs. 6 [2–7] vs. 7 [4–8] vs. 8 [4–10], p = 0.03. VAS discomfort increased with higher absolute humidity (p < 0.01) and temperature (p = 0.007). Higher VAS discomfort was associated with increased VAS dyspnea (p = 0.001). Arterial blood gases, respiratory rate, ΔPES, PTPES and ΔPL were similar in all conditions. Overall asynchrony index was similar in all steps, but autotriggering rate was lower during NoH and HME (p = 0.03). Conclusions During 1-h sessions of helmet NIV in patients with hypoxemic respiratory failure, a double-tube circuit with no humidification allowed adequate conditioning of inspired gas, optimized comfort and improved patient–ventilator interaction. Use of HHs or HME in this setting resulted in increased discomfort due to excessive heat and humidity in the interface, which was associated with more intense dyspnea. Trail Registration Registered on clinicaltrials.gov (NCT02875379) on August 23rd, 2016.

Rapid Gas Hydrate Formation—Evaluation of Three Reactor Concepts and Feasibility Study

Gas hydrates show great potential with regard to various technical applications, such as gas conditioning, separation and storage. Hence, there has been an increased interest in applied gas hydrate research worldwide in recent years. This paper describes the development of an energetically promising, highly attractive rapid gas hydrate production process that enables the instantaneous conditioning and storage of gases in the form of solid hydrates, as an alternative to costly established processes, such as, for example, cryogenic demethanization. In the first step of the investigations, three different reactor concepts for rapid hydrate formation were evaluated. It could be shown that coupled spraying with stirring provided the fastest hydrate formation and highest gas uptakes in the hydrate phase. In the second step, extensive experimental series were executed, using various different gas compositions on the example of synthetic natural gas mixtures containing methane, ethane and propane. Methane is eliminated from the gas phase and stored in gas hydrates. The experiments were conducted under moderate conditions (8 bar(g), 9–14 °C), using tetrahydrofuran as a thermodynamic promoter in a stoichiometric concentration of 5.56 mole%. High storage capacities, formation rates and separation efficiencies were achieved at moderate operation conditions supported by rough economic considerations, successfully showing the feasibility of this innovative concept. An adapted McCabe-Thiele diagram was created to approximately determine the necessary theoretical separation stage numbers for high purity gas separation requirements.

High-Pressure Natural Gas Pipeline in Geohazard Region of Papua New Guinea Sustains Mw7.5 Earthquake: Key Factors of Successful Outcome

ExxonMobil PNG Limited (EMPNG) operates the Papua New Guinea Liquefied Natural Gas Project (PNG LNG), an integrated LNG project comprising wellpads, gathering lines, gas conditioning plant, onshore and offshore export pipelines, liquefaction plant and marine terminal in Papua New Guinea (PNG). The PNG LNG project is a joint venture with participation by ExxonMobil, Oil Search Limited (OSL), Kumul Petroleum, Santos, JX Nippon Oil and Gas Exploration and Mineral Resources Development Company, and began production in 2014. The highlands of PNG presents a challenging physical environment, with high rainfall, steep terrain, active tectonics and seismicity, and ongoing landsliding and erosion. The PNG LNG onshore gas and condensate pipelines confront these physical challenges by having to traverse approximately 150 km of steep volcanic, mudstone and Karstic highlands along the Papuan Fold and Thrust Belt, the modern leading edge of active mountain-building, plus an additional 150 km in Karstic lowlands. During design, construction and operations of the pipelines, ExxonMobil has addressed these challenges in partnership with the engineering, construction and specialist consulting communities. On February 25th, 2018 (UTC) a Magnitude 7.5 earthquake struck the PNG highlands. The event, along with its approximately 300 aftershocks, caused widespread community impact, landsliding and damage to over 1000s of km2, and was centered directly under the highlands portion of the PNG LNG pipelines. The pipelines however, did not lose containment or pressure, and, following inspections and repairs to the PNG LNG gas conditioning plant, PNG LNG production was restored within seven weeks of the main shock. This technical paper and companion oral presentation discuss the key factors of this successful outcome, in particular the sustained condition of the gas and condensate pipelines. Contributing factors to the pipeline’s success include route selection, pipe material specification, early commitment to field studies, careful assessment of geohazards, high awareness of off-ROW community impacts, micro-routing during construction, and active geohazard management during startup and operations. The paper demonstrates that, with respect for the host community, thoughtful engineering, careful construction and ongoing surveillance, pipelines can be safely and successfully designed, constructed and operated in remote and extreme geohazardous environments.

Technical Evaluation of the Applicability of Gas-Liquid Membrane Contactors for CO2 Removal from CO2 Rich Natural Gas Streams in Offshore Rigs

This work aimed to fulfill a technical evaluation of the applicability of gas-liquid membrane contactors (GLMC) to remove CO2 from CO2 rich natural gas in offshore rigs. For this purpose, a simulation case in HYSYS 8.8 (AspenTech) was performed to remove CO2 from a natural gas stream with concentration of 40% mol CO2 using an aqueous solution of monoethanolamine (MEA) 30% w/w. GLMC unit operation is not available in HYSYS, though. Hence, it was necessary to develop a mathematical model based on log-mean of differences of CO2 fugacities in both phases. Moreover, a GLMC Unit Operation Extension (UOE) was created for GLMC units to run in the process simulator HYSYS 8.8 using its thermodynamic infrastructure. The developed GLMC unit operation extension performed accordingly to the expected behavior. For a gas feed flow rate of 5 MMNm3/d (typical from FPSO's), the calculated total GLMC mass transfer area was 1,986 m2, which requires 14 GLMC modules. Consequently, this operation showed to be a feasible option for CO2 removal in natural gas conditioning on offshore rigs. The heat ratio in the reboilers of CO2 stripping columns was found to be 167 kJ/mol, compatible with data found in the literature of CO2-MEA-H2O systems.