1,426 research outputs found
Integrating IT-SOFC and gasification combined cycle with methanation reactor and hydrogen firing for near zero-emission power generation from coal
Full text linkAbstractApplication of Solid Oxide Fuel Cells (SOFC) in gasification-based power plants would represent a turning point in the power generation sector, allowing to considerably increase the electric efficiency of coal-fired power stations while reducing CO2 and other pollutant emissions. The aim of this paper is the thermodynamic assessment of a SOFC-based IGFC plant with methanation reactor, hydrogen post-firing and CO2 capture by physical absorption. The configuration proposed allows to obtain a very high net efficiency (51.6%), overcoming the main limits of configurations assessed in previous works
Preliminary assessment of IT-SOFC based integrated coal gasification fuel cell power plants
No full textEFC09-1711
SOFC-based hybrid cycle integrated with a coal gasification plant
No full textApplication of large scale high temperature fuel cells on syngas fuel produced from coal would be a turning point in the power generation sector, dramatically improving the efficiency and the environmental performance of coal-fired power plants. The purpose of this study is the assessment of a system constituted by a SOFC-based hybrid cycle integrated with a coal gasification process. In this system, syngas produced in a high efficiency, dry feed, oxygen blown, entrained flow Shell gasifier is cooled, depurated from particulate and sulfur compounds and reheated; the clean syngas feeds a pressurized SOFC together with high pressure air generated by the compressor of a gas turbine. After combustion of unconverted syngas, fuel cell exhausts are expanded and cooled, providing heat to a bottoming steam cycle for an efficient energy recovery. A high integration between gasification and power islands is necessary in order to obtain an elevated efficiency: the heat recovery system from syngas cooling is carefully arranged to provide thermal power for clean syngas reheating, air preheating and steam generation.
The paper presents a preliminary analysis of literature results and a discussion of the thermodynamic implications arising from the use of different primary fuels in a fuel cell-gas turbine cycle. Then the work presents a detailed thermodynamic analysis of the proposed IGFC layout, assessing the effect of SOFC operating pressure on power balance and net plant efficiency. A sensitivity analysis on the variation of fuel and air utilization in the fuel cell is also performed. Results show that the present innovative SOFC-based power system may achieve an efficiency gain of 7-11 percentage points, with respect to an advanced IGCC based on state of the art technology
Conversion of glycerol to acrylic acid:a review of strategies, recent developments and prospects
Full text linkAcrylic acid is an essential chemical and a vital intermediate used in the production of various commodities and industrial chemicals. However, continued reliance on petroleum-based feedstocks for the production of acrylic acid is considered unsustainable and even counterproductive to the goal of achieving net zero carbon emissions. Glycerol waste generated from biodiesel production via transesterification processes has been identified as a viable alternative feedstock. However, commercial-scale adoption is yet to be realised due to inherent challenges associated with the conversion of glycerol to acrylic acid. Herein, we review the latest strategies, challenges and prospects for the utilisation of waste glycerol as a feedstock for the production of acrylic acid. Biochemical, electrochemical, photochemical, electrocatalytic and thermocatalytic conversion routes are discussed to provide insights into recent developments made in the field. Sustainable pathways that can be potentially implemented to transform readily available waste glycerol to acrylic acid at minimal costs are also considered. Biochemical conversion routes are the most promising from an environmental perspective as they have minimal energy requirements and low global warming potentials. However, higher acrylic acid yields have been reported from thermocatalytic conversion routes.</p
Mono-dimensional and two-dimensional models for chemical looping reforming with packed bed reactors and validation under real process conditions
No full textChemical looping reforming (CLR) is an emerging hydrogen/syngas production technology, integrated with CO2 capture. Packed bed reactors are widely used in the hydrogen production industry as they are preferred for high pressure operation and the mathematical modelling describing their operation is very important for their design. In this study, a one-dimensional (1-D) and a two-dimensional (2-D) model have been developed to describe the dynamic operation of chemical looping reforming processes in packed bed reactors (CLR-PB). The reactor under study (L: 400 mm ID: 35 mm) contains an axially placed thermowell (OD: 6.35 mm) to monitor the temperature across the reactor bed at 6 points and 440 g of NiO/CaAl2O4 oxygen carrier (OC). Both models have been validated presenting very good agreement with the experimental results. The comparison between modelling and experimental results has been carried out in terms of thermowell temperature and the gas composition breakthroughs, with the 2-D model capturing the thermowell temperature recordings with high accuracy, while the 1-D model delivered results that underestimated it by 2.5%. Nonetheless, the predicted average bed temperature presented a difference limited to 1% lower estimation of the 1-D to the 2-D model. The temperature difference between the bed and the thermowell has achieved a value of >180 °C thus resulting also problematic in terms of safe operation if not properly considered. with temperatures during oxidation being higher even by 181 °C inside the bed, emphasizing the importance of the model in the proper design and safe operation of the reactor. The 1-D model, due to the significantly lower computation time (∼21 times faster than 2-D), has been selected to be tested against a range of operating conditions for oxidation (500–600 °C, 1–5 bar, 10–40 NLPM, 10–20% O2), reduction (600–900 °C, 1–5 bar) with H2, syngas and CH4-rich reducing agents and dry reforming (700–900 °C, 1–5 bar), delivering results with good agreement especially under high temperature conditions where solid conversion is high and under conditions which resemble the expected industrial ones
Experimental assessment of reverse water gas shift integrated with chemical looping for low-carbon fuels
No full textChemical looping integrated with reverse water gas (CL-RWGS) shift is presented in this study using Cu-based oxygen carrier (OC) supported on Al2O3 has been used to convert the CO2 and H2 mixture stream into a syngas stream with a tailored H2 to CO ratio and relevant conditions. The results demonstrated consistent breakthrough curves during redox cycles, confirming the chemical stability of the material. In 10 consecutive cycles at 600 °C and 1 bar, bed temperatures increased by 184 °C and 132 °C across the bed during oxidation and reduction stages respectively. The cooling effects during RWGS showed a decline in solid temperatures demonstrating the effectiveness of the heat removal strategy while attaining a CO2-to-CO conversion close >48%. The outlet gas maintains a H2/CO ratio above 2, confirming the material's dual role as OC and catalyst. During complete CL-RWGS cycles, varying temperature from 500 °C to 600 °C at a constant H2/CO2 molar ratio (1.3) and pressure (1 bar) reduces the H2/CO molar ratio from 3.14 to 2.35, respectively with a remarkable continuous CO2-to-CO conversion > 40%. The decrease in H2/CO molar ratio with the increase in temperature is consistent with the expected results of equilibrium limited conditions. Additionally, in CL-RWGS cycles, pressure insignificantly affects product molar composition. The study showed the capability of Cu material in converting CO2 into syngas through the CL-RWGS technique.</p
Carbon-neutral and carbon-negative chemical looping processes using glycerol and methane as feedstock
No full textCarbon-negative and neutral methods to produce H2 and other syngas-derived chemicals are tested and demonstrated in this study through chemical looping reforming of methane or glycerol. A chemical looping reactor provides the heat required to reform the glycerol or methane while having inherent CO2 capture. This is achieved using dynamically operated packed beds. If the glycerol or methane is from a biological source this gives the system the potential for negative emissions. To evaluate the potential of this system, 500 g packed bed of oxygen carriers were cyclically reduced, oxidized, and used to carry out reforming experiments. The reforming process was tested at various pressure (1 – 9 bar) and temperature (600 – 900 °C). These conditions were tested at this scale for the first time. Complete conversion of glycerol is achievable with only small quantities of CH4 slip. The maximum H2 production was achieved at 1 bar and 700 °C producing a H2/CO ratio of 10, this lowered to 9 when the temperature was increased to 900 °C. Adding CO2 to the feed stream along with H2O allows for a H2/CO ratio suitable for the Fischer Tropsch (FT) synthesis. Chemical looping reforming of CH4 with steam was successfully demonstrated in a lab reactor setup at 1 and 5 bar for multiple cycles with CH4 conversion > 99% and controlled heat losses. The temperature and concentration profiles provided identical results for consecutive cycles verifying the continuity and the feasibility of the process
First person – Vincenzo Torraca
Full text linkFirst Person is a series of interviews with the first authors of a selection of papers published in Disease Models & Mechanisms, helping researchers promote themselves alongside their papers. Vincenzo Torraca is first author on ‘ Transcriptional profiling of zebrafish identifies host factors controlling susceptibility toShigella flexneri’, published in DMM. Vincenzo conducted the research described in this article while he was a Marie Skłodowska-Curie Postdoctoral Fellow at Imperial College London, UK and an ISSF (Institutional Strategic Support Fund)-Wellcome Fellow at the London School of Hygiene and Tropical Medicine, UK, where most of the work was carried out in Prof. Serge Mostowy's lab. He has just started his own group at King's College London, investigating host-pathogen interactions and antimicrobial resistance for globally relevant bacterial pathogens, such as Shigella and E. coli, using zebrafish as an in vivo model
Africa II
No full textThis map appears in another example of the several translations of Ptolemy's Geography. This one, in Latin, was a translation directly from the Greek done by Pirckheimer and revised by Giuseppe Moleti. Stevens (pg. 51) notes that the maps in this version are identical to the maps in the Italian 1561 edition, also published by Vincenzo Valgrisi
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