1,721,555 research outputs found
The design of the CASOH process pilot to test the decarbonisation of blast furnace gas using the Ca-Cu chemical loop
No full textWe present the design features of a TRL7 pilot under construction in the Arcelor Mittal´s Gas Lab site in Asturias (Spain), to demonstrate the viability of the Calcium Assisted Steel-mill Off-gas Hydrogen (CASOH) process to decarbonise Blast Furnace Gases [1,2,3]. The work is carried out within the EU C4U project (https://c4u-project.eu/, [3]). The CASOH process relies on high-temperature solid looping reactions, carried out in a number of packed-bed reactors that continuously switch between three reaction stages. In a first stage (also called CASOH), there is carbonation of CaO by capture the CO2, including the CO2 formed by the catalysed Water Gas Shift of the CO contained in the BFG. In a second reaction stage, there is oxidation of the WGS Cu catalyst with air. In a third and final stage, there is the exothermic reduction of the CuO with a fuel gas, to drive the decomposition of CaCO3 and generate a concentrated CO2 gas stream while regenerating the CaO used in the first reaction stage. The CASOH TRL7 pilot has been designed to have a single reactor (with a thermally insulated bed of functional Ca and Cu materials of 5 m height and 0.5 m inner diameter), capable to alternate between all three reaction stages. The pilot will be operated at close to atmospheric pressure within the C4U project, but has enhanced capabilities to accommodate pressure swings of up to 10 bar in the future. It can treat 300 Nm3/h of BFG (about 0.3 MWth) from the AM industrial site and generate an equivalent amount of decarbonised N2/H2 rich-gas and up to 0.7 MWth of sensitive heat at high temperature in heat removal stages. First experimental results at TRL7 are expected by the end of 2022, but successful set of results have been obtained at smaller scale (TRL3-4) with the chosen functional materials (a commercial Cu-catalyst and a commercial limestone with adequate mechanical and chemical properties) and presented in other communications at GHGT16 [4,5]
The work and preliminary results of the C4u project on advanced carbon capture for steel industries integrated in Ccus clusters
No full textThis paper provides an overview of the aims, objectives and preliminary findings of the C4U holistic interdisciplinary project, which addresses all the essential elements required for the optimal integration of CO2 capture in the iron and steel industry as part of the Carbon Capture, Utilisation and Storage (CCUS) chain. The project’s scope spans pilot-scale demonstration of two highly efficient CO2 capture technologies at TRL7 designed for optimal integration into an iron and steel plant along with detailed consideration of the safety, environmental, societal, policy and business aspects for successful incorporation of CCUS into the North Sea Port industrial cluster. The new sorbent-based CO2 capture technologies in C4U are known as DISPLACE (high temperature sorption-DISPLACEment process for CO2 recovery) and CASOH (Calcium Assisted Steel-mill Off-gas Hydrogen production). Both approaches involve high-temperature gas-solid separation processes that reduce the exergy penalty associated with CO2 capture. The progress made on the design and construction of pilot-scale CO2 capture test facilities for assessing the technologies’ performance is presented, along with results of uniquely developed mathematical models and laboratory-scale tests performed for gaining understanding of the physical and chemical phenomena underpinning the processes. The use of these results to establish the full-scale design of the technologies for deployment in an integrated steel-mill using process simulation techniques while quantifying the techno-economic and environmental performance in comparison to reference technologies (e.g. amine based CO2 capture) is also discussed. Analysis undertaken to help interface the technologies with CO2 transport and storage infrastructure is described with particular regard to requirements to meet target compositional specifications, operational safety of CO2 pipelines while also carrying impurities and mathematical tools required for the design and operation of a CCUS cluster in view of future expansion. The development of novel business models for facilitating deployment so that the long-term business case can be established through consideration of the concerns of a multitude of various stakeholders and identification of optimal scenarios for overcoming financial risks is discussed. Progress on evaluating societal readiness and public support for CCUS through just transitions in industrial clusters is also presented. The project’s work is expected to demonstrate CO2 capture from an integrated steel-mill in safe and economic CCUS value chains while establishing viable pathways to rollout of CCUS in industrial clusters
Small-scale production of hydrogen via auto-thermal reforming in an adiabatic packed bed reactor:Parametric study and reactor's optimization through response surface methodology
No full textIn this work, a two-dimensional (2-D) heterogeneous reactor model for ATR process is presented. In order to authenticate the developed reactor model outputs, literature results as well as thermodynamic findings produced by employing chemical equilibrium with applications (CEA) software were compared with the model predictions and an excellent agreement was evidenced that corroborates the model's accurate predictive capability. Response surface methodology combined with central composite design was used to investigate the significance of operational parameters on the performance of the ATR process and Parametric optimization was performed to find the optimal operating conditions. Further insights into the ATR process were obtained by studying the effect of temperature, pressure, S/C, oxygen to carbon ratio (O/C) and gas mass flow velocity (Gs) on CH4 conversion, H2 yield (wt. % of CH4) and H2 purity. It was concluded that 973 K, 1.5 bar, S/C of 3.0, O/C of 0.45 and Gs of 0.15 kg/m2s resulted in CH4 conversion and H2 purity up to 97.6% and 71.8%, respectively.</p
Dynamical Study of Fractional Model of Allelopathic Stimulatory Phytoplankton Species
No full textIn this paper, we present a fractional model of interacting phytoplankton species in which one species produces chemical which is stimulatory in nature to the other species. We study existence, uniqueness, permanence, persistence and stability of the solution. We introduce a new method to prove permanence and persistence, which may be applicable to several ecological models of fractional order. At the end we propose a discritization method and perform some numerical simulations to validate our analytical findings
Bulk-wave ultrasonic propagation imagers
No full textLaser-based ultrasound systems are described that utilize the ultrasonic bulk-wave sensing to detect the damages and flaws in the aerospace structures. These systems apply pulse-echo or through transmission methods to detect longitudinal through-the-thickness bulk-waves. These thermoelastic waves are generated using Q-switched laser and non-contact sensing is performed using a laser Doppler vibrometer (LDV). Laser-based raster scanning is performed by either two-axis translation stage for linear-scanning or galvanometer-based laser mirror scanner for angular-scanning. In all ultrasonic propagation imagers, the ultrasonic data is captured and processed in real-time and the ultrasonic propagation can be visualized during scanning. The scanning speed can go up to 1.8 kHz for two-axis linear translation stage based B-UPIs and 10 kHz for galvanometer-based laser mirror scanners. In contrast with the other available ultrasound systems, these systems have the advantage of high-speed, non-contact, real-time, and non-destructive inspection. In this paper, the description of all bulk-wave ultrasonic imagers (B-UPIs) are presented and their advantages are discussed. Experiments are performed with these system on various structures to proof the integrity of their results. The C-scan results produced from non-dispersive, through-the-thickness, bulk-wave detection show good agreement in detection of structural variances and damage location in all inspected structures. These results show that bulk-wave UPIs can be used for in-situ NDE of engineering structures
To sleep or not to sleep: understanding the social behavior of lifetime-aware networks
No full textNetwork lifetime is one of the key characteristics for evaluating wireless sensor networks (WSNs) in an application-specific way based on the availability of sensor nodes, wireless radio coverage, and wireless connectivity. Basically it shows in a resource constrained environment the consumption of every limited resource must be considered. A large number of energy efficient protocols and algorithms have been proposed in WSNs, mainly by introducing a sleep mode (SM) state to prolong the lifetime of a sensor network. The network nodes or links can be switched between working and sleep modes dynamically according to the real-time traffic situations. While there are far less critical discussions on what can be the negative effects of SMs on network lifetime in terms of hardware reliability such as failure rate. The duration of SMs tends to increase hardware lifetime, while the frequency of power state transitions tends to decrease it. In this paper, we extend the lifetime concepts in WSNs to wired network to reveal the side-effects of SMs on the hardware reliability. We have extensively studied the lifetime behavior of network links in a backbone network scenario as well as identified the sensitive social factors impacting the network lifetime. This novel research dimension is thought-provoking and opening a new conversation for researchers who are working in the areas of sustainable communications and computing to rethink and redesign the energy efficient approaches so as to address their possible side-effects on hardware reliability for the next stage of their implementation.Network lifetime is one of the key characteristics for evaluating wireless sensor networks (WSNs) in an application-specific way based on the availability of sensor nodes, wireless radio coverage, and wireless connectivity. Basically it shows in a resource constrained environment the consumption of every limited resource must be considered. A large number of energy efficient protocols and algorithms have been proposed in WSNs, mainly by introducing a sleep mode (SM) state to prolong the lifetime of a sensor network. The network nodes or links can be switched between working and sleep modes dynamically according to the real-time traffic situations. While there are far less critical discussions on what can be the negative effects of SMs on network lifetime in terms of hardware reliability such as failure rate. The duration of SMs tends to increase hardware lifetime, while the frequency of power state transitions tends to decrease it. In this paper, we extend the lifetime concepts in WSNs to wired network to reveal the side-effects of SMs on the hardware reliability. We have extensively studied the lifetime behavior of network links in a backbone network scenario as well as identified the sensitive social factors impacting the network lifetime. This novel research dimension is thought-provoking and opening a new conversation for researchers who are working in the areas of sustainable communications and computing to rethink and redesign the energy efficient approaches so as to address their possible side-effects on hardware reliability for the next stage of their implementation
Modelling of high purity H2 production via sorption enhanced chemical looping steam reforming of methane in a packed bed reactor
Full text linkSorption enhanced chemical looping steam reforming of methane (SE-CLSR) relies on the exothermicity of both a metal catalyst’s oxidation and the in situ CO2 capture by carbonation onto a solid sorbent to provide the heat demand of hydrogen (H2) production by steam reforming while generating a nearly pure H2 product. A brief thermodynamic analysis to study the main features of the SE-CLSR process is done prior to the reactor modelling work. Later, one dimensional mathematical model of SE-CLSR process in the packed bed configuration is developed using gPROMS model builder 4.1.0® under the adiabatic conditions. This model combines reduction of the NiO catalyst with the steam reforming reactions, followed by the oxidation of the Ni-based reduced catalyst. The individual models of NiO reduction, steam reforming with in situ CO2 capture on Ca-sorbent, and Ni re-oxidation are developed by using kinetic data available in literature and validated against previous published work. The model of SE-CLSR is then applied to simulate 10 alternative cycles of the fuel and air feed in the reactor. The performance of the model is studied in terms of CH4 conversion, CO2 capture efficiency, purity and yield of H2. The sensitivity of the process is studied under the various operating conditions of temperature, pressure, molar steam to carbon ratio (S/C) and mass flux of the gas phase. In this work, the operating conditions used for the production of H2 represent realistic industrial production conditions.The sensitivity analysis demonstrates that the developed model of SE-CLSR process has the flexibility to simulate a wide range of operating conditions of temperature, pressure, S/C and mass flux of the gas phase
Modelling of H₂ production in a packed bed reactor via sorption enhanced steam methane reforming process
Full text linkThe sorption enhanced steam reforming (SE-SMR) of methane over the surface of 18 wt. % Ni/ Al₂O₃ catalyst and using CaO as a CO₂-sorbent is simulated for an adiabatic packed bed reactor. The developed model accounts for all the aspects of mass and energy transfer, in both gas and solid phase along the axial direction of the reactor. The process was studied under temperature and pressure conditions used in industrial SMR operations. The simulation results were compared with equilibrium calculations and modelling data from literature. A good agreement was obtained in terms of CH₄ conversion, hydrogen yield (wt. % of CH₄ feed), purity of H₂ and CO₂ capture under the different operation conditions such as temperature, pressure, steam to carbon ratio (S/C) and gas mass flux. A pressure of 30 bar, 923 K and S/C of 3 can result in CH₄ conversion and H₂ purity up to 65% and 85% respectively compared to 24% and 49% in the conventional process
Modelling of H2 production via sorption enhanced steam methane reforming at reduced pressures for small scale applications
Full text linkThe production of H2 via sorption enhanced steam reforming (SE-SMR) of CH4 using 18 wt. % Ni/ Al2O3 catalyst and CaO as a CO2-sorbent was simulated for an adiabatic packed bed reactor at the reduced pressures typical of small and medium scale gas producers and H2 end users. To investigate the behaviour of reactor model along the axial direction, the mass, energy and momentum balance equations were incorporated in the gPROMS modelbuilder®. The effect of operating conditions such as temperature, pressure, steam to carbon ration (S/C) and gas mass flow velocity (Gs) was studied under the low-pressure conditions (2 – 7 bar). Independent equilibrium based software, chemical equilibrium with application (CEA), was used to compare the simulation results with the equilibrium data. A good agreement was obtained in terms of CH4 conversion, H2 yield (wt. % of CH4 feed), purity of H2 and CO2 capture for the lowest (Gs) representing conditions close to equilibrium under a range of operating temperatures pressures, feed steam to carbon ratio. At Gs of 3.5 kg m-2s-1, 3 bar, 923 K and S/C of 3, CH4 conversion and H2 purity were up to 89% and 86% respectively compared to 44% and 63% in the conventional reforming process
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