Conventional SMR Research Articles

Novel integrated system for power, hydrogen, and ammonia production using direct oxy-combustion sCO2 power cycle with automatic CO2 capture, water electrolyzer, and Haber-Bosch process

Renewable energy-based multigeneration systems for power, hydrogen, and ammonia production suffer from intermittency issues and high production costs. On the other hand, conventional fossil-fuel-based systems yield high levels of CO2 emissions. Thus, to eliminate the intermittency issue with low production costs and near zero CO2 emissions, a novel integrated, efficient, compact, and interactive system for power, hydrogen (H2), and ammonia (NH3) production is developed and investigated in this study. A direct oxy-combustion supercritical carbon dioxide (DOC-sCO2) power plant is integrated with a water electrolyzer (WE) and Haber-Bosch process (HBP) system for the cogeneration of power, H2, and NH3, respectively. The power consumption of the air separation unit (ASU) of the DOC-sCO2 cycle is significantly reduced by the utilization of the oxygen produced from the WE system. Moreover, the cost of ammonia production is minimized by the internal utilization of the nitrogen gas produced by the ASU. Furthermore, the feedwater of the WE system is supplied internally from the DOC-sCO2 power block. In addition, the CO2 emissions of the system are captured to realize near-zero emissions to the ambiance. Based on these features, thorough energy, exergy, economic, and environmental (4E) analyses were performed to evaluate the performance of the proposed system. The obtained results showed an impressive levelized cost of electricity of 3.72¢/kWh, levelized cost of hydrogen of 1.162$/kgH2, and ammonia of 0.197$/kgNH3 at an overall energy and exergy efficiencies of 44.09 %, and 63.6 %, respectively. The system has no emissions of nitrogen oxides (NOx) and reduces the CO2 emissions of the H2 production by 49.6 % and of the NH3 production by 48.8 % compared to the conventional gasification, SMR, and HBP systems, respectively. This research work also provides insights into wet versus dry cooling, part load operation, and the advantages over renewable-based systems in terms of stability, reliability, and economic feasibility.

Recent Insights into the Production of Syngas and Hydrogen Using Chemical Looping-Steam Reforming (CL-SR)

Chemical looping-steam reforming (CL-SR) is a prospective technology for the simultaneous production of syngas and hydrogen (H2). The quality of syngas and hydrogen (H2) obtained from CL-SR process has garnered the interest of the scientific society. A recyclable oxygen storage material (oxygen carrier) is reacted through an alternating cycle of fuel (reduction step) and steam (oxidation step) at higher temperatures. Oxygen carrier (OC) plays a vital role in directing the path of the reaction in the CL-SR process. Hence, developing and selecting a proper OC is crucial. The current study intends to address recent breakthroughs in the development and performance of OCs subjected to different reacting fuel species such as methane (CL-SMR), CO2 (CL-HG), and liquid fuels. The performance of various classes of OCs such as metal oxide, mixed metal oxides, and perovskites toward conversion and lattice oxygen selectivity is investigated. The thermodynamic study and constraints related to the performance of OCs in CL-SR are discussed along with the economic evaluation of the CL-SR process and the conventional SMR process. Further, the theoretical approaches involved in determining the kinetics of the CL-SR process and kinetic models developed by the researchers are reviewed. Finally, the scientific barriers and the suggestions for optimized operation of the CL-SR process are listed.

Sustainable hydrogen manufacturing via renewable-integrated intensified process for refueling stations

The widescale consumer adoption of hydrogen fuel cell electric vehicles (HFCEVs) is currently hindered by the high cost of small-scale hydrogen generation and the lack of extensive hydrogen refueling infrastructure. Natural gas-based hydrogen is cheaper when produced in large volumes but is also associated with high CO2 emissions. To counter these challenges, we propose a hybrid approach where both natural gas and renewables are integrated in a synergistic manner using a dynamic process intensification technology that can be deployed on-site for meeting local demands of refueling stations. The technology is based on sorption enhanced steam methane reforming (SE-SMR) that utilizes a combination of reaction with in-situCO2 adsorption for enhancing process modularity, productivity and efficiency thereby outperforming conventional SMR at small scale. We develop a mixed integer linear programming (MILP)-based optimization framework for simultaneous design and scheduling of the SE-SMR process. The simultaneous optimization provides a synergistic combination whereby the renewables allow sustainable hydrogen manufacturing and the dynamic SE-SMR allows optimal use of the intermittency of the renewables. The U.S. nationwide analysis indicates that for futuristic renewable prices and a hydrogen production capacity of 2 ton/day, hydrogen can be produced at 50% less cost compared to the current cost of small-scale hydrogen generation. The city-wise analysis with varying hydrogen demand shows that even with just 5% HFCEV market penetration level, hydrogen production cost less than $3/kg can be obtained at small scales across the United States with even cheaper hydrogen for large cities.

FluidSMR: Adaptive Management for Hybrid SMR Drives

Hybrid Shingled Magnetic Recording (H-SMR) drives are the most recently developed SMR drives, which allow dynamic conversion of the recording format between Conventional Magnetic Recording (CMR) and SMR on a single disk drive. We identify the unique opportunities of H-SMR drives to manage the tradeoffs between performance and capacity, including the possibility of adjusting the SMR area capacity based on storage usage and the flexibility of dynamic data swapping between the CMR area and SMR area. We design and implement FluidSMR, an adaptive management scheme for hybrid SMR Drives, to fully utilize H-SMR drives under different workloads and capacity usages. FluidSMR has a two-phase allocation scheme to support a growing usage of the H-SMR drive. The scheme can intelligently determine the sizes of the CMR and the SMR space in an H-SMR drive based on the dynamic changing of workloads. Moreover, FluidSMR uses a cache in the CMR region, managed by a proposed loop-back log policy, to reduce the overhead of updates to the SMR region. Evaluations using enterprise traces demonstrate that FluidSMR outperforms baseline schemes in various workloads by decreasing the average I/O latency and effectively reducing/controlling the performance impact of the format conversion between CMR and SMR.

Modeling of sorption enhanced steam methane reforming in an adiabatic packed bed reactor using various CO2 sorbents

A 1-D heterogeneous model of sorption-enhanced steam methane reforming (SE-SMR) process in a packed bed reactor consisting of nickel catalyst well mixed with CO2 sorbent particles is investigated for three types of common sorbents. The performance of SE-SMR process is studied under low medium pressure conditions (3 – 11 bar) to find the optimum operating conditions. Optimal CaO sorption corresponding to 82% CH4 conversion and 85% H2 purity is found at 900 K, 3 bar, 3.5 kgm−2s−1 and S/C of 3.0. In contrast, lithium zirconate (LZC) and hydrotalcite (HTC) sorbents exhibited best sorptions under the operating conditions of 773 K, 5 bar and S/C of 3 with CH4 conversion of 91.3% and 55.2%, and H2 purity of 94.1% and 77.8% respectively. In these conditions, the CH4 conversion increased by 114%, 111% and 67% compared to the conventional SMR for the processes enhanced by HTC, LZC and CaO sorption respectively.

Technoeconomic analysis for hydrogen and carbon Co-Production via catalytic pyrolysis of methane

Catalytic Methane Pyrolysis (CMP) is an innovative method to convert gaseous methane into valuable H2 and carbon products. The catalytic approach to methane pyrolysis has the potential to decrease the required operating temperature for methane decomposition from >1000 °C to under 700 °C. In this work, a novel inexpensive catalyst is discussed that displays low operating temperatures, while still maintaining high reactivity and long proven lifetimes. The kinetics associated with the catalyst's performance are modeled and a correlation was developed for use with practical simulation tools. A techno-economic assessment was conducted applying experimentally determined kinetics for the CMP reaction with the specific catalyst. Two process concepts that utilize CMP using the novel catalyst are presented in this work. Optimizations were considered in these processes and the CO2 emissions and cost of hydrogen production of the two optimized cases, CMP with H2 combustion (CMP-H2) and CMP with CH4 Combustion (CMP-CH4), are compared to that of the current industrial standard for hydrogen production, Steam Methane Reforming with carbon capture and sequestration (SMR-CCS). Both of the proposed concepts convert methane into gaseous hydrogen and valuable carbon products, graphitic carbon to carbon Nano fibers. The carbon price was treated as a variable to determine the sensitivity of hydrogen production cost to the carbon price. The analysis indicates that cost of hydrogen production is highly dependent on the recovery and sale of carbon byproducts. Based on Aspen modeling of these two concepts for large scale hydrogen production (216 tons/day), the cost of hydrogen production, without considering carbon sales, was estimated to be $<3.25/kg, assuming a natural gas price of $7/MMBTU and conservative catalyst cost of $8/kg. Assuming 100% recovery of carbon, the price can be reduced to $0/kg by selling the carbon at <$1/kg. A market assessment suggests that values of graphitic carbon and carbon fibers range from ~$10/kg and ~$25–113/kg, respectively. The cost of H2 production via conventional SMR is ~$2.2/kg when accounting for the cost of CO2 sequestration. The proposed processes produce a maximum of 0–2 kg CO2/kg H2 in contrast to the 10 kg CO2/kg H2 produced via conventional SMR-CCS. The process displays an enormous potential for competitive economics accompanied by reduced greenhouse gas emissions.

A study of single sided mucoperichondrial resection versus conventional technique in submucosal resection

Nasal septal deviation is a condition which is frequently encountered in the general population. Surgical correction of this problem has been the mainstay of treatment for over a century.This study is to compare SMR with Single sided mucoperichondral resection. This new technique in Septal Surgery is found without complication whereas complications were noted in SMR.The study to compare the Single sided mucoperichondrial resection versus conventional SMR was carried out in the Department of Otorhinolaryngology at AJ Institute of Medical Sciences and Research Centre, Mangalore, Karnataka during the period from 1 October 2018 to 31 September 2019.A total of 20 cases with symptomatic DNS were included in the study, after randomization 10 cases underwent conventional SMR and 10 cases Single sided mucoperichondrial resection.Among 10 patients who underwent conventional SMR, Septal hematoma and septal perforation were the most common complications. None of the patients who underwent Single sided mucoperichondrial resection had any complications.In conventional SMR, retention of both mucoperichondrial flaps results in many recognized post op complications. In Single sided mucoperichondrial resection, no complications were seen in comparison.

Temperature dependence of spin Hall magnetoresistance across the Néel temperature of CoO

Spin Hall magnetoresistance has been used to probe magnetic moments in magnetic insulator/heavy metal thin films. Here we explore the magnetic field-dependent magnetoresistance and the temperature-dependent magnetoresistance in a Pt/CoO/Pt trilayer near the Néel temperature of CoO. The obtained magnetoresistance in an antiferromagnetic phase can be interpreted as SMR whereas the results in a paramagnetic one suggest the additional mechanism other than the conventional SMR.

GRAMS: A general framework describing adsorption, reaction and sorption-enhanced reaction processes

We present a generalized reaction-adsorption modeling and simulation (GRAMS) framework that captures both reaction and adsorption dynamics in columns with solid catalysts, porous adsorbents or both. It is based on a 1-dimensional, pseudo-homogeneous, non-isothermal, non-adiabatic and non-isobaric model that is extensively validated using experimental data from literature for different adsorption-reaction systems. For demonstrating the capabilities of the high-fidelity framework, simulations are performed for several configurations of a packed-column system containing (i) pure catalyst as in a fixed bed reactor, (ii) pure adsorbent as in a multi-step pressure swing adsorption (PSA) process, (iii) homogeneously-distributed uniform mixture of adsorbent and catalyst as in a cyclic sorption enhanced reaction process (SERP), and (iv) heterogeneously-compartmentalized adsorbent and catalyst as in a layered SERP. The model predictions show good agreement with experimental observations for sorption-enhanced steam methane reforming (SE-SMR), sorption-enhanced water gas shift reaction (SE-WGSR), PSA processes and conventional SMR. The framework is also used for evaluating the performance of a novel process with integrated SE-SMR and reverse water gas shift reaction (RWGSR) for direct natural-gas-to-syngas conversion. GRAMS is implemented such that it can be used for optimal design and intensification of novel, modular and multi-functional processes by combining multiple phenomena within a single unit.

Life cycle greenhouse gas emissions of hydrogen fuel production from chlor-alkali processes in the United States

By-product hydrogen from chlor-alkali processes can help meet the increasing demand for hydrogen fuel in early fuel cell electric vehicle markets (e.g., California) in the U.S. Hydrogen produced from chlor-alkali plants is typically combusted for process heat on site, vented to the atmosphere (i.e., wasted), or sold to the external merchant hydrogen market. Whether it is combusted, vented, or sold as a commodity, relevant information is lacking as to the life-cycle environmental benefits or trade-offs of using by-product hydrogen from chlor-alkali plants. A life-cycle analysis framework was employed to evaluate well-to-gate greenhouse gas (GHG) emissions associated with by-product hydrogen from chlor-alkali processes in comparison with hydrogen from the conventional centralized natural gas steam methane reforming (central SMR) pathway. U.S.-specific, plant-by-plant, and up-to-date chlor-alkali production characteristics were incorporated into the analysis. In addition to the venting and combustion scenarios, to deal with the multi-functionality of the chlor-alkali processes that simultaneously produce chlorine, sodium hydroxide, and hydrogen, two different co-product allocation strategies were adopted—mass allocation and market value allocation. It was estimated that by-product hydrogen production from chlor-alkali processes creates 1.3–9.8 kg CO2e/kg H2 of life-cycle GHG emissions on average, which is 20–90% less than the conventional central SMR pathway. The results vary with co-product treatment scenarios, regional electric grid characteristics, on-site power generation, product prices, and hydrogen yield. Despite the variations in the results, it was concluded that the life-cycle GHG emission reduction benefits of using by-product hydrogen from chlor-alkali processes are robust. With a diverse set of scenario analyses, the study developed a comprehensive and detailed life-cycle GHG emissions inventory of the chlor-alkali by-product hydrogen pathway and quantified sensitivity indices in the context of different assumptions and input parameter values.

A modified process for overcoming the drawbacks of conventional steam methane reforming for hydrogen production: Thermodynamic investigation

In this novel work, application of CaO sorption enhanced steam methane reforming (SESMR) for promoting hydrogen production thermally coupled with chemical looping combustion (CLC) instead of furnace for CO2 capture has been investigated to modify the conventional SMR process. In this novel process, CLC is employed to provide the necessary heat for SESMR, simultaneously achieving inherent separation of CO2 without extra energy consumed. This unprecedented technique was developed and calculated using Aspen Plus and it has been found to be favored by operating under conditions of stem to methane ratio (S/C)=4, CaO to methane ratio (Ca/C)=1 and reforming pressure of 25bar. The competitiveness of this novel configuration shows excellent advantages against dominant industrial SMR process including promoting H2 purity of product gas to be 92.6% without extra process to separate impurities from product gas, simultaneously decreasing CO and CO2 concentrations from 0.2% and 2.4% to ppm level. The overall energy efficiency of SMR and this suggested process is calculated equal to 68.02% and 85.50%, respectively; approximately 17.48% of energy efficiency is benefited from this novel process. The heat load analysis for reforming process suggests that the Ca-based sorption enhanced steam reforming process can achieve autothermal operation.

A Modified Switch-Mode Rectifier for Wide Range of Load Variations

The conventional rectifier [1] which is popularly referred as Unity Power Rectifiers (UPR)/ Boost rectifier (BR) suffers from various limitations such as low power factor, high ripple content on load voltage and increase in harmonic contents in source current due to non-linear load current that results in significant increase of total harmonic distortion (THD). The main objective of conventional SMR (i.e. shown in Fig.1) is to eliminate these problems so as to maintain unity pf, sinusoidal input current, constant dc voltage and restricted harmonic distortion based on IEEE std. To avoid the separate operation for discontinuous current mode (DCM) and continuous current mode (CCM), a mixed-mode operation [2] is proposed for wide-range of load variation. Since the ripple content on output capacitor voltage and harmonic contents in input ac current are prime concern, the authors [3] presented a robust technique to get rid of these problems. In SMR, the power flow is unidirectional and the circuit is to be operated as boost switch which enables the capacitor to keep the voltage slightly greater than peak of source voltage. But in order to double the level of capacitor voltage with respect to input voltage, a new topology [4] is proposed by Y.Neba and et.al. All these SMRs operate for resistive load, but Patil and et.al[5] changed this resistive load to induction motor to study its effect upon SMR. The mixed-mode operation [2], which has some limitations, has been overcome by modifying the SMR [6]. The topologies used [1-8] use boost inductor on dc side. So this suffers from following demerits.

A turbulent Eulerian multi-fluid reactive flow model and its application in modelling sorption enhanced steam methane reforming

A turbulent multi-fluid reactive fluid model is presented in the paper, which is a combination of a kinetic theory granular flow multi-fluid model(Chao et al., 2011) and the reaction kinetics description(Lindborg, 2008). A two dimensional in-house code was developed to simulate the gas-catalyst-sorbent three-phase reactive flow in the sorption enhanced steam methane reforming fluidized bed reactor. In the simulation, Ca-based sorbents and Ni/MgAl2O3 catalysts are used. The simulation results show that a high production of hydrogen in SE-SMR is obtained compared with the conventional SMR process. The increase of the gas fluidization velocity does not affect the purity of the product hydrogen apparently,while it can shorten the time to get to the breakthrough apparently. The increase of the steam/carbon ratio can increase the purity of the product hydrogen. A homogeneous gas temperature distribution is found which is due to the gas, particle turbulent flows and the heat balance of the SMR-CO2 adsorption reactions. These simulation results are in good agreement with the experimental results from Johnsen et al. (2006a).

Geographical distribution of road traffic deaths in England and Wales: place of accident compared with place of residence

There are two sources of information on road traffic mortality in England and Wales: ONS records giving the place of residence and police records giving the place of the accident. Use of the police records has been limited by the lack of an obvious denominator to control for population at risk. This study compares the two measures and explores the implications of using the same population denominator for both. The number of road traffic deaths occurring in 403 local authority districts in England and Wales during 1995-1999 was compared to the number of deaths to residents in the same period. Both numbers were related to the expected number of deaths to residents and selected environmental risk factors using regression techniques. Large differences were found between the number of deaths in each district and the number of deaths to residents. The expected number of deaths to residents was the strongest predictor of both observed totals. The number of deaths in the district and the number divided by expected deaths of residents were highly predictable from road accident risk factors, but the number of deaths to residents and the conventional SMR were not. Information on the place of residence of road traffic accident fatalities does not show true variations in accident risk. Police records are better for this purpose. The expected number of deaths to residents estimate provides a partial but effective and unbiased control for population effects.

Modelling and quantitative direct digital control for a DSP-based soft-switching-mode rectifier

The dynamic modelling and digital controller design for a soft-switching mode rectifier (SSMR) are presented. First, the design and implementation of an SSMR are described. This SSMR is formed from the conventional boost-type SMR by adding an auxiliary resonant branch, and zero-voltage-transition (ZVT) soft switching is achieved by applying suitably delayed pulse width modulation (PWM) signals to the main and auxiliary switches. In addition to the power circuit, sophisticated control is indispensable for the SSMR to have good sinusoidal line current tracking performance under a well-regulated DC output voltage. In dealing with the current control loop, the small-signal model is first derived using a state-space averaging method, and accordingly, the digital current-controlled PWM scheme is designed. As to the voltage control loop, its dynamic model is first estimated from measurements. Then, a quantitative design procedure is developed to find the parameters of the digital voltage controller according to the prescribed control specifications. The PWM switching scheme and the designed controllers of the SSMR are realised digitally using a DSP-based control computer. The effectiveness of the designed controllers is verified by some simulation and experimental results.

Standard and exercise metabolism and the dynamics of gas exchange in the giant red velvet mite, Dinothrombium magnificum

Although many adult insects and adult, unfed ticks are known to exchange respiratory gases discontinuously, the respiratory physiology of other tracheate arthropods is almost unknown. In this paper we present data to test hypotheses on the gas exchange dynamics, standard metabolic rate (SMR, as a function of body mass and temperature) and activity metabolism of the giant red velvet mite Dinothrombium magnificum, which according to published accounts is a predator on termites and may forage for only a few hours every year. External gas exchange in D. magnificum is continuous, unlike the case in ticks, and its locomotion energetics are typical of other small arthropods in spite of its unsegmented, flexible exoskeleton. In its aboveground state D. magnificum has a conventional arthropod SMR, disproving our hypothesis that its SMR is low, as is the case with ticks. However, we show by modeling that D. magnificum must enter a tick-like low-SMR state if it is to survive year-long fasts and if our understanding of its ecology is correct.