Reactor Temperature Research Articles

Resistive Heating Catalytic Micro-Reactor for Process Intensified Fuel Reforming to Hydrogen

Abstract Process intensification of fuel reforming using micro-reactors has become crucial for feed flexibility in H2 production for fuel cells. In the literature on microreactors, energy supply for these endothermic reactions has faced limitations, relying on external heating, or autothermal operation. This paper explores a novel approach using a thin-film catalytic heater to develop micro-reactors. The study focuses on dry methane reforming in a simplified micro-reactor where thermal energy is supplied through electric resistive heating of a thin carbon sheet with a catalyst applied to its surface. The thin catalytic heated layer inside the reactor minimizes energy losses and the reactor footprint. Power input was varied from 90-225 W to understand its impact on the reactor temperature, CH4 conversion, H2 and CO yields. Fast thermal response times were achieved using the carbon paper as thin film for heating. Ni/MgO impregnated onto carbon paper was utilized as the catalytic heating element which resulted in CH4 conversions greater than 60% at temperature above750 K. Influence of operating conditions such as the input molar ratio of CO2/CH4, and gas hourly space velocity (GHSV) were also investigated to understand the scope of the catalyst in this setup. High GHSVs (592,885 and 948,617 mL/(hr.gcatalyst)) were tested to understand the throughput achievable using this setup. This approach demonstrates improved scope and feasibility for further intensification compared to conventionally heated microreactors. The research paves the way for efficient and compact micro-reactors for fuel reforming processes.

Study of physical parameters on Sargassum liquid fertilizer production and its nutrient contents

Abstract Sargassum can be used as an alternative material for liquid organic fertilizer production. Liquid organic fertilizer is more environmental-friendly than the synthetic one. In the previous research, we have reported that Sargassum from Lange Beach (Aceh Besar, Aceh, Indonesia) was potential as a source of nutrients for plants. This current work aims to evaluate the levels of plants growth hormones including auxin, cytokinin, and gibberellin. Furthermore, we also evaluated the levels of macronutrients of the Sargassum liquid fertilizer (SLF) obtained from a twenty-five-day fermentation compared with the Indonesian Agricultural Ministry Regulation of Permentan no. 70/SR./140/10/2011. Using a high-performance liquid chromatography (HPLC) analysis, we reported that the levels of auxin, cytokinin, and gibberellin were 2.546 ± 0.399 ppm; 130.093 ± 0.378 ppm; and 13.456 ± 0.783 ppm, respectively. In addition, the contents of nitrogen (N), phosphorus (P), and potassium (K) as macronutrients were 1.79 ± 0.25 %; 0.025 ± 0.005 %; and 0.15 ± 0 %, respectively. Our study also measured the physical parameters of the reactor, such as temperature and humidity, when the production was taking place. Reactor temperature during the production process was in between 31 and 32°C. Meanwhile, the humidity was in between 87 and 89%. In conclusion, this work demonstrated that SLF produced from Lange’s Sargassum had sufficient nutrients needed by plants according to the national regulation.

Ciprofloxacin adsorption onto Pumice-bentonite composites: Modeling, kinetics, equilibriums and reusability studies

BackgroundA new Bentonite-loaded Pumice adsorbent (P-BNT3) was successfully synthesized as an efficient adsorbent for CIP removal from aqueous solutions. MethodsIn the present study, P-BNT3 composite synthesized by hydrothermal technique (24 h @160 °C) was loaded with Bentonite (BNT) using ultrasonication (20 min @25 °C) to remove CIP antibiotic. P-BNT3 composite was characterized by FTIR, XRD, BET, TGA, SEM, and TEM analyses. XRD, SEM, and TEM analyses indicate effective coupling of Pumice/ BNT strong layers with highly porous heterogeneous structure. Adsorption of CIP is studied as a function of pH, dosage, contact time, initial CIP concentration, and temperature in a batch reactor to obtain the maximum adsorption capacity (qm). Significant FindingsA MFSO kinetic model (R2= 0.983) and Langmuir and Dubinin–Radushkevich isotherm model (R2= 0.989 and 0.986) provide good fits to the experimental. The highest amount of CIP adsorbed is 54 mg/g at pH=2.0, which is 5 folds higher than pristine Pumice. The adsorption equilibrium was attained in 240 min with P-BNT3 for a CIP concentration of 30 mg/L. The characterization of spent composites after CIP adsorption suggested that CIP adsorption onto P-BNT3 composite is governed by π-π interaction, chemical complexation, and surface interactions. Based on thermodynamic investigation over the temperature range of 298 ̶ 318 K, CIP adsorption on P-BNT3 was a spontaneous (-ΔG°) and endothermic (ΔH°=+5.313) phenomenon. Furthermore, the adsorption-desorption procedure demonstrated that the composite could be efficiently reused up to 5 times. However, expensive desorption costs and the inevitable secondary effluent are a challenge in the practical implementation. Based on the findings, the P-BNT3 composite has great potential for the removal of other pharmaceutical compounds.

Process Integration of Hydrogen Production Using Steam Gasification and Water-Gas Shift Reactions: A Case of Response Surface Method and Machine Learning Techniques

An equilibrium-based steady-state simulator model that predicts and optimizes hydrogen production from steam gasification of biomass is developed using ASPEN Plus software and artificial intelligence techniques. Corn cob’s chemical composition was characterized to ensure the biomass used as a gasifier and with potential for production of hydrogen. Artificial intelligence is used to examine the effects of the significant input variables on response variables, such as hydrogen mole fraction and hydrogen energy content. Optimizing the steam-gasification process using response surface methodology (RSM) considering a variety of biomass-steam ratios was carried out to achieve the best results. Hydrogen yield and the impact of main operating parameters were considered. A maximum hydrogen concentration is found in the gasifier and water-gas shift (WGS) reactor at the highest steam-to-biomass (S/B) ratio and the lowest WGS reaction temperature, while the gasification temperature has an optimum value. ANFIS was used to predict hydrogen of mole fraction, 0.5045 with the input parameters of S/B ratio of 2.449 and reactor pressure and temperature of 1 bar and 848°C, respectively. With the steam-gasification model operating at temperature (850°C), pressure (1 bar), and S/B ratio of 2.0, an ASPEN simulator achieved a maximum of 0.5862 mole fraction of hydrogen, while RSM gave an increase of 19.0% optimum hydrogen produced over the ANFIS prediction with the input parameters of S/B ratio of 1.053 and reactor pressure and temperature of 1 bar and 850°C, respectively. Varying the gasifier temperature and S/B ratio have, on the other hand, a crucial effect on the gasification process with artificial intelligence as a unique tool for process evaluation, prediction, and optimization to increase a significant impact on the products especially hydrogen.

Process development in Quality‐by‐Design paradigm for anti‐solvent aided crystallization: impact of crystallization parameters on particle morphology and dissolution behaviour of Dexlansoprazole active pharmaceutical ingredient

AbstractBACKGROUNDIn this work, a process development study for the crystallization step of dexlansoprazole API has been demonstrated under the Quality‐by‐Design (QbD) paradigm. Dexlansoprazole (crystalline) samples prepared under different crystallization conditions of reactor temperature and addition time of anti‐solvent were subjected to solid‐state characterization with variety of analytical techniques, including X‐ray powder diffraction (XRPD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), dynamic vapour sorption (DVS), scanning electron microscopy (SEM), particle size distribution (PSD) by laser diffraction and intrinsic dissolution rate (IDR).RESULTSThe crystalline samples were observed to have identical polymorphic phase integrity but differed in their physical characteristics. The particle size distribution and microscopy data collectively elucidated the particle growth kinetics and the extent of agglomeration could be correlated to crystallization conditions, namely reactor temperature and addition time of anti‐solvent. The intrinsic dissolution rate of samples was in good agreement with the morphological properties.CONCLUSIONAn empirical model has been proposed for intrinsic dissolution rate correlating with crystallization process parameters. In conclusion, it was possible to elucidate the impact of crystallization parameters on the solid‐state behaviour of dexlansoprazole for development of appropriate pharmaceutical dosage forms. © 2024 Society of Chemical Industry (SCI).

Thermal-hydraulic characteristics analysis of unprotected accident and protection control strategy for helium-xenon cooled reactor system

The small modular helium-xenon cooled reactor has the advantages of simple and compact system structure, short construction cycle, light weight and small volume, which is very suitable for energy supply in remote area and small nuclear propulsion device. The research on accident characteristics and protection control strategies is very important to ensure the safe and reliable operation of the reactor system and mitigate the consequences of the accident. Therefore, the safety characteristics analysis program of helium-xenon cooled reactor system is developed based on Modelica language, and the transient verification of typical working conditions is carried out. The maximum relative error of the verification results was 7.91 %. Through the program, the unprotected transient conditions and corresponding protection control strategy transient conditions of external load loss accident, partial loss of heat sink accident, main valve accidental closing accident and Brayton unit efficiency step decline accident are simulated. The results show that the loss of all external loads will lead to rotation speed overspeed. The introduction of negative reactivity or bypass control can effectively control the rotation speed rise, but the introduction of negative reactivity is better than bypass control. Under unprotected control, the partial loss of the heat sink, the accidental closing of the main valve and the step down of the Brayton unit efficiency will all lead to the rapid decline of the rotation speed and mass flow rate, and there is a risk of the reactor temperature exceeding the limit. The rotation speed and mass flow rate can be effectively stabilized by load following to prevent the temperature exceeding the limit.

Process modelling for the production of hydrogen-based direct reduced iron in shaft furnaces using different ore grades

This process modelling study explored the behaviour of hydrogen-based direct reduced iron (DRI) manufacturing in a shaft furnace. Various performance parameters such as metallisation ratio (MR), consumption of hydrogen per tonne of DRI, production of by-products, reactor energy demand and total energy demands for the process have been analysed with respect to temperature, ore grade (gangue content), and reactant conditions. The HSC Chemistry (H: enthalpy, S: entropy and C: heat capacity) SIM (simulation) module was employed for the modelling coupled with the Gibbs energy minimisation calculation. The shaft furnace was divided into three zones to model the three-step reduction of iron ore in a counterflow arrangement. Results show that temperature and hydrogen supply have a significant effect on the metallisation of DRI. Increasing temperature and hydrogen flow rate were predicted to increase the MR or reducibility. A full metallisation can be achieved with hydrogen supply of 130, 110, 100 and 90 kg/tDRI at 700, 800, 900 and 1000°C, respectively, using the best-grade ore (Fe 69 wt.%, gangue 5.2 wt.%). However, the hydrogen consumption in full metallisation was calculated to be 54 kg/tDRI (tonne of DRI). At full MR, the reactor energy consumption (supplementary electrical energy) was calculated to be 0.56 to 0.59 MWh/t Fefeed using the reactor temperature from 700 to 1000°C. Ore grade or gangue content has a significant impact on reactor energy demand. For example, at 900°C, the top-grade ore was calculated to consume 0.69 MWh/tDRI compared to 0.88 MWh/tDRI using the lowest grade ore. A certain percentage of CO (i.e. 15%) blended with hydrogen was predicted to be beneficial for metallisation, hydrogen consumption, and overall energy demand. However, increasing CO would increase CO2 emissions significantly.

Feedback control of an experimental electrically-heated steam methane reformer

Steam methane reforming (SMR) is the most common industrial process to produce hydrogen (H2) from methane and water vapor. The SMR reactions are overall highly endothermic and traditionally, fossil fuels are burned to provide the necessary heat of reaction. However, it was found that electrifying the tubular SMR reactors using renewable electrons instead of conventional heating gives the opportunity of producing H2 with lower carbon emissions, lower reactor volumes, and higher carbon conversion. While current studies in this new technology focus on improving the catalysts or heating sources, a more efficient process control scheme can also significantly contribute to the understanding of potential challenges and opportunities of combining renewables and natural gas in the production of H2 at industrial scales. In order to further develop the electrically-heated SMR process and the associated control strategies, we have constructed an experimental Joule-heated SMR system at UCLA. The system contains a tubular reactor with a washcoated Ni/ZrO2 catalyst, two thermocouples connected to the top and bottom of the reactor, a power supply for providing electrical heating, and an on-line gas chromatograph (GC) for measuring outlet gas concentrations. The synthesis procedure of the catalyst, SMR data collection, and thermal considerations for catalyst degradation are described in this paper and are all accounted for experimentally when using a proportional integral (PI) controller to gradually increase the reactor temperature without harming the catalyst. Advanced control strategies, such as model predictive control (MPC), require a process model that uses measurement feedback to make predictions of the process time-evolution in order to optimize the control actions in real-time. We have previously developed a lumped-parameter modeling strategy for the SMR process. The MPC objective is to control the H2 production rate by manipulating the current flowing through the outer reactor shell. However, to use this model in an MPC, feedback values for all state variables should be provided by the sensors. In our experimental system, the on-line GC only gives discrete measurements with a long sampling period. To this end, the process model is incorporated into an extended Luenberger observer (ELO) that uses the reactor temperature and GC measurements to provide estimates of all the variables needed by the MPC. The ELO-based MPC system is then experimentally implemented on the process and it is demonstrated to be more efficient in terms of speed of the closed-loop response than the PI controller using delayed, measurement feedback by the GC.

Aspen Simulation Study of Dual-Fluidized Bed Biomass Gasification

This article establishes a thermodynamic model of a dual-fluidized bed biomass gasification process based on the Aspen Plus software platform and studies the operational control characteristics of the dual-fluidized bed. Firstly, the reliability of the model is verified by comparing it with the existing experimental data, and then the influence of different process parameters on the operation and gasification characteristics of the dual-fluidized bed system is investigated. The main parameters studied in the operational process include the fuel feed rate, steam/biomass ratio (S/B), air equivalent ratio (ER), and circulating bed material amount, etc. Their influence on the gasification product composition, reactor temperature, gas heat value (QV), gas production rate (GV), carbon conversion rate (ηc), and gasification efficiency (η) is investigated. The study finds that fuel feed rate and circulating bed material amount are positively correlated with QV, ηc, and η; ER is positively correlated with GV and ηc but negatively correlated with QV and η; S/B is positively correlated with GV, ηc, and η but negatively correlated with QV. The addition of CaO is beneficial for increasing QV. In actual operation, a lower reaction temperature in the gasification bed can be achieved by reducing the circulating bed material amount, and a larger temperature difference between the combustion furnace and the gasification furnace helps to further improve the quality of the gas. At the same time, GV, ηc, and η need to be considered to find the most optimized operating conditions for maximizing the benefits. The model simulation results agree well with the experimental data, providing a reference for the operation and design of dual-fluidized beds and chemical looping technology based on dual-fluidized beds.

Can Aluminum Cations Promote Nucleation for THF Hydrate Growth?

Rapid nucleation of tetrahydrofuran (THF) hydrate is essential for developing a THF hydrate-based cold storage technology. Earlier works have hypothesized the role of aluminum complexes in initiating the nucleation of clathrate hydrates using aluminum metal electrodes and substrates. This study investigates if the nucleation promotional effect of hydrate can be achieved using the aluminum salt, AlCl3, due to the formation of aluminum aqua complexes in water. Metal chlorides NaCl and MgCl2 are also utilized to evaluate the effect of cation type in initiating nucleation, i.e., the effect of charge/radius ratio. The induction time is measured in a stirred reactor at various subcoolings and concentrations of 0.05, 0.1, 0.5, 1, and 2 wt %. The nucleation time is studied in two reactor configurations based on the nature of salt introduction in the THF solution, i.e., salt premixed in solution and salt injected inside the solution. The sudden rise in the reactor temperature due to hydrate formation is used as an indicator of hydrate formation. Results indicate that AlCl3 promotes hydrate nucleation as AlCl3 reduces induction time by 92.2% at 0.05 wt % concentration compared with water. Nearly instantaneous nucleation is also achieved by directly injecting AlCl3. MgCl2 and NaCl do not show a similar effect on induction time as AlCl3. The pH and Raman spectra measurements with and without salts are carried out to explain the effect of cations on the THF-water solution.

Temperature control strategy for safer and heat-efficient operations in a catalytic flow reactor

A new temperature control strategy for a packed-bed tubular reactor was proposed. Case studies of a highly exothermic 1st-order reaction and an actual 2nd-order reaction were conducted using the computational fluid dynamics software COMSOL Multiphysics® 4.4. Through the simulation, the important factors for reactor temperature control were confirmed, which were the parameters related to heat transfer. Based on the ratio of the heat generation rate to the heat transfer rate, a new dimensionless number was proposed for controlling the temperature increase within an acceptable range in a reactor. Through case studies, the validity of the proposed dimensionless number was confirmed, and an important value of a proportionality constant was derived from the results. Using the proposed dimensionless number, a reactor size can be maximized within an acceptable temperature increase. The results obtained in this study are expected to provide important guidelines for temperature control and maximization of production using flow reactors.

Effect of Feed Mass, Reactor Temperature, and Time on the Yield of Waste Polypropylene Pyrolysis Oil Produced via a Fixed-Bed Reactor.

This paper presents the results of investigations into the pyrolysis of waste polypropylene in a laboratory fixed-bed batch reactor. The experiments were designed and verified in such a way as to allow the application of the response surface methodology (RSM) in the development of an empirical mathematical model that quantifies the impacts mentioned above. The influence of the mass of the raw material (50, 100, and 150 g) together with the reactor temperature (450, 475, and 500 °C) and the reaction time (45, 50 and 75 min) was examined. It has been shown that the mass of the raw material, i.e., the filling volume of the reactor, has a significant influence on the pyrolysis oil yield. This influence exceeds the influence of reactor temperature and reaction time. This was explained by observing the temperature change inside the reactor at three different spots at the bottom, middle, and top of the reactor. The recorded temperature diagrams show that, with greater masses of feedstock, local overheating occurs in the middle part of the reactor, which leads to the overcracking of volatile products and, from there, to an increased formation of non-condensable gases, i.e., a reduced yield of pyrolytic oil.

Process simulation, optimization, and cost analysis of a proposed sulfur recovery unit by applying modified Claus technology

Removing sour gas from any suitable gas sweetening technology in a cost-effective and environmentally responsible manner is a major challenge. This paper discusses how to safely and economically dispose of small amounts of acid gases resulting from the amine sweetening process. A two-stage Claus desulfurization unit was studied and simulated to treat acid gases resulting from natural gas sweetening operations in Ras Gharib oil fields (Egypt). These acid gases are used as feedstock for the proposed plant to produce a valuable product, such as elemental sulfur, which is used as a raw material in many industries. Although many sulfur recovery techniques are available for various conditions and applications, the Claus process is a critical and widely used method for recovering elemental sulfur from gaseous hydrogen sulfide. This work represents the potential benefits of treating acid gases with high hydrogen sulfide content. In addition, operational variables that could affect sulfur production and sulfur recovery efficiency of the studied Claus unit were studied and optimized. Aspen HYSYS simulation software (version 9) was used to evaluate the economic aspects and optimize the operational parameters of the unit for producing sulfur from acid background gases. The results showed that the maximum sulfur production was achieved at a catalytic converter reactor temperature of 270 °C and 210 °C for the first and second catalytic reactor, respectively, with an air flow rate of 933.3 kg mol/h. The economic study of the proposed desulfurization unit showed that the Claus unit would be economically acceptable with an expected return on investment of approximately 10% and an average payback period of 10 years. Moreover, the introduced plant has a positive impact on the environment by reducing the concentration of hydrogen sulfide in the gas from 69.58 to 0.16%.

Effect of calcination temperature on the performance of K-Co/Al2O3 catalyst for oxidative coupling of methane

The oxidative coupling of methane (OCM) involves directly converting methane to C2+ hydrocarbons (such as ethylene and ethane) via a reaction with oxygen. This study elucidated the effect of the calcination temperature on the structure and catalytic performance of potassium-doped-cobalt oxide supported on an alumina (K-Co/Al2O3) catalyst for the OCM reaction. The catalyst was highly active at relatively low reactor temperatures (500–640 °C). Four calcination temperatures (400, 500, 600, and 700 °C) were investigated, with the results showing that the calcination temperature strongly affected catalytic properties, such as the crystalline phases, elemental distribution, physical properties, and catalytic basicity, leading to a wide range in catalytic performances. The catalyst calcined at 400 °C was superior among the catalysts, with 8.3 % C2+ yield, 24.8 % C2+ selectivity, and 33.6 % CH4 conversion at 640 °C. Furthermore, the catalyst was robust over 24 h of testing.

Transformation of biomass and waste plastic mixtures into hydrocarbon oils and gases by pyrolysis using different reactor temperatures and pressures

In this work the laboratory scale pyrolysis and gasification of biomass and plastic waste mixtures were investigated at different temperatures (450°C and 750°C) and reactor pressures (0.1 bar and 1.0 bar). The main decomposition reactions and the effect of the process parameters were followed through the product yields and compositions of gases and pyrolysis oils. Less residue and significantly more gases had been found at higher temperature, which phenomena was more notable in case of higher proportion of plastic waste in the raw material mixtures. The concentration of hydrogen in gases changed by opposite trend at 450°C and 750°C as function of biomass ratios. The hydrogen and CO ratio can also increase by the increasing in plastic proportion of raw materials at both temperatures and pressures. Regarding the pressure, it can increase the pyrolysis and gasification reactions resulted higher yields of gases and lower oil/water ratios. More hydrogen and less C2-C6 compounds were found using 0.1 bar reactor pressure. Pyrolysis-oil contained aliphatic and aromatic hydrocarbons; n-paraffin, n-olefin, aldehyde, ketones, alcohols, phenols, carboxylic acids, etc. Due to deoxygenation reactions, hydrocarbons with less oxygen-containing compounds were found at 0.1 bar pressure.

Enhancing solubility of polymer-loaded febuxostat through ultrasound-assisted microfluidic antisolvent nanoprecipitation: Optimization using Box-Behnken design

Febuxostat (FEB) nanoparticles with the use of poloxamer 407 were prepared using ultrasound assisted microfluidic nanoprecipitation method to enhance febuxostat's solubility and bioavailability. The optimization for this purpose was conducted using the Box Behnken design (BBD) approach. Four factors and three level BBD was used to study the interactive and individual effect of ultrasonic frequency (X1), amplitude (X2), Ultrasound assisted microfluidic reactor (USMR) temperature (X3), and micromixer confluence angle (X4) on selected two responses. Particle size (Y1) and encapsulation efficiency (% EE) (Y2) were the desired responses. The formulated FEB nanoparticles were analyzed by Fourier Transform Infrared Spectroscopy (FTIR) and Transmission Electron Microscopy (TEM). The minimum nanoparticle size, 7.156 nm with 0.22 polydispersity index (PDI) was attained for FEB-loaded polymer nano-sized particles. To investigate the drug release rate (% DR), fast-dissolving tablets of raw FEB and optimized FEB formulation were prepared. A 1.25-fold improvement in FEB solubility rate was experimentally achieved compared to raw FEB. No chemical interaction between the drug and polymer was observed using FTIR. Optimized FEB formulation showed a 92.94 % release rate of the drug in 90 min with 91.70 % EE.

Unlocking waste potential: A neural network approach to forecasting sustainable acetaldehyde production from ethanol upcycling in biomass waste gasification

The upcycling of biomass waste gasification process for ethanol and acetaldehyde production has been augmented by integrating secondary and tertiary processes. A simulation model using Aspen Plus, developed from experimental investigations to assess the viability of this proposed system. Furthermore, this model has been utilized to create an Artificial Neural Network (ANN) prediction model. Process sustainability analysis demonstrated an energy efficiency of 64 % while economic viability up to 80 % process efficiency with an Internal Rate of Return (IRR) of 6 % and a payback period of 2107 days. An optimization strategy and an artificial neural network (ANN)-based predictive model have been developed. Optimization results revealed that a gasifier temperature of around 600 °C, a gasifying agent ratio of 2.0, and an acetaldehyde reactor temperature of 300 °C yield better process outcomes and revenue. The ANN model exhibited robust performance with coefficient of determination (R2) values ranging from 0.92 to 0.98 for acetaldehyde, hydrogen, and total revenue. Mean absolute error (MAE) and mean absolute percentage error (MAPE) fell within the range of 0.03–0.1 and 0.1–1.12 %, respectively. Consequently, given the favorable sustainability and predictive model performance, this study can be used for similar endeavors.

Straw pyrolysis for use in electricity storage installations

A concept has been proposed for an installation designed to store excess electricity periodically occurring on the grid. Excess electricity will be used for straw pyrolysis. The main pyrolysis product, gas, will be used to generate electricity using a combustion generator to feed back power into the grid during periods of shortage. The resulting biochar from the pyrolysis can be introduced into the soil to improve soil quality and play a significant role in carbon sequestration. The system uses an electrically heated reactor with a screw conveyor.To preliminarily assess the feasibility of this system, experiments were carried out using wheat straw at temperatures of 300, 400, 500, 600, and 700 °C for the pyrolysis reactor. The resulting gas-to-feedstock mass ratio ranged from 29.04 % at 300 °C to 52.7 % at 700 °C reactor temperature, the biochar mass yield ratio to feedstock varied from 39.41 % to 27.36 % (at 700 °C), and the pyrolysis liquid ranged from 31.55 % to 27.36 % (at 700 °C). The pyrolytic liquid contained a high water content relative to its mass, reaching up to 95.2 % at 700 °C, rendering it less suitable as an energy feedstock.At a reactor temperature of 700 °C, the energy value of the gas produced from the feedstock was twice that of the electricity used for the pyrolysis process. These results suggest the feasibility and operation of the proposed installation.

Simulated safety analysis of a total loss of feedwater accident in the steam generator of CPR1000 nuclear power plant

As M310 series units, CPR1000 Nuclear Power Plant in China is also the first batch of demonstration nuclear power plants in China to try out SOP(the state-oriented procedure) accident procedures. The establishment of SOP accident regulations is an important work to mitigate the consequences of radioactive accidents in the design of nuclear power plants, and it is also the embodiment of the defense-in-depth requirements in the implementation of nuclear safety regulations. It can handle superimposed accidents, human errors in program implementation and events not considered in the primary cause sequence. In order to study the efficiency of its upgraded SOP procedure and its ability to deal with severe accidents, the typical primary cause event of severe accidents in nuclear power plants–such as the total loss of feedwater accident of steam generators has been adopted for research. The initial state of the simulation is the full power operation of the nuclear power plant, the simulation process is from the loss of all the water supply accidents to the whole accident processing. A total of 30 simulation experiments were carried out. The temperature and pressure of the key parameters obtained are the average values of 30 simulation experiments. The stability and efficiency of the updated SOP are evaluated by the treatment time of the water supply loss accident and the changes of reactor temperature and pressure after the accident. The results show that the upgraded SOP procedure is more stable and efficient. The upgraded SOP procedure, when dealing with other types of accidents, has improved the treatment of residual heat conduction in the core, increased the efficiency of accident treatment, and enhanced the safety of the reactor. At the same time, based on the weaknesses of the upgraded SOP procedure, constructive suggestions on changing the setting value of the steam generator bypass valve have also been put forward accordingly. Furthermore, it can be concluded from many simulated accidents that this change will win about 5% more of the disposal time for nuclear power plants under accidents, which provides references for the subsequent upgrading of M310 series power plant procedures.

Estimation-based model predictive control of an electrically-heated steam methane reforming process

The surge in demand for hydrogen (H2) across diverse sectors, including clean energy transportation and chemical synthesis, underscores the need for a thorough investigation into H2 production dynamics and the development of effective controllers for industrial applications. This paper focuses on an electrically heated steam methane reforming (SMR) process for H2 production, offering advantages such as enhanced environmental sustainability, compactness, efficiency, and controllability compared to conventional reforming methods. Electric heating of the entire system allows for adjustments in current to control reactor temperature, thereby impacting hydrogen production rates. However, accurately modeling hydrogen production dynamics presents a formidable challenge, as complex models with high precision are computationally unsuitable for real-time control integration. Considering these factors, an accurate and efficient first-principles-based lumped-parameter model is developed to provide a dependable estimation of hydrogen production in an electrically-heated steam methane reformer. This model is validated experimentally and then utilized in a model predictive controller (MPC). To obtain the necessary state estimate information for the MPC, an extended Luenberger observer (ELO) method is employed to estimate state variables from limited, infrequent and delayed measurements of gas-phase reactor outlet stream and frequent measurements of the reactor temperature. Simulation comparisons with a proportional-integral (PI) controller reveal a much faster response in achieving the desired H2 production rate under the estimation-based MPC. Additionally, the simulations demonstrate the robustness of the controller to process variability such as a decrease in catalyst activation energy, commonly encountered in the SMR process, highlighting its effectiveness in maintaining stable operation under varying process conditions.