Basic Reactor Research Articles

Modeling an Industrial Hydrochlorination of Glycerol – A Systematic Study of Basic Reactor Types

AbstractModeling and optimization of real chemical reactors is challenging. A program to systematically compare the performance of an existing reactor with basic reactor models was built. The program was tested on the hydrochlorination of bio‐based glycerol in a bubble column. The model‐based approach provided insights into the reactor's concentration profiles, mass transfer, and mixing. In this case study, a plug‐flow tubular reactor (PFTR) is sufficient as a model for process intensification. Based on the results, a novel reactor design that significantly improves yields was proposed and simulated.

Innovative process for sulphur recovery from waste incineration flue gases: production of marketable sodium bisulphite solution

ABSTRACT This study presents an innovative process for recovering sulphur from hazardous waste incineration flue gases, designed to produce a marketable sodium bisulphite solution while ensuring complete SO2 removal. This new process is characterized by a double absorption strategy at two different pH levels. The first step, at an acidic pH, generates the desired bisulphite solution, while the second step, at a basic pH, produces the sulphite solution for recycling into the first step and ensures total SO2 removal. The process’s performance and feasibility were evaluated on a laboratory scale using a batch reactor with synthetic gas. The parametric study focused on the initial sulphite concentration in the absorption solution and the reactor temperature. A removal efficiency exceeding 95% was achieved across all initial sulphite concentrations and temperature ranges, when the pH was maintained above 6. At pH 5, where bisulphites are the predominant sulphur species, the removal efficiency remained substantial at approximately 70%. The oxidation of sulphites/bisulphites by oxygen in the flue gases was minimal, with less than 5% conversion to sulphate. Additionally, pH-controlled experiments were conducted to optimize plant start-up procedures. For the basic reactor, starting with water and adjusting the pH to 8 during SO2 absorption effectively minimized sodium hydroxide consumption. In contrast, for the acidic reactor at pH 5, initiating the process with a concentrated sulphite solution resulted in more stable absorption rates. These findings underscore the process's potential for efficient sulphur recovery and highlight the importance of pH management in optimizing operational stability and chemical consumption.

Applicability and Validity of CFD‐based Compartment Models for One to Multiple Operating Points

AbstractCFD‐based compartment (CPT) models offer a promising modeling method and trade‐off between computational effort and required accuracy. The models combine the relevant fluid dynamics from the computational expensive CFD and the incorporation of complex reaction mechanisms usually used in basic reactor models. However, one criticism is their reliance on specific operating points, rendering them invalid when boundary conditions change. This study explores using a CFD‐based CPT model for static mixing elements across multiple operating points by making use of the creeping flow. The mean age theory facilitates a comprehensive comparison between CFD and CPT models. Results indicate that within this flow region, the CPT model can be extrapolated to other operating points via linear scaling.

How important is reactor design for CO2 conversion in warm plasmas?

In this work, we evaluated several new electrode configurations for CO2 conversion in a gliding arc plasmatron (GAP) reactor. Although the reactor design influences the performance, the best results give only slightly higher CO2 conversion than the basic GAP reactor design, which indicates that this reactor may have reached its performance limits. Moreover, we compared our results to those of four completely different plasma reactors, also operating at atmospheric pressure and with contact between the plasma and the electrodes. Surprisingly, the performance of all these warm plasmas is very similar (CO2 conversion around 10 % for an energy efficiency around 30 %). In view of these apparent performance limits regarding the reactor design, we believe further improvements should focus on other aspects, such as the post-plasma-region where the implementation of nozzles or a carbon bed are promising. We summarize the performance of our GAP reactor by comparing the energy efficiency and CO2 conversion for all different plasma reactors reported in literature. We can conclude that the GAP is not the best plasma reactor, but its operation at atmospheric pressure makes it appealing for industrial application. We believe that future efforts should focus on process design, techno-economic assessments and large-scale demonstrations: these will be crucial to assess the real industrial potential of this warm plasma technology.

THE ROLE OF SOVIET JEWS IN BUILDING THE ISRAELI NUCLEAR ARSENAL (THE DIMONA REACTOR AS A MODEL) NINEVEH EDUCATION DIRECTORATE

The Israeli nuclear file is considered one of the biggest secrets of nuclear life in the world, if (Israel) refuses, since its establishment,to be included in the periodic inspections conducted by the Atomic Energy Agency on nuclear facilities in the world, just as its government refuses to sign the Nuclear Non-Proliferation Treaty signed by the Arab countries. Which makes the Israeli nuclear file (out of coverage). (Israel) possesses a basic nuclear reactor، as it was the first step it took regarding the establishment of a nuclear force in late (1948)AD and early (1949)AD. The most important and most dangerous effective step taken by (Israel) on the road to producing nuclear weapons for nuclear energy in(Israel)was its establishment of(the Dimona reactor.). This reactor was built according to French designs drawn up by the French atomic Energy Commission as part of the French-Israeli efforts to coordinate in the field of atomic cooperation. The Dimona reactor is located on the desert road between Beersheba and Sodom، in the Negev Center for Nuclear Research. It consists of ten buildings. It contains a nuclear reactor and a reprocessing plant. Plutonium This place was chosen because of its proximity to the raw materials (uranium) found in the Negev desert. The costs of building the reactor were estimated at about (130) million dollars, and its capacity was (150) megawatts, and it was able to produce (8) kilos of plutonium annually. The reactor operates with enriched uranium. (90%), which is a reactor that produces plutonium، which is the main element for the production of the fissile atomic bomb, since the Jews of Russian origins had a great and most prominent influence in the establishment of the Israeli nuclear program, as they pushed the Israeli nuclear file into existence. And they put (Israel) at the forefront of the nuclear countries

Countercurrent moving bed carbonator for CO2 capture in decoupled calcium looping systems

Calcium Looping can be a suitable technology to address the CO2 capture from disperse flue gas sources, including shipping, by decoupling carbonation and calcination steps and by using the CaCO3 as CO2 transport media. In this work we present the design of a moving bed carbonator especially suited for these applications. The Ca-sorbent material (porous CaO or Ca(OH)2 in the form of pebbles or pellets) is fed to the top of the reactor at ambient conditions and is preheated by the gases leaving the reactor. Then the carbonated solids leave the reactor at the bottom at a temperature close to that of the inlet gases. A basic countercurrent reactor model has been developed to identify operational windows and other suitable conditions to achieve optimum carbonation temperatures of 600–700 °C in the central carbonation zone of the reactor. Gas velocities of 1–3 m/s and solid residence times in the carbonation zone of between 2 and 13 h are needed to carbonate spheres of Ca-based materials of 1 to 2 cm up to its maximum conversion of 0.6 for CaO and 0.8 for Ca(OH)2. The thermal and mechanical similarities of the proposed reactor with those of shaft kilns should accelerate the scaling up of this new reactor concept.

Analysis of Operation Conditions of Ca(OH)2 Entrained Carbonator Reactors for CO2 Capture in Backup Power Plants.

The share of renewables in the energy sector is increasing, and energy storage and backup power combustion systems to cover the periods of time with low renewable energy production are becoming increasingly needed. Flexible calcium looping configurations based on the storage of solids are a promising alternative to capture the CO2 produced in such backup combustion systems. The use of Ca(OH)2 instead of CaO is better suited to these applications due to the faster reaction kinetics and higher carbonation conversions as Ca(OH)2 in powder form can achieve conversions of up to 0.7 in just a few seconds at temperatures of 550–650 °C. To take advantage of these fast reaction kinetics, compact carbonator reactors with short gas–solid contact times (i.e., a few seconds) can be designed. However, the low enthalpy of the carbonation reaction of Ca(OH)2 makes it challenging to find the optimum conditions which maximize the CO2 capture efficiency. In this work, a basic entrained reactor with recent experimental reaction kinetics has been used to determine suitable operational windows for this kind of carbonator. CO2 capture efficiencies above 90% can be achieved for flue gases with low CO2 concentrations (4%v CO2) when they are fed into the carbonator at temperatures of around 500–600 °C while maintaining low FCa/FCO2 ratios (<2) and feeding the sorbent at ambient temperature. When capturing from a flue gas with a higher CO2 concentration (14%v CO2), the sorbent needs to be fed at higher temperatures to effectively capture CO2 in short contact times (i.e., 6 s).

A novel concept of Vertical Up-Flow Forward Osmosis reactor: Design, performance and evaluation

Performance of the forward osmosis (FO) process is limited due to the decline in water flux and increase in reverse salt flux. In this study, a novel Vertical Up-Flow Forward Osmosis (VUF-FO) reactor was designed and evaluated for eight different contacting patterns of feed and draw agent (DA). The best contacting pattern was compared with the basic H-shape reactor. Pulsating inlets were used for the recirculation of the feed and DA which helped in improving the performance by reducing the concentration polarization on membrane. Water flux in FO (active layer facing feed side) and PRO (active layer facing draw side) mode was 12.75 and 16.28 L/m2hr (LMH) respectively for the contacting pattern R3 and R5 after 8 h of the process. While the water flux in the H-shape reactor was 9.12 and 12.54 LMH for FO and PRO mode respectively. Diffusional behavior of water flux and reverse salt flux were also evaluated for both the FO reactors. Water flux in the H-shape reactor was declined to more than 60% from its initial value in both the modes (i.e. FO and PRO) due to the concentration polarization on membrane. Only 10% decline in water flux was observed for the VUF-FO reactor. This showed a better consistency of water flux in the VUF-FO reactor. The reverse salt flux in the VUF-FO reactor was less than 85% compared to the H-shape reactor. Therefore, a novel designed reactor improved the overall performance of FO in terms of water flux and reverse salt flux.

Deactivation Kinetics of ZSM‐5 by Coke in Ethanol‐to‐Hydrocarbons Process

AbstractConversion of ethanol to hydrocarbons by porous zeolite ZSM‐5 is a sustainable alternative compared to crude oil, gas or coal conversion. A quantification and description of micro‐ and macroscopic deactivation kinetics with basic transport and reactor models reveals deeper insight into the dynamics of coking and product formation at varying contact time. A new first order deactivation model helps to separate linear deactivation and autocatalytic acceleration of catalyst decay. A deeper look into product formation reveals a change in selectivity during initiation and deactivation phase from bigger build‐up C5+ to smaller cracking products C3 after formation of coke precursors, which does not coincide with site‐loss and reduction of contact time alone. Thereby, deactivation and switching selectivity in the hydrocarbon pool concept become more deterministic, which paves the way to more selective ethanol conversion processes.

Recovery of high quality water from human urine using a novel vertical up-flow forward osmosis reactor

Nutrients in human urine are very much diluted which increases the cost of transportation for the direct use or increases the cost of treatment processes for the recovery of nutrients. In this work, a novel Vertical Up-Flow Forward Osmosis (VUF-FO) reactor with pulsating inlets was used for the separation of water and for concentrating nutrients from fresh human urine. The performance was compared with the basic H-shape FO reactor for the water flux, membrane fouling and rejection efficiencies of the constituents. After the three days of the process, only a 10% decrease in water flux was observed for the VUF-FO reactor compared to 50% decrease in the case of H-shape FO reactor. Less membrane fouling was observed in the VUF-FO reactor due to the vertical arrangement with the pulsating inlets compare to H-shape reactor. A simple distillation process without membrane was used for the recovery of water from the diluted draw agent. The combination of FO and distillation showed a 100% rejection of chemical oxygen demand (COD) and biochemical oxygen demand (BOD) in the recovered water. The quality of separated water from the urine was comparable with reverse osmosis (RO) water and satisfied the Indian Standards for drinking water.

Developing fuel sources for a steady-state multi-purpose pellet launching system

Like for any power plant, refuelling will be one key issue in a future fusion reactor. It has to be safe and efficient; due to the operational principle, it also needs to occur in steady state. From previous investigations, it became clear that injection of pellets - mm-size solid bodies produced from frozen fuel – is the only possible and technically realistic solution for this task. Beyond their capability for fuelling, pellets have been found potentially useful as well for other purposes, e.g. to control edge localised modes. Therefore, efforts are required to develop a pellet launching system (PLS) capable to meet all basic reactor requirements.To foster this kind of technology evolution and to enhance the PLS applied at ASDEX Upgrade (AUG), a collaborative investigation between IPP and ORNL has been initiated. This aims to replace the existing pellet source able to deliver to a centrifuge injector up to 130 stored pellets produced in a batch process with repetition rates up to 80 Hz by a steady state source. The new source is based on the ORNL extruder types and capable of delivering either in true steady state or at least from a reservoir with sufficient solid fuel to produce up to 2000 pellets. Experiments extruding ice with different square cross sections showed a maximum throughput of about 300 mm3/s for Protium (H) and 215 mm3/s for Deuterium (D) with a 1.9 mm square cross section. Ice temperatures of 9 K for H and 16 K for D were found to be optimum. For D, extrusion rates correspond to a 1.9 mm pellet delivery rate of about 25 Hz. Doping the ice with up to 2% Neon was achieved at the expense of moderately reduced extrusion speeds. A new scheme has been designed to inject pellets in parallel from multiple sources for further enhancing the delivery rate.

Soft and effective detoxification of a VX simulant in a nylon 3D printed basic flow reactor

A flow reactor was designed, manufactured by 3D printing, and modified to promote the selective ethanolysis of a chemical warfare agent VX surrogate.

An Investigation on Improvements to Ultrasound Reactor Configuration for Extraction of Phytochemicals in Industrial Scale

Industrial attentiveness and demand for natural bioactive compounds are rising continuously, regarding their growing commercial values in nutrition, pharmaceuticals, cosmetics and many other industries. The progress in ultrasound technology has spread the use of ultrasonication on a broad field of application areas, including extraction of bio-materials from plant sources. Ultrasound-assisted extraction is a powerful alternative to conventional techniques, in terms of extracting bio-compounds from variable kinds of matrices, higher efficiency, reduced extraction time, toxic-free operation, lower energy demand, lesser water consumption and better extract quality. Existing research pointed out that the reactor configuration is vital for maximizing the efficacy of extraction process, however basic reactor configurations that were mainly used in the literature may not be feasibly adapted to full-scale industrial applications. In this study, an investigation on possible improvements and modifications to existing reactor designs are discussed, such as detecting the optimum frequency range of ultrasound transmission depending on the material rheology and composition, possible modifications in beam-forming by means of frequency modulation and finally transmitting the waves in combination of different frequencies.

Flow Cell Characterisation: Flow Visualisation, Pressure Drop and Mass Transport at 2D Electrodes in a Rectangular Channel

Aiming to demonstrate the importance and facility of characterising the reaction environment in new commercial laboratory-scale flow cells, fluid flow, pressure drop and space averaged mass transport coefficient were studied in the C-Flow® Lab 5 × 5 cell. A flow-by configuration with smooth, planar electrodes in a rectangular channel was used. Electrolyte mean linear velocities of 2 to 10 cm s−1 past the electrode surface and channel Reynolds numbers of 53 to 265 were considered. The effect of a turbulence promoter next to the working electrode was evaluated. Flow distribution was explored by a qualitative flow visualization study, while the relevance of pressure drop was shown by measurements over the flow channel and the whole cell as a function of mean linear velocity. The electrochemical performance was quantified from the limiting current, permitting the determination of the mass transport coefficient at the electrodes over the same range of flow rates. Reactant conversion in the batch recirculation mode and normalised space velocity were predicted from the electrochemical plug flow reactor design equation. Results were compared to well-characterised electrochemical flow reactors found in the literature. The significance of characterisation techniques and basic reactor models during the development of new processes is emphasised.

Photocatalytic Reactor Design: Guidelines for Kinetic Investigation

This review addresses the inconsistencies in interpreting measurements of intrinsic catalyst properties using lab-scale devices. Any experiment must be analyzed in the framework of a model for which the choice and assumptions regarding the necessary parameters must be based on critical reasoning. Physical intuition about the properties of the system is required for both rigorous 3D computational and simplified analytic descriptions. Any divergence between hypothesis and characteristics of the systems affects both the investigation of intrinsic catalytic properties and the later industrial design where parameters are extrapolated outside their obtained operating range. In this work, we make an overview of the underlying physics of photocatalytic reactions, while focusing on pertinent hypothesis, and discuss the consequences for the most basic reactor designs for which guidelines and criteria are provided to meet their premise.

Simulations of advanced reactor cores in research light water reactor LR-0

A design verification by basic neutronic experiments is an integral part of maturing a reactor concept. Before building a demonstrator unit, it is useful to design and carry out verification and validation work concerning the modeling tools as well as nuclear data in a mock-up simulating the environment in an advanced reactor. The focus of this paper is to show how the experimental research light water reactor LR-0 is used in development work connected to a wide range of advanced reactor concepts: High Temperature Gas Cooled Reactor (HTGR), Molten Salt Reactor (MSR), Molten Salt Fast Reactor (MSFR) Lead Cooled Fast Reactor (LFR), and Gas Cooled Fast Reactor (GFR). Results show that a large channel in a light water research reactor with appropriate neutron filter can be used for studies of basic reactor physics in the fast part of the neutron spectrum of some more advanced systems.

Fundamentals of reactor physics with a view to the (possible) futures of nuclear energy

Abstract This paper present basic nuclear reactor physics that may help to understand next challenges that nuclear industry have to face in the future. The ones considered in this work are waste production and natural resources consumption. This paper shows that waste and resources are linked by the plutonium status that could be considered as the principal waste or a valuable material that should be saved for a future transition to breeder reactors that could be for instance Sodium-cooled Fast Reactors (SFRs). This kind of reactors does not rely on natural resource supply, as it produces its own fissile material, plutonium-239, after a neutron capture on uranium-238. However, the operation of SFRs needs a huge amount of plutonium that should be produced in current Pressurized Water Reactors (PWRs). Natural uranium available on earth is expected to allow the operation of the global current fleet until approximately 2100 without major issues. The transition from PWRs to SFRs is then needed if and only if the nuclear industry will face an increase at a global scale during this century. If not, plutonium, the most radiotoxic element produced in PWRs, should be considered as a waste. Consequently, the plutonium status depends on the future evolution of nuclear energy. This paper shows that a status-quo means that plutonium should be considered as the most problematic element that should be handled on a long-term basis. On the other hand, a strong increase in nuclear energy on a global scale would imply that plutonium is a valuable material that would make a transition to SFRs possible.

Criteria of return on investment in nuclear energy

Analytical relationships between the investment performance criteria (net present value (NPV), levelized cost of electricity (LCOE), internal rate of return (IRR), discounted payback period (TPB), and discounted costs (Z)) and basic engineering-economic parameters of nuclear reactors (capital costs K, annual operating costs Y, annual revenue R, NPP construction TC and operation TE periods), characterizing the NPP profitability and competitiveness at the microeconomic level, are defined for the first time. The power function of discounted cash flows was used in calculations.It is shown that the joint analysis of the entire set of investment efficiency criteria (not only LCOE as it is often done) can help avoid contradictions in assessing the NPP project profitability and formulate optimal requirements on the reactor engineering and economic parameters. The obtained analytical expressions provide solutions not only of the traditional «direct problem» (assessing efficiency criteria according to the forecasted capital and operating costs and profit stream) but, which is of equal importance, the solution of the «inverse problem»: assessing restrictions on capital and operating costs, i.e. identifying «investment corridors», based on the desired values of efficiency criteria.The investment risk assessment results obtained by Monte-Carlo method are presented in order to account for the inherent uncertainties in the forecasts of long-term cash flow during the NPP construction and operation required for assessing the efficiency of investments. The calculation results of probability distributions of the investment efficiency (profitability) criteria are presented for the specified ranges of uncertainties the forecasted cash flow. It is shown that the risk of project unprofitability can be quite high. In order to reduce investment risks, it is necessary to justify the changes in basic reactor parameters (decrease in K, Y, TC and increase in R and TE) and uncertainty ranges in the initial data.

Development of a point-kinetic verification scheme for nuclear reactor applications

In this paper, a new method that can be used for checking the proper implementation of time- or frequency-dependent neutron transport models and for verifying their ability to recover some basic reactor physics properties is proposed. This method makes use of the application of a stationary perturbation to the system at a given frequency and extraction of the point-kinetic component of the system response. Even for strongly heterogeneous systems for which an analytical solution does not exist, the point-kinetic component follows, as a function of frequency, a simple analytical form. The comparison between the extracted point-kinetic component and its expected analytical form provides an opportunity to verify and validate neutron transport solvers. The proposed method is tested on two diffusion-based codes, one working in the time domain and the other working in the frequency domain. As long as the applied perturbation has a non-zero reactivity effect, it is demonstrated that the method can be successfully applied to verify and validate time- or frequency-dependent neutron transport solvers. Although the method is demonstrated in the present paper in a diffusion theory framework, higher order neutron transport methods could be verified based on the same principles.

CO2 Capture by Calcium Looping at Relevant Conditions for Cement Plants: Experimental Testing in a 30 kWth Pilot Plant

Calcium looping technology has a high potential for capturing CO2 in cement plants as the CaO-rich purge from the calciner can be used to replace a sizable fraction of the CaCO3 used as feedstock. Integrating the CaL process into the cement plant requires the carbonator reactor to operate under new conditions (i.e., a higher carbonator CO2 load, a more active sorbent, smaller particle sizes). This work analyzes the impact of some of the new CaL operating conditions on the performance of the carbonator in a retrofitted 30 kWth testing facility as there is little experimental information available nowadays. A wide range of sorbent activities has been tested, including those corresponding to very large makeup flows of limestone that would be characteristic of CaL applications in cement plants. The results have been interpreted using a basic reactor carbonator model that required little modification of previous versions developed for power plants.