Steam Separator Research Articles

Integrated physical safety–cyber security risk assessment based on layers of protection analysis

The extensive application of information technology in process industries has increased production efficiency but has also introduced new risks. Therefore, it is necessary to systematically analyse the risks within factories to ensure the stable operation of their production systems. This study proposes an integrated risk assessment method based on layers of protection analysis (LOPA), which combines physical safety and cyber security analyses to provide comprehensive risk assessments for the process industry. The method first identifies the hazardous scenarios and protection layers relevant to a process facility. It then identifies potential cyberattack types and existing countermeasures. Subsequently, the functional impacts of attacks on protection layers and potential coupling relationships are discussed. Using common vulnerability scoring system (CVSS) and semi-quantitative methods, the probability of attack is determined to optimize the probability of failure on demand (PFD) of the protection layers. Finally, a case study of a steam separator in a catalytic cracking unit is used to quantitatively explore the potential attacks and risks of coupled protection layers. The application of Bayesian network (BN) is used for further validation of the method. This study offers a novel quantitative tool for risk assessment in the process industry, which can enhance the security and reliability of industrial production and control systems.

The concept of creating a maneuverable power plant based on a small modular reactor

Purpose. To develop a maneuverable power plant (MPP) based on the NuScale small modular reactor (SMR) by selecting a thermal scheme structure for a steam turbine installation using minimal additional equipment and ensuring its operation in both nominal and peak modes with maximum efficiency. This also includes ensuring its maneuverability through the use of hydrogen technologies for generating, storing, and returning energy to the steam turbine cycle. Methodology. The study employed the method of mathematical modeling of thermodynamic cycles of thermal schemes of steam turbine installations (STI) with concentrated parameters, which makes it possible to describe the dynamics of systems consisting of discrete elements that are thermodynamic systems. Findings. Various structural options for the thermal scheme of the MPP based on the NuScale SMR for nominal operation were developed and mathematically modeled, followed by a comparative analysis of their energy efficiency. As a result, a scheme and operational parameters were selected with the highest electrical efficiency (net), which allows increasing the net efficiency of the NuScale SMR-based power plant from the developers’ announced 28 to 32.8 %. A thermal scheme for the MPP based on the SMR with an energy storage system was proposed. Applying this scheme allows increasing the net efficiency of a power plant based on NuScale SMR in peak mode to 34.8 %. Originality. A concept for creation and schematic solution for a prospective MPP based on an SMR capable of accumulating electrical energy was proposed. The main innovative solution regarding the structure of the technological scheme of the MPP based on the SMR is the organization of its operation in nominal and peak modes, which fundamentally differ in the thermodynamic cycle. In the nominal mode, the steam turbine installation operates on a thermodynamic cycle with steam separation, and in the peak mode without it, by increasing the temperature of fresh steam as a result of burning hydrogen and oxygen. Hydrogen and oxygen are produced in an electrolyzer during the power plant’s operation in the nominal mode by using the generated electricity “excess”. Practical value. Small modular reactors are currently mainly in the development stage. Additionally, the non-nuclear part of the SMR-based power plant, namely the STI, has not received sufficient attention, as evidenced by the literature. However, it plays a crucial role in the overall efficiency of the installation. The study focuses on the highly relevant issue of improving the efficiency of an SMR-based power plant by developing the structure of the STI thermal scheme involving hydrogen technologies. This will help reduce dependence on fossil hydrocarbons in the total volume of primary fuel and enable sustainable functioning of the Ukrainian energy system, as well as contribute to the preservation and improvement of the environmental state.

Solid Oxide Electrolysis Cell-Based Syngas Production and Tailoring: A Comparative Assessment of Coelectrolysis, Separate Steam, CO2 Electrolysis, and Steam Electrolysis

Solid Oxide Electrolysis Cell-Based Syngas Production and Tailoring: A Comparative Assessment of Coelectrolysis, Separate Steam, CO₂ Electrolysis, and Steam Electrolysis

A Review of the Research Progress and Application of Key Components in the Hydrogen Fuel Cell System

The hydrogen cycle system, one of the main systems used for hydrogen fuel cells, has many advantages. It can improve the efficiency, the water capacity, and the management of thermal fuel cells. It can also enhance the safety of the system. Therefore, it is widely used in hydrogen fuel cell vehicles. We introduce the structure and principles of hydrogen cycle pumps, ejectors, and steam separators and analyze and summarize the advantages of the components, as well as reviewing the latest research progress and industrialization status of hydrogen cycle pumps and ejectors. The technical challenges in hydrogen circulation systems and the development direction of key technologies in the future are discussed. This paper aims to provide a reference for research concerning hydrogen energy storage application technology in hydrogen fuel cell systems.

The Exergy and Energy Analysis of Change Phase Steam in Patuha Geothermal Well Production

A Geothermal Power Plant Company in West Java Indonesia have capacity around 55MW. It company have increased the well production quality to keep up the Indonesia's energy demands. The power plant has been operated around ten years, it has ten geothermal production wells and two injection wells. The either of it wells has an abnormality. It wells has water dominated condition so, the separator equipment is required to separate the steam from water and vapor. Previous study indicated that subsurface water entering the broken reservoir pipe. That leaks in reservoir pipe was repaired in 2020. The impact after the pipe have been repaired it made the fluid characteristic of reservoir be vapor dominated. After that a separator as a steam separator is no longer required. The study compares the value energy and exergy power of the power plant. The calculations are performed from the well reservoir and all power plant equipment. According to the results of the energy study, the plant's energy efficiency after the transformation increased by 0.03%, from 19.48% to 19.52%. The exergy value of the brine in either wells (separated steam cycle) is also known to be 2.512,52 kW, beyond which the value will become zero.

Experimental investigation on the separation characteristics of the novel combined separator

The cyclone separator is widely used as the efficient steam separation device for the nuclear reactor. In this study, a novel gas–liquid separator that can realize efficient and stable gas–liquid separation under a wide range of working conditions is designed. The separator is organically combined with an axial cyclone separator and a tangential cyclone separator. The axial cyclone separator performs the role of rectification and pre-separation, and the tangential cyclone separator ensures separation performance. The variation in the gas–liquid interface characteristics and separation characteristics of cyclone separation under different inlet flow rates are investigated. Compared with the single tangential cyclone separator, the separation deterioration range of the novel separator is significantly reduced. The addition of the pre-separator effectively broadens the operating conditions for efficient separation. The pressure drop of the novel separator is reduced by more than 50 %. Based on the separated flow model, the relationship between the separation pressure drop ratio and dimensionless number is established, and the prediction method for the pressure drop is put forward with the prediction accuracy within ±10 %, which provides reference for the practical application of the novel separator.

Three-dimensional Euler grid approximation method for multi-droplet motions in the steam-water separator

Motions of multi-droplets in steam flow are a common and important phenomenon in various fields such as the environment, chemical industry, and energy. To simulate the motion of multiple droplets, a three-dimensional Euler grid approximation method, which applies to structured and unstructured grids, was proposed. Criteria were established to ensure that the motion of droplets is restricted to the grid nodes without compromising accuracy. The method is capable of updating the information of multiple droplets at each calculation step for all nodes and obtaining distribution information including droplet density and velocity. The multi-droplet motions in the steam separator were simulated and velocity field of multi-droplets showed a symmetrical distribution. The multi-droplet motions process in the swirl vane separator of the steam-water separator was also simulated. The results demonstrated that under the studied operating conditions, the critical droplet radius that can be separated by the steam-water separator was 40 μm. The specific positions of droplet-wall collisions were mainly concentrated on the blades and outer wall of the swirl-vane separator, as well as the inner cylinder. The model may serve as a dependable guide for the optimal solution of separation device structures and simulating various other multi-droplet motion processes.

CO2 capture using steam ejector condenser under electro hydrodynamic actuator with non-condensable gas and cyclone separator: A numerical study

The concept for condensation of steam and CO2 separation in a negative CO2 emission gas power plant involves the utilization of a steam ejector condenser (SEC) for direct-contact condensation of vapor with inert gas (CO2) on a spray of subcooled liquid, integrated with a separator to produce pure CO2. Due to the increasing diffusion resistance and reduced convective heat transfer between the steam and subcooled water phases in the presence of non-condensable gas (CO2), the study utilized an electrohydrodynamic (EHD) actuator to enhance heat transfer rate in the SEC. To optimize CO2 purification, the effect of single, dual and quadruple inlets on separation efficiency was analysed. In the SEC, the Eulerian-Eulerian multiphase model is employed, treating water as the continuous phase and the compressible gas mixture (steam and CO2) as the dispersed phase. The standard k-ε model is chosen to depict the turbulence in the ejector. The separator is transient, turbulent, and three-dimensional, using the control volume method. The RSM turbulent model and mixture model are utilized to simulate the turbulent two-phase flow in the gas–liquid separator. The findings indicated that when the mass flux of steam and voltage are increased, the condensation heat transfer coefficient also increases. For a mass flux of steam of 51 (kgm2.s), the condensation heat transfer coefficients were measured to be 0.98, 1.029, 1.08, and 1.134 (MWm2.K) at electrode voltages of 0, 20, 25, and 30 kV, respectively. In addition, a single-inlet cyclone attains a separation efficiency of 95.1 %, while incorporating two inlets improves the performance to 97.9 %. However, the most remarkable outcome is witnessed in cyclones with four inlets, where an impressive separation efficiency of 99.9 % is achieved.

Comparison of mathematical models of steam methane reforming process for the needs of fuel cells

The article presents a comparison of mathematical models of steam methane reforming. The analysis is divided into two parts. The first concerns the reforming process using separate steam reformers. The second part of the article compares models of steam methane reforming processes directly inside fuel cells. Due to the fact that the steam reforming process takes place at very high temperatures, internal steam reforming can only be carried out in high temperature fuel cells. Therefore, the second part of the article deals with molten carbonate fuel cells and solid oxide fuel cells powered by methane. In the case of both of fuel cells, the methane steam reforming may take place directly on the anodes of these electrochemical devices. The mathematical models (for both external and internal reforming) were compared based on available experimental data. In this analysis of mathematical models, particular attention was paid to the causes of discrepancies between the mathematical models and the experimental data. The steam reforming process is influenced by a number of different parameters such as: temperature, ratio of the amount of water vapor to carbon contained in the fuel (steam to carbon ratio), reaction time, presence of a catalyst, type of catalyst and many others. The models presented in this article were also compared in terms of taking into account various parameters that may affect the process of steam reforming. An attempt was also made to assess the accuracy of mathematical models. Unfortunately, for most of the equations considered in this article, numerical values for inaccuracies are not given or described as acceptable or minor.

Cohesive/Adhesive strengths of CsOH-chemisorbed SS304 surfaces

ABSTRACT During the Fukushima Daiichi Nuclear Power Plant (1F) accident, volatile radioactive fission products (FPs) such as Cs-137 were released, which significantly influenced mid- to long-term decommissioning strategies. A substantial amount of the remaining cesium in the pressure vessel may have deposited onto the 304 stainless steel (SS304) steam separators and dryers. This deposited cesium presents a safety hazard during 1F’s decommissioning, as it can generate radioactive dust and complicate waste storage. However, the cohesive and adhesive strengths of CsOH-chemisorbed oxide scales, crucial for understanding the release of cesium-bearing particles from SS304 surfaces, remain undefined. In this study, we explore how CsOH chemisorption affects the cohesive and adhesive strengths between oxide scales and SS304 substrates using a scratch tester. Our tests revealed that cracks formed at approximately the same load, but the overall cohesive strength of the oxide scales decreased following CsOH chemisorption. Furthermore, the transition from cracks to bulk separation occurred more rapidly in CsOH-chemisorbed SS304 substrates, especially those with lower silicon content. Finally, we found that adhesive failure could not be achieved even at 70 N, suggesting that the deposited cesium cannot be completely removed from SS304 during the decommissioning of 1F.

Two-dimensional Euler grid approximation method for multi-droplet motions

Multi-droplet motion in gas flow is a significant two-phase flow in nuclear power plant, chemical industry and environmental engineering. In contrast to droplet generation and collision in microscopic view, multi-droplet motion presents both macroscopic interaction with gas flow and microscopic single droplet motion characteristic. To simulate the multi-droplet motion, we presented the Euler grid approximation method to update the multi-droplet imformation in all nodes under each calculation step, and constructed a criterion about droplet velocity and direction to ensure droplet motion limited on grid nodes without loss of accuracy. The novelty of this method lies in its description of the virtual streamlines of multiple particles in the same state, as well as the discontinuous flow field composed of these virtual streamlines, furthermore, this method is independent of the time step and can simultaneously calculate droplet information of the entire field. Meanwhile, this paper focuses on the two-phase gas-liquid flow in the gravity separation space of the rotary vane separator, and the motion behavior of multiple droplets in the flow field is simulated based on the parameters of the actual steam-water separator.The result shows that the droplets tend to gather towards the center of the main stream, which is the focus area for droplet separation, and the position with higher density may be the point where the droplets collide. The model can be adopted to calculate the separation efficiency in the process of multi-droplet motion in the gravity separation space, rotary vane separator and other steam separation devices, and the results will help guide the optimal design of the separation device structure.

Environmental-friendly regenerated lignocellulose functionalized cotton fabric to prepare multi-functional degradable membrane for efficient oil–water separation and solar seawater desalination

Freshwater pollution and shortage have become an imminent problem. Therefore, it is necessary to develop a multi-functional membrane for the production of fresh water. In this work, the regenerated lignocellulose modified cotton fabric was developed as a novel, multi-functional and degradable membrane (LCPT@CF) for efficient oil–water separation and solar steam generation for the first time. The fabrication method has the merits of simple, environmentally friendly and cost effective. The regenerated lignocellulose was adhered on the surface of cotton fabric by tannic acid and polyvinyl alcohol complexes tightly, and the multilayered structures of the LCPT@CF can be formed, which endowed the membranes with underwater superoleophobic property and durability. The underwater superoleophobic property enabled LCPT@CF to purify various kinds of oil-in-water emulsions with a separation efficiency of more than 99.90%. Moreover, benefiting from the excellent photothermal conversion capacity of regenerated lignocellulose, the LCPT@CF achieved high evaporation rate of 1.39 kg m−2 h−1 and favorable evaporation efficiency of 84% under 1 sun illumination, and the LCPT@CF also presented excellent salt-resistance for evaporating seawater for 20 cycles, without salt accumulation. More importantly, the LCPT@CF could be naturally degradable by microorganisms in the natural condition within 3 months, which had outstanding environmental friendliness. These above results demonstrated that the green and efficient LCPT@CF could play great potential in oil–water separation and sewage purification.

Characteristics of hydrogen separation and methane steam reforming in a Pd-based membrane reactor of shell and tube design

This work investigates numerically the characteristics of the two process, hydrogen separation and steam methane reforming (SMR), in a palladium-based (Inconel-supported Pd–Ag film) membrane reactor (MR) of porous reformer (30% Ni/Al2O3) shell and multi-tube design. Still parameters like reactor design and temperature, feed gas concentration and pressure, and flow configuration need more investigation to figure out their impact on hydrogen production rate at lower energy cost and minimum possible volume. This work targets optimization of reactor performance for higher hydrogen yield and coming up with a scalable optimized reactor design for industrial applications. First, an optimization study is performed under non-reforming (separation-only) conditions to optimize the MR design and operating parameters for higher hydrogen production. Then, the study is extended to consider hydrogen separation under SMR conditions to come up with a MR design for hydrogen production at the industrial scale. Hydrogen permeation is limited to small zone near the membrane surface with no effect of feed pressure, inlet gas temperature, and feed hydrogen concentration on widening such zone that necessitates reducing the pitch distance between membrane tubes below 22 mm. The results showed reduced hydrogen permeation rate under SMR conditions compared to the separation-only cases.

Operating Modes Optimization for the Boiler Units of Industrial Steam Plants

The free market forces energy-intensive industrial enterprises to continuously compete. A possible competitive advantage for such enterprises is reducing the finished products cost. This may be achieved by reducing the share of energy in this cost, including by rationalizing the use of energy resources. This study develops a system for the automated analysis and calculation of feasible boiler unit loads, defined according to the criterion of the minimum cost of live steam in a separate steam plant pipeline. The calculations consider the balance limit on the steam, the boiler unit’s wear and tear, performance specifications, and economic indicators of fuel consumption in the calculation. The software also defines the optimal fuel mix composition when forecasting the operating modes of the power plant boiler units in real-time mode. The calculation algorithm is based on the dynamic programming technique combined with the sequential equivalenting method, which ensures the convergence of calculations. When a steam plant model is developed, much attention is paid to the thermal scheme and technical and economic specifications of boiler units. In the system, the boiler models are set as a table containing the ratio between the boiler unit’s steam capacity and energy consumption while considering the cost of a ton of live steam with the specified parameters. The key economic effect of implementing the system is determined by reducing the fuel cost due to its rational redistribution between the power plant boiler units. Implementing the system allows the reduction of energy costs by 1.4%.

Study on gravity separation of air-water from the upper part of UTSG full-scale swirl separator in pressurized water reactor

The steam separator is one of the most critical components in the U-tube steam generator (UTSG), which qualifies moisture carryover less than 0.1% to minimize the damage to turbines. Take both high separation efficiency and low manufacture cost into account, the height of the gravity separation space should be designed appropriately. Air-water separation experiments are carried out to study the effect of several different gravity heights on the separation performance. A droplet mathematical model is proposed and the experimental results are discussed based on it. The analysis indicated that (1) For Stokes flow, weather initial droplet velocity ud0 is bigger or smaller than vapor velocity ug, the analytical solution of the maximum height h for the droplet to reach can be calculated by the same formula. (2) From the numerical solutions of droplet mechanics model, it is found that separation height is related with all three factors (ug,ud0,D) for the small droplet, but is only related with ud for the big droplet. (3) Experimental results show that there exists a minimum gravity separation height to obtain the maximum separation efficiency under the given gas–water conditions. (4) Initial droplet velocity is the key parameter required for the engineering design of separation space height.

Design of gas-liquid two-phase separation device with application in solar hydrogen production system

Currently, solar thermochemical energy conversion technology has attracted more and more attention because of the increasing global need for clean fuel and chemical energy demand. The thermochemical hydrogen production technology uses solar radiation with concentrated high-density as a high-temperature heat source to produce hydrogen by decomposing water through two-step cycle redox reactions. It is an environment-friendly technology based on artificial photosynthesis utilizing water vapor as the reaction gas. However, limited by the separation efficiency, current gas-liquid separation devices cannot output stable high-purity water vapor and sophisticate the experimental processes. In this research, intensive numerical investigations were carried out on the widely-used corrugated plate steam separators. The structural parameters are designed by the multi-objective optimization method combining the artificial neural network and the genetic algorithm. Nine optimized structures are designed by adding hydrophobic hooks, streamlined, and reducing the plate distance optimization methods. The results give engineering application conditions of different optimized separators. The streamlined single-hook corrugated plate separator with rounded corners exhibited the best separation efficiency under the heat state condition, which is 97.27%. It can also completely separate droplets over 28.5 μm. The applicability of the cyclone steam separators indicated that it is more suitable for pretreatment. The benchmark experimental system was built for the measurement of the separation efficiency resulting in only a 0.73% error. The designed steam separator was successfully applied to the solar thermochemical hydrogen production experiment, which ensures its practicability and pertinence in the process of solar fuel synthesis.

A melanin-inspired robust aerogel for multifunctional water remediation.

Solar-driven vapor generation has emerged as a promising wastewater remediation technology for clean water production. However, the complicated and diversified contaminants in wastewater still restrict its practical applications. Herein, inspired by the melanin in nature, a robust aerogel was facilely fabricated for multifunctional water remediation via a one-pot condensation copolymerization of 5,6-dihydroxyindole and formaldehyde. Benefiting from the superhydrophilicity, underwater superoleophobicity, and synergistic coordination effects, the resulting aerogel not only showed excellent performances in underwater oil resistance and oil-water separation ability, but also removed organic dyes and heavy metal ions contaminants in wastewater simultaneously. Moreover, owing to its admirable light harvesting capacity and porous microstructure for fast water transportation, the aerogel-based evaporator exhibited an excellent evaporation rate of 1.42 kg m-2 h-1 with a 91% evaporation efficiency under 1 sun illumination, which can be reused for long-term water evaporation. Note that such a stable evaporation rate could be maintained even in wastewater containing complex multicomponent contaminants. Outdoor evaporation experiments for lotus pond wastewater under natural sunlight also proved its great potential in practical applications. All those promising features of this all-in-one melanin-inspired aerogel may provide new strategies for the development of robust photothermal devices for multifunctional solar-driven water remediation.

Energy-efficient vacuum evaporation units for concentration in the dairy industry

The application of various types of evaporation plants for concentration of solutions was analyzed. It was noted that the most promising for thickening dairy products are film-type vacuum-evaporation units with mechanical compression of secondary steam. The heating chamber of the evaporator is made in the form of a vertical shell-and-tube heat exchanger with the supply of heating steam into the intertube space and with the downward movement of product solutions in the vertical boiling tubes. Based on the analysis of known studies on hydrodynamics and heat exchange of film processes (condensation, film heating and evaporation and steam separation), a conclusion was made about the lack of data for calculating pressure losses in the steam circuit of the evaporator with sufficient accuracy. To solve this problem, improved methods of calculating the hydraulic resistance of the intertube steam path of the heating chamber and the two-phase flow of the product film and secondary steam in evaporative boiling tubes have been developed using the published results of hydrodynamic resistance research. Pressure losses for the movement of secondary steam in the lower chamber of the evaporator include losses for acceleration of the steam released from the falling film of the product. It is shown that the hydraulic depression of the movement of steam in the intertube space of the heating chamber, depending on the type of scheme, can be from 2.3% to 77% compared to the working temperature pressure of the heating surfaces. The four-way flow scheme of the heating steam used in the design of the vacuum-evaporation unit ensures a reduction of hydraulic losses by up to 15%. A technical and economic analysis of the costs of operating a vacuum-evaporation unit with a productivity of 10 t/h of vaporized steam was performed, according to which the lowest reduced costs were established at a temperature drop of 5˚C on the compressor. The results of the research were used in the development of structures and the manufacture of vacuum-evaporation units with mechanical and mixed (mechanical and thermal) compression at PrJSC "Kalyniv Machine-Building Plant" (Kalynivka, Vinnytsia Region). 10 vacuum evaporation units with a capacity of 5 to 20 t/h of evaporated moisture were manufactured and put into operation.

Sequential Modeling of Paper Drying Process to Reduce Thermal Energy Use, Part 2: Simulation Results

Paper drying is one of the unit operations that consumes the most amount of thermal energy in a papermaking machine. In this paper, a theoretical model for paper drying process was developed using the sequential modeling method based on the conservation laws of mass and energy. Aimed at simulating thermal energy flow, the overall framework of the drying model was constructed according to the specific drying process of a newsprint machine. It was composed of eight basic modules based on their different functions in the paper drying process, i.e., cylinder group module, steam separation module, surface condensation module, fan module, heat recovery module, air heating module, paper sheet module, and hood module. The results showed that it could be used to simulate the material and energy flow of each module, as well as the whole drying process in a more comprehensive manner with integrated thermal energy use and drying performance information. In addition, the effects of operating parameters, such as supply air temperature and exhaust air humidity, on thermal energy use in the newsprint drying process were also simulated. This work also demonstrates that the sequential modeling method is instructive to reduce thermal energy use for the industrial paper drying process.

Optimization investigation on the distribution of both inlets and outlets for the shell of a novel separated structure steam generator

The distribution of both inlets (downcomers for the steam generator) and outlets (risers for the steam generator) for the shell has an important influence on the overall thermal hydraulic performance of a novel separated structure steam generator (SS-SG). Nevertheless, there is no basis for reference in the design process so far. In this article the effect of both the inlets and outlets distribution on the vapor-liquid two-phase flow and heat transfer characteristics was studied and optimized with the help of experiment, numerical simulation and machine learning algorithm. The surrogate model was constructed by the backpropagation neural network based on the genetic algorithm (GA-BPNN). The average boiling heat transfer coefficient (HTC) was selected as the objective function to characterize the rationality of the flow field in the shell. To get the optimal distribution, the global optimization was performed by the genetic algorithm (GA). For the optimal structure obtained, the longitudinal flow was enhanced greatly compared to the original structure. This is beneficial to avoid the local flow stagnation and eliminate the enrichment of ion concentration for long-term operation. Meanwhile, the vapor accumulation at the top of the shell near the front tube-sheet has also been alleviated to some extent. It is beneficial to alleviate the thermal damage of the high heat flux due to heat transfer deterioration. Besides, the average pressure drop was only increased by 0.96%. The results of this investigation are of significance as a reference in the actual design of the novel SS-SG.