Steam Flow Research Articles

Multi-objective optimization of biomass-rich MSW pyrolysis using hybrid multiphase lumped compartment-kinetic model

Abstract Due to fossil fuels depletion, alternate energy sources are of growing interest. Biomass or municipal solid waste is a renewable energy source that can be converted to oils or synthetic gas through pyrolysis or gasification. A better understanding of the mechanism and kinetics of these processes is essential in the design of industrial facilities. In the present work, pyrolysis product components were taken into consideration along with char and oil as lumped parameters in a compartment model, and the kinetic constants for municipal solid waste two-step pyrolysis were identified based on a proposed simplified set of reactions. The experimental data were obtained from the process of two-step pyrolysis using Ni/ZSM-5 catalyst in a laboratory-scale reactor. MATLAB/Simulink software was used to implement the dynamic model and identify the kinetic parameters based on the experimental results. The model was in good agreement with the measured data, having R2 value of 0.974. The validated model was further used to find the optimal parameters of the process in two cases. The collected gas had the highest lower heating value at the operating conditions of 830 °C, steam flow rate of 0.123 mL/h, and it required reduced experimental time, while the highest volumetric H2 percentage was obtained at 941.6 °C temperature and no steam flow rate at similar to original experimental time. According to the multi-objective optimization results, the Pareto front revealed the most advantageous operating point for both heating value and hydrogen content at 774 °C and zero steam flow rate. Graphical abstract

Research on the Law and Mechanism of Condensation in High‐Temperature Steam Pipes

AbstractDesalination is crucial for addressing freshwater shortages, particularly in coastal cities. However, the specific mechanism and kinetics of droplet condensation in pipes remain unclear. This study employs a coupled VOF‐Lee model in Fluent to investigate steam condensation in a straight tube inclined at 10.00°, under constant wall temperature, steam flow rate, and temperature. The research analyzes droplet distribution, contact angle changes, and maximum droplet center pressure. Results show a positive correlation between droplet equivalent diameter and distance from the pipe inlet. As condensation stabilizes, this correlation remains, while the maximum droplet center pressure negatively correlates with droplet size. When the equivalent diameter exceeds 3.50 mm, the maximum center pressure stabilizes at 60.00 Pa. Additionally, droplets with diameters between 1.50 and 3.50 mm maintain a contact angle of 80.00°, reducing downward flow and lowering condensation efficiency. The study further supports droplet jumping and fusion theory. Industrially, enhancing condensation conditions in the early stage can increase the proportion of droplets exceeding 3.5 mm, improving overall condensation efficiency.

Propose Model of Gathering System Optimization on Unit-G4 Geothermal Power Plant

<span lang="EN-AU">The nature of geothermal heat is a decrease in pressure, temperature, and steam flow. Based on Exaquantum observation data, one of the geothermal power plants in West Java experienced a reduced steam supply for the Geothermal Power plant (GPP) Unit-G4, which decreased production capacity. This study aims to analyze the existing conditions and make models and simulations on the optimum Steam Gathering System (SGS) at GPP Unit-G4. The stages in this research are modelling using Aspen Hysys software on the existing conditions of SGS as a basis for finding alternative optimum solutions. The second stage was to design a model and simulation by interconnecting the K-21X production well with the PL-X05 production. Furthermore, the simulation of adding steam by 25%, 50%, 75%, and 100% in the interconnection process was carried out. Existing steam gathering modelling and simulation results show that the deviation between actual steam field parameters is ≤ 2% (can be used as a simulation baseline). The modelling and simulation results of adding steam from the K-21X production well to the PL-X05 production well are optimum at 100% and 75% steam addition. From the simulation, adding 25% and 50% steam cannot be applied because the net power does not reach the unit rate capacity of 60.856 MW.</span>

Technologies increasing the distillation performance

Improving the energy efficiency of distillation columns widely used in various industries is the focus of many researchers. Although conventional state-of-the-art distillation columns are widely used and cost efficient, new technologies can significantly reduce operating costs, the overall cost of a distillation plant and are important for global sustainable development. This article reviews and compares technologies aimed at increasing the energy efficiency of distillation plants, including multi-effect distillation, thermally coupled distillation, and diabatic distillation. Multi-effect distillation allows increasing the number of separation stages, thereby increasing the process efficiency. In thermally coupled distillation, the number of required heat exchangers is reduced through direct contact of steam and liquid flows fed from different columns. In diabatic distillation, controlled heat exchange devices are used to approximate process conditions to phase equilibrium line of the system. The paper also describes some promising developments improving the design of distillation columns, including the dividing-wall column and distillation with intermediate heat exchangers. These technologies have their advantages and can be integrated in industrial processes under certain conditions. This article is aimed at reviewing and comparing the existing common solutions designed to increase the energy efficiency of distillation columns.

Planck’s constant determination from Ferry’s black-body radiation: a straightforward method

Abstract This article presents a simple and straightforward approach for determining Planck’s constant by examining the radiation emitted from a Ferry-like black body configured as a hemisphere. The Ferry black body was maintained at a constant temperature of ∼98.5 °C through the continuous flow of steam within a double-walled structure. The radiation emitted from the inner blackened surface and through a small aperture at the bottom was captured by a sensitive T-type double-junction thermocouple. One junction of the thermocouple was connected to a silver disc to capture the maximum radiations emitted from the aperture, while the other junction was maintained at room temperature in silicon oil. The variation in thermo-electromotive force (E.M.F.) across the double junction was recorded as a thermal sensing signal when the junction attached to the silver disc was exposed to the black body radiation. For calibration of the double junction, the second junction was heated in silicon oil while the silver disc junction was maintained at room temperature, and the thermo-E.M.F. was recorded as a function of temperature, which was measured using a mercury thermometer. The Planck’s constant obtained through this method was approximately 6.9 × 10 − 34 Js, which closely aligns with the standard value of ∼ 6.626 × 10 − 34 Js. The close correspondence between the measured and standard values of Planck’s constant confirms the effectiveness of this method.

A COMPUTATIONAL SCHEME FOR MODELING THE PROCESS OF MULTICOMPONENT MIXTURE FRACTIONATION

From the equations of the component-by-component material balance of the contact stage and the phase equilibrium of the components, a system of linear equations with respect to the concentrations of the components is obtained. The matrix of the system is ribbon, tridiagonal without a pronounced diagonal predominance of elements. The value of the determinant of the matrix of the system is close to zero, we have a weakly conditioned system. The conditionality of the system can be improved somewhat by introducing a fictitious stage for the feed stream, eliminating the mass-heat exchange contact of liquid flows and a pair of adjacent stages. In this case, a strict diagonal predominance of the element is ensured on the step. For a complex distillation column with a side stripping section, the number of rows and columns of the matrix is increased by the number of contact steps of the stripping section. There are also no supra- and sub-diagonal elements in the cube zone of the column - the top of the stripping section. The next feature is the presence of non-zero elements outside the diagonals corresponding to the input of the liquid flow from the column into the stripping section and the output of the steam flow from the stripping section into the column. The quasi-precision of the matrix makes it possible to form a calculation scheme in the form of a single multithreaded column with corresponding connections between the steps. In a multithreaded column, the number of calculated steps is greater than the number of actual contact steps by the amount of the number of fictitious steps. The representation of the column complex in the form of a single multithreaded column contributes to the successful execution of calculations using a sequential iterative point-by-point method.

FFA FW FLOW INFLUENCE AT NPP KRŠKO

The Krško Nuclear Power Plant (NEK) operates based on a Pressurised Water Reactor (PWR), which utilises three loops for heat transfer: primary, secondary, and tertiary. Heat generation occurs in the primary loop; steam production takes place in the secondary loop; and waste heat is discharged in the tertiary loop. During outages, which occur every 18 months, the secondary systems are exposed to the atmosphere, increasing the risk of corrosion. To prevent this, in 2021, the plant used a chemical solution, Film Forming Amine (FFA), which formed a protective hydrophobic layer on the inner surfaces of the pipelines. In March 2021, during the first use of FFA, deviations were observed in the main feedwater (FW) flow measurements. This affected the reactor power calculations, leading to a 0.4–0.5 % reduction in plant output (approximately 4 MWe). The main feedwater flow is a critical parameter for secondary calorimetric calculations, and has the largest impact on error in the event of deviations. The power reduction was confirmed by comparing various process parameters, including changes in the primary loop temperature differences (ΔT), main steam flow (MS), and generator output vs. condenser vacuum. Since the measurement of the main feedwater flow contributes the most to the uncertainty of primary flow and reactor calorimetric calculations, NEK is focused on improving its accuracy. Developing a numerical model in the computer-based programming environment is proposed as part of further research. This model would enable independent calculations of the main feedwater flow, to reduce the impact of the FFA chemicals on the measurement readout and its associated calculations. The model will be based on thermodynamic equations and algorithms for determining the flow with lower uncertainty than the current system. Using this model, correction factors should be obtained to adjust the current venturi meter readings. Ultimately, this approach will ensure better plant management, reduce energy losses, and increase revenues for NEK and its stakeholders.

Algorithm for determining the mass flow rate and dryness of the thermal agent at the wellhead of steam injection wells in specialized software

Background: Determining the mass flow rate and dryness of thermal agent at the wellhead of steam injection wells is a critical process in the operation, optimization and effective control of its injection regulation. In view of the fact that modern steam flow rate determination instruments based on measurement of variable flow of two-phase medium (steam and water), having a methodological error of more than 10%, cannot provide the necessary accuracy and reliability of measurements, there was a need to develop a calculation variant with the use of specialized software that would allow to correctly solve the problem of determining the degree of steam dryness. Aim: Development of an algorithm for calculation of mass flow rate and dryness of thermal agent at the wellhead of steam injection wells of the K field using specialized software. Materials and methods: Two-phase flow of steam and water in wells is a complex process, where it is important to take into account both physical properties of the medium (temperature, pressure, viscosity) and hydraulic characteristics of the system (resistance of pipelines, pressure losses). Mathematical simulation of two-phase flow “steam – water” was performed in a specialized software package by building a ground model and conducting hydraulic calculations. This specialized software complex allowed to build a mathematical model taking into account these parameters, which provides high accuracy and reliability of calculations. Results: An algorithm for calculating the mass flow rate and dryness of the thermal agent at the wellhead of steam injection wells of the K field based on the model of the onshore steam injection system through the use of a specialized software package has been developed. Simulation allows predicting and optimizing the operation of steam injection wells. By changing model parameters (e.g., production mode, coolant parameters), the impact on well performance and system efficiency can be evaluated. Conclusion: To date, it has not been possible to select equipment that allows correct registration of the two-phase flow of steam-heat agent injected into wells, which is typical for the conditions of the K field. The algorithm developed with the help of a specialized software package is applicable in the formation of technical solutions to improve the efficiency of control of steam injection process regulation.

Thermodynamic Evaluation of the Hybrid Combined Cycle Power Plant in the Valley of Mexico

Modern power generation aims to maximize the extraction of thermal energy from fossil fuels to produce electricity. Combined cycle power plants, leaders in efficiency, sometimes require an additional steam generator to compensate for insufficient exhaust gas energy in the heat recovery steam generator (HRSG), leading to hybrid combined cycles. This study presents a comprehensive thermodynamic analysis of the hybrid combined cycle power plant located in the Valley of Mexico, operating under both full-load and partial-load conditions. The investigation begins with an energy analysis evaluating key performance parameters under real operating conditions, including the power generation, heat flow supply, thermal efficiency, fuel consumption rates, steam flow, and specific fuel consumption. Subsequently, the analysis examines the performance of the steam cycle using the β factor, which quantifies the relationship between heat flows in the steam generator and the HRSG, to maintain a constant steam flow. This evaluation aims to determine the potential utilization of exhaust gas residual energy for partial steam flow generation in the steam turbine. The study concludes with an exergy analysis to quantify the internal irreversibility flows within the system components and determine the overall exergy efficiency of the power plant. The results demonstrate that, under 100% load conditions, the enhanced utilization of exhaust gases from the HRSG leads to fuel savings of 33,903.36 tons annually and increases the exergy efficiency of the hybrid combined cycle power plant to 54.08%.

Targeted migration mechanisms of nitrogen-containing pollutants during chemical looping co-gasification of coal and microalgae.

Targeted migration mechanisms of nitrogen-containing pollutants during chemical looping co-gasification of coal and microalgae.

STRENGTH ANALYSIS OF STEAM TURBINE BLADES FOR A NUCLEAR POWER PLANT

The blade is an aerofoil-shaped component of a steam turbine that has a root attached to the rotor. The root is the base of the blade that supports the entire structure and transmits the torque generated by the steam flow to the rotor. The root must be designed in a manner that takes into account its removal during maintenance and positional maintenance on-the-fly during turbine operation. This essentially ensures a safe working environment for the operators and other personnel in the nuclear power plant. Strength analysis of a steam turbine blade is a prerequisite procedure in the steam turbine design process during which the strength and durability of the blades under various operating conditions are evaluated. Such operating conditions include elevated temperatures, intense pressure and high rotational speeds. The purpose of this scientific work is to demonstrate that the blades can withstand such extreme conditions with little or no degradation over time. The adopted methodology involves modeling of the steam turbine blade using SolidWorks, and using the Finite Element Analysis (FEA) software to simulate the mechanical behavior of the associated blade material under various stress and strain conditions. The analysis takes into account factors such as stress distribution and concentration to predict the response of the blade under high pressure steam jets. The results of the analysis are adopted in the optimization of blade design and material selection to ensure safe and efficient blade operation throughout the entire lifespan of the turbine blade. The results are also useful in the identification of potential areas of weakness or failure that can be addressed through design changes and material improvements.

Energy Efficiency, Local Entropy Sources and Exergy Analysis in Measuring Orifice Plates: A Computational Fluid Dynamics Approach

Accurate flow measurement is crucial for energy efficiency in industrial applications. This study investigates entropy generation in measuring orifice plates under high-pressure conditions (80 bar, 400 °C) using computational fluid dynamics (CFD) in OpenFOAM. Two turbulence models, k-ω SST and Spalart–Allmaras, are employed to analyze compressible steam flow and identify local entropy sources. Building on recent findings, this research explores the hypothesis that the discharge coefficient reflects entropy generation. The orifice plate’s abrupt flow contraction and expansion contribute to significant energy dissipation, affecting exergy efficiency. By quantifying entropy sources through numerical simulations, this study provides insights into optimizing flow metering techniques and reducing irreversibilities. The results show a strong correlation between entropy generation and the discharge coefficient, offering a new approach to improving measurement accuracy. This research supports the advancement of energy-efficient flow measurement methods, aligning with sustainable engineering practices.

Experimental Study of Condensation Characteristics on a Vertical Plate Covered with Metal Foam

Metal foam (MF)-coated plate possesses the advantage of big surface area, thus it has great potential for improving the plate condensers' condensation Heat Transfer (HT). In the current research, the pores density influences of Copper Foam (CF) upon a Flat Plate (FP) with (CF) attached have been studied experimentally. And, the CF pore density conceals the utilized plate structure, which ranges from 10 PPI to 20 PPI, and the porosity of 90%. The feature of flow water steam in CF coated plate is presented by using coefficient method of unit mass efficacy. Also, the pore's density influences of CF size, rate of the mass flow of inlet steam water, and rate of the mass flow of cold water upon the HT and Pressure Drop (PD) have been tested and analyzed. The correlations of HT and for a vertical Flat Plate (FP) with fixed CF are determined the curve-fitting of the investigational values. Additionally, the result elucidated that the CF introduction improves the HT despite causing a bigger . A (10 PPI) sized CF reveals a higher performance. It is also observed that the higher pressure of inlet steam, the higher rate of the mass flow of steam and the lower temperature of cold water will result in the increase of the average Heat Transfer Rate (HTR).

Dynamic analysis and optimization design of parallel/cross-feed MED-TVC systems considering fouling characteristics

Dynamic analysis and optimization design of parallel/cross-feed MED-TVC systems considering fouling characteristics

A Numerical Simulation of Steam Explosion in Preflooded Cavity During a Severe Accident Using the STAR-CCM+ Code

The occurrence of a steam explosion resulting from fuel coolant interaction poses a significant threat to the integrity of nuclear power plants when extremely high-temperature molten corium is released into the preflooded reactor cavity. The present study establishes and verifies a computational fluid dynamics (CFD) model by simulating the TROI steam explosion experiment. The suggested model uses the Lagrangian method to simulate particles and adopts a secondary breakup model by which the particles are fragmented based on the critical Weber number. The increased number of fine particles, surface area growth, and the propagation of the explosion pressure wave following the triggering of the steam explosion are effectively simulated with the established model. The formation of steam flow and the subsequent breakup of particles are basically governed by the heat transfer between the corium particles and the cooling fluids. The mass distribution of particle sizes after breakup is obtained by modifying the main terms of the error function, which determines the diameter of child particles to be comparable with experimentally measured distributions. With this modeling, the maximum pressure obtained by the simulation approaches the measured peak pressure. This suggests that the established CFD model is successful in describing the overall thermal-hydraulic phenomena during a steam explosion. In the future, the steam explosion CFD model will be further enhanced to obtain a more sophisticated model to minimize the uncertainty in steam explosion predictions.

Numerical Study of the Effect of Damper Opening Angle and Flue Gas Temperature on Temperature Distribution in Heat Recovery Steam Generator (HRSG)

Abstract Combined Cycle Gas Turbine (CCGT) utilises the hot flue gas from the gas turbine to produce steam in the Heat Recovery Steam Generator (HRSG). The steam from the HRSG is then used to generate electricity in the steam turbine. At PLTGU Tanjung Uncang Batam, the exhaust gas temperature when the damper is open must be below 400°C. However, the turbine gas with an initial load of 5 MW has an exhaust gas temperature of 560°C - 580°C. It is necessary to remove the turbine gas load or Full Speed No Load (FSNL) to reduce the inlet temperature of the turbine gas. The analysis was conducted using Computational Fluid Dynamics (CFD) with ANSYS Fluent 2020 software. The variations used are the diverter damper angle values of 51°, 68°, and 90° combined with inlet temperatures of 400°C and 580°C. HRSG simulation results, velocity, and temperature contours show that the flue gas is not evenly distributed. The turbine flue gas is only spread along 4 - 12 m. Apart from that, from the results of calculations based on operation conditions, at a flue gas temperature of 580°C, the steam flow rate affects the tube wall temperature. Analysis shows that at a steam flow rate of 0.0576 t/h, the tube wall temperature can increase to 541.84°C, which causes the material strength limit to decrease significantly to 143.94 MPa. The ideal steam flow rate is 2.484 t/h, at which the material strength limits remain almost the same as the current operating conditions (400°C). Thus, if the steam flow rate is 2.484 t/h, which is safe for the tube temperature, there is potential for cost savings. Savings from using demineralized water reach IDR 24,708,240 per start up process.

Reduction of spruce phytotoxicity by superheated steam torrefaction and its use in stimulating the growth of ecological bio-products: Lemna minor L

Abstract The use of biochar in agriculture is associated with the concepts of "carbon sink" and "carbon negative," which will constitute additional income for farms in the near future and may provide them with a key role in the fight against global warming. The existing model in the Scandinavian countries is one of the first to combine biochar with carbon dioxide biosequestration. Fertilizers with excessive nutrient content, salinity issues, impurities, or irregular pH levels can induce phytotoxicity, damaging plant health and growth. Torrefied woody biomass can work as a bulking agent, carbon carrier, or as an amendment for composting materials containing high amounts of water and/or nitrogen contents. Superheated steam torrefaction as a valorization process increases the amount of pores in which minerals can be stored and the plant will grow faster and bigger by using these pores agglomerated minerals. The torrefaction process was conducted using the DynTHERM TG Rubotherm high-temperature and high-pressure thermogravimetric analysis apparatus under conditions of superheated steam flow. Various residence times (10, 20, and 40 min) and torrefaction temperatures (250, 275, and 300 °C) were explored to assess their efficacy in reducing the phytotoxicity of torrefied spruce. To confirm this assumption, a toxicity test with Lemna minor L. was carried out according to Radić et al. (2011) and extended to the determination of chlorophyll index and chlorophyll fluorescence to assess the physiological status of the plants after treatment with different doses of spruce wood biocarbon. Research indicates that biochar positively impacts soil quality and plants. Thanks to its unique properties, biochar provides nutrients, enhancing fertilization efficiency [1]. Biochar, after concentrating and adsorbing the nutrients from the wastewater, can be used as a soil amendment or fertilizer. Biochar blended with organic residues full of nutrients is more effective in improving soil properties and crop yields than the exclusive application of pure biochar or other fertilizers. Traditional chemical fertilizers have drawbacks, such as rapid nutrient leaching, severe environmental pollution, and high costs. Therefore, biochar is gaining increasing recognition worldwide.

Tempvision 1000: A Portable Temperature Measurement and Monitoring System for Boiler Combustion

This research investigates the operational and maintenance strategies aimed at improving boiler combustion efficiency at PT Indonesia Power UJP Banten 1 Suralaya, with an emphasis on the integration of the Portable Temperature Measurement System (PTMS) and the Distributed Control System (DCS). The objectives encompass comprehending the workflow of power plant systems, the role of PTMS in monitoring boiler combustion temperatures, maintenance facilitated by PTMS, and tackling challenges such as slagging and temperature deviations. Data were collected through direct observation of PTMS operations and analyzed using Rodin III PTMS software, employing a quantitative methodology. Parameters including Distributed Control System (DCS) data, specific fuel consumption (SFC), coal flow, air flow, steam flow and pressure, superheater (SH) and reheater (RH) temperatures, and air ratio served as benchmarks. Measurements from the boiler layers (TOP, LT8, SOFA, CCOFA, G, EF, CD, and AB) offered insights into the temperature distribution. The findings demonstrate that the integration of PTMS and DCS improves monitoring accuracy, facilitating precise adjustments to enhance combustion efficiency. Adjustments to the secondary air damper minimized temperature variations, addressed slagging problems, and reinstated sighthole functionality, as observed at CCOFA5, facilitating thorough data collection. Regular maintenance of components such as pulverizers and analysis of combustion byproducts ensured uniform fuel distribution and operational reliability. This integrated approach enhances efficiency, decreases emissions, and mitigates environmental impact. This study highlights the significance of advanced monitoring tools and proactive maintenance for sustainable and reliable power generation, providing a framework for analogous systems aiming for improved performance and energy sustainability.

Probing the water adsorption and stability under steam flow of Zr-based metal-organic frameworks using 91Zr solid-state NMR spectroscopy.

The stability of metal-organic frameworks (MOFs) in the presence of water is crucial for a wide range of applications, including the production of freshwater, desiccation, humidity control, heat pumps/chillers and capture and separation of gases. In particular, their stability under steam flow is essential since most industrial streams contain water vapor. Nevertheless, to the best of our knowledge, the stability under steam flow of Zr-based MOFs, which are among the most widely studied MOFs, has not been investigated so far. We explore it herein for three UiO-like Zr-based MOFs built from the same Zr cluster but distinct organic linkers at temperature ranging from 80 to 200 °C. We demonstrate the possibility of acquiring their 91Zr NMR spectra using high magnetic field (18.8 T) and low temperature (140 K) and of interpreting them by comparing experimental data with NMR parameters calculated by DFT. NMR observation of this challenging isotope combined with more conventional techniques, such as N2 adsorption, X-ray diffraction, IR, and 1H and 13C solid-state NMR spectroscopies, provides information not only on the possible collapse of the MOF framework but also on the adsorption of molecules into the pores. We notably show that UiO-66(Zr) and UiO-66-Fum(Zr) built from terephthalate and fumarate linkers, respectively, are stable over 24 h (and even over 7 days for UiO-66(Zr)) under steam flow at all investigated temperatures, whereas UiO-67-NH2 containing a 2-amino-[1,1'-biphenyl]-4,4'-dicarboxylate linker degrades under steam flow at temperatures ranging from 80 to 150 °C but is preserved at 200 °C. The lower stability of UiO-67-NH2 stems from its larger pores and its weaker Zr-O coordination bonds, whereas its preservation at 200 °C results from a more limited condensation of water in the pores.

Design and test of steam-injected continuous scrambled egg device.

Design and test of steam-injected continuous scrambled egg device.