Circulation Rate Research Articles

Evaluation of heat transfer conditions during polydisperse gas–solid flow in an industrial fluidised bed reactor

Knowledge of heat transfer conditions in large-scale circulating fluidised bed reactors plays an essential role in their proper design and optimization of theirs. This work presents an evaluation of the heat transfer conditions taking into account the coordinate height of the furnace chamber and the fluidised bed flow regime in the reactor. Experimental tests used method and measurement technique that provides reliable temperature data. The vertical and horizontal temperature profiles were obtained at different 966MWth fluidised bed reactor operating conditions. Four characteristic areas can be distinguished in the furnace chamber: the bottom region with a high-temperature gradient from 10.6 °C/m to 22.7 °C/m; the dense region with a medium temperature gradient from 4.7 °C/m to 7.3 °C/m; the dilute area with the lowest temperature gradient from 0.7 °C/m to 3.1 °C/m and the exit region with a temperature gradient (4.3 °C ≤ grad T ≤ 9.6 °C) similar to dense region. The horizontal temperature profiles confirmed a core-annular flow structure inside the furnace chamber. At the pressure drop below 5 kPa, the low variation of average temperature (from ±0.7 °C to ±4.2 °C) inside the furnace chamber of the CFB reactor was observed. As a result of fly ash recirculation of 3.86 kg/s, the lowest temperature gradient 0.2 °C/m was achieved in the bottom region of the furnace chamber. In the range of bed material circulation rates of 32 to 68 were registered temperature fluctuations 115 °C. The experimental results also showed the variation of the bed temperature was small and kept at a very low level of ±13 °C whereas the fluidised bed reactor was operated with a fluidisation velocity range of 1.8 to 2.4. Obtained findings provide unique data on heat transfer conditions in industrial facilities and thus fill the gap in literature data for CFB reactors. Based on main tests carried out in a large-scale CFB reactor, it can be concluded that detailed experimental data on thermal conditions provide important information to validate guidelines and for verifying empirical relationships, which are used in the design, optimization, and scaling of heat transfer surfaces in commercial fluidised bed reactors.

Enhanced separation of oil-in-water emulsion by cyclic penetration of emulsion droplets through an oil layer

The separation of emulsion components is a typical heterogeneous phase separation process. This process can be promoted by coalescence of the dispersed phase droplets. However, the coalescence would be inhibited due to the interface between the continuous and dispersed phases. The separation efficiency can be increased by increasing the probability of collisions between the droplets, and this can be realized by increasing the area of contact among the dispersed phase droplets. In this study, a new enhanced separation method involving the circulation of emulsion droplets containing an emulsified oil phase through an oil layer is proposed. The migration of the emulsified oil phase from the millimeter-sized droplets to the oil layer was studied. This migration enabled efficient separation of the oil and water phases, and this process was assessed by using a dyeing agent in the oil phase and by monitoring the variation in the turbidity. The influence of main factors such as the circulating droplet size, thickness of the oil layer, and effect of the circulation rate on the separation was determined. The turbidity of the emulsion reduced from 394.33 NTU to 10.98 NTU, with a separation efficiency of 97.22 % under the optimum operation conditions. The linear fitting relationship for the main factors that affect separation with the duration or number of circulation cycles was obtained. The results indicate that the novel strategy of using an additional oil layer and circulating emulsion droplets through it is promising for oil–water separation, especially via gravity separation.

Research on the lubricating oil leakage characteristics in the vapor compression heat pump system under refrigerant leaking

Refrigerant leakage is a situation that often occurs in refrigeration equipment such as heat pumps. However, certain alternative refrigerants, while exhibiting superior environmental performance, possess varying levels of flammability. The leakage of flammable refrigerants into confined spaces can pose a significant risk of explosion. The amount of lubricant in the leaking refrigerant will undoubtedly affect the flammability characteristics of the refrigerant. In this paper, the content of PVE32 oil in the leaking refrigerant during the operation of a heat pump was investigated. The results showed that, under the five leakage rate scenarios set up in the experiment, the oil concentration was highest when the leakage occurred at the condenser inlet and lowest when the leakage was at the evaporator outlet. During the leakage process of the experiment, as the mass flow rate of the leakage increased, the oil content in the early stage of the leakage increased, but the oil content in the late stage of the leakage decreased. The reasons for the change in oil content were analyzed by the oil circulation rate and the degree of phase separation. The decrease of the oil circulation rate and the change of the degree of phase separation were the key factors affecting the magnitude of the oil content as the leakage proceeded. The results of the study reveal the leakage characteristics of lubricating oil with refrigerant leakage.

Effect of swab and surge pressure on the time-dependent wellbore natural fracture development

Drilling engineers continue to grapple with the persistent challenge of maintaining wellbore stability. Throughout the drilling process, the wellbore pressure experiences fluctuations induced by various factors such as swab and surge pressure, leading to potential instability. This study employs a numerical approach, utilizing Abaqus software, to investigate the impact of swab and surge pressure on the natural fracture growth within the wellbore and the evolving pore pressure. A computational tool developed with MATLAB is then utilized to ascertain a safe operational mud window by assessing the time-dependent collapse and fracture pressures. The findings illustrated a notable increase in fracture width as a function of time in response to swab and surge pressure, with the most significant percentage increase reaching 69.92%. Notably, a 69.16% augmentation in fracture width is observed in the immediate vicinity of the wellbore following the application of swab and surge pressure. However, parameters such as fracture length, loss circulation rate, and pore fluid pressure exhibited marginal changes post-integration of swab and surge effects. The examination of the time-dependent wellbore stability after integration of swab and surge pressure indicated a narrowing of the initial mud window as a function of time, with a 14.33% increase in collapse pressure and a 13.80% decrease in fracture pressure. The numerical model verification against analytical solutions demonstrated good agreement, highlighting its potential utility in optimizing particle size for wellbore reinforcement and mitigating lost circulation through natural fracture sealing.

Research on the generalization issue of the heterogeneous QC-EMMS drag model for gas-solid fluidization

In the circulating fluidized bed (CFB), the non-uniform mesoscale structure formed by the particle clustering effect causes a substantial decrease in the gas-solid drag. Since the degree of particle clustering varies with operating conditions, an accurate drag model needs to be universal in different heterogeneous flow conditions. In this study, the relationships between the Ψ factor in clusters' solid holdup model that characterizes the flow non-uniformity and the operating parameters of CFB (including slip velocity Reynolds number, Re*, bed-averaged solid volume fraction, εs,bed, and solid mass circulation rate, Gs) are established. It improves the adaptability of the QC-EMMS drag model under different working conditions. In previous research, we established two types of models that related Ψ factor to Re* and εs,bed respectively. However, there exists a problem of high dispersion of points, indicating that the selected parameters cannot fully describe the flow non-uniformity. Therefore, Gs is reintroduced to modify the two types of models. The results show that the prediction accuracy of the modified models is improved and the relative error is <10%, indicating that the non-uniform factor Ψ has a strong correlation with Gs. In addition, the quantitative relation between Re*, εs,bed, and Gs is derived from modified models, and the trend of relation is highly consistent with the fluidization diagram proposed by Yerushalmi J., which verifies the accuracy of modified models. Finally, numerical simulation of typical CFB cases proves the adaptability of the modified models in wide operating conditions of fluidization.

Transforming abandoned petroleum wells in the Nigerian sector of the Chad basin into triplet borehole heat exchangers for sustainable power generation

This study pioneers a transformative approach to sustainable energy recovery, repurposing abandoned petroleum wells in the Nigerian Chad Basin as a triplet-deep closed-loop heat exchanger. We employed a computational numerical approach to designed two deep closed loop systems, which share a common production well, and to evaluate the thermal performance as well as its sustainability over a period of 25 years. The geometrical configuration consists of two injection wells, which converge to the common production one doubling the flow rate at surface and minimising the heat loss during the ascent of the fluid. The availability of detailed abandoned well specifications enabled us to constrain three-dimensional geological and thermal models of the undisturbed underground and, subsequently, to simulate numerically the production temperature and the thermal disturbance in the surrounding rocks. A comprehensive sensitivity analysis optimized the best operational design for total recovered thermal energy and uninterrupted heat recovery. When the deep close loop heat system operates with a fluid circulation rate of 0.03 m³s⁻1 and an injection temperature of 20 °C, it sustains a production temperature of over 100 °C, which generates total recovered thermal energy of 9730 TWth and 817 TWe over 25 years (9000 days). The average annual thermal and electricity productions of 389 TWth and 33 TWe, respectively, are more than the demand of the entire population of Magumeri district. The study's findings offer practical implications for policymakers, industry stakeholders, and local communities, emphasising the potential for socio-economic development while fostering environmental stewardship in the Nigerian Chad Basin.

Optimization of Radial Jet drilling for hard formations present in deep geothermal wells

Creating controllable fractures in geothermal wells with deep crystal structures is challenging due to rock strength. Radial Jet Drilling (RJD), which creates micro holes through rock, could stimulate these wells. However, it is challenging to implement RJD when drilling hard magmatic formations that are difficult to jet. Several factors influence RJD's effectiveness, including the jetting bit design, fluid properties, circulation rate, injection pressure, stress state in the formation, borehole pressure, and temperature. These factors determine RJD's performance parameters, such as jet stagnation pressure, jet hydraulic power, and maximum lateral hole length. This study aims to develop a generalized model for optimizing RJD's application in geothermal wells with hard formations. A unique feature of the study is the coupling of a hydraulic model with jetting criteria (threshold conditions) developed for evaluating jet-rock interactions under high-pressure conditions.This study introduces an advanced hydraulic model for RJD application, distinct from classical models that rely on field measurements and typically analyze only horizontally oriented nozzles. Our model encompasses a broader scope of operational and design parameters, facilitating the optimization of RJD in challenging geothermal environments without necessitating direct field data. Key performance metrics such as jet stagnation pressure, jet hydraulic power, and maximum lateral hole length are evaluated, emphasizing the critical role of each in overcoming the inherent challenges of hard rock formations, which require stagnation pressure of more than 100 MPa and jet hydraulic power of more than 5.2 KW. The findings reveal that achieving these conditions requires carefully balancing injection pressure, fluid flow rate, and equipment capabilities. Notably, the model underscores the necessity for robust equipment capable of high-pressure operations, including flexible tubing, compact downhole pressure intensifiers, and more advanced inclination and azimuth detection systems for lateral hole trajectory measurement and control.According to the new model, the RJD technique can be optimized by varying the densities of flexible tubes, the inclination angles of the lateral hole, and the number of back-jetting (BJ) nozzles. Results demonstrate that using an aluminum tube or adjusting the lateral hole to an inclination of 74° can enhance the maximum lateral hole length (MHL) by up to four times for the baseline case. Furthermore, increasing BJ nozzles from four to six can lead to an eightfold improvement in the MHL for the baseline scenario. Overall, the study enhances our understanding of RJD's potential in geothermal well stimulation. It offers a comprehensive framework for effectively implementing it in hard rock settings, creating a scenario for more efficient and economically viable geothermal energy production.

Analysis Study of Available Alternatives for Mitigation of Aromatic Hydrocarbon Emissions from a Glycol Dehydration Unit

A natural gas (NG) dehydration unit based on glycol absorption is considered one of the most important gas processing units, aiming to decrease water content and consequently adjust its dew point. However, during this process, not only water is absorbed by the glycol solvent, but also some aromatic compounds, including benzene, toluene, ethylbenzene, and xylene (BTEX), in addition to volatile organic compounds (VOC), are absorbed. These compounds are released during glycol regeneration into the atmosphere, resulting in environmental pollution and consequent catastrophic mental and physical health problems. This study aims to minimize BTEX emissions while ensuring efficient dew point control. Various strategies have been adopted to control BTEX emissions, but the present work focuses on optimizing operating conditions and investigating the influence of operational variables on BTEX emissions, as well as NG water content. LINGO optimization software and HYSYS (version 11) are used to find the plant’s optimum conditions for minimizing BTEX emissions and satisfying efficient dew point control. Simulation results show that stripping gas, triethylene glycol (TEG) circulation rate, and inlet feed gas temperature significantly affect BTEX emissions. The proposed optimum operating conditions in this work resulted in a reduction in BTEX emissions by about 81% while satisfying the required NG dew point. Furthermore, two quadratic equations are developed based on regression analysis for efficient calculation of the BTEX emissions and water dew point at any operational variables.

Emergency thoracostomy as a safe and effective intervention in prehospital trauma

Traumatic tension pneumothorax is one of the most frequent causes of early mortality among the severely injured. Different methods are recommended for chest decompression. The aim of this study is to examine whether emergency thoracostomy can improve the real 30-day survival compared to the expected Revised Trauma Score (RTS) based survival, the Return of Spontaneous Circulation (ROSC) rate in Traumatic Cardiac Arrest (TCA), reduce the occurrence of tension pneumothorax (tPTX) and to determine the complication rate of the intervention.

A Cold Flow Model of Interconnected Slurry Bubble Columns for Sorption-Enhanced Fischer–Tropsch Synthesis

For technical application with continuous operation of sorption-enhanced (SE) reactions, e.g., Fischer–Tropsch, a special reactor concept is required. SE processes are promising due to the negative effects of water on conversion and catalyst. The reactor concept of two interconnected slurry bubble columns combines the reaction with in situ water removal in the first, and sorbent regeneration in the second column with continuous exchange of slurry between the two. The liquid circulation rate (LCR) between the columns is studied in a cold flow model, measured by an ultrasonic sensor. The effects of different operating and geometric parameters, e.g., superficial gas velocity, liquid level and tube diameter on gas holdup and LCR are discussed and modelled via artificial intelligence methods, i.e., extremely randomized trees and neural networks. It was found that the LCR strongly depends on the gas holdup. The maximum of 4.28 L min−1 was reached with the highest exit, widest tube and highest superficial gas velocity of 0.15 m s−1. The influence of liquid level above the exit was marginal but water quality has to be considered. Both models offer predictions of the LCR with errors &lt; 6%. With an extension of the models, particle circulation can be studied in the future.

Charge-Switchable nanoparticles to enhance tumor penetration and accumulation

Nanoparticle-based drug delivery systems hold potential in chemotherapy, but their limited accumulation in tumor tissues hinders effective drug concentration for combating tumor growth. Hence, altering the physicochemical properties of nanoparticles, particularly their surface charge, can enhance their performance. This study utilized a computational model to explore a nanoparticle drug delivery system capable of dynamically adjusting its surface charge. In the model, nanoparticles in the bloodstream were assigned a neutral or positive charge, which, upon reaching the tumor microenvironment, switched to a neutral or negative charge, and releasing chemotherapy drugs into the extracellular space. Results revealed that circulating nanoparticles with a positive surface charge, despite having a shorter circulation and high clearance rate compared to their neutral counterparts, could accumulate significantly in the tissue due to their high transvascular rate. After extravasation, neutralized surface-charged nanoparticles tended to accumulate only near blood microvessels due to their low diffusion rate, resulting in substantial released drug drainage back into the bloodstream. On the other hand, nanoparticles with a negative surface charge in the tumor’s extracellular space, due to the reduction of nano-bio interactions, were able to penetrate deeper into the tumor, and increasing drug bioavailability by reducing the volume of drained drugs. Furthermore, the analysis suggested that burst drug release yields a higher drug concentration than sustained drug release, however their creation of bioavailability dependent on nanoparticle accumulation in the tissue. The study’s findings demonstrate the potential of this delivery system and offer valuable insights for future research in this area.

Modeling of Fiber Optic Strain Responses to Shear Deformation of Fractures

Identifying distributed strain sensing (DSS) patterns (or signatures), particularly those arising from different hydraulic fracture geometries, has gained significant attention and research effort. Recent works have generated a catalogue of signatures for planar hydraulic fractures in an elastic rock formation. Yet, in numerous cases (e.g., fault motion and some geothermal reservoir stimulation), the main mode of deformation is a shear on a fracture or a network of natural fractures (particularly during low pressure injection/circulation). However, the specific fiber signatures that result from such shear deformation have not been studied. In this study, we use a three-dimensional poroelastic hydraulic fracture simulator to capture the strain signatures resulting from the shear deformation of fractures in various orientations with respect to the monitoring well. Five key cases are examined: one where the fracture strike is perpendicular to the fiber, another with the strike running parallel to the fiber, a third case where the fracture strike is at 45 degrees to the fiber, a fourth case with a strike slip fault perpendicular to the fiber, and a fifth case where fiber is intersecting the fracture. Theoretically and physically meaningful results were obtained in all five cases, which completely differ from the heart-shaped signature of tensile fracture propagation. It was discovered that the strain pattern changes with the shear deformation direction with respect to the fiber. The model is then used to simulate the response of a fracture network at Utah FORGE to injection to assess whether a signature might be expected in response to the planned injection and circulation rates, and, if so, what strain pattern might be expected. The simulation confirms that a strain response can indeed be observed. More importantly, the fiber response that would be detected in the monitoring well would be a combination of strain signatures from dilation and shear deformation of differently oriented natural fractures. The results in this study provide useful insights on the application of fiber to other stimulation and/or circulation scenarios where shear deformation of a fracture or fracture network plays a major role.

ANONIMITAS VISUAL DAN PENEKANAN VERBAL: Tinjauan Semiotika Konten Instagram BNN Cegah Narkoba

The success of the Badan Narkotika Nasional (BNN) in protecting and saving the Indonesian people from stopping illegal drug trafficking in 2021 has exceeded the target set. This can be realized thanks to preventive campaigns, including Instagram social media. This research aims to present the results of a semiotic analysis of visual content uploaded by BNN via the BNN Cegah Narkoba Instagram account (@bnn_cegahnarkoba) from January to June 2022 based on their success in reducing the rate of triggering and illicit circulation of drugs in Indonesia throughout 2021. The method used in this study is the triadic semiotic analysis by Charles Sanders Peirce, who interprets the relationship between objects through DKV elements, DKV principles, and typography in contents with a representamen that produces an interpretant. The results of this research show that the meaning of the BNN Cegah Narkoba’s campaign content tends to display anonymous visual representations of its audience and places more emphasis on preventive verbal messages. Additionally, visual associations to symbols of popular fictional characters are also used so that the range of impact can be even wider. This tendency is carried out based on compliance with media ethics and consideration of the target audience dominated by young people. Keywords: anti-drug campaign, BNN, Peirce’s semiotics

Internal circulation in carrier phase slugs and its influence on the local hydrodynamics in reactive liquid–liquid segmented flow: Visualisation and PIV studies

Local velocity profiles and fluid circulation in liquid–liquid segmented flow significantly influence interphase mass transfer and associated chemical reactions in reduced dimensions. The present study considers a mass transfer-controlled pseudo first order reaction between iodine dissolved in toluene plugs (dispersed phase) and aqueous sodium hydroxide solution (carrier phase). The circulation patterns in the aqueous slugs observed during PIV experiments are correlated with the overall reaction rate. The extent of reaction is identified by decolourisation of the toluene plugs which is a result of iodine depletion. The experiments reveal that an increase in dispersed phase flow rate increases the circulation rate and local velocity within the carrier phase slugs. This is accompanied by propagation of reactant depletion zone from top to bottom within the organic plug and flattening of plug bottom. Nevertheless, the circulation remains axisymmetric with the stagnation region unchanged at r0 ∼ 0.74R.

Compact organ-tissue electrophoresis system (CORES).

Electrophoretic tissue clearing has been a commonly used laboratory method since the early twentieth century. Infrastructure for standard procedures has yet to be formed. In particular, control of the heat produced by electrophoresis, the voltage applied to the electrodes, the resistance, and the speed of liquid circulation create difficulty for researchers. We aimed to develop a compact organ electrophoresis system that enables the researcher to have easy, rapid, and inexpensive working opportunities. The system includes an electronic control unit, a liquid tank, a temperature control unit, and an electrophoresis chamber. The control unit software can keep the system stable by using information on temperature and circulation rate received through the sensors using the feedback principle. Corrosion and particle collection are reduced to a minimum as platinum wires are used for electrophoresis electrodes. A temperature control unit can heat and cool via a liquid tank base. The CORES is an all-in-one, easy-to-use solution for electrophoretic tissue clearing. It assures efficient, rapid, and consistent tissue clearing. The system was stable with 72 h of continuous operation. Patent applications and trial version studies for introducing the system to researchers are still in progress.

Simulation and optimization of a liquified petroleum gas sweetening process using Aspen HYSYS

Liquefied petroleum gas (LPG) is one of the common fossil fuels that can be derived from natural gas or crude oil. In either case, it contains impurities such as H2S and CO2, which should be removed to obtain sweet liquified petroleum gas with a pure concentration of hydrocarbons such as ethane, propane, and butane. The most common method of gas sweetening process is by using amine compounds, which come in various types, each designed for specific and selective removal of acidic gases. In this study, methyldiethanolamine (42 wt.%) was used as a solvent to extract approximately 0.8% of H2S from sour LPG at a temperature of 400C. The objective of this study focuses on simulating and optimizing the LPG sweetening unit using Aspen HYSYS V11 to investigate the different parameters that affect the separation of acidic gases and to achieve high profitability. The number of trays, circulation rates, temperature, mass and molar flow rates, and other parameters were studied to reduce the H2S concentration to 0% in the treated LPG stream. The sweetening process was proposed to produce LPG with high levels of specific preferred specifications such as calorific value and purity, in addition to being environmentally friendly.

Analysis of the magnetohydrodynamic parameters of S-8BM (S-8B) electrolyzers in the modernization of aluminum smelters

The article aims to determine the magnetohydrodynamic parameters of an aluminum electrolyzer in order to compare different types of bus arrangements used in baths with a Soderberg anode. The electrical parameters of the electrolyzer (current distribution across blooms and anode studs) and magnetic field parameters were computed using the Blums V5.07 program (Polyfem, Russia). Data on circulation rates and skew of the metal in the electrolyzer were obtained using the MHD-Valdis program (developed by V. Boyarevich, University of Greenwich, UK). In the course of the studies, mathematical models of the C-8BM (C-8B) electrolyzer with various bus arrangements were built. Three bus arrangements were selected for testing the installation of a bridge designed to close the current distribution in the anode bus arrangement of the electrolyzer. These types of bus arrangements were realized in two variants: with and without a bridge. The obtained circulation rates and skew of the metal were used to evaluate the possibility of modernizing baths with a Soderberg anode without significant capital costs. When using the first type of bus arrangement, the best current distribution was achieved for the blooms with limits of ~757 A (for the variant without a bridge) and ~656 A (for the modernized variant with closed series), as well as for the anode studs having limits of ~1754 A and ~1609 A, respectively. With the use of the third bus arrangement variant, the current distribution was shown to slightly decrease following the installation of a bridge between the anode bus bars. The obtained results suggest that in the modernization of a C-8BM (C-8B) electrolyzer with different types of bus arrangements, current distribution across blooms and anode studs, magnetic field characteristics (By and Bz components), as well as circulation rates and skew of the metal, have no significant impact on the efficiency of this electrolyzer, which contributes to a faster transition to EcoSoderberg bath electrolysis without significant economic costs.

Single well geothermal heating systems: Technical and economic assessment of two widely-used configurations

Benefiting from the closed wellbore space, the single well geothermal heating system (SWGHS) could avoid a large number of environmental problems compared to conventional geothermal systems. Combined with heat pump, this technology is attracting growing interest for the development of district heating based on medium-depth geothermal resources. Efforts of the scientific community and of business operators now focus on the technical optimization and commercial viability of the different SWGHS concepts already available. Here, we numerically investigate the heat extraction performance of a butted- and a vertical-well SWGHS possibly operational in a geothermal prospect area in Xi’an, central China. We addressed the performance of the two systems in terms of outlet temperature, heat production rate, heating area, and economic benefits. Sensitivity analysis suggests that large circulation rates and low inlet temperatures have beneficial effects on both thermal efficiency and economic benefits of the project. Our integrated technical and economic analysis suggests that the butted-well SWGHS configuration is particularly suitable for long-run, large-scale applications, compared to the vertical-well design. This work can provide valuable references for the applications of SWGHS, which is of criterial importance for reaching carbon peaking and carbon neutrality goals.

Research on cross-platform dissemination of rational and irrational information based on a two-layer network

Numerous social media platforms have evolved into fertile grounds for the proliferation of irrational information, expanding the avenues of information dissemination. This paper initially utilized the Weibo and Bilibili social platforms as exemplars and devised a cross-platform two-layer network SEIaIbR-FXYaYbZ dissemination model grounded in classical infectious disease models. Subsequently, this research computed the model equilibrium point, basic reproduction number, and information entropy through dynamic equations. Finally, the model equations were fitted to real cases to determine optimal parameter solutions and conduct simulation analysis. The simulation results reveal that: (i) information entropy values on both platforms are low, with irrational information predominantly influencing public opinion; (ii) concerning various types of information, the augmentation of rational information results in a reduction of irrational information, while the quantity of rational information remains largely unaffected by changes in the quantity of irrational information; (iii) examining different platforms for information dissemination, alterations in the circulation rate and quantity of rational information on the Weibo platform impact the quantity of rational and irrational information on the Bilibili platform, while those changes on the Bilibili platform exert minimal influence on public opinion information on the Weibo platform. The results and corresponding strategies obtained from this study on the cross-platform dissemination of rational and irrational information on Weibo and Bilibili can provide a reference for relevant departments to guide the rational development of online information and enhance the effective management of public opinion in social media platforms.

Fluid Dynamics Investigation in a Cold Flow Model of Internal Recycle Quadruple Fluidized Bed Coal Pyrolyzer

Internal recycle quadruple fluidized bed pyrolyzer (IR-QFBP) consists of a dual fluidized bed pyrolyzer and a dual fluidized bed combustor and is proposed in this work. It is a new kind of efficient fluidized bed with high pyrolysis and energy efficiency. IR-QFBP may attract extensive attention because of its compact structure. Cold hydrodynamic characteristics of IR-QFBP are the bases of modeling and designing for the hot one. To fully understand the hydrodynamic characteristics of IR-QFBP, a cold flow model on a laboratory scale was designed and set up; furthermore, the two-fluid model (TFM) based simulation was also carried out. The pressure profiles, fluidization states, velocity profiles, and circulation rates of a solid powder at different operation conditions in IR-QFBP were investigated. The results showed that the stable internal circulation of solid powder can be achieved in IR-QFBP. And different circulation characteristics can be obtained by adjusting the operating conditions.