Walking Beam Research Articles

Slab assignment to non-identical reheat furnaces running in parallel mode

This article analyses a slab assignment problem for non-identical reheat furnaces in the steelmaking industry. We tackle the problem of assigning slabs to different types of reheat furnaces, a walking beam and a pusher type furnace. Furthermore, we need to determine the feed-in as well as the residence time for each slab. The aim is to (i) reduce the energy consumption, (ii) increase the production rate and (iii) the heating quality of the slabs which depends on the assigned furnace and to what extent the slabs are overheated. Moreover, the subsequent production stage (Hot Rolling Mill), needs to be synchronized with the furnaces which is essential for a smooth production. We specify the problem as a mixed integer optimization formulation that is solved with iterative parameter adjustment. Rapid convergence leads to a novel two-phase solution method that yields furnace schedules that are optimal for the adjusted parameter values in reasonable time. The results show that our proposed method performs better than an industry benchmark by increasing the production rate and increasing the reheating quality. Furthermore, the new generic problem formulation allows using standard software and can be applied to identical or non-identical furnaces highlighting its broad applicability across steel-making companies.

Failure Analysis of Skid Beam in Walking Beam Reheating Furnace of Hot Strip Mill

Failure Analysis of Skid Beam in Walking Beam Reheating Furnace of Hot Strip Mill

Investigation of the heating characteristics of turbulent non-premixed gas combustion in the industrial-scale walking beam type reheating furnace

Oxygen-enriched combustion is widely used in industrial furnaces. To elucidate the multi-physics properties of reheating process, this study numerically explores the flow and combustion characteristics of syngas oxygen enrichment combustion in an industrial-scale walking beam type reheating furnace. The findings demonstrate that gas flow patterns at the furnace inlet primarily encompass the billet periphery, enhancing heat transfer efficiency. Oxygen-enriched combustion achieves lower temperature differences, higher heating temperature and CO2 emissions. Additionally, increasing levels of oxygen enrichment correlates with elevated temperatures, though the increments diminish progressively. Specifically, temperatures at the outlet of the preheating section range from 1100 K to 1200 K, with the middle region of the heating section displaying slightly lower temperatures compared to the areas adjacent to the burner. High temperature zones are primarily concentrated around the burners in soaking and heating sections. In terms of heating temperature and thermal uniformity, 30 % oxygen-enriched condition yields superior performance, evidenced by higher heating temperatures and reduced temperature differentials. Moreover, oxygen-enriched combustion enlarges CO2 emissions, with a 124.5 % enhancement observed. The lowest NO emission content at the outlet occurs during combustion with 21 vol% air and 45 vol% oxygen enrichment, however, these values remain relatively high. The insights derived from this study provide a foundational framework and guiding principles for furnace design and optimization of multi-gradient oxy-enriched combustion.

Energy optimization of a steel slab reheating furnace through the use of swirl and diffusion burners using a new mathematical simulation methodology

This study proposed a new methodology to optimize the fuel use in a walking beam reheating furnace that uses swirl burners in the soaking zone through mathematical simulation. Likewise, the radiative effect of the WSGGM model over the heating and thermal gradient of the slab was analyzed, as well as its thermal implications of using swirl and diffusion burners. The model was validated with experimental temperatures obtained inside the furnace by using 16 thermocouples, and they were compared with those in the simulation, reaching an average error of 3.19%. This methodology has allowed the proposal of new operating conditions in fuel management, making the combustion process more efficient with an average saving of 5,067,360 kg of methane annually, representing 9% of the plant’s current use. This optimization process would mean substantial economic savings for the industry and would also be reflected in a significant decrease of greenhouse gases with adverse effects on the planet.

Mathematical modeling of slab heating in a furnace with walking beams due to their curvature

Slab heating before hot rolling process is necessary for obtaining required metal ductility. The most effective for this purpose are furnaces with walking beams that provide heat supply to all sides of the slab. However, the places of slabs lower surfaces, contacting with water-cooled beams, are shielded from the radiation of the furnace lower heating zones and take the heat from the beams. Previously, the authors developed and programmatically implemented a mathematical model of slab heating in a furnace with walking beams, based on the numerical solution by finite difference method of the three-dimensional heat conduction problem with piecewise defined boundary conditions on the slab bottom surface. In this model, for the open zones of the slab bottom surface, boundary conditions were similar to those on the top surface, and for the zones of contact with the beams were set effective boundary conditions assuming duration of this contact. In this paper, the model was modified to take into account the curvature of the beams and to recalculate the configuration of zones with different boundary conditions on the slab bottom surface for each position of the slab along the furnace. By variant calculations at different values of heat transfer intensity from the slab bottom surfaces to the beams it was determined that curvature of a single beam can significantly change the characteristic of the corresponding “cold” spot, but it practically does not affect the general characteristic of the slab heating non-uniformity. If all fixed beams are subjected to curvature, the final drop across the slab is significantly reduced due to an increase in its minimum temperature. It was found that the influence of beam curvature on the temperature field at the end of heating process is higher the more intensive the heat transfer to the beams is.

Analysis of heat transfer coefficient and skid marks in a slab reheating furnace considering beam misalignment and contact heat conduction

Accurate analysis of slab heat transfer characteristics is crucial for optimal control of reheating furnaces. This paper established a half furnace model to describe the heat and mass transfer and slab step heating processes in a walking beam reheating furnace. The contact heat conduction and beams misalignment are fully considered. The distribution of total heat transfer coefficient and the effect of stepping strategies on skid mark severity are investigated. The results show that the contact thermal resistance accounts for 1/8 of the conductivity thermal resistance of skid buttons and welding pads and has a lighter effect on the skid marks. The misalignment of the water-cooled beams effectively eliminated the original skid marks and minimized the range of the new ones, but the new skid mark severity before discharge from the furnace remains at 121 °C. The total heat transfer coefficient showed a wave distribution on the slab bottom surface and varied in the range of about −0.72 to 1.71 due to the beam shielding. On the slab top surface, it followed a stepped distribution. Stepping while advancing in soaking zone effectively improve the new skid mark temperature and reduce the skid mark severity by 24 °C. Increasing the stepping number can also reduce the influence of skid marks on the temperature of slab end, thus improving the temperature uniformity of the slab head and tail.

Analysis of billet temperature non-uniformity in a regenerative reheating furnace: Considering periodic combustion switching and misalignment contact of walking beams

Improving the billet temperature uniformity is crucial for the quality of rolled products. This paper investigated the heat and mass transfer processes in a regenerative reheating furnace by establishing typical heating unit models. The periodic combustion switching and misaligned water-cooled beams were considered. The effects of furnace temperature oscillation and skid marks on the total heat transfer coefficient distribution and billet temperature uniformity were analyzed. The results indicate that during the heating process of the billet, the periodic variation amplitude of furnace temperature decreases from 86 to 25 °C, and the depth of influence on the billet temperature is about 0.03 m. The total heat transfer coefficient on the billet bottom surface shows a wave distribution affected by beams shielding, but on the top surface, the closer it is to the furnace wall, the smaller the total heat transfer coefficient. The misalignment of water-cooled beams effectively eliminates the original skid mark and reduces the range of new skid mark. However, the cross-sectional temperature difference at the new skid marks remain at about 97 °C. Compared to extending the residence time, increasing the furnace temperature in the soaking zone is the optimal measure to reduce the influence of skid marks.

Design and Analysis of Harmonic Drive Reduction Pump Jack for Dynamic Performance in Oil Extraction

The purpose of this study is to provide a high gear ratio reducing pump jack system, utilizing the characteristics of high transmission ratio and precision of harmonic drives, in order to improve the efficiency of low-permeability oil field extraction. A comparison was made between the new system and the conventional walking beam pump jack. The results showed that at a stroke length of 1.5 m and pumping frequencies of 4.5 min-1, 3.5 min-1, 2.5 min-1, 1.5 min-1, and 0.5 min-1, the maximum acceleration of the suspended load in the harmonic reducing pump jack was reduced by 20.79% compared to the conventional walking beam pump jack.

Artificial Lift: 25 Years of Change Tracked in the Pages of JPT

Nodding donkeys. Thirsty birds. Rocking horses. All are playful nicknames for the oil and gas icon known as a pumpjack. To the uninformed, the pumpjack is a thing-a-ma-jig that has something to do with oil, probably “fracking” because that’s what drilling rigs do, right? But as an industry-educated and well-informed reader of JPT, you know this is inaccurate. By whatever name you call it, you know that the pumpjack is the visible manifestation of an invisible physics equation, a mechanism buried deep underground that lifts reservoir fluids to the surface. You also know it is one type of artificial lift available in a stable of systems with equally curious and technical names like progressive cavity, plunger, jet, gas lift, and electrical submersible pump (ESP). While there is no global repository of artificial lift statistics, industry observers estimate that 90 to 95% of the world’s producing wells use artificial lift, as noted in a 2013 JPT story on the challenges and opportunities for artificial lift. Artificial lift, as applied in oil and gas production, has existed for over 100 years. A 2014 JPT story laid out a brief history of the practice, sharing how the walking beam principle dates back to at least 476 CE when used in Egypt, and evidence of the use of sucker rods to lift fluids has been excavated from the homes of wealthier families in the early days of the Roman Empire. Even as we leap forward to the modern-day application of artificial lift systems, many techniques and technologies resemble their original designs. How these systems are applied has changed, especially in the past decade-plus with the emergence of shale. As highlighted in a JPT story on the past 25 years of technology advances, the industry underwent a robust era of technology development in its rush to crack the shale development riddle. Since 1999, the industry also delivered a 36% increase in global supplies, as noted in this JPT story celebrating this industry’s biggest innovations. 1999 represents an interesting turning point in the industry’s technological journey. Also, it is the last time JPT editors took the opportunity to celebrate the publication as it turned 50 years old that year. What follows are a few highlights from JPT’s coverage of advances and changes made in artificial lift applications and practices over the past quarter century.

Optimization of Exergy Efficiency in a Walking Beam Reheating Furnace Based on Numerical Simulation and Entropy Generation Analysis

An analysis of entropy generation and exergy efficiency can effectively explore the energy-saving potential of reheating furnaces. This paper simulated the combustion, flow, and heat transfer in a walking beam reheating furnace by establishing a half-furnace model. The entropy generation rate distribution of different thermal processes was numerically calculated. The effect of slab residence time and fuel distribution in the furnace was studied to optimize exergy efficiency. The results indicated that combustion and radiative heat transfer are the primary sources of entropy generation. Irreversible losses accounted for 26.39% of the total input exergy, in which the combustion process accounted for 16.43%, and radiative heat transfer accounted for 8.47%. Reducing the residence time by 60 min decreased irreversible exergy loss by about 2.5% but increased heat dissipation and exhaust exergy loss by 5.8%. Energy saving can only be achieved when the heat exchanger’s exergy recovery efficiency exceeds 36% under different fuel supplies. Keeping the total fuel supply unchanged, increasing the fuel mass flow rate in heating-I zone while decreasing it in heating-II zone resulted in a 1.5% decrease in exergy efficiency. This study provides new insights into the energy-saving potential of reheating furnaces.

Chronic Ankle Joint Instability Induces Ankle Sensorimotor Dysfunction: A Controlled Laboratory Study.

Chronic ankle instability (CAI) is a clinical sequela that causes the recurrence of ankle sprain by inducing ankle sensorimotor dysfunction. Animal models of CAI have recently shown that ankle ligament injuries mimicking an ankle sprain result in chronic loss of ankle sensorimotor function. However, the underlying mechanisms determining the pathogenesis of CAI remain unclear. Ankle instability after an ankle sprain leads to the degeneration of the mechanoreceptors, resulting in ankle sensorimotor dysfunction and the development of CAI. Controlled laboratory study. Four-week-old male Wistar rats (N = 30) were divided into 2 groups: (1) the ankle joint instability (AJI) group with ankle instability induced by transecting the calcaneofibular ligament (n = 15) and (2) the sham group (n = 15). Ankle instability was assessed using the anterior drawer test and the talar tilt test at 4, 6, and 8 weeks after the operation (n = 5, for each group at each time point), and ankle sensorimotor function was assessed using behavioral tests, including ladder walking and balance beam tests, every 2 weeks during the postoperative period. Morphology and number of mechanoreceptors in the intact anterior talofibular ligament (ATFL) were histologically analyzed by immunofluorescence staining targeting the neurofilament medium chain and S100 proteins at 4, 6, and 8 weeks postoperatively (n = 5 per group). Sensory neurons that form mechanoreceptors were histologically analyzed using immunofluorescence staining targeting the mechanosensitive ion channel PIEZO2 at 8 weeks postoperatively (n = 5). Ankle sensorimotor function decreased over time in the AJI group, exhibiting decreased ankle instability compared with the sham group (P = .045). The number of mechanoreceptors in the ATFL was reduced (P < .001) and PIEZO2 expression in the sensory neurons decreased (P = .008) at 8 weeks postoperatively. The number of mechanoreceptors was negatively correlated with ankle sensorimotor dysfunction (P < .001). The AJI model demonstrated degeneration of the mechanoreceptors in the ATFL and decreased mechanosensitivity of the sensory neurons, which may contribute to CAI. Ankle instability causes degeneration of mechanoreceptors and decreases the mechanosensitivity of sensory neurons involved in the development of CAI. This finding emphasizes the importance of controlling ankle instability after ankle sprains to prevent recurrence and the onset of CAI.

Effects of Furnace Length on the Thermal Performance of a Walking Beam Reheating Furnace

The influence of furnace length on several key performance indicators of a reheating furnace such as the fuel consumption, thermal efficiency and through-thickness temperature uniformity of a discharged slab was investigated. Energy balance equations of radiation set up by the zone method were solved by coupling them with the heat conduction equations of the slab. The zone model was validated by actual data collected during an instrumented slab trial. The simulation results showed that the model predictions were in good agreement with actual measurements. Under the premise that the throughput rate and the total fuel consumption were fixed, every additional meter of the preheating zone length increased the slab discharge temperature by about 10.75 °C and decreased the exhaust temperature by about 13.29 °C, but made no change in the section temperature difference in the slab at discharge; every additional meter of the soaking zone length decreased the section temperature difference in the slab at discharge by about 2.88 °C, but made a somewhat gentle change in the slab discharge temperature and exhaust temperature. For the existing furnace, the actual length was not suitable to be changed, so the relative length was defined as representing the actual length, which could be indirectly changed by adjusting the current fuel consumption. After optimization, the relative lengths of the preheating zone and soaking zone increased by five meters and one meter, respectively, while the relative lengths of the first and second heating zones decreased by five meters and one meter, respectively, and the section temperature difference in the slab at discharge, exhaust temperature and fuel consumption simultaneously decreased.

Computational Modeling of Walking Beam Type Reheat Furnace for the Prediction of Slab Heating and Scale Formation

Abstract Computational modeling using the high-viscosity laminar flow approach was applied to study the effect of slab crossing time on slab heating and scale growth. Simulation of an existing industrial walking beam reheating furnace with four zones, outer refractory body, skid, slab, and fluid zone is considered. The fuel used was a mixture of coke oven and blast furnace gas. Preheated air is supplied co-axially with the fuel mixture. The combustion simulation is performed using the constrained equilibrium mixture fraction model. From the results, it has been observed that with an increase in slab residence time, the slab temperature and scale growth increase across the slab. For the system considered, with a fuel mass flowrate of 70,000 kg/h, 150–180 min of slab crossing time is appropriate to obtain desired slab temperature at the discharge end. The overall equivalence ratio is taken as Φ = 1 (fuel/air ratio is the same as stoichiometric ratio). The maximum slab scale thickness is evaluated as 2.4 mm at the discharged end for 180 min of slab crossing time.

Reducing skid marks on steel slabs by developing an improved design scheme of water beam

Due to the existence of cooling water pipes and thermoduric skids in the walking beam type reheating furnace, skid marks always occur on the bottom of the steel slab and the quality of the steel slab is seriously affected. In this paper, the coupled heat transfer model among steel slab, water beam, furnace gas and furnace walls is established to accurately simulate the reheating process of the steel slab. The discrete ordinates method (DOM) is adopted to solve radiative heat transfer problem in reheating furnace. To get closer to the real situation, the relative movement between steel slab and thermoduric skid is taken into account strictly. The formation process of skid mark is clarified based on the calculated results of coupled heat transfer, and an improved design scheme for water beam is proposed to make the new skid marks produced after water beam dislocation not overlap each other, which effectively reduces the skid marks. Our study can provide helpful advising for the improvement of steel slab quality and the design of water beam structure in reheating furnace.

The modeling and identification of walking beam type slab reheating furnace based on immersion and invariance disturbance estimation

This paper presents the modeling and identification of a walking-beam-type slab reheating furnace in one of the biggest Iron and Steel Industry in Turkey. Firstly, the dynamical model of the furnace is established as it is running with 12 control zones based on energy balance equations in the zones. Secondly, a disturbance observer is designed to estimate the disturbances that represents unmeasurable energy losses and the effects of unknown dynamics of the system based on Immersion and Invariance (I&I) approach. Then, model is identified with real data collected from the running furnace. The model and real furnace outputs are compared zone by zone. The results demonstrate the validity of the model.

Analyzing the effect of vehicle speed and class of random road profile on a 4-axle truck vehicle vibration

The vehicle will generate vibration due to the impact of road surface, wind, steering, accelerating, braking...as it moves on road surfaces. These vibrations directly affect people and goods. A 14 DOF full vehicle dynamic model of the 4-axle truck vehicle with the torsion of the chassis and the “Walking Beam” tandem suspension is developed to analyze the effect of vehicle speed and a class of random road profile conditions on the vibration of the 4-axle truck vehicle which is developed based on Newton Euler equations and solved via Matlab/Simulink software. The study results have shown that the road surface and vehicle speed conditions have a great effect on vehicle vibrations. In addition, the results of this study could provide useful analysis results for proposing solutions to optimize the structure of the suspension system to improve the ride comfort of the vehicle and reduce the dynamic load of multi-axle truck vehicles.

A combined adaptive entropy‐TOPSIS and model predictive control strategy for mixed loading and delay operations in the reheating furnace

SummaryIn this paper, a combined adaptive entropy‐TOPSIS and model predictive control strategy is proposed to deal with the mixed loading and delay operations in the reheating furnace. Firstly, the mathematical models consistent with the behaviour of the real reheating furnace are built to describe the complicated heat exchange process. Secondly, a dynamical optimization problem for the mixed loading operation and delay operation in the walking beam reheating furnace is obtained. To adjust the weighting factors of the optimization problem in real time, the adaptive entropy‐TOPSIS method is proposed. Then, the rolling horizon approach is applied to solve the proposed optimization problem. Finally, numerical experiments and simulation analysis are undertaken to verify the reliability and accuracy of the proposed strategy. The simulation results demonstrate that the proposed strategy can deal with three typical cases of delays effectively and the control accuracy is successfully improved from 74.79% to 99.17%.

Multi-Mode Model Predictive Control Approach for Steel Billets Reheating Furnaces.

In this paper, a unified level 2 Advanced Process Control system for steel billets reheating furnaces is proposed. The system is capable of managing all process conditions that can occur in different types of furnaces, e.g., walking beam and pusher type. A multi-mode Model Predictive Control approach is proposed together with a virtual sensor and a control mode selector. The virtual sensor provides billet tracking, together with updated process and billet information; the control mode selector module defines online the best control mode to be applied. The control mode selector uses a tailored activation matrix and, in each control mode, a different subset of controlled variables and specifications are considered. All furnace conditions (production, planned/unplanned shutdowns/downtimes, and restarts) are managed and optimized. The reliability of the proposed approach is proven by the different installations in various European steel industries. Significant energy efficiency and process control results were obtained after the commissioning of the designed system on the real plants, replacing operators' manual conduction and/or previous level 2 systems control.

Mathematical model of slab heating in a furnace with walking beams

Slab heating before hot rolling is necessary for obtaining required metal ductility. The most effective for this purpose are furnaces with walking beams that provide heat supply to all sides of the slab. However, the areas of slabs lower surfaces, contacting with water-cooled beams, are shielded from the radiation of the furnace lower heating zones and take the heat from the beams.To study the inhomogeneity of the slab temperature field and its dependence on the peculiarities of their transport system design, a mathematical model of slab heating in a furnace with walking beams was developed and programmatically implemented, based on numerical solution of a three-dimensional heat conduction problem with piecewise defined boundary conditions on the lower surface. For the open areas of the slab bottom surface, the same boundary conditions were set as on the top surface; and for the areas of contact with the beams, modified boundary conditions were set, taking into account the duration of this contact. For the numerical solution of the system of difference equations, the line-by-line method was applied, which allows us to obtain a system with a three-diagonal matrix of coefficients. The calculations carried out in the approximation of adiabaticity of the contact areas of the slab with the beams during the contact period allowed us to obtain temperature fields for different slab sections. As a result, a significant irregularity of temperature field of the slab lower surface was revealed, affecting the irregularity of temperature field of the entire slab. The developed program for calculating and visualizing the results can be used to study the temperature field of the slab under various heating modes if there is experimental information that allows one to clarify the tuning parameters of the model.

Сontinuous walking beam furnace without water cooling for reheating copper alloy blanks

It takes a special technique to heat up round blanks cast of copper alloys in conformance with applicable process specification, which implies maintaining a low oxidizing atmosphere in a gas furnace. This paper describes a continuous furnace with walking beams that are not watercooled designed to heat up round blanks to the maximum temperature of 1,000 &ordm;C. The furnace, which stands before the pipe press for making pipes of different sizes, is fueled by natural gas burned in high-speed burners with the air flow rate of &alpha; = 0.98 in hot zones and that of &alpha; = 1.05&ndash;1.1 in preheating zones. The side walls of the furnace are equipped with high-speed burners which serve to intensify the convective heat transfer inside the furnace. The burners ensure a transverse/countercurrent flow of gases with an intense transverse jet circulation. The furnace is equipped with a panel roof lined with ribbed ceramic fiber blocks (original design by UralTermoKompleks) which serves to intensify the radiation heat transfer without raising the temperature. A larger interior surface of the furnace roof leads to an increased radiation heat flow density and hence higher heating rates. It means that the furnace has better performance at the same temperature. The furnace is equipped with charging and discharging systems. An eccentric is responsible for moving the walking beams. An integrated control system controls heat in each of the five zones of the furnace guided by thermocouples and charging and discharging modes. The furnace has been fully commissioned.