Software sensor for slab reheating furnace

It has long been thought that a reheating furnace, with its inherent measurement difficulties and complex dynamics, posed almost insurmountable problems to engineers in steel plants. A novel software sensor is proposed to make more effective use of those measurements that are already available, which has great importance both to slab quality and energy saving. The proposed method is based on the mixtures of Gaussian processes (GP) with the expectation maximization (EM) algorithm employed for parameter estimation of the mixture of models. The mixture model can alleviate the computational complexity of GP and also accords with the changes of operating condition in practical processes. It is demonstrated by on-line estimation of the furnace gas temperature in 1580 reheating furnace in Baosteel Corporation (Group).     

Dynamic simulation on effect of flame arrangement on thermal process of regenerative reheating furnace

By analyzing the characteristics of combustion and billet heating process, a 3-D transient computer fluid dynamic simulation system based on commercial software CFX4.3 and some self-programmed codes were developed to simulate the thermal process in a continuous heating furnace using high temperature air combustion technology. The effects of different switching modes on injection entrancement of multi burners, combustion and billet heating process in furnace were analyzed numerically, and the computational results were compared with on-site measurement, which verified the practicability of this numerical simulation system. The results indicate that the flow pattern and distribution of temperature in regenerative reheating furnace with partial same-side-switching combustion mode are favorable to satisfy the high quality requirements of reheating, in which the terminal heating temperature of billets is more than 1 460 K and the temperature difference between two nodes is not more than 10 K. But since the surface average temperature of billets apart fi＇om heating zone is only about 1 350 K and continued heating is needed in soaking zone, the design and operation of current state are still needed to be optimized to improve the temperature schedule of billet heating. The distribution of velocity and temperature in regenerative reheating furnace with same-side-switching combustion mode cannot satisfy the even and fast heating process. The terminal heating temperature of billets is lower than that of the former case by 30 K. The distribution of flow and temperature can be improved by using cross-switching combustion mode, whose terminal temperature of billets is about 1 470 K with small temperature difference within 10 K.     

Numerical simulation of fluid flow in a reheating furnace with multi-swirling-burners

A general numerical simulating program for three-dimensional (3-D) and time-dependent fluid flow for a reheating furnace with multi-swirling-burners has been developed based upon an arbitrary Lagrangian-Eulerian scheme (ALE) with the finite volume method. The parameters of fluid flow in a reheating furnace with multi-swirling-burners was calculated and the 3-D velocity distributions were obtained. The design of the burners was optimized for forming better swirling flow. The simulation shows that the fluid flow in the reheating furnace with the optimized burners is reasonable.     

Microstructure and properties of high emissivity coatings

A new coating on lining in industrial furnace for energy saving has been developed. Properties and microstructure of the coatings were revealed by emissivity instrument,X-ray diffraction (XRD),transmission electron microscope (TEM) and scanning electron microscope (SEM),respectively. The result indicates that the emissivity of coatings is higher than 0.90 and the thickness of coatings is about 200 μm. ZrO2,Cr2O3 and SiC in the coating benefit practical applications of coatings at high temperature with du-ra...     

Design of Fuzzy Controller for Central Air Conditioner

A structure of central air conditioning system in building and its running pattern are proposed in orderto perform optimum energy saving strategy. The design of room temperature controller is taken as an example todiscuss the design of fuzzy controller using common microprogrammed control unit(MCU)in detail. Based onfuzzy theory the query control tables fixed in read only memory(ROM) of MCU are established to realize the     

Neural adaptive PSD decoupling controller and its application in three-phase electrode adjusting system of submerged arc furnace

Taking three-phase electrode adjusting system of submerged arc furnace as study object which has nonlinear, time-variant, multivariable and strong coupling features, a neural adaptive PSD(proportion, sum and differential) dispersive decoupling controller was developed by combining neural adaptive PSD algorithm with dispersive decoupling network. In this work, the production technology process and control difficulties of submerged arc furnace were simply introduced, the necessity of establishing a neural adaptive PSD dispersive decoupling controller was discussed, the design method and the implementation steps of the controller are expounded in detail, and the block diagram of the controlled system is presented. By comparison with experimental results of the conventional PID controller and the adaptive PSD controller, the decoupling ability, adaptive ability, self-learning ability and robustness of the neural adaptive PSD dispersive decoupling controller have been testified effectively. The controller is applicable to the three-phase electrode adjusting system of submerged arc furnace, and it will play an important role for achieving the power balance of three-phrase electrodes, saving energy and reducing consumption in the process of smelting.     

The performance analysis and calculation for variable frequency speed control motors with the rotor structure optimized

With the popularization of energy saving technolo-gy,variable frequency speed control motors,with parti-cular operation characteristics and energy savingeffects,are in greater and greater demand at home andabroad.It is no doubt a chance to challenge our coun-try in the variable frequency speed control motor busi-ness.So it is important to develop highly efficient andenergy saving variable frequency speed control motors.In a traditional motor design and analysis method,the parameters in equival…     

Effect of quenching and partitioning process on MA constituent in Nb-bearing HSLA steel

The effect of quenching-partitioning (Q-P) process on martensite-austenite (MA) constituent is investigated by the thermo-analysis simulator for a niobium-bearing HSLA steel. The process includes quenching from 950 ℃ to the intermediate temperature of 350-550 ℃ at the rate of 30 ℃/s and subsequent reheating at the rate of 20-50 ℃/s and partitioning at 660-800 ℃. The microstructure is characterized by nano probe, EBSD, colored metallograph, optical microscope and graphic analytic method. The results show that the improvement of distribution homogeneity of MA in microstructure, the diminishment of the MA average grain size and increment of the MA volume fraction is caused by the intermediate temperature decrease, the reheating rate increase and a proper partitioning temperature. The volume fraction of MA is up to 7.9% while the sample is quenched to 450 ℃, reheated at 50 ℃/s and partitioned at 750 ℃. The grain is granular or equiaxed in shape and the average grain size of MA is about 0.77-1.48 μm after treated by Q&P process. The grains tend to be coarse and with sharpy-angle as the intermediate temperature is up and the reheating rate and the partitioning temperature rises. The MA volume fraction depends on the untransformed austenite volume fraction after quenching and carbon diffusion time and temperature during partitioning process.     

Isothermal reduction of titanomagnetite concentrates containing coal

The isothermal reduction of the Panzhihua titanomagnetite concentrates （PTC） briquette containing coal under argon atmosphere was investigated by thermogravimetry in an electric resistance furnace within the temperature range of 1250-1350°C. The samples reduced in argon at 1350°C for different time were examined by X-ray diffraction （XRD） analysis. Model-fitting and model-free methods were used to evaluate the apparent activation energy of the reduction reaction. It is found that the reduction rate is very fast at the early stage, and then, at a later stage, the reduction rate becomes slow and decreases gradually to the end of the reduction. It is also observed that the reduction of PTC by coal depends greatly on the temperature. At high temperatures, the reduction degree reaches high values faster and the final value achieved is higher than at low temperatures. The final phase composition of the reduced PTC-coal briquette consists in iron and fer-rous-pseudobrookite （FeTi2O5）, while Fe2.75Ti0.25O4, Fe2.5Ti0.5O4, Fe2.25Ti0.75O4, ilmenite （FeTiO3） and wustite （FeO） are intermediate products. The reaction rate is controlled by the phase boundary reaction for reduction degree less than 0.2 with an apparent activation energy of about 68 kJ·mol-1 and by three-dimensional diffusion for reduction degree greater than 0.75 with an apparent activation energy of about 134 kJ·mol-1. For the reduction degree in the range of 0.2-0.75, the reaction rate is under mixed control, and the activation energy increases with the increase of the reduction degree.     

Forming condition and control strategy of ferrite decarburization in 60Si2MnA spring steel wires for automotive suspensions

The ferrite decarburization behavior of 60Si2MnA spring steel wires for automotive suspensions, including the forming condition and the influence of heating time and cooling rate after hot rolling, was investigated comprehensively. Also, a control strategy during the reheating process and cooling process after rolling was put forward to protect against ferrite decarburization. The results show that ferrite decarburization, which has the strong temperature dependence due to phase transformation, is produced between 675 and 875°C. The maximum depth is found at 750°C. Heating time and cooling rate after rolling have an important influence on decarburization. Reasonable preheating temperature in the billet reheating process and austenitizing temperature in the heat-treatment process are suggested to protect against ferrite decarburization.     

热轧轧钢加热炉热装制度的优化研究

基于钢坯跟踪测试和热平衡测试,联立加热炉温度分布模型、钢温模型和热平衡模型,对不同炉型、不同钢种和不同热装温度条件下,加热炉钢坯加热过程进行数值模拟和温度制度优化。获得不同钢种在不同热装温度条件下的优化加热制度,为加热炉的节能降耗和科学操作提供了理论依据。     

蓄热燃烧技术在超大炉宽加热炉上的应用

着重叙述了双蓄热燃烧技术在超大炉宽板坯加热炉上的开发应用,以及取得的节能效果。     

钢坯加热炉炉温仿人智能控制策略的研究

针对钢坯加热炉炉温控制现状及存在的问题,依据仿人智能控制原理,建立炉温的仿人智能控制策略.并利用MATLAB仿真软件对仿人智能控制算法与常规PID控制算法进行对比仿真实验,结果表明仿人智能控制策略在炉温控制方面有较好的控制效果和更强的适应性.     

加热炉热过程数学模型与燃烧过程计算机控制的研究

结合包钢带钢厂加热炉具体情况，对加热炉热过程数学模型的建立与数值求解方法进行了全面的阐述和分析，以加热炉数学模型数据库为基础，开发与研制出了包钢带钢厂加热炉燃烧过程计算机控制系统，构造炉温控制模块与空燃比优化控制模块，实现加热炉的优化燃烧，达到节能降耗的目的。     

热轧加热炉最优加热制度的研究

依据热平衡实验和“黑匣子”钢温测试实验,建立大型板坯加热炉离线仿真计算模型。经实验验证,模型计算准确,计算误差小于4％,满足工业计算要求。通过该离线模型的仿真计算,实现大型加热炉多段加热温度的优化,获得最佳供热制度,为加热炉的优化控制和操作、降低能耗、提高节能率提供指导。     

加热炉钢坯温度场的预报模型

利用神经网络建模方法建立钢坯表面温度场的预报模型,设计了网络结构,进行了仿真研究和分析,该模型可以较好地满足工程需要,有利于提高加热炉的控制水平及节约能源。并通过有限差分法建立钢坯内部温度场模型,该模型可以计算出任意时刻钢坯的温度场。     

攀钢热轧加热炉自动燃烧控制系统的周期计算

介绍了在攀钢1450热轧板厂两座265 t/h的步进梁式加热炉上开发应用的L1,L2两级燃烧控制系统,其中,L1级燃烧自动控制系统主要实现如何以最快的响应速度完成以温度为目标的燃烧控制;L2级燃烧自动控制技术,主要实现在线情况下,考虑不同钢坯材质、规格、不同轧制规格、不同的组织计划、不同的钢坯装入温度、不同的生产节奏下(与轧线一体控制的)的燃烧温度的设定模型技术,以数学手段计算出在各种因素影响下,加热炉各个控制段的最佳加热温度。重点阐述了加热炉自动燃烧控制模型的核心———ACC模型周期计算处理的方法。     

两种非灰气体辐射特性模型的研究

加热炉内的传热以非灰气体参与的辐射换热为主,准确求解炉气的辐射特性对于炉子热过程数学模型至关重要．本文考察了两种非灰气体辐射特性模型,即Edwards指数宽带模型和Leckner级数式,并应用这两种模型计算了二氧化碳和水蒸气的辐射特性．结果表明,在加热炉的工作温度和压力行程范围内,两种模型在总体上具有相当的精度,但是在实际生产过程中,却有必要根据模型的计算精度、采用的燃料不同和现场的硬件设备及其存储和耗时的要求,对二者的最优适用范围予以区分．     

基于阀门开度的加热炉模糊专家控制

针对具有多变量、时变、非线性、强耦合等特点的加热炉燃烧控制过程,采用模糊控制、专家系统等技术建立了加热炉燃烧过程智能控制系统,提出了直接针对空气阀门开度和煤气阀门开度的模糊专家控制技术。该模糊专家控制系统能根据炉温偏差和炉温偏差变化率直接获得阀门开度的设定值,从而对加热炉燃烧过程进行自动控制,大大提高了炉温控制精度和升降温速度,实现了炉温的实时、准确控制,稳态控制精度为5%。解决了常规控制中存在超调量大、升降温速度慢和实时性差等问题。系统已投入运行,产生了显著的经济效益和社会效益。