Numerical Simulation of the Effect of Air Distribution on Turbulent Flow and Combustion in a Tubular Heating Furnace

A three-dimension full-size numerical simulation of the effect of air distribution on turbulent flow and combustion in a tubular heating furnace was carried out. A standard k –ε turbulent model, a simplified PDF combustion model and a discrete ordinate transfer radiation model were used. The hybrid grid combining a structured and a non-structured grid was generated without any simplification of the complicated geometric configuration around the burner. It was found that the multistage combustion could reduce and control the peak value of temperature. At the same time, it was concluded that the amount of primary air had little effect on the global distribution of velocity and temperature in the furnace, but a great effect on that around the burner. It is recommended that 45% - 65% of the total amount of air be taken in in primary air inlets in the furnace. All the results are important to optimize the combustion progress.

Improvement of fuel consumption and maintenance of heating furnaces using a modified heating pattern

This article studies the transient heat conduction in a slab when passing through various sections of the furnace, and focuses on the thickness of the scale layer formed on the slab. The transient heat conduction behavior of a slab in various sections of the heating furnace is analyzed using the Laplace transformation method, including the pre-heating zone, the first heating zone, the second heating zone, and the soaking zone. The heating pattern of the furnace is then modified to reduce fuel consumption. The simulation results show that the scale layer formed on the slab significantly influences the quality of the hot rolled coil formed, and how the furnace parameters affect the efficiency of the furnace and the quality of the coil.

Parameters Optimization of the Heating Furnace Control Systems Based on BP Neural Network Improved by Genetic Algorithm

The heating technological requirement of the conventional PID control is difficult to guarantee which based on the precise mathematical model,because the heating furnace for heating treatment with the big inertia,the pure time delay and nonlinear time-varying.Proposed one kind optimized variable method of PID controller based on the genetic algorithm with improved BP network that better realized the completely automatic intelligent control of the entire thermal process than the classics critical purporting(Z-N)method.A heating furnace for the object was simulated with MATLAB,simulation results show that the control system has the quicker response characteristic,the better dynamic characteristic and the quite stronger robustness,which has some promotional value for the control of industrial furnace.

Finite-time Stability of Heating Furnace Temperature Control System

A finite-time stabilization controller for the heating furnace temperature control system is proposed.Based on the extended Lyapunov finite-time stability theory and power integral method,a finite-time stable condition of the heating furnace temperature control system is given.The temperature of the heating furnace is directed by the finite-time stabilization controller to make it stable in finite time.And the quality and quantity of slabs is improved.The simulation example is presented to illustrate the applicability of the developed results.

Process metallurgy and data-driven prediction and feedback of blast furnace heat indicators

The prediction and control of furnace heat indicators are of great importance for improving the heat levels and conditions of the complex and difficult-to-operate hour-class delay blast furnace(BF)system.In this work,a prediction and feedback model of furnace heat indicators based on the fusion of data-driven and BF ironmaking processes was proposed.The data on raw and fuel materials,process op-eration,smelting state,and slag and iron discharge during the whole BF process comprised 171 variables with 9223 groups of data and were comprehensively analyzed.A novel method for the delay analysis of furnace heat indicators was established.The extracted delay variables were found to play an important role in modeling.The method that combined the genetic algorithm and stacking efficiently im-proved performance compared with the traditional machine learning algorithm in improving the hit ratio of the furnace heat prediction model.The hit ratio for predicting the temperature of hot metal in the error range of±10℃ was 92.4%,and that for the chemical heat of hot metal in the error range of±0.1wt%was 93.3%.On the basis of the furnace heat prediction model and expert experience,a feedback model of furnace heat operation was established to obtain quantitative operation suggestions for stabilizing BF heat levels.These sugges-tions were highly accepted by BF operators.Finally,the comprehensive and dynamic model proposed in this work was successfully ap-plied in a practical BF system.It improved the BF temperature level remarkably,increasing the furnace temperature stability rate from 54.9%to 84.9%.This improvement achieved considerable economic benefits.

Three-Dimensional Concurrent Design System for Walking-Beam Furnace

This paper focuses on the problem of low efficiency and limited non-geometric information handling ability in the process of 2D heating furnace design, proposes a 3D concurrent parametric design system, this method is realized by parametric design technology, which is supported by ActiveX-Automation technology and VBA technology, mutual visit between application programs makes batched modeling become possible, key dimensions are linked with each other by restrictions, so parts can be built concurrently by sharing few parameters between common borders, designer can be free from repeated drawing work during modification, Solid Edge is chosen as the modeling server, a secondary development software is programmed by Visual Basic, this system provides a feasible way to overlap time between different sections, the design efficiency and quality is improved significantly.

Effect of roller shapes on strip buckling in a continuous annealing furnace

The effect of roller shapes on strip buckling in a continuous annealing furnace was focused on. The tensile stress distribution, the transverse compressive stress, and the critical buckling stress of the strip were studied by the finite element method （FEM） when the flat roller, crown roller, single taper roller, and double taper roller were used, respectively. Simulation results show that strip buckling is most likely to occur with the crown roller, then the double taper roller, and finally the single taper roller. Also, strip buckling can not occur when the flat roller is used. Considering strip snaking, the single taper roller and double taper roller are suggested in the continuous annealing fur-nace. The double taper roller with a better strip snaking-prevention ability should be applied in the sections with high strip temperature, and the single taper roller with a better buckling-prevention ability should be used in the sections with low strip temperature.

Theory,Method and Application of a State Recognition Based on Theory of Evidence

A new method of state recognition based on the theory of evidence was proposed. By this method, the plausible function which the sample awaiting recognition belongs to each category can be obtained through distance function. For the marginal samples,two or a batch of evidences can be combined and a new plausible function can be obtained by new evidence. Then the categories of samples can be determined according to plausibility function. This method provides a beder reasoning framework. The result proves the rate of recoghition correctness.

NOx Emission Characteristics in Radiant Tube Burner with Oscillating Combustion Technology

An experimental study was carried out in a small-scale furnace to investigate the performance, such as NOx emission, enhancement of heat transfer, uniformity of temperature, and etc., of oscillating combustion applied in radiant tube burner sy stem for heat treatment furnace. A premixed type burner and a solenoid type oscillating control valve were designed and used. The fuel was used commercial LPG in this study and the fuel flow was oscillated by periodically opening and shutoff of the solenoid valve. From the tests, it was found that NOx emission, compared to no oscillation, could be reduced by 32% at 2.0 Hz. However, as oscillating frequency was increased, abatement of NOx emission was gradually reduced. At the high NOx abatement of 1.0 Hz, carbon monoxide was emitted above 10,000 ppm. Although rate of NOx abatement was low, oscillation condition of 2.5 Hz and duty ratio of 10-30% was recommended for low carbon monoxide emission. From the measurement of furnace heating time from 100 ℃ to 720 ℃, it was shown that heat transfer was increased by 11.5% at 2 Hz oscillating frequency. Temperature distribution of radiant tube surface was more uniform at 2 Hz oscillating frequency with drop of the peak temperature and rise of low temperature. From these results, it was confirmed that oscillating combustion was useful in radiant tube burner system.

Numerical Analysis of Flow Instability in the Water Wall of a Supercritical CFB Boiler with Annular Furnace

In order to expand the study on flow instability of supercritical circulating fluidized bed(CFB) boiler,a new numerical computational model considering the heat storage of the tube wall metal was presented in this paper.The lumped parameter method was proposed for wall temperature calculation and the single channel model was adopted for the analysis of flow instability.Based on the time-domain method,a new numerical computational program suitable for the analysis of flow instability in the water wall of supercritical CFB boiler with annular furnace was established.To verify the code,calculation results were respectively compared with data of commercial software.According to the comparisons,the new code was proved to be reasonable and accurate for practical engineering application in analysis of flow instability.Based on the new program,the flow instability of supercritical CFB boiler with annular furnace was simulated by time-domain method.When 1.2 times heat load disturbance was applied on the loop,results showed that the inlet flow rate,outlet flow rate and wall temperature fluctuated with time eventually remained at constant values,suggesting that the hydrodynamic flow was stable.The results also showed that in the case of considering the heat storage,the flow in the water wall is easier to return to stable state than without considering heat storage.