Data Driven Prediction of Sintering Burn-Through Point Based on Novel Genetic Programming

 The paper presents an empirical dynamic model of burn-through point (BTP) in sintering process. The model combines two stages of sintering process, cold processing stage and sintering stage. Fist, cold bed permeability measured by Gas velocity is introduced in the cold stage. Then, K-Means clustering is applied to partition the feed according to the permeability. Besides, for each clustering, a novel genetic programming (NGP) is proposed to construct the empirical model of the waste gas temperature and pressure drop through the bed in sintering stage. NGP adopts least square method (LSM) and M-estimator to improve the ability to compute and resist disturbance. Therefore, the paper constructs a model base of burn-through point and the simulation proves that the model base has a good performance.     

Study of moisture transfer during the strand sintering process

Moisture transfer during the strand sintering operation was studied both experimentally and using a mathematical model. The drying of iron ore pellets was found to occur in two distinct periods: one at a constant drying rate and the other at a decreasing drying rate, whereas the drying of zinc ore pellets always occurs at a decreasing drying rate. Characteristic drying curves were determined for both materials. The moisture transfer mechanisms during the sintering process were demonstrated in detail, including the recondensation of water in the cold layers of the bed and the formation of an inert, overmoistened zone. The mathematical model presented simulates all of these phenomena and is used to calculate the variables related to moisture transfer. The model is adaptable to other processes where a hot gas passes through a moist packed bed.     

Process simulation of iron ore sintering bed with flue gas recirculation

Abstract

As issues of productivity, quality control, energy efficiency and environmental regulation become ever more important in the iron ore sintering process, controlling combustion inside the sinter bed is attracting renewed interest in terms of flue gas recirculation (FGR) and oxygen or gaseous fuel enriched combustion. The application of combustion control schemes inevitably brings changes to incoming and outgoing gas conditions as well as to plant configuration. The objective of this study is to build a process model of a sintering bed using a flowsheet process simulator and to obtain information on material flows for various process configurations and operating conditions. The process modelling was designed to quantify the heat and mass flow in each of the bed segments, which could then be integrated to represent the overall material and energy flow of the entire bed. Variations in incoming and outgoing gas conditions were compared among different configurations of recirculation using the model.     

莱钢烧结机废气余热回收利用实践

莱钢3×265m^2烧结机成功设计安装以热管为主要传热元件的余热回收装置,将环冷高温段废气转化为热蒸汽并应用于生产和生活;中温段热废气通过热风罩引入烧结料面,采用环冷机安装平料器、改进密封方式、改造烧结机布料系统、优化工艺操作参数以改善料层透气性等一系列措施,充分利用烧结矿显热资源实现了热风烧结。废气余热的回收利用,大大降低了烧结工序能耗,减少了热源排放,经济效益和环保效益显著。     

Analysis of flue gas emission law in sintering process of iron mine

In order to study the emission law of COx in the sintering flue gas, firstly, the fuel combustion behavior in the sintering process was studied and the generation mechanism of COx was analyzed. Then, the sintering process in the production site was simulated. Sintering flue gas was detected by the flue gas analyzer. Flue gas temperature, negative pressure, and flue gas composition were analyzed. The correlation between the change of flue gas parameters and the state of sinter bed was analyzed. The experimental results can be concluded that the main factor affecting the mass concentration of CO in the sintered flue gas is temperature. The changes of CO, CO2 and NOx mass concentrations are consistent and negatively correlated with the changes of O2 gas volume fraction.CO, SO2 and NOx concentrations have the same extreme time, and the flue gas temperature reaches the fastest rising period. The golden stage of staged treatment of CO in flue gas is from the end of sintering ignition to the rise of flue gas temperature.     

铁矿烧结过程烟气排放规律分析

摘要：为了研究烧结烟气中COx的排放规律,首先对烧结工序中燃料燃烧行为进行研究,分析COx的生成机制。然后模拟生产现场烧结过程,使用烟气分析仪对烧结烟气进行检测,分析烟气温度、负压、烟气成分等数据,并结合烧结料层状态解析了烟气参数变化与料层状态之间的相关联性。实验结果得出,影响烧结烟气中CO质量浓度的主要因素是温度;CO、CO2和氮氧化物质量浓度变化一致,与O2气体积分数变化负相关;CO、SO2和氮氧化物浓度有相同的极值时间,此时烟气温度达到最快上升期;烧结点火结束之后至烟气温度上升之前是分段处理烟气中CO的黄金阶段。     

Factors influencing the production rate and quality of lead sinter

The sintering characteristics of a typical Missouri lead concentrate were determined for two types of raw sinter mix: conventionally prepared and pelletized. The important sintering characteristics are sulfur elimination, sinter strength, production rate of sinter, permeability of the sinter bed, and bed temperature. These characteristics were analyzed statistically, and are described by an empirical model, in which proportion of returns, moisture content, air flow, bed height, size distribution of returns, and ignition time are the independent variables. The characteristics of a conventionally prepared sinter mix are most strongly affected by the moisture content of the raw mix. The characteristics of a pelletized sinter mix are not strongly affected by any of the independent variables. However, a pelletized charge gave a much higher production rate and a higher sinter quality as compared to a conventionally prepared charge. Recycle of off gas has a large deleterious effect on sinter production rate and quality. The results provide suggestions for improved operation of sinter plants.     

COREX冷煤气成分预测的二步建模方法

针对熔融气化炉冷煤气成分含量,提出了基于熵权模糊C均值聚类和偏最小二乘的COREX冷煤气成分预测方法.建模过程中首先根据料单中各种原料的单耗量,利用熵权模糊C均值聚类的方法将料单聚类成若干种料单类别,然后针对不同的料单类别,利用偏最小二乘法分别建立冷煤气成分预测模型.对宝钢COREX-1#炉实际生产数据验证结果表明:该方法可以有效地建立COREX冷煤气成分预测模型,具有较好的预测精度.      

Effect of H2 O(g)Content in Circulating Flue Gas on Iron Ore Sintering with Flue Gas Recirculation

The influence of H_2O(g) content in circulating flue gas on sintering was studied by simulating the flue gas circulating sintering.The results show that the burning speed of solid fuel and the heat transfer rate during sintering process are improved when the H_2O(g) content increases from 0 to 6%,which accelerates the sintering speed.However,when the H_2O(g) content exceeds 6%,the over-wet zone in sinter bed is thickened,which deteriorates the permeability of sintering bed.In addition,the magnetite content in sinter increases,while the acicular calcium ferrite content decreases.Accordingly,the sinter yield and tumble index decrease with excessive H_2O(g) content.To guarantee the yield and quality of sinter,the favourable H_2O(g) content in circulating flue gas should be controlled to be less than 6%.     

Analysis by multiphase multicomponent model of iron ore sintering based on alternative steelworks gaseous fuels

Abstract

This paper presents the numerical simulation of the technology of gaseous fuel utilisation for iron ore sintering. The proposed methodology is to partially replace the solid fuel by steelworks gases. A multiphase mathematical model based on transport equations of momentum, energy and chemical species coupled with chemical reaction and phase transformations was proposed to analyse temperature distributions of the process. A base case of actual industrial operation of a large sintering machine was monitored with thermocouples inserted into the sinter bed to validate the model. The model was used to predict four cases of fuel gas utilisation: feeding from N01 to N15 wind boxes with blast furnace gas (BFG); natural gas (NG); coke oven gas (COG); and a 50–50 mixture of BFG and COG. The model predictions indicated that for all cases the sintering zone is enlarged and the solid fuel consumption could be decreased.     

复合气体介质烧结的节能减排技术开发与应用

 烧结烟气排放量大、污染物种类多,是钢铁工业节能减排的重点工序。阐述了气体介质变化对烧结的影响规律,介绍了多种基于复合气体介质烧结的减排新工艺和新技术。针对烧结烟气和热废气循环利用,开发了区域选择性烟气循环工艺,在不影响烧结指标前提下实现烟气减量和污染物减排;开发了环冷机热废气提质-循环烧结工艺,提高了余热利用效率,并减少了冷却废气无组织排放。揭示了多种类型的富氢燃气喷吹对烧结的影响规律,开发了富氢燃气梯级喷吹技术,改善了烧结料层的热量分布状态,降低了固体燃耗和污染物排放。探明了烧结料面喷吹水蒸气对烧结指标的影响,获得了水蒸气喷吹的适宜区间和喷吹方法,实现了CO的减排。提出了载能复合气体介质烧结协同减排技术路线,以燃气和蒸汽复合气体为例,探明了两类气体在烧结料面的适宜耦合喷吹方式,取得了更大程度的烧结提质、节能、减排效果。     

Batch drying in sintering

An adapted mathematical model of sintering permits analysis of the thermophysical characteristics of batch drying, primarily in the main sintering period. Over the whole length of the sintering machine, most of the bed volume corresponds to equilibrium moisture content, which may be higher or lower than the initial value. The temperature of the gas entering the drying zone is calculated, and its dependence on the parameters of the batch and gas is determined.     

Gas dynamics of the initial sintering bed

The gas dynamics of the sintering bed is analyzed. The proposed method for calculating the gas-dynamic parameters of sintering permits quantitative estimation of the gas permeability of the bed on the basis of data regarding the properties of the initial batch. This provides the basis for more profound analysis of the processes that accompany the sintering of iron ore.     

烟气循环烧结过程料层温度及NOx排放模拟模型

 为了研究烟气循环条件影响料层的热状态及减排机理,依据烟气循环烧结过程主要反应的热力学和动力学、气-固传热规律以及气体流体力学,建立了烟气循环烧结料层温度及NO_x排放的数值模拟模型。试验验证结果表明,模型计算的料层温度、气体组分(O₂、CO、NO)等与试验检测值吻合较好,料层温度及NO排放浓度相对误差在±5%以内;根据模拟模型分析可知,烟气循环烧结中影响NO排放的主要因素是烟气循环中O₂和CO浓度,随着O₂浓度的降低和CO浓度的上升,燃料氮氧化反应速率明显下降,NO-CO还原反应速率升高,烟气中NO平均排放浓度降低。     

Dynamic process modelling of iron ore sintering

A mathematical model was developed for the iron ore sintering process considering all the major thermochemical phenomena in the system, assuming both the static and moving bed configurations. The model predicted a large number of parameters pertinent to the sintering process including the temperatures of the gas and solid, concentration of various species, amount of solid melted etc. The results were tested against the data existing in literature, and a limited number of pot tests conducted in a pilot plant. Despite high complexity of the problem, the agreement between the experimental and simulated data was reasonably good.     

Influence of O2 Content in Circulating Flue Gas on Iron Ore Sintering

 Circulating flue gas can reduce the emission of flue gas, and furthermore, it can reuse the waste heat effectively in the sintering process. Compared with conventional sintering, O2 that gets through the sintering bed decreases because of substituting circulating gas for air. The influences of O2 content on sintering process are studied through simulating the flue gas circulation sintering with artificial gas. It shows that, with the reducing of O2 content in circulating gas, the combustion speed of fuel decreases and incomplete combustion degree increases, which makes the flame front fall behind the heat front and reduces the heat utilization efficiency of fuel. The ultimate result is that the temperature of sintering bed decreases and the liquid phase reduces. In addition, the reducing atmosphere is strengthened because of flue gas circulation, which makes the magnetite increase yet calcium ferrite reduce gradually. Because the content of calcium ferrite with good strength reduces, the sinter yield and tumble strength decrease. To ensure the sinter index, the favorable O2 content of circulating flue gas is no less than 15%.     

分层供热富氢烧结关键技术探索与研究

 中国提出2030年碳达峰、2060年碳中和的“双碳”战略以缓解温室效应带来的环境问题。钢铁是仅次于火电的国内第二碳排放大户,作为钢铁行业中的核心环节,烧结工序的碳减排已是必然趋势。常规烧结工艺中,料层中固体颗粒燃料难准确满足“自蓄热效应”要求的“上多下少”的分布要求,导致料层内部供热不均、成矿质量差、能效低下,且易出现微观局部还原性气氛,对烧结成矿和烟气中CO增多造成负面影响,制约了烧结节能减碳水平的提升。对此,作者研究了燃料形态、燃料分布对烧结的影响规律,提出了“分层供热富氢烧结”理念,阐述了厚料层烧结条件下料层上、中、下各层不同的气固组合供热方法,即顶层依靠富氧点火耦合固体燃料供热、上中层依靠富氢燃气喷加耦合固体燃料供热,下层依靠水蒸气喷加耦合固体燃料供热,同时探明了对应该方法的分层供热低碳烧结机理,详细阐述了富氧点火耦合固体燃料顶层供热、富氢燃气喷加耦合固体燃料中上层供热、水蒸气喷加耦合固体燃料下层供热等关键技术及其技术效果,并对应用上述技术可能出现的烧结过湿层恶化问题提出了解决办法。通过这些技术的集成应用,可以大幅降低烧结工序能耗,减少烧结工序碳消耗、碳排放及其他污染物排放,并改善烧结矿质量。     

烧结工序流分析及评价

在钢铁形势日趋严峻的当下,节能减排是烧结厂得以生存的必由之路。基于物料平衡和热平衡原理建立的烧结工序流评价模型,可以从宏观和微观两方面反映出烧结工序的流走向,从而挖掘其节能潜力所在。对某一典型烧结厂的流分析研究结果表明,该烧结过程固体燃料和混合料的分别占收入的73.59%和17.28%,热烧结矿的物理、烧结机损和烟气的热量分别占支出的47.42%、30.34%和21.63%,该烧结工艺的普遍效率和目的效率分别为69.66%和48.02%,具有较大的节能潜力。可以采用优化配矿、厚料层烧结、烟气循环烧结、余热发电等技术措施来提高效率,最终实现烧结工序节能减排的目的。     

Modeling the discontinuous liquid flow in a blast furnace

This article presents a mathematical model to describe the discontinuous flow of an isothermal liquid in packed beds, simulating in part the flow condition in and below the blast furnace cohesive zone. The model is developed based on a force balance approach to describe the discrete liquid flow and a stochastic treatment to take into account the complex packing structure. The interaction between gas and liquid flows has also been included in the governing equations, so that the localized liquid flow in a packed bed can be modeled with or without gas flow. The difference between the microscopic and macroscopic approaches is discussed, and it is argued that at this stage of development, liquid flow modeling should be conducted at the macroscopic level. Techniques for numerical solution are provided. The validity of the proposed model is demonstrated by comparing model predictions with measurements obtained using a two-dimensional cold model apparatus under different gas and/or liquid flow conditions.