铁矿石烧结中混合料特性对火焰烽面与烧结性能的影响机理研究

doi:10.11949/0438-1157.20190001

摘要/Abstract

摘要：

通过中试规模烧结杯试验和综合烧结模型，将返矿平衡和非平衡条件相结合，研究了混合料特性（烧结碱度、焦炭和水分添加量）对火焰烽面特性和烧结性能的影响机理。模拟研究涉及多种烧结条件下的125个烧结杯工况。为揭示火焰烽面区域中熔体生成与凝固行为，使用FactSage软件进行化学热力学模拟并建立了更完善的熔化和凝固子模型。模拟与试验研究表明，随着碱度和焦炭添加量的变化，火焰烽面速度、成品率、焦比和利用系数会出现局部最大或最小值。在本文烧结条件下，最大利用系数工况为碱度2.0、水分7.7%、焦炭6.4%。最小焦比工况为碱度2.0、水分6.5%、焦炭6.4%。最小焦比和最大利用系数的条件并不相同，而最终烧结操作取决于每个烧结厂的控制目标。

关键词: 焦炭燃烧, 火焰烽面, 填充床, 传热, 数值模拟

Abstract:

In this paper, the pilot-scale sintering cup test and the comprehensive sintering model were combined to analyze the effects of mixture characteristics (sintering alkalinity, coke and moisture addition) on flame kneading properties and sintering properties. Previously developed and validated sintering sub-models have been integrated in this work. Simulations were carried out based on 125 cases simulating a wide range of sintering conditions. Thermochemical modelling using FactSage provided useful information to improve the melting and solidification sub-model and provide greater insights into the state of the material in the flame front. Modelling studies showed that the maximum or minimum values of flame front speed, yield, coke rate and productivity appear when the basicity and coke addition change continuously. Under the sintering conditions of present work, the condition for maximum productivity is basicity 2.0, moisture level 7.7%, coke level 6.4%. The condition for minimum coke rate is basicity 2.0, moisture level 6.5%, coke level 6.4%. Obviously, the optimum productivity and coke rate conditions are different. The actual operating conditions will depend on the objective of a sinter plant.

Key words: coke combustion, flame front, packed bed, heat transfer, numerical simulation

中图分类号:

TF 58

赵加佩, 周昊, 周明煕, 王甫, 袁金良. 铁矿石烧结中混合料特性对火焰烽面与烧结性能的影响机理研究[J]. 化工学报, 2019, 70(8): 3177-3187.

Jiapei ZHAO, Chin Eng LOO, Hao ZHOU, Mingxi ZHOU, Fu WANG, Jinliang YUAN. Effect of sinter mix properties on the flame front properties and iron ore sintering performance[J]. CIESC Journal, 2019, 70(8): 3177-3187.

图/表 13

表1 基础碱度和高碱度混合料化学成分

Table 1 Sinter mix chemistry for BASE and HB cases

成分	质量分数/%
成分	基础碱度(碱度值1.8)	高碱度(碱度值2.2)
Fe₂O₃	83.36	81.40
CaO	8.78	10.74
SiO₂	4.88	4.88
Al₂O₃	1.48	1.48
MgO	1.50	1.50

图1 FactSage模拟得出的两种碱度下熔体量β随温度T s的变化规律(基础碱度BASE和高碱度HB情况),图中两条曲线表示根据本文熔化和凝固模型[式(3)]所拟合得到的结果)

Fig.1 Variation of melt fraction β with temperature T s for the examples of two basicity levels (BASE and HB) predicted by thermochemical modelling with FactSage(The two lines indicate the results fitted to the melting and solidification model according to Eq. (3))

表2 返矿平衡烧结杯试验条件[10,11]

Table 2 Summary of conditions for return fines balanced sinter pot tests[10,11]

参数	数值
床高(含铺底料层)/mm	550
铺底料层厚度/mm	30
烧结杯截面积/m²	0.09
床点火温度/℃	1200
点火时间/s	90
点火负压/kPa	6
烧结负压/kPa	16
落下强度试验(2m高)/次	4
焦炭添加量/%(dob^②)	6.00, 6.25^①, 6.50
碱度(CaO/SiO₂)	1.5, 1.8^①, 2.1
混合料水分含量/%(tmb^③)	6.7, 7.2^①, 7.6

表3 返矿不平衡的模拟工况条件

Table 3 Summary of conditions for simulation cases with constant return fines level

参数	数值
床高(含铺底料层)/mm	600
铺底料层厚度/mm	30
烧结杯截面积/m²	0.088
床点火温度/℃	1200
点火时间/s	90
点火负压/kPa	6
烧结负压/kPa	16
落下强度试验(2m高)/次	4
返矿用量/%(dob^②)	32.4
焦炭添加量/%(dob^②)	5.9, 6.15, 6.4^①, 6.65, 6.9
碱度(CaO/SiO₂)	0.8, 1.4, 2.0^①, 2.6, 3.2
混合料水分含量/%(tmb^③)	6.5, 6.8, 7.1^①, 7.4, 7.7

图2 返矿平衡条件下烧结杯试验的返矿量、成品率、火焰烽面速度、利用系数和焦比随碱度变化结果（模型预测结果也示于图中）

Fig.2 Sinter pot test results of return fines level, yield, FFS, productivity and coke rate at increasing basicity levels（MT, β mean, yield, FFS, productivity and coke rate predicted by the model are also shown）

图3 返矿平衡条件下烧结杯试验的返矿量、成品率、火焰烽面速度、利用系数和焦比随焦炭添加量的变化结果（模型预测结果也示于图中）

Fig.3 Sinter pot test results of return fines level, yield, FFS, productivity and coke rate at increasing coke addition levels(MT, β mean, yield, FFS, productivity and coke rate predicted by the model are also shown)

图4 返矿平衡条件下烧结杯试验的返矿量、成品率、火焰烽面速度、利用系数和焦比随水分添加量的变化结果（模型预测结果也示于图中）

Fig.4 Sinter pot test results of return fines level, yield, FFS, productivity and coke rate at increasing mix moisture levels(MT, β mean, yield, FFS, productivity and coke rate predicted by the model are also shown)

图5 模型计算所得MT随碱度、焦炭和水分添加量的变化规律

Fig.5 Variation of MT with basicity, coke and mix moisture levels

图6 模型计算所得FFS随碱度、焦炭和水分添加量的变化规律

Fig.6 Variation of FFS with basicity, coke and mix moisture levels

图7 模型计算所得β mean随碱度、焦炭和水分添加量的变化规律

Fig.7 Variation of β mean with basicity, coke and mix moisture levels

图8 模型计算所得成品率随碱度、焦炭和水分添加量的变化规律

Fig.8 Variation of yield with basicity, coke and mix moisture levels

图9 模型计算所得焦比随碱度、焦炭和水分添加量的变化规律

Fig.9 Variation of coke rate with basicity, coke and mix moisture levels

图10 模型计算所得利用系数随碱度、焦炭和水分添加量的变化规律（图中黑点位置为最大利用系数参数位置）

Fig.10 Variation of productivity with basicity, coke and mix moisture levels for five moisture levels (6.5%—7.7%)

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