钢铁流程系统的能耗排放特征及其广义热力学优化

Energy Consumption,Emission Characteristics and Generalized Thermodynamic Optimization of Iron & Steel Process Systems

钢铁生产流程能源配置技术落后、集成度低。为在整体上实现钢铁生产流程的节能减排,该研究围绕解决对应的关键科学问题"钢铁生产流程物流—能流—环境作用机理及其多目标集成优化理论",在工序模块、单体组件和功能子系统层面开展了前期研究,为实现全流程仿真和优化奠定了基础。主要包括:(1)提出绝热过程火积耗散极值原理,对等温和对流辐射传热边界条件下6种不同形状的加热炉绝热层进行构形优化,得到整体绝热性能最优的绝热层构形。(2)提出"广义构形优化"理论,将火积理论引入板坯连铸凝固传热过程的研究中,分别考虑热损失率和火积耗散率目标,得到同时兼顾板坯内部温度梯度和表面温度梯度的二冷区水量分配最优构形。(3)运用系统动力学原理,构建烧结、炼铁工序的铁素流动态模型,获得不同返回物质流情况下的铁素流整体宏观动态特性。(4)基于"运动参考坐标系",建立烧结矿冷却过程二维非稳态连续模型,获得相应的流场、压力场、温度场特性。(5)基于非线性规划理论建立高炉炼铁过程优化模型,分别以炉腹煤气量指数相关联的高炉利用系数和碳排放为优化目标,研究炉腹煤气量指数等参数和高炉喷吹煤粉、喷吹塑料对优化结果的影响。(6)建立中厚钢板轧后冷却过程数学模型,明晰设计参数和冷却方式对钢板表面和终冷温度的影响。(7)构建以火用为表征参数的特征化模型,以高炉-转炉炼钢、电炉炼钢过程为例,分析钢铁生产流程资源和能源交互作用的耦合关系。(8)建立钢铁生产流程分析模型,计算典型钢铁企业碳、氮、硫等元素向多形态废弃物转换及排放的数量和结构。计算钢铁生产过程的环境负荷数据,得到我国典型钢铁生产过程资源、能源消耗和CO2、SO2、NOx、CO、CH4等排放清单。(9)运用各层次单元之间的物流、能流关系及流程网络重构技术,开发工序能质平衡计算与流程仿真软件。(10)构建具体到工序层次的钢铁生产、加工和消费的全生命周期物质流模型,分析不同情景下中国废钢增长趋势对钢铁流程的结构演变及其能耗和排放的影响。(11)研究铸轧区段生产组织及钢坯热送热装等流程节能技术,提出节能技术优化组合概念,探讨关键技术之间的关联关系和优化组合模式。(12)建立12种钢厂余能余热驱动简单和复杂、闭式和开式燃气轮机动力装置、热电联产装置和热电冷联产装置的经典热力学和有限时间热力学模型并进行性能分析和优化;建立两种钢厂低温余热驱动半导体热电发电机模型并进行数值模拟。明晰各系统的热力学整体特性及基本优化关系,获得各个工序余能余热驱动热力过程和循环的最佳设计方案。

In order to achieve the overall objective of energy conservation and emission reduction of iron and steel production process, this subject focused on the key scientific problem of “the action mechanism among material flow, energy flow and environment and the corresponding multi-objective integration optimization theory in iron and steel production process” and performed preliminary study as follows： （1）The entransy dissipation extremum principle for thermal insulation process is proposed and applied into the constructal optimizations for insulation layers of reheating furnace wall. （2）The theory of generalized constructal optimization is proposed and applied to search the optimal water flow distributions of secondary cooling zone for slab continuous casting. （3）The system dynamic models for iron-flow of sintering and ironmaking are established and the overall macroscopic dynamic characteristics of iron-flow are obtained. （4）The gas flow, pressure and temperature fields of the sinter ore cooling process are obtained based on a 2D transient consecutive model. （5）The optimizations of blast furnace ironmaking process are performed with blast furnace utilization coefficient and carbon emission as objectives. （6）The effects of design parameters and cooling methods on surface temperature and final cooling temperature are analyzed for cooling process after plate rolling. （7）The coupling relationship of the interaction between the resources and energy of iron and steel production process is analyzed based on an exergy characterized model. （8）The quantity and structure of the conversion and emissions to polymorphic waste of carbon, nitrogen, sulfur and other elements in typical companies are calculated based on the analysis model for iron and steel production process. （9）The software package for energy and material balance and process simulation are developed. （10）The effects of the growth trends of steel scrap on routes evolution, energy consumption and emissions of the production process are analyzed based on the material flow model for entire iron and steel life-cycle. （11）The concept of optimal combination of energy-saving technologies is proposed and the correlation and optimal combination mode among key technologies are discussed. （12）The performance analyses and optimizations for 14 classical and finite time thermodynamic models of energy conversion processes and cycles driven by residual energy in iron and steel plants have been performed.