【作者】 张琦；

【导师】 蔡九菊；

【作者基本信息】 东北大学 ， 热能工程， 2008， 博士

【摘要】 钢铁生产过程是复杂的铁—煤化工过程,洗精煤、高炉喷吹用煤等含碳能源经过转换、回收、使用等环节直到最终二氧化碳排放形成能量流,推动铁素流从天然资源到钢铁产品的转换,其中,碳素流是能量流的主体。煤气是碳素流的主要组成部分,是钢铁联合企业中重要的二次能源,占企业能源消耗总量的30%左右。所以,正确地认识钢铁联合企业中煤气供需关系的变化规律,科学地规划、实施煤气的生产、储存、分配和利用,特别是富余煤气的缓冲使用策略,对优化利用钢铁联合企业的煤气资源,降低吨钢能耗、减少二氧化碳排放都有十分重要的意义。论文系统地研究了钢铁联合企业煤气的生产与利用及煤气的供需关系变化规律；建立了煤气资源在若干用能设备上的优化分配以及富余煤气在煤气柜与自备电厂锅炉等缓冲用户的动态优化分配数学模型,为钢铁联合企业煤气合理利用、优化分配提供理论依据和分析工具。主要研究内容如下：(1)根据典型高炉—转炉生产流程碳素流的输入、转换、耗散和排放过程,剖析了炼铁、炼焦和炼钢等生产工艺及高炉煤气、焦炉煤气和转炉煤气的回收与利用。从原燃料条件、热工操作、回收工艺及空气(煤气)预热、物料热装热送等方面分析了影响煤气回收与利用的各种因素。论述了钢铁联合企业煤气富余的原因以及富余煤气的发电方式,分析了热电联产的节能效果,提出富余煤气利用的基本原则,并展望了焦炉煤气制氢、生产甲醇和直接还原铁等再资源化途径。(2)建立了钢铁联合企业煤气供需预测模型,对回收量、需求量和富余量的预测表明,影响企业吨钢煤气产率、吨钢煤气燃耗及煤气富余量的因素主要是各工序的单位煤气产率、单位煤气燃耗和钢比系数。研究了钢铁联合企业煤气供需关系变化规律,提出煤气回收与利用水平的评价指标,主要有煤气回收率、煤气在用能设备的热能转换效率、煤气热电转换效率和煤气综合利用率；分析了煤气回收与利用对吨钢综合能耗的影响,研究结果表明,降低企业吨钢综合能耗的措施主要有：①采用蓄热式燃烧、空气(煤气)预热等技术提高煤气的利用效率,降低用能设备单位煤气消耗；②采用干法除尘等技术完善回收工艺,增加煤气回收率；③采用燃气—蒸汽联合循环发电机组高效利用富余煤气,提高煤气热电转换效率；④建设能源管理中心,提高煤气管理水平,减少或消除煤气放散损失。分析了钢铁联合企业富余煤气利用与“只买煤不买电”能源模式的相互关系,探讨了不同规模钢铁联合企业的煤气利用和“只买煤不买电”模式的实现方案。(3)研究了钢铁联合企业用能设备煤气的互换性和合理热值问题,根据煤气在不同设备上使用效率存在差异,用燃料利用系数与用能设备燃料改变前后的单位燃耗为基本参数,以用能设备能源需求、工艺要求、能源介质平衡等为约束条件建立了钢铁联合企业煤气优化分配模型,旨在对企业自产煤气进行最优分配,使能源消耗量最小。研究表明,煤气的替换不能简单按照不同煤气等价热量进行,而应该综合考虑煤气的数量和质量；合理热值的确定将煤气与用能设备的热工操作参数紧密结合,降低了加热过程中的传热火用损失；单品种煤气应优先使用,余量再并网,以减少高炉煤气、焦炉煤气混合过程的火用损失及管道、混合加压设备的投资费用。本文提出的煤气优化分配模型为钢铁联合企业制定长、中、短期煤气规划,确定最佳煤气使用方案,进行计划预测和系统分析提供了有利工具。(4)引入惩罚函数方法,建立了富余煤气在煤气柜与自备电厂等缓冲用户的动态优化分配模型。该模型充分发挥了煤气柜、自备电厂锅炉对富余煤气的缓冲作用,提高煤气发电效率,使企业煤气放散或不足量最小。同时,改变了以往煤气柜只起保安作用、富余煤气利用以牺牲发电设备的效率为代价的做法。研究结果表明：根据自备电厂锅炉的容量、效率和使用燃料的种类,使煤气在若干效率不同的锅炉间得到合理分配且煤气柜的柜位在安全范围内；过剩或不足的煤气量通过改变煤气柜、自备电厂锅炉等缓冲用户的缓冲量得到调整,充分、高效地利用了钢铁生产中的富余煤气资源并减少了煤气放散。(5)针对鞍钢和迁钢的实际生产情况和煤气资源供需状况,分别应用煤气优化分配模型和富余煤气在缓冲用户的动态优化分配模型。根据鞍钢不同的生产工况、部分工序设备改造后的煤气资源供需变化,给出了煤气资源优化分配、高效利用的指导方案。结果表明：鞍钢应用优化分配模型后,降低了各工序用能设备的煤气发热值和单位产品煤气消耗；同时,假设富余煤气全部用于发电,且热电效率为37%,可降低吨钢综合能耗37.59kgce/t钢；针对新1#3200m3高炉休风、1780热轧生产线检修、新四炼焦一座6m焦炉检修等生产工况下煤气的优化分配表明,鞍钢煤气系统节能还有很大潜力,在满足生产要求和自备电厂煤气缓冲的范围内,尚有8.32万m3/h的焦炉煤气外供；对迁钢富余煤气进行优化分配后,富余的煤气在煤气柜和自备电厂锅炉中合理调配,使锅炉在适当的时候变换燃料且煤气柜的柜位在安全范围内,充分利用煤气资源,减少煤气放散。更多还原

【Abstract】 The process of steel producing is a typical iron-coal chemical process:the coal energy such as clean coal and coal for injection change to CO2 by conversion tache, recovery tache and using tache, producing iron and steel products based on consumption of iron ore and coal. And in this way the energy flow is formed, in which the coal flow is the main part. Byproduct gases is main parts in carbon flow, and the important secondary energy in iron and steel works, taking part of 30% in total energy consumption. So how to recognize the changing law of gas supply and demand relations in iron & steel complex, to plan the production, stock, distribution and utilization of gas, especially the buffer utilization strategy for the residual gas, for using the gas rationally, reducing the energy consumption per ton steel and CO2 emission is very meaningful. This paper studies the law of gas production and utilization, and that of gas supply and requirement; builds the gas optimization and distribution model for several energy using equipments; constructs the gas dynamic optimization and distribution model for the residual gas distribution between gas holders and boilers in the power plant. The models offer the theoretical basis and analyzing tools for the rational utilization and optimization distribution of gases. The main contents of this paper are as follows:(1) Tracking the conversion and dissipation process of carbon element flow in iron and steel production, the byproduct gases recovery and utilization analysis indicate that the carbon element flow change under the certain amount of the total carbon element flow in iron and steel manufacturing flow. The producing process and BFG, COG and LDG recovery and utilization are analyzed. The factors of influencing the gas recovery and utilization are indicated:original fuel condition; thermal operation conditions; recovery process; equipment levels; preheated combustion medium et al. The three modes of gases for power are expounded and the rules of residual gas utilization are put forward. Gas regeneration utilization and route are viewed.(2) Gas supply and demand forecasting model is established in iron and steel works, the factors influencing the gas generation, gas consumption and residual gas amount per steel are analyzed, unit gas generation and gas consumption per product and steel ration of each process take the dominating factors. The relation of gas supply and demand is analyzed and the evaluating indexes of gas recovery and utilization are put forward, such as gas recovery rate, gas thermal conversion efficiency, gas thermal-electricity conversion efficiency and gas integration utilizing efficiency. The influence of gas recovery and utilization on energy consumption per steel is analyzed and the measures of reducing energy consumption per steel of iron and steel works from gas utilization viewpoint is indicated:①reducing gas consumption of using energy equipments through improving gas utilizing efficiency by heat regenerative technique;②perfect the gas recovery process with dry dust technique;, increasing gas recovery ratio;③utilizing residual gas efficiently, enhancing gas thermal-electricity conversion efficiency with CCPP;④strengthening gas management level, decreasing or eliminating gas release loss by constructing EMC. The model of "Buying only coal and no purchasing electricity" is proved and the gas supply-demand model are analyzed in different steel scale iron and steel works under residual pressure and heat power levels.(3) Exchangeability of fuels in facilities and reasonable heat value of gases are studied in iron and steel works, and the byproduct gas utilization and distribution model for least energy consumption which is restricted by energy demand, process requirement and energy medium balance is set up based on fuel utilization coefficient and unit fuel consumption of fuel changeable, according to the difference of fuel using efficiency in different equipments. Gas quantity and quality are considered comprehensively in interchangeability of fuel gases; reasonable gas heat values makes gas utilization and equipment thermal operation parameter combine closely for decreasing the heat transfer exergy lose in the process of heating; the viewpoint of priority using single variety gas and remainder inputting gas net is put forward for reducing the exergy lose in mixing process of BFG and COG, investment charge of pipelines, mixing and pressurized station equipments. The model is feasible and available for making gas utilization plan of long, middle and short term and confirming optimal gas consumption project by improving the gas utilization efficiency and thermodynamics grade.(4) The residual gas dynamic distribution model in gas holder and power station is set up using punishing function, and the status of gas holder only for safety and reducing the efficiency of power station by using abundant byproduct gases is changed. The buffer by gas holder and boilers in power station improves gas and power utilization efficiency, and reduces gas emission. The efficiency, capacity and available fuel of boilers, surplus and deficient gas amount are adjusted by gas holder and power station, the gases resource is optimized and distribution, the gas emission is reduced.(5) The gas optimizing distribution model and residual gas optimizing utilization model are used in different iron and steel works-An steel works and Qian Steel respectively. The plans of gas utilization and optimizing distribution efficiently are put forward on the gas supply and demand conditions of different producing status. It is indicated that the gas heat values and gas consumption per ton product of different energy using equipments decrease. If the residual gas using for power and power efficiency is 37%, the energy consumption per steel will decrease 37.59 kgce/t steel. It is indicated that the potential of energy saving in the gases system of An Steel is very high when the blast furnace stops running, or 1780 rolling producing line is examined, or the 6m coke oven is examined. In the current status it is 83.2 thousand cubic meter per hour coke oven gas for sale under the producing demand and gas. Residual gas is optimizing distribution between gases holders and boilers in power station in Qian Steel. After optimization, the gas emission decreases and operation fee is saved when gas holder is in safety zone and fuels are changed in boilers correctly.更多还原