烧结余热梯级利用及脱硫脱硝一站式解决方案

结合某钢铁厂430 m2烧结机及环冷机的烟气气氛和温度分布情况，提出烧结烟气的脱硝－余热利用－脱硫一站式解决方案。根据烧结烟气的气氛和温度将烧结烟气划分成3部分：非脱硫脱硝系烟气(115℃)、脱硫脱硝系烟气(86℃)和脱硫系烟气(360℃)。其工艺流程为，首先利用冷却机中温段热空气(150℃)和脱硫系烟气以及其他外部热源对脱硫脱硝系烟气进行加热，使脱硫脱硝系温度达到270~320℃后进入脱硝装置，采用低温NH3-SCR法进行脱硝；其次将270~320℃已脱硝的烟气通入余热锅炉内生产蒸汽，产生的蒸汽一部分用于烧结矿料的预热，其余部分并入蒸汽管网；然后将160℃的锅炉尾部烟气与换热后的脱硫系烟气通入浓缩塔中，与来自脱硫塔的硫酸铵溶液接触换热，烟气冷却至最佳脱硫温度70~80℃后进入脱硫塔内，采用湿式氨法脱硫技术进行脱硫，与此同时硫酸铵溶液因水分的蒸发而浓缩，烟气的余热进一步得到有效利用。本工艺可使烧结系统烟气的余热得到最大限度的回收以及烟气排放得到有效控制。

One-stop solution of cascade utilization of waste heat recovery,desulfurization and denitrification in the sintering system

Combined with the flue gas atmosphere and temperature distribution of 430 m2 sintering machine and ring cooler of a steel plant,a one-stop solution for denitrification—utilization of waste heat—desulfurization from sinte-ring flue gas was proposed.According to sintering flue gas atmosphere and temperature distribution,sintering flue gas is divided into three parts:non desulfurization and denitrification flue gas (1 1 5℃),desulfurization and denitri-fication flue gas (86℃),and desulfurization flue gas (360℃).The process is as follows.Firstly,the hot air of the cooler (150℃),desulfurization flue gas and other external heat source were utilized to heat the desulfurization and denitrification flue gas.When the temperature of desulfurization and denitrification flue gas reached 270-320℃,it entered the denitrification device in which low temperature NH3-SCR method was adopted.Secondly,the flue gas with temperature of 270-320℃ was pumped into the waste heat boiler to produce steam.Part of the steam was used to preheat the sinter material,and the rest was incorporated into the steam network.After that,the exhaust gas of boiler and desulfurization flue gas (160℃)was pumped into the concentrating tower,so as to exchange heat with (NH4 )2 SO4 from the concentrating tower.When the exhaust gas cools down to 70-80℃ which is the best temperature for desulfurization,the exhaust gas was pumped into the desulfurization tower in which wet ammonia desulfurization method was used.At the same time,the solution of (NH4 )2 SO4 was concentrated due to the evap-oration of water;thus,the waste heat of exaust gas could be further utilized.This technical process makes best use of the waste heat of exhaust gas and makes sintering flue gas meet the emission standards in the sintering system.