过程工业尾气封闭循环原理与应用(Ⅱ):绿电制硝酸  

Principles and application of enclosed exhausts cycling for process industry(Ⅱ):Production of nitric acid from green power

作　　者：朱家骅[1] 卢蔚 彭玉凤 李季[1] ZHU Jiahua;LU Wei;PENG Yufeng;LI Ji(School of Chemical Engineering,Sichuan University,Chengdu 610065,Sichuan,China)

机构地区：[1]四川大学化学工程学院,四川成都610065

出　　处：《化工学报》2021年第10期5265-5272,共8页CIESC Journal

基　　金：国家科技支撑计划项目(2013BAC12B01)。

摘　　要：针对传统氨-空气氧化制硝酸工艺尾气NO_(x)和N_(2)O排放,通过化工过程自由能耗散比模型分析指出污染物扩散所致环境自由能耗散可达产品加工有效自由能的66.2%。为此提出绿电制硝酸(GPtNA)尾气封闭循环新工艺,将电解水制氢/氧和空分制氧/氮两个单元耦合嵌入合成氨与硝酸工艺圈,以电代碳,提供绿色氢、氧、氮资源;与传统硝酸工艺相比,吨产品(HNO3100%)减碳0.356 t、CO_(2)减排1.31 t、回收NO_(x)与N_(2)O各1.01~1.70 kg,对硝酸工业减碳降污具有重要意义。新工艺开发依托成熟的合成氨、硝酸与空分技术,利用绿电制氢电耗4.3kW·h/m^(3)等前沿成就,硝酸产品理论电耗为2560 kW·h/t、其成本可与传统硝酸工艺理论氨耗269.8 kg/t相竞争,当可再生(水、风、光)电价低于0.22 CNY/(kW·h),GPtNA工艺具有资源、环境和经济性全面竞争优势。Based on a model analysis of free energy dissipation in chemical processes it is pointed out that the ambient air quality decline,induced by dispersion of NO_(x) and N_(2)O emission from traditional ammonia/air oxidation nitric acid(AAtNA)process,accounted as environment loss of free energy will reach 66.2% of that effectively consumed in production.Hence a new process of green power to nitric acid(GPtNA)is proposed for elimination of pollution source by enclosed exhaust cycling.For the purpose of carbon replacement by power,the units of water electrolysis and air separation are coupled into the loops of high pressure catalytic ammonia synthesis and dualpressure catalytic oxidation/absorption nitric acid to supply green hydrogen,oxygen and nitrogen sources.Compared with AAtNA process,0.356 t carbon consumption can be avoid therefore 1.31 t CO_(2) emission abated,plus 1.01—1.70 kg NOxand 1.01—1.70 kg N_(2)O recovered for per ton nitric acid(100%HNO3)produced by GPtNA process,meaningful to carbon reducing and pollution abatement for nitric acid industry.Based on the mature industrial technologies of ammonia,nitric acid and air separation,the new process development is also benefited from the frontier achievement of green power to hydrogen.Under the current available power-hydrogen efficiency of 4.3 kW·h/m^(3),a theoretic power consumption of 2560 kW·h/t for GPtNA process can be competitive to the cost of theoretic ammonia consumption of 269.8 kg/t for AAtNA process under certain power/ammonia price ratio.When the renewable(water,wind,light)electricity price is lower than 0.22 CNY/(kW·h),the GPtNA process has a comprehensive competitive advantage in resources,environment and economy.

关 键 词：过程系统 硝酸工艺 污染控制 封闭循环 二氧化碳减排 绿电制氢 

分 类 号：TQ021.4[化学工程] X78[环境科学与工程—环境工程]