工业烟气中CO_(2)直接用于增施气肥的流动及扩散特性

Flow and Diffusion Characteristics of CO_(2)in Industrial Flue Gas Applied Directly to Gas Fertilizer

工业烟气中的CO_(2)浓度较低,并且含有不同污染物,能否直接用作增施气肥存在一定的不确定性。为研究将工业烟气中CO_(2)直接用于农业生产中增施气肥的可行性,对工业烟气排放后的烟气特性、CO_(2)组成、污染特性进行了分析和评估。基于CFD数值模拟技术,对工业烟气在大棚内的CO_(2)扩散特性进行了模拟分析。研究结果表明,工业烟气中含有不同的污染物成分可能会对大棚内的环境空气质量产生影响,需经过合理评估并采取适当措施后方可满足农业生产的要求。基于燃煤电厂排放的烟气特点,在CO_(2)吸收速率为5×10^(-8)m^(3)/s、烟气稀释倍数为100,控制进入大棚内的SO_(2)、NO_(2)、Hg、HF和PM等污染物浓度达到15 mg/m^(3)、8 mg/m^(3)、5μg/m^(3)、0.2 mg/m^(3)和7.5 mg/m^(3)时,可实现大棚内的污染物浓度达到环境空气质量标准的一级标准(GB 3095—2012),并且CO_(2)浓度满足植物生长的浓度要求。不同入口布置方式对大棚内的CO_(2)浓度影响较大,采用两边和中间同时布点的方案可以较好实现CO_(2)浓度在大棚内的均匀性要求。因此,工业烟气中的CO_(2)直接用于农业生产具有可行性,但在实际应用中,应结合烟气中的CO_(2)浓度、植物的吸收速率、CO_(2)喷入位置、稀释倍数和污染物浓度进行综合评估,并应用于农业生产。

CO_(2)concentration in industrial flue gas is low and contains different pollutants,so it is uncertain whether it can be directly used as gas fertilizer.In order to study feasibility of directly using CO_(2)form industrial flue gas for gas fertilizer agriculture,flue gas characteristics,CO_(2)composition and its pollutants on agricultural production were analyzed.Based on CFD numerical simulation technology,diffusion and distribution characteristics of CO_(2)were simulated and analyzed.Results showed that high concentration of CO_(2)from power,steel,cement or other industrial flue gases could be used for promoting plant growth.Different pollutant components in industrial flue gas may affect ambient air quality in greenhouses,so it only can be used for carbon-rich agriculture after reasonable evaluation or suitable measures were taken.Based on characteristics of flue gas emitted from coal-fired power plants,when CO_(2)absorption rate was 5×10^(-8)m^(3)/s and flue gas was diluted by 100 times,moreover,control inlet concentration of SO_(2),NO_(2),Hg,HF,PM to 15 mg/m^(3),8 mg/m^(3),5μg/m^(3),0.2 mg/m^(3)and 7.5 mg/m^(3),environmental air quality could be controlled to meet A-level standard of GB 3095—2012.At this point,concentration of CO_(2)also met concentration requirements of plant growth.Different CO_(2)inlet has a great influence on CO_(2)concentration in greenhouse,and scheme of placing points on both sides and in the middle at the same time could get a uniformity requirement of CO_(2)concentration in greenhouse.Results also showed that directly using from industrial flue gas to carbon-rich agriculture was feasible,but in practical application process,CO_(2)concentration in flue gas,absorption rate,CO_(2)injection location,dilution ratio and pollutant concentration must be comprehensively evaluated before applied to agricultural production.