基于激光吸收光谱的主要人为氨排放源在线检测技术与应用研究

发布时间：2018-08-15 15:25

【摘要】：氨气对环境大气、土壤、水体中的氮循环起关键作用,研究农业面源、工业点源、机动车移动源这几类排放权重高、有规律的人为氨排放源的在线检测方法并掌握其排放规律,对研究全球氮循环和环境保护具有重要意义。论文针对氨排放在线检测的技术需求,研究了氨气高温特征光谱检测方法及浓度精确反演算法,并开展区域型氨排放通量在线检测技术和应用研究。研究了氨气在近红外波段的振转吸收谱带和氨的配分函数,分析了6528.8cm-1附近的吸收光谱特性;建立了高温氨气近红外波段激光吸收光谱测量实验平台,开展了高温氨气特征光谱及线强检测实验,获得了室温和500～700K不同温度、不同压力下氨气的特征吸收光谱,并分析得到了常温及高温环境的线型和线强参数。研究了基于高分辨近红外吸收光谱高温氨气浓度反演算法,建立了基于特征光谱解析、多线Voigt线型拟合、温度参数修正的高温氨气浓度反演算法模型和实际测量环境下的光谱相关性分析算法,对多吸收线交叠的线型拟合残差优于±2%,当测量光谱与标准光谱的相关系数优于85%时检测相对误差5%,高温氨浓度反演的精度约4%。研发了高温氨气在线检测系统控制和浓度反演软件,开展了高温氨逃逸现场在线检测实验,测量结果表明:脱硝催化还原反应氨逃逸与NOx浓度呈现负相关特征。采用高温伴热尾气取样系统开展了机动车尾气氨气排放在线检测实验,怠速约为800r/min时,氨排放平均浓度约1.64ppm,转速提高到1500r/min时,氨排放平均浓度约为2.24ppm,结果表明:随着转速升高,氨气排放的浓度呈现上升趋势。研究了 OP-TDLAS技术结合bLS模型进行通量监测的有效性和数据融合方法,包括细化仪器架设光程、高度、数据平均周期等实验条件;优化区域型开放式监测方式并进行一致性分析。通过开展农田、养殖场氨排放监测应用研究,获得安徽皖北地区秸秆还田和农田施肥共同作用下的土壤氨排放规律,结果表明施肥对氨排放的增势效应更快并且持续时间更短,而秸秆还田的增势效果更明显、持续时间更长久。在黄淮海平原开展农田施肥氨排放监测,在施肥后的10天氨挥发通量较大,峰值达到5.34 kg N/(hm~2d);开展不同季节典型城市奶牛场氨排放监测,秋季氨排放速率为1.48～130.6(kg/head/hr),冬季氨排放速率约为0.0045～43.32(kg/head/hr),排放与温度、气象条件有关,体现出季节性差异。
[Abstract]:Ammonia gas plays a key role in nitrogen cycling in environmental atmosphere, soil and water body. This paper studies the on-line detection methods and the emission rules of agricultural non-point source, industrial point source and motor vehicle moving source, which have high weight and regular artificial ammonia emission source. It is of great significance to study the global nitrogen cycle and environmental protection. In order to meet the technical requirements of on-line detection of ammonia emissions, this paper studies the method of high temperature characteristic spectrum detection of ammonia gas and the accurate inversion algorithm of ammonia concentration, and carries out on-line detection technology and application research of regional ammonia emission flux. The vibrational absorption band of ammonia in near infrared band and the partition function of ammonia are studied, the absorption spectrum characteristics near 6528.8cm-1 are analyzed, and the experimental platform for measuring laser absorption spectrum of high temperature ammonia in near infrared band is established. The characteristic absorption spectra of ammonia at room temperature and 500K at different temperatures and pressures were obtained, and the line shape and line strength parameters of normal temperature and high temperature environment were analyzed. Based on the high resolution near infrared absorption spectrum, the inversion algorithm of ammonia concentration at high temperature is studied. Based on the characteristic spectrum analysis, the multi-line Voigt line fitting is established. The inversion algorithm model of high temperature ammonia concentration modified by temperature parameters and the spectral correlation analysis algorithm under the actual measurement environment, When the correlation coefficient between the measured spectrum and the standard spectrum is better than that of 85, the relative error is 5 and the inversion accuracy of ammonia concentration at high temperature is about 4. The software of high temperature ammonia on-line detection system control and concentration inversion was developed, and the field on-line detection experiment of high temperature ammonia escape was carried out. The results showed that ammonia escape from denitrification catalytic reduction reaction showed a negative correlation with NOx concentration. The on-line detection experiment of ammonia emission from motor vehicle tail gas was carried out by using the high temperature heat tracing tail gas sampling system. When the idle speed was about 800r/min, the average concentration of ammonia emission was about 1.64 ppm, and the average concentration of ammonia emission was about 2.24 ppm when the rotational speed increased to 1500r/min. The results showed that the average concentration of ammonia emission was about 2.24 ppm with the increase of rotational speed. The concentration of ammonia gas emission showed an increasing trend. The effectiveness and data fusion method of OP-TDLAS technology combined with bLS model for flux monitoring are studied, including thinning the experimental conditions of optical path, height and data mean period, optimizing the open monitoring mode and analyzing the consistency. Through the application research of ammonia emission monitoring in farmland and aquaculture farm, the soil ammonia emission law under the joint action of straw returning to field and farmland fertilization in northern Anhui Province was obtained. The results showed that the increasing effect of fertilization on ammonia emission was faster and the duration was shorter. The effect of straw returning to the field is more obvious, and the duration is longer. The ammonia emission monitoring of farmland fertilization was carried out in Huang-Huai-Hai Plain. The ammonia volatilization flux reached 5.34kg / (hm~2d) in 10 days after fertilization, and the ammonia emission monitoring was carried out in typical urban dairy farms in different seasons. The ammonia emission rate in autumn is 1.48 ~ 130.6 (kg/head/hr) and that in winter is about 0.0045 ~ 43.32 (kg/head/hr). The discharge rate is related to temperature and meteorological conditions, showing seasonal difference.
【学位授予单位】：中国科学技术大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：X831;O433

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