肥液氮素浓度在线检测装置研制

为实现肥液自动混合过程中氮素浓度的实时检测，设计了一个检测装置，该装置主要由硝酸根离子选择电极、电极信号调理电路、温度传感器、数据采集以及显示电路组成。在10-6～10-1 mol/L范围内配制了一系列标准浓度的NO3-溶液，对该检测装置进行了性能测试试验：1）以标准毫伏计 PHS-3CT 作为对比，测试了装置对电极响应电势的测量准确性，其相对误差最大为5.2%；2）在5～45℃范围内，分析了离子选择电极的温度变异性，结果表明电极响应电势随着待测溶液温度升高而呈线性变化，在此基础上采用最小二乘法的逐步拟合方法建立了温度参数模型，并对模型进行了验证，其测量误差最大为9.2%；3）采用固定干扰法分...

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Bibliographic Details
Published in农业工程学报 Vol. 31; no. 5; pp. 139 - 145
Main Author 李加念 李云青 杨启良 雷龙海 武振中
Format Journal Article
LanguageChinese
Published 昆明理工大学现代农业工程学院,昆明,650500 2015
Subjects
实时监测
检测装置
氮
浓度
离子选择电极
肥料
实时监测
fertilizers
ion selective electrode
nitrogen
real time control
离子选择电极
concentration
肥料
检测装置
氮
浓度
detection device
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ISSN1002-6819
DOI10.3969/j.issn.1002-6819.2015.05.020

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Summary:为实现肥液自动混合过程中氮素浓度的实时检测，设计了一个检测装置，该装置主要由硝酸根离子选择电极、电极信号调理电路、温度传感器、数据采集以及显示电路组成。在10-6～10-1 mol/L范围内配制了一系列标准浓度的NO3-溶液，对该检测装置进行了性能测试试验：1）以标准毫伏计 PHS-3CT 作为对比，测试了装置对电极响应电势的测量准确性，其相对误差最大为5.2%；2）在5～45℃范围内，分析了离子选择电极的温度变异性，结果表明电极响应电势随着待测溶液温度升高而呈线性变化，在此基础上采用最小二乘法的逐步拟合方法建立了温度参数模型，并对模型进行了验证，其测量误差最大为9.2%；3）采用固定干扰法分析了Cl-、SO42-、H2PO4-和HPO42-等4种干扰离子对装置测量结果的影响，结果表明Cl-引起的干扰最大，电极对Cl-的敏感性是NO3-的0.2%，因而肥液中少量的干扰离子对测量结果的影响不大。因此，该装置可满足工程上自动混肥过程中氮素浓度检测的应用要求。
Bibliography:11-2047/S
Li Jianian, Li Yunqing, Yang Qiliang, Lei Longhai, Wu Zhenzhong （Faculty of Modern Agricultural Engineering, Kunming University of Science and Technology, Kunming 650500, China）
For the realization of real-time detection of nitrogen concentration in the process of automatic mixed liquid fertilizer, a detection device was designed, which was mainly composed of a nitrate ion selective electrode, an electrode signal conditioning circuit, a temperature sensor, and a data acquisition and display circuit. There was a one-to-one correspondence between the response potential of a nitrate ion selective electrode and nitrate ion concentration. For this reason, the detection device could obtain the level of nitrate ion concentration by detecting the electrode’s response potential, and then the nitrogen concentration of liquid fertilizer had been acquired indirectly. Measuring accuracy for the electrode’s potential was a key influence factor of the device’s performance. A 1 mV error of the electrode’s potential l
ISSN:1002-6819
DOI:10.3969/j.issn.1002-6819.2015.05.020