本文選題：揮發(fā)性有機(jī)物 + 流量控制��； 參考：《湖南師范大學(xué)》2015年碩士論文

【摘要】：揮發(fā)性有機(jī)物(VOCs)是一類常見的有機(jī)污染物,廣泛存在于大氣與水環(huán)境中。氣相色譜作為一種分離混合物各組分的高效方法,在有機(jī)污染物檢測領(lǐng)域得到了廣泛的應(yīng)用。氣相色譜的流量控制技術(shù)是實(shí)現(xiàn)水環(huán)境中揮發(fā)性有機(jī)物自動化監(jiān)測設(shè)備小型化的關(guān)鍵技術(shù)之一。目前,氣相色譜-質(zhì)譜聯(lián)用法是我國有機(jī)物檢測的主要手段,水環(huán)境中的揮發(fā)性有機(jī)物監(jiān)測對實(shí)驗(yàn)室檢測依賴比較嚴(yán)重,因此,能夠現(xiàn)場監(jiān)測揮發(fā)性有機(jī)物的自動化監(jiān)測設(shè)備亟需得到研究和開發(fā)。論文在流體力學(xué)的基礎(chǔ)上對管路內(nèi)以及色譜柱中的氣流流量的測量原理和方法進(jìn)行了分析,推導(dǎo)了氣相色譜中的流量計算公式,對模擬輸出和數(shù)字輸出的差壓傳感器性能進(jìn)行測試,為選型提供了理論指導(dǎo)。基于TM4C1233H6PM微處理器和節(jié)流差壓法設(shè)計制作了具有過流、過壓、防反接以及防雷保護(hù)的流量控制硬件,編寫了流量控制器的測控軟件。結(jié)合傳感器和被控對象以及控制器件比例閥特性,研究了基于改進(jìn)型PID控制的流量控制策略,并確定了參數(shù)整定的步驟和方法。流量控制器采用RS-485總線通信,使用ModBus通信協(xié)議作為控制器與儀器控制單元的通信協(xié)議。該氣體流量控制器能在0-600mL/min范圍內(nèi)對氣流具有較好的控制效果,其控制響應(yīng)時間小于2s,過沖小于0.5%,在控制精度上小流量時優(yōu)于0.7%,中高流量時優(yōu)于0.5%;在針對控制器通信功能干擾測試中,能夠排除錯誤幀的干擾,提取并應(yīng)答正確的數(shù)據(jù)幀。
[Abstract]:Volatile organic compounds (VOCs) are a kind of common organic pollutants, which widely exist in the atmosphere and water environment. Gas chromatography, as an efficient method for separating components of mixtures, has been widely used in the field of detection of organic pollutants. The flow control technology of gas chromatography is one of the key technologies to realize the miniaturization of volatile organic compounds (VOCs) automatic monitoring equipment in water environment. At present, gas chromatography-mass spectrometry (GC-MS) is the main method for the detection of organic compounds in China. The monitoring of volatile organic compounds in water environment depends heavily on laboratory detection. The automatic monitoring equipment which can monitor volatile organic compounds on site needs to be researched and developed. On the basis of hydrodynamics, the measuring principle and method of flow rate in pipeline and chromatographic column are analyzed, and the calculation formula of flow rate in gas chromatography is deduced. The performance of differential pressure sensor with analog output and digital output is tested, which provides theoretical guidance for selection. Based on TM4C1233H6PM microprocessor and throttle differential pressure method, the flow control hardware with overcurrent, overvoltage, anti-backconnect and lightning protection is designed and manufactured. The measurement and control software of flow controller is programmed. Based on the characteristics of sensor, controlled object and proportional valve of controller, the flow control strategy based on improved PID control is studied, and the steps and methods of parameter setting are determined. The flow controller uses RS-485 bus to communicate, and ModBus protocol is used as the communication protocol between the controller and the instrument control unit. The gas flow controller can control the airflow in the range of 0-600mL/min. The control response time is less than 2 s, the overshoot is less than 0.5, the control precision is better than 0.7 when the flow is small, and the middle and high flow is better than 0.5. In the test of interference of the communication function of the controller, the interference of error frame can be eliminated, and the correct data frame can be extracted and answered.
【學(xué)位授予單位】：湖南師范大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：X853

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本文編號：1843703