本文選題：C~4D + 阻抗相消��； 參考：《浙江大學》2016年碩士論文

【摘要】：流體廣泛存在于石油、化工、冶金、能源、食品、制藥等眾多工業生產過程中。電導率是流體的一項重要基本物理參數,它的測量具有重要的工業應用價值。然而,目前工業生產過程中廣泛應用的電導率測量技術是接觸式測量,存在著電極極化效應以及電化學腐蝕反應等問題,其應用受到一定限制。電容耦合式非接觸電導檢測(Capacitively Coupled Contactless Conductivity Detection,簡寫為C4D)技術是一種新型電導率測量技術,可有效克服接觸式電導率測量技術所存在的問題。然而,耦合電容的存在極大地限制了現有C4D傳感器的測量范圍、測量分辨率以及測量靈敏度。為克服耦合電容的影響,研究者們提出了諸如高頻法、電壓差法、諧振法以及PSD (Phase Sensitive Demodulation)法等方法。但這些方法還存在著實現復雜或激勵頻率不可調等不足,因此仍需尋求新的克服耦合電容影響的思路和方法。本文基于阻抗相消原理,設計了一種新型C4D傳感器,以克服傳統C4D傳感器中耦合電容的影響,并將其應用于流體電導率測量和氣液兩相流參數測量當中。本文的主要工作和創新點概括如下：(1)提出了一種基于阻抗相消的新型C4D測量方法。該方法通過構建容性阻抗,將其阻抗信號與耦合電容的阻抗信號進行差分,從而消除耦合電容的不利影響。提高了C4D傳感器的測量分辨率和適用范圍,并從原理上降低了C4D傳感器對激勵頻率的要求。(2)設計研發了阻抗相消模塊,該模塊由阻抗提取模塊、容性阻抗模塊、差分模塊三個子模塊構成,可有效地消除C4D傳感器測量通路中耦合電容的影響。(3)設計了一種基于阻抗相消的新型C4D傳感器,研制了由阻抗相消模塊、傳感元件、信號處理電路以及數據采集模塊組成的硬件系統,編寫了相應的軟件程序。(4)在1.8 mm、3.3 mm、5.4 mm和7.6 mm四種內徑的管道中對新型C4D傳感器進行了電導率測量、頻率特性和輸出特性對比實驗研究。實驗結果表明：所設計的新型C4D傳感器是成功的,其電導率測量性能令人滿意,電導率測量值與商業型接觸式電導率儀的參考值相比,最大相對偏差小于5%；新型C4D傳感器的激勵頻率可在150 kHz - 400 kHz范圍內調節,整體輸出特性一致,減小了C4D傳感器對激勵頻率的依賴；新型C4D傳感器有效克服了耦合電容對測量造成的不利影響,具有較好的測量靈敏度。(5)將基于阻抗相消的新型C4D傳感器應用于氣液兩相流參數檢測,搭建了一套氣液兩相流參數測量系統。在內徑為3.3 mm和3.8 mm的管道內進行了初步的實驗研究,獲取了氣液兩相流在不同流型下的電導率測量信號,分析了不同流型下的電導率信號特征,并對典型的段塞流/泡狀流進行了氣液兩相流相關流速測量實驗。實驗結果表明：所設計的新型C4D傳感器的輸出信號能夠反映氣液兩相流不同流型下的流動特性,可應用于氣液兩相流的參數測量。總體而言,本研究提出的基于阻抗相消的新型C4D測量方法是可行的。該方法可克服C4D傳感器中耦合電容的不利影響,可有效提高C4D傳感器的測量分辨率和適用范圍,減小C4D傳感器對激勵頻率的依賴。所設計的基于阻抗相消的新型C4D傳感器是成功的。該新型C4D傳感器具有良好的測量性能,可應用于流體電導率測量和氣液兩相流參數測量。
[Abstract]:Fluid is widely used in many industrial processes, such as petroleum, chemical, metallurgical, energy, food, and pharmaceuticals. Electrical conductivity is an important basic physical parameter of the fluid. Its measurement has important industrial application value. However, the electrical conductivity measurement technology widely used in the process of industrial production is contact measurement, and there is an electrode pole. The application of chemical effect and electrochemical corrosion reaction is limited. The capacitive coupling non-contact conductivity detection (Capacitively Coupled Contactless Conductivity Detection, abbreviated C4D) technology is a new electrical conductivity measurement technology, which can effectively overcome the problems existing in the contact conductivity measurement technology. In order to overcome the influence of coupling capacitance, researchers have proposed methods such as high frequency method, voltage difference method, resonance method and PSD (Phase Sensitive Demodulation) method to overcome the influence of coupling capacitance. It is still necessary to seek new ideas and methods to overcome the influence of coupling capacitance. Based on the principle of impedance cancellation, a new type of C4D sensor is designed to overcome the influence of the coupling capacitance in the traditional C4D sensor and is applied to the measurement of the conductivity of the fluid and the measurement of the parameters of the gas-liquid two phase flow. The work and innovation points are summarized as follows: (1) a new C4D measurement method based on impedance cancellation is proposed. By constructing the capacitive impedance, the impedance signal is separated from the impedance signal of the coupled capacitance, thus eliminating the adverse effect of the coupling capacitance. The measurement resolution and the scope of application of the C4D sensor are improved and the principle is obtained from the principle. The requirements of the C4D sensor on the excitation frequency are reduced. (2) the impedance cancellation module is designed and developed. The module consists of the impedance extraction module, the capacitive impedance module and the differential module three sub modules, which can effectively eliminate the influence of the coupling capacitance in the measurement path of the C4D sensor. (3) a new type of C4D sensor based on impedance cancellation is designed. The hardware system composed of impedance cancellation module, sensing element, signal processing circuit and data acquisition module is made, and the corresponding software program is written. (4) the conductivity measurement, frequency characteristic and output characteristic comparison experiment of the new C4D sensor are carried out in the 1.8 mm, 3.3 mm, 5.4 mm and 7.6 mm internal diameter pipes. Experimental results are compared. The results show that the new C4D sensor is successful and its conductivity measurement performance is satisfactory. Compared with the reference value of commercial type contact conductivity meter, the maximum relative deviation is less than 5%. The exciting frequency of the new C4D sensor can be adjusted in the 150 kHz to 400 kHz enclosure, the overall output characteristic is consistent, and the C4D is reduced. The sensor is dependent on the excitation frequency; the new C4D sensor effectively overcomes the adverse effect of the coupling capacitance on the measurement, and has a better measurement sensitivity. (5) a new C4D sensor based on the impedance cancellation is applied to the gas liquid two phase flow parameters detection, and a set of gas liquid two phase flow parameters measurement system is set up. The internal diameter is 3.3 mm and 3.8. A preliminary experimental study was carried out in the MM pipeline. The conductivity signal of the gas-liquid two phase flow under different flow patterns was obtained. The characteristics of the conductivity signal under different flow patterns were analyzed. A typical slug / bubbly flow was measured by the measurement of the flow velocity of the gas-liquid two phase flow. The results showed that the new C4D sensor was designed. The output signal can reflect the flow characteristics of the gas-liquid two phase flow, and can be applied to the measurement of the parameters of the gas-liquid two phase flow. In general, the new C4D measurement method based on the impedance cancellation proposed in this study is feasible. This method can overcome the non profit effect of the coupling capacitance in the C4D sensor and can effectively improve the measurement of the C4D sensor. The discrimination rate and the scope of application reduce the dependence of the C4D sensor on the excitation frequency. The new type of C4D sensor based on impedance cancellation is successful. The new C4D sensor has good measurement performance and can be applied to the measurement of fluid conductivity and gas liquid two phase flow parameters.
【學位授予單位】：浙江大學
【學位級別】：碩士
【學位授予年份】：2016
【分類號】：TP212

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本文編號：2020421