差壓裝置流量測(cè)量范圍度擴(kuò)展方法研究與實(shí)驗(yàn)
發(fā)布時(shí)間：2018-10-08 17:22
【摘要】：流量是過程檢測(cè)涉及的主要參數(shù)之一,其測(cè)量值的準(zhǔn)確性、有效性與設(shè)備的安全性和運(yùn)行的經(jīng)濟(jì)性直接相關(guān)。熱力發(fā)電廠生產(chǎn)過程中管內(nèi)工質(zhì)大多屬于高溫高壓流體,目前對(duì)這類流體流量在用的測(cè)量方法是差壓式流量測(cè)量裝置,而此類裝置的局限性在于其范圍度為3：1最多4：1,這就意味著在生產(chǎn)過程中,如果管流流量低于測(cè)量上限的1/或1/流量以0計(jì)。正是這種局限性導(dǎo)致熱電廠與用戶之間產(chǎn)生計(jì)量爭(zhēng)議,而作為國(guó)家標(biāo)準(zhǔn)規(guī)定的流量測(cè)量方法,差壓式流量測(cè)量裝置具有法定地位,技術(shù)監(jiān)督部門也無其他依據(jù)對(duì)上述爭(zhēng)議進(jìn)行仲裁。因此,尋求一種既嚴(yán)格遵守國(guó)家標(biāo)準(zhǔn)GB/T 2624.1～4—2006“用差壓裝置測(cè)量圓形截面管道中的滿管流體流量”的規(guī)定,又具有較大范圍度的流量測(cè)量解決方案不但具有工程實(shí)用價(jià)值,更兼有理論意義。本文從分析造成小流量工況下測(cè)量誤差大的原因出發(fā),揭示差壓式流量測(cè)量裝置范圍度小的的實(shí)質(zhì)在于差壓變送器的允許誤差在小流量時(shí)形成的相對(duì)誤差過大所致。解決問題的合理設(shè)想之一是：在小流量時(shí)使一次裝置輸出的差壓對(duì)應(yīng)的變送器輸出亦為較大值,然而實(shí)際的情況是無論一次裝置輸出差壓為何值,變送器輸出電流都將差壓成比例地轉(zhuǎn)換成4-20mADC電流,除非將輸出差壓分成多段分別測(cè)量,即將一次裝置輸出差壓由多個(gè)差壓變送器按段分別轉(zhuǎn)換成4—20mA電流。由此隨之而來的是流出系數(shù)C必須按段分別計(jì)算,工控機(jī)信號(hào)處理系統(tǒng)根據(jù)不同差壓段選擇不同流出系數(shù)。遵循著這一設(shè)想,對(duì)于差壓流量測(cè)量裝置設(shè)計(jì)命題,本論文提出的解決方案如下：第一步,按GB/ 2624.1-4—2006“用差壓裝置測(cè)量圓形截面管道中的滿管流體流量”附錄A(資料性附錄)給出的第二類命題計(jì)算方法對(duì)流量測(cè)量裝置進(jìn)行設(shè)計(jì),設(shè)計(jì)結(jié)果包含最大流量qmmax對(duì)應(yīng)一次裝置輸出差壓ΔPmax、常用流量qmch對(duì)應(yīng)一次裝置的輸出差壓ΔPch、最小流量qmmin對(duì)應(yīng)一次裝置的輸出差壓ΔPmin、流出系數(shù)C、一次裝置的開孔直徑比β；第二步,采用兩臺(tái)差壓變送器同時(shí)對(duì)一次裝置的輸出差壓進(jìn)行測(cè)量,其中差壓變送器DP1的量程為0-ΔPmax,差壓變送器DP2的量程為0～APmin,流量信號(hào)處理系統(tǒng)根據(jù)差壓值選擇其中之一進(jìn)行處理；ΔPmin-△Pmax之間的差壓由差壓變送器DP1成比例地轉(zhuǎn)換成4-20mADC電流信號(hào),0-APmin之間的差壓由差壓變送器DP2成比例地轉(zhuǎn)換成4-20mADC電流。一次裝置輸出0～ΔPmin之間的差壓時(shí)所對(duì)應(yīng)的流出系數(shù)cmin由第一類命題求解方法得到。于是該解決方案在完全遵循GB/T 2624.1-4—2006的前提下,裝置的范圍度由3：1到4：1提高到9：1到16：1。本論文設(shè)計(jì)了基于上述技術(shù)路線的實(shí)驗(yàn)方案,建造了實(shí)驗(yàn)裝置,以實(shí)驗(yàn)證明了解決方案原理的正確性和可行性。
[Abstract]:Flow rate is one of the main parameters involved in process detection. The accuracy and effectiveness of the measurement value are directly related to the safety of the equipment and the economy of operation. Most of the working fluids in the pipe are high temperature and high pressure fluids in the production process of thermal power plant. At present, the method of measuring the flow rate of this kind of fluid is the differential pressure type flow measuring device. The limitation of this type of device is that its range is up to 4: 1 at 3:1, which means that in the production process, if the flow rate of the pipe is less than 1 / 1 / 1 / 1 of the upper limit of the measurement, the flow rate is zero. It is this limitation that leads to a dispute over measurement between the thermal power plant and the user. As a national standard flow measurement method, the differential pressure flow measuring device has the legal status. The technical supervision department also does not have other basis to carry on the arbitration to the above dispute. Therefore, it is not only of engineering practical value to seek a solution that not only strictly complies with the national standard GB/T 2624.1 / 4-2006 "using differential pressure device to measure the flow rate of the full pipe in a circular section pipe", but also has a large range of flow measurement solutions. It also has theoretical significance. Based on the analysis of the causes of large measurement errors under small flow conditions, this paper reveals that the essence of the small range of differential pressure flow measuring devices lies in the relative error caused by the allowable errors of differential pressure transmitters when the flow rate is small. One of the reasonable ideas to solve the problem is that the output of the transmitter corresponding to the differential pressure output of the primary unit is also larger when the flow rate is small, but the actual situation is that no matter what the value of the differential pressure output of the primary device is, The output current of the transmitter is converted proportionally to the 4-20mADC current, unless the output differential voltage is divided into multiple sections and measured separately, that is, the output differential voltage of the primary unit is converted from multiple differential pressure transmitters to the 4-20mA current by segment. Therefore, the outflow coefficient C must be calculated according to the section, and the signal processing system of the industrial control computer chooses different outflow coefficient according to the different differential pressure section. Following this assumption, for the design proposition of differential pressure flow measurement device, the solution proposed in this paper is as follows: the first step, According to the second type propositional calculation method given in Appendix A (Information Appendix) of GB/ 2624.1-4-2006, "measuring the flow rate of full pipe in circular section pipe with differential pressure device", the design of flow measuring device is carried out. The design results include that the maximum flow rate qmmax corresponds to the primary unit output differential pressure 螖 Pmax, qmch corresponding to the primary unit output differential pressure 螖 Pch, minimum flow rate qmmin corresponding to the output differential pressure 螖 Pmin, outflow coefficient C of the primary unit, the opening diameter ratio of the primary unit to 尾; the second step, Two differential pressure transmitters are used to measure the output differential pressure of the primary device simultaneously. The differential pressure transmitter DP1 has a measuring range of 0- 螖 Pmax, differential pressure transmitter DP2, and the flow signal processing system selects one of them according to the differential pressure value to process. The differential pressure between 螖 Pmin- Pmax is converted proportionally from differential pressure transmitter (DP1) to 4-20mADC current signal (0-APmin) from differential pressure transmitter (DP2) to 4-20mADC current. The outflow coefficient cmin corresponding to the differential pressure between 0 ~ 螖 Pmin is obtained from the first class propositional solution method. Under the premise of GB/T 2624.1-4-2006, the range of the device was raised from 3:1 to 4:1 to 9:1 to 16: 1. In this paper, the experimental scheme based on the above technical route is designed and the experimental device is built to prove the correctness and feasibility of the principle of the solution.
【學(xué)位授予單位】：華北電力大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TH814
本文編號(hào)：2257633
[Abstract]:Flow rate is one of the main parameters involved in process detection. The accuracy and effectiveness of the measurement value are directly related to the safety of the equipment and the economy of operation. Most of the working fluids in the pipe are high temperature and high pressure fluids in the production process of thermal power plant. At present, the method of measuring the flow rate of this kind of fluid is the differential pressure type flow measuring device. The limitation of this type of device is that its range is up to 4: 1 at 3:1, which means that in the production process, if the flow rate of the pipe is less than 1 / 1 / 1 / 1 of the upper limit of the measurement, the flow rate is zero. It is this limitation that leads to a dispute over measurement between the thermal power plant and the user. As a national standard flow measurement method, the differential pressure flow measuring device has the legal status. The technical supervision department also does not have other basis to carry on the arbitration to the above dispute. Therefore, it is not only of engineering practical value to seek a solution that not only strictly complies with the national standard GB/T 2624.1 / 4-2006 "using differential pressure device to measure the flow rate of the full pipe in a circular section pipe", but also has a large range of flow measurement solutions. It also has theoretical significance. Based on the analysis of the causes of large measurement errors under small flow conditions, this paper reveals that the essence of the small range of differential pressure flow measuring devices lies in the relative error caused by the allowable errors of differential pressure transmitters when the flow rate is small. One of the reasonable ideas to solve the problem is that the output of the transmitter corresponding to the differential pressure output of the primary unit is also larger when the flow rate is small, but the actual situation is that no matter what the value of the differential pressure output of the primary device is, The output current of the transmitter is converted proportionally to the 4-20mADC current, unless the output differential voltage is divided into multiple sections and measured separately, that is, the output differential voltage of the primary unit is converted from multiple differential pressure transmitters to the 4-20mA current by segment. Therefore, the outflow coefficient C must be calculated according to the section, and the signal processing system of the industrial control computer chooses different outflow coefficient according to the different differential pressure section. Following this assumption, for the design proposition of differential pressure flow measurement device, the solution proposed in this paper is as follows: the first step, According to the second type propositional calculation method given in Appendix A (Information Appendix) of GB/ 2624.1-4-2006, "measuring the flow rate of full pipe in circular section pipe with differential pressure device", the design of flow measuring device is carried out. The design results include that the maximum flow rate qmmax corresponds to the primary unit output differential pressure 螖 Pmax, qmch corresponding to the primary unit output differential pressure 螖 Pch, minimum flow rate qmmin corresponding to the output differential pressure 螖 Pmin, outflow coefficient C of the primary unit, the opening diameter ratio of the primary unit to 尾; the second step, Two differential pressure transmitters are used to measure the output differential pressure of the primary device simultaneously. The differential pressure transmitter DP1 has a measuring range of 0- 螖 Pmax, differential pressure transmitter DP2, and the flow signal processing system selects one of them according to the differential pressure value to process. The differential pressure between 螖 Pmin- Pmax is converted proportionally from differential pressure transmitter (DP1) to 4-20mADC current signal (0-APmin) from differential pressure transmitter (DP2) to 4-20mADC current. The outflow coefficient cmin corresponding to the differential pressure between 0 ~ 螖 Pmin is obtained from the first class propositional solution method. Under the premise of GB/T 2624.1-4-2006, the range of the device was raised from 3:1 to 4:1 to 9:1 to 16: 1. In this paper, the experimental scheme based on the above technical route is designed and the experimental device is built to prove the correctness and feasibility of the principle of the solution.
【學(xué)位授予單位】：華北電力大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TH814
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相關(guān)期刊論文 前3條
1 周人;;大量程比的流量測(cè)量方案[J];石油化工自動(dòng)化;2011年03期
2 紀(jì)亮;;國(guó)家質(zhì)檢總局對(duì)差壓式流量計(jì)的范圍進(jìn)行界定[J];中國(guó)計(jì)量;2006年09期
3 黃詠梅,張宏建,胡赤鷹,韓冬;新DFT遞推算法在渦街流量信號(hào)處理中的應(yīng)用[J];浙江大學(xué)學(xué)報(bào)(工學(xué)版);2003年01期
，本文編號(hào)：2257633
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