本文選題：孔板流量計(jì) + 計(jì)量精度　； 參考：《西南石油大學(xué)》2014年碩士論文

【摘要】：標(biāo)準(zhǔn)孔板流量計(jì)因其結(jié)構(gòu)簡單,操作方便、技術(shù)成熟、性能穩(wěn)定且無需標(biāo)定,廣泛應(yīng)用于天然氣計(jì)量。提高標(biāo)準(zhǔn)孔板流量計(jì)的計(jì)量精度,對(duì)控制因孔板流量計(jì)自身系統(tǒng)的原因造成的城市天然氣系統(tǒng)輸差和保證天然氣交接計(jì)量公平性具有重要意義。利用FLUENT仿真軟件進(jìn)行流場模擬,通過模擬數(shù)據(jù)的定量分析,可為提高孔板流量計(jì)計(jì)量精度提供理論支撐和實(shí)際指導(dǎo)。 首先分析了管徑為DN80和DN150時(shí)流速、雷諾數(shù)、孔板自身的結(jié)構(gòu)因素(直徑比、斜角和孔板厚度)對(duì)孔板流量計(jì)流u系數(shù)的影響。通過模擬發(fā)現(xiàn)：(1)當(dāng)流速在1-15m/s范圍之內(nèi)時(shí),流出系數(shù)的相對(duì)誤差都比較小,當(dāng)流速大于15m/s時(shí),流出系數(shù)的相對(duì)誤差較大,因此,需將流速限制在15m/s以下；(2)直徑比β在0.45～0.65之間時(shí),流出系數(shù)的相對(duì)誤差較小,建議孔板流量計(jì)直徑比β盡量選擇在0.45～0.65之間,最好選擇中間值；(3)當(dāng)斜角F=45°時(shí)模擬流出系數(shù)的相對(duì)誤差最小,建議在使用孔板流量計(jì)時(shí)斜角F盡量為45°；(4)管徑為DN80的孔板流量計(jì)的孔板厚度E為1～3mm時(shí),流出系數(shù)的相對(duì)誤差較小,當(dāng)E4mm時(shí)模擬流出系數(shù)的相對(duì)誤差較大,建議管徑為DN80的孔板流量計(jì)在使用時(shí)孔板厚度E盡量小于4mm。 在對(duì)流量計(jì)自身結(jié)構(gòu)分析的基礎(chǔ)上,結(jié)合國內(nèi)外常見孔板流量計(jì)計(jì)量流程及整流裝置,進(jìn)一步分析計(jì)量系統(tǒng)對(duì)流量計(jì)計(jì)量精度的影響。討論了孔板流量計(jì)上游的擴(kuò)散管及匯管對(duì)天然氣計(jì)量段流場影響的規(guī)律,確定孔板流量計(jì)在不同情況下直管段的安裝長度。模擬結(jié)果表明：(1)在擴(kuò)散管管路中安裝19管束整流器孔板流量計(jì)前直管段長度為6倍管徑,與不安裝19管束整流器的擴(kuò)散管相比孔板流量計(jì)前直管段長度縮短了11倍管徑；(2)在進(jìn)口相對(duì)的匯管管路中安裝19管束的整流器,孔板流量計(jì)前直管段長度為8倍管徑,與進(jìn)口相對(duì)且無整流器的匯管管路相比孔板流量計(jì)前直管段長度縮短了17倍管徑；在進(jìn)口交錯(cuò)的匯管管路中安裝19管束的整流器孔板流量計(jì)前直管段長度至少為10倍管徑,與進(jìn)口交錯(cuò)且無整流器的匯管管路相比孔板流量計(jì)前直管段長度至少縮短了20倍管徑。 本文主要利用FLUENT仿真軟件對(duì)孔板流量計(jì)的計(jì)量精度進(jìn)行研究,所得到的建議可以用于提高孔板流量計(jì)計(jì)量精度,也可以用于縮短孔板流量計(jì)前直管段長度,避免因站場的布局達(dá)不到標(biāo)準(zhǔn)的要求降低孔板流量計(jì)的計(jì)量精度。從而達(dá)到嚴(yán)格控制城市天然氣系統(tǒng)因孔板流量計(jì)自身系統(tǒng)的原因造成的輸差,保證天然氣交接計(jì)量的準(zhǔn)確性和公
[Abstract]:Standard orifice Flowmeter is widely used in natural gas measurement because of its simple structure, convenient operation, mature technology, stable performance and no need of calibration. It is of great significance to improve the measurement accuracy of the standard orifice plate Flowmeter to control the transportation difference of the urban natural gas system caused by the system of the orifice plate Flowmeter and to ensure the fairness of the measurement of the natural gas transfer. Using FLUENT software to simulate the flow field, the quantitative analysis of the simulated data can provide theoretical support and practical guidance for improving the measurement accuracy of the orifice plate Flowmeter. Firstly, the influence of flow velocity, Reynolds number and orifice plate structure factors (diameter ratio, angle and thickness of orifice plate) on flow coefficient of orifice plate Flowmeter is analyzed when the diameter of the tube is DN80 and DN150. It is found by simulation that the relative error of outflow coefficient is smaller when flow velocity is within the range of 1-15m/s, and when velocity is greater than 15m/s, the relative error of outflow coefficient is larger. Therefore, when the velocity of flow is limited below 15m/s, the diameter ratio 尾 is between 0.45 and 0.65. The relative error of efflux coefficient is relatively small. It is suggested that the diameter ratio 尾 of orifice plate Flowmeter should be chosen between 0.45 and 0.65 as far as possible, and the intermediate value should be chosen as low as 3.) when the angle is 45 擄, the relative error of simulated outflow coefficient is the smallest. It is suggested that when the orifice Flowmeter is used, the relative error of the efflux coefficient is smaller when the orifice thickness E of the orifice Flowmeter with the diameter of DN80 is 1~3mm, and the relative error of the simulated efflux coefficient is larger when the E4mm is used. It is suggested that the orifice plate Flowmeter with diameter of DN80 should be less than 4 mm in thickness. Based on the analysis of the structure of the Flowmeter, the influence of the metering system on the measuring accuracy of the Flowmeter is further analyzed by combining the flow chart of orifice Flowmeter at home and abroad and the rectifying device. The influence of the upstream diffusive tube and the sink tube on the flow field of the natural gas metering section is discussed, and the installation length of the straight pipe section of the orifice plate Flowmeter under different conditions is determined. The simulation results show that the length of the straight pipe section in front of the orifice plate Flowmeter of 19 tube bundle rectifiers is 6 times the diameter of the tube installed in the diffusion pipe line. Compared with the diffusion tube without the 19 tube bundle rectifier, the length of the straight pipe section in front of the orifice Flowmeter is reduced by 11 times the diameter of the tube). The rectifier of the 19 tube bundle is installed in the inlet relative manifold line. The length of the straight pipe section before the orifice Flowmeter is 8 times the diameter of the tube. The length of the straight pipe section in front of the orifice Flowmeter is reduced by 17 times compared with the inlet tube line with no rectifier, and the length of the straight pipe section in front of the rectifier orifice Flowmeter with 19 tube bundles installed in the inlet staggered pipe line is at least 10 times the diameter of the tube. The length of the straight pipe in front of the orifice Flowmeter is at least 20 times shorter than that of the inlet staggered and no rectifier manifold. In this paper, the measurement accuracy of orifice Flowmeter is studied by using FLUENT simulation software. The suggestions can be used to improve the metering accuracy of the orifice Flowmeter and to shorten the length of the straight pipe section in front of the Hole Plate Flowmeter. Avoid reducing the metering accuracy of orifice Flowmeter because the layout of the station is not up to the standard. Thus, the transportation difference caused by the orifice Flowmeter system in urban natural gas system can be strictly controlled, and the accuracy of natural gas transfer measurement can be ensured.
【學(xué)位授予單位】：西南石油大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：TH814

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