天然氣電廠交易用超音波流量計校正特性之探討

Advanced Research on the Characteristics of Ultrasonic Flowmeter Calibration for Natural Gas Power Plant

羅仁聰(Jen-Tsung Luo) ； 吳志榮(Jyh-Rong Wu) ； 黃財旺(Tsai-Wang Huang) ； 林坤海(Kun-Hai Li) ； 郭景宜(Ching-Yi Kuo) ； 楊峰銳(Fong-Ruey Yang) ； 何宜霖(Yi-Lin Ho)

《石油季刊》 49卷2期 (2013/06) Pp. 79-90

摘要

近年來環保議題為人們所重視，加以配合政府能源多源化政策，天然氣由於屬較低污染且高優質能源燃料，近年來隨著輸儲技術的進步，天然氣應用越來越普及，其於燃料領域扮演角色漸重，台灣2011年使用的天然氣約160億立方公尺，其中近8成用於電廠發電燃料用，天然氣已逐漸取代傳統燃媒及核能電廠發電，成為發電燃料主軸，台灣中油公司作為國內獨家天然氣供應商，對天然氣計量交易之公平性有不可推卸之責任，目前供應各電廠之計價用流量計已由流孔板改為大口徑多聲道超音波流量計（Multi Path Ultrasonic Flowmeter），而流量計定期校驗以維護交易公平性已成為一相當重要主題。中油各配氣站計量用超音波流量計於2009年採購時，已先於德國Pigsar流量校正實驗室進行校正，自2011年起，天然氣事業部針對大潭電廠配氣站及全省8個配氣站之超音波流量計及眾多壓力計、溫度計進行校正，委託工業技術研究院量測中心（Measure Center of ITRI）擔任第三公正角色，進行壓力計、溫度計校正及設定流量計參數調整事宜，而由中油煉製研究所氣體大流量校正實驗室（GFCL）負責流量計校正事宜。氣體大流量校正實驗室經TAF認證之ISO/IEC 17025校正能力為壓力：10～60 Bar；流率：100～4,000 m^3/hr，使用之標準件為Elster-Instromet出廠之4台6吋四聲道超音波流量計採並聯方式，可校正2至12吋流量計，每一台標準件皆於下游配有一台渦輪流量計進行現場查核，由一年來之查核結果可發現各標準件皆處在一穩定且可靠狀能，其量測不確定度為0.28 %。本文針對17部10吋及12吋超音波流量計進校正結果進行研究，並研究流量計校正周期、前直管效應，由各配氣之流量計校正結果來看，其平均器差約0.3 %，此值符合一般文獻指出之多聲道超音波流量計之器差為0.5 %以內，以供應各電廠2,000億台幣天然氣交易金額來估其交易公平性逆差約為6億元，天然氣計量用流量計定期校正以符合公平交易性之重要性不言可喻。

關鍵字

超音波 ； 校正 ； 不確定度

並列摘要

The issue of environment protection is concerned by public. In order to obey multi energy source policy of government, clean and high efficiency fuel is concerned as Nature Gas (NG). Due to the improvement of transportation and storage of NG, NG becomes a public energy fuel. In Taiwan, the use of NG in 2011 is about 16 billion cubic meters, and 80% is used as eclectic power generation fuel and replacing tradition coil fuel and nuclear power. CPC Corporation, Taiwan (CPC) as the monopoly supplier of NG, to improve the quality and technology of NG measurement is its responsibility. Since the NG measurement flowmeter for power generation has changed from traditional orifice flowmeter to multi path ultrasonic flowmeter (USM), the regular calibration of USM became an important issue. The gas feed station of CPC purchased USM from 2009, and asked to calibrate in German Pigsar flow calibration laboratory. Since 2011, CPC ask measurement Center of Industrial Technology Research Institute (ITRI) and Gas flow calibration laboratory (GFCL) to calibrate 17 USM flowmeters, temperature and pressure meters. The capacity of GFCL is 10-60 bars (pressure) and 100-4,000 m^3/hr (flow rate) which was certified by the Taiwan Accreditation Foundation (TAF). The calibration meter size is from 2 to 12 inchs in diameter. The standard meter is USM supplied from Elster-Instromet company. Each standard meters is tracked quality by a turbine meter. From the calibration results, the average error of 17 USMs is 0.3%, and this value is below announced 0.5% from reference. The NG volume trade for power generation is about 200 billion NTD and error adjust donated 0.6 billion. To calibrate flowmeter is very important to create an equitable environment for NG measurement.

並列關鍵字

Ultrasonic ； Calibration ； Uncertainty