The comparison of industrial natural gas flow meters, functioning of which is based on different metering methods usage, was made, recommendations on the optimization of choice of the meter's type in accordance with operation conditions were given

Kompan, A. I.

Vlasiuk, Y. M.

Vlasyuk, L. Y.

Електронний науковий архів Івано-Франківського національного технічного університету нафти і газу

AUTOMATION AND INFORMATION TECHNOLOGY   Reliability of instrumental recording of the natural gas   UDC 681,121 Y. M. Vlasiuk Candidate of Technical Sciences Naftogaz of Ukraine National Joint Stock Company  A.I. Kompan Regional Gas Company LLC L.Y. Vlasyuk Ukrmetrteststandard SE The comparison of industrial natural gas flow meters, functioning of which is based on different metering methods usage, was made, recommendations on the optimization of choice of the meter's type in accordance with operation conditions were given. Key words: gas flow, meters, natural gas accounting, meter inaccuracy, metrology. In the 90s’ of the last century Ukraine inherited the Soviet all-national calibration scheme for means of measuring the volumetric flow of gas according to the requirements of GOST 8.143-75. This calibration scheme made it possible to use the flow meters and gas meters with relative permissible error max ± 5%. Since January 01, 1997 Ukraine, in accordance with DSTU 3383, implemented the state calibration scheme for volume and volumetric gas flow measuring tools, which allows using the working means of measuring the volumetric gas flow with relative permissible error max ± 4 %. For natural gas, according to the requirements of the Rules of Measuring the Natural Gas During Its Transportation by the Gas Distribution Networks, Supply and Demand, approved by the order of the Ministry of Energy dd. December 27, 2005 No. 618, this figure reaches ± 3 (2.5)%.  The operation of the majority significant natural gas consumption metering units (GMU) operated in the former Soviet Union is based on the use of the method of alternating pressure drop (using the diaphragm). In the course of certification of such GMUs the procedures for obtaining the consumption unit from the reference standards is unavailable, i.e. this method is indirect and associated with subjectivity of estimates. This leads to many conflict situations evaluated with much greater amounts of money than the cost of advanced metering. In addition, the accuracy of measurement with this method is affected significantly by the diaphragm pollution [1].   Table 1 Characteristics of the natural gas consumption measuring appliances based on various measurement methods   Gas consumption measurement method  Error in The main range (%) Ability to understate the readings during operation Excessive pressure (kgf/cm2 ) Loss of pressure(kgf/cm2 )Optimal diameter (mm) Q min  /Q max DependenceFrom gas density  Advantages  Disadvantages The maximum sensitivity of Q max /Q sensitivityMethod of alternating pressure difference   0.8 - 1.5 + 1 - 100 0.3 200 - 700 1/3 (6) + simplicity underestimationimpressions small range costs 50 Using the turbine meter 0.5 - 1.0 in case of damage  1 - 100 0.3 150 - 600 1/50 - high accuracy filter (compulsory) Small consumption rang  e150 Using the rotary meter 0.5 - 1.0 in case of damage  3 - 100 0.3 32 - 100 1/250 - high accuracy filter (compulsory) 1000 Using the vortex meter 1.0 - 0 - 10 0 8 - 100 0.2 150 - 400 1/10 + insensitivity to contamination  small consumption range  15 Using the ultrasonic meter 0.5 - 1.0 - 0 - 10 0 0.2 50 - 1400 1/1501/250 - insensitivity to contamination, high accuracy - 1000 Using the averaged tube 1.0 - - 0.05 300 - 1400 1/3 (6) + simplicity low accuracy 30   Table 2 Parameter / Year 1997 2005 2011 2015 CONSUMPTION Working standards, the m thod of etransfer (meter + air / gas or? P + ρ) 0.5 ÷ 0.7 1.5 0.3 ÷ 0.7 1.0 0.3 ÷ 0.7  0.6 ÷ 1.0 0.15 ÷ 0.5 0.2 ÷ 0.5 TEMPERATURE 1 0.5 0.2 0.1 PRESSURE 1 0.5 0.1 ÷ 0.25 0.05 ÷ 0.15 CALCULATION (reduction to standard conditions) > 2 (manually) > 1 (manually, some computer) 0.05 (corrector) 0.02 (corrector) TOTAL > 5 3 1.5 0.5 ÷ 0.9   Table 3   The cost of verification (calibration) of FTA for natural gas consumption (production environment - natural gas) in Europe  Conventional diameter of consumption metering appliances, mm Number of gas of consumption metering appliances in Ukraine European price for verification (calibration) per unit, EUR thousand  Total cost of verification, EUR thousand Ukrtransgas PJSC, Ukrgazvydobuvannia PJSC, Chornomornaftogaz PJSC, Ukrnafta PJSC ≥ 700 > 50 18x1.4* 1,300 400, 500 > 100 10x1.4  * 1,400 200, 300 > 200 4x1.4* 1,100 150 > 1000 3x1.4* 4,200 TOTAL, items 1 to 4 > 1300 - 8,000 Consumers   500, 700 > 50 12x1.4* 800 300, 400 > 150 6x1.4* 1,200 200 > 1,000 3x1.4* 4,200 150 > 2,000 2.2x1.4* 8,400 100 > 2,000 2x1.4* 5,600 TOTAL, items 5 to 9 > 5,200 - 22,200 TOTAL > 6,500 - 30,200 * VAT and customs fees Due to the advanced international experience, the experts of Naftogaz of Ukraine National Joint Stock Company developed a concept of creation of the unified system of natural gas accounting, which was approved by the Cabinet of Ministers of Ukraine dated August 21, 2001 No. 1089. The main goal is the creation of systems for gas, ensuring the high reliability of measurement of the gas volume. Today the advanced foreign and domestic firms developed the modern natural gas meters, the error of which is less than 0.5% (Table 1). Their introduction in Ukraine is constrained primarily due to the lack of the required metrological support. The analysis of the former error of the natural gas metering instrument is still recorded and its expected status after implementation of the major provisions on the Concept of a Unified System for Natural Gas Metering in Ukraine is presented in Table. 2. Table 2 shows the following points. Through the introduction of modern electronic correctors a significant reduction of the natural gas appliances error is marked. The error of polynomials embedded in the currently known methods of measurements using the variable pressure drop (using the diaphragm), in the best optimal ranges of consumption, pipeline diameters and module values is 0.6-0.8%. In addition, in the course of measurement using this method in the operating conditions there is an error of the primary converter of pressure drop and error in gas density determination. The commensurate error is observed upon measurement of natural gas consumption by meters calibrated (verified) at stands existing in Ukraine, the working environment is which is air (stand error is 0.3%, the error due to a mismatch between the working environment and pressure is about 0.6%). The noticeable error reduction is possible when using the methods proven in the world's best practice, namely the introduction of modern s precision meters calibrated at the stands in conditions close to the working ones, at the working pressure and with the natural gas.  A very small measurement error of the related parameters (temperature, pressure, gas composition) under current conditions, which can frequently be neglected, becomes significant during the procedure of bringing to standard conditions and measuring the gas flow in the working conditions with an accuracy of about 0.5 %. That is, in view of the error of 1% when measuring the gas consumption, it is permissible to neglect the pressure measurement error of 0.25% or the temperature measurement error of 0.65ºC. For the expected condition these errors will become material. The modern measuring devices are able to provide significantly better performance accuracy, but the relevant metrological software, unfortunately, is still lagging behind. Based on the real needs and operation conditions of specific sites, we recommend: at all GMS (both with meters of all types and diaphragm) it is required to install the effective filters without valves between them and counter or diaphragm as a possible source of contamination); for large GMS (for example, with consumption in standard conditions above 5,000 m3 per hour) it is feasible to use two accounting complexes with various measuring techniques connected in series; GMS using the method of variable pressure drop with unstable gas composition (if the gas density change is fixed at 5 to 10 g per m3 in standard conditions), the flow density meters should be included; at the newly created and renovated GMS it is required to implement the complexes (counter with corrector) implementing the functions of adjusting the additional meter errors depending on the temperature and working environment pressure change or the Reynolds number; issue of flow meters, in which the relative error in the basic range upon manufacture completion is 0.5%, and during the operation - 1%; continue the establishment and operation of stands for calibration and long-term testing of industrial meters at "natural gas" working environment with involvement of mobile standards of the Metrology Centre in Boyarka; during issue and after repair the gas meters shall be calibrated at the stands with "natural gas" working environment under working pressure and checked at the stands with "air" working environment at atmospheric pressure and in the course of the next calibration at stands with "air" working environment at atmospheric pressure. The cost of verification (calibration) of the natural gas consumption MAs in European metrological institutions accredited to perform such works at natural gas is presented in the table 3. Conclusion Thus, according to the results of the performed analysis we can state as follows [2]: A significant error reduction of the instrument for natural gas accounting, the need for which is dictated by the sharp increase in gas prices is possible only due to simultaneous introduction of modern measuring appliances (MA) and associated metrology software;  It is possible to create a system of natural gas accounting with measurement error in the basic range less than 0.6%. The required domestic metrological software is being created already, and MAs are legalized and available;   The implementation of verification (calibration) of meters for "natural gas" operation environment shall take place in stages: •   All turbine, ultrasonic and rotary meters working at high pressure; •   All ultrasonic and rotary meters working at medium pressure. References 1.   Vlasyuk Y.M. Concept of a unified system for natural gas metering in Ukraine (optimizing the implementation of industrial meters with various methods of measurement)/Y.M. Vlasyuk, M.I. Chupryn. - P. 73-75. 2.   MP 412/03-2010. A method of checking the technical condition of the GMS using EK-B installation / V.I. Kartasheva, N.V. Babichenko, V.S. Bondarenko, Y.M. Vlasyuk [et al.]. - 21 p.     Article Authors  Vlasyuk Yaroslav Mykhaylovych  Candidate of Technical Sciences, an expert in the field of automation of production processes, accounting of natural gas and metrology. He graduated from IFING. The main directions of his scientific studies is creation of electronic fiscal means of instrumental accounting, improvement of metrological software for natural gas metering appliances, calibration (verification) of industrial meters by working pressure; checking the technical condition (metrological characteristics) of the natural gas metering units in operating environment; implementation of consumption metering complexes with regulated total measurement error, self- diagnostics of the natural gas metering units.     Compan Artem Igorovych  He graduated from Kondratyuk National Technical University of Poltava with the major in Equipment for Oil and Gas Industry. His research interests are related to accounting and reasonable use of natural gas energy and savings in the industry.          Vlasyk Lilya Yaroslavivna 2nd category engineer of Ukrmetrteststandard SE. She graduated from KPI with the major in metro logy and measuring equipment, as well as linguistics. The main line of her work is verification of the nautral gas consumption measuring appliances.          

Reliability of instrumental recording of the natural gas

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Електронний науковий архів Івано-Франківського національного технічного університету нафти і газу