1、 ISO 2016 Natural gas Online gas chromatograph for upstream area Gaz naturels Chromatographe en phase gazeuse en ligne pour zone amont TECHNICAL REPORT ISO/TR 14749 Reference number ISO/TR 14749:2016(E) First edition 2016-05-15 ISO/TR 14749:2016(E)ii ISO 2016 All rights reserved COPYRIGHT PROTECTED
2、DOCUMENT ISO 2016, Published in Switzerland All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior wri
3、tten permission. Permission can be requested from either ISO at the address below or ISOs member body in the country of the requester. ISO copyright office Ch. de Blandonnet 8 CP 401 CH-1214 Vernier, Geneva, Switzerland Tel. +41 22 749 01 11 Fax +41 22 749 09 47 copyrightiso.org www.iso.org ISO/TR 1
4、4749:2016(E)Foreword iv Introduction v 1 Scope . 1 2 Principle of measurement 1 2.1 General . 1 2.2 Gas composition . 1 3 Sampling and conditioning 3 4 Online gas chromatograph selection guideline 6 5 Calibration guidelines . 7 5.1 Calibration procedure . 7 5.1.1 General 7 5.1.2 Calibration . 7 5.1.
5、3 Calibration frequency 7 5.2 Calibration gases . 8 5.3 Chromatogram verification 8 5.3.1 Response Factor (RF) . 8 5.3.2 Retention Time (RT) . 8 6 V erification pr oc edur e . 8 6.1 General . 8 6.2 Visual inspection of Sample system 9 6.3 Visual inspection of analyser 9 6.4 Carrier Gas 9 6.5 Calibra
6、tion Gas 9 6.6 GC verification . 9 7 Maintenance and Corrective maintenance .10 7.1 Preventive maintenance 10 7.2 Corrective maintenance .10 8 Alarm and diagnostic 10 9 Repeatability and Reproducibility 12 9.1 Repeatability 12 9.2 Reproducibility 12 10 Data handling during GC failure 12 11 Quality C
7、ontrol of analysis data .13 Annex A (informative) Example, comparison between duty and backup GC .14 Annex B (informative) Example, Typical chromatogram .16 Annex C (informative) Example: Analysis result .18 Bibliography .19 ISO 2016 All rights reserved iii Contents Page ISO/TR 14749:2016(E) Forewor
8、d ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technica
9、l committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of ele
10、ctrotechnical standardization. The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the different types of ISO documents should be noted. This document was
11、 drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2. www.iso.org/directives Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rig
12、hts. Details of any patent rights identified during the development of the document will be in the Introduction and/or on the ISO list of patent declarations received. www.iso.org/patents Any trade name used in this document is information given for the convenience of users and does not constitute a
13、n endorsement. For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISOs adherence to the WTO principles in the Technical Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information The committe
14、e responsible for this document is ISO/TC 193, Natural gas, Subcommittee SC 3, Upstream area.iv ISO 2016 All rights reserved ISO/TR 14749:2016(E) Introduction Online Gas Chromatograph (GC) is widely used to determine hydrocarbon components in natural gas because of its “Real time” measurement and ea
15、se of use. It has become a powerful tool for both custody transfer and upstream process gas monitoring. Especially for the custody transfer which the calorific value and others gas properties such as, relative density, compressibility factor, etc. are needed for energy determination. Therefore, accu
16、racy and reliability of the equipment are crucial. With proper maintenance and handling, GC can provide an accurate result with a minimum manpower as it analyzes and provides results continuously. With technology today, the unit can do auto-calibration, alarm setting, diagnostic, troubleshooting and
17、 configuring through Human Machine Interface (HMI). Its outputs can be linked directly with Flow computer, Distributed Control System (DCS) or any remote personal computer (PC). The Natural Gas in upstream petroleum industry is normally wet. Then this Technical Report provides recommended applicatio
18、n to handling GC focus on design, selection, operation, maintenance and verification of GC and its peripheral. The purpose is to provide the whole process to proper handling the GC until getting the accurate and reliable results. It is also included the sampling system to get the representative samp
19、le, data verification, alarm, diagnostic and troubleshooting including how to deal with the data in case of being used for custody transfer purpose. Some acceptance criteria are also identified in this paper based on our historical record and performance of the equipment. ISO 2016 All rights reserve
20、d v Natural gas Online gas chromatograph for upstream area 1 Scope This Technical Report concerns the determination of hydrocarbon components up to C7+ in natural gas in upstream petroleum industry, which describes the principle of operation of GC and provides guidelines for selection, evaluation, a
21、nd factors impacting upon its performance such as sample probe, sample conditioning, installation, operation and troubleshooting. 2 Principle of measurement 2.1 General The GC is a technique for separating and analysing compounds that can be vaporized without decomposition in a continuous and automa
22、tic manner of sample injection, separation, data integration and reporting. A precise volume of sample gas is injected into the column which contains a stationary phase (packing) that is either an active solid (adsorption partition) or an inert solid support that is coated with a liquid phase (absor
23、ption partitioning). The gas is moved through the column by means of a mobile phase (carrier gas). Selective retention of the components of the sample takes place in the column and causes each component to move through the column at a different rate. This action separates the sample into its gaseous
24、 constituents. A detector detects the elution of component from the column and produces electrical outputs proportional to the concentration of each component. Output from the detector are amplified in the electronics, then transmitted to the controller for further processing. 2.2 Gas composition Na
25、tural gas is composed primarily of methane with smaller amounts of higher hydrocarbons and of non combustible gases. Major, minor and trace components are as indicated in Tables 1, 2 and 3: Table 1 Major components Component Units Methane mole % Ethane mole % Propane mole % Butanes mole % Pentanes m
26、ole % Hexanes mole % Heptanes plus mole % Nitrogen mole % Carbon dioxide mole % TECHNICAL REPORT ISO/TR 14749:2016(E) ISO 2016 All rights reserved 1 ISO/TR 14749:2016(E) Table 2 Minor component Component Units Hydrogen mole % Oxygen mole % Carbon monoxide mole % Helium mole % Table 3 Trace component
27、 Component Units Hydrogen sulfide mg/m 3 Mercaptan sulfur mg/m 3 Dialkyl (di) sulfide mg/m 3 Carbonyl sulfide mg/m 3 Total sulfur mg/m 3 Figure 1 Online Gas Chromatograph Functional Block Diagram2 ISO 2016 All rights reserved ISO/TR 14749:2016(E) Figure 2 Online Gas Chromatograph Equipment Diagram O
28、utput from the controller is normally linked to flow computer, DCS, remote personal computer (PC) or a printer. Connection between the GC Controller and others can be accomplished via a direct serial link or Ethernet link. The GC today has features to report alarm and ignore any fault (report last g
29、ood value) and also provides good diagnostic and troubleshooting data. To verify the GC performance, repeatability check with Standard gas and baseline check are recommended. 3 Sampling and conditioning The nature of gas processing in upstream petroleum industry is relied on gas separation and gas d
30、ehydration units. There is potential of small liquid droplets in Natural Gas which are able to get into GC causing lots of problems such as incorrect data, failure of GC, etc. Sample probes and sample conditioning unit have to be properly designed and installed to address liquid carry over and conde
31、nsing issues. A well designed, installed and maintained sampling system is vital to ensure the provision of a representative sample for GC analysis. The purpose of the sample handling system is not to transfer an exact sample of the process fluid to the GC. Rather, the purpose is to transfer a repre
32、sentative sample of the fluid after it has been conditioned that is compatible with GC sample requirements. The sampling system consists of sample probes, pressure regulators and sample line. The sample probe design should take into account the possibility of resonant vibration being induced by high
33、 flow velocities in the pipeline. The probe construction can be either a straight tube probe or a regulated probe. An extraction probe should be considered for maintenance purpose without depressurizing shutdown. Referring to ISO 10715, sample probe should be located directly in the gas stream in su
34、ch a way that problems induced by aerosols and dust are eliminated. It is recommended that the probe be located a minimum of 20 pipe diameters downstream from any flow-disturbing elements such as elbows, ISO 2016 All rights reserved 3 ISO/TR 14749:2016(E) headers, valves and tees. However, due to re
35、triction in the upstream petroleum industry, a distance of at least 5 pipe diameters downstream of custody metering is accepted. The location of the probe should be on the top of a horizontal part of the pipe. The sample probe tip insertion should be located between one-third and centre of the pipel
36、ine diameter. The sampling pressure, especially in upstream petroleum industry is relatively high (more than 4,137 kPa, or 600 psi) but the GC inlet pressure is designed at very low level (less than 138 kPa, or 20 psi), then pressure reduction is relatively important to prevent the liquid into GC. T
37、wo different methods are considered: Regulated probe with pressure regulator. Heated pressure regulator. The sample should be heated before reducing the pressure and the regulated probe should be equipped with fin in order to reduce liquid droplet from Joule-Thomson effect. Sampling accessories such
38、 as aerosol and/or dust trap, coalescer filter are considered to ensure that liquid droplets are eliminated. The maintenance on the liquid eliminating system should be performed as frequently as practically possible. The sampling line should be short and have a small diameter to shorten residence ti
39、me. A bypass or fast-loop line should be considered to reduce residence time. The sampling vent should comply with hazardous area classification. Whenever ambient temperature is below the hydrocarbon dew point of the stream, heat tracing on the sample line should be used to keep the sample line temp
40、erature 10 C above the gas dew point. This is in order to avoid condensation problems and to provide a representative sample to the GC. The heat tracing should be either electric or steam, however the electrical parts should comply with hazardous area classification. NOTE Typically any stream over a
41、bout 38.73MJ/SCM, or 1 040 btu/scf, will need heat tracing and insulation. If neccessary a pressure safety relief valve can be installed downstream of the pressure reducer in order to protect the GC from pressure regulator failure. Materials being used in sampling are dependent on gas composition, i
42、n most cases stainless steel is recommended, however in some areas where high amount of H2S are present (more than 50ppm) the duplex stainless steel tubing should be considered. Seats and seals should be made of (elastic) material appropriate for the intended service.4 ISO 2016 All rights reserved I
43、SO/TR 14749:2016(E) Figure 3 Online Gas Chromatograph Sampling System Components A Sample Conditioning System (SCS) is located between the process stream and the analyser inlet. The standard configuration SCS should be as represented in Figure 4. ISO 2016 All rights reserved 5 ISO/TR 14749:2016(E) K
44、ey V-1 inlet valve (sample in) V-2 outlet valve (sample to GC) V-3 outlet valve (bypass) PRV-1 pressure reducing valve PSV-1 pressure safety valve F-1 dust filter F-2 membrane filter FI-1 flow indicator Figure 4 Online Gas Chromatograph Sample Conditioning System (typical) 4 Online gas chromatograph
45、 selection guideline The GC selection guideline is described below. Gas composition: number of gas components of interest as agreed with concerned parties. The typical available analyzers can analyse hydrocarbon up to C6+ and C7+. Analysis method: any system providing adequate peak separation and an
46、alytical performance should be accepted, typical detectors used are TCD, FID and FPD. In case the trace level (ppm order of magnitude) specific equipment may be considered. Electrical equipment should comply with hazardous area classification. Instrument system should be equipped with Temperature co
47、ntroller should be monitored and adjustable. Column with tag to indicate the column information (material, length). The column should be capable of separating each gas component completely.6 ISO 2016 All rights reserved ISO/TR 14749:2016(E) Carrier gas should be equipped with pressure switch to shut
48、 off the analyser when pressure is too low. Controller should Be equipped with HMI display. Have a diagnostic program connected to controller. Have the output signal which can be either an analog communication via serial data or ethernet data. Provide chromatograph of calibration and analysis. Keep
49、calibration and analysis result. Keep alarm and event log. Report the hourly, the daily, the weekly and the monthly average. Calculate the un-normalized mole percent. Carrier gas should be inert gas, typically helium or hydrogen. The carrier gas should be of zero grade purity (99,995 % pure), with less than 5 ppm water and less than 0,5 ppm hydrocarbons. The carrier gas should be in dual cylinders with an automatic switch to one cylinder to another when pressure in one cylinder is deemed lo
