_________________________________ GIIGNL _________________________________ LNG CUSTODY TRANSFER HANDBOOK THIRD EDITION © GIIGNL 2010 GIIGNL – LNG CUSTODY TRANSFER HANDBOOK Third edition DOCUMENT STATUS AND PURPOSE This third (2010) edition of the GIIGNL LNG Custody Transfer Handbook reflects GIIGNL’s understanding of best current practice at the time of publication. The purpose of this handbook is to serve as a reference manual to assist readers to understand the procedures and equipment available to and used by the members of GIIGNL* to determine the energy quantity of LNG transferred between LNG ships and LNG terminals. It is neither a standard nor a specification. This handbook is not intended to provide the reader with a detailed LNG ship-shore custody transfer procedure as such, but sets out the practical issues and requirements to guide and facilitate a skilled operator team to work out a suitable procedure for a specific LNG ship-shore custody transfer application. Although this LNG Custody Transfer Handbook may contain much useful information, it is not specifically intended to work out procedures for ship-to-ship LNG transfer, custody transfer for LNG carriers with type C cargo tanks (IGC Code) or overland LNG custody transfer operations involving LNG trucks or trains. No proprietary procedure, nor particular manufacture of equipment, is recommended or implied suitable for any specific purpose in this handbook. Readers should ensure that they are in possession of the latest information, standards and specifications for any procedures and equipment they intend to employ. GIIGNL, and any of its members, disclaims any direct or indirect liability as to information contained in this document for any industrial, commercial or other use whatsoever. * GIIGNL Groupe International des Importateurs de Gaz Naturel Liquéfié – Paris (International Group of Liquefied Natural Gas Importers – Paris, France) GIIGNL – LNG CUSTODY TRANSFER HANDBOOK Third edition CONTENTS 1. INTRODUCTION 5 3.2.3.1 Reading of the level with float gauges 19 2. GENERAL DESCRIPTION OF THE MEASUREMENT 6 3.2.3.2 Reading of the level with capacitance and radar gauges 20 2.1. GENERAL FORMULA FOR CALCULATING THE LNG ENERGY TRANSFERRED 6 3.2.4. Correction of readings 20 2.2. GENERAL SCHEME OF THE 3.2.4.1 Float gauge 20 MEASUREMENT OPERATIONS 7 3.2.4.2 Capacitance and radar gauges 20 2.2.1. LNG Volume 7 3.2.5. Use of spare level gauge 24 2.2.2. LNG Density 8 3.2.6. Complete unloading (tank stripping) 24 2.2.3. LNG Gross calorific value 8 3.2.7. Automated systems 24 2.2.4. Energy of the gas displaced by the 3.3. CALCULATION OF THE VOLUME OF LNG transfer of LNG 8 TRANSFERRED 25 2.2.5. Flowchart for determining the energy 3.4. UNCERTAINTY OF THE VOLUME transferred 9 CALCULATION 31 2.3. INSTRUMENTS USED 9 3.4.1. Cargo Liquid Lines 31 2.3.1. For the determination of the LNG volume 9 4. TEMPERATURE MEASUREMENT 31 2.3.2. For the determination of LNG density and 4.1. LIQUID TEMPERATURE 31 gross calorific value 9 4.1.1. Device 31 2.3.3. For the determination of the energy of displaced gas 10 4.1.2. Testing and accuracy 32 2.3.4. For the determination of the energy of 4.2. VAPOUR TEMPERATURE 32 “Gas to engine room” 10 5. VAPOUR PRESSURE MEASUREMENT 32 2.3.5. Periodic instruments recalibration 10 6. SAMPLING OF GASIFIED LNG 34 2.4. STANDARDIZATION 10 6.1. LNG QUALITY 34 2.5. PARTIAL LOADING OR UNLOADING OF LNG CARRIERS 10 6.2. SAMPLING PRINCIPLES 34 3. VOLUME MEASUREMENT 11 6.3. SAMPLING POINT 35 3.1. GAUGE TABLES 11 6.4. SAMPLING PROBES 35 3.1.1. Use of gauge tables 11 6.5. PIPING ARRANGEMENT BETWEEN SAMPLING PROBE AND VAPORIZER 38 3.1.2. Correction tables 11 6.6. LNG VAPORIZER AND CONTROL 3.1.2.1 Correction according to the DEVICES 38 condition of the LNG carrier 11 6.6.1. Main devices 38 3.1.2.2 Corrections according to the temperatures in the liquid and 6.6.1.1 Water or steam vaporizer 38 gaseous phases 11 6.6.1.2 Electric vaporizer 38 3.1.3. Approval by authorities 12 6.6.2. Auxiliary vaporization control devices 41 3.1.4. Uncertainty of the gauge tables 12 6.6.2.1 On regasified LNG outlet 41 3.2. INSTRUMENTS AND METHODS FOR 6.6.2.2 On LNG inlet 41 MEASURING THE LEVEL OF LIQUID IN THE LNG CARRIER'S TANKS 18 6.6.2.3 On heating fluid (water, steam or electricity) 41 3.2.1. Main liquid level gauging devices 18 6.6.2.4 Safety devices 41 3.2.1.1 Electrical capacitance type level gauge 18 6.6.3. Operating parameters 41 3.2.1.2 Float type level gauge 18 6.6.4. Gas sample collection systems 41 3.2.1.3 Radar (microwave) type level gauge 18 6.7. GAS SAMPLE CONDITIONING 42 3.2.1.4 Laser type level gauge 19 6.7.1. Gas sample bottles 42 3.2.2. Timing of the level measurement 19 6.7.2. Direct piping to gas analyzer 42 3.2.3. Readings 19 1 GIIGNL – LNG CUSTODY TRANSFER HANDBOOK Third edition 6.8. EXAMPLES OF GENERAL ARRANGEMENT 9.3.1. Limits of the method 58 OF SAMPLING DEVICES 42 9.3.2. Formula 58 6.9. PERFORMANCE OF THE DEVICES 49 9.3.3. Charts available for calculation 58 6.10. SAMPLING PROCEDURE 49 9.3.4. Example of LNG density calculation 60 6.10.1. Sampling period 49 9.3.5. Rounding off 60 6.10.2. Sampling frequency 49 10. GROSS CALORIFIC VALUE 60 6.10.3. Purging 49 10.1. GENERAL 60 6.10.4. Sampling parameters 50 10.2. METHOD OF DETERMINATION OF THE 6.10.5. Utilisation of gas sample bottles 50 GROSS CALORIFIC VALUE 61 6.11. SPOT SAMPLING DEVICE 50 10.2.1. Determination with the help of calorimeters 61 7. GAS ANALYSIS 50 10.2.2. Determination of GCV by calculation 61 7.1. TYPE OF GAS CHROMATOGRAPH 50 10.2.2.1 Examples of formula 61 7.1.1. General arrangement 50 10.2.2.2 examples of charts of basic 7.1.2. Columns 51 physical constants 62 7.1.3. Detectors 51 10.2.2.3 example of calculation 62 7.1.4. Carrier gas 53 11. ANALYSIS REPORT 63 7.1.5. Quality of the separation of components 53 11.1. IDENTIFICATION 63 7.2. INTEGRATOR AND DATA PROCESSING 53 11.2. BASIC DATA 63 7.2.1. Integrator system 53 11.3. RESULTS 63 7.2.2. Data processing 54 12. ENERGY OF GAS DISPLACED OR 7.3. CALIBRATION 54 CONSUMED 63 7.3.1. Calibration procedure 54 12.1. ENERGY OF GAS DISPLACED FROM THE LNG TANKS 63 7.3.2. Calibration gas/working standard 54 12.2. ENERGY OF GAS CONSUMED AS FUEL 7.4. QUANTITATIVE ANALYSIS 55 BY THE LNG CARRIER 64 7.4.1. Response factors 55 13. ENERGY TRANSFER DETERMINATION 64 7.5. ENVIRONMENT FOR A GAS 14. ENERGY TRANSFER MEASUREMENT 64 CHROMATOGRAPHIC SYSTEM 55 15. OVERALL UNCERTAINTY OF THE ENERGY 7.6. ANALYSIS OF REGASIFIED LNG AND TRANSFER DETERMINATION 64 RETAINED SAMPLES 55 15.1. VOLUME 64 7.7. UNCERTAINTY OF GAS ANALYSIS 56 15.2. DENSITY 65 7.8. IMPURITIES 56 15.3. GROSS CALORIFIC VALUE 65 7.8.1. Carbon dioxide 56 15.4. GAS DISPLACED 65 7.8.2. Sulphur 56 15.5. COMBINED STANDARD UNCERTAINTY 7.8.2.1 Total sulphur 56 AND EXPANDED UNCERTAINTY OF THE 7.8.2.2 Sulphur components 56 ENERGY TRANSFER DETERMINATION 65 7.8.3. Mercury 56 16. LNG SALES CONTRACT CUSTODY TRANSFER CHECKLIST 65 8. DATA PROCESSING & TREATMENT 57 8.1. GENERAL 57 ENCLOSURE 1: CONVERSION FACTOR TABLE 8.2. DATA HANDLING: QUALITY 57 FOR ENERGY UNITS 68 8.2.1. Data processing 57 ENCLOSURE 2: LNG AND NATURAL GAS 8.2.2. Data treatment 57 CUSTODY TRANSFER METHODS 69 9. DENSITY 57 ENCLOSURE 3: OTHER RELEVANT STANDARDS 9.1. GENERAL 57 AND REFERENCES 72 9.2. DENSITY CALCULATION METHODS 58 9.3. REVISED KLOSEK-Mc KINLEY METHOD 58 ENCLOSURE 4: NOTES ON TERMINOLOGY 73 2 GIIGNL – LNG CUSTODY TRANSFER HANDBOOK Third edition LIST OF FIGURES 74 LIST OF TABLES 75 REFERENCES 76 APPENDICES 1-9 77-98 3 GIIGNL – LNG CUSTODY TRANSFER HANDBOOK Third edition 1. INTRODUCTION Following the publication in 1985 by the N.B.S. of its study Advantica Technologies Ltd. (UK) "LNG Measurement - A User's Manual for Custody BG International (UK) Transfer" [8], the Executive Committee of the GIIGNL CMS Energy Trunkline LNG Company (USA) (Groupe International des Importateurs de Gaz Naturel Distrigas (B) Liquéfié) considered it would be useful to write a Enagas (E) handbook, as simple and as practical as possible, aimed Gaz de France (F) at organizations involved in the measurement of the Nigeria LNG (NI) energy transferred in the form of LNG in the context of a NKKK (JP) LNG purchase and sales agreement, whether this sale be Osaka Gas (JP) F.O.B. [Port of loading], D.E.S. or C.I.F. [Port of Rete Gas Italia (I) unloading]. SIGTTO (UK) Tokyo Gas (JP) During its session of October 1987, the General Assembly Tractebel LNG North America (USA) of GIIGNL decided that this practical handbook should be drawn up by a Study Group comprising companies of the GIIGNL and coordinated by Distrigas S.A (B). THIRD EDITION, MARCH 2010 The methods described in this handbook could serve to Since the second edition, several new international improve existing procedures.