Technical Note: Own Use Gas Model for Pre-Heaters Issue: 2.0 Advantica Stoner Professional Services (Europe) Technical Note Note MonthMay 20012002 OperatorOwn Use EyeGas TrackingModel for Pre-Heaters Confidential RestrictedRestricted to toTransco Transco & & Advantica Advantica Prepared for: Prepared by: Prepared for: Prepared by: John Wilson Clive Whitehand, Chris P Waghorn, Matthew Mullen Peter Chambers C.P.Waghorn Transco Advantica Technologies Limited Transco Advantica Technologies Limited United Kingdom Ashby Road Norgas House Ashby Road Loughborough PO Box 1GB Loughborough Leicestershire Killingworth Leicestershire LE11 3GR Newcastle upon Tyne LE11 3GR United Kingdom United Kingdom United Kingdom Tel: +44(0)1509 282218 Tel: +44(0)1509 282525 Fax: +44(0)1509 283131 Fax: +44(0)1509 283131 E-mail: [email protected] E-mail: [email protected] Website: www.advanticatech.com Website: www.advanticatech.com CustomerCustomer Reference: Reference: Filename: Final_Own_Use_Gas_Tech_Note (2.0).doc IU2.36 Future Control Room Advantica Stoner is a trading name of Advantica Technologies Ltd. Registered in England and Wales No. 3294136. Registered Office: 130 Jermyn Street, London, SW1Y 4UR, and of Stoner Associates Europe Ltd. Registered in England and Wales; No.2593248. Registered office as above. Confidential Page 1 30/09/2011 Technical Note: Own Use Gas Model for Pre-Heaters Issue: 2.0 Project Code : 1/03018 Distribution : Name Company John Wilson Transco Simon Ashmore Transco Approval : Author(s): Clive Whitehand, Chris P Waghorn, Matthew Mullen, Chris Robinson Team Clive Whitehand Leader: Project Adrian Jickells. Manager: Recipients of this page may obtain a copy of this note from: Advantica Technologies Ltd, Ashby Road, Loughborough, Leicestershire, LE11 3GR. Telephone 01509 282525 Facsimile 01509 283131 Glossary This section contains a brief description of each acronym and some commonly used terminology that are included within the document. NTS pre-Heater: The heater itself consists of a gas burner and a large water container through which pipes carrying the H.P. gas are run. LDZ pre-Heater: As above but for lower volumes and pressure gas. HPMIS: High Pressure Metering Information system. GTMS: Gas Transportation Management System. SQL: Structured Query Language – used to carry out operations on data stored in database tables. SCPN: Station Code Point Name. Advantica Stoner is a trading name of Advantica Technologies Ltd. Registered in England and Wales No. 3294136. Registered Office: 130 Jermyn Street, London, SW1Y 4UR, and of Stoner Associates Europe Ltd. Registered in England and Wales; No.2593248. Registered office as above. Confidential Page 2 30/09/2011 Technical Note: Own Use Gas Model for Pre-Heaters Issue: 2.0 Executive Summary LDZ Shrinkage is comprised of three elements: • Leakage from the low pressure asset. • Own Use Gas, the gas used for pre-heating to counter the Joule Thompson effect on pressure reduction. • Theft of gas deemed to be Transco responsibility. Shrinkage gas is procured on the basis of factors applied to throughput. For the Gas Year 2001/2002 Transco proposed a national LDZ Shrinkage Factor of 0.86%. Each 0.01% of throughput represents around £0.5million shrinkage cost. Clearly there is a driver to make accurate assessments of usage and also identify measures to reduce levels. The national factor is comprised of LDZ specific factors for Leakage and national factors for Own Use Gas and Theft of Gas. • Leakage (0.77%) • Own Use Gas (0.06%) • Theft of Gas (0.03%) This project has been funded in two £50K phases and develops a new robust model indicating a saving of £2.5M in the assessment of OUG for the year 2000. The Transco model used to assess the Own Use Gas component is a pragmatic approach, applying thermodynamic principles with a range of assumptions which includes all gas into an LDZ passes through one offtake, and is subject to a two stage pressure reduction process with a plant efficiency assumed to be 50%. Metered data where available is not used. The intention of this work was to review the current Transco model, develop an enhanced model and make an assessment of OUG consumption for the calendar year 2000. The new model is much more sophisticated in its analysis of the data. Advantica experience in both Network Modelling and Gas Quality issues have been applied to a newly created large data base with national hourly coverage for key parameters. This has led to the situation where many previous assumptions, areas overlooked and estimations have been swept away. The assessment of OUG consumption has, as with all models, an uncertainty associated with it due to the confidence levels within the data input to the model. The major sources of uncertainty are the efficiencies of the water bath heaters. The 95% confidence intervals, based on the uncertainty in the estimation of the missing data, were found to be 0.0139% and 0.0104%. On this basis the assessment of OUG consumption for the calendar year 2000 was calculated as 0.0113%. Advantica Stoner is a trading name of Advantica Technologies Ltd. Registered in England and Wales No. 3294136. Registered Office: 130 Jermyn Street, London, SW1Y 4UR, and of Stoner Associates Europe Ltd. Registered in England and Wales; No.2593248. Registered office as above. Confidential Page 3 30/09/2011 Technical Note: Own Use Gas Model for Pre-Heaters Issue: 2.0 Contents 1 Introduction .......................................................................................................................5 2 Aims of the project............................................................................................................6 3 Data Collection ..................................................................................................................7 3.1 HPMIS ..........................................................................................................................7 3.2 GTMS ...........................................................................................................................7 3.3 AT_LINK ........................................................................................................................7 3.4 PRE-HEATER SURVEY DATA............................................................................................8 3.4.1 Ground temperatures.............................................................................................8 4 Transco Model Review......................................................................................................9 4.1 PRINCIPLE......................................................................................................................9 4.2 ASSUMPTIONS................................................................................................................9 4.3 INPUT DATA ....................................................................................................................9 4.4 METHODOLOGY ..............................................................................................................9 4.5 ASSESSMENT ...............................................................................................................10 4.6 CONCLUSIONS..............................................................................................................11 5 Advantica Model..............................................................................................................12 5.1 THE METHOD ...............................................................................................................12 5.2 NEGATIVE TEMPERATURE RISE ISSUES..........................................................................13 5.3 MODEL VALIDATION.......................................................................................................13 5.4 AREAS FOR FUTURE MODEL REFINEMENT.......................................................................14 6 Database ..........................................................................................................................15 7 Accessing the Database .................................................................................................16 8 Assumptions....................................................................................................................18 8.1 PRE-HEATER EFFICIENCIES...........................................................................................18 8.2 PRE-HEATER OPERATING REGIMES...............................................................................19 8.3 NTS OFF TAKES WITHOUT GTMS DATA........................................................................19 8.4 LDZ OFF TAKES ...........................................................................................................19 9 Own Use Gas Consumption 2000 ..................................................................................20 10 Uncertanties within the New Model .............................................................................21 11 Conclusions...................................................................................................................22 12 Recommendations ........................................................................................................23 13 References.....................................................................................................................23 14 Acknowledgements.......................................................................................................23