FULL-SCALE LNG TRIALS OF A NEW TRANSFER SYSTEM ON THE GAZ DE FRANCE MONTOIR LNG TERMINAL

Transcription

1 FULL-SCALE LNG TRIALS OF A NEW TRANSFER SYSTEM ON THE GAZ DE FRANCE MONTOIR LNG TERMINAL Guillaume Rombaut Project Manager Gaz de France SA Saint-Denis La Plaine, 93211, France guillaume.rombaut@gazdefrance.com Phillip Cox Business Development Manager Technip France Paris La Défense, 92973, France Bernard Dupont Director Eurodim SA Rueil Malmaison, 92566, France Pascal Vinzio Valve Technical Director KSB SAS Gradignan, 33173, France ABSTRACT Future development of LNG projects, whether for export or import facilities, in sheltered or harsh environments (in term of marine and meteorological conditions) rely on the ability of the LNG Industry actors to bring innovative technical solutions to tackle the problem of LNG transfer in open sea. Since there is a spectrum of offshore LNG transfer solutions in development, cryogenic flexible hose based LNG transfer systems appear to answer the LNG Industry requirements in term of performances. The full-scale LNG trials to be performed at the Gaz de France Montoir-de-Bretagne LNG receiving terminal are the last stage of a complete and serious development of such solution. These industrial trials are part of a whole qualification process managed by a certification organism through a recognised procedure for the qualification of new technology. The Amplitude-LNG Loading System (ALLS) has been under development for the past six years and is now at the edge to demonstrate its performances for LNG transfer in dynamic conditions with significant wave height up to 5.5 m. PS6-4.1

2 INTRODUCTION This paper will focus on the last qualification stage of the Amplitude-LNG Loading System (ALLS) based on cryogenic flexible hose technology at the Gaz de France Montoir-de-Bretagne LNG receiving terminal. This new technology has been developed as an integrated solution for LNG transfer in ship-to-shore and ship-to-ship configurations and from sheltered to harsh environments. Indeed, the offshore installations represent a vehicle for progress consistent with the LNG market growth and it opens new perspectives and new challenges for the whole LNG Industry. In order to ensure that these new LNG chains operate correctly and at an optimum rate, the development of an efficient and safe LNG transfer system is a key link on which progress is still challenging the actors involved in this field. Whilst the transfer of LNG in real offshore conditions is a recent requirement, and several systems are under development, there is no actual system in operation, which is able to withstand the marine and meteorological conditions required by the offshore LNG chains to guarantee their availability. Based on these assessments, any LNG transfer system has to comply with the following criteria: Fundamental safety; Existing standards and specifications, as far as they can be applied in an offshore context; Project specifications and requirements; Marine classification regulations; Marine and meteorological conditions even severe; Ensure offloading from different LNG carrier sizes, without adversely affecting the carriers themselves. In addition, the transfer system must propose procedures for operational connection, disconnection, emergency disconnection, storage and replacement, with full safety and repeatability. To achieve these requirements, the development of a new LNG transfer system should be governed by close partnerships between LNG operators, engineering s and equipment manufacturers. Furthermore, certification organisms have to be involved to guarantee that the innovative solution meets the LNG industry standards. The ALLS development has followed these basic principles, the full-scale LNG trials program through a Joint Industry Project (JIP) being the last stage in order to obtain a full qualification of the system. PS6-4.2

3 AMPLITUDE-LNG LOADING SYSTEM (ALLS) The innovative LNG transfer system called Amplitude-LNG Loading System (ALLS) has been conceived and developed through a series of phased developments by a consortium of companies, consisting currently of Gaz de France, Technip France, Eurodim and KSB. All development phases, from 1999 to 2006, have been governed through JIP s involving major Oil & Gas companies, LNG operators, engineering companies and the ALLS consortium. Detailed description of ALLS functionalities and main characteristics are given in the following references [1-4]. Here below is a whole conceptual scheme of ALLS. Cryogenic flexible hose Eurodim and KSB patent pending Guiding and Alignment Device QCDC TAS ETBV ERS ERC Figure 1: ALLS (ETBV: Eccentric Tandem Butterfly Valves; ERC: Emergency Release Coupler; TAS: Tandem Actuating System; QCDC: Quick Connect Disconnect Coupler). Certification levels of the ALLS components and system itself are: QCDC, ERS, Guiding and Alignment Device (Connectis TM ): Type Approval issued by Bureau Veritas (BV); Cryogenic flexible hose: Concept Approval issued by Bureau Veritas (BV) and Type Approval to be issued during the current Montoir OPU JIP; ALLS: Statement of Endorsement issued by Det Norske Veritas (DNV) PS6-4.3

4 QUALIFICATION PROCESS Technology qualification is the process of providing the evidence that a new technology will operate reliably within specific limits by applying a structured approach to ensure a traceable and transparent qualification process. The reference document for the ALLS qualification process managed by DNV is DNV-RP-A203: Qualification Procedures for New Technology. This qualification work process ensures that all aspects of new technology are adequately addressed and the technology is proven to comply with stated functional requirements and reliability targets. The process starts off by defining the qualification basis, with functional requirements and reliability targets, which the technology is to meet. Then the system is divided into manageable parts, and classified with respect to novelty (technology assessment). Following this, a thorough risk-ranking process identifies all potential failure modes of concern. Qualification activities are thus defined to address those failure modes. The activities of the qualification plan are then assessed with respect to the likelihood of these being successfully completed within the available time. Depending on the probability of success of the project, a Statement of Endorsement can be issued. Finally the activities of the technology qualification plan are executed to derive all the information needed to reduce the uncertainties to an acceptable level in order to obtain a Statement of Fitness for Service. This methodology has been applied to ALLS and the full-scale LNG trials at the Gaz de France Montoir-de-Bretagne LNG receiving terminal are part of the whole qualification process. The main functional requirements related to the use of ALLS as LNG transfer system are: Table 1: ALLS typical functional requirements related to the qualification. LNG line LNG vapour return line Diameter 8 to 24 8 to 24 Design pressure (barg) Design temperature C C Typical flow rate 10,000 m 3 /h (with three 16 flexible hoses) 30,000 (n)m 3 /h Note: LNG and vapour return lines are technically identical and fully interchangeable if necessary. MONTOIR OPERATIONAL PILOT UNIT (OPU) The Montoir OPU JIP is sponsored by Gaz de France, BP Exploration, Chevron Energy, Conoco Shipping Company, Hoëgh LNG and Total and involved the ALLS consortium. This JIP led by Technip France involved Det Norske Veritas for the qualification process. PS6-4.4

5 LNG full-scale trials requirements The requirement to carry out full-scale dynamic testing, with circulation of LNG, was deemed necessary by the ALLS consortium as well as the group of sponsors constituted of future LNG operators. However as no offshore LNG plants exist it was decided, thanks to a proposal by Gaz de France, to study the possibility of carrying out a full-scale test program in the Gaz de France Montoir-de-Bretagne LNG receiving terminal on the West coast of France. Due to the sensitive nature of all such terminals, a complete FEED (Front End Engineering Design) and process compatibility study had to be carried out prior to any final go-ahead being given. FEED phase During the execution of this FEED the following objectives for the full-scale test program were defined: To demonstrate the viability of the ALLS through the qualification of all of the operating procedures and functionalities from sheltered to harsh environments; To check and confirm the behaviour and performances of the system on real cryogenic fluid transfer conditions; To prove that the ALLS complies with the needs and requirements of all relevant Authorities and actors involved in traditional terminals; The conclusions of the FEED were that the full-scale trials were feasible, in spite of the added difficulties of working in an operating terminal, in an ATEX (EXplosive ATmosphere) environment, and the need for local governmental approval and authorisation. In addition, DNV issued a Statement of Endorsement (certificate reference SOE 2004/001), which stated that the ALLS technology could be proven Fit for Service by successfully carrying out the remaining planned qualification activities. Qualification activities Ship-to-shore and ship-to-ship (tandem) configurations. During the FEED phase a complete qualification work process led by DNV was carried out on the ALLS, with the identification of 16 high-risk activities linked to 7 potential failure modes, which are: Shut down valves no longer operable Failure of Position Management System Inability to perform purge and drainage LNG Carrier drift / drive off LNG release (emergency disconnection) Pull-in winch fails to connect Mechanical damage to end connector. Ship-to-ship (side-by-side) configuration and control command. The qualification work process has been updated during the Montoir OPU phase leading to 6 new potential PS6-4.5

6 failure modes (3 for the side-by-side configuration and 3 for the control command) corresponding to few high-risk activities. These failure modes are: Side-by-side configuration: o Collision with outboard equipment during LNG transfer; o Flexible hose catenary in contact with sea during LNG transfer; o ESD1 failure resulting in damage of the offloading system; Control command: o QCDC open unintentionally during LNG transfer; o ERC fails to open through the PLC (Programmable Logic Controller); o ERC fails to open manually. It can be readily seen that all these failure modes, whilst needing to be fully addressed and resolved, are applicable to any LNG transfer system. HAZID study During the FEED phase a complete HAZID (Hazard Identification) workshop led by DNV was carried out on the Operational Pilot Unit (OPU means the test bench and all its equipments). This HAZID has been updated during the Montoir OPU phase. HAZOP study A full HAZOP study was conducted during the FEED phase to identify any items that could result in unsafe operating conditions or unexpected operational difficulties. The HAZOP has been also updated during the Montoir OPU phase to take into account all the functionalities of the test bench and the procedures developed. Safety study General approach. The particular safety study carried out by Gaz de France can be distinguished from a classical one because it does not concern functionality related to terminal operation and is limited to few types of equipment. Furthermore, the innovative nature of ALLS and the temporary use of the dynamic test bench required adapting the classical safety study methodology. After the systematic analysis of the hazards and the assessment of the seriousness of the scenarios, the effects caused by all of the scenarios appear to be inflated by a worstcase scenario. Furthermore, the measures adopted to prevent this scenario or to lessen its effects encompass all of the measures that must be implemented for other less serious scenarios. Dimensioning scenario. The worst-case scenario concerns an LNG test at full flow with a guillotine rupture of the flexible hose at the test bench (4000 m 3 /hr for 30s followed by a valve emergency shut down) while the crane is in a low position and with unfavourable meteorological conditions (stable atmosphere and weak wind). PS6-4.6

7 This extreme scenario has two main consequences to be taken into account: i) the delayed ignition of the cold natural gas cloud caused by such a spillage, ii) the thermal effects of the LNG pool fire. The simulations have been performed with dedicated tools for LNG, which had been developed in the past by Gaz de France and qualified by tests campaigns and third party expertises when used for safety studies. The results show that the test bench does not contribute an extra critical hazard to the current installations and terminal environment but this leads to restrictions for the dynamic test bench design and construction. Permitting Gaz de France has submitted to the local governmental representative (Prefect) the project to get the necessary authorisation to operate the dynamic test bench described below in the context of an LNG operating terminal classified as a SEVESO II industrial site under the European regulation. The local governmental representative considered the dynamic test bench as an extension of the Montoir-de-Bretagne terminal existing installations. Thus, the authorisation process had to follow the same steps than for a terminal. Following this administrative procedure, a prefectorial by-law has been obtained for a six months period with the possibility to renew it once. This by-law confirmed the conclusions of the safety study carried out by Gaz de France and detailed the design, construction, operation and safety aspects that must be taken into account by the project. MONTOIR OPU DYNAMIC TRIALS Dynamic tests objectives The dynamic test bench (see figure 6) has been designed to reproduce extreme severe offshore dynamic motion conditions. The objectives of the tests, which will be carried out on this dynamic test bench, are: To demonstrate the viability of the ALLS through the qualification of all the operating procedures and functionalities from sheltered areas to harsh environments. Therefore, three LNG transfer base cases have been selected: o Ship-to-shore / shore-to-ship LNG transfer in sheltered areas (see figure 2); o Ship-to-ship LNG transfer in side-by-side configuration in benign offshore environmental conditions (see figure 3); o Ship-to-ship LNG transfer in tandem configuration in harsh environmental conditions (see figure 4). To check the behaviour and the performances (thermal, hydraulic, mechanical ) of the system in real LNG transfer conditions. PS6-4.7

8 Eurodim patent pending Figure 2: Ship-to-shore configuration for sheltered areas ( Gerris architecture). Figure 3: Ship-to-ship LNG transfer in side-by-side configuration. Eurodim patent pending Figure 4: Ship-to-ship LNG transfer in tandem configuration ( Light Reel architecture). Dynamic test bench principles Dynamic motions. The dynamic test bench has been designed to simulate the most significant motions, which can occur at the LNG carrier connection point during the ALLS operations: PS6-4.8

9 Heave acceleration = 4m/s² max; Heave amplitude = ± 6.5 m max; Period = 8s. These motions correspond to the ALLS base case, stern to bow LNG transfer between two ships tandem moored in harsh environment i.e. a significant wave height of 5.5m. Vertical offset. To reproduce the vertical LNG carrier draught variations as well as tide variations, different positions of the mobile arm will be used to execute the tests in static conditions. Torsion. The maximum allowable torsion deflection of the flexible hose in static conditions is 0.6 /m and 0.3 /m in dynamic conditions, configurations which can occur in an emergency situation. To reproduce these conditions for the trials on the dynamic test bench, torsion will be applied to the flexible hose by rotation of one end fitting. Dynamic test bench location According to the safety study conclusions and by considering that the major scenario consequences should not lead to domino effects on the terminal installations, the test bench has been localised inside the dedicated test area. This leads to the following layout scheme for the whole installations of the dynamic test bench. Médiathèque Gaz De France Yves Blond Gaz de France Montoir-de-Bretagne LNG terminal bench dedicated test area test bench local control room Figure 5: Top view of the Gaz de France Montoir-de-Bretagne LNG receiving terminal and dynamic test bench location. PS6-4.9

10 Dynamic test bench description Supporting structures. The dynamic test bench is constituted of three supporting structures of 25 meters height, which are: Fixed end supporting structure (TS1): This structure allows the fixed connection of the LNG pipe to the flexible hose. A platform supports the handling equipment and allows access to the instrumentation; Handling and storage supporting structure (TS2): This structure allows storing the flexible hose in catenary s configuration and supports the storage and handling equipments (hydraulic winch). This structure has platforms to access the connecting system instrumentation or for maintenance work; Mobile end supporting structure (TD3): This structure is constituted of a mobile arm and the supporting structure itself. A hydraulic jack applies static and dynamic motions to the mobile arm thanks to a hydraulic power unit located at the 15 meters intermediate platform. The mobile arm supports a pull-in winch to allow connection and disconnection of the ERS mounted at the flexible hose end to the QCDC installed at the mobile arm extremity m m TD3 TS2 TS1 Figure 6: Dynamic test bench structures scheme. Cryogenic flexible hose. The main technical characteristics of the flexible hose to be tested are: Design Pressure: 10 barg; Length: 50 m Internal diameter: 16 Weight: 120 kg/m (empty) 186 kg/m (full of LNG) Minimum bending radius: 4.5 m (storage) Piping. The main characteristics of the pipes of the dynamic test bench are given below: PS6-4.10

11 LNG lines: The test bench has eighteen inches main LNG lines connected to the thirty-two inches LNG offloading header of the tank N 2 through specific flanges shown on figure 7. Purge lines: The purge line collector has a four inches diameter and is connected to the general purge network of the terminal; Utilities: The dynamic test bench is also connected to fuel gas, nitrogen and instrument air networks of the terminal. Figure 7: LNG flange connections. Power systems, equipment and instrumentation. Independent power supply; Hydraulic power units; Hydraulic winches; Flow-meter; Surface temperature probes; Pressure transmitters; CCTV s (Closed circuit TeleVision); Gas and fire detection; Moreover, numerous sensors have been installed on the test bench in order to collect all the necessary measurements for the qualification. Control room. To operate the test bench, collect the data and ensure a perfect coordination with the terminal, a dedicated local control room has been built for the test bench operators. Dynamic test bench construction The main objective during test bench construction was to minimize the impact on the terminal operations. It has so been decided to declare the whole area dedicated to the test bench as a closed and independent construction site with access through the terminal roads. This leads to a different regulation for the construction site, independent from the safety policy of the terminal and allow handling all the safety and health aspects without impact on the terminal. PS6-4.11

12 The photos here below (figure 8) show different steps of dynamic test bench structures construction. Figure 8: Dynamic test bench structures assembly (from top left to down right). Local control room and power supply Mobile arm ALLS LNG purge netw ork Main LNG pipes Figure 9: Dynamic test bench overview during construction. Dynamic test bench process The test bench can accept LNG flow in both directions related to two different LNG circulation modes as described below: PS6-4.12

13 Recirculation mode: The purpose of the recirculation mode is to keep the test bench in cold condition, in order to allow testing the connection, disconnection (including ESD and ERS sequences) and purge operations. Offloading mode: The purpose of the offloading mode is to test the transfer system with high LNG rates in order to measure pressure drops and flow induced vibrations. Pressure measurements will allow validating theoretical calculations or alternatively tuning the parameters used in theoretical calculations. The process flow diagrams (PFD) corresponding to the circulation modes principle are given below: TANK TANK RV 2 RV 1 UPSTREAM 1VB331 1VP46 BERTH 1VB92 1VB60 LP DISCHARGE SYSTEM 18" FT UNLOADING SYSTEM 1VB59 TO SEND-OUT SYSTEM PT 18"x16" TT 16" PT 18" TANK RV 3 ESD2 ESD1 18" TT 18" ESD1 TT TT 14" 14" DOWNSTREAM BERTH TANK TANK RV 2 RV 1 UPSTREAM 1VB331 1VP46 BERTH LNG CARRIER 1VB92 1VB60 LP DISCHARGE SYSTEM 18" FT UNLOADING SYSTEM 1VB59 TO SEND-OUT SYSTEM PT TT 16" PT 16" 18" TANK RV 3 ESD2 ESD1 18" TT 18" ESD1 TT TT 14" 14" DOWNSTREAM BERTH Figure 10: Recirculation mode (top) and offloading mode (down). According to the test program and operations to be carried out on the dynamic test bench, specific procedures related to the test bench process and ALLS operability have been developed. These procedures deal with all the necessary phases to operate ALLS and are split as detailed here below: Storage; Connection; Cooling down and filling with LNG; Stand-by in cold conditions; Purge and disconnection to storage position; PS6-4.13

14 Emergency disconnection; Access and handling. As the qualification activities include some items related to ALLS operability (see Qualification process HAZID), the procedures should demonstrate their reliability to operate the system in safe and repeatable conditions. Dynamic test bench operating conditions A dedicated Gaz de France team will operate the test bench from the local control room in close coordination with the terminal operators to ensure that any tests or actions do not conduct to an unsafe state for the test bench or the terminal process. Moreover, both ALLS LNG operators and terminal LNG operators have been trained on the other team respective installations to guarantee a sufficient knowledge of all the actors involved during the trials. Dynamic tests program The test program has been elaborated according to: Qualification activities to be performed and witnessed by DNV representative; Dynamic test objectives; LNG operators requirements; LNG standards requirements (OCIMF and EN1474) The resulting full-scale trials have then been detailed in order to fulfil all the objectives associated with the test program. The main phases are described here below: Ambient temperature tests: o Objectives: demonstrate the ALLS operability for: Connection/disconnection; Handling; Guiding and alignment; o Test conditions: Static (ship-to-shore base case); Dynamic (side-by-side and tandem configurations) With and without torsions LNG tests; o Objectives: validate the process operations; Connection; Cooling down; Purge; PS6-4.14

15 Disconnection; Storage; Emergency disconnection; o Test conditions identical than for ambient temperature tests; o Specific measurements: Pressure drops; Longitudinal and radial thermal gradients; Vibrations. Planning At the time this article is written, the installations described above are at the commissioning stage, which should end at the early beginning of 2007 and followed by the test program as given above. A full qualification of ALLS is thus expected in DYNAMIC TESTS KEY POINTS The main operating aspects to be checked during the dynamic qualification trials regarding the ALLS functional requirements for a future use in operation are: Overall performances; Safety; Operability in term of user-friendliness during handling, connection, purge and disconnection phases; Reliability (notably for emergency disconnection in dynamic conditions); Repeatability of the procedures whatever the conditions (static or dynamic); Maintenance. The dynamic tests should answer all the questions and get the LNG industry confident with the use of ALLS, which intend to be used as well for ship-to-shore or ship-to-ship LNG transfer (side-by-side and tandem mooring configurations) up to a significant wave height of 5.5 m. Here below, we will focus on three important aspects: i) purge, ii) emergency disconnection, iii) maintenance. Purge Purging and drainage of the flexible hose before disconnection has been identified as a failure mode of the transfer system during FEED phase. Therefore, the procedure has to demonstrate its efficiency according to the basic principles given above. As the flexible hose is in catenary configuration, gravity will not help to purge the system. Starting with the assessment and the fact that it will not be possible to guarantee full purging and inerting due to flexible hose bellows structures a specific procedure has been developed. PS6-4.15

16 This particular procedure will be tested few times in static and dynamic conditions according to the trial program. Its efficiency being a key point for the ALLS qualification, the test results will be fully analysed by DNV, which will witness the test on site. Emergency disconnection The connecting system has been designed for safe and reliable emergency disconnection with very minimal spillage (less than 2 litres for a 16 transfer system) thanks to the eccentric tandem butterfly valves geometry of the ERS. Even if the LNG spillage is a key point for operator safety and to avoid damage to the carrier, the whole system behaviour during emergency disconnection in dynamic conditions has to be checked in accordance with the following points: No mechanical stress appears at the end fittings of the system; No clash is observed between the structures and the flexible hose; Speed limiter located on the ERS slows the flexible hose lowering (speed of fall of 0.5 m/s) until the load is taken back by the handling cable; No dynamic oscillations appear; Flexible hose stays in catenary configuration. Maintenance Another important aspect for operators is the ability of the system to be easily inspected or repaired on site without involving huge means, which can be problematic in offshore conditions. As the purge procedure philosophy described above does not intend to fully purge and inert the flexible hose in normal operating conditions, another specific procedure for maintenance has been developed. Its basic principle is to lay down on the ground (or on a platform) the end part of the flexible hose with the connecting system and to sweep the system thanks to dedicated connections linked with the purge network to put the system in a safe state for inspection, maintenance or connecting system re-assembly after an emergency disconnection. Figure 11: Flexible hose end with connecting system on the ground for inspection (left), flexible hose lift test with cranes (right). PS6-4.16

17 CONCLUSION The development of innovative LNG transfer solutions, able to meet the needs for future coastal weather exposed onshore plants or real offshore installations, is necessary to support the LNG Industry growth. The LNG full-scale trials to be performed at the Gaz de France Montoir-de-Bretagne LNG receiving terminal on the Amplitude-LNG Loading System (ALLS) are the ultimate stage of this technology qualification. These trials correspond to operating conditions as close as possible from the ones the system has been designed for in term of performances and operability. The results should lead to a full qualification of ALLS and a Statement of Fitness for Service issued by DNV is expected according to the DNV-RP-A-203 recognized qualification procedure. In a more general overview, the ALLS has been designed to have operation thresholds for LNG transfer (up to 5.5 m in tandem configuration) always above mooring thresholds, this offloading system never being thus the limiting factor for the offshore LNG chains. It has to be said that the developments, certifications and qualification obtained on the ALLS have been made possible thanks to close partnerships between all the actors involved all along the LNG chains. This world first should bring the LNG Industry to be confident with the use of cryogenic flexible hose based transfer system for the next generation of LNG plants. REFERENCES CITED [1]. Key Cryogenic Components for Dynamic Marine LNG Transfer at Sea: Development and Tests Completed B. Dupont (Eurodim), P. Cox (Technip France), J.-C Garrigues (KSB-Amri) OTC [2] Cryogenic Flexible for Offshore LNG Transfer P. Cox (Technip France), J.-M Gerez (Technip France), J.-P Biaggi (Technip France Genesis) OTC [3] Innovative Architectures for Transfer at Sea Studied B. Lanquetin (Total), P.- L Lanteri-Minet (Gaz de France), B. Dupont (Eurodim) OTC [4] Full Scale Qualification Trials and Certification of the Amplitude-LNG Loading System P. Cox (Technip France), G. Rombaut (Gaz de France) 23 rd WGC PS6-4.17