Tank Storage Istanbul 11/2010 LPG loading operations management Agenda 1. General configuration of an LPG depot Flow metering considerations and requirements Health & Safety requirements Loading authorization and security systems management 2. Case study Presentation of an optimized supervisory and MECI automation and supervision system for the management of 14 LPG depots including 7 unmanned depots Presentation 09/11-2 1
Flow meter requirements LPG transactional bulk transfers can be carried out using standard volume or mass. LPG Custody Transfer measurement primary meter must meet an accuracy of 0.6% (OIML R117 - MID) Measure Accuracy depends on maintaining a single phase liquid flow through the flow meters Presentation 09/11-3 Flow (volume and mass) metering Volumetric flow metering (liters) PD meter, turbine meter Ultrasonic flow meter Mass flow metering Coriolis (kg, tons) Presentation 09/11-4 2
Flow (volume and mass) metering Benefits Primary measurement in volume (PD and turbine meters) Primary measurement in mass (coriolis meters) Lack of moving parts, no mechanical wear (coriolis) Disadvantages Liquid phase assurance: Pressure drop can cause vapor breakout (flash point) Mechanical wear due to poor lubricity of LPG (PD and turbine meters) Units conversion uncertainty problems (mass to volume, volume to mass) Difficult calibration with volumetric devices (coriolis) Vibration sensitivity (coriolis) Presentation 09/11-5 Volume conversion to Mass Conversion from mass to volume and calculation of standard volume require accurate knowledge of the properties of LPG mixtures. Mass =Volume * Density Density must be determined! 1- Using an on-line densitometer (expensive solution); the densitometer is directly connected to the flow computer 2- Using LPG conversion tables, 24E and 23E, (produced and published by The Gas Processors Association (GPA) under the designation TP25), or other standards. The electronic flow computer will convert the volume to standard volume V15 and will compute the transactionnal mass = V15 * D15 Presentation 09/11-6 3
Measurement by weighing full truck Presentation 09/11-7 Measurement by weighing full truck Benefits Primary measurement in mass Vapor phase measurement unnecessary Balance in weight easier Easy weighting instruments calibration Disadvantages Very expensive solution (weighting bridges, on-board weighting sensors) Tank trucks volume overfilling not controlled Tank truck traffic in the loading terminal heavier, more complex supervision system Safety problem; LPG gas retention on in weighting bridge installation gap Presentation 09/11-8 4
LPG flow meters operation requirements 1 - Loading arm and hose must be constantly full of product in service operation 2 - Liquid phase assurance; LPG gets a high Vapor Pressure. Pressure drop can cause flashing change to two phase conditions, which can distort the measure accuracy. LPG Vapor Pressure is a mathematical equation Antoine formula, Vapor Pressure in relative bar unit function of temperature: VP = exp(a-b/(c+t)))-1 Butane C4 H10 a:9,6382297 b:2321,2682 c:256,64 Propane C3 H8 a:8,8258087 b:1897,6525 c:262,79 Presentation 09/11-9 LPG flow meter requirements Vaporization depends on temperature and pressure of measured product How to maintain pressure and avoid vaporisation and maintain the liquid phase? Cooling the temperature of the LPG (expensive) Maintaining the LPG all over the pipe at a pressure higher than its own Vapor Pressure: Holding constant pressure though P > LPG Vapor Pressure at max service temperature Holding adjusted pressure though P > LPG Vapor Pressure + 1 bar (dynamic regulation) Presentation 09/11-10 5
Truck loading operation (1) LPG is pushed in the piping in order to: Cooling process Push out gas pockets To cool the piping installation in order to avoid gas formation during loading operation T Storage Presentation 09/11-11 Truck loading operation (2) The required quantity is pumped under pressure and loaded into the tank truck. In some configuration, the gas phase in the tank is either condensed or returned to the LPG storage. The site system or the batch controller control : The flow pressure regulation The flow rate regulation Storage Presentation 09/11-12 6
Tank unloading operation (1) Gas phase of the storage is used to push out the liquid of the tank truck Empty tank gas recovery Gas phase Liquid phase Storage Presentation 09/11-13 Tank unloading operation (2) The direction of the compressor is inverted in order to recover the gas phase of the tank truck. 2) Gas phase recycling Gas Storage Presentation 09/11-14 7
H&S requirements - Overall LPG site General site gas, flame and smoke detections (emergency alarms) Synchronization of the valves and pump status (emergency shut down valves) Over & under pressure sensors Overflow probes Tanks level control Presentation 09/11-15 H&S requirements - LPG loading position Loading arm safety break Loading arm settled valve Loading arm pressure switch Vehicle grounding system Overfilling detection sensors Dead-man control Metering defaults Presentation 09/11-16 8
H&S requirements - operator cabinet Truck overfilling sensor: In addition to visual rotating gauge, tank truck can be equipped of an overfilling sensor (optical, magnetic, radar) The safety control system automatically stops the filling process when the overfilling level is reached Dead Man safety device: At a regular time interval, the operator must manifest its presence on the site actuating the dead - man device. In case of non presence action, a sound alarm is actuated. If the situation last, the general safety alarm is actuated for the site safety and alarm to safety services Earthing connection; A specific grounding control device does not allow loading operation if not connected Presentation 09/11-17 Case study : Optimization of metering, automation and supervisory for LPG depots 9
Overview Final user Location A French Major Oil Company France Application -Supervision and automation of 15 butane, propane & LPG depots including 7 unmanned facilities (without permanent employee) -Automation of loading & unloading of LPG, butane, propane local and distant tank farm supervision, remote maintenance Presentation 09/11-19 Overview Headquarters Main depots Unmanned depots Presentation 09/11-20 10
Overview Headquarters Remote maintenance Possibility to control all the depots Stock reconciliation in mass Main depots 150 à 500 m3 Supplied by rail or tank trucks Unmanned depots 100 m3 maxi Supplied by tank trucks Controlled by related main depot Presentation 09/11-21 Overview: unmanned depot Access control for trucks and drivers Operator cabinet Loading area Unloading area Operator cabinet Presentation 09/11-22 11
Depot access control Driver identification Biometric identification at the inlet of the depot Fingerprint readers are used to allow only accredited drivers to enter the facility Presentation 09/11-23 Depot access control Trucks identification at the inlet of the depot Semi passive tag technology Microwave based communication The tag echoes its identification code when receiving a 2.45 GHz carrier emitted by the antenna Hand free detection Presentation 09/11-24 12
Loading operations : operating procedure The driver is identified via a smart card reader The driver key-in loading data via MMI - mass preset value and medium - Actual tank filling rate -Truck plate number The system calculates and display the maximum allowed quantity to be loaded The driver must then connect security devices (grounding system, tank level switch) He will then be allowed to press the Dead-man & the Start loading buttons Presentation 09/11-25 Loading operation : operator cabinet Total mass display Card reader Emergency stop button Tank truck level detection Man Machine Interface Start loading button Grounding detection Dead-man detection Presentation 09/11-26 13
Metering systems 1-Measuring system with turbine meter -Measurement of volume at operating pressure & temperature -Measurements of operating pressure and temperature -Calculation of operating density from P, T & API MPMS 11.2.2.M table -Calculation of masse Advantage: Easy to calibrate (volume against ball prover, P, t) Weak point: Not a direct mass measurement Can lead to error if product quality is not constant Presentation 09/11-27 Metering systems : ball prover calibration Presentation 09/11-28 14
Metering systems 2-Measuring system with massflowmeter Advantage: Direct measurement of mass No need for P & T custody transfer approved measurements Weak point: Calibration against prover needs also measurement of reference density Presentation 09/11-29 Metering system: typical mass metering skid Massmeter converter Massmeter transducer Motor valve Control valve for line pressure adjustment Presentation 09/11-30 15
Metering systems : flow computer (FC) functionalities 1-Calculation of loaded quantities, batch control, transactions data storage, 2-Blending control for LPG preparation The driver enter the quantity of LPG to be loaded The FC calculates the quantities of butane and propane to be loaded The batches of butane and propane are loaded successively 3-Communication Presentation 09/11-31 Metering systems : flow computer functionalities 4-Additive injection control Injection of ethyl mercaptan for odour or of proprietary compounds for road fuels 5-Line pressure control The FC calculates the saturation pressure of LPG from P & T measurements It defines a pressure set point (Psat + 1 bar) controlled by control valve 6-Calibration operation management Presentation 09/11-32 16
Automation and supervisory system functionalities 1-Automation of loading and unloading operations Management of loading/unloading cycles Loading authorization according to company quotas Security devices management 2-Communication with the truck driver Operating instructions, error and warning messages 3-Communication with headquarters and dispatching Presentation 09/11-33 System architecture for main depot Supervisory PC and data base Remote maintenance PSTN Printer Truck indentification Badge reader PLC Printer events Printer Bill of lading Fingerprint reader Sécurity dev. Presentation 09/11-34 17
System architecture Presentation 09/11-35 Thank you for your attention, Q & A???? Presentation 09/11-36 18