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1
Tank Storage Istanbul
11/2010
LPG loading operations
management
Presentation – 09/11 - 2
Automation & metering solutions
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
Agenda
2
Presentation – 09/11 - 3
Automation & metering solutions
• 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
Flow meter requirements
Presentation – 09/11 - 4
Automation & metering solutions
• Volumetric flow metering (liters)• PD meter, turbine meter• Ultrasonic flow meter
• Mass flow metering Coriolis (kg, tons)
Flow (volume and mass) metering
3
Presentation – 09/11 - 5
Automation & metering solutions
• Primary measurement in volume (PD and turbine meters) • Primary measurement in mass (coriolis meters)• Lack of moving parts, no mechanical wear (coriolis)
• Primary measurement in volume (PD and turbine meters) • Primary measurement in mass (coriolis meters)• Lack of moving parts, no mechanical wear (coriolis)
BenefitsBenefits
• 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)
• 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)
DisadvantagesDisadvantages
Flow (volume and mass) metering
Presentation – 09/11 - 6
Automation & metering solutions
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
Conversion from mass to volume and calculation of standard volume require accurate knowledge of the properties of LPG mixtures.
Volume conversion to Mass
4
Presentation – 09/11 - 7
Automation & metering solutions
Measurement by weighing full truck
Presentation – 09/11 - 8
Automation & metering solutions
• Primary measurement in mass • Vapor phase measurement unnecessary• Balance in weight easier• Easy weighting instruments calibration
• Primary measurement in mass • Vapor phase measurement unnecessary• Balance in weight easier• Easy weighting instruments calibration
BenefitsBenefits
• 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
• 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
DisadvantagesDisadvantages
Measurement by weighing full truck
5
Presentation – 09/11 - 9
Automation & metering solutions
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 equationAntoine 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
LPG flow meters operation requirements
Presentation – 09/11 - 10
Automation & metering solutions
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)
LPG flow meter requirements
6
Presentation – 09/11 - 11
Automation & metering solutions
LPG is pushed in the piping in order to:
Push out gas pockets To cool the piping installation in order to avoid
gas formation during loading operation
T° Storage
Cooling process
Truck loading operation (1)
Presentation – 09/11 - 12
Automation & metering solutions
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 regulationThe flow rate regulation
Storage
Truck loading operation (2)
7
Presentation – 09/11 - 13
Automation & metering solutions
Gas phase of the storage is used to push out the liquid of the tank truck
Empty tank gas recovery
Liquid phase
Gas phase
Storage
Tank unloading operation (1)
Presentation – 09/11 - 14
Automation & metering solutions
The direction of the compressor is inverted in order to recover the gas phase of the tank truck.
2) Gas phase recycling Gas
Storage
Tank unloading operation (2)
8
Presentation – 09/11 - 15
Automation & metering solutions
• 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
H&S requirements - Overall LPG site
Presentation – 09/11 - 16
Automation & metering solutions
• Loading arm safety break
• Loading arm settled valve
• Loading arm pressure switch
• Vehicle grounding system
• Overfilling detection sensors
• Dead-man control
• Metering defaults
H&S requirements - LPG loading position
9
Presentation – 09/11 - 17
Automation & metering solutions
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
H&S requirements - operator cabinet
Case study :
Optimization of metering,
automation and supervisory
for LPG depots
10
Presentation – 09/11 - 19
Automation & metering solutions
2-Case study : Automation of loading & unloading stations
Overview
Final user A French Major Oil Company
Location 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 - 20
Automation & metering solutions
Overview
Main depots
Unmanned depots
Headquarters
2-Case study : Automation of loading & unloading stations
11
Presentation – 09/11 - 21
Automation & metering solutions
Overview
Main depots 150 à 500 m3Supplied by rail or tank trucks
Unmanned depots 100 m3 maxiSupplied by tank trucksControlled by related main depot
Headquarters Remote maintenance Possibility to control all the depotsStock reconciliation in mass
2-Case study : Automation of loading & unloading stations
Presentation – 09/11 - 22
Automation & metering solutions
Overview: unmanned depot
Operator cabinet
Access control for trucks and drivers
Operator cabinetLoading area
Unloadingarea
2-Case study : Automation of loading & unloading stations
12
Presentation – 09/11 - 23
Automation & metering solutions
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
2-Case study : Automation of loading & unloading stations
Presentation – 09/11 - 24
Automation & metering solutions
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
2-Case study : Automation of loading & unloading stations
13
Presentation – 09/11 - 25
Automation & metering solutions
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
2-Case study : Automation of loading & unloading stations
Presentation – 09/11 - 26
Automation & metering solutions
Loading operation : operator cabinet
Card reader
Man – Machine Interface
Dead-man detectionGrounding detection
Tank truck level detection
Emergency stop button
Total mass display
“Start loading” button
2-Case study : Automation of loading & unloading stations
14
Presentation – 09/11 - 27
Automation & metering solutions
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
2-Case study : Automation of loading & unloading stations
Presentation – 09/11 - 28
Automation & metering solutions
Metering systems : ball prover calibration
2-Case study : Automation of loading & unloading stations
15
Presentation – 09/11 - 29
Automation & metering solutions
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
2-Case study : Automation of loading & unloading stations
Presentation – 09/11 - 30
Automation & metering solutions
Metering system: typical mass metering skid
Massmeter transducer
Massmeter converter
Control valve for line pressure adjustment
Motor valve
2-Case study : Automation of loading & unloading stations
16
Presentation – 09/11 - 31
Automation & metering solutions
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
2-Case study : Automation of loading & unloading stations
Presentation – 09/11 - 32
Automation & metering solutions
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
2-Case study : Automation of loading & unloading stations
17
Presentation – 09/11 - 33
Automation & metering solutions
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
2-Case study : Automation of loading & unloading stations
Presentation – 09/11 - 34
Automation & metering solutions
System architecture for main depot
Remote maintenanceSupervisory PC and data base
Truck indentification
Badge reader
Fingerprintreader
PLC
Printer
Printer events
Printer Bill of lading
PSTN
Sécurity dev.
2-Case study : Automation of loading & unloading stations
18
Presentation – 09/11 - 35
Automation & metering solutions
System architecture
2-Case study : Automation of loading & unloading stations
Presentation – 09/11 - 36
Automation & metering solutions
Thank you for yourattention,
Q & A ????