1. business and industrial
2. energy
3. natural gas

LNG SAMPLE VAPORIZER
ISOSAMPLE 8100
for ON LINE GC SAMPLING
Recording Q/N : 0808647 Rev 0
Contractor :
Project: To be specified
Q/N: 0808647
OPTA-PERIPH
1
LNG SAMPLING SYSTEM
DATE
14/08/2008
REV.
0
1.0
INTRODUCTION
This Quotation defines the TECHNICAL CHARACTERISTICS of the ISO 8100
LNG Sampling System for the xxxx loading Plant.
The online system for LNG is composed of an efficient online sample probe and a
vaporizer. This device can be provided together with any existing online Gas
Chromatograph for LNG. Additionally a sampling system (preferably automatic) is
generally installed to collect samples for the purpose of laboratory measurements
by contractors and third party.
The sample probe and vaporizer are the key elements to ensure integrity of the
sample and to obtain the performance of accuracy with 9.0 kJ/kg Gross Calorific
Value and 3.0*10 -4 kg/m3 Density maximal random error.
When a sampling is required, the holder cylinder described in this quotation is a
prerequisite for compliance with existing standards.
The first part of system is the sample take-off probe:
2.0
CODES & STANDARDS:
The probe vacuum isolated and the vaporizer are complying with following
standards:
- Sample probe resonant frequency calculation:
-BS IEC 61831:1999 for on line velocity <7 m/s
-API RP 551 for on line velocity > 7 m/s
-Main welding test: APAVE certified under CODAP 2000- Rev 04-04-IA4--ASME
V- APIRP 551
- Probe subcooling degree calculation: ISO 8943-2007
-Vaporizer :- capacity calculation: ISO 8943-2007
- Ex-proof ATEX II 2G EExde II C T4
THI
- Probe & vaporizer pressure test: PED 97 23 EC - calculations approved Bureau
Veritas
- Suitability testing of discontinuous sampling with lab and process GC by supplier:
EN 12838- Class A of accuracy with 54 kJ/kg Gross Calorific Value and 18*10 -4
kg/m3 Density maximal random error.
- Suitability testing of continuous sampling with ISOSAMPLE 8100 piston cylinder
holder and process GC by supplier: EN 12838- Class A of accuracy with 9.0 kJ/kg
Gross Calorific Value and 3.0*10 -4 kg/m3 Density maximal random error.
OPTA-PERIPH
2
LNG SAMPLING SYSTEM
DATE
14/08/2008
REV.
0
3. 0
SAMPLE TAKE - OFF PROBE PRINCIPLE:
The sample take-off is composed with a probe inserted directly at the centre of the LNG
product pipe, double isolating valves, and a capillary tube carrying the LNG sample from
the probe towards the vaporizer (see Figure 0-1).
Figure 0-1: Picture of the ISO 8100 sample probe
This probe has been designed to provide a Thermal insulation of the sample takeoff probe by high vacuum maintained below 1.10-4 torr.
THI
The conjunction of this ultra-low residual pressure minimizing heat leak by
conduction and convection with layer of radiation shields cryogenic constitutes a
super insulation system providing apparent thermal conductivity (k) values below
0.4 milliwatt per meter-kelvin (mW/m-k), therefore the enthalpy rise can be
controlled to be inferior of the subcooling degree and fractionation will not have
occurred in the sampling line. The annexure 1 of this document determines the
degree of subcooling reproduced from the ISO 8943 standard compared to the
performances of the ISO 8100 Sample probe.
4.0 VAPORIZER PRINCIPLE:
The LNG sample has to be totally vaporized before being sent to the online Gas
Chromatograph. In particular heavy components of the LNG shall not remain in the
vaporizer. In the ISO 8100 device, vaporization is made in supercritical state,
eliminating the risk of fractioned vaporization. There are two important points
related to the phase envelope, namely Cricondenbar and Cricondentherm. These
points represent respectively the maximum pressure point and temperature point
at which the LNG exists in two phases.
Figure 0-2 here under displays the pressure/temperature diagram for a LNG
containing approximately 90% methane, where:
OPTA-PERIPH
3
LNG SAMPLING SYSTEM
DATE
14/08/2008
REV.
0
B
T
C
Cricondenbar, in bar
Cricondentherm, in °C
Critical point, in bar
Figure 0-2: Pressure/Temperature Diagram
The objective is then to transform LNG from liquid to gas state in supercritical
conditions at very high pressure (here above 75 bars), such that the LNG sample
goes directly into the desired gas state. Such transformation is represented on
Figure 0-2 by the dotted line.
THI
Within the ISO 8100 sample probe and vaporizer, the following operations are
taking place (see Figure 0-3):
• The temperature rises from -160°C to -150°C in the capillary tube, at LNG
process pressure (minus some pressure drops in the sample line)
• A supercritical cell featuring pressure reductor/check valve integrated at the
inlet of vaporizer coil has been designed for flashing at that point the liquid sample
without back pressure effect to process line
• The vaporization in this cell (indicated as "critical point in the figure 2-4) of
approximately 0.5 cc increases the temperature and the pressure, and leads to
conditions of approximately 80 bars and -100°C
• The temperature is controlled at +65°C in the vaporizer, in order to obtain
approximately +55°C at the outlet of the vaporizer
OPTA-PERIPH
4
LNG SAMPLING SYSTEM
DATE
14/08/2008
REV.
0
Figure 0-3: Sample probe/Vaporizer profile
THI
Similarly to the sampling probe, no fractioned vaporization is taking place in the vaporizer,
ensuring that the required sample quality and stability is maintained carefully before
being sent to the Gas Chromatograph.
OPTA-PERIPH
5
LNG SAMPLING SYSTEM
DATE
14/08/2008
REV.
0
5.0 SYSTEM DESCRIPTIVE:
First segment probe:
The sampling probe must be located on the top of horizontal part of pipe to
withdraw the LNG from a penetration in pipe. The probe is designed with variable
diameter for non resonant compliance .
This tube constitutes the external part of the vacuum jacket downside the flange,
the Internal sampling tube is sized 1/8" OD .
The flange item 2 is sized 2 to 4" 150 to 600 LBS according to the user
requirements and the upside vacuum jacket item 15 is welded on flange and
assembled with high vacuum flanged connections.
3
15
2
Diagram 3
THI
A first sample isolation core valve item 3 is supplied and encapsulated in the
vacuum jacket, this valve is only accessible by opening the flange cap to isolate
the system from pipeline if any maintenance work is required, thus, the
downstream part of system can be removed and the vacuum re-established in this
pre-insulation section without process service disturbance such as outage of the
loading line.
A valve drive special tool is supplied with the probe.
Second segment probe:
A capillary assembly item 4 is provided for breaking equilibrium between the
sample and pipeline pressures and the main isolating actuated valve item 5 is
supplied with extended bonnet and pneumatic actuator item 9.
This actuator is operated via the Control unit installed near of the vaporizer
cabinet to switch ON/OFF the valve (normally closed) automatically for alarm or
manually.
The valve is automatically turned OFF if the temperature TT5 at outlet of
vaporizer is dropping below - 20°C because of vaporizer failure.
OPTA-PERIPH
6
LNG SAMPLING SYSTEM
DATE
14/08/2008
REV.
0
5
4
Diagram 4
9
The check valve item 7 located on critical point ( refer to Fig 2-4) is operating as
pressure barrier between the liquid/vapor phases e.g: critical point (at which the
liquid state of LNG ceases to exist).
Temperature measurement transmitter thermocouple K item TT2 (with 1 meter
coil in the vacuum jacket to avoid heat leak by conduction) is provided
downstream of the check valve at the inlet of vaporizer coil where the sample is
transformed from liquid to gas phase between -80 and -130°C approx.
3.
VAPORIZER:
The coil exchanger item 16 is a 2m x 3 mm ID
tubing and the assembly is so constructed for
providing sample flushing to avoid fractionated
distillation effect and the heavier components of
the LNG will not remain in the coil.
Three temperature points are monitored:
TT2: thermocouple K Transmitter: measuring
the inlet temperature of LNG, a 1 m extension
capillary is provided in the vacuum jacket for
thermal insulation.
TT3:PT100 (inserted in well item 16) measuring
the heat exchanger temperature controlled by
Application PC Controller.
TT5: pneumatic thermoswitch measuring the
natural gas at outlet.
TT5
THI
.
TT2
OPTA-PERIPH
7
LNG SAMPLING SYSTEM
DATE
14/08/2008
REV.
0
All these signal temperature are entering in the Control unit for processing the
application.
An high temperature trip switch TAH4 calibrated at 135°C for class T4 is supplied
for safety redundancy and a pressure alarm pneumatic switch PT4 is supplied as
well on natural gas at outlet of vaporizer.
The Control Unit provides a temperature control of exchanger TT3 at 65°C plus
a temperature interlock system for auto-shut-off sample take-off valve if outlet
temperature T5 drops to -20°C ( normal is +55 °C) or if pressure at vaporizer
outlet exceeds 8 bar-g.
As per our recommendation a fast loop Mass Flow Controller FIC1 can be
supplied by the GC sampling integrator upstream of the GC; this MFC can be
processed from our Control Unit to control the TT2 temperature at coil inlet
below -75°C, range of flow rate is between 1 000 and 1500 SL/H.
The capacity of the LNG vaporizer has been designed to gasify the whole volume
of LNG which is being withdrawn for sampling
For this application the subcooling degree compliance has been calculated for a
total gas vaporized volume of 1 000 SL/H.
Vaporizer integration:
The vaporizer is contained in a
stainless steel cabinet, protecting
code is ATEX II 2G EEx de IIBT4
and heating capacity is 0.5 kW.
The actuated valve local manifold is
contained in the box item 02.
The other items are :
-item 01: inter-connection box
-item 03: temperature transmitter
TT2
-item 04: temperature transmitter
TT5
-item 05: absolute pressure
transmitter PAL2.
THI
The vaporizer cabinet is mounted
on the probe frame tied to the pipeline.
OPTA-PERIPH
8
LNG SAMPLING SYSTEM
DATE
14/08/2008
REV.
0
4-.
CONTROL UNIT & PNEUMATIC LOGIC:
The Control Unit provides a temperature
control of exchanger TT3 at 65°C plus a
temperature interlock system for auto-shutoff sample take-off valve if outlet
temperature TT5 drops to -20°C ( normal is
+55 °C) or if pressure at vaporizer outlet
exceeds 8 bar-g.
As per our recommendation a fast loop
Mass Flow Controller FIC1 can be supplied
by the GC sampling integrator upstream of
the GC; this MFC can be processed from
our Control Unit to control the TT2 temperature at coil inlet below -75°C, range of
flow rate is between 1 000 and 1500 SL/H.
- A Pneumatic logic controller of sample probe valve is
provided integrating:
. manual valve on/off
. remote pneumatic on/off valve control
. automatic valve shut-off if TS5 < -20°C
. automatic valve off-off if pressure alarm > process
pressure + 10 bar-g
5-.
ASSEMBLY of PROBE/VAPORIZER:
Sample probe must be installed at point in the pipeline
where the LNG is in a subcooled condition. The two
segments of Probe and the vaporizer must be flanged
vertically on top side of pipe line with the vaporizer
enclosure supported on same axis.
As option a probe/vaporizer mounting frame is supplied and
the bellows supplied on the probe second segment allows a
line taping moving of +/- 45 mm from axis. The control unit
and pneumatic logic plate assemblies are mounted and fully
distributed on frame.
THI
Vacuum generation:
On original start-up , the vacuum generation inside of the
jacket is operated with an eductor supplied as option.
OPTA-PERIPH
9
LNG SAMPLING SYSTEM
DATE
14/08/2008
REV.
0
Mounting frame on
pipeline
Control unit with
isolator Plate assembly
Pneumatic logic Plate
assembly
6-.
MAIN SPECIFICATIONS:
Pipe-line pressure: 2 to 10 bar-g
Design pressure: 18 bar-g
Pipe-line temperature: - 160 °C
Volume of gas sample vaporized: approx 1000 Sl/h
Lag time through sampling probe and vaporizer: 30 sec approx.
Thermal conductivity of probe: 0.4 milliwatt per meter-kelvin (mW/m-k)
THI
Heating capacity of vaporizer: 0.5 Kw
Sample outlet connection: 1/4" NPTF
Protecting electrical code: ATEX II 2G EEx de IICT4
Enclosure rating: IP65 or NEMA 4x
50
OPTA-PERIPH
10
LNG SAMPLING SYSTEM
DATE
14/08/2008
REV.
0
7-.
BILL OF MATERIAL:
THI
1-SAMPLE TAKE-OFF PROBE
-High vacuum
-Integrating the core encapsulated valve item 3 and the actuated valve item 5 normally
closed
-Pneumatic actuator of shut-off valve
-Bellows on the probe second segment for probe axis taping moving of +/- 45 mm.
-Vacuum jacket isolation by auto-opturation valve at inlet and vacuum valve at outlet .
-Flange Type: RF Flange or other as specified
-Rating:300lb or other as specified
-Size :2" ANSI or other as specified
Maximum process pressure: 16 barg as standard or 150 barg for the high pressure
model
-Sampling tube diameter and length determined for non resonant compliance
-Orientation: on top
-Material: all parts in S S 316L.
.
Options:
1- Dual pitot inlet orifice for direct and reverse flow sampling
2-Vacuum gauge ranged -1 to 3 bar-g
3- Air vacuum jet ejector fitted on vacuum valve (only one air ejector required for all the
LNG PROBES of the plant)
4- Mounting frame on the process flange: material in SS 304 ; this option is to line-up the
probe and vaporizer on process flange
5- Mouting of Control Unit and Pneumatic Logic on frame with complete pneumatic and
electric distribution
Note: the weight of probe / vaporizer to be added to stand weight is 95 Kg.
II:LNG VAPORIZER / CONTROLLER:
- Vaporizer to be flanged at the extremity of sample probe spool.
- Power supply: 240 VAC - 50Hz
- Heating Capcity:500 Watts
- Classification:ATEX II 2G EEx de IICT4
-Maximum process pressure: 150 barg
- Cabinet Material:304 Stainless Steel
- Monitoring of three temperature points:
TS 1: thermocouple K: measuring the inlet temperature of LNG, extension capillary is
provided in the vacuum jacket for thermal insulation.
.TS2:PT100 measuring the vaporizer heat exchanger temperature
.TS 5: pneumatic temperature switch : monitoring the natural gas at outlet.
-As safety redundancy an high temperature trip switch ,calibrated at 135°C for class T4
is integrated in the vaporizer heater block.
- Pressure alarm pneumatic switch fitted on the natural gas at outlet
- Pneumatic logic controller of sample probe valve integrating:
. manual valve on/off
OPTA-PERIPH
11
LNG SAMPLING SYSTEM
DATE
14/08/2008
REV.
0
. remote pneumatic on/off valve control
. automatic valve shut-off if TS5 < -20°C
. automatic valve off-off if pressure alarm > process pressure + 10 bar-g
III-TEMPERATURE CONTROL UNIT integrating:
. Vaporizer PID temperature indicator controller:0 to 100 °C (usual set point: 65°C)
. TS1 température indicator
. Protection: ATEX II 2G EEx di IICT6
. Enclosure in aluminum painted
. Power supply: 240 VAC - 50Hz & 24 VDC
Option for Exd 24 VDC generation if not available on site
Delivery: 24 weeks after order receipt
THI
IV- SAMPLING RECOMMENDATIONS:
At outlet of vaporizer in by-pass to BOG line, the flow-rate is to be controlled at 1000
SL/H, this is not included in our quotation.
Sampling system supplied by other shall involve a Mass Flow Controller type
EMERSON BROOKS Type 5816N/36 EX (item 1 in the typical spot sampling diagram
attached) the optimized process control is to control the flow from 1000 to 1500 SL/H in
order to keep the temperature TS1 at the lowest value achievable (usually between -130
to -80°C).
The vaporizer has been designed for a maximum flow-rate of 2000 SL/H.
OPTA-PERIPH
12
LNG SAMPLING SYSTEM
DATE
14/08/2008
REV.
0
LNG AUTOSAMPLER ISOSAMPLE
THI
for AUTOMATIC FILLING of LABORATORY CYLINDERS
OPTA-PERIPH
13
LNG SAMPLING SYSTEM
DATE
14/08/2008
REV.
0
1.0
INTRODUCTION
This Quotation defines the TECHNICAL CHARACTERISTICS of the ISO
8100 LNG Sampling System.
This supply is related to the LNG Charge Continuous AutoSampling System
for waterless-type gas sample holder as recommended in the latest version
of ISO 8943-2007 :
The system features the waterless-type sample holder recommended and
this unit (typically described with rubber membrane in the ISO standard )
is built within the Constant Pressure/Floating Piston (CP/FP) principle far more
robust with a guarantee of 5 years operation without maintenance.
As well the CP/FP cylinder is treated with sulfur passivation for samples
containing sulfur substances to be analysed .
Notes:
Charge autosampling is related to grabbing operated during full unloading operation, thus, the
sample collected is representative of complete transfer.
It has been assumed that the requisition is not for Intermittent sampling for CP/FP sample
container not dedicated to charge sampling application but spot autosampling. Intermittent
sampling requires a cleaning procedure of containers ( para B.4.1 of ISO 8943/2007) involving
trace gas analysis too heavy for useful operation.
2.0
ARCHITECTURE OF SYSTEM
THI
The system involves the Probe vaporizer quoted in the first section, the
Autosampler Model 8100 installed in a shelter near from the GC and the
software implemented in the Application PC controller.
Two control architectures can be supplied:
Sampler Application Controller is a PC in control room (safe area) with local
multiplexer / screen for zone 1 area (represented on diagram 1).
Or
Sampler Controller is a PLC supplied for zone 1 area.
50
OPTA-PERIPH
14
LNG SAMPLING SYSTEM
DATE
14/08/2008
REV.
0
In both cases Sampler Controller features a MODBUS or OPC data-link to
customer DCS.
Additionally, data's acquisition and fast loop flow-control of existing Probe
vaporizer (Cegelec) is provided as well as GC (Emerson) data's acquisition
for statistics and validation of complete system at the end of unloading.
3. 0
SAMPLE TAKE - OFF PROBE SUPERVISION:
Sample vacuum thermal isolation probe with cryogenic valve is
installed at point in the pipeline where the LNG is in a subcooled
condition. The degree of subcooling at a sampling point will be
ascertained by observation of the temperature and pressure of the
LNG at that point and comparing the temperature with the B.P. of the
LNG at the same pressure as calculated from the composition of the
LNG. It has been assumed that the pipeline temperature TT1, flowrate FI1 and pressure PT1 sensors/transmitters in pipe-line at
sample take-off are supplied by others .
4. 0
CONTINUOUS CHARGE AUTOSAMPLING SYSTEM:
A Charge aggregate autosampling system is provided with
automatic/manual interchange sequential control system as well as
time programmed automatically purging and filling for complete
unloading transfer sampling.
The sampling start up automatically when the monitored pipe-line flow
rate (FI1) reaches the nominal programmed value according to the
ISO 8943/2007 para 7.2 "Consecutiveness of sampling "and sampling
is operated from flow stabilisation to decresed flow rate before end of
transfer. Suspension of sampling for sudden change in flow rate is
auto-operated according to para 7.3. Bombs are filled in duplicate;
and usually , 2 bombs of 0,5 litres each are supplied per stream
sampled. The grab procedure is automated by the PC Controller.
4.1 Mass Flow Controller: FIC
THI
Usually two FIC are provided in the
system:
1-FIC1 (not included in this quotation)
controls the vaporizer fast loop flowrate returning to the BOG line.
The flow set point is controlled by the
Application PC controller : minimum
set point of 1000 Sl/h to comply with
subcooling degree requirement can be
increased up to 1800 Sl/h if the
temperature TT2 expected to be at -80
°C at vaporizer coil inlet is rising .
Would this function been unable to
return to cooling conditions , the
vaporizer temperature controller set
point is changed from 65 to 20 °C.
OPTA-PERIPH
15
LNG SAMPLING SYSTEM
DATE
14/08/2008
REV.
0
2- FIC2 is provided for controlling the flow to the charge holder cylinder at 3 to 10
SL/H (refer to annex 2 on base of 6 to 12H unloading)
To compensate the Joule-Thomson effect, the autosampler cabinet is electrically
heated.
4.2
Back Pressure Regulator: item 18-1
The pressure at outlet of vaporizer is the
same than on pipe-line pressure usually
between 2.5 and 6 barg.
The gas flow-rate on fast loop controlled
by the FIC1 is released to Marine vapor
recovery line header.
This back pressure regulator function is
only for safety and set point is adjusted at
8 barg.
4.3
System inerting manifold:
to GC
from
vapo
THI
He
Inerting manifold is automatically
operated at the first commissioning
sampling to remove any trace of air
in the system or further to a
maintenance operation with material
dismounting.
As well this inerting function can be
involved in the plant fire prevention
procedure.
to
sampling
OPTA-PERIPH
16
LNG SAMPLING SYSTEM
DATE
14/08/2008
REV.
0
5.
CHARGE HOLDER CYLINDER:
One constant pressure floating piston (CF/FP)
holder is installed between vaporizer and charge
portable sampling containers train
For this application the holder cylinder volume has
been designed at 25 L
The holder piston cylinder features PTFE seals double
piston barrier with a piston scrapper to auto-clean the
cylinder polished wall between two samplings.
Original purging is compliant with the ISO 8943-2007
section 6 6 4 and 7.4.1-d : this purging is made
through the piston shaft bore .
On the "ISOSAMPLE 8100" this procedure is fully
automated: the buffer gas chamber been pre
charged by compressed air with piston in down
position, the sample chamber is reduced to the
nominal zero volume before of sampling. Then the
sample purge valve is actuated to open for purging
the tiny dead volume between piston/end plate
through the piston shaft venting to atmosphere. For a
sampling line from vaporizer of 30 m with 3 mm ID
tubing electropolished a purging cycle of 1min
(programmable) is operated, then the purge valve is
closed.
Level transmitter is provided for comparison of calculated and
actual sample level in the holder or for indication of level when
the air motive pressure is to be decreased to a smaller value
consecutively to a pressure drop in line below 2.5 barg.
THI
- During grabbing cycle, the system is controlling a time
proportional charging of the holder piston cylinder during a period of
6 to 12H (programmable according to cargo size) .
The Mass flow controller FIC2 set point is controlled by the
Application PC Controller for adjusting in continuous this proportional
charging from 6.75 SL/H (for 6H transfer period ) to 3.375 SL/H (for
12 period) .
The loading pressure of floating piston holder is controlled at 1.5 barg (1 barg below the minimum process expected pressure) for
charging but in case of process press dropping below the 2.5 barg
minimum expected pressure, the loading pressure of floating piston
holder is re-adjusted at process pressure less 1 barg.
- At the end of each grabbing period , the holder piston cylinder
supposed to store 40.5 SL of gas under 1.5 barg (corresponding to
a volume of 16.2 L in the holder) is automatically isolated and
connected to the charge portable containers circuit for loading a
OPTA-PERIPH
17
LNG SAMPLING SYSTEM
DATE
14/08/2008
REV.
0
new couple of containers.
- The couple of charge containers are loaded during the unload
transfer of 10 to 12 H , then the system is stopped waiting for
operator new cycle validation once the charge containers have been
collected and replaced in the rack .
The loading pressure of floating piston holder is controlled at 1.5 barg for charging (if process pressure does not drop below 2.5 barg)
and at 4 bar-g for purging + end charging the portable containers.
For motive air insulation, the holder piston cylinder features interseals
chamber to be filled with a tiny volume of Helium. A small pressure
helium ( below 80 g/cm2g) will be controlled..
The LNG Sampling holder capacity is 25L to comply with the sum of
the volume required for charging the charge portable cylinders and
additional volume required for purging cycle (refer to calculations
annex 2).
The number of purging cycle will be as per annex D of ISO 10715
and Appendix C of ISO 8943-2007defined according to the final
pressure in cylinder : i.e: 8 cycles (programmable) at 4 Kg/cm2g.
CP/PF holder loading pressure control:
THI
The pressure inside of holder
is monitored by the PT5
transmitter and the Application
PC Controllers operates the
charge and discharge
solenoid valves 8-1 and 8-2
for adjusting the required
pressure.
At starting of sampling, the
valve 5-6 is opened for the
controller to check that a
pressure is recovered at the
transportation containers
outlet thus the container
valves have been opened by
the operator before of remounting.
OPTA-PERIPH
18
LNG SAMPLING SYSTEM
DATE
14/08/2008
REV.
0
6.
CHARGE TRANSPORTATION CONTAINERS:
Charge aggregate sampling containers
are provided with automatic/manual
interchange sequential control system as
well as time programmed automatically
purging and filling for complete unloading
sampling.
. The grab procedure is automated by
the Plant PC controller.
The accumulated average sample gas
of charge unloading is transferred from
holder cylinder to portable sampling
container and the gas will be controlled
in constant pressure of 4 bar-g at final
charging..
-Procedure for purging will be as per the fill and empty method refer
to Annex D of ISO 10715 and Appendix C of ISO 8943-2007 defined
according to the final pressure in cylinder : i.e: 8 cycles
(programmable) at 4 Kg/cm2g.
The procedure is operated within the following steps:
At the end of tansfert sampling - depending of cargo size programmeda couple of new spot cylinder will be fed in parallel by the holder cylinder
after a preliminary purge following procedure:
THI
- Open the vent valve and purge slowly the vent line :2 SL
- Open the load valve and purge the line and charge container: 5
SL
- Close the discharge valve and load the spot container at
4.Kg/cm2g
- Close the charge valve and vent the spot container until it reaches
atmospheric pressure
- Close the discharge valve and open the load the spot container at
4.Kg/cm2g
- Repeat the operation for a total of 8 cycles
- Load the spot container at 4 Kg/cm2g and close the discharge
and the charge valves
- Purge the holder cylinder through the vent valve
-
OPTA-PERIPH
19
LNG SAMPLING SYSTEM
DATE
14/08/2008
REV.
0
The two charge containers are rack mounted inside of an heated
casing at the back of holder cylinder cabinet temperature controlled at
approx. 40°C..
Portable gas sample containers are designed as a cylinder made of
stainless steel tubing and fitted with a stainless steel needle valve on
each end.
Pressure rating and capacity values:
Volume
0.5 Liters/each
Loading Press. 4.0 barg
Maximum Press 30.0barg
Design, manufacturing and verification of portable cylinder comply
with the European Pressure Equipment Directive PED 97/23/CE.
THI
7.
SYSTEM INTEGRATION:
The autosampling system is integrated in a SS cabinet ground mounted with all
components accessibility.
Electrical and pneumatic interconnections are supplied from the Control Cabinet
EExp mounted on right side and certified ATEX for zone 1 group B T3.
The control cabinet contents the Power distribution 220 VAC/ 24 VDC, the Solenoid
OPTA-PERIPH
20
LNG SAMPLING SYSTEM
DATE
14/08/2008
REV.
0
valve interface for processing the sampling valves with multiplexer unit and Modbus
controller, the holder cylinder level converter, the FIC 1 and /2 mass flow controllers
control board and the front screen system supervision.
The solenoid valves manifold , Multiplexer
I/O and Modbus communication interface
are integrated in the Burkert/Wago
modular system.
This system simplifies wiring distribution
and accepts additional elements to be
integrated later on.
A RS485 isolated interface is provided for
long distance communication through the
Modbus coupler to control room Application
PC Controller with the functionality of a
PLC.
The active communication channel works
independently of the solenoid valves
manifold controller for full duplex operation
over 19200 baud.
Control cabinet
A graphic screen is provided on the cabinet front door; the autosampler PID
represented gives the network configuration of system with actual parameters
collected from the Modbus hub. Two push button are provided for changing the
window or zooming the graphic display.
Graphic display zooming
THI
Solenoid manifold /
Multiplexer / Modbus coupler
OPTA-PERIPH
21
LNG SAMPLING SYSTEM
DATE
14/08/2008
REV.
0
8.
SYSTEM OPERATION DATA'S
System operation :
-At origin START of transfer is switched by operator and the sampling
starts automatically when the stable nominal flow rate through import
pipe-line is monitored by the system. The sampling will be temporary
suspended for any sudden change in the flow rate.
As well, the cargo size is programmed by operator on Application PC
Controller for calculation of sampling periods.
-Charge Holder cylinder empty detection is sensed for filling
authorisation and motive air pressure is switched during 30 sec. on
holder cylinder before original purging is made through the piston
shaft bore .
- According to cargo size filling cycle is switched during 6 to 12 H in
charge holder. During this cycle the air loading pressure is controlled
to 1.5 kg/cm2g in holder cylinder if process pressure is above 2.5
barg, if this pressure drops the air loading pressure is controlled at
process pressure less 1bar
.
-At the end of the charge holder cycle (6 to 12 H), if the level of
sample recovered in the Holder cylinder is corresponding to 40.5 SL
of gas +/- 10%, the sample is transferred to the charge
transportation containers within the procedure and if this operation is
proceeded without pressure alarm detection on charge and discharge
Pressure transmitter PT5 & PT3 , the information “Cylinder N°1/2
ready” is displayed; the Holder cylinder is switched –off with the
piston on down position and the system is isolated from process .
THI
The operator must proceed with collection of the charge
transportation containers.
Further to containers changing the system is automatically checking
at new transfer start-up by measuring gas pressure at PT5 & PT3
that containers have been mounted with valves opened. If case of
unsuccessful validation the system is hold in standby even if a new
Start of transfer is switched
Or
- If “Sampling standby” is automatically switched by the process flowrate dropping or manually switched by operator the system is hold in
standby with alarm “Sampling standby” displayed until nominal flowrate is recovered of Start transfer is switched
Or
-If “Sampling cancellation” is manually switched by operator: Holder
cylinder is vented up to empty detection and system is hold in
standby with alarm “Sampling cancellation” displayed until Start
transfer is switched
Or :
- If the holder cylinder high volume of 40.5 SL of gas + 10%
OPTA-PERIPH
22
LNG SAMPLING SYSTEM
DATE
14/08/2008
REV.
0
level alarm detects before end of sampling period, sample is
transferred to relative portable container and the high level sampling
alarm is displayed.
Or :
- If the sampling time is exceeded before the low volume of 40.5 SL
of gas - 10% is found: sample is transferred to relative portable
containers and the low level sampling alarm is displayed
Or :
- If the 4 Kg/cm2g pressure charge of portable container is not
sensed at PT5 during Holder to portable container transfer: Sampling
fault alarm is displayed and system is hold in standby .
Or
If the drop to BOG pressure (250 g/cm2g ) at portable container outlet
is not sensed at the discharge pressure transmitter PT3 during Holder
to Spot cylinder transfer : Sampling fault alarm is displayed and system
is hold in standby
9.
APPLICATION PC CONTROLLER:
DESCRIPTIVE
THI
Supplied for installation in safe area (Control Room) with the
communication architecture described on para 2 or for a local
installation in explosive area zone , the Application PC Controller is
processing the Sample take-off line data's acquisition, the spot
autosampling system, controlling the Gas Chromatograph results
statistical treatmen and the analyse of parameters influence.
Software development is in the OPTA-PERIPH scope with calibration
parameters as well as communication data-link to the control cabinet
EExp multiplexer and to the Gas Chromatograph.
Architecture is designed around PC hardware and Windows™
operating system : sampling processing and analysis method tables
are easily changed modified or edited in the same operating format.
OPTA-PERIPH
23
LNG SAMPLING SYSTEM
DATE
14/08/2008
REV.
0
FUNCTIONS:
PROBE VAPORIZER SUPERVISION
The graphic screen copies are representing some
steps of program for
PROBE VAPORIZER SUPERVISION
SPOT AUTOSAMPLER PROCESSING
CHROMATOGRAPH RESULTS STATISTICAL
TREATMENT / TRANSFER DATA-LOGGING
CHARGE AUTOSAMPLER PROCESSING
HOLDER FILLING
PURGING HOLDER
LINE PURGING
THI
STABILIZATION
OPTA-PERIPH
24
LNG SAMPLING SYSTEM
DATE
21/07/2007
REV.
0
FILLING BOMB
FLUSH BOMB
PURGING BOMB
FILLING ALL BOMBS
EMPTYING HOLDER
THI
END OF CYCLE
OPTA-PERIPH
25
LNG SAMPLING SYSTEM
DATE
21/07/2007
REV.
0
CHROMATOGRAPH RESULTS STATISTICAL TREATMENT:
THI
TRANSFER DATA LOGGING:
OPTA-PERIPH
26
LNG SAMPLING SYSTEM
DATE
21/07/2007
REV.
0