157883-000-CG-VT-0001
E&C Cryogenics Standard Plants Nitrogen Generation Unit (APSA L1) Training documentation
Peru LNG
E&C Cryogenics Standard Plants
- 4, rue des fusillés 94781 Vitry Sur Seine France Tel: + 33 (1) 45 73 66 66 - Fax : + 33 (1) 46 80 44 40
Author : ALSPE/CoH Revision: 0- 02-2009
Taining - PERU LNG Nitrogen Generation Unit
Generic part st
1 Day Welcoming introduction Process introduction Summary and training program philosophy Nitrogen Generation Unit systemic presentation PFD & PID Compression module Purification module sd
2 Day Heat Exchange module Distillation module Cold Production module Mass balance Safety : CnHm risks, safely operation
Operation training 3rd Day Process control – overview Start-up and shutdowns Deriming / Drying & exceptional regeneration Main control loops Alarms and trips Operating manual R01/R02 timing Supervision in steady conditions Trouble shooting quiz Operators questions and answers Training evaluation by participants Conclusions
CGG 09_018 dt 10th of april 2009
PRESENTATION
PERU LNG 2009
1
1. Generalities
1.1. Nitrogen On-Site Supply System N2 purity 100%
APSA Small Cryo. Cryo.
Bulk Supply
APSA L APSA LE Large Cryo. Cryo. High Purity LIN
99.9%
SPI
AMSA
Small Membranes
Large Membranes
95% 10 100
1000
10000
N2 Production (Nm3/h)
PERU LNG 2009
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1. Generalities
1.2. APSA L /LE : Process and Markets
APSAAPSA-L
« Classic » 7-10 barA N2
Chemicals Refineries Glass
APSAAPSA-LC
Claude Cycle 2-3 barA N2
Glass
APSAAPSA-LE
Booster Re-cycle Ultra High Purity
Electronics
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1. Generalities
1.3. Air Separation Unit (ASU) Inlet & Outlet
SOURCE : Atmospheric Air
Air Separation Unit
PRODUCTS: O2, N2, Ar (gas or liquid)
WASTE NITROGEN
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1. Generalities
1.4. Raw material composition ELEMENTS
SYMBOL
OXYGEN NITROGEN ARGON HELIUM NEON KRYPTON XENON HYDROGEN STEAM CARBON DIOXIDE
O2 N2 Ar He Ne Kr Xe H2 H 2O CO2 CH4 C 2+
HYDROCARBONS
{
COMPOSITION IN VOLUME 20,9 78,1 0,93 5,24 18,18 1,139 0,086 0,5
% % % ppm ppm ppm ppm ppm
Principal
Rare gas
variable 300 à 700 ppm 3 à 5 ppm < 0.5 ppm
Impurities
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1. Generalities
1.5. Cryogenic production stages ?
COLD PRODUCTION HEAT EXCHANGE
PURIFICATION
COMPRESSION
DISTILLATION
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1. Generalities
1.6. Cryogenic production modular approach GASEOUS PRODUCTS
COLD PRODUCTION
Residual Gas HEAT EXCHANGE
Air PURIFICATION
COMPRESSION
DISTILLATION LIQUID PRODUCTS
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1. Generalities
1.7. Plant’s Modules Overview DISTILLATION
PURIFICATION
COMPRESSION
HEAT EXCHANGE
COLD PRODUCTION
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1. Generalities
1.8. APSA L : Global Scheme
Residual Gas
AIR
APSA L LIN GAN
• Nitrogen recovery ≈ 40%
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1. Generalities
1.9. APSA L : Process Cycle Gaseous N2 to customer
Residual Enriched Gas (>35% O2)
R01
Liquid N2 to backup
R02 D01
Air inlet
K01
C01
Compression Purification Power
Cooling Water
Cold Production
Heat Exchange
Distillation
Civil Works PERU LNG 2009
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AIR PURIFICATION
PERU LNG - 2009
1
Air Purification
OBJECTIVES OBJECTIVES
TO TO REMOVE REMOVE THE THE VARIOUS VARIOUS AIR AIR CONTAMINANTS CONTAMINANTS IN IN ORDER ORDER TO TO PREVENT PREVENT TROUBLES TROUBLES IN IN APSA APSA UNITS: UNITS:
TEMPERATURE ~ -180°C
WATER WATER(air (airmoisture) moisture) Carbon CarbonDioxide DioxideCO2 CO2 Hydrocarbons HydrocarbonsCnHm CnHm Nitrous Nitrousoxide oxide(N2O) (N2O)
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Air Purification
WATER CO2 CnHm N2O
Purification Purification requirements requirements
-- unit unit corrosion corrosion -- plugging plugging (pipes, (pipes, exchangers, exchangers, column) column) by by solidification solidification due due to to cryogenic cryogenic temperature temperature (0°C (0°C // ice) ice)
-- plugging plugging (pipes, (pipes, exchangers, exchangers, column) column) by by solidification solidification due due to to cryogenic cryogenic temperature temperature (-130°C (-130°C // solid solid CO2) CO2)
- explosion explosion risk risk in in the the vaporizers vaporizers with with oxygen oxygen enriched enriched atmosphere atmosphere (Rich (Rich Liquid, Liquid, Oxygen) Oxygen)
- explosion explosion risk risk with with CnHm CnHm
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Air Purification Air Air Composition Composition // Air Air Contaminants Contaminants Air Composition
Inlet Comp. Normal
N2 O2 Ar
Nitrogen Oxygen Argon
78.11 % 20.96 % 0.93 %
H2 O CO2 CnHm
Water Carbon Dioxide Hydrocarbons
saturation 350 à 450 ppm Σ < 0.1 ppm
Ne He CH4 Kr H2 Xe
Neon Helium Methane Krypton Hydrogen Xenon
18 ppm 5.2 ppm 1 à 6 ppm 1.139 ppm 0.5 ppm 0.086 ppm
Inlet Comp. Peak
Purif. Outlet Max allowab
600 ppm 0.5 ppm
0.1 ppm
15 ppm
8 ppm
+ other natural or industrial impurities : hydrocarbons,CO, H2S, NO2 ..... PERU LNG - 2009
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Air Purification
Process Process presentation presentation
Contaminant-free Air OBJECTIVES: OBJECTIVES: •• ELIMINATION ELIMINATION OF OF WATER WATER IN IN VAPOUR VAPOUR FORM FORM •• ELIMINATION ELIMINATION OF OF CARBON CARBON DIOXIDE DIOXIDE CO2 CO2 MOLECULAR SIEVE: CO2, CnHm
•• ELIMINATION ELIMINATION OF OF HYDROCARBONS HYDROCARBONS EXCEPT EXCEPT
METHANE METHANE CH4 CH4 and and some some other other CnHm CnHm
ALUMINA: WATER
Air Airpasses passesthrough throughupward upwardaavessel vessel equipped with two specific materials: equipped with two specific materials: - -ALUMINA: ALUMINA:to totrap trapwater watermolecules molecules Air with contaminants: H2O, CO2, CnHm
- -MOLECULAR MOLECULARSIEVE: SIEVE:to totrap trapCO2 CO2and and Hydrocarbon molecules Hydrocarbon molecules
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Air Purification
Adsorption Adsorption Process Process
ATTRACTION Molecules
Pores DIFFUSION/ FIXATION
Adsorbent
ALUMINA ALUMINA and and MOLECULAR MOLECULAR SIEVE SIEVE are are solid solid materials materials in in the the form form of of porous porous particles particles of of 22 to to 55 mm mm diameter: diameter: they they are are called called ADSORBENTS. ADSORBENTS.
The The ADSORPTION ADSORPTION process process occurs occurs in in 22 steps: steps: -- first, first, an an attraction attraction of of the the molecules molecules to to the the adsorbent adsorbent -- then, then, aa diffusion diffusion of of the the molecules molecules into into the the pores pores where where they they are are fixed fixed (or (or trapped). trapped).
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Air Purification
Adsorption Adsorption Process Process
Reversible Process : Adsorption & Desorption Adsorption Adsorption increases increases (the (the amount amount of of adsorbed adsorbed molecules molecules increases) increases) when: when: the the pressure pressure increases increases the the temperature temperature decreases decreases
Gaseous phase
Adsorbed phase
Solid
ADSORPTION ADSORPTION IS IS A A REVERSIBLE REVERSIBLE PROCESS: PROCESS: ifif the the pressure pressure decreases decreases or or ifif the the temperature temperature increases, increases, the the adsorbed adsorbed molecules molecules will will be be able able to to leave leave the the pores pores of of the the adsorbent adsorbent particles: particles: this this is is the the Desorption Desorption of of the the adsorbent. adsorbent. (also Regeneration)) (also called called Regeneration Thus, fixed adsorbent adsorbent quantity, quantity, we we design design aa cyclic cyclic process process Thus, for for aa fixed with with alternating alternating phases: phases: adsorption/desorption. adsorption/desorption. ¾we ¾we can can play play with with the the temperature: temperature: TSA TSA cycle cycle (Temperature (Temperature Swing Swing Adsorption) Adsorption) ¾we ¾we can can play play with with the the pressure: pressure: PSA PSA cycle cycle (Pressure (Pressure Swing Swing Adsorption). Adsorption). PERU LNG - 2009
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Air Purification
Adsorbent Adsorbent characteristics characteristics
• The name of Adsorbents designates porous solid materials. • Their main characteristic is a maximum surface (active zone for the adsorption process) in a small volume: we define the specific area. • Adsorbents come in different forms: - spherical balls - cylindrical pellets - irregular crushed particles
ACTIVATED CARBON ALUMINA MOLECULAR SIEVE: Type A, Type X
Each gram of product particle has a surface equivalent to a tennis court Chimical formula
Specific area m2/g
Pore diameter Angström (10-10 m)
C
800 to 1500
40 to 5000
AL2O3
300 to 350
10 to 40
SiO2, Na2O CaO, K2O
900
3 to 10
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Air Purification
Selectivity Selectivity of of the the process process
Affinity (Adsorbent / Molecule) depends on : •• The The type type of of adsorbent: adsorbent: –– presence presence of of attraction attraction field field –– diameter diameter of of the the pores pores •• The The type type of of molecule: molecule: –– their their physical physical and and chemical chemical characteristics characteristics determine determine the the intensity intensity of of the the adsorbent adsorbent attraction: attraction: so, so, we we designate designate molecules molecules strongly strongly attracted attracted (with (with electrical electrical moment) moment) and and molecules molecules weakly weakly attracted attracted (neutral (neutral molecules) molecules) –– the the size size of of the the molecules molecules must must be be smaller smaller than than the the diameter diameter of of the the pores: pores: thus, thus, nitrogen nitrogen molecule molecule is is able able to to pass pass into into aa 44 Å Å pore, pore, but but not not into into aa 33 Å Å pore. pore. Adsorbed molecules ACTIVATED CARBON ALUMINA MOLECULAR SIEVE
Oil vapour: Hydrocarbons C2 and C3 types H2O C2H2, NO2, CO2, H20
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Air Purification
Choice Choice of of adsorbents adsorbents
The function of the adsorption process for an APSA unit is to trap in vapour form the air contaminants such as water, carbon dioxide CO2 and hydrocarbons, before feeding the cold box. To trap water, knowing that air is always saturated after compression process, the choice indifferently could be molecular sieve or alumina. We prefer alumina for the following reasons: - alumina is less sensitive to the possible presence of liquid water particles - the temperature of regeneration process for alumina is colder: around 40°C for alumina, 250°C for molecular sieve
ALUMINA ALUMINA HH2OO 2
To trap CO2, the only choice is molecular sieve. The same for hydrocarbons, mainly made up of acetylene C2H2: it is not possible to trap methane CH4 by the adsorption process.
MOLECULAR MOLECULAR SIEVE SIEVE CO CO22,,CC22HH22
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Air Purification
Adsorption: Adsorption: Water Water analogy analogy
Saturated Gas
ADSORPTION Dry gas
Saturated zone
front
Clean zone
DESORPTION (REGENERATION) Saturated Gas
Dry gas
END OF DESORPTION (REGENERATION)
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Air Purification
Installation Installation design design
The The design design of of the the installation installation is is aa combination combination with with two two types types of of adsorbents: adsorbents: •• first, first, compressed compressed air air passes passes through through aa bed bed of of alumina alumina in in order order to to trap trap water water •• then, then, compressed compressed air air passes passes through through aa bed bed of of molecular molecular sieve sieve intended intended to to trap trap CO and Hydrocarbons CO22 and Hydrocarbons Thus, Thus, we we keep keep molecular molecular sieve sieve free free of of moisture moisture contamination. contamination.
MOLECULAR SIEVE CO2, C2H2
MOLECULAR SIEVE
Adsorber V-6701 A/B
ALUMINA
ALUMINA H 2O
AIR
AIR PERU LNG - 2009
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Air Purification Adsorption Adsorption // Regeneration Regeneration Cycle Cycle Using Using aa fixed fixed amount amount of of adsorbent, adsorbent, we we know know that that the the duration duration of of adsorption adsorption process process will will be be limited: limited: after after aa certain certain duration duration of of air air circulation, circulation, the the pores pores of of the the adsorbent adsorbent become become saturated: saturated: -- with with water water molecules molecules for for alumina alumina -- with and Hydrocarbon Hydrocarbon molecules molecules for for molecular molecular sieve sieve with CO CO22 and
We We obtain obtain the the saturation saturation of of the the adsorbents: adsorbents: the the adsorption adsorption process process is is over. over. Contaminant-free air
To To achieve achieve aa continuous continuous air air purification purification compatible compatible with with the the non-stop non-stop distillation distillation process process of of APSA APSA unit, unit, we we need need an an operating operating cycle cycle with with two two adsorbers. adsorbers.
Air with contaminants
REGENERATION ADSORPTION
An An arrangement arrangement with with two two adsorbers adsorbers in in parallel parallel allows allows to to purify purify compressed compressed air air with with one one adsorber adsorber (ADSORPTION (ADSORPTION phase), phase), while while the the second second one one is is in in desorption process (REGENERATION phase). desorption process (REGENERATION phase). When When the the first first adsorber adsorber is is close close to to the the limit limit of of adsorption adsorption capacity, capacity, we we perform perform aa reverse reverse operation operation in in order order to to feed feed with with compressed compressed air air the the second second adsorber, adsorber, which which is is contaminant-free contaminant-free thanks thanks to the previous regeneration process. to the previous regeneration process. PERU LNG - 2009
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Air Purification
Adsorption Adsorption front front in in the the bed bed
Bed Height
Contaminant-free air
t = 100 min
Adsorbed quantity
t = 20 min 0 500
400
300
200
100
CO2 (ppm)
0
0
1
2
3
4
5
Adsorbed quantity
Air with contaminants
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Air Purification Regeneration Regeneration front front in in the the bed bed Regeneration fluid : Vaporized Rich Liquid (VRL)
Bed Height
Vaporized Rich Liquid
Desorbed quantity
0 500
400
300
200
100
CO2 (ppm)
0
0
1
2
3
4
5
Desorbed quantity
Saturated Vaporized Rich Liquid PERU LNG - 2009
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Air Purification Adsorption Adsorption // Regeneration Regeneration Cycle Cycle Influence of pressure and temperature
Adsorbed quantity
T1 1 Pressure effect (depressurization) 2 Temperature effect (heating)
T2 > T1
3
Partial pressure
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Air Purification Air
Vaporized Rich Liquid
Technology Technology Regeneration Regeneration fluid fluid :: Vaporized Vaporized Rich Rich Liquid Liquid (VRL) (VRL)
Horizontal Horizontal beds beds
Adsorption Adsorption phase phase :: ¾ ¾ Cycle Cycle time time :: 150 150 min min ¾ ¾ Air Air pressure pressure :: 8.1 8.1 bar bar gg ¾ ¾ Air Air temperature temperature :: 40°C 40°C Regeneration Regeneration phase phase :: ¾ ¾ Regeneration Regeneration temperature temperature :: 90°C 90°C (heater (heater outlet) outlet) ¾ ¾ Air Air pressure pressure :: 0.1 0.1 bar bar gg ¾ ¾ Heating Heating duration duration :: ~20 ~20 min min ¾ ¾ Cooling Cooling duration duration :: ~100 ~100 min min
Mole Sieve bed Alumina bed
Air
Vaporized Rich Liquid
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Air Purification
V01 V01 // V02 V02 Installation Installation Electric heater EH-6701
Air to Cold Box
VRL CVWO009A
CVWO009B
CVAG06A
CVAG06B
KV 530
Regeneration Phase
V-6701 A
Event VRL
V-6701 Adsorption Phase B
KV 515
KV 525
KV 516
KV 526
KV 510
KV 520
Air PERU LNG - 2009
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Air Purification
Purification Purification cycle cycle
Air
Purification steps
È HP Isolation È Depressurization È Blow-Off Bottle in Regeneration phase
VRL VRL
Bottle in Adsorption phase
È Heating È Cooling È LP Isolation È Pressurization È Parallel position
Air
È Adsorption
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Air Purification
Pressure Pressure cycle cycle
Air Bottle 1
Regeneration Heating
pressure
Adsorption
VRL VRL
Bottle in Adsorption phase
time
Bottle 2 Regeneration Heating
Cooling
Adsorption
pressure
Bottle in Regeneration phase
Cooling
time
Air
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Air Purification
VRL
Automatic Automatic sequence sequence
Cold Box
V6701 A
Event
V6701 B
Air
On line V6701 B HP Isolation V6701 A
VRL
V6701 A
Cold Box
Event
V6701 B
Air
Depressurization V6701 A
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Air Purification
VRL
Automatic Automatic sequence sequence
Cold Box
V6701 A
Event
V6701 B
Air
Blow-Off V6701 A
VRL
Cold Box
V6701 A
Event
V6701 B
Air
Heating V6701 A
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Air Purification
VRL
Automatic Automatic sequence sequence
Cold Box
V6701 A
Event
V6701 B
Air
Cooling V6701 A
VRL
Cold Box
V6701 A
Event
V6701 B
Air
LP Isolation V6701 A
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Air Purification
VRL
V6701 A
Automatic Automatic sequence sequence
Cold Box
Event
V6701 B
Air
Pressurization V6701 A
VRL
Cold Box
V6701 A
Event
V6701 B
Air
Parallel Position
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Air Purification
Temperature
Temperature Temperature profile profile
Inlet temperature
Heating temperature
Good Regeneration indicator
Outlet temperature Cold Desorption
Hot Desorption Heat Peak
VRL temperature at cold box outlet
Heating
Cooling
Time
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Air Purification What does the purification process look like ?
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Air Purification What does the purification process look like ?
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EXCHANGERS
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4. Heat Exchange
4.1. Why exchange the heat ? Gaseous N2 to customer
Residual Enriched Gas (>35% O2)
R01
Liquid N2 to backup
R02 D01
Air inlet
K01
C01
Compression Purification
NON-CRYOGENIC
Cold Production
Heat Exchange
Distillation
CRYOGENIC PERU LNG - 2009
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4. Heat Exchange
4.2. Principles of Heat Exchange
GOAL
DTo get air at good conditions for the distillation DTo warm up gaseous product from the cryogenic temperature to the ambient one
PRINCIPLES
DHeat flux from the Hot fluid to cold fluid DDriving force = temperature difference DCounter flow arrangement DHeat exchange in an aluminium brazed Heat Exchanger
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4. Heat Exchange
4.3. Heat exchange formula
ΔH = K . S . Ln(ΔT) where
ΔH = Duty or Heat exchanged (kcal/h) K = Heat exchange coeff = f(fluids, material, flow) (kcal/h.m2.°C) S = Surface (m2) ΔT = Average temperature difference between hot and cold fluids (°C)
PERU LNG - 2009
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4. Heat Exchange
4.4. Heat exchange formula
ΔH = Q . Cp . ΔT where
ΔH = Duty or Heat exchanged (kcal/h) Q = Flowrate (Nm3/h) Cp = Specific heat (kcal/Nm3/°C) ΔT = Temperature difference for the same fluid (°C)
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4. Heat Exchange
4.5.Three types of heat exchanger
+
+
Counter-current
+
+
Co-current
+
+
Cross current
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4. Heat Exchange
4.6. Co-current exchanger Insulation
Cold Nitrogen Hot Nitrogen Cold Nitrogen
-100°C
-50°C
0°C
-50°C
-100°C
-50°C
Same number of hot passages and cold passages Temperature of Hot Nitrogen at the end of the exchanger ? PERU LNG - 2009
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4. Heat Exchange
4.7. Counter-current exchanger
Hot Nitrogen
-5°C
-10°C
-100°C
0°C
-5°C
-95°C
-5°C
-10°C
-100°C
Cold Nitrogen
Cold Nitrogen
Same number of hot passages and cold passages Temperature of Hot Nitrogen at the end of the exchanger ? PERU LNG - 2009
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4. Heat Exchange
4.8. ΔT Warm End definition Air
WN2
ΔT warm end
GAN
ΔT cold
Brazed aluminium HX ΔT cold = 0°C ΔT warm end ~ 2°C
Loss of cold capacity to be produced by the turbine
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4. Heat Exchange
4.9. Basis about heat exchange diagram
-100
-95
si te
-100°C
0°C
-45°C
-95°C
-5°C
-50°C
-100°C
N2
N2
po
ΔT Warm End ?
co m
d l Co
m o c
po
te i s
-50°C
Ho t
Exchanged heat (kcal/h)
Air
-5°C
-5
0
Temperature (°C) PERU LNG - 2009
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4. Heat Exchange
4.10. Real heat balance diagram for APSA L ΔH Heat flow (kcal/h) 1400000
1200000
Hot composite 1000000
Cold composite
800000 600000
400000
200000
0 -200
-150
-100
-50
0
50
Temperature (°C) PERU LNG - 2009
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4. Heat Exchange
4.11. Heat balance QC T4
T1
Warm end
Cold end
T3
QF
Heat Balance :
T2
T4 T1
ΔH
T3
T
T2
ΔH = Q . Cp . ΔT ΔH = ΔHC = QC . CpC . ( T2 – T1 ) = - ΔHF = - QF . CpF . ( T4 – T3 ) PERU LNG - 2009
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4. Heat Exchange
4.12. Heat exchange exercise Warm end
We
consider a counter flow exchanger
8 Nm3/h 20°C
25°C
want to warm up 5 Nm3/h of N2 from - 100 to 20°C at 1 bar abs
We
8 Nm3/h flowrate of Air is available at 25°C and 5 bar abs
AIR
NITROGEN
A
Cp(Air) Cp(N2)
-100°C 5
Nm3/h
T=?
= 0.31 kcal/Nm3/°C
= 0.31 kcal/Nm3/°C
Air temperature at cold end ?
Cold end PERU LNG - 2009
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4. Heat Exchange
4.13. Heat exchange exercise result Warm end 8 Nm3/h 20°C
25°C
Heat exchanged by Nitrogen ΔHN = 5x0.31x[20-(-100)] = 186 kcal/h
AIR
NITROGEN
2
-100°C
Heat exchanged by air ΔHAIR = 8x0.31x[T-25]
But ΔHN = - ΔHAIR = 186 kcal/h
Then 8x0.31x[T-25] = -186 kcal/h
Finally T = -186/(8x0.31)+25 = -50°C
2
T= -50°C
5 Nm3/h Cold end PERU LNG - 2009
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4. Heat Exchange
4.14. Influence of flowrate on heat exchange
Flow evolution
ΔT warm end
ΔT cold end
Hot fluid
Cold fluid
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4. Heat Exchange
4.15. Influence of temperature on heat exchange
Temperature
ΔT warm end
ΔT cold end
Hot fluid
Cold fluid
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4. Heat Exchange
4.16. Counter flow arrangement
Perforated fins
Heringbone fins
Spacer bar Parting sheet
Exchange fin
Spacer bar
Serrated fins
Flowrate Parting sheet PERU LNG - 2009
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4. Heat Exchange
4.17. Different flow arrangements
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4. Heat Exchange
4.18. Different type of distributors
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4. Heat Exchange
4.19. Different type of fins
Straight fins
Serrated fins
Perforated fins
Heringbone fins PERU LNG - 2009
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4. Heat Exchange
4.20. General view of the heat exchanger
1
8 7
4 3
10 6
11 9
12
14
1 3 15
5 2
1
- Assembly
6
- Width
10
- Side plate
2
- Outlet fluid
7
- Stack
11
- Parting sheet
3
- Core
8
- Length
12
- Heat transfer fins
4
- Header
9
- Passes
13
- Distributor fins
5
- Nozzle
14
- Spacer bar
15
- End bar PERU LNG - 2009
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4. Heat Exchange
4.21. General view of the heat exchanger
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4. Heat Exchange
4.22. Warm end Embrittlement hazard
Nitrogen piping at warm end of the Heat Exchanger is not designed for cryogenic temperature
Occasionally, there can be cold fluid ingress at the warm end : DDuring process deviation DDuring stop of the plant
Precautions must be taken to prevent cold embrittlement
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COLD PRODUCTION
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6. Cold Production
6.1. Energy balance principle
Σheat (inlet ) = Σheat (outlet )
Heat inlet or Cold losses
APSA-L
Heat losses or Cold inlet
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6. Energy Balance & Cold Production
6.2. Cold balance application Warm end ΔT
0.1 bar g 35°C
7 bar g -171°C GAN
LIN
Liquid production
ΔΤ{
R01
R02
Insulation losses
D01
Air inlet
K01
C01
Turbine work 8 bar g 40°C PERU LNG – 2009
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6. Cold Production
6.3. Energy balance
Cold losses or heat inlets
DHeat exchanger warm end temperature difference DLiquid production DHeat entrance due to non perfect insulation
Cold inlets or heat losses
DTurbine work DIsotherm expansion of products DLiquid assist
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6. Cold Production
6.4. Cold balance comparison
Small units GAS
LIQUID
Large plants GAS
LIQUID
Insulation
70%
7%
20%
1%
Warm end ΔT
30%
2%
80%
3%
0%
91%
0%
96%
Liquid production
PERU LNG – 2009
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6. Cold Production
6.5. Why a Cold Production is required ?
AIM
DSTART-UP: COOL DOWN To ensure a decrease of the temperature in the cold box DNORMAL RUN: ENERGY BALANCE To maintain the cold balance of the plant
HOW
DBy withdrawing some heat out of the cryogenic system DBy expansion of air
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6. Cold Production
6.6. Turbine principle Symmetric Symmetricwork workto tothe theone oneof ofaacentrifugal centrifugalcompressor compressor
Compresseur
Turbine
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6. Cold Production
6.7. Turbine thermo-dynamical Principle
Theorem of Bernoulli :
P V² + − E = cste ρ 2
Static pressure Compressor / Pump
Dynamic pressure Turbine
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6. Cold Production
6.8. Turbine thermodynamical Principle
Increase in the gas’ speed without energy extraction in the inlet vanes (1) ⇒ static pressure diminishes
2 1
3
Decrease in the gas’ speed with energy extraction in the relaxation wheel (2) ⇒ dynamic pressure diminishes Decrease in the gas’ speed without energy extraction in the diffuser (3) ⇒ dynamic pressure is transformed into static pressure PERU LNG – 2009
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6. Cold Production
6.9. Turbine overview
Entrance gas process
Outing g as
process
Turbine body
PERU LNG – 2009
10
6. Cold Production
6.10. Turbine wheels Gas outing
Gas entrance
PERU LNG – 2009
11
6. Cold Production
6.11. Turbine wheels
Wheel of the turbine
Discharge
Adjustable diffuser (IGV)
Arrival of the fluid by the volute
PERU LNG – 2009
12
6. Cold Production
6.11. Speed triangle Fixed part : Distributor 0
r U1
r W1
1
r r U r V2 2 W2
0
r V1
1 2 3
2
Mobile guide vanes ⇒ Wheel
PERU LNG – 2009
13
6. Cold Production
6.12. How braking cryogenic turbines ? Production of mechanical energy with the expansion wheel
Energetic stability ⇒ Consumption of this energy
Braking of the turbine
Electrical generator
Oil spin-dry pump
Oil brake
Air brake
Booster brake
PERU LNG – 2009
14
6. Cold Production
6.13. APSA-L Oil brake turbine principle
Oiled contact surface
Turbine wheel - Figure of an oil brake PERU LNG – 2009
15
6. Cold Production
6.14. APSA-L cold production equipment
Air Water Air
Oil Tank
PERU LNG – 2009
16
6. Cold Production
6.15. APSA-L PERU LNG : LIN Production Case
F = 1650 Nm3/h P = 4.3 bar g T = -148°C
LRV Turbine
F = 1650 Nm3/h P = 0.2 bar g T = -184°C
-19 kW
19 kW
S = 43000 rpm PERU LNG – 2009
17
6. Cold Production
6.16. Cryostar ECO turbine
Oil tank
Oil brake valve PERU LNG – 2009
18
6. Cold Production
6.17. Cryostar ECO turbine Oil pump
Oil tank
Oil cooler
PERU LNG – 2009
19
6. Cold Production
6.18. Turbine elements
Expander stage
Oil brake sleeve in bearing housing PERU LNG – 2009
20
6. Cold Production 6.19. Expansion turbine behaviour
2 choices to increase the cold production of the plant: Dincrease the turbine inlet pressure of 100 mbar Ddecrease the turbine outlet pressure of 100 mbar
What is the best choice ? EXPANSION POWER VARIATION VS P VARIATION EITHER ON MP SIDE OR BP SIDE 16.1 16
Conclusion
15.9
Be careful with the pressure on the BP side of the turbine. Quick loss of cold production
15.8 15.7 Power (kW)
15.6
POWER BP VAR (KW) POWER MP VAR (kW)
GAIN BP
15.5 15.4
GAIN MP
15.3 15.2 15.1 15 0
10
20
30
40
50
60
70
80
90
100
DP (mbar)
PERU LNG – 2009
21
6. Cold Production
6.20. P&ID : Expansion turbine
PERU LNG – 2009
22
AIR DISTILLATION PRINCIPLE
PERU LNG -2009
1
Distillation Goal and principle
GOAL
DTo separate Nitrogen and Oxygen from atmospheric Air
PRINCIPLE
DSeparation by Distillation : Content difference between liquid and vapour phases
KEY PARAMETERS
DBoiling Point DLiquid vapour equilibrium DFractional distillation DReflux
PERU LNG -2009
2
Distillation
PRINCIPLE PRINCIPLE
WATER + ALCOHOL MIXTURE: ALCOHOL: most volatil component WATER: least volatil component VAPOUR: enriched in most volatil component:
ALCOHOL
LIQUID: enriched in least volatil component:
LIQUID Mixture Two components:
WATER + ALCOHOL
BOILING APSA03/Distill1/VA#1
WATER PERU LNG -2009
3
Distillation
PRINCIPLE PRINCIPLE
AIR = MIXTURE NITROGEN (79 %) + OXYGEN (21 %) most volatil component : NITROGEN least volatil component : OXYGEN VAPOUR: enriched in most volatil component:
NITROGEN
LIQUID AIR -200°C, 1 b abs
LIQUID: enriched in least volatil component:
BOILING APSA03/Distill1/VA#2
OXYGEN PERU LNG -2009
4
Distillation
Boiling éfinition Boiling Point Point ddéfinition
At Atthe theboilling boillingpoint, point,there thereare aretwo twophases: phases: --aaboiling boilingLIQUID LIQUID --aarelease releaseof ofVAPOUR VAPOUR AAboiling boilingpoint pointis isdefined definedwith: with: --aaTEMPERATURE TEMPERATURE TT --aaPRESSURE PRESSURE PP
VAPOUR Thus Thuswe wedefine defineaa LIQUID-VAPOUR LIQUID-VAPOUREQUILIBRIUM EQUILIBRIUM
P, T LIQUID
PERU LNG -2009
5
Distillation
Boiling Boiling Points Points Boiling point values and volatility scale
Name
Symbol
Molecular Weight (g)
Boiling Temperature @ 1,013 bar abs.
Helium Hydrogen Neon Nitrogen Air Argon Oxygen Kripton Xenon
He H2 Ne N2 Air Ar O2 Kr Xe
2 2 20 28 29 40 32 84 131
-269 °C -253°C -246°C -196°C -191°C -186°C -183°C -153°C -108°C
PERU LNG -2009
6
Distillation
Boiling Boiling Points Points
At the boiling point, if one parameter changes (Pressure or Temperature), the other parameter has to change too:
NITROGEN VAPOUR
LIQUID
VAPOUR LIQUID
VAPOUR LIQUID
OXYGEN
1 b abs - 196 °C
VAPOUR
3.6 b abs - 183 °C
VAPOUR
11 b abs - 168 °C
LIQUID
LIQUID
VAPOUR
LIQUID
1 b abs - 183 °C
3.6 b abs - 168 °C
11 b abs - 152 °C PERU LNG -2009
7
Distillation
Boiling Boiling Points Points Curves Curves
PRESSURE AND TEMPERATURE RELATIONSHIP: •If the Pressure increases, the Temperature has to increase too OR •If the Temperature increases, the Pressure has to increase too AND inversely.
D’où les courbesthe des points d’ébullition: Consequence: boiling point curves 4
Pressure = f (Temperature)
P
Temperature = f (Pressure)
T
Liquid State
Gaseous State
Gaseous State
Liquid State
P
T
Curves: Liquid state and Gaseous state separation APSA03/Distill1/VA#6
PERU LNG -2009
8
Distillation
Boiling Boiling Points Points Nitrogen versus Oxygen 4.5 b abs
1.3 b abs
VAPOUR
VAPOUR
LIQUID
LIQUID
- 183 °C - 196 °C NITROGEN NITROGEN NITROGEN
OXYGEN
1 b abs ISOBARIC ISOBARIC
OXYGEN OXYGEN
- 180 °C ISOTHERMAL ISOTHERMAL Nitrogen Nitrogen is is more more volatil volatil than than Oxygen Oxygen:
-NITROGEN -NITROGEN == most volatile component -OXYGEN -OXYGEN == least volatile component PERU LNG -2009
9
Distillation
Nitrogen Nitrogen -- Oxygen Oxygen mixture mixture
For Foran anOXYGEN-NITROGEN OXYGEN-NITROGENMIXTURE MIXTUREat atthe theLIQUID-VAPOUR LIQUID-VAPOUR EQUILIBRIUM, EQUILIBRIUM,
NITROGEN NITROGENbeing beingthe themost mostvolatile volatilecomponent: component:
--the thevapour vapourphase phaseBECOMES BECOMESENRICHED ENRICHED IN INNITROGEN NITROGEN
- -the theliquid liquidphase phaseBECOMES BECOMESLESS LESS CONCENTRATED IN NITROGEN: CONCENTRATED IN NITROGEN:
P, T
O2+N2
O2+N2
CONSEQUENTLY, CONSEQUENTLY,IT ITBECOMES BECOMES ENRICHED IN OXYGEN ENRICHED IN OXYGEN
(the (theVapour Vapourphase phaseand andthe theLiquid Liquidphase phaseare arecalled calledCONCOMITANT CONCOMITANTPHASES) PHASES) PERU LNG -2009
10
Distillation
Fractional Fractional Distillation Distillation VAPOUR even more enriched in NITROGEN CONDENSER
VAPOUR: enriched in NITROGEN
2d BOILING LIQUID: enriched in OXYGEN
1st BOILING
Liquefaction: Liquid enriched in NITROGEN
PERU LNG -2009
11
Distillation
Fractional Fractional Distillation Distillation VAPOUR: "PURE" NITROGEN
Successive Boilings and Liquefactions
R
UR O P VA
R MO
LIQUID: "PURE" OXYGEN
MO D N A E
ITR N N DI E ICH R N EE
LIQ
EN G O
EN G XY O IN D HE ty) C I vi R a N r E E by g R MO own D N sd A w RE id flo O M iqu D l I ( U
APSA03/Distill1/VA#10
PERU LNG -2009
12
Distillation
Fractional Fractional Distillation Distillation
ISOBARIC ISOBARIC SYSTEM: SYSTEM: pressure pressure is is the the same same in in each each vessel vessel e.g.: e.g.: 11 b b abs abs
- 196 °C "PURE" NITROGEN
CONSEQUENCE: CONSEQUENCE: TEMPERATURE TEMPERATURE GRADIENT GRADIENT
- 183 °C "PURE" OXYGEN APSA03/Distill1/VA#11
PERU LNG -2009
13
Distillation
LIQUID LIQUID –– VAPOUR VAPOUR CONTACT CONTACT
SUPPRESSION OF THE BOILERS AND CONDENSERS Vapour: HOTTER
For that, we achieve a LIQUID-VAPOUR CONTACT: the Vapour passes through the Liquid in the vessel
Liquid: COLDER
- the vapour HOTTER, makes the liquid boiling - the liquid COLDER, condenses the vapour
LIQUID
Boiling of the LIQUID = VAPOUR
(colder)
LIQUID-VAPOUR Contact
Heat Transfer (calories)
LIQUID-VAPOUR CONTACT VAPOUR
Liquefaction of the VAPOUR = LIQUID
(hotter)
APSA03/Distill1/VA#12
PERU LNG -2009
14
Distillation
LIQUID LIQUID –– VAPOUR VAPOUR CONTACT CONTACT
SUPPRESSION OF THE BOILERS AND CONDENSERS
CONDENSER
We We only only need: need: •One •One boiler boiler at at the the bottom bottom •One •One condenser condenser at at the the top top
TE
T: N DIE A GR ter E t UR is ho lder T RA pour is co E MP Va id u Liq
BOILER PERU LNG -2009
15
Distillation Fractional Fractional Distillation Distillation :: Columns Columns CONDENSER
LIQUID BECOMES RICHER IN LEAST OLATILE COMPONENT
LIQUID-VAPOUR CONTACT CONTACT LIQUID-VAPOUR
LABORATORY LABORATORY Device Device
VAPOUR BECOMES RICHER IN MOST VOLATILE COMPONENT
MOST VOLATILE COMPONENT
DISTILLATION DISTILLATION COLUMNS: COLUMNS: TRAYS TRAYS PACKING PACKING
LEAST VOLATILE COMPONENT
BOILER: Vaporizer PERU LNG -2009
16
Distillation
Regular Regular Column Column
CONDENSER
Condenser LIN DRAW-OFF
GAN DRAW-OFF
Σ
GAN LIN
GOX DRAW-OFF
VAPOUR LIQUID = REFLUX
AIR FEED
PACKING SECTIONS
AIR
GOX
Σ
LOX DRAW-OFF VAPORIZER
Vaporizer LOX PERU LNG -2009
17
Distillation Volatility scale
He H2 Ne N2 Ar O2 Kr Xe CnHm
Air Air Components Components breakdown breakdown
NITROGEN HELIUM HYDROGEN NEON
AIR : NITROGEN OXYGEN ARGON HELIUM KRYPTON NEON XENON HYDROGEN CnHm
OXYGEN ARGON KRYPTON XENON CnHm
PERU LNG -2009
18
Distillation
From From the the regular regular column column to to the the APSA APSA
FOR A GAS NITROGEN PRODUCTION, ONLY THE UPPER SECTION OF THE COLUMN IS NECESSARY: we do not need the lower section CONDENSER
GAN DRAW-OFF
CONDENSER
VAPOUR
GAN DRAW-OFF
LIN DRAW-OFF
AIR FEED
LIQUID
AIR FEED
LIN DRAW-OFF
GOX DRAW-OFF LOX DRAW-OFF
VAPORIZER
PERU LNG -2009
19
Distillation
From From the the regular regular column column to to the the APSA APSA CONDENSER
GAN DRAW-OFF
EQUIPMENTS NEEDED: - PACKING SECTION - CONDENSER AT THE TOP - AIR FEED IN GASEOUS STATE
PACKING SECTION
- GAN DRAW-OFF - LIQUID WASTE OUTLET
AIR FEED
Air feed must be in gaseous state,
in order to build-up the up-coming vapour:
LIQUID WASTE OUTLET
so that, the vaporizer is no longer necessary PERU LNG -2009
20
Distillation
Material Material Balance Balance
INCOMING INCOMING MATERIAL MATERIAL QUANTITY= QUANTITY= OUTGOING OUTGOING MATERIAL MATERIAL QUANTITY QUANTITY
400 Nm3/h
THE THELIQUID LIQUIDWASTE WASTEIS ISTHE THE CONSEQUENCE OF THE MATERIAL CONSEQUENCE OF THE MATERIAL BALANCE: BALANCE: Flowrate, Flowrate,O2 O2content content ITS ITSO2 O2CONTENT CONTENTIS ISALWAYS ALWAYSHIGHER HIGHER THAN THE ONE OF AIR; THAN THE ONE OF AIR; For Forthat, that,this thisliquid liquidisiscalled: called:
1000 Nm3/h O2 = 21 %
RICH RICHLIQUID LIQUID
Flowrate = 1000 - 400 = 600 Nm3/h 1000 x 21 % O2 = = 35 % 600
PERU LNG -2009
21
Distillation VAPORIZATION VAPORIZATION vs vs LIQUEFACTION LIQUEFACTION • VAPORIZATION 1 kg Liquid
1 kg Vapour
heat quantity SUPPLY
• LIQUEFACTION
1 kg Liquid
1 kg Vapour
heat quantity DRAW-OFF
APSA03/Distill2/VA#4
PERU LNG -2009
22
Distillation LATENT LATENT HEAT HEAT OF OF VAPORIZATION VAPORIZATION DEFINITION: Heat quantity necessary to vaporize totally 1 kg of liquid
1 kg Vapour
1 kg Liquid
Heat quantity: kcal
OXYGEN: OXYGEN: 51 51kcal kcal(-183 (-183°C, °C,11bbabs) abs) NITROGEN: NITROGEN: 47.6 47.6kcal kcal(-196 (-196°C, °C,11bbabs) abs)
APSA03/Distill2/VA#5
PERU LNG -2009
23
Distillation
Vaporizer Vaporizer -- Condenser Condenser system system
• OBJECTIVES:
CONDENSER
To liquefy gas nitrogen at the top of the column in order to achieve the Reflux.
GAN
LIN
• PRINCIPLE: We need a specific device to draw-off the connecting heat quantity from gas nitrogen. Heat quantity DRAWN-OFF
GAN
LIN PERU LNG -2009
24
Distillation
Vaporizer Vaporizer -- Condenser Condenser system system
• PRINCIPLE: In In an an EXCHANGER, EXCHANGER, we we achieve achieve an an HEAT HEAT TRANSFER TRANSFER (CALORIES) (CALORIES) between between GAS GAS NITROGEN NITROGEN and and RICH RICH LIQUID LIQUID CONSEQUENCES: CONSEQUENCES: -- Gas Gas Nitrogen Nitrogen becomes becomes liquefied liquefied (heat (heat quantity quantity draw-off) draw-off) -- Rich Rich Liquid Liquid becomes becomes vaporized vaporized (heat (heat quantity quantity supply) supply)
Vaporized
RL
RL
GAN
Heat TRANSFER
LIN
PERU LNG -2009
25
Distillation
Vaporizer Vaporizer -- Condenser Condenser system system Upper part
Vaporized
RL
GAN
RL Heat TRANSFER
Vaporized RICH LIQUID
LIN
AN EXCHANGER IS LOCATED AT THE TOP OF THE COLUMN IN ORDER TO ACHIEVE THE HEAT TRANSFER BETWEEN RICH LIQUID AND GAN
EXCHANGER
RICH LIQUID bath GAN
LIN
APSA column PERU LNG -2009
26
Distillation
APSA APSA column column :: final final construction construction
VAPORIZED RICH LIQUID RICH LIQUID VALVE VAPORIZER - CONDENSER E02 RICH LIQUID BATH
GAN DRAW-OFF
K01
RICH LIQUID PIPE
GASEOUS AIR BOTTOM RICH LIQUID
PERU LNG -2009
27
Distillation
Reflux Reflux Ratio Ratio R R :: definition definition
GAN
L
V
L R= V Where: V = Vapor Flowrate (Nm3/h) L = Liquid Flowrate (Nm3/h)
AIR RL
PERU LNG -2009
28
Distillation
Reflux Reflux Ratio Ratio R R :: definition definition
L R= V
GAN GAN
Where:
V
L
L = V – GAN and
V = Air AIR
Consequently, R = f (GAN & Air flow rates) : AIR
R= LR
Air – GAN Air PERU LNG -2009
29
Distillation
Reflux Reflux Ratio Ratio R R variation variation
Incomming N2 amount Air
Outgoing N2 amount GAN
L/V
RL
Total
1000x79% = 400x100% = 400 790
600x65% = 390
790
1000x79% = 450x100% = 450 790
390
840
390/790= 0.49
GAN
340/790= 0.43
The column becomes less concentrated in Nitrogen : Consequently, the column becomes enriched in Oxygen
AIR The GAN purity decreases (O2 content increase)
LR
PERU LNG -2009
30
Distillation
Conclusion Conclusion :: Reflux Reflux Ratio Ratio impact impact
GAN
L
GAN R = L/V
V
% N2 GAN (GAN Purity)
AIR RL
PERU LNG -2009
31
Distillation
TECHNOLOGY TECHNOLOGY :: Packing Packing element element
AST (Advanced Sieve Trays)
DBenefits : • • • • •
Very efficient liquid vapour contact Low pressure drop (liquid film distribution) High operating flexibility (minimal / maximal gas load) High capacity (maximal gas load) Low inertia PERU LNG -2009
32
Distillation
TECHNOLOGY TECHNOLOGY :: Packing Packing element element
Structure: assembly of corrugated metallic sheets (aluminium).
PERU LNG -2009
33
Distillation
TECHNOLOGY TECHNOLOGY :: Packing Packing element element
The Liquid-Vapour contact is obtained by the division of the liquid on the corrugated-crossed sheets: the liquid film is drawn downwards by gravity while the gas (vapour) flows upwards through the perforations and the void spaces between the sheets.
Corrugatedcrossed aluminium sheets
Perforations
PERU LNG -2009
34
Distillation
Vaporizer Vaporizer Vaporizer Vaporizer -- Condenser Condenser
GOAL Dto condense gas at the top of the distillation column in order to ensure a liquid reflux in the column Dto vaporise Rich liquid fluid at a lower pressure in order to feed the turbine (APSA L/LE) or the booster (APSA LE)
GAN
PRINCIPLES DHeat exchange in an aluminium brazed Heat Exchanger DCounter flow arrangement DHeat flux from the Hot fluid to cold fluid DDriving force = temperature difference
AIR LR
PERU LNG -2009
35
Distillation
Vaporizer Vaporizer
E02 Vaporizer Vaporized RICH LIQUID -172°C
TECHNOLOGY : Bath type vaporiser
KEY COMPONENT FOR THE PRESSURE MAP AND FOR THE COLD PRODUCTION
SAFETY : in all cases the vaporiser must
be completely submerged
4.8b
RL + VRL
EXCHANGER T= 2°C RICH LIQUID bath
GAN
Incondensable gases
GAN
GAN -170°C LIN
9.7b LIN
APSA column
LIN RL PERU LNG -2009
36
Distillation
Vaporizer Vaporizer deconcentration deconcentration purge purge
AIR downstream the Air Purification still Contents some contaminants:
DHYDROCARBONS DN2O
A PART OF THESE COMPONENTS ARE STOPPED IN THE PURIFICATION UNIT
THE OTHER PART ENTER IN THE COLD BOX
DThe light components go up (ex: H2,…) DThe heavy component go within the vaporiser bath (RL)
PERU LNG -2009
37
Distillation
Vaporizer Vaporizer deconcentration deconcentration purge purge
AMONG THESE HEAVY COMPONENTS, SOME ARE NOT VAPORISED
CONCLUSION : WITHOUT ANY PURGE IT COULD HAPPEN AN ACCUMULATION OF HYDROCARBONS WHICH CAN FORM EXPLOSIVE COMPLEXES WITH RICH LIQUID BATH
TO AVOID ACCUMULATION, THE BATH MUST BE PURGED PERMANENTLY
DECONCENTRATION PURGE :
DDIRECTLY LINKED TO THE SAFETY OF THE PLANT
PERU LNG -2009
38
MASS BALANCE
PERU LNG – 2009
1
7. Mass balance
7.1. Mass balance formula
Σ (inlet ) = Σ (outlet ) Residual Gas
AIR
APSA L
GAN
GLOBAL
MASS BALANCE
PARTIAL
MASS BALANCE
Σ inlet flowrate = Σ outlet flowrate Σ inlet flowrate,i = Σ outlet flowrate,i Σ inlet N flowrate = Σ outlet N flowrate 2
2
PERU LNG – 2009
2
7. Mass balance
7.2. Mass balance application
Residual Gas
GLOBAL
MASS BALANCE
QAir = QRes + QGAN PARTIAL
AIR
APSA L
MASS BALANCE
QN2,Air = QN2,Res + QN2,GAN xAir.QAir = xRes.QRes + xGAN.QGAN
GAN
where
QAir = inlet air flowrate xAir = inlet air Nitrogen composition PERU LNG – 2009
3
7. Mass balance
7.3. Mass balance exercise A
customer want to produce N2 at a purity of 1ppm O2.
Residual Gas
He
wants to use his air network producing 4000 Nm3/h.
A
AIR
APSA L
classical O2 content in the Residual gas is 30 % for such a plant.
Argon
is not considered in the calculation
GAN
How
Air
composition : 78.11 % N2, 0.93% Ar, 20.96% O2
much Nitrogen he will produce in these conditions ? PERU LNG – 2009
4
OVERVIEW OF APSA L CONTROL
PERU LNG – 2009
1
9. Process Flow Diagram : Warm Skid
PERU LNG – 2009
2
9. Process Flow Diagram : Cold Box
PERU LNG – 2009
3
9. Process Flow Diagram : LIN Storage
PERU LNG – 2009
4
GENERAL SAFETY
PERU LNG - 2009
1
Safety issues on APSA-L
General Safety Issues DGeneral hazards in industrial environment DHazards specific to ASU
CnHm related hazards DIdentification DPrevention
PERU LNG - 2009
2
General Safety Rules
What kind of risks ? DRunning machines DElectricity DPressure DNoise DUnder-oxygenation (Anoxia) DOver-oxygenation DCryogenic temperatures DHigh temperatures DBurning
PERU LNG - 2009
3
Example: Pressure hazard THE DANGER FROM PRESSURISED EQUIPMENT IS DUE TO THE QUANTITY OF ENERGY STORED IN THE DEVICE TO COMPRESS THE FLUIDS IT CONTAINS.
RGY CAN BE CONSIDERABLE!
THIS ENE
IN CASE OF RUPTURE: THIS ENERGY CAUSES ABRUPT EXPANSION OF THE FLUID.
LEAK AND BURSTING
EXPLOSION 31
PERU LNG - 2009
4
Example: Pressure hazard (continued) PIPING AND CONTAINERS COMPLIANT WITH CURRENT REGULATIONS
-> Design codes -> Scheduled inspections -> Tests
ALWAYS MAKE SURE THERE IS ZERO PRESSURE BEFORE SERVICE OPERATIONS
SAFETY MEASURES OBSERVE SERVICE OPERATION PROCEDURES
SAFETY DEVICES
REPORT ANY DEFECT OBSERVED ON A DEVICE, A PIPE OR SAFETY PART IMMEDIATELY
32
PERU LNG - 2009
5
General Safety Rules
Usual Hazardous works : D Work at high levels D Digging work D Hoisting and handling equipments D Traffic D Electricity D Machines D Work on piping or vessel D Welding D Sources of radioactivity
PERU LNG - 2009
6
General Safety Rules
Safety Management
Defining clearly responsibilities Approvals and qualifications
DQualified and trained workers DQualified subcontractors
Procedures DWork permit DElectrical / Mechanical isolation
Equipments DPPE DCertified tools / machinery
EIS Management?
PERU LNG - 2009
7
General Safety Rules
Usual Personal Safety equipment D Helmet D Safety glasses and adequate face shields for specific hazards (chipping, acid work, welding, molten metals …) D Ear plugs and noise-proof head sets D Safety shoes D Clean and Fire-proof clothing D Safety mittens or gloves D Protective masks with suitable filter D Safety belt or harness if necessary
PERU LNG - 2009
8
ASU Related Safety
Gas Hazards
Processed gases of ASU involve 2 main specific hazards 1) Inflammation or explosion 2) Anoxia
Inflammation or explosion D Causes • •
Presence of flammable gas in air Oxygen enriched atmosphere (more than 21% oxygen)
D Concerned zones • • • •
liquid oxygen filling station oxygen expansion valve station oxygen metering station liquid or gaseous oxygen vent PERU LNG - 2009
9
O2 gas hazard PROPERTIES
.GAS ENABLES AND MAINTAINS COMBUSTION.
SAFETY MEASURES
No leaks
DETECTION O 2%
COLOUR
After analysis
WITH AIR
if O 2 = 21%
NAME
IDENTIFICATION of pipes and storage locations.
Purge venting to the outside
PERU LNG - 2009
10
O2 gas hazard (continued) OXYGEN O 2 PERCEPTION DENSITY/AIR
Colourless, odourless, tasteless. d = 1.1
SPECIAL PRECAUTIONS
AIR
NORMAL PROPORTION IN AIR
21%
Detection with alarm if % O2 in air exceeds 25%. No grease, no oil.
EFFECT OF OXYGEN ENRICHMENT ON COMBUSTION Fuels ignite more easily. Flames much hotter and spread more quickly % O2 in air
25% 30% 50%
Effect on combustion
No particles. Clean clothing made from fire resistant textiles Controlled speed with slow manoeuvres.
FASTER COMBUSTION QUICK COMBUSTION
Floors clean and made from non combustible materials.
INSTANTANEOUS COMBUSTION EXPLOSION
PERU LNG - 2009
11
ASU Related Safety
Gas Hazards
Anoxia D 2 types • Sudden : less than 6% O2, victim falls down immediately • Slow : different steps, deeper breath, heart beats, no attention, thinking wrong, no fell pain ….
D Causes •
Gas containing not enough oxygen under an assimilable form by the human body
D Concerned zones • • • • • •
Inner cold box & Outer cold box Confined area or insufficiently ventilated Analysers rooms, or cabinets, control room Trenches or low points (sewer, pits…) When using cryogenic liquids (nitrogen, argon …) In vessels of the purification unit (desorption of beds) PERU LNG - 2009
12
N2 gas hazard Normal breathing
PROPERTIES
21% O2
Vertigo, headaches
GAS DOES NOT SUPPORT LIFE. WHEN THESE GASES ARE PRESENT: THE QUANTITY OF O2 DECREASES, ATMOSPHERE UNDER OXYGENATED, ASPHYXIA.
18% O 2 Asphyxia
0% O 2
SAFETY MEASURES DETECTION
No leaks
Alarm if O <18%
or
After analysis if O 2= 21%
If O2 < 18%
2
COLOUR
WITH AIR
NAME
IDENTIFICATION of pipes and storage locations.
Purge venting to the outside
PERU LNG - 2009
13
ASU Related Safety
Cold Hazards
General D Liquefied gas concentrates in a small volume big amount of matter
Effects D Every touch with liquefied gas causes frostbite similar to burn D Skin and lungs can be damaged by cold atmosphere D Lower the temperature, longer the touch, more serious effects are D Hypothermia can cause death
Safety rules D Do not touch cold material D Do not stay in a cold atmosphere D Do not walk in a zone where cryogenic liquid has flown D Do not purge voluntarily cryogenic liquids on the ground D Take care of wet clothes PERU LNG - 2009
14
ASU Related Safety
Operating in Heat Insulated Area
Perlite Insulation (cold box, exchanger box) D Perlite : hydrated silicate pre-submitted to an expansion D Highly irritant material to be handled with gloves, glasses and mask D Extremely light and fluid (a fall in perlite lead to death)
Rock-wool insulation (cold tank, exchanger box) D Highly itching material D Work in a tunnel highly dangerous (risk of collapsing)
Nearly all heat insulated area are considered CONFINED SPACE Î specific entry rules apply
PERU LNG - 2009
15
HYDROCARBONS SAFETY
PERU LNG 2009
1
Hydrocarbons Safety
1.
CnHm Hazards: Explanations
D 1. Risks related to the impurities in the bath type vaporizers D 2. Right/wrong operation of the E02 vaporizer D 3. Right/wrong operation of the front end purification (FEP)
2.
Hazards Controls:
DThe 8 Golden Rules
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Hydrocarbons Safety
Some characteristics of the main impurities present in the atmosphere Impurity
Formula
Normal
Solubility
Inflamability Equilibrium
content
Limit in LOX
limit
coefficient K
in air
at - 181°C
in O2
in LOX
in ppm
in ppm
in ppm
at - 181°C
Methane
CH4
<5
no second phase
54000
0.3
Ethane
C2H6
< 0,5
128 000-250 000
30000
5,2 E-5
Ethylene
C2H4
< 0,5
13 000-30 000
27000
2,0 E-3
Acetylene
C2H2
< 0,5
4-6
25000
3,4 E-2
Propane
C3H8
<1
9 800
21000
5,0 E-7
Propylene
C3H6
<1
3 600 - 6 700
21000
5,0 E-6
n Butane
nC4H10
<1
700
18000
1,3 E-10
Carbon dioxide
CO2
< 400
4-5
3,3 E-3
Nitrous oxide
N2O
< 0,6
140 - 160
7,0 E-4
O3
< 0,1
no second phase
Ozone
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Hydrocarbons Safety
Bath type vaporizer operation (APSA-L)
Internal type (main vaporiser E02) LRV
LP
Important RECIRCULATION of liquid (thermosiphon effect): - around 1 Nm3 vaporised * Rare gases purge Ne, He, H2
- for 50 Nm3 of non-vaporised LR *
LR Purge
GAN & LIN Prod.
HP
* figures corresponding to an exchanger completely immersed PERU LNG 2009
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Hydrocarbons Safety
Proper and Wrong operation of a bath type vaporizer Normal operation Gas = 100 Nm3/h + Liq = 5000 Nm3/h N20 = 41 ppm
Reduced feed Liq = 25 Nm3/h N2O = 160 ppm
Gas = 100 Nm3/h N20 =100 ppb
DEPOSIT N2O
Heat to vaporise 100
Liq = 5100 Nm3/h N20 = 40 ppm
Heat to vaporise 100
Liq = 125 Nm3/h N20 = 40 ppm * * considering CO2 in that case, only 1 ppm in the feed would lead to deposit PERU LNG 2009
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Hydrocarbons Safety
Proper and Wrong operation of a bath type vaporizer CORRECT VAPORISATION
DRY VAPORISATION GAS LIFT STOPPED
TOO LOW LEVEL Gas lift in normal operation. Recycling = up to 50 times the vaporised flowrate
Solubility limit is reached. Deposits of CnHm, CO2 or N2O are building up Concentration is increasing
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Hydrocarbons Safety
Proper and Wrong operation of a bath type vaporizer DISTILLATION after pluging of a channel in the vaporiser Pluging by solid : - suspended solids (aerosol of oil - dust of adsorbent) - dissolved impurities CO2, N2O after reaching the solubility limit. Then concentration in liquid impurities (CH4 - C3H8 - C2H6)
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Hydrocarbons Safety
Proper and Wrong operation of a bath type vaporizer Normal Operation: Excess liquid flowing out No concentration
Dry Boiling: No liquid out Concentration build up
Normal level
Low level
Deposit starts if liquid gets saturated and Contaminants cannot be eliminated with the gas phase
Low level
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Hydrocarbons Safety
Application: APSA-L – E02 Vaporizer
CnHm enter
LRV VAPO E02
αIN × QIN
αLRV × QLRV αLR × QLR
LR
PI 4.2 barg
CnHm exit
QAIR QAIR αLR = αAIR ≈ αAIR K × QLRV + QLR QLR Purge PurgeRate Rate==0.2% 0.2%of ofAIR AIRFLOW FLOW Concentration Concentrationfactor factor==500 500
Air Aircontent content CH CH44 == 55ppm ppm CC2HH6 == 0.2 0.2ppm ppm 2 6 CC2HH2 == 0.5 ppm 0.5 ppm 2
2
LOX LOXcontent content CH CH44 == 2500 2500ppm ppm CC2HH6 == 100 ppm 100 ppm 2 6 CC2HH2 == 250 250 ppm ppm 2
2
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Hydrocarbons Safety
Adsorption Principles
H2O and CO2 free air
The Front End Purification (FEP) is designed to stop completely : D H2O D CO2
But other impurities from the air pass through the adsorber before CO2 : D D D D D
CH4 C2H6 C3H8 N2O C2H4
Air with all contaminants
Methane Ethane Propane Nitrous Oxide Ethylene
REACTIVATION ADSORPTIO N
And Andmay mayenter enterinto intothe theCold ColdBox Box PERU LNG 2009
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Hydrocarbons Safety Adsorption capacity of Front End Purification total Front end purificaton
H2O, CO2, nC4H10, C2H2, O3.
partial
none
C3H8, NO
N2O, NO2, C2H4
H2, CO, CH4, C2H6
ADSORPTION LEVELS
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Hydrocarbons Safety
Contaminants dangerous for the purification
Some CONTAMINANTS can badly damage the molecular sieves They are mainly: - the acid gases : CI2, SO2, H2S etc., NH3 - miscellaneous organic molecules
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Hydrocarbons Safety
Potential hazards in the Front End Purification
Abrasion of a part of the adsorbent (velocity too high) D Risk of channeling = by pass flow D Risk of lower adsorption capacity D Risk of introducing adsorbent dust in the cold box
Internal bypass of the beds, by leakage Liquid water carry-over (separation problem) : D CO2 adsorption capacity is reduced if water vapor reaches the molecular sieve D A part of the adsorbent can be destroyed
Presence of some aerosols which go through the FEP Presence of dangerous contaminants in the mole sieve Too long adsorption phase : D “break-trough” of CO2 or H2O Example of CO2 entering an APSA L4 : -10 ppb of CO2 entering continuously : 2 kg per year -2 ppm of CO2 during 15 minutes : 15 grams of deposit PERU LNG 2009
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Hydrocarbons Safety Triangle of FIRE applied to E02 Vaporizer
ER EN
Velocity of gaz / liquid? Ozone decomposition ? Static Electricity ?
GY
CnHm deposits CnHm dissolved Aluminium
FU EL
OXYGEN LR Purity Liquid state
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Hydrocarbons Safety
Event sequence to explosion Spontaneous ignition of reactive material on Aluminum platefin main vaporizer in cold box
Combustion of accumulated hydrocarbon contaminants on Aluminum vaporizer cores
Presence of airborne fuel - aerosols light hydrocarbons concentration/accumulation in LOX & on Aluminum surfaces with N2O or CO2 ice & dry-boiling
Explosive rupture of cryogenic distillation column
Flash vaporization of cryogenic liquid
Massive runaway combustion of Aluminum exchangers in oxygen (exothermic reaction)
Uncontrolled escalation to explosion
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Hydrocarbons Safety
Risks related to the impurities in the vaporizers
During the operation of the ASU, the concentration of impurities in the bath of the vaporiser may lead to strong explosions : - Hydrocarbons, such as Ethane, Propane, Ethylene, Acetylene, or aerosols, can concentrate and/or deposit. The Lower Inflamability Limit is reached in LOX - Ozone is a strong ignition agent These explosion hazards exist when there is a lack of LOX (LR) feed into the passages, caused by : - Too low level of the bath of the vaporiser - Plugging of passages by solid deposits: CO2* , N2O*, dust... * Risk of accidental deposit of CO2 or N2O, due to their low solubility in LOX, 5 ppm and 160 ppm respectively.
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Hydrocarbons Safety
Possible Damage Overview
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Hydrocarbons Safety
How to control the CnHm hazards
The 8 GOLDEN RULES D1. Environmental Survey D2. Operation of FEP D3. Operation of Vaporizer D4. Deconcentration purge D5. Periodical Deriming D6. Control of the transient phases D7. Control of other sources of pollution D8. EIS management
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Hydrocarbons Safety
1. Environmental Survey 1. Surrounding industries and distances 2. Atmospheric conditions 3. Air analysis 4. Communication with surrounding industries The plant operator shall maintain an environment file including following information : D Nearby industries liable to release gases D Distances between those potentials sources and the air intake of the ASU (+ height of sources) D Presence of haze (organic aerosols)
Polluted site or Not ?
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Hydrocarbons Safety
2. Operation of FEP Complete retention of CO2 in FEP is of vital importance for the unit (low solubility in RL : 5 ppm at –181°C) Air conditions evolutions have an impact on :
D Mass Flow Rate D Pressure D Temperature D Duration of the adsorption D Air Cleanliness
Regeneration conditions act on : D Regeneration gas flow rate D Duration of heating D Heating temperature
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Hydrocarbons Safety
2. Operation of FEP
FEP performance control : CO2 content analysis at outlet D 1 ppm D 3 ppm
Alarm Shutdown of the unit after 15 minutes
Control of the desorption effectiveness : temperature peak D Alarm in case of “no heat peak”
Recommended REGEX operation after CO2 breakthrough test (3 years)
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Hydrocarbons Safety 3. Control of the level of bath vaporizer Upper level tap (100%of the transmitter scale) Level sample 100% immersion (Level Set Point) 90% immersion (Low Level Threshold) 80% immersion (Very Low Level Threshold) Height, m
70% Lower tap of LT2
LT2
LT1 2nd transmitter = improvement
0% immersion Lower level tap for LT1 (0% of LT1)
Plant Shutdown after 1 hour Transmitters:
• Calibration using the heights and the density of the liquid • Check with level sample gauge
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Hydrocarbons Safety
4. Deconcentration Purge Deconcentration line: 1/2”.LR.04 Deconcentration type: intermittent purge (but permanently in service) Deconcentration volume: at least 0.2% of the air flow Deconcentration control: sequence linked to the level of vaporizer E02
D Time of purge is constant D Level drop is monitored D Alarm is raised in case of low level drop
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Hydrocarbons Safety
5. Periodical Deriming
The objective is to vaporize any contaminants which may have entered in the equipment of the cold box D Every 3 years D Applied to cold box equipment only (compressor and FEP are running independently) D Deriming operation • Low pressure • High flow
D Deriming mean • Dry air • Usually ambient temperature • Exceptionally hot temperature (65°C is the limit for the aluminum heat exchanger)
D Refer to PFD PERU LNG 2009
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Hydrocarbons Safety
6. Transient Phases
Start-up D As much liquid production as possible D Minimum air input D Liquid assist after first liquid production (LIN only)
Shut-down D Drain ALL liquid after 48h shut-down D Drain if E02 level is below 80% immersion
Change of run-type D Maintain vaporizers level
Normal run D Control of frosted pipes and dead-ends
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Hydrocarbons Safety
7. Other sources of pollution
Machine: Turbine D Lubricated machine D Seal gas pressure
Instrument air D Usually: dry air D Back-up ?
Air intake D Car parking, Truck unloading D Hot works, fires... D Exchanger water leak...
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Hydrocarbons Safety
8. E.I.S Management
E.I.S = Element Important for Safety D Safety Protection Loops D Alarm and Shutdowns parameters • Set-points • Delay • Hysteresis
D Qualified personnel
Management of Change
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Hydrocarbons Safety
Conclusions Hazard Hazardisisaacombination combinationof of AApolluted pollutedatmosphere atmosphere AAnot notproper properoperation operationof ofthe thevaporizer vaporizer
Can Can lead lead to to severe severe accidents accidents THE THEGOLDEN GOLDENRULES RULES 1. 1.Environmental EnvironmentalSurvey Survey 2. 2.Operation Operationof ofFEP FEP 3. 3.Operation Operationof ofVaporizer Vaporizer 4. 4.Deconcentration Deconcentrationpurge purge 5. 5.Periodical PeriodicalDeriming Deriming 6. 6.Control Controlof ofthe thetransient transientphases phases 7. 7.Control Controlof ofother othersources sourcesof ofpollution pollution 8. 8.EIS EISmanagement management PERU LNG 2009
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DERIMING AND EXCEPTIONAL REGENERATION
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1. Deriming Procedure
Deriming and Drying Procedure
Purpose DRemove contaminants in every locations they are subject to accumulate DAccelerate to warm up of the plant after a shutdown
Main recommendations DAll liquids should be completely purged before starting deriming DStart deriming with all valves closed D6 phases in order to defrost progressively the plant DProceed from a clean circuit towards a dirty circuit DUse the lowest pressure possible DKeep the deriming outlets wide open DControl the deriming flow rate in order to avoid high velocities
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1. Deriming Procedure
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1. Deriming Procedure
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2. Exceptional Regeneration
Purpose D Remove impurities not desorbed during regular reactivation D Exceptional procedure to avoid any damage
Carry out : D At initial start-up • To clean from contaminants accumulated during transportation • To control adsorption capacity respect to design capacity
D After an pollution accident • Late reversal • Liquid water from R02 • Unusual temperature at the inlet of the dryers
D After repetitive CO2 “break-through”
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2. Exceptional Regeneration
Highlights D Passing dry gas at low pressure and increased temperature D Long period of time through the bottle (24 hours at least) D Temperature in the bottles may range from 230 to 290°C D Temperature increase : two steps to avoid damage of adsorbents Temperature
Outlet electrical heater
290°C
Bottle bottom ~ 240°C 145°C ~120°C
Phase 1
Phase 2
Effective Effectivepart partof of exceptional regeneration exceptional regeneration
Phase 3
Phase 4
Time
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2. Exceptional Regeneration Q(WN 2) )==121 Q(WN 121Nm3/h Nm3/h 2 PP(V-6701 A) = 1.033 (V-6701 A) = 1.033bar barabs abs TITI513 outlet = 240°C 513 outlet = 240°C
ATM
EH-6701 PV 561 From Exchangers
KV 540
TI 580
Instrument Air Deriming Air To Exchangers
V-6701 A
V-6701 B
ATM
KV 515
TI 513
ATM
AIR C01
Inlet Water Outlet Water PERU LNG 2009
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PERU LNG NITROGEN GENERATOR SYSTEM TRAINING
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NITROGEN GENERATOR TRAINING 1. Process description APSA L 2. Air Purification Unit 2. 1 Exceptional Regeneration 3. Turbine Expanders 4. Cold box – warm standstill 5. Production 6. Trip and shutdown 7. Start up cold standstill 8. Control loop description 9. Stutdown
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1. Process description APSA L
Compression
Purification
Heat exchange
Cold production
Distillation
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2. Air Purification Unit To start it we should do a “Initialization”; for this the inlet valve should be close and the inlet pressure PT_502 at 0 bar. You choose the bottle which be in regeneration and press initialization button. The Bottles will place in HP isolation step. You open inlet valve FV_580 to pressurize the bottle on line and the HP cold box Open it to have enough flow for regeneration. You should open the KV_540 to send air in regeneration bottle and put the PV_561 in auto mode with SP at 160 mbar. When flow from cold box is enough you close KV_540. When the timer step is done and you have all condition, a indication “Next step” appear you can move manually the sequence by Next step button If you need to move all the sequence you have a Bypass button to bypass the heating and cooling timer. But this don’t bypass other step. If all is correct you should put the sequence in auto mode in order to avoid CO2 breakthrough. You can open air production valve FV561 and put in auto SP 750 AIR Nm3/h In case of problem you must put the sequence in manual mode and check the problem. PERU LNG 2009
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2. Air Purification Unit 1. High Pressure Isolation Isolation of the bottle in adsorption Timer step 360s
Cold Box N2
2. Depressurization The bottle is slowly depressurized in opposite direction to the adsorption flow. Drop pressure of bottle should be done during step timer else we have “Depressurization to long” and stop the sequence. Timer step 300s
KV_540
cold box
heater
Cold Box N2
KV_540
cold box
heater
KV_530
KV_530
V-6701A
V-6701B
Hp isolation
In service
V-6701A
V-6701B
Hp isolation
In service
venting
venting
KV_515
KV_525
KV_515
KV_525
KV_516
KV_526
KV_516
KV_526
KV_510
KV_520
Air
KV_510
KV_520
Air
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2. Air Purification Unit 3.Blow-off Start to send flow thought the bottle. We should have minimum 8 mbar of DP on heater else Alarm ”EH-6701 Heater low flow”. Timer step 60s Cold Box N2
KV_540
cold box
heater
4.Heating The heater starts to increase temperature at around 150°C In case of the outlet temperature is always < 135°c after 15 min Alarm «Heater start fault » Timer step 45mn Cold Box N2
KV_540
cold box
heater
KV_530
KV_530
V-6701A
V-6701B
Blow Off
In service
V-6701A
V-6701B
Heating
In service
venting
venting
KV_515
KV_525
KV_515
KV_525
KV_516
KV_526
KV_516
KV_526
KV_510
KV_520
Air
KV_510
KV_520
Air
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2. Air Purification Unit 5. Cooling The heater is turned off and we keep the waste nitrogen Flow to cold down the adsorbent. If the outlet heater temperature is not drop less 50°c in 10min: Alarm « Stop heater fault » Timer step 75min Cold Box N2
KV_540
cold box
heater
6. Low Pressure Isolation Isolation of the bottle regenerate Timer step 120s
Cold Box N2
KV_540
cold box
heater
KV_530
KV_530
V-6701A
V-6701B
Cooling
In service
V-6701A
V-6701B
LP isolation
In service
venting
venting
KV_515
KV_525
KV_515
KV_525
KV_516
KV_526
KV_516
KV_526
KV_510
KV_520
Air
KV_510
KV_520
Air
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2. Air Purification Unit 7. Pressurization The bottle is pressurized with purified air from the outlet of the other bottle. If the pressure don’t increase 2 Alarms “Pressurization to long” and “Bottles DP to high” Timer step 1332 s
8. Parallel The purpose of this step is to reduce the temperature of the purified gas entering the exchangers: Timer step 60s
Cold Box N2
Cold Box N2
KV_540
cold box
heater
KV_540
cold box
heater
KV_530
KV_530
V-6701A
V-6701B
Pressurization
In service
V-6701A
V-6701B
Parallel
In service
venting
venting
KV_515
KV_525
KV_515
KV_525
KV_516
KV_526
KV_516
KV_526
KV_510
KV_520
Air
KV_510
KV_520
Air
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2. Air Purification Unit Temperature Inlet temperature
Heater temperature
Cold Desorption
Outlet temperature
Hot Desorption heater pick
Blow off temperature
Heating
Cooling
Time
Total Time on line 160 min; Heating Temperature 150°C In case of trip you should note the bottle in regeneration and the bottle on line with the time of both in order to restart on same position. PERU LNG 2009
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2. 1 Exceptional Regeneration The exceptional regeneration is done only on firth start up and after stop maintenance each 2 years. Or if you make a C02 breakthrough. You should do it in manual mode and activate the Regex button. 290°C
150°C
120°C
PHASE 1
PHASE 2
PHASE 33
PHASE 4 PERU LNG 2009
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2.1 Exceptional Regeneration Phase 1 The first heating step is equal to a normal regeneration. Start flow to EH-6701 and Temperature at 150°C When outlet temperature reach 120°C start phase 2 Depending of the amount of water adsorbed on the alumina, the duration of phase 1 is expected to be 2h to 4h.
Phase 2 The temperature should reach 290°C, adjust the regeneration flow to this. When outlet temperature is at 230°C start phase 3. The expected time of this phase is about 2 h to 3h.
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2.1 Exceptional Regeneration Phase 3 Depending on the heat loss, a final temperature of approximately 230°C is reached at the outlet of the vessel for exceptional regeneration. The gas at the outlet of the heater is still at 290°C. Hold the temperature for 6 to 9 hours.
Phase 4 Turn off the heater (cooling step of the normal sequence) and wait until the temperature at the outlet of the bottle indicates 25°C. The expected time of this step is about 4 h to 6 h
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3. Turbine Expanders RTS No low oil tank level and oil temperature > 24°C Pressure seal gas > 1.5 bar Request Button to start the oil pump Oil pressure > 6,5 HP Column level not high Inlet valve close Nozzle valve close.
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4. Start up Cold Box – warm standstill The cold box must be start only after drying, in order to remove totally the water. Some dew point should be done at different point and we should have around - 60°C. The derimming procedure can be use to be sure all lines are dry. - Cooling down: When the compressor running the HP column is pressurized. You start to make flow by opening the FV_565B and put it in Auto mode witch SP at 60% of nominal flow ~2700Nm3/h. You open the HV_502 at 60% to make flow through the E-6702. Open the LV_564 fully to start flow on LP column and send gas to the turbine and put the PV_590 in auto mode with SP at 4 bar.
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4. Cold box – warm standstill The oil pump turbine was started and you have the RTS. Open the isolation valve HV_562, the turbine will run at low speed. Open slowly the Nozzle valve by the LIC_552 in manual mode to increase the speed more than 7000 Nm3/h in 2min else you trip. Increase the nozzle opening to close the PV_590 but take care at pressure of LP column and speed of turbine maximum 35 000 rpm Monitoring the outlet temperature TI_558 to don’t reach -180°C This cold will cold the main exchanger E-6701 and decrease the air temperature monitoring on TI552A. Be careful the TI_582 and TI_565 outlet exchanger should be stay warm. The cooling of E-6702 and LP column is monitoring on TI84A and TI556. PERU LNG 2009
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4. Cold box – warm standstill With the temperature drop the flow will increase Put the FIC_580 in Auto mode to control inlet flow, the SP would be adjusting in order to have a homogeny cooling and not so fast around -1°c by hour to avoid any stress on columns and pipes The first liquid appear in HP column, at around 30% open purge to evacuate it, and after the liquid in LP column. When the liquid are rebuild, close the HV_502 at 50%. Adjust the turbine load and put the LIC_552A in auto mode SP at 45% Put the LV_564 in auto mode SP at 100%
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5. Production Gan Production: When the cold box is stable and the purity AIT_568 is < 50 PPM Put FIC_580 in Cascade mode and insert the flow request on HIC565 Activate the Gan Production Button. This will put in auto mode the flow controller FIC_565A with SP the HIC565 and adjust the FIC77B SP at 5% less in order to send gas to customer; If consummation is enough the FV_565B valve will be totally close and in case of flow degrease or stop the valve will adjust the flow out of cold box. In case of purity come > 200 ppm the valve FV_565A will close and when the purity came back the valve will open automatically.
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5. Production Lin Production: The Lin production can be activate only if the turbine run, if we have enough liquid in HP column and a good purity. If the pressure PI606/PI626 < 9.8 bar and LI605/LI625 < 90%. This activation will increase the air inlet flow of 6%.
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6. Trip To avoid unit trip directly the faults are separated but after some delays if no action are take the unit will trip. -
Dryer sequence stop. I20T D Air to V-6701A delta pressure is too high during pressurisation of V-6701A (PI_502 – PI_512) (UA502A) D Air to V-6701B delta pressure is too high during pressurisation of V-6701B (PI_502 – PI_522) (UA502B) D V-6701A depressurization step is too long (UAn52A) D V-6701A pressurization step is too long (UAn52B) D V-6701B depressurization step is too long (UAn55A) D V-6701B pressurization step is too long (UAn55B) D Electrical heater EH-6701 heating start failure (UAn57A) D Electrical heater EH-6701 heating stop failure (UAn57B) D Heater flow end tempo alarm PDALL_534 (PDALL_534) D Outlet C02 analyse alarm too high (AAHH542)
If this condition appear the cycle is stop and a timer of 15 min start. If the problem is not resolve you activate next trip.
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6. Trip Turbine TRIP DEmergency stop (HS584) DOutlet turbine temperature alarm too low (TALL558) DTurbine seal gas too low pressure (PALL570) DTurbine oil too low pressure (PALL572) or (PSLL575B) DTurbine speed alarm low (575Turbine speed alarm too high (SAHH575) or (SSHH575) DTurbine vibration alarm too high (VAHH575) DTurbine oil pumps off (ES_586A&B) DTurbine oil return temperature alarm too high (TAHH571) DUnit Shut Down The trip of the turbine don’t trip the cold box but after some time you will lose the liquid level.
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6. Trip
Cold Box TRIP D D D D D D D D D D D D
Condenser E-6702 level alarm too high (LAHH551) HP column C-6701 level alarm too high (LAHH552) Condenser E-6702 level alarm too low (LALL551) + Gan prod Condenser E-6702 not submerged alarm (LALL564) + Gan prod Emergency button (HSn53) Gaseous Nitrogen temperature alarm too low (TALL565) Waste oxygen temperature alarm too low (TALL582) Condenser E-6702 level alarm low (LAL551) + Gan prod + Turbine off Instrumentation air pressure too low (PAL550) Unit Trip Instrumentation open loop ESD
Close Lin Production and Gan Production FV_565A the valve B will open. Open LP column purge when level come high.
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6. Trip Unit
TRIP
DESD DInlet air pressure too low (PALL502) DAir Purification Shut Down > 15 min DEmergency switch HS n53 DInlet Air temperature alarm too high (TAHH 502) 30sec delay. DWaste Oxygen pressure alarm too high (PAHH 571) 30sec delay. DCold box trip DCnHm purge trip 24hr delay DCnHm alarm too high (AAHH_584) 24hr delay DCold box inlet air temperature alarm too high (TAHH_580) DInstrument air header pressure low ( PALL 550) DOperator stop Reduce N2 Production request at 2250 Nm3/H Trip APU; Cold Box; Turbine Action more: Inlet air valveFV_580at 15%.
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7. Star up – Cold standstill To start we should not be in level high alarm in Hp column and LP column, purge liquid if you need. Start the oil turbine system When compressor and Apu have started and in auto mode. Put the LV_564 in auto with Sp at 100% in order to keep level in LP column Start flow with the FV_565B SP 2700Nm3/h. When turbine is RTS start it in manual mode, increase speed higher than minimal at this moment the level in the vaporizer will start to increase and decrease according to the pressure fluctuation until the PIC590 stabilizes the pressure. When all is stable put the LIC_552A in auto. Be careful the temperature decrease faster than Warm standstill. Also the flow increase so put the FIC_580 in auto mode. When the purity come back start the production PERU LNG 2009
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8. Control loop description PIC 561 D Waste gas pressure outlet turbine control Functions: 1. ensure that enough residual gas is going through the heater (PV_561 closed) for regeneration of the adsorption bottles 2. maintain the turbine discharge pressure stable
If the pressure PI561 then the valve PV_561 Action direct This controller must remain in automatic mode Typical set point = 160 mbar NB: forced jump at every bottle change-over (+/- 20%) PX 561
PIC 561
PT 561 COLD BOX
E-6701
Silencer
PV_561
Atm
V-6701AV-6701B
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8. Control loop description PIC 590 D E-6702 Condenser pressure AND D01 inlet pressure Functions: 1. Maintain E-6702 condenser pressure stable in order to keep a column pressure stable 2. AND keep the turbine delta P constant If the pressure PI590 then the valve PV_590 Action direct This controller must remain in automatic mode Typical set point = 4,2 bar
PIC 590 PT 590
E-6702
PV_590
D01 D01
To V6701A/V6701B PERU LNG 2009
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8. Control loop description
FIC 565A
D Gaseous nitrogen to customer Function: Limit the nitrogen flow to the network at the requested flow available from the cold box. If the flow FI565 then the valve FV565 Action reverse The set point: SP565A = HIC565 (In Cascade mode) (HIC565 => GAN request by the operator on the DCS) FX 565 PT 565 GAN
C-6701
FT 565
FIC 565A
FY 565A
<
PIC 556 PT 556
TE 565
To GAN Network
E-6701 FV615A
PERU LNG 2009
26
8. Control loop description
FIC 565B D Gaseous nitrogen to the vent Function: Maintain a (nearly) constant flow out of the cold box if the flow to the network is lower than the requested flow. If the flow FI565 then the valve FV_565B Action reverse In cascade mode the set point: SP565B = SP565A -5% (Calculated by the PLC) FX 565 PT 565
FT 565
FIC 565B
TE 565 S04t
GAN
C-6701
E-6701
Silencer
ATM
FV_565B
PERU LNG 2009
27
8. Control loop description
FIC_580 D Control the air flow at the inlet of the cold box Function: Maintain a constant air flow to the Cold Box If the flow FXI580 then the valve FV_580 Action reverse In cascade mode the set point is calculated according to the nitrogen requirement RSP580 = (A * HIC565) + HIC502BG +- AIC565 (A is the extraction ratio adjusted during start-up) HIC565 GAN request by operator HIC502BG Bias request by operator AIC565 Can be increase or decrease SP value 500 Nm3/h
HIC 565BG BIAS Request
FX 580 V-6701A V-6701B
C01 C01
FIC FIC
SP
FIC FIC
HIC 565 GAN Request
PT 580
FT 580
TE 580
AIC 565
FV_580
+- 500 Nm3/h AIR TO COLD BOX PERU LNG 2009
28
8. Control loop description
LIC_552A
D Column C-6701 Level Function: Keep a sufficient cold production when the plant is running in “Gas mode”. The output of this controller is acting on the turbine nozzles If the level LI552 then the valve HV_573 Action reverse Typical set point = 45 %
D01 D01
C-6701
LIC 552A
LT 552
PERU LNG 2009
29
8. Control loop description
LIC_552B D Column C-6701 Level Function: Control the column level while the plant is running in « liquid production mode ». The output of this controller is acting on the LV552B If the level LI552 then the valve LV552B Action direct Typical set point = 45 % (same as LIC_552A)
LV552B
LIN STORAGE
C-6701 LT 552
LIC 552B
PERU LNG 2009
30
8. Control loop description
LIC564 D Condenser E-6702 Level Function: Maintain always the E-6702 condenser level above the top of the condenser by liquid transfer from C-6701 to E-6702. If the level LI564 then the valve LV_564 Action reverse The set point = 100 % immersion. For safety reason (to avoid dry vaporization and then hydrocarbon concentration), it must be respected. Automatic mode. LIC 564
E-6702
LT 564
LV_564
C-6701 PERU LNG 2009
31
8. Control loop description
SIC575 D Turbine speed controller Function: Maintain the speed to the nominal value by acting on the Inlet Guide Vanes (IGV’s) If the speed SI575 then the IGV’s HV_573 Action reverse This controller is generally not used because the IGV’s are normally controlled by LIC_552A HV_573
D01 D01
ST 575
SIC 575
PERU LNG 2009
32
8. Control loop description
Oil Brake valve D Turbine oil flow adjustment Function: This is not a controller, it just allows you to act manually on the oil brake and by this mean, adjust the frigorific capabilities of the turbine. It is adjusted manually to change between LIN and GAN runs If the valve is , the speed and the power Action reverse This valve must never be totally closed in order to avoid any over speed or any damage in the cartridge by over heating of the oil. The oil temperature should never exceed 100°C
PERU LNG 2009
33
9. Shutdown Shutdown Before stop the plant to be sure Nitrogen backup work properly and the air instrumentation backup is available. To shut Down the plant you can put the Operator stop button this is equal at unit trip or unload each part and stop it. The check valve CVW011 will close to avoid liquid purge go back to waste line. It is better to stop Air Purification Unit after a complete regeneration of bottles in order to restart on this. If the plant is stop less than 48 hours we can keep the liquid inside monitoring by hydrocarbon analyzer. To be sure valve PV_590 and PVn89 are in auto mode and the HV_502 is fully open to control pressure. If it is more than 2 days the liquids must be drain to avoid concentration of hydrocarbon and if it is for maintenance the plant should be warm up. PERU LNG 2009
34
