© 2006 Dresser-Rand
Centrifugal Centrifugal CompressorsCompressors
© 2006 Dresser-Rand
TopicsTopics
Centrifugal Compressor Model
How a Centrifugal works / Energy Conversion
Centrifugal Flowpaths
Performance Curves
Operation Limits: Surge & Overload
Factors Affecting Compressor Performance
Operational Issues – Optimizing CompressorEfficiency
© 2006 Dresser-Rand
Axially or Horizontally Split CompressorAxially or Horizontally Split Compressor
© 2006 Dresser-Rand
Radially or Vertically Split CompressorRadially or Vertically Split Compressor
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Radially Split with Shear Ring HeadsRadially Split with Shear Ring Heads
Shear Ring
O-Rings
Retaining Ring
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Shear Rings & OShear Rings & O--RingsRings
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The Centrifugal EffectThe Centrifugal Effect
MomentumVelocity & Direction
Centripetal Force
Centrifugal Reaction
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Gas Velocity IncreaseGas Velocity Increase
V1
V2
V3
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Gas Impeller Exit AngleGas Impeller Exit Angle
•© 2004 by Dresser-Rand
Exit Path Due to Backward Curve
Low Flow Exit Path
Exit Path atRated Flow
TangentExit Path
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Centrifugal ActionCentrifugal Action
EYE OF THEIMPELLERLow Velocity, Low Pressure Gas Inlet
TIP OF THE IMPELLERHigh Velocity, Higher Pressure Gas Outlet
Cover Blades Disk
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ImpellersImpellers
Manufacturing• Cast• Riveted• Welded
Two PieceThree Piece
Types• Open• Semi-Enclosed• Enclosed
Cover Blades Disk
Hub
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Polygon Fit Impeller Rotor AssemblyPolygon Fit Impeller Rotor Assembly
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Centrifugal Action Diffusion PassageCentrifugal Action Diffusion Passage
P1 P1
P2P2
Diffusion Passage
Impeller Impeller
Diffusion Passage
Shaft
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Diffusion Passage CrossDiffusion Passage Cross--Sectional AreaSectional Area
Diffusion Passage
Diffusion Passage
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V1 V1
V2V2 V1
V1Diffusion Passage
Impeller Impeller
Diffusion Passage
Shaft
Diffusion Passage Velocity ChangesDiffusion Passage Velocity Changes
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Pressure, Volume and TemperaturePressure, Volume and Temperature
1 ft.
1 ft.1 ft.
Gas = 1 ft.3
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Temperature and Molecule Energy Temperature and Molecule Energy LevelLevel
Greater Temperature = Greater Energy = Higher Pressure
© 2006 Dresser-Rand
Add Heat
1 ft.
1 ft.1 ft.
Gas = 1 ft.3
Pressure, Volume and TemperaturePressure, Volume and Temperature
© 2006 Dresser-Rand
What is a Stage of Compression?What is a Stage of Compression?Centrifugal Stage
Return Bend
Guide Vanes
Return Channel
Return Bend
ImpellerIncreases VelocityIncreases Static Pressure
DiffuserReduces VelocityIncreases Static Pressure
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Centrifugal Compressor StageCentrifugal Compressor Stage
© 2006 Dresser-Rand
Energy ConversionEnergy Conversion
P4,V4,T4
P2,V4,T2
P3,V1,T3
P3,V1,T3
P5,V1,T5
P1,V1,T1
P5,V1,T5
© 2006 Dresser-Rand
Centrifugal Centrifugal FlowpathsFlowpaths
Straight Thru or Series Flow
P1
P3 P5 P7 P9
BalancePiston
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Centrifugal Centrifugal FlowpathsFlowpaths
SS In
Series Flow with Sidestreams
P1
P5
SS Out
P7 P9P3
BalancePiston
© 2006 Dresser-Rand
Centrifugal Centrifugal FlowpathsFlowpaths
Compound Flow
P1
P5
P3 P9P7
BalancePiston
© 2006 Dresser-Rand
Centrifugal Centrifugal FlowpathsFlowpaths
Parallel or Double Flow
P1 P1
P5 P3P3
© 2006 Dresser-Rand
Centrifugal Centrifugal FlowpathsFlowpaths
P1 P5
D W
all
D W
a ll
Back to Back Flow with No Cooler
P5 P9
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BackBack--toto--Back Flow without a CoolerBack Flow without a Cooler
First Section Suction
Second Section Discharge
Cross-Over
Division WallSecond Section
Inlet
First Section Discharge
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Back to Back Flow with a Cooler
Centrifugal Centrifugal FlowpathsFlowpaths
P1
P9P5
P5
D W
all
D W
a ll
© 2006 Dresser-Rand
BridgeoversBridgeovers1 2 3 4 5 6 7 8 9 10
1 2 3 4 5 6 7
Bridgeovers
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BridgeoversBridgeovers
Bridgeover
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Inlet GuidesInlet Guides
Interstage Labyrinth Seal Grooves
Fit to Diaphragm
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DiaphragmDiaphragm
Diffusion Passage
Return Bend
Return Passage
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Inlet Guide In DiaphragmInlet Guide In Diaphragm
Outside Diameter of Impeller
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InterstageInterstage SealsSeals
Impeller
Shaft
InterstageLaby Seals
LocationLabyrinth
Seal
ShaftSpacer
LabyrinthSeal
LabyrinthSeal Labyrinth
Seal
Impeller ImpellerShaftSpacer
DiaphragmDiaphragm
Diffuser
P1
P2
P3
P3
P4
P5
Function
© 2006 Dresser-Rand
High Pressure
Low Pressure
Seal
Shaft
Labyrinth SealsLabyrinth Seals
Turbulence- Low Flow
Low Pressure
High Pressure
Shaft
Seal
High Pressure
Low Pressure
ShaftSeal with Worn Teeth
Laminar -High Flow
Wet Gas Condensate
Deposits
© 2006 Dresser-Rand
Hole Pattern Division Wall Seal with Hole Pattern Division Wall Seal with Swirl BrakeSwirl Brake
This design makes the seal insentive to preswirl even if the shunt is lost, which can occur during overload operation
© 2006 Dresser-Rand
Performance Curves Performance Curves and and
Surge ControlSurge Control
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Performance CurvesPerformance Curves
Head Concept
Basic Components
Fixed/Variable Speed
Surge/Overload
Effects on Performance
© 2006 Dresser-Rand
Head ConceptHead ConceptMechanical: The “work” (energy) developed to raise a
weight of 1 pound by a distance of one (1) foot. Expressed in foot-pound (or equivalent Kgm or Nm);
Gas Compressors: “ work” done by the compressor / amount of gas. The head expressed in feet, is the height to which the gas could be lifted
© 2006 Dresser-Rand
Head ConceptHead ConceptThe height to which the gas is lifted depends on the velocity
of the gas
For any given RPM, the head developed by the compressor is fairly constant, independent of the gas nature.
Head is depending upon:• Compressor geometry (i.e. no of stages, impeller diameters)• Compressor speed
Z: Compressibility Factor
R: Gas Constant = 1545 / MW
Ts: Suction Temperature (°R)
r: Pressure Ratio (Pd / Ps)
M: Polytrophic ExponentM:
© 2006 Dresser-Rand
Head Concept Head Concept –– ExampleExample
© 2006 Dresser-Rand
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Speed Lines
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Compressor Performance CurvesCompressor Performance Curves illustrates the operating range and flexibility of a given compressor
OverloadRegion
© 2006 Dresser-Rand
Compressor Performance CurvesCompressor Performance Curves
There are two types of curves that are generally required, section and overall:
• section refers to an impeller or sequence of impellers between two nozzles such that there is no pressure drop or temp reduction between impellers
• overall refers to a complete compressor or compressor train
Note: a back-to-back unit with a crossover may often be considered a two-section compressor; but with respect to performance curves, it is a single section since no pressure drop or cooling is introduced between the impellers
For single section compressors, the section curves and overall curves are one in the same
© 2006 Dresser-Rand
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DesignPoint
Design PointDesign Point is the point at which usual operation is expected and optimum efficiency is . It is the point at which the vendor certifies that performance is within the tolerance
© 2006 Dresser-Rand
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RatedPoint
Rated Point Rated Point is intersection on the 100 % speed line corresponding to the highest flow of any operating point
© 2006 Dresser-Rand
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DesignPoint
Stability:Stability: the percent of change in capacity between the rated (design point) capacity and surge (limit) point, all at constant speed, is measured as the stability of the centrifugal compressor. Indicates the capability of the centrifugal compressor to operate at less than design flow
© 2006 Dresser-Rand
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DesignPoint
Turndown:Turndown: the percent of change in capacity between the rated (Design point) capacity and the surge (limit) point, all at constant head or pressure is measured as turndown of the centrifugal compressor. Indicates the capability of the centrifugal compressor to operate at less than design flow
% Turndown
© 2006 Dresser-Rand
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Rise to SurgeRise to Surge:: the percent of change in discharge pressure between the rated point and surge limit at constant speed. High RTS means the compressor can accommodate a modest increase in discharge pressure with a little change in flow
% RTS
© 2006 Dresser-Rand
Surge Phenomenon Surge Phenomenon At any given speed, there is minimum flow, below which, the
compressor cannot be operated in a stable condition. This minimum flow value is called “surge “ point.
Surge is oscillation of the entire flow of the compressor system and this oscillation can be detrimental to the machine.
Compressor surge may be evidenced by the following:a) Excessive rotor vibrationb) Increasingly higher process gas tempc) Rapid changes in axial thrustd) Sudden changes in loade) Audible sounds (if surge is severe)
© 2006 Dresser-Rand
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Surge Region Design
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Surge DescriptionSurge Description Resistance to Flow Causes
Pressure to Rise Which
Causes Flow to Decrease
Sudden Reversal of Flow
Slams Thrust Disc Against
Inactive Thrust Bearing
© 2006 Dresser-Rand
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Surge Region Design
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Resistance to Flow Causes
Pressure to Rise Which
Causes Flow to Decrease
Sudden Reversal of Flow
Slams Thrust Disc Against
Inactive Thrust Bearing
Pressure Ratio Drops Low Enough
for Flow to Instantaneously
Build Back to the Design Curve
Pressure Builds along the
Design Curve Back
to the Design Point
Surge DescriptionSurge Description
© 2006 Dresser-Rand
Surge Control SystemSurge Control System
Input Signals Required1 - Suction Flow2 - Suction Pressure3 - Discharge Pressure
1
2
3Pressure
TransmitterPressure
TransmitterFlow
Transmitter
Surge ControlIn the PLC
RecycleValve
FT
Flow Element
PT PT
Suction
Discharge
I/P
PS
CPU
GBC
DI
COM
AI
AO
ETH
GBC
© 2006 Dresser-Rand
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Surge Control on Performance CurvesSurge Control on Performance CurvesOperating PointSurge Line
Control Line
© 2006 Dresser-Rand
Surge Control SystemSurge Control System
Input Signals Required1 - Suction Flow2 - Suction Pressure3 - Discharge Pressure
1
2
3Pressure
TransmitterPressure
TransmitterFlow
Transmitter
Surge ControlIn the PLC
RecycleValve
FT
Flow Element
PT PT
Suction
Discharge
I/P
PS
CPU
GBC
DI
COM
AI
AO
ETH
GBC
© 2006 Dresser-Rand
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Surge Control on Performance CurvesSurge Control on Performance CurvesOperating PointSurge Line
Control LineBackup Line
© 2006 Dresser-Rand
Surge ControlSurge Control
Performance Map
Surge Controller
© 2006 Dresser-Rand
Surge ControlIn the PLC
Blow OffValve
FT
Flow ElementPT PT
Suction
Discharge
I/P
PS
CPU
GBC
DI
COM
AI
AO
ETH
GBC
To Vent
© 2006 Dresser-Rand
PressureTransmitter
PressureTransmitter
FlowTransmitter
Surge ControlIn the PLC
RecycleValve
FT
Flow ElementPT PT
Suction
Discharge
I/P
PS
CPU
GBC
DI
COM
AI
AO
ETH
GBC
Cooler
© 2006 Dresser-Rand
Surge Surge –– Damage of Compressor Internals Damage of Compressor Internals
High axial displacement
Deformation due to high temperature
© 2006 Dresser-Rand
Surge Surge
The frequency of the surge cycle varies inversely with the volume of the system
If the check valve is located near compressor discharge nozzle, the frequency will be much higher than of a system with a large volume in the discharge upstream of the check valve
The higher frequency of the surge, the intensity will be lower (i.e. few cycles / minute up to more than 20 cycles / sec)
The intensity of the surge increases with gas density , pressure and lower temperature
© 2006 Dresser-Rand
Surge Surge -- Effects of Gas CompositionEffects of Gas Composition
Heavy Gas (propane, propylene)
Medium Gas (air, nitrogen, natural gas)
Light Gas (Hydrogen reach gases, i.e. hydrocarbon processing plants)
Q
E %
Surge points
Best Efficiency point
© 2006 Dresser-Rand
Surge Surge -- Effects of Gas CompositionEffects of Gas Composition
Observations made in respect to the heavy gas:
The flow at surge is higher;
The stage produces more head than corresponding to medium gas / light gas
The right side of the curve turns downward (approaches stonewall) more rapidly
The curve is flatter in the opening stage (small RTS)
© 2006 Dresser-Rand
External Causes and Effects of SurgeExternal Causes and Effects of Surge
Restriction in suction or discharge of system
Process changes in pressure, temperatures, or gas MW
Internal plugging of flow passages of compressor (fouling)
Inadvertent loss of speed
Instrument or control valve malfunction
Operator error
Misdistribution of load in parallel operation
Improper assembly of compressor (impeller overlap)
© 2006 Dresser-Rand
Restriction in Suction / DischargeRestriction in Suction / Discharge
© 2006 Dresser-Rand
Parallel OperationParallel OperationTypically, for parallel operation, the flow is not split evenly and one
section or compressor handles more flow than the other, but bothsections are required to make the same pressure ratio
Careful analysis of the pressure ratio curves is required to insure satisfactory operation and suitable overall range
“similar pressure ratio curves”• At the design flow, section (1) is much more flow than of section (2)
• If the total flow is reduced 10%, the compressor slows down to maintain the same pressure ratio
• The flow to each section is reduced 10% (dashed line) since the pressure ratio curves have a approximately the same rise
© 2006 Dresser-Rand
“different pressure ratio curves” (section 2 pressure ratio curve is steeper than section 1)• If the total flow is reduced 10% the compressor slows down to maintain pressure ratio• Section (1) reduces more than 10% ( about 12.5% - the dashed line) since its curve is shallower• Section (2) reduces less than 10% (about 5% - dashed line) since its curve is steeper
• The two sections are now operating at significantly different portions of the curve and are now handling a different percentage of the total flow than they were at the design point.
• Section (1) is nearing surge. Further reduction in flow would force section one into surge
• The difference in the curve shape results in a reduced overall range for parallel operation
© 2006 Dresser-Rand
Impeller Overlap with DiffuserImpeller Overlap with Diffuser
© 2006 Dresser-Rand
Impeller Overlap with DiffuserImpeller Overlap with Diffuser
Positive overlap
Limited
Nominal
Desired
Non Desirable
Limited
© 2006 Dresser-Rand
It is preferable that no impeller shall have negative overlap
The negative overlap is limited to 5% of the impeller tip
Impeller Overlap with DiffuserImpeller Overlap with Diffuser
© 2006 Dresser-Rand
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OverloadOverload
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© 2006 Dresser-Rand
Choke LimitChoke LimitChoke is the maximum flow that a centrifugal compressor
can handle at a given speed. At that point, the compressor is unable to produce any net overall pressure ratio.
The maximum flow region of the compressor performance curve is where the gas speeds approach Mach 1
Gas compression is no longer occurring in the compression channels. This region of the curve, as it becomes almost vertical at the choke limit, is also know as “Stonewall”
Stonewall is usually not detrimental to the compressor, it simply limits the maximum flow. If choke occurs at an off design condition, the maximum volume flow can be increased by increasing the rotational speed
© 2006 Dresser-Rand
Performance Curves Performance Curves –– Inlet Gas Inlet Gas Condition EffectsCondition Effects
© 2006 Dresser-Rand
Performance Curves Performance Curves –– Inlet Gas Inlet Gas Condition EffectsCondition Effects
© 2006 Dresser-Rand
Factors Affecting Compressor Factors Affecting Compressor Performance Performance
MW & Head - If MW increases, the head for a given ratio will decrease in direct proportion
Temp & Head - If the Ts increases, the head for a given ratio will increase in direct proportion
Zave & Head - If the average compressibility increases, the head will increase in direct proportion
N and Head - If speed increases, the head will increase in direct proportion
BHP and Head - If Head increases, the BHP will increase in direct proportion
Flow and Speed - If the speed increases, the flow will increase in direct proportion
© 2006 Dresser-Rand
Factors Affecting Compressor Factors Affecting Compressor Performance Performance
N & BHP - If the speed increases, the BHP will increase in proportion to the cube of the speed. (Because flow increases directly as speed and head increases as the square of the speed and BHP is the product of head X mass flow)
Density - The only thing a compressor impeller sees is inlet capacity. Thus to get more capacity out of an existing compressor it is necessary to change the density of the inlet by:
• decreasing the suction temperature• increasing the suction pressure • increasing the MW of the gas
© 2006 Dresser-Rand
Compressor Off Compressor Off -- Design Performance Design Performance
Performance curves for axial and centrifugal compressors are usually based on constant inlet conditions (Ps, Ts, MW). In actual service, these compressors rarely see these base curve conditions exactly
If the field inlet conditions deviate more then 5% from the curve inlet conditions then the field data can not be accurately plotted on the curve without converting the field data to curve conditions
To properly evaluate the compressor (running off design), the performance parameters shall be corrected to the design conditions
© 2006 Dresser-Rand
Allowable Variance for Inlet TZ / MW for Allowable Variance for Inlet TZ / MW for Acceptable Head Curve AccuracyAcceptable Head Curve Accuracy
© 2006 Dresser-Rand
Operation LimitationsOperation Limitations
Compressor
Driver
Power
Process
© 2006 Dresser-Rand
Compressor Operation IssuesCompressor Operation Issues--EfficiencyEfficiency DropDrop
Internal recycleUn-tuned Surge Control System Leakage via by-pass valve(s) in processCompressor operated out of “guaranteed performance envelope”Impeller & Diaphragm erosionFouling
© 2006 Dresser-Rand
Internal Recycle Internal Recycle –– Gap at the Gap at the diaphragm / guides splits diaphragm / guides splits
© 2006 Dresser-Rand
Internal Recycle Internal Recycle –– Gap at the Gap at the diaphragm / guides splits diaphragm / guides splits
© 2006 Dresser-Rand
Labyrinth LeakageLabyrinth Leakage
Eye Laby Leakage
Spacer Laby Leakage
Eye laby leakage is approx. 10 times
spacer laby leakage
Leakage proportional to:• ∆P• Clearance• Diameter•1 / (No.Laby Teeth)0.5
© 2006 Dresser-Rand
Internal Recycle Internal Recycle –– Labyrinth ClearanceLabyrinth Clearance
Process labyrinths can be plugged by wet particles in the gas flow
© 2006 Dresser-Rand
Internal Recycle Internal Recycle –– Labyrinth ClearanceLabyrinth Clearance
Impeller Cover
Shaft Spacer
© 2006 Dresser-Rand
Internal Recycle Internal Recycle –– Labyrinth ClearanceLabyrinth Clearance
Impeller Cover
© 2006 Dresser-Rand
PEEK Labyrinth PEEK Labyrinth
© 2006 Dresser-Rand
PEEK Physical Properties PEEK Physical Properties GRADE COEF.
THERMAL EXPNSION
(F)
TENSILE STRENGTH
(PSI)
ELONGATION (%)
SPECIFIC GRAVITY
Arlon CP 17 x 10 /-6 11,080 2.0 1.45 Torlon 4340
18.8 12,900 6.6 1.44
Fluorosint 500
19.4 1,100 10.0 2.32
© 2006 Dresser-Rand
UnUn-- tuned Surge Control Systemtuned Surge Control System
Recycle valve shall be calibrated at every planned S/D
• fast opening ( < 1 sec)
• total travel 0-100 %; 4 – 20 mA
• mechanical stop to coincide with 100 % close
Valve positioner shall match the command
FT instrument shall be calibrated at every planned S/D
Flow calculation block – correct constants, correct range
© 2006 Dresser-Rand
FoulingFouling
… is the deposit and the non –uniform accumulation of debris in the gas
Occurs due to carry over of liquids and debris from the inlet suction scrubber
Polymerization may occur in wet gas and cracked gas compressors applications if the temperature exceeds the critical point beyond the polymerization process occurs (235 F)
Fouling build up occurs usually on the impeller hub and shroud. There is also a build up on the blades ( on the pressure side)
© 2006 Dresser-Rand
FoulingFouling
1st stage impeller – hard depositsIGV partially clogged
© 2006 Dresser-Rand
Fouling Effects Fouling Effects –– Charge Gas Charge Gas
3M7 – Eroded Sleeves
© 2006 Dresser-Rand
April 25 '99 NPC Thai Fouling 9Abrasive Scoring due to Fouling
Fouling EffectsFouling Effects
© 2006 Dresser-Rand
Fouling EffectsFouling Effects – Charge Gas
3M7 - Deterioration of stage clearances
© 2006 Dresser-Rand
Fouling Deposit CharacterizationFouling Deposit CharacterizationScientifically characterization of the fouling deposits can provide clear information about the actual cause(s) of the problem(s) . Key deposit characterization includes:
1) Elemental Analysis - Chemical Composition (C, H, O, N, S)
2) Electron Microscopy Morphology – Microstructure composition analysis components (asphaltene, oil, coke, and inorganic)
3) TGA (thermo gravimetric analyzer) - Thermal fractionation into components
4) EDS (x-ray) Electron Dispersive Spectroscopy - Inorganic elements
5) X-RAY Diffraction - Inorganic compounds
© 2006 Dresser-Rand
Techniques to Prevent FoulingTechniques to Prevent Fouling
Condition monitoring, both aerodynamic and mechanical parameters
Process control
Online solvent injection
Coatings of Impellers and Diaphragms
© 2006 Dresser-Rand
Fouling Fouling -- Condition Monitoring Condition Monitoring (aerodynamic and mechanical parameters)(aerodynamic and mechanical parameters)
Monitor and trend the information regarding process conditions
• MW• Pressure• Temperature
Vibration monitoring• On line system• Off line system
© 2006 Dresser-Rand
Condition Monitoring Condition Monitoring
( )( )sd
sdp TT
PPkk
loglog1⋅
−=η
K – isentropic coefficient;Cp , Cv – specific heat at constant pressure / volume
Calculate and trend the compressor polytrophic efficiency using the reference point (i.e. after overhaul, revamp)
© 2006 Dresser-Rand
Condition Monitoring Condition Monitoring –– DR RECON DR RECON Online System Online System
© 2006 Dresser-Rand
Fouling Fouling -- Process ControlProcess Control
Accurate control of process conditions can prevent fouling ( for applications where polymers can be formed)
Temperature control is the most important factor for preventing polymer formations (i.e. Ethylene cracked gas, Fluid catalytic cracker off-gas FSS)
Critical temperature above fouling occurs varies with each process, compressor, application
Monitoring of process is required to establish the temperature threshold for each case
© 2006 Dresser-Rand
Fouling Fouling –– Online Fluid InjectionOnline Fluid Injection
.. injecting a small amount of solvent to reduce the friction coefficient of the blade and impeller surface (maintain the surface wet) thus preventing the fouling to build up on the surface
The injection shall be done from the start (new equipment / overhauled) , if not the fouling deposit could be dislodged and moved downstream (blockage)
Injection objective is to prevent fouling accumulations, not to provide on line cleaning of the impeller / blade
Non continuous solvent injection program will allow the impeller / blade to dry and promote fouling
© 2006 Dresser-Rand
Fouling Fouling –– Online Fluid InjectionOnline Fluid Injection
Critical factors that ensure fouling will not form:• Type of injection spray nozzles• Location of the spray nozzles• Selection of solvent
Solvent vapor pressure and internal comp temperatures is necessary to determine if stage or section solvent injection is applicableTypically amount of solvent injection is 1-2 % of
total mass flow. Excessive injection could erode leading edge blade tips, causing impeller fatigue
© 2006 Dresser-Rand
Online Fluid InjectionOnline Fluid InjectionSolvent injection:
• Purpose is to maintain a wet surface to prevent fouling materialsticking (typically Naphtha based solvent)• Injected at suction pipe of each section (Spool piece)• Injected at compressor return bends regardless gas temperature• 0.5 to 1.0% of total gas weight flow at each section is effective, but not exceed 3% of total gas weight flow
H2O injection:• Purpose is to reduce gas temperature ( by evaporation of water)• Injected at return bends where discharge gas temperature is high• Demi water (boiler feed water), with low oxygen content is recommended. Filters to be installed at upstream of spray nozzle to prevent clogging
© 2006 Dresser-Rand
Fluid Injection at Suction NozzleFluid Injection at Suction Nozzle
© 2006 Dresser-Rand
Fluid Injection at Return BendFluid Injection at Return Bend
© 2006 Dresser-Rand
Online Fluid InjectionOnline Fluid Injection
H2OTank
SolventInjection
Tank(Optional)
F
PG
Flowmeter
Pressure Gauge
Valve
Water Injection Nozzle
Optional Solvent Injection Nozzle
Water Injection Connecting Piping (By Customer)
Optional Solvent Injection Connecting Piping (By Customer)
BFW Pump (By Customer)
>20 kg/cm2
BFW PUMP
4M7-6Sect 1 Sect 2
Stg1
Stg2
Stg3
Stg1
Stg2
Stg3
“A”
“A”
“B” “B”
FPG
FPG
FPG
FPG
FPG
FPG
FPG
FPG
Sect 3 Sect 42M9-7
Stg1
Stg2
Stg3
Stg1
Stg2
Stg3
Stg4
FPG
FPG
FPG
FPG
FPG
FPG
FPG
PGF
PGF
© 2006 Dresser-Rand
Coatings Coatings -- Purpose Purpose
Prevent the base metal from external attackProtect the blades against oxidation, corrosion, and
cracking problemsExtend the life of the impeller (protect the blades by being
sacrificial by allowing coating to be restripped and recoated)Improve surface smoothness in order to reduce:• friction in lieu of solvent injection • erosion on compressor blades
© 2006 Dresser-Rand
Engineered Coatings Engineered Coatings –– ““Cold CoatingsCold Coatings””
a) Protection • Corrosion • Fouling• Erosion
b) Improved Operation • Smoother Surface Finish
• Improved Resistance to Fouling
• Improved Efficiency
• Improved Reliability
…. A Sacrificial Barrier Coating System with a Base
Coat and Multiple Topcoats
Benefits:
© 2006 Dresser-Rand
DD--R Corrosion / Antifoulant CoatingR Corrosion / Antifoulant CoatingSystem EECSystem EEC--C1C1
Hard Top Seal CoatHard Top Seal Coat
Sacrificial Base CoatSacrificial Base Coat
© 2006 Dresser-Rand
DD--R AntiR Anti--foulantfoulant Coating System Coating System EECEEC--A2 &A3A2 &A3
PTFE Top Coat
Sacrificial Base Coat
Barrier Coat
© 2006 Dresser-Rand
EEC EEC -- A3A3
EEC EEC -- A2A2
AntiAnti--Foulant CoatingFoulant Coating
© 2006 Dresser-Rand
Engineered Coatings Engineered Coatings –– Thermal Thermal CoatingsCoatings
• Protection • Wear • Erosion
• Improved Wear Characteristics
• Improved Reliability
• Dimensional Restoration
A metallic particle spray overlay applied by a High Velocity Oxy Fuel (HVOF) Process
Benefits:
© 2006 Dresser-Rand
Engineered Coatings Engineered Coatings –– Thermal Thermal CoatingsCoatings
• Protection • Wear • Erosion
• Improved Wear Characteristics
• Improved Reliability
• Dimensional Restoration
A metallic particle spray overlay applied by a High Velocity Oxy Fuel (HVOF) Process
Benefits:
© 2006 Dresser-Rand
ImpellersImpellersRotor ShaftsRotor Shafts
HVOF Applied EEC HVOF Applied EEC -- TC CoatingsTC Coatings
Piston RodsPiston Rods
© 2006 Dresser-Rand
Coatings Coatings -- SermaLon® Coating
The SermaLon coating system consists of:
• Al-filled chromate/phosphate bond coat;
• Intermediate high temperature polymeric inhibitive coating
• PTFE impregnated topcoat (provides a barrier against corrosion and excellent resistance to fouling)
The coating system provides excellent protection to 403 and 410stainless substrates when exposed to corrosive steam conditions or low pH wet chloride environments
© 2006 Dresser-Rand
Coatings Coatings -- SermaLon® Coating
AdvantagesSmooth surface finish and PTFE impregnated
topcoat contribute to performance recovery and reduced fouling rate
Excellent bond strength
High resistance to corrosion fatigue
ApplicationsCentrifugal compressors exposed to
wet chlorides or excessive fouling
Steam turbine components exposed to corrosive steam;
© 2006 Dresser-Rand