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Ethylene Unit Cracked Gas Compressor Case Studies on Fouling Visagaran Visvalingam - Presenter Cyron Anthony Soyza Sew Nyit Tong Karl Kolmetz

Ethylene Cracked Gas Compressor - Kolmetz.comkolmetz.com/pdf/articles/Cracked-Gas-Compressor.pdf · Identification of Turbine Fouling? ... Compressor System Flow Diagram Cracked Gas

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Page 1: Ethylene Cracked Gas Compressor - Kolmetz.comkolmetz.com/pdf/articles/Cracked-Gas-Compressor.pdf · Identification of Turbine Fouling? ... Compressor System Flow Diagram Cracked Gas

Ethylene Unit Cracked Gas CompressorCase Studies on Fouling

Visagaran Visvalingam - Presenter

Cyron Anthony Soyza

Sew Nyit Tong

Karl Kolmetz

Page 2: Ethylene Cracked Gas Compressor - Kolmetz.comkolmetz.com/pdf/articles/Cracked-Gas-Compressor.pdf · Identification of Turbine Fouling? ... Compressor System Flow Diagram Cracked Gas

Outlines

? Overview of Equipment and Setup

? CGC Fouling Experiences

? Identification of Turbine Fouling

? Impacts of Compressor-Turbine fouling

? Turnaround Inspections

? Countermeasures for Fouling Control

? Future Improvements

? Conclusions

Page 3: Ethylene Cracked Gas Compressor - Kolmetz.comkolmetz.com/pdf/articles/Cracked-Gas-Compressor.pdf · Identification of Turbine Fouling? ... Compressor System Flow Diagram Cracked Gas

Overview of Equipment & Setup

• CGC is a five stages centrifugal compressor

• Caustic wash and drying are facilitated between 4th

and 5th stage

• 5th stage is a heat pump for DeC3 system where C4

and heavier are removed

• CGC is driven by a SHP steam turbine

• Turbine extracts HP steam while condensing is

controlled by CGC power demand

Page 4: Ethylene Cracked Gas Compressor - Kolmetz.comkolmetz.com/pdf/articles/Cracked-Gas-Compressor.pdf · Identification of Turbine Fouling? ... Compressor System Flow Diagram Cracked Gas

Compressor System Flow Diagram

Cracked Gas

Caustic& Dryers

Stage 1 Stage 2 Stage 3 Stage 4

Stage 5

ToRecoverySection

HP DeC3

Acetylene Converters

Wash Oils

Page 5: Ethylene Cracked Gas Compressor - Kolmetz.comkolmetz.com/pdf/articles/Cracked-Gas-Compressor.pdf · Identification of Turbine Fouling? ... Compressor System Flow Diagram Cracked Gas

Diffusers

BalanceLine

Wheels

Inlet Vanes

Compressor Overview

Page 6: Ethylene Cracked Gas Compressor - Kolmetz.comkolmetz.com/pdf/articles/Cracked-Gas-Compressor.pdf · Identification of Turbine Fouling? ... Compressor System Flow Diagram Cracked Gas

Fouling Phenomenon - What,Why and How

• Organic : Free radicalmechanism catalyzed byperoxides, transition metals andheat

• Inorganic : Quench watercarryover

• Organic or inorganic depositsdehydrogenate over timeleaving behind

InitiateInitiate

PropagatePropagate

TerminateTerminate

R-H

• R • H

• ROO

heat

O2

ROOH + •R

R-H

•R•R +

Page 7: Ethylene Cracked Gas Compressor - Kolmetz.comkolmetz.com/pdf/articles/Cracked-Gas-Compressor.pdf · Identification of Turbine Fouling? ... Compressor System Flow Diagram Cracked Gas

CGC Fouling Experiences

£ Polytropic efficiencies dropped

£ Discharge temperatures increased

£ Inter-cooler pressure drops increased

£ Governor valve opening maximum

£ Turbine steam rate increased

£ Max continuos speed not sustainable

Page 8: Ethylene Cracked Gas Compressor - Kolmetz.comkolmetz.com/pdf/articles/Cracked-Gas-Compressor.pdf · Identification of Turbine Fouling? ... Compressor System Flow Diagram Cracked Gas

CGC Polytropic Efficiency

50

55

60

65

70

75

80

85

90

23/4/9628/6/9625/11/9630/4/9729/9/97

23/12/9721/5/9816/9/9805/12/9823/3/9916/07/9907/10/9925/12/9902/01/0006/03/0003/05/0010/07/0007/09/0004/11/0012/12/0005/01/01

Eff

icie

ncy

(%)

2nd stg Polly. Eff 3rd stg Polly. Eff 4th stg Polly. Eff 5th stg Polly. Eff

AFTER TURNAROUND

96

AFTER TURNAROUND

99

TURNAROUND 2001

Page 9: Ethylene Cracked Gas Compressor - Kolmetz.comkolmetz.com/pdf/articles/Cracked-Gas-Compressor.pdf · Identification of Turbine Fouling? ... Compressor System Flow Diagram Cracked Gas

Compressor Delta T

30

35

40

45

50

55

60

65

70

23/4

/96

28/6

/96

25/1

1/96

30/4

/97

29/9

/97

23/1

2/97

21/5

/98

16/9

/98

05/1

2/98

23/3

/99

16/0

7/99

07/1

0/99

25/1

2/99

02/0

1/00

06/0

3/00

03/0

5/00

10/0

7/00

07/0

9/00

04/1

1/00

Stage 1 delta T Stage 2 delta T Stage 3 delta T Stage 4 delta T

AFTER TURNAROUND

96

AFTER TURNAROUND

99TURNAROUND

2001

Page 10: Ethylene Cracked Gas Compressor - Kolmetz.comkolmetz.com/pdf/articles/Cracked-Gas-Compressor.pdf · Identification of Turbine Fouling? ... Compressor System Flow Diagram Cracked Gas

Identification of Turbine Fouling

? Unable to maintain speed at max steam flow

? HP and LP valve fully open

? Backpressure from LP turbine

HPValve

SHP

LPValve

P1 P2

HP SteamExtraction

ExhaustSteam

HP Casing LP Casing

Page 11: Ethylene Cracked Gas Compressor - Kolmetz.comkolmetz.com/pdf/articles/Cracked-Gas-Compressor.pdf · Identification of Turbine Fouling? ... Compressor System Flow Diagram Cracked Gas

Causes of Turbine Fouling

• BFW quality upset

– High Sodium / Silica due to capacity overrun orimproper regeneration of demin train

• Water Carry-over

– Steam drum level control high

• Steam contamination

– Attemporating water

high in sodium or silica

Water level

Page 12: Ethylene Cracked Gas Compressor - Kolmetz.comkolmetz.com/pdf/articles/Cracked-Gas-Compressor.pdf · Identification of Turbine Fouling? ... Compressor System Flow Diagram Cracked Gas

Impacts of Compressor-TurbineFouling

£ Throughput limited due to maximum driver governorvalve opening

£ Increased suction pressure

£ Energy inefficient due to higher steam rate

£ Short run length, 3 years down for cleaning

Page 13: Ethylene Cracked Gas Compressor - Kolmetz.comkolmetz.com/pdf/articles/Cracked-Gas-Compressor.pdf · Identification of Turbine Fouling? ... Compressor System Flow Diagram Cracked Gas

Turnaround Inspections

• Inspection done during TA99 and TA 2001

• 1st and 5th stage - relatively clean

• 2nd, 3rd & 4th stage - heavily fouled

• Polymer deposits and most samples were organic

component

• Inter-coolers fouled with polymers and tars

• Discharge piping layered with polymer

Page 14: Ethylene Cracked Gas Compressor - Kolmetz.comkolmetz.com/pdf/articles/Cracked-Gas-Compressor.pdf · Identification of Turbine Fouling? ... Compressor System Flow Diagram Cracked Gas

CGC Inspection- TA99 & TA2001

Summary of the Inspection Findings

Suct/Dischpiping

Impeller/Diffuser

Volute

1st stage

2nd stage

3rd stage

4th stage

5th stage

Turbine

Page 15: Ethylene Cracked Gas Compressor - Kolmetz.comkolmetz.com/pdf/articles/Cracked-Gas-Compressor.pdf · Identification of Turbine Fouling? ... Compressor System Flow Diagram Cracked Gas

1st Discharge1st Discharge 2nd Discharge2nd Discharge 4th Discharge4th Discharge3rd Discharge3rd Discharge

1st to 4th Stage Discharge Condition during Turnaround 2000/011st to 4th Stage Discharge Condition during Turnaround 2000/01

Page 16: Ethylene Cracked Gas Compressor - Kolmetz.comkolmetz.com/pdf/articles/Cracked-Gas-Compressor.pdf · Identification of Turbine Fouling? ... Compressor System Flow Diagram Cracked Gas

RotorRotor CasingCasing

Page 17: Ethylene Cracked Gas Compressor - Kolmetz.comkolmetz.com/pdf/articles/Cracked-Gas-Compressor.pdf · Identification of Turbine Fouling? ... Compressor System Flow Diagram Cracked Gas

2nd stage intercooler bundle Bundle entrance

Polymer laced inlet pipeline Inlet to intercooler

Page 18: Ethylene Cracked Gas Compressor - Kolmetz.comkolmetz.com/pdf/articles/Cracked-Gas-Compressor.pdf · Identification of Turbine Fouling? ... Compressor System Flow Diagram Cracked Gas

Turnaround inspections - CGC Turbine

Page 19: Ethylene Cracked Gas Compressor - Kolmetz.comkolmetz.com/pdf/articles/Cracked-Gas-Compressor.pdf · Identification of Turbine Fouling? ... Compressor System Flow Diagram Cracked Gas

Countermeasures for Fouling Control• Compressor wash oil review

¤ Feed points available at the suction piping¤ Injection spray atomizers enhance distribution¤ Increased wash oil injection rate to 3-4% vol.¤ Quality monitoring - existent gums¤ Quantity monitoring - dP

• Antifoulant Injection

¤ Trial run at the 4th stage - worst case

• Improved BFW quality¤ Proper Demin regeneration and lower steam drum level

Page 20: Ethylene Cracked Gas Compressor - Kolmetz.comkolmetz.com/pdf/articles/Cracked-Gas-Compressor.pdf · Identification of Turbine Fouling? ... Compressor System Flow Diagram Cracked Gas

Compressor Wash Oil Review

? 1st to 3rd stage - HPG + C5

? 4th stage - HPG

? Specific gravity - 0.77-0.80

? Aromatic content - 65 %

? Existent gums - < 5mg/100ml

? Distillation D-86

– IBP - 70 oC

– End point - 185 oC

Page 21: Ethylene Cracked Gas Compressor - Kolmetz.comkolmetz.com/pdf/articles/Cracked-Gas-Compressor.pdf · Identification of Turbine Fouling? ... Compressor System Flow Diagram Cracked Gas

Anti-foulant Injection

• Trail run at 4th stage

• Start of run - 9 May 02

• Co-injection with the existing wash oil

• Injection rate at 2-5 ppm by weight

• Monitoring parameters :− Polytropic Efficiency− Suction / Discharge Temperatures− Pressure Drop Across Inter-cooler− Steam Consumption− Vibrations

Page 22: Ethylene Cracked Gas Compressor - Kolmetz.comkolmetz.com/pdf/articles/Cracked-Gas-Compressor.pdf · Identification of Turbine Fouling? ... Compressor System Flow Diagram Cracked Gas

Antifoulant Trial Run

Cracked Gas

Caustic& Dryers

Stage 1 Stage 2 Stage 3 Stage 4

Stage 5To

RecoverySection

HP DeC3

Acetylene Converters

Wash Oils

Antifoulant : 2-5ppm wt based on the4th stage charge rate

Page 23: Ethylene Cracked Gas Compressor - Kolmetz.comkolmetz.com/pdf/articles/Cracked-Gas-Compressor.pdf · Identification of Turbine Fouling? ... Compressor System Flow Diagram Cracked Gas

• Polytropic efficiency improved - 4-5%

• Comp discharge temperature reduced - 3-4oC

• Delta T reduced

• Pressure drop across inter-cooler maintained

• Vibration normal

Antifoulant Trial Run Findings

Page 24: Ethylene Cracked Gas Compressor - Kolmetz.comkolmetz.com/pdf/articles/Cracked-Gas-Compressor.pdf · Identification of Turbine Fouling? ... Compressor System Flow Diagram Cracked Gas

4th Stage Polytropic Efficiency and Delta T

65

66

67

68

69

70

71

72

73

74

75

76

05-0

1-02

15-0

1-02

25-0

1-02

04-0

2-02

14-0

2-02

24-0

2-02

06-0

3-02

16-0

3-02

26-0

3-02

05-0

4-02

15-0

4-02

25-0

4-02

05-0

5-02

15-0

5-02

25-0

5-02

04-0

6-02

14-0

6-02

4th

Sta

ge P

olyt

ropi

c E

ffici

ency

, %

51

52

53

54

55

56

57

58

59

60

61

Com

pres

sor D

elta

T, d

egC

Efficiency (%) DT

Dosage 2ppm Dosage 3-4 ppm

Page 25: Ethylene Cracked Gas Compressor - Kolmetz.comkolmetz.com/pdf/articles/Cracked-Gas-Compressor.pdf · Identification of Turbine Fouling? ... Compressor System Flow Diagram Cracked Gas

4th Stage Polytropic Efficiency and Delta T

C-300 Efficiency

60

62

64

66

68

70

72

74

76

78

80

31-Mar-02

05-Apr-02

10-Apr-02

15-Apr-02

20-Apr-02

25-Apr-02

30-Apr-02

05-May-02

10-May-02

15-May-02

20-May-02

25-May-02

30-May-02

04-Jun-02

09-Jun-02

14-Jun-02

19-Jun-02

24-Jun-02

Eff

, %

2nd stage

4th stage

Ave eff = 1st to 3rd stage

Page 26: Ethylene Cracked Gas Compressor - Kolmetz.comkolmetz.com/pdf/articles/Cracked-Gas-Compressor.pdf · Identification of Turbine Fouling? ... Compressor System Flow Diagram Cracked Gas

Future Improvements� Wash oil quality

– C8+ High aromatics, low gums & higher FBP

– Intermittent or Continuos - 0.5% wg

– High volume flush - 2% wg

� Wash oil and Antifoulant injection to casing– Revamp or TA modification

� Wash water injection– max 1% throughput to minimize rotor erosion

� Inter-coolers– Antifoulant injection facilities for online cleaning

� High efficiency 3D impeller blades (new service)– More efficient and larger gas passage

Page 27: Ethylene Cracked Gas Compressor - Kolmetz.comkolmetz.com/pdf/articles/Cracked-Gas-Compressor.pdf · Identification of Turbine Fouling? ... Compressor System Flow Diagram Cracked Gas

Conclusions

? A review of equipment and maintenance records areessential to each producer

? Part of this review should include turbine andcompressor fouling

? Adequate wash oil selection and antifoulant injectionenables cracker extension of cracked gas compressorrun lengths by reducing the amount of polymerfouling.

? Any review should also include future optimizations

Page 28: Ethylene Cracked Gas Compressor - Kolmetz.comkolmetz.com/pdf/articles/Cracked-Gas-Compressor.pdf · Identification of Turbine Fouling? ... Compressor System Flow Diagram Cracked Gas

Thank You

Q & A