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Page 1: Waste Heat Boilers and Sulphur Condensers in the Sulphur ... Heat Boilers and... · Waste Heat Boilers and Sulphur Condensers in the Su lphur Process Industry: Facing the Large Plant

Waste Heat Boilers and Sulphur Condensers in the Sulphur Process Industry

Facing the Large Capacity Trend

David K. StevensMark Tonjes

KPS Technology & Engineering LLC

Gennaro Natali-SoraGiovanni Manenti

FBM Hudson Italiana SpA

October 2008

Sulphur 2008 International Conference and Exhibition

Page 2: Waste Heat Boilers and Sulphur Condensers in the Sulphur ... Heat Boilers and... · Waste Heat Boilers and Sulphur Condensers in the Su lphur Process Industry: Facing the Large Plant

Waste Heat Boilers and Sulphur Condensers in the Sulphur Process Industry: Facing the Large Plant Capacity Trend

Large is awesome…

…and, likely, cost effective.

Page 3: Waste Heat Boilers and Sulphur Condensers in the Sulphur ... Heat Boilers and... · Waste Heat Boilers and Sulphur Condensers in the Su lphur Process Industry: Facing the Large Plant

Waste Heat Boilers and Sulphur Condensers in the Sulphur Process Industry: Facing the Large Plant Capacity Trend

Presentation Overview

1 Sulphur Plant Capacity Trends

2 Design Basis for Realizing SR and SA Waste Heat Boilers and Condensers

3 Conclusions

Page 4: Waste Heat Boilers and Sulphur Condensers in the Sulphur ... Heat Boilers and... · Waste Heat Boilers and Sulphur Condensers in the Su lphur Process Industry: Facing the Large Plant

Waste Heat Boilers and Sulphur Condensers in the Sulphur Process Industry: Facing the Large Plant Capacity Trend

1.1 General Trend

While it is impossible today to predict with certainty the future of Oil&Gas demand and the resultant quantity of the recovered sulfur, it is seen that there is a clear trend of increasing “sourness”of available Oil&Gas reserves and that the resultant size of the sulfur recovery (SR) units is increasing.

Sulphuric acid (SA) plants are not excluded from this rise in dimensions, due to an economy of scale.

Page 5: Waste Heat Boilers and Sulphur Condensers in the Sulphur ... Heat Boilers and... · Waste Heat Boilers and Sulphur Condensers in the Su lphur Process Industry: Facing the Large Plant

Waste Heat Boilers and Sulphur Condensers in the Sulphur Process Industry: Facing the Large Plant Capacity Trend

1.2 Plant Capacity Trends

• More sour reserves are being considered

• Sulfur recovery and acid gas injection (AGI) economics and technical limitations of AGI is complex

• Average throughput of new facilities is increasing to take advantage of economies of scale

• Energy and environmental issues boot economy of scale

Page 6: Waste Heat Boilers and Sulphur Condensers in the Sulphur ... Heat Boilers and... · Waste Heat Boilers and Sulphur Condensers in the Su lphur Process Industry: Facing the Large Plant

Waste Heat Boilers and Sulphur Condensers in the Sulphur Process Industry: Facing the Large Plant Capacity Trend

1.3 Calculated Effect of Processing Sour Water Stripper Offgas on Claus / Tail Gas Capacity at Constant Air Demand

0

20

40

60

80

100

0

20

40

60

80

100

0 5 10 15 20 25

LTPD

Sul

fur

plus

ETP

D N

H3

LTPD

Sul

fur

Prod

uced

NH3% (vol) in Total Amine Acid Gas plus SWS Offgas

Page 7: Waste Heat Boilers and Sulphur Condensers in the Sulphur ... Heat Boilers and... · Waste Heat Boilers and Sulphur Condensers in the Su lphur Process Industry: Facing the Large Plant

Waste Heat Boilers and Sulphur Condensers in the Sulphur Process Industry: Facing the Large Plant Capacity Trend

1.4 New Plant Construction – Size Impacts

0

50

100

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350

400

0 5 10 15 20 25

ETPD

Sul

fur

% NH3 (vol) in Total Amine Acid Gas plus SWS Offgas

Amine Acid Gas H2S

Page 8: Waste Heat Boilers and Sulphur Condensers in the Sulphur ... Heat Boilers and... · Waste Heat Boilers and Sulphur Condensers in the Su lphur Process Industry: Facing the Large Plant

Waste Heat Boilers and Sulphur Condensers in the Sulphur Process Industry: Facing the Large Plant Capacity Trend

1.5 Conceptual Thinking About Size & Capacity

• WHB and SC are the most critical items with respect to increase of plant size

• Absolutely minimize the number of equipment (merge 2 items in parallel into a large one)

• Move from two kettles to one large waste heat boiler and steam drum package

• Utilize oxygen enrichment of combustion air to replace the inert nitrogen in air

• Increase the gas operating pressure profile

Page 9: Waste Heat Boilers and Sulphur Condensers in the Sulphur ... Heat Boilers and... · Waste Heat Boilers and Sulphur Condensers in the Su lphur Process Industry: Facing the Large Plant

Waste Heat Boilers and Sulphur Condensers in the Sulphur Process Industry: Facing the Large Plant Capacity Trend

Presentation Overview

1 Sulphur Plant Capacity Trends

2 Design Basis for Realizing SR and SA Waste Heat Boilers and Condensers

3 Conclusions

Page 10: Waste Heat Boilers and Sulphur Condensers in the Sulphur ... Heat Boilers and... · Waste Heat Boilers and Sulphur Condensers in the Su lphur Process Industry: Facing the Large Plant

Waste Heat Boilers and Sulphur Condensers in the Sulphur Process Industry: Facing the Large Plant Capacity Trend

2.1 Simplified SRU/TGTU Flowsheet

Page 11: Waste Heat Boilers and Sulphur Condensers in the Sulphur ... Heat Boilers and... · Waste Heat Boilers and Sulphur Condensers in the Su lphur Process Industry: Facing the Large Plant

Waste Heat Boilers and Sulphur Condensers in the Sulphur Process Industry: Facing the Large Plant Capacity Trend

Furnace WHB PackageSuperheater / Economizer

2.2 Simplified SA Flowsheet

Page 12: Waste Heat Boilers and Sulphur Condensers in the Sulphur ... Heat Boilers and... · Waste Heat Boilers and Sulphur Condensers in the Su lphur Process Industry: Facing the Large Plant

Waste Heat Boilers and Sulphur Condensers in the Sulphur Process Industry: Facing the Large Plant Capacity Trend

Current projects require SR and SA trains up to 350 t/h (1000 to 2000 tpd S1) of gas flow-rate and 4000 MTPD of productrespectively.

Relevant WHB’s typical sizes, with steam at 45 bar(g):• 450 tons + refractory

• 6000 ID

• 2600 tubes ( 63,5mm OD x 7500mm L )

2.3 Typical Large WHB Characteristics

Page 13: Waste Heat Boilers and Sulphur Condensers in the Sulphur ... Heat Boilers and... · Waste Heat Boilers and Sulphur Condensers in the Su lphur Process Industry: Facing the Large Plant

Waste Heat Boilers and Sulphur Condensers in the Sulphur Process Industry: Facing the Large Plant Capacity Trend

5500mm I.D. WHB…

Page 14: Waste Heat Boilers and Sulphur Condensers in the Sulphur ... Heat Boilers and... · Waste Heat Boilers and Sulphur Condensers in the Su lphur Process Industry: Facing the Large Plant

Waste Heat Boilers and Sulphur Condensers in the Sulphur Process Industry: Facing the Large Plant Capacity Trend

2.4 WHB Weight versus Shell Diameter

50

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550

2.0 3.0 4.0 5.0 6.0

Shell I.D. (m)

Del

iver

y W

eigh

t (r

efra

ctor

y in

clud

ed)

(ton

)

Page 15: Waste Heat Boilers and Sulphur Condensers in the Sulphur ... Heat Boilers and... · Waste Heat Boilers and Sulphur Condensers in the Su lphur Process Industry: Facing the Large Plant

Waste Heat Boilers and Sulphur Condensers in the Sulphur Process Industry: Facing the Large Plant Capacity Trend

• Critical heat flux (it decreases with tube bundle diameter)

• Differential elongation between the tube bundle and the shell

• Thermal load on tubes and design of the tubesheet

• Pressure drop tubeside

2.5 Design Considerations for a Safe Design

Page 16: Waste Heat Boilers and Sulphur Condensers in the Sulphur ... Heat Boilers and... · Waste Heat Boilers and Sulphur Condensers in the Su lphur Process Industry: Facing the Large Plant

Waste Heat Boilers and Sulphur Condensers in the Sulphur Process Industry: Facing the Large Plant Capacity Trend

2.6 Differential elongation between tubes and shell

• Average tube & shell wall temperatures are very close (∆ T = 15 to 20°C)

• Tube lengths up to 14m are not mechanically critical

• Pressure drop may be a limitation and actual lengths typically do not exceed 10m

Page 17: Waste Heat Boilers and Sulphur Condensers in the Sulphur ... Heat Boilers and... · Waste Heat Boilers and Sulphur Condensers in the Su lphur Process Industry: Facing the Large Plant

Waste Heat Boilers and Sulphur Condensers in the Sulphur Process Industry: Facing the Large Plant Capacity Trend

• This parameter must always be considered

• The controlling variables are:a) Design thermal flux at the boiler inletb) Thickness of the tubesc) Design water side fouling factor

• It is quite unusual for the tube wall temperature to limit the overall size of a boilers when the design flux is kept low due to the limit on the critical flux

2.7 Tube Wall Temperature

Page 18: Waste Heat Boilers and Sulphur Condensers in the Sulphur ... Heat Boilers and... · Waste Heat Boilers and Sulphur Condensers in the Su lphur Process Industry: Facing the Large Plant

Waste Heat Boilers and Sulphur Condensers in the Sulphur Process Industry: Facing the Large Plant Capacity Trend

2.8 Tubesheet Stress Analysis

Special calculations may be necessary for special (large dimensions).

Page 19: Waste Heat Boilers and Sulphur Condensers in the Sulphur ... Heat Boilers and... · Waste Heat Boilers and Sulphur Condensers in the Su lphur Process Industry: Facing the Large Plant

Waste Heat Boilers and Sulphur Condensers in the Sulphur Process Industry: Facing the Large Plant Capacity Trend

2.9 Tube Side Pressure Drop

• This process limitation has a significant impact on WHB and SC size

• Ferrules account for up to 30% of tubesidepressure drop depending on tube diameter

• Use cold drawn tubes

Page 20: Waste Heat Boilers and Sulphur Condensers in the Sulphur ... Heat Boilers and... · Waste Heat Boilers and Sulphur Condensers in the Su lphur Process Industry: Facing the Large Plant

Waste Heat Boilers and Sulphur Condensers in the Sulphur Process Industry: Facing the Large Plant Capacity Trend

2.10 Selection of Shell Plate Material

• Cost and availability of steam side shell material may be a practical limitation to optimum design

• With steam at 45 bar(g), SA516 Gr.70 is acceptable up to 6500 mm

• SA302 Gr.B is a cost efficient selection for larger diameters and higher steam pressures.

• ASME Section VIII Div 2 is also an option for some materials

Page 21: Waste Heat Boilers and Sulphur Condensers in the Sulphur ... Heat Boilers and... · Waste Heat Boilers and Sulphur Condensers in the Su lphur Process Industry: Facing the Large Plant

Waste Heat Boilers and Sulphur Condensers in the Sulphur Process Industry: Facing the Large Plant Capacity Trend

• Shell itself is not a limiting factor• Handling equipment and supports are essential • Tube-to-tubesheet joint longest duration operation • Local PWHT to be considered • Welded plate vs single plate • Forged external ring

2.11 Fabrication of large diameter bundles

Page 22: Waste Heat Boilers and Sulphur Condensers in the Sulphur ... Heat Boilers and... · Waste Heat Boilers and Sulphur Condensers in the Su lphur Process Industry: Facing the Large Plant

Waste Heat Boilers and Sulphur Condensers in the Sulphur Process Industry: Facing the Large Plant Capacity Trend

• Trial fit-up is a recommended practice in spite of size problems

• Temporary support structures always to be considered

• Modularised delivery remains a viable option for shops located on port areas

• Furnace-to-WHB weld and hydro-test done at workshop greatly speed-up erection at site. Always check WHB manufacturer capabilities

2.11 Trial Fit-up & Final Tests

Page 23: Waste Heat Boilers and Sulphur Condensers in the Sulphur ... Heat Boilers and... · Waste Heat Boilers and Sulphur Condensers in the Su lphur Process Industry: Facing the Large Plant

Waste Heat Boilers and Sulphur Condensers in the Sulphur Process Industry: Facing the Large Plant Capacity Trend

3 Conclusions

• Trends in sulphur plants require large Waste Heat Boilers and Sulphur Condensers

• Large equipment poses design and manufacturing issues

• These problems can be overcome, provided they are dealt with competence and experience

• Today, WHBs and Sulphur Condensers of 7m to 8m diameter can be safely manufactured and operated (shell-side pressure to be checked)

Page 24: Waste Heat Boilers and Sulphur Condensers in the Sulphur ... Heat Boilers and... · Waste Heat Boilers and Sulphur Condensers in the Su lphur Process Industry: Facing the Large Plant

Sulphur 2008 International Conference and Exhibition


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