Oxygen Enrichment of SRUs Theory, Benefits, Equipment, Utility - - PowerPoint PPT Presentation

Oxygen Enrichment of SRUs Theory, Benefits, Equipment, Utility & Safety Considerations

MESPON 2017 Abu Dhabi, UAE 15 -17 October 2017 Uday N. Parekh Elmo Nasato

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Outline

 Introduction “Oxygen Enrichment for your Burning Needs”  Oxygen Enrichment Theory  SRU Oxygen Enrichment Technologies  Benefits  Equipment, Utility & Safety Considerations  Implementation  Oxygen Supply Alternatives  Conclusion

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Sulfur Recovery Unit

Condenser S Condenser S To Tail Gas Cleanup Unit Air Blower Acid Gas Feed to Burner Reaction Furnace with WHB Steam Reheater Converter Condenser S S

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Modified Claus Process Key Reactions

H2S + 3/2 O2 → SO2 + H2O (Combustion Reaction) 2H2S + SO2 ↔ 3S + 2H2O (Claus Reaction) ____________________________________________ 3H2S + 3/2 O2 ↔ 3S + 3H2O (Overall Reaction) 3H2S + 3/2 O2 + 5.6 N2 ↔ 3S + 3H2O + 5.6 N2 Nitrogen bottlenecks the SRU !!

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Why Oxygen Enrichment Increases SRU Capacity

Oxygen Enrichment (%) 20.9 (Air) 25 50 100 Acid Gas (kmol/h) 100 113 170 226 Oxygen (kmol/h) 50 57 85 113 N2+Ar (kmol/h) 189 169 84 Total Flow to Reaction Furnace (kmol/h) 339 339 339 339 Total Flow to TGCU (kmol/h) 292 284 259 232 Total flow constant; Acid gas flow increases as O2% increases Approximately 0.9 tons of oxygen per ton of extra Sulphur production

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OXYGEN ENRICHMENT % RELATIVE FLUE GAS VOLUME 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 21 30 40 50 60 70 80 90 100 0.5 1 1.5 2 2.5 3 3.5 4 RELATIVE RESIDENCE TIME Residence time Flue gas volume

OXYGEN ENRICHMENT (CH4, AIR SYSTEM) Time, Temperature, Turbulence

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SRU: Three Proven Technologies for Oxygen Enrichment

Enrichment Level Capacity Increase Combustion Air % O2 Technology Low-Level 10-30% 21-28% Oxygen introduced via a custom designed diffuser Mid-Level 30-70% 28-45% Special Burner with a Dedicated Oxygen Port High-Level 60-150% 40-100% RF Temperature Moderation Technology COPE, SURE, OxyClaus Applicable to rich acid gas streams

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SRU Capacity Increase with Oxygen Enrichment

20 40 60 80 100 120 140 160 180 20 30 40 50 60 70 80 90 100 % Capacity Increase % Oxygen 92% H2S Low Level Enrichment Mid Level Enrichment Temperature Moderation .Technologies 70% H2S 50% H2S 35% H2S

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Benefits of SRU Oxygen Enrichment

 Capacity Increase and Full Redundancy  Capital Cost Savings (40% -90%)  OPEX – Power and Fuel Gas Savings  Operational Flexibility  Improved Conversion and Reduced Emissions  Operational Reliability / Ease – Hotter Flame – Adequate Temperature & Better Contaminant Destruction – Eliminate/reduce preheating & fuel gas co-firing  Quick Implementation  Compact Footprint  Proven Safety

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Smaller equipment means:

 Easier transportation  Greater number of potential fabricators / suppliers  Lower overall project cost  Shorter overall project schedule

Mega Size Plants

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SRU Oxygen Enrichment Benefits Lower Emissions

SRU impact  Improved overall sulfur recovery efficiency due to higher partial pressures and conversions in the SRU catalytic reactors – about 0.5% higher TGCU impact  Reduced flow rates and higher partial pressure of H2S in the TGCU amine absorber lead to lower H2S content in absorber vent stream and hence lower SO2 emissions  Much smaller vent gas stream (less N2) from the absorber to the incinerator leads to less fuel gas usage and lower CO2 emissions

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Oxygen Enrichment Delivers Flexibility

Refinery in USA -- Midwest

19 20 11 12 13 14 18 10 9 Case8 7 4 5 6 17 15 16 Air Flow Rate 13 14 12 10 9 Case8 18 19 20 17 15 16 11 7 4 5 6 A B S Low Air Flow 33 30 25 20 15 20 21 22 23 24 25 26 27 28 2500 2000 1500 Air (Nm3/h) Sulphur (LTPD) Oxygen Enrichment %

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Oxygen Enrichment Scenarios

 Tactical – Sour crude campaign – Sour feedstock (temporary) – Extend time to turnarounds – Increase processing capacity of on-stream SRUs during S/D of one or more other SRUs – Typically LOX supply (unless other uses for O2)  Strategic – New Complex -- Save capital by building fewer or smaller SRUs – Existing Complex -- Avoid building additional SRUs due to increased or sourer feedstock – Typically on-site supply – VSA or Cryo

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In the Customer’s own words Huajin Refinery, China

Summary: Oxygen enriched SRU operation has been successfully implemented in the Huajin refinery; this increased the sulphur processing capacity from 60 000 t/y to 95 000 t/y. Besides increased sulphur processing capacity, various benefits such as reduced emissions, increased sulphur recovery efficiency, improved impurity destruction, enhanced tail gas treating unit performance, reduced utility consumption and increased steam production have been

• realised. The Huajin oxygen enriched SRU system has been
• perating safely and smoothly since starting up in October

2012 and is the first oxygen enrichment process implemented in China.

• Z. Tang, Z. Nie, W.Huang, X. Jin, J. Wu, J. Wang and K.H. Chung – Liaoning Huajin Tongda

Chemicals, Gas 2015.

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STANDARD CLAUS PLANT

Natural Gas Acid Gas Combustion Air Process Gas

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Natural Gas Acid Gas Process Gas

LOW LEVEL O2 ENRICHMENT

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Process Gas

Natural Gas

Mid Level Enrichment

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Key Equipment Considerations for Oxygen Enrichment

 Dedicated Oxygen Introduction Path – Main Burner  Higher Temperatures in the Reaction Furnace  Greater Heat Duty in Waste Heat Boiler and First Condenser  Better Heat Transfer in WHB – More radiant heat transfer: more water, less N2  Higher Delta Temperature in Claus Converters  Higher Water Production and Removal in TGTU Quench – Increase in water is proportional to increase in S production  Better Performance in TGTU Amine Absorber

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Air Acid Gas NG O2

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Implementation

 Feasibility Study – Process Evaluation/ Simulation – Economics Evaluation  BDEP  Supply of Customized / Proprietary Equipment  Help Determine best mode of Oxygen Supply  Assistance in Detailed Design, Procurement and EPC stage  Collaboration on Hazops; Operator Safety Training  Start-up assistance; Performance Testing  Ongoing Support / Technical Advice

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Customer Main Installation Scope

 Concrete pad for oxygen supply system  Field pipe: – oxygen supply to Oxygen Flow Control System (OFCS) – OFCS to diffuser  Installation of diffuser: – If necessary, install attachment spool  Field electrical & instrumentation  Online oxygen analyzer and provide output signal to control panel

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• Handling Pure Oxygen
• Low pressure
• Adiabatic temperature
• System hygiene
• Adiabatic Compression Concerns

Reference Documents

• Compressed Gas Association
• Local regulations
• Vendor guidelines

HSE Considerations

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Safety -- Key Oxygen System Interlocks

 High Oxygen Enrichment Level – Calculated – Measured  High Oxygen Flow Rate  Low Oxygen Pressure or Temperature  Low Combustion Air Pressure and Flow  High Combustion Air Line Temperature  High RF Temperature  Loss of Electrical Power to OFCS  SRU Shut Down

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Conclusions

 SRU Oxygen Enrichment is a proven technology with wide benefits and broad commercial adoption.  Full range of SRU oxygen enrichment technologies for capacity increase from 10% to 150%.  Reliable operation since mid 80s of the COPE and SURE technologies.  Seamless expansion from LLE to HLE  Satisfied / happy operators worldwide -- testimonials  Dispel misconception that applicable only where O2 infrastructure already exists

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Selection Criteria for Optimum Mode of Oxygen Supply

 Size of requirement (average and peak demand)  Oxygen purity required  Oxygen use pattern  Need for co-product nitrogen  Other oxygen consuming applications within plant / nearby  Power availability and cost  Proximity of delivered oxygen source / pipeline  Requirement term

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Backup Slides

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Choosing the Right Oxygen Supply Mode

LOX VSA Cryo Pipeline Supply Features Flow Range T/D 0-50 50-150 100+ 100+ Price Range $/T 60-120 35-55 25-50 25-50 Commitment Low High High Medium Coproduct N2 No No Yes Maybe Time to Implement 1-2 Months 10-15 Months 12-18 Months 6-8 Months Location Limitations Yes No No Yes Application - Best Fit Flow Low Medium High High Use Pattern Variable Steady Steady Variable LOX = Liquid Oxygen VSA = Vacuum Swing Adsorption Cryo = Cryogenic Air Separation Plant Pipeline = Gas Piped in from Remote Air Separation Plant

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Oxygen Supply Options

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LOX Supply Tank and Delivery Truck

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Why Oxygen Enrichment Decreases SRU Emissions

Rich Acid Gas Feed (93.7% H2S) Air-Based Operation COPE Operation (65% O2) COPE vs Air-Based 100 LTPD 200 LTPD % Increase Comments Contained S in Feed, LTPD 100 200 100% SRU Tail Gas Flow, MSCFH 353 322

• 9%

Contained S in Tail Gas, LTPD 2.7 4.2 56% Feed Gas to TGCU Amine Absorber, MSCFH 257 104

• 60%

Feed to absorber 60% lower despite 2X capacity Absorber Off-Gas to Incinerator, MSCFH 255 98

• 62%

Feed to incinerator 62% lower despite 2X capacity H2S Level in Absorber Off-Gas, ppmv 80 80 0% Contained S in Gas to Incinerator, lb/hr 1.72 0.66

• 62%

SO2 Emissions from Incinerator Stack, TPY 15.05 5.78

• 62%

SO2 emissions 62% lower despite 2X capacity!

Greatly reduced flow rates in the TGCU result in a 80% reduction in unit SO2 emissions

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Example - Benefits of COPE for a Grassroots Sulfur Recovery Complex

Basis: 1,200 TPD total SRU capacity Air-Based Configuration: Four 400 TPD SRU and TGCU trains (one train is spare) Proposed COPE Configuration: Three COPE Phase II SRU and TGCU trains (sized approx 300 TPD air-based), each capable of a maximum capacity of 600 TPD

• More capacity with three COPE trains than four air-based trains!
• Normal operating mode would be operation in COPE Phase I mode
• Switch quickly to COPE Phase II operation on both operating

trains if one train goes down, still providing 1200 TPD capacity

Configuration SRU Capacity (TPD) Train 1 Train 2 Train 3 Train 4 Total Total - with one train down Air-Based 400 400 400 400 1600 1200 COPE Phase I 400 400 400 None 1200 Switch to COPE II COPE Phase II 600 600 600 None 1800 1200

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Air-based vs Grassroots COPE Capital, Operating Cost, Emissions Comparison

Four 400 TPD air- based SRUs & TGCUs Three 300 TPD air-based SRUs & TGCUs + ASU for O2 (and N2)

* +/- 25% USGC basis; all numbers are rough estimates

Capital Cost Base Base - $ 90 MM* Yearly Operating Cost Power (8c/kwh) Base Base + $1.1 MM Natural Gas($0.35/Nm3) Base Base - $3.0 MM - 0.4 MM Oxygen None + $ 3.2 MM Operations & Maint Base Base - $1.7 MM Emissions (tons/year) SO2 Base Base - 59.7 CO2 Base Base - 23,500

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Summary

An SRU configuration utilizing the COPE technology provides:  Very significant capital savings estimated at US $ 70 MM  Operating cost savings or cost neutral  Reductions in CO2 emissions  Reductions in SO2 emissions