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

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 2

Sulfur Recovery Unit Steam Reheater Reaction Furnace Converter with WHB Acid Gas Feed to Burner Condenser Air Blower S S To Tail Gas Cleanup Unit Condenser Condenser S S 3

Modified Claus Process Key Reactions H 2 S + 3/2 O 2 → SO 2 + H 2 O (Combustion Reaction) 2H 2 S + SO 2 ↔ 3S + 2H 2 O (Claus Reaction) ____________________________________________ 3H 2 S + 3/2 O 2 ↔ 3S + 3H 2 O (Overall Reaction) 3H 2 S + 3/2 O 2 + 5.6 N 2 ↔ 3S + 3H 2 O + 5.6 N 2 Nitrogen bottlenecks the SRU !! 4

Why Oxygen Enrichment Increases SRU Capacity Oxygen 20.9 (Air) 25 50 100 Enrichment (%) Acid Gas 100 113 170 226 (kmol/h) Oxygen 50 57 85 113 (kmol/h) N2+Ar (kmol/h) 189 169 84 0 Total Flow to Reaction 339 339 339 339 Furnace (kmol/h) Total Flow to 292 284 259 232 TGCU (kmol/h) Total flow constant; Acid gas flow increases as O 2 % increases Approximately 0.9 tons of oxygen per ton of extra Sulphur production 5

OXYGEN ENRICHMENT (CH 4 , AIR SYSTEM) Time, Temperature, Turbulence 4 1 RELATIVE FLUE GAS VOLUME 0.9 3.5 RELATIVE RESIDENCE TIME 0.8 Residence time 3 0.7 2.5 0.6 2 0.5 0.4 Flue gas volume 1.5 0.3 1 0.2 0.5 0.1 0 0 21 30 40 50 60 70 80 90 100 OXYGEN ENRICHMENT % 6

SRU: Three Proven Technologies for Oxygen Enrichment Enrichment Capacity Combustion Technology Level Increase Air % O2 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 7

SRU Capacity Increase with Oxygen Enrichment 180 92% H 2 S Low Level Enrichment 160 % Capacity Increase Mid Level Enrichment 140 Temperature Moderation 120 70% H 2 S .Technologies 100 50% H 2 S 80 60 35% H 2 S 40 20 0 20 30 40 50 60 70 80 90 100 % Oxygen 8

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 9

Mega Size Plants Smaller equipment means:  Easier transportation  Greater number of potential fabricators / suppliers  Lower overall project cost  Shorter overall project schedule 10 10

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 H 2 S in the TGCU amine absorber lead to lower H 2 S content in absorber vent stream and hence lower SO 2 emissions  Much smaller vent gas stream (less N 2 ) from the absorber to the incinerator leads to less fuel gas usage and lower CO 2 emissions 11

Oxygen Enrichment Delivers Flexibility Refinery in USA -- Midwest 2500 19 20 11 Air (Nm 3 /h) 12 2000 13 Case8 Air Flow Rate 14 18 9 7 4 5 16 10 15 6 1500 17 33 A 30 Sulphur (LTPD) 11 14 13 20 19 S 5 Low Air 25 4 12 Flow B Case8 6 7 15 18 9 17 16 20 10 15 20 21 22 23 24 25 26 27 28 Oxygen Enrichment % 12

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 O 2 )  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 13

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 operating 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. 14

Process Gas Combustion Air Acid Gas STANDARD CLAUS PLANT Natural Gas 15

Process Gas Acid Gas LOW LEVEL O2 Natural ENRICHMENT Gas 16

Process Gas Natural Mid Level Gas Enrichment 17

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 N 2  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 18

Air Acid Gas NG O 2 19

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 20

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 21

HSE Considerations • Handling Pure Oxygen • Low pressure • Adiabatic temperature • System hygiene • Adiabatic Compression Concerns Reference Documents • Compressed Gas Association • Local regulations • Vendor guidelines 22

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 23

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 24

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 25

Backup Slides 26

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 N 2 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 27

Oxygen Supply Options 28

LOX Supply Tank and Delivery Truck 29

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