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Opportunities and Challenges: Update on the WSACC Heat to Energy Project

Opportunities and Challenges: Update on the WSACC Heat to Energy Project. Thomas Hahn, PE (CH2M HILL) Coleman Keeter (WSACC) Angela Roberts, PE (CH2M HILL). Agenda. Background / Existing Facilities Need for Project Description of Project Features Imported Biosolids Handling Facility

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Opportunities and Challenges: Update on the WSACC Heat to Energy Project

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  1. Opportunities and Challenges: Update on the WSACC Heat to Energy Project Thomas Hahn, PE (CH2M HILL) Coleman Keeter (WSACC) Angela Roberts, PE (CH2M HILL)

  2. Agenda • Background/ Existing Facilities • Need for Project • Description of Project Features • Imported Biosolids Handling Facility • Heat Recovery and Power Generation System • Challenges and Opportunities • Path Forward • Questions

  3. Background / RRRWWTP Facilities • Serving Cabarrus County • 26.5 mgd capacity • High-Purity Oxygen Activated Sludge • Solids Handling System • Primary and Secondary Clarifiers • Gravity Thickeners • Dewatering Centrifuges • Multiple Hearth Furnace (MHF)

  4. Need for Project • Historically: • MHF operating well below permitted capacity • Autogenous burn 4 – 5 days / week • Maintaining temperature in MHF with fuel oil for remaining days • With imported solids • Reduced need for fuel oil • Optimized MHF operation • Revenue from imported solids • Solids handling alternative for other utilities • Heat Recovery / Power Generation • Green energy and revenue for WSACC

  5. Imported Biosolids Handling Facility – Design Capacities • Design Maximum Imported Biosolids Delivery/Conveyance Rate = 5.25 wet tons / hour • Storage Capacity of Imported Biosolids Handling Facilities = At least 1 day at design maximum imported biosolids delivery/conveyance rate

  6. Imported Biosolids Handling Facility – Process Flow Diagram

  7. Imported Biosolids Handling Facility - Truck Unloading • Two unloading “lanes” – one per solids receiving bin • Solids analysis • Weighing / recordkeeping

  8. Imported Biosolids Handling Facility - Solids Receiving Bins • 96 CY each (192 CY total). • Electrically actuated retractable covers • Leveling screws • Live Bottom Screws with Variable Frequency Drives • Load cells • Extraction screws and sludge mixer

  9. Imported Biosolids Handling Facility - Dewatered Sludge Pump • 45 gallons per minute (gpm) at 30% total solids • Screw feeder integral to dewatered sludge pump • Lubrication system (water injection) included to ensure reliable conveyance of imported cake • Piping and valving set up for multiple conveyance options.

  10. Heat Recovery and Power Generation System – Process Flow Diagram

  11. Heat Recovery and Power Generation System - Heat Recovery Unit • Replacement of the existing heat recovery unit at the Incinerator Building • Heat recovery unit completely contained within the existing building

  12. Heat Recovery and Power Generation System – HRSG Components Steam Drum Down-Flow Section Cross-Flow Section

  13. Heat Recovery and Power Generation System – HRSG Components (Up-Flow Section)

  14. Heat Recovery and Power Generation System - Steam Turbine Generator • Installed in new metal building • Process piping provided between the existing Incinerator Building and new Steam Turbine Generator Building • Overhead power lines to provide the power generated at the site back to the electrical grid.

  15. Challenges • Coordination, scheduling, and procurement for Owner-furnished equipment • Solids storage / conveyance equipment for Imported Biosolids Handling Facility • HRSG and STG for Heat Recovery and Power Generation System • Timing for bid of Heat Recovery and Power Generation System installation work • Contractor involvement with Owner-furnished equipment manufacturers • Imported dewatered sludge with wide variety of characteristics • Handling and controls • Incinerator shutdown for installation of Heat Recovery and Power Generation System equipment

  16. Opportunities • Cost-competitive all-weather biosolids disposal alternative • Optimization of biosolids feed quantity / quality to existing incinerator • Generation of green energy • Generation of revenue at WSACC

  17. Path Forward • Continuing successful Imported Biosolids Handling Facility operations • Operating January 2013 – present • Heat Recovery and Power Generation System • Construction work at site started in August 2013 • Concrete placement and backfill for STG Building now • Continuing mechanical equipment procurement • Incinerator shutdown, equipment installation, and startup • Anticipated completion of construction in May 2014

  18. Considerations for Interested Surrounding Utilities • Imported sludge with higher Total Volatile Solids (TVS) preferred for optimum operation of the MHF • Surrounding utilities may choose not to digest solids • Significant savings in O&M costs for those facilities

  19. Opportunities and Challenges: Update on the WSACC Heat to Energy Project Thomas Hahn, PEthomas.hahn@ch2m.com NC AWWA-WEA 93rd Annual Conference November 12, 2013

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